PM Review Winter 2015 by Inovar Communications

WINTER 2015

VOL. 4 NO. 4

POWDER METALLURGY REVIEW

ADVANCES IN PM ALUMINIUM TECHNOLOGIES FOR ENHANCING PM PROCESSING OF PM TITANIUM Published by Inovar Communications Ltd

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Managing Director Nick Williams Tel: +44 (0)1743 454991 Email: nick@inovar-communications.com Consulting Editor Dr David Whittaker Consultant, Wolverhampton, UK Production Hugo Ribeiro, Production Manager Tel: +44 (0)1743 454990 Email: hugo@inovar-communications.com Accuracy of contents Whilst every effort has been made to ensure the accuracy of the information in this publication, the publisher accepts no responsibility for errors or omissions or for any consequences arising there from. Inovar Communications Ltd cannot be held responsible for views or claims expressed by contributors or advertisers, which are not necessarily those of the publisher. Reproduction, storage and usage Single photocopies of articles may be made for personal use in accordance with national copyright laws. Permission of the publisher and payment of fees may be required for all other photocopying. All rights reserved. Except as outlined above, no part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, photocopying or otherwise, without prior permission of the publisher and copyright owner.

Submitting news and articles We welcome contributions from both industry and academia and are always interested to hear about company news, innovative applications for PM, technology developments, research and more. Please contact Paul Whittaker, Editor Tel: +44 (0)1743 454992 Email: paul@inovar-communications.com

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Lightweight materials for high volume applications For design engineers searching for lightweight, energy saving components, the choice of material is critical. Aluminium, processed via the Powder Metallurgy route, combines low weight with excellent formability at an affordable cost. The PM process allows high volume production of complex aluminium components for a wide range of applications. News of further investment in this sector by GKN Sinter Metals highlights the potential growth expected in the use of aluminium. In this issue of Powder Metallurgy Review we outline the PM aluminium production process and provide a number of industrial case studies that demonstrate the significant advantages that using this material has to offer (page 35). Another lightweight material, with characteristics that could lead to ever more diverse applications, is titanium. Currently the high cost and difficulty in processing this material limits its adoption, however much research in this area continues and we report on a number of processing routes discussed at the PM Titanium 2015 conference recently held in Lüneburg, Germany (page 57). The PM industry recently met in Reims, France, for the annual Euro PM2015 Congress. Organised by the EPMA the event attracted some 750 participants and included a well supported exhibition. We report on a technical session that focussed on technologies for enhancing the PM process (page 45). Paul Whittaker Editor, Powder Metallurgy Review

Tel: +44 (0) 207 1939 749 Fax: +44 (0) 1743 469 909 Email: jon@inovar-communications.com Design and production Inovar Communications Ltd. ISSN 2050-9693 (Print edition) ISSN 2050-9707 (Online edition)

Cover image

PM aluminium camshaft bearing caps (Courtesy GKN Sinter Metals)

Winter 2015

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Worldwide Global manufacturer of nodular and spherical aluminum powders, pre-alloyed aluminum powders, and aluminum premixes for PM www.ampal-inc.com www.poudres-hermillon.com

In the Americas Supplier of carbonyl iron and atomized stainless steel powders for the PM and MIM industries United States Metal Powders, Incorporated 408 U.S. Highway 202, Flemington, New Jersey 08822 USA Tel: +1 (908) 782 5454 Fax: +1 (908) 782 3489 email: rhonda.kasler@usbronzepowders.com

POWDER METALLURGY REVIEW

Winter 2015

in this issue

PM Titanium 2015: Developments in the powder metallurgical processing of titanium

Powder Metallurgy aluminium components offer lightweight solutions and high volume production

Powder Metallurgy aluminium components provide design engineers with a lightweight, energy saving option for a range of applications. The process can offer unique material properties along with the ability to produce high volumes of complex aluminium components. Dr.-Ing. Thomas Schubert and Dr.-Ing. Thomas Weissgärber, of Germany’s Fraunhofer IFAM in Dresden, describe the production process and provide a number of case studies to highlight the possibilities of aluminium PM.

PM Titanium 2015, the third in the international series of conferences specifically focussed on the processing, consolidation and metallurgy of titanium, was held in Lüneburg, Germany, from August 31 to September 3, 2015. Dr David Whittaker reports on selected material and processing developments presented at the event.

Japan’s auto industry drives advances in Powder Metallurgy technology

The winners of the JPMA’s 2015 Powder Metallurgy Awards showcase the continuing developments being made to further expand the range of applications for Powder Metallurgy. The winning components recognise innovations in new materials, manufacturing processes and component design in a number of important industries.

Euro PM2015: Technologies for enhancing the Powder Metallurgy process

A series of papers presented at the Euro PM2015 Congress, held in Reims, France, October 4-7, 2015, looked at the development of a number of design tools for improved control of conventional press and sinter Powder Metallurgy processes. These papers were included in a technical session specifically dedicated to presenting ‘Tools for Improving PM’. Dr David Whittaker reports on the key developments in this area.

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Industry news

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Industry News

industry news To submit news for inclusion in Powder Metallurgy Review contact Paul Whittaker, paul@inovar-communications.com

GKN Sinter Metals to invest $19.8 million in PM aluminium plant

Federal-Mogul Powertrain opens new manufacturing facility in China

It has been reported that GKN Sinter Metals plans to invest $19.8 million at its Conover facility in North Carolina, USA. The company plans to create 55 new manufacturing jobs in the next five years with the expansion of its state-of-the art Powder Metallurgy aluminium manufacturing plant. “The expanded Conover facility will build on GKN’s aluminium and lightweight technology capabilities that deliver lightweight and more energy-efficient designs and products to our customers right from our plant in North Carolina,” stated Alan Taylor, Vice President of Aluminium Technologies for GKN Sinter Metals. The GKN Sinter Metals plant makes camshaft caps and transmission ends that are used in General Motors Corp., Ford Motor Co. and Fiat Chrysler automobiles. “Unique GKN developed Powder Metal Aluminium materials open up fascinating application opportunities for multiple industries, not just automotive; this investment ensures GKN and North Carolina lead in aluminium Powder Metallurgy technology,” added Taylor. www.gknsintermetals.com

Federal-Mogul Powertrain has announced the opening of Federal-Mogul (Anqing) Powder Metallurgy Co., Ltd, a new joint venture manufacturing facility that will produce valve seats and guides for China’s domestic engine manufacturers. Federal-Mogul Powertrain will hold the majority share in the new joint venture. “Federal-Mogul Powertrain develops and delivers innovative technologies that meet specific regulatory and market requirements, helping our customers to improve fuel economy, reduce emissions and enhance vehicle performance,” stated Olaf Weidlich, General Manager, Valve Seats and Guides, Federal-Mogul Powertrain. “China is one of our key markets and our expanded valve seat and guide footprint here will further strengthen our capability to serve global customers, as well as regional Asian customers.” “The Anqing joint venture facility will manufacture a range of global-leading Federal-Mogul Powertrain patented powder metal technologies,” added Steven Krause, Director of Operations, East Asia. www.federalmogul.com

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Industry News

Johnson Electric completes acquisition of Stackpole International Johnson Electric Holdings Limited, headquartered in Hong Kong, has announced it has completed the acquisition of Stackpole International, headquartered in Ontario, Canada. Stackpole is a supplier of highly-engineered components to the automotive industry including engine and transmission pumps and Powder Metallurgy components. The company has nine manufacturing facilities located in North America, Europe and Asia. Dr Patrick Wang, Johnson Electric’s Chairman and Chief Executive, stated, “The combination of Stackpole’s pumps and powder metal expertise with Johnson Electric’s electric motor capabilities and global resources provides us with a unique opportunity to design and deliver integrated motorised pump solutions for our customers. These innovative new products will strengthen the Group’s position as a leading supplier to key engine and transmission applications that contribute to improved fuel economy and reduced emissions.” Johnson Electric acquired Stackpole from SI Investors, L.P., a limited partnership majority owned by Crestview Partners, in an all-cash transaction that valued Stackpole at C$800 million on an enterprise value basis. “We are very excited to take this next step with Johnson Electric,” added Peter Ballantyne, President and CEO of Stackpole. “It allows for the continued advancement of our core product portfolio and the development of innovative new technologies to meet the changing needs of our industry. It also offers our employees additional benefits from becoming part of a larger manufacturing group that brings global breadth and financial strength to support our growth initiatives over the long term.” www.johnsonelectric.com

Metaldyne expanding Bluffton facility Metaldyne, LLC, headquartered in Plymouth, Michigan, USA, has announced that it is expanding its Bluffton, Indiana, USA, plant to support several transmission related programmes through the supply of ready-to-assemble differential assemblies and aluminium valve bodies. Construction is expected to be completed by March, 2016. The expansion is the first step in a five year multi-million dollar capital investment plan to support the launch and production of new programmes. “Our Bluffton operation has grown significantly over the

past five years, and this expansion is indicative of our continued commitment to the community,” stated Thomas Amato, President and CEO, Metaldyne LLC, and Co-President, Metaldyne Performance Group (MPG). Each of the future programmes planned for the Bluffton facility involves internal components which will be supplied from other manufacturing locations of Metaldyne and also MPG companies, further expanding Metaldyne’s platform of vertical integration, the company stated. www.metaldyne.com

Royal Metal Powders increases capacity Royal Metal Powders, Inc., located in Maryville, Tennessee, USA, has announced Phase 1 completion of a $2 million expansion project. The company, a subsidiary of American Chemet, completed a 16,000 ft2 building expansion which will house new tin powder atomisation production and additional inventory control. Phase 2 of the expansion will include installing a larger second

induction furnace and auxiliary equipment in the water atomising department to increase capacity. Royal Metal Powders also announced it has been awarded an ISO 14001 Environmental Management System (EMS) certificate for the environmental management system as it pertains to the manufacture and sale of non-ferrous metal powders. www.chemet.com

Merger of NTN Powder Metal Corporation and Nippon Kagaku Yakin Japan’s NTN Corporation has announced that its consolidated subsidiaries NTN Powder Metal Corporation and Nippon Kagaku Yakin Co., Ltd. will be merged on December 1, 2015, to form NTN Advanced Materials Corporation. NTN Powder Metal Corporation was established in 1966 as Toyo Bearing Powder Metal Co., Ltd. The company is located in Kanie Town, Ama District, Aichi Prefecture, and in 1989 Changed its name to NTN Powder Metal Corporation. In recent years, the company successfully

developed high-strength sintered products with major improvements made to fatigue strength and density. Nippon Kagaku Yakin Co., Ltd. was originally established in Osaka in 1947. The company relocated its head office to Kameyama City, Mie Prefecture in 2012 having joined the NTN Group in 2011. The company is active in the manufacture and sales of sintered alloy products and magnetic material products required for medical devices and industrial machineries. www.ntn.co.jp

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Powder Metallurgy Review

Industry News

Japanese PM companies maintain growth despite decline in automobile production Most of the major Japanese Powder Metallurgy producers have reported steady growth in sales in the first half of the 2015/2016 financial year (April to September 2015), despite the continuing fall in automobile production in the country. According to statistics from the Japan Automobile Manufacturers Association (JAMA), output of all vehicles declined by 7.5% in the first 9 months of 2015 to 6.925 million units, of which 5,830 million were passenger cars, down 7.1%. More than 90% of Japan’s PM production goes to the automotive sector. Hitachi Chemicals Co Ltd Hitachi Chemicals Co Ltd, which includes the two main business segments of Functional Materials and Advanced Components and Systems, reported group sales up by 9.3% to Yen 275.6 billion ($2.235 billion) for the half year ended September 20, 2015 with net income up by 23.6% to Yen 17.1 billion ($137.8 million). The Advanced Components and Systems division, which includes structural PM parts and PM bearings as well as vehicle batteries, printed circuit boards and diagnostic instruments, reported a 21.2% increase in sales to Yen 137.3 billion ($1.113 billion). Segment profit was static at Yen 3.4 billion. www.hitachi-chem.co.jp Mitsubishi Materials Corp Mitsubishi Materials Corp (MMC) saw consolidated net sales for the six month period to September 30, 2015, total Yen 709.5 billion ($5.75 billion) – down 5.5% on the corresponding period in 2014. Operating profit increased by 6.3% to Yen 36.2 billion ($293.4 million). The decline in sales was attributed to the effect of lower copper and copper alloy prices. However, net sales of the Advanced Materials and Tools division (AM&T), which includes

Powder Metallurgy Review

cemented carbide (hardmetal) tools, structural PM parts and bearings, high performance alloy products and superalloys, were reported to have increased by 14.2% year-on-year to Yen 77.7 billion ($629.8 million). Operating profits for this division rose by 8% to Yen 9 billion. This division has particularly benefited from robust sales of cemented carbide products, including the recent acquisition of a 51% share-holding in Hitachi Metals Ltd’s cemented carbide business which took effect on April 1, 2015. MMC reported that the company had established cemented carbide end mill production in North America in April this year and that, in addition to adding capacity for carbide insert production in Spain in December 2014, it is also planning to start production of carbide drills and end mills in that country from March 2016. MMC will also double end mill capacity and launch carbide drill production in Indonesia in October 2016. The company claims to have more than 10% share of the global cemented carbide market. www.mmc.co.jp Sumitomo Electric Industries Ltd Sumitomo Electric Industries Ltd (SEI) based in Itami, Osaka, Japan, reported group sales for the period April to September 2015 of Yen 1,439 billion ($11.669 billion), an increase of 9.8% compared with the same period in the previous year. Group operating income was up by 10.4% to Yen 52.890 billion ($429 million). The largest SEI division, Automotive, which specialises in wiring harnesses, reported half year sales of Yen 765.5 billion ($6.2 billion), an increase of 7.5%. SEI’s Industrial Materials and Others division is the third largest after the Automotive and Environment and Energy divisions and includes the production of cemented carbides

Winter 2015

(hardmetals), PM parts, and PM magnets, as well as W, Mo, heavy metal, thermal management materials, ceramics, diamond tools and hardmetals produced at the fully owned A.L.M.T. subsidiary. The Industrial Materials and Others division saw half year sales barely increase compared with same period in 2014 to Yen 157.2 billion ($1.275 billion). Hardmetals (cemented carbides) sales increased slightly to Yen 45.7 ($370.6 million) for the six month period, and sales of Powder Metallurgy products saw no change at Yen 28.9 billion ($234.3 million). Sales at A.L.M.T. declined by nearly 10% to Yen 22.4 billion ($181.6 million). SEI is forecasting second half sales (October 1 to March 31, 2016) of Yen 187.7 billion ($1.522 billion) for the Industrial Materials division due in the main to increased sales of unspecified ‘Other’ products in this division. www.global-sei.com Fine Sinter Co Ltd Fine Sinter Co Ltd, based in Kasugai, operates two business segments which include Powder Metallurgy products based on structural PM parts and Metal Injection Moulding (MIM); friction materials (for railway applications) and hydraulic equipment such as motor pumps, solenoid valves, etc. Automotive PM products make up nearly 90% of sales and railroad applications, hydraulic equipment and industrial machinery the remainder. Fine Sinter Ltd reported a 3.8% increase in half year sales for the period ending September 30, 2015, to Yen 19.3 billion ($156.4 million), and a 185% jump in net income to Yen 1.009 billion. The company operates six production plants in Japan, China and Indonesia and is involved in a joint venture with another Japanese PM producer, Tokyo Sintered Metals Ltd, for producing PM parts in the USA at American Fine Sinter in Tiffin, Ohio www.fine-sinter.com

Industry News

Mehlmann appointed CEO of PMG Holding PMG Holding GmbH, Füssen, has announced that Ulrich Mehlmann has been appointed as the company’s CEO following the resignation of Dr Michael Krehl. The company stated that Dr Krehl asked the supervisory board to accept his resignation from his position as Chairman of the management board and CEO due to different opinions on group strategy. The Vermögensverwaltung Erben Dr Karl Goldschmidt, PMG’s parent corporation, added that it is still very interested in Dr Krehl’s expertise and knowledge and has asked him to sign on as an advisor. Dr Krehl’s career at the PMG group spans almost 20 years. The company added that he has advanced the global footprint of PMG, initiated the development of new products and focused PMG to become a customer oriented company with a high reputation in the automotive industry. Ulrich Mehlmann, 57, will succeed

Powder Metallurgy Review

Dr Krehl as CEO of PMG Holding with immediate Ulrich Mehlmann effect. Mehlhas succeeded Dr mann has a Michael Krehl as long trackCEO of PMG record in the automotive supply industry and has worked successfully for Delphi Inc., TRW Automotive Inc., Tenneco Inc. and most recently for Neumayer Tekfor GmbH (now part of the Amtek Group), both internationally and in Germany. PMG also announced that Michael Kroeker has been appointed CFO, replacing Juan Miguel Garcia. Kroeker has held various positions at automotive suppliers and most recently worked as CFO and deputy CEO at HIB Part Solutions, a leading supplier of interior components for the automotive industry. www.pmgsinter.com

Winter 2015

Kovohuty Metal Powders appoints new Sales Director Kovohuty Dolný Kubín s. r. o, located in Dolny Kubin, Slovakia, has appointed Thorsten Kiehnbast as the company’s new Sales Director for non-ferrous powders. Kovohuty is one of the largest metal powder producers in Europe with a total capacity of over 10,000 mt/ year. Kiehnbast began his career in Powder Metallurgy over 29 years ago at one of the largest metal powder producers in Germany. Kovohuty provides a range of atomised copper and copper alloys, tin powder, special ferro alloys as well as ferro silicon powders in different shapes and particle distribution. The product range also includes electrolytic copper powders of dendritic shape from low to high densities. www.kovohuty.com

Industry News

Avure Technologies changes its name to Quintus Technologies Avure Technologies AB, headquartered in Västerås, Sweden, has changed its name to Quintus Technologies AB. The US subsidiary, based in Columbus, Ohio is already named Quintus Technologies, LLC. Avure Technologies Inc. in the US will continue to focus on High Pressure Processing (HPP) food processing machines and Quintus Technologies in Sweden and the US will continue to focus on high pressure metal working and material densification equipment for the manufacturing industry. “Quintus Technologies is the undisputed leader within high pressure technology. Stemming from the Swedish electro technical company ABB, we have over sixty years of experience of developing, building and installing systems for customers within the automotive and aerospace sectors and general industry,” stated Jan Söderström, CEO of Quintus Technologies. The Quintus press was the world’s first high pressure press, a design that was used to manufacture synthetic diamonds and other products. “The name Quintus Technologies underlines that we continue to focus on industrial customers requiring systems for sheet metal forming or systems for cold or hot isostatic pressing. The re-naming is a small part of a substantial effort now launched to strengthen our offer and our position on all markets, from Europe to the Americas and especially Asia. The strong history of the Quintus name will help us to release the full potential,” added Söderström. www.quintustechnologies.com

Changes to HC Starck Board HC Starck has announced a number of changes to its Executive Board. As of October 1, 2015, the group with nearly 2,800 employees and fifteen production sites worldwide will be led by four Executive Board Members. Edmar Allitsch, previously Head of the Tungsten Powders division, will take over the sales organisation. Dr Michael Reiss, Chief Technology Officer of the group, will assume the lead of the Tungsten Powders

division. Reiss will also take over responsibility for the Surface Technology & Ceramic Powders. The Advanced Ceramic Components division will be handed over to Dr Matthias Schmitz, CFO of the group. Dr Andreas Meier continues to be responsible for the Tantalum/ Niobium Powders division and Dr Dmitry Shashkov remains head of the Fabricated Products division. www.hcstarck.com

PM Tooling System The EROWA PM tooling system is the standard interface of the press tools between the toolshop and the powder press machine. Its unrivalled resetting time also enables you to produce small series proﬁtably. www.erowa.com

Winter 2015

Powder Metallurgy Review

Industry News

Eisenmann and Ruhstrat merge to form new industrial furnaces company Eisenmann SE has announced that its business unit for process and high temperature technology will merge with Ruhstrat GmbH & Co. KG to create Eisenmann Thermal Solutions GmbH & Co. KG. The new organisation will be headquartered in Bovenden, Germany, although the Böblingen site will continue to operate. Eisenmann began a sales partnership with Ruhstrat GmbH several years before acquiring the company in 2011. “This move will allow us to collaborate more closely than ever, particularly in our industrial furnaces business,” stated André Görnhardt, Managing Director of Eisenmann Thermal Solutions. “By pooling the expertise that our teams have gained in thermal process technology over the last few decades, we will be better placed to effectively meet growing demand for global solutions, and to address the challenge of more complex processes,” added Görnhardt. The Ruhstrat and Eisenmann teams will undertake joint R&D projects in the areas of lightweight materials and carbon fibre, highperformance metals, technical ceramics, powder chemicals, catalysts and new materials. Moreover, the teams will consolidate and expand their marketing and engineering activities. A range of electrical technologies under the brand name of Ruhstrat will complement and enhance the existing Eisenmann product portfolio. Eisenmann stated that the new organisation will be well equipped to react to changing market conditions with greater speed and flexibility, whilst tailoring products and processes to continuously evolving customer needs. www.eisenmann.com www.ruhstrat.com

Powder Metallurgy Review

AP&C installs two new atomisation reactors Arcam AB has announced that its metal powder subsidiary AP&C, based in Montreal, Canada, is building its fourth and fifth reactors, adding significant capacity to its titanium and nickel superalloy powder manufacturing operation. AP&C uses proprietary plasma atomisation technology to produce highly spherical powders of reactive and high melting point materials such as titanium, nickel, zirconium, molybdenum, niobium, tantalum, tungsten and their alloys. Its powders are suited to a range of processes such as Additive Manufacturing, Metal Injection Moulding, Hot Isostatic Pressing and coating applications. “With this new generation of atomising technology, AP&C is now

SEM of Ti-6AL-4V powder from AP&C in a position to supply aerospace and medical part manufacturers’ titanium powders in volumes needed today and in the future. With a multiple reactor operation, AP&C can produce its standard products on dedicated reactors and equipment, therefore eliminating cross-contamination risks,” stated Jacques Mallette, President of AP&C. www.advancedpowders.com

EPMA launches Powder Metallurgy component awards The European Powder Metallurgy Association (EPMA) has announced the launch of its prestigious EPMA Powder Metallurgy Component Awards 2016. The competition is open to EPMA members who can demonstrate major achievements in the successful commercialisation or innovation of a product, taking into account cost savings, improved quality and stimulation of further usage of PM technology. The awards will be presented during the World PM2016 Congress & Exhibition to be held in Hamburg, Germany 9-13 October 2016. A short video on each winner will be prepared by the EPMA and all entries will be displayed as part of an Awards Showcase in the World PM2016 Exhibition. “The EPMA Powder Metallurgy Component Awards 2016 competition will provide an excellent opportunity for companies both to demonstrate their achievements

Winter 2015

and to promote the benefits of using the powder metallurgy process,” stated Joan Hallward, Awards Coordinator. “Over the years, the EPMA Awards have done much to promote and stimulate the interest in PM technology and we hope that all members will seriously consider submitting an entry in this World Congress year.” There will be four categories for the 2016 awards: • Additive Manufacturing • Hot Isostatic Pressing • Metal Injection Moulding • PM Structural (including Hard Materials and Diamond Tool parts) All entries must submitted via the EPMA Powder Metallurgy Component Awards 2016 website no later than May 6, 2016. www.epma.com/awards

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Industry News

MPIF’s founding Executive Director Kempton H Roll dies aged 92 Kempton H Roll, founding Executive Director of the Metal Powder Industries Federation (MPIF), trade association for the international metal powder producing and consuming industries, died on November 4, 2015, following a short illness. He was 92 years old. Well known in the national and international metalworking communities, Roll retired in 1988 after a 40 year career. He joined the Lead Industries Association in 1948 as Technical Director with responsibilities for the former Metal Powder Association (MPA), forerunner of MPIF. He was named Executive Director of the MPA in 1956 and helped found the MPIF in 1957 as the umbrella organisation representing

different sectors of the metal powder producing and consuming industries. Roll was also executive director of APMI International, the professional society for Powder Metallurgy that he helped found in 1959, and served as publisher of the International Journal of Powder Metallurgy. He attended Carnegie Institute of Technology and graduated from Yale University in 1945 with a degree in metallurgical engineering and served in the Pacific during World War II as a bomb disposal officer with the US Navy. He earned a master’s degree from Brooklyn Polytechnic Institute in 1953. In 1992 Roll received the MPIF’s prestigious Powder Metallurgy Pioneer Award and in 1988 the

Kempton H Roll, founding Executive Director of the MPIF Distinguished Service to Powder Metallurgy Award. In 2007, to honour his lifetime accomplishments, MPIF created the Kempton H Roll PM Lifetime Achievement Award which is presented every four years. He was named a Fellow of ASM International in 1987 and was a Legion of Honour member of the Minerals, Metals and Materials Society. www.mpif.org

Bodycote increases Carpenter Technology reports first HIP capacity quarter results Bodycote has announced further expansion of its high pressure Hot Isostatic Pressing (HIP) capability with the addition of a new midrange vessel to increase its volume capacity. The new system will serve customers globally from its eastern USA location, adding to the company’s extensive range of installed capacity across North America and Europe. The new HIP system will be focused on high pressure developments in aerospace and advanced materials. The unit is capable of processing up to 2,000 bar (30,000 psi) and temperatures up to 2,000°C. Bodycote operates over 50 HIP vessels in multiple locations. Processing capability can accommodate components up to 2 m diameter by 3.5 m high, weighing 0.1 kg to over 30,000 kg. In addition to standard quality and environmental certifications, Bodycote’s HIP facilities hold ASTM, NORSOK and Nadcap accreditations. www.bodycote.com

Carpenter Technology Corporation has announced financial results for the quarter ended September 30 2015, reporting net income of $8.9 million. This compares to a reported net income of $13.5 million in the same quarter last year. Net sales for Q1 of fiscal year 2016 were $455.6 million, and net sales excluding surcharge were $385.1 million, a decrease of $55.0 million (or 12%) from Q1 last year, on 19% lower volume. Operating income was $24.8 million, an increase of $2.7 million on the previous year’s first quarter. Operating income, excluding pension earnings, interest and deferrals and restructuring charges and special items, was $32.6 million, an increase of $8.1 million (+33%) from the first quarter of the prior year. “Overall I am encouraged by how the team has responded to the industry challenges in the quarter,” stated Tony Thene, Carpenter’s President and Chief Executive Officer. “We continued to drive operating

cost improvements and reduce overhead costs in our Specialty Alloys Operations (SAO) segment as operating margins were relatively flat sequentially notwithstanding the significantly lower volume. The cost improvement initiatives are particularly important in this environment of declining volumes and will better position us to capitalise on the operating margin benefits from these cost structure changes as the volumes return.” “As expected, our Performance Engineered Products (PEP) segment was impacted by the lower sequential demand in the current quarter for Aerospace titanium fastener materials and powder products for the Industrial and Consumer end-use market. The operating income results of the Oil and Gas businesses in PEP were sequentially flat as we continue to manage cost structure and take appropriate actions as a result of the depressed activity in this end-use market,” added Thene. www.cartech.com

Winter 2015

Powder Metallurgy Review

Industry News

AIMS appoints new Director of Business Development and Insight Advanced Interactive Materials Sciences Ltd (AIMS), based in Peterborough, UK, has announced that Dr Raja Khan has joined the company as its new Director of Business Development and Insight. Dr Khan, a leading expert in the world of advanced metals and Hot Isostatic Pressing (HIP) techniques, joined the company from The Welding Institute (TWI), Cambridge, where he was Senior Project Manager. Dr ® as Khan will continue his position visiting scholar at the University of Birmingham. His key focus at AIMS will be to drive sales of the company’s Hot Isostatic Pressing consolidated components featuring its Sagittite® range using powdered metal chemistry, together with near-net shaping methods. “Powder Metallurgy and near net shaping technologies are the future

in component manufacturing, which is why I’m so excited to be joining AIMS,” stated Dr Khan. “Through its patented Sagittite® range, AIMS is carving out a reputation for providing the highest quality, wear- and corrosion-resistant solutions for customers across the globe, ranging from Food processing to Oil & Gas and Aerospace industries.” “Together with AIMS’ near-net shape capability, which unlike traditional cast and forge processes enables components to be manufactured without the need for second stage machining, there is a great opportunity for continued sales growth.” AIMS Managing Director Mark Hodgkins added, “The appointment of someone of Dr Khan’s calibre and reputation in the Powder Metallurgy and near-net shaping world is a real coup for AIMS. With his technical

Dr Raja Khan has joined AIMS as its new Director of Business Development and Insight knowledge and contacts across a breadth of manufacturing sectors globally, Dr Khan will be pivotal to our future growth in terms of product development and sales.” AIMS was founded 17 years ago by the company’s Technical Director Geoffrey Archer. In 2012 the company received inward investment from Alycidon Capital Ltd and has seen continued growth in markets across Europe, China, Australia and the USA. www.aimsltd.com

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Powder Metallurgy Review

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Industry News

Industrial Solutions Functional Chemicals

Kennametal announces changes to management team and relocation plans Kennametal Inc. has announced two changes to its executive management team. As of October 1, 2015, Peter Dragich will become Kennametal Vice President and Executive Vice President of the Infrastructure business segment and as of September 30, 2015, Greg Temple will become Vice President and Chief Supply Chain Officer. Dragich will take global responsibility for growth of the company’s engineered products and surface technologies, serving customers in earthworks, energy and process industries. He joined Kennametal in October 2012 as Vice President Integrated Supply Chain and Logistics. Prior to Kennametal, Dragich was Vice President, Global Field Operations, Climate, Controls, and Security for United Technologies Corporation. He also served in several manufacturing management positions at Ford Motor Company and was a Sergeant in the United States Marine Corps. In addition, he brings more than 25 years of experience in supply chain management and cross-functional collaboration. Temple will lead the company’s global manufacturing operations, distribution centres and reconditioning facilities, as well as supply chain management, supplier sourcing, advanced manufacturing engineering and environment, health and safety. He joins Kennametal from Sensata Technologies where he served as Senior Vice President of Global Operations. He previously held global operations leadership positions with Ecolab Corporation, Avery Dennison Corporation and The Clorox Company and has served as an operating partner for the private equity firm Apollo Global Management. Relocation of headquarters Kennametal Inc. has also announced plans to relocate its world headquarters to an urban location as it repositions the company for growth in global markets, recruits new talent and strengthens innovative partnerships with leading universities. The company has expanded its presence in Pittsburgh, Pennsylvania, and will move its corporate leadership team to the US Steel Tower in downtown Pittsburgh, while maintaining a substantial presence at its current headquarters in Latrobe, Pennsylvania. “An urban location puts Kennametal in closer proximity to major universities, public transportation and the airport, while presenting us with new opportunities to innovate, grow and recruit new talent,” stated Kennametal Chairman of the Board, Bill Newlin. “The company believes that with cooperation of Pittsburgh city, county and state officials an agreement for a new building in Pittsburgh is realistic.” www.kennametal.com

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Winter 2015

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Industry News

MPIF elects new President The Metal Powder Industries Federation (MPIF) has announced that Patrick J McGeehan, Vice President and General Manager of the specialty metal products division, Ametek, Inc., was elected the 28th President of the federation, succeeding Richard Pfingstler of Atlas Pressed Metals, DuBois, Pennsylvania. McGeehan’s two-year term took effect at the conclusion of the federation’s annual meeting recently held in Austin, Texas. Two of the MPIF’s six associations also installed new Presidents during the annual meeting. Dean Howard, Vice President, Sales, North American Höganäs, Inc., was elected president of the Metal Powder Producers Association (MPPA). Thomas K Houck, Vice President, US MIM operation, ARCMIM, was elected president of the Metal Injection Molding Association (MIMA). McGeehan’s PM career spans over 30 years. He earned his BS and MS degrees in Materials Science & Engineering from Drexel University. McGeehan has been with Ametek, Inc., for seven years and, prior to Ametek, Inc., he was at Hoeganaes

Corporation for 25 years, most recently as Senior Vice President, Operations and Technology. McGeehan most recently served as president of the Metal Powder Producers Association (MPPA) and a member of the MPIF Board of Governors. Active in the PM industry for many years, McGeehan received the MPIF Distinguished Service to Powder Metallurgy Award in 2011. He is also a member of the MPIF Awards Committee, served on the MPIF Technical Board, co-chaired MPIF’s Roadmap Strategy Board and has been a member of APMI International for over 30 years. McGeehan co-chaired the 1990 annual MPIF PM conference in Pittsburgh, Pennsylvania, as well as the 2008 PM World Congress in Orlando, Florida. Howard has been promoting PM technology since entering the industry in 1991 as a Sales Manager for Abbott Furnace Company. In 1997, he joined Pyron Corporation and was retained after its acquisition by North American Höganäs, where he is currently Vice President of Sales. A

Alcoa to split business to form two independent companies Alcoa’s Board of Directors has unanimously approved a plan to separate into two independent publicly-traded companies. The move will see the formation of an ‘Upstream Company’ and a ‘Value-Add Company’ and is expected to be completed in the second half of 2016. The Upstream Company will comprise five business units that today make up Global Primary Products - Bauxite, Alumina, Aluminium, Casting and Energy. The Value-Add Company will include Global Rolled Products, Engineered Products and Solutions, and Transportation and Construction Solutions. Alcoa stated that both independent companies will attract an investor base best suited to their unique value

Powder Metallurgy Review

proposition and operational and financial characteristics. After the separation, the Upstream Company, with its strong history in the aluminium and alumina markets, will operate under the Alcoa name. The Value-Add Company will be named prior to closing. “In the last few years, we have successfully transformed Alcoa to create two strong value engines that are now ready to pursue their own distinctive strategic directions,” stated Klaus Kleinfeld, Chairman and Chief Executive Officer. “After steering the Company through the deep downturn of 2008, we immediately went to work reshaping the portfolio. We have repositioned the upstream business; we have an enviable bauxite position

Winter 2015

Patrick J McGeehan, MPIF President (left), Dean Howard, President of the Metal Powder Producers Association (centre) and Thomas K Houck, President of the Metal Injection Molding Association (right) member of the MPPA Board of Directors since 2009, Howard obtained his PMT Level I certification in 2004 prior to joining the APMI Board of Directors in 2007. He served as APMI president from 2010 to 2014. Houck’s interest in engineering and PM began in 1987 while serving in the US Army. He honed his management skills at Zenith Sintered Components, MascoTech/ Metaldyne Sintered Components and Cloyes Gear & Products before entering the MIM industry. An active member of MIMA, Houck co-chaired the MIM2015 conference and will co-chair the upcoming MIM2016 conference. www.mpif.org

and are unrivalled in Alumina, we have optimised Aluminium, flexed our energy assets and turned our casthouses into a commercial success story. The upstream business is now built to win throughout the cycle. Our multi-material value-add business is a leader in attractive growth markets. We have intensified innovation, made successful acquisitions, shed businesses without product differentiation, invested in smart organic growth, expanded our multi-materials profile and brought key technologies to market; all while significantly increasing profitability,” added Kleinfeld. Alcoa recently announced a $60 million expansion of its R&D centre to grow its Additive Manufacturing business as well as a further $22 million investment in HIP technology at its facility in Whitehall, Michigan. www.alcoa.com

Industry News

Miniature rotary batch mixer from Munson Machinery

MIM2016 Conference Programme

Munson Machinery, Utica, USA, has announced the introduction of a new miniature rotary batch mixer to its range. The model MX-1-SS is capable of blending up to 28 litres of dry bulk ingredients, with or without liquid additions, in ratios down to one part per million with total uniformity in two to three minutes, regardless of disparities in the bulk densities, particle sizes or flow characteristics of batch ingredients, the company states. The mixer is equally efficient down to five percent (1.4 litres) of rated capacity, making it suitable for accurately determining outcomes when scaled up to larger Rotary Batch Mixers. The company currently offers six miniature rotary batch mixer models in maximum batch capacities of 7 to 425 litres or 1 to 544 kg.

The MIM2016 International Conference on the Injection Molding of Metals, Ceramics & Carbides will take place at the Hotel Irvine in Irvine, California, USA, from March 7-9 2016. The conference, sponsored by the MPIF’s Metal Injection Molding Association (MIMA), has the objective of exploring the latest advances in the field of Powder Injection Moulding. In addition to the conference there will be an optional Powder Injection Moulding Tutorial taking place on March 7. Conducted by Prof Randall German, San Diego State University, the course is an ideal way for anyone looking for a solid grounding in PIM to obtain a comprehensive foundation in a short period of time. www.mpif.org

The Miniature rotary batch mixer from Munson blends batches up to 28 ℓ,or 45 kg, of dry bulk ingredients, with or without liquid additions Also offered are large-scale, in-line rotary batch mixers with capacities of 142 litres to 17 m3, continuous rotary blenders, ribbon/ paddle/plow blenders, vee-cone blenders, high intensity blenders and fluidised bed mixers. Size reduction equipment produced by the company includes screen classifying cutters, centrifugal impact mills, rotary lump breakers, attrition mills, hammer mills and shredders. www.munsonmachinery.com

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Powder Metallurgy Review

Winter 2015

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Industry News

New 2016 edition of PM Standard Test Methods

Plansee wins Schneider Electric supplier award

The MPIF has announced the publication of its 2016 edition of Standard Test Methods for Metal Powders and Powder Metallurgy Products. The MPIF Standard Test Methods publication contains 42 standards covering terminology and recommended methods of test for metal powders, Powder Metallurgy and injection moulded parts, metallic filters and PM equipment. The most current versions of these standards, which are used in the manufacture of both metal powder and Powder Metallurgy products, are required by Quality Assurance programmes in order to maintain full compliance. The 2016 edition contains revisions to 27 standards, including major rewrites of Standards 10 (PM Tensile Properties) and 32 (Estimating

The two production sites of Plansee BU Power T/D, located in Seon and Shanghai, have been named as preferred suppliers to Schneider Electric for the fifth time in a row. Plansee manufactures switch contact components from WCu and CuCr for Schneider Electric. “We are proud of our employees’ performance in a difficult market environment. They were successful to differentiate our offer in such a competitive market environment,” stated Frank Müller, Head of BU Power. Plansee uses Powder Metallurgy to produce the metallic composite materials in switch contacts. The process offers harmonized material properties and an exceptionally homogeneous material composition. www.plansee.com

Particle Size Using Air Permeability) and includes new Precision Statements for five standards. A new General Information VI section has been added to this edition that provides details (QR codes and Internet links) on viewing educational video clip demonstrations of the working mechanics of a number of cited test methods. Publication of the 2016 edition of this standard renders the 2012 edition (and prior editions) obsolete and the MPIF states that previous editions should be no longer distributed and should be destroyed. www.mpif.org

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Winter 2015

Powder Metallurgy Review

Industry News

GKN Sinter Metals receives Johnson Controls Performance Award

ASM Handbook on Powder Metallurgy

Powder Metallurgy parts maker GKN Sinter Metals’ facility in Bonn, Germany, has received a Silver Performance Award 2015 from Johnson Controls (JCI), one of the world’s largest automotive suppliers. The award was for supplying PM components used in the manufacture of car seats. Timothy Laughlin, RPPC Engineering Director and Thomas Jeworrek, Key Account Manager, accepted the award during the Global Automotive Seating Supplier Awards and Expectations Day on GKN Sinter Metals’ behalf. The award is presented to suppliers who excel in key business areas such as quality, logistics, technology and service. JCI is one of GKN Sinter Metals’ top ten customers in Bonn. The plant has shared a long-term customer relationship with Keiper, which became a subsidiary of JCI in 2011, having already received Keiper Supplier Award in 2006, 2008, 2009 and 2010. It also received a JCI

The 2015 edition of ASM Handbook, Volume 7: Powder Metallurgy, edited by Prasan K Samal and Joseph W Newkirk, is now available from the publishers. The latest 907 page edition focuses on conventional press and sinter Powder Metallurgy (PM) and includes a new section on Metal Injection Moulding (MIM). The revised volume is organised in two parts. The first part, following an introductory division on history and material standards, covers the basic principles and techniques that are common to all PM materials. The second part of the handbook covers detailed information on PM technology as it applies to individual metal/alloy families. Within each material-specific division, the information presented follows the typical production steps and processes as they are currently used in industry. www.asminternational.org

Keiper awards from 2006 to 2010 Silver Performance Award in 2011. Since 2000, GKN Sinter Metals Bonn has supplied Keiper with metal wedges that enable seats to recline. By 2014 GKN Sinter Metals had produced one billion wedges at Bonn, all made without any defects. Matthias Voss, Plant Manager of the Bonn plant, stated, “We are delighted to receive this award from our valued customer Johnson Controls. It validates all the hard work by our employees to produce quality products and our commitment to our customers to be partners in creating innovative solutions.” www.gknsintermetals.com

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Winter 2015

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Industry News

Howards Racing Components offers high performance powder forged connecting rods to aftermarket Howards Racing Components, based in Oshkosh, Wisconsin, USA, is offering a range of powder forged Powder Metallurgy connecting rods to the performance aftermarket sector. As reported by enginelabs. com, the connecting rods are produced in partnership with GKN Sinter Metals and together the companies have developed a product that is aimed at performance engine builds. “Forged powder metal technology features an extremely dense grain structure when compared to a billet or conventional forging,” stated HRC’s President, Steve Mugerauer.

“It uses task-oriented steel materials that are too costly for high performance OEM connecting rods. Howards tailored the composition to excel in a racing environment when developing these products.” Powder forging can offer significant advantages in the production of connecting rods. It offers higher material utilisation over drop forged alternatives, as well as better weight variation control. The process involves a reduced number of machining operations and has lower overall production costs. “We used CAD solids modelling for proof of concept and machined

YaHao Materials & Technology aims to be China’s leading alloy powder supplier

Molycorp to end rare earth production at Mountain Pass

Atomisation for metal powders short course returns

Molycorp, Inc. has announced that it will end production of rare earths at its Mountain Pass facility in Calilfornia, USA, by October 20, 2015. The move follows the company’s statement in June this year that it had filed for Chapter 11 bankruptcy protection to restructure $1.7 billion of debt. Molycorp stated that it will transition its Mountain Pass rare earth facility to a ‘care and maintenance’ mode while it plans to continue serving its rare earth oxide customers via its production facilities in Estonia and China. Rare earth pricing, which has declined dramatically over the past four years, was named as a key factor in the decision to suspend rare earth production at the site. Customers of the company’s rare earth magnetic materials, as well as its rare earth-based water treatment products, will not be impacted, the company stated. www.molycorp.com

Atomising Systems Ltd and Perdac Ltd (now part of CPFResearch Ltd) have announced that their popular two day intensive course, Atomisation for Metal Powders, is scheduled to take place in Manchester, UK, February 25-26, 2016. The course, now in its 12th year, will consist of presentations from Andrew Yule (Emeritus Professor Manchester University), John Dunkley (Chairman, Atomising Systems Ltd) and Dirk Aderhold (Technical Director, Atomising Systems Ltd). Sessions will cover the main methods of atomising metals, the specific requirements for different classes of metal, the design, operation and economics of plant, measurement methods and an introduction to modelling and prediction techniques. All current atomiser types are covered together with a wide range of metals and powder types. www.atomising.co.uk www.cpfresearch.com

YaHao Materials & Technology Co,. Ltd., based in Hebei Province, China, is one of the region’s largest manufacturers of soft magnetic powders. The company is now offering a wide range of other alloy powders for various applications and is aiming to be the leading alloy powder supplier in China. Sales in 2014 were reported to be around 10.1 million RMB with exports accounting for around 50% of the company’s total consolidated sales. The company has more than 120 employees and alloy powder production for the year totalled 2,365 tons. YaHao states that it has multiple water and gas atomisation systems with alloy powder capacity currently being around 5,000 tons per year. Its range includes powders for Metal Injection Moulding, pre-alloyed powder for diamond tools, amorphous powder and single element powders. www.yahaochina.com

Powder Metallurgy Review

Winter 2015

The hot forging process uses a 750 ton press to ensure the material’s dense structure is finalised prior to the machining operations (Image courtesy enginelabs.com) models from billet. We also use Finite Element Analysis to accurately simulate stress and reaction to stress, which allows for better strength and weight reduction in the correct places,” added Mugerauer. www.howardscams.com

Industry News

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Industry News

Researchers combine diamond and cubic boron nitride with a novel alloying process for a superhard material Researchers at Sichauan University, China, University of Nevada, USA, and the Chinese Academy of Sciences, China, have published work on the combination of diamond and cubic boron nitride to form a new superhard material suitable for cutting tool applications. Diamond and cubic boron nitride (cBN) as conventional superhard materials have found widespread industrial applications, but both have inherent limitations. Diamond is not suitable for high-speed cutting of ferrous materials due to its poor chemical inertness, while cBN is only about half as hard as diamond. Because of their affinity in structural lattices and covalent bonding character, state the authors of the paper, diamond and cBN could form alloys that can potentially fill the performance gap. However, the idea has never been demonstrated because samples obtained in the previous studies were too small to be tested for their practical

performance. The paper, Diamond-cBN alloy: A universal cutting material, published in Applied Physics Letters, reports the synthesis and characterisation of transparent bulk diamond-cBN alloy compacts whose diameters (3 mm) are sufficiently large for them to be processed into cutting tools. The testing results show that the diamond-cBN alloy has superior chemical inertness over polycrystalline diamond and higher hardness than single crystal cBN. High-speed cutting tests on hardened steel and granite suggest that diamond-cBN alloy is indeed a universal cutting material. The researchers tested the cutting performances of the alloy on hardened steel and granite bars on a CNC lathe. They found that the diamond-cBN alloy rivalled polycrystalline cubic boron nitride’s wear and tool life on the steel samples and exhibited significantly less wear when cutting through

Bulk diamond-cBN alloy samples synthesized at 20 GPa/2200 °C with a diameter of ~3 mm, over a copper screen to exhibit its transparency c and d: Polished rake faces of diamond-cBN alloy cutters (D. W. He/ SCU) granite. The alloy also demonstrated a more preferable high-speed cutting performance than either polycrystalline CBN or commercial polycrystalline diamonds. Future work for the team involves developing synthesis technology for centimetre sized diamond-cBN alloy bulks to bring the process up to industrial-scale production. http://apl.aip.org

Dr. Fritsch delivers 1000 field-assisted sintering presses Dr. Fritsch, a manufacturer of field-assisted sintering systems based in Fellbach, Germany, has announced the delivery of its 1000th sinter press. The company stated that Oxford University, UK, received the new sinter press machine which is capable of sintering a wide range of materials up to 2,400°C at a maximum pressure of 260 kN. It features a fine vacuum level of 0,05 mbar and is equipped with many sensorial options, some customised or developed especially for the university. The Field-Assisted Sintering Technique (FAST) systems from Dr. Fritsch utilise Joul`s Heating and achieve short sinter cycles. This, states the company, allows it to

Powder Metallurgy Review

achieve very high densities and a very homogeneous material structure. The DSP-507 FAST sinter press delivered to Oxford University will help researchers develop innovative Powder Metallurgy solutions for various applications. The university performs research for a number of industrial customers. “It was important for us to buy a machine from a manufacturer which is also able to deliver turnkey production equipment with this technology to our industrial customers,” stated Alasdair Morrison, Oxford University. “The applications for field-assisted sintering are steadily increasing. Examples are thermoelectric materials for generating energy out of waste heat and nano-material

Winter 2015

Jens Huber (left) and Alasdair Morrison (right) with the 1000th FAST sinter press (type DSP-507) applications. A profound R&D work is very important for developing such new applications and therefore we are very happy that our 1000th machine goes to a high-class R&D facility like Oxford University,” stated Jens Huber, International Sales Manager, Dr. Fritsch business unit Powder Shaping Technologies. www.fastsintering.com

Industry News

Porvair supplies sintered filters to major South African refinery Porvair Filtration Group, UK, has announced it has supplied highly efficient and durable sintered metal powder Triple Element Filters (TEFs) to South Africa’s national oil company, PetroSA, through its Johannesburg-based agents, Sagisa Process Engineering (Pty) Ltd. PetroSA, situated in Mossel Bay, is the world’s third largest gas-to-liquid (GTL) facility and produces some of the cleanest fuels on the market by using leading environmentally friendly processes. Porvair supplied 2.4 m long TEF assemblies, manufactured in the UK, as well as sintered metal mesh fuse assemblies manufactured at the company’s US factory. The TEFs and mesh fuses were fitted into tubesheets and installed into five vessels, supplied locally by Sagisa. The complete vessels were then shipped to the PetroSA refinery and are now helping to clean up catalyst

fines - very small particles used in the Fluid Catalytic Cracking process (FCC) of most large, modern oil refineries and in the hydrogen process stream at Mossel Bay. The assemblies were selected by PetroSA for their ability to operate reliably at temperatures in excess of 400°C and at a pressure of around 25 bar. The vessels are located above the Catalyst Reduction Reactor (CRR), enabling the TEF assemblies to be cleanable in situ, therefore operating in a cyclic back flush operation to remove the catalyst cake from the filter surface of the TEFs. The disengaged catalyst then falls into the CRR. As a consequence, the TEFs are able to operate for a prolonged period in an aggressive environment, only periodically requiring to be removed and chemically cleaned before then being re-installed. “Porvair is proud to be manufac-

Triple Element Filter from Porvair turing components for one of the world’s most environmentally friendly oil companies. We believe that our filtration expertise can help drive further efficiency and cost reductions at the Mossel Bay refinery, in turn providing sustainable growth,” stated Market Manager, Andrew Fairlie. “PetroSA already produces some of the cleanest fuels available and we are certain that the provision of our TEF and mesh fuse assemblies, with their high performance capabilities, will only enhance that reputation by ensuring security and continuity of supply.” www.porvairfiltration.com

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Winter 2015

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Industry News

Rosenhain Medal awarded to Banerjee Dr Sarbajit Banerjee, an affiliated faculty member in the Department of Materials Science and Engineering at Texas A&M University, USA, has been awarded the Rosenhain Medal and Prize by the Institute of Materials, Minerals, and Mining (IOM3), UK, for his research in new materials design. The award was instituted in 1951 to honour the memory of the German-born Australian metallurgist Walter Rosenhain. Banerjee, who is a professor in the Department of Chemistry at Texas A&M, received the honour in recognition of distinguished achievement in any branch of materials science by a researcher under the age of 40. It is the highest young researcher award presented by the organisation. The award recognises the accomplishments of Banerjee’s research group related to phase transformations in complex oxides, Powder Metallurgy of light metals and the ability to bring together theory, measurement and applications. Banerjee received his undergraduate education at St. Stephen’s College, Delhi, India, and his doctorate at Stony Brook University, New York, USA. Before starting at Texas A&M University he was an Assistant and Associate Professor at the University at Buffalo and The State University of New York. His research specialities include solid-state and materials chemistry, nanoscale materials, electronic structure, chemical imaging and X-ray spectroscopy, thin films and coatings, light metals and nanocomposites. www.engineering.tamu.edu

Powder Metallurgy Review

Kennametal recognised with Bosch Global Supplier Award Kennametal Inc. has announced that it has been awarded the Bosch Global Supplier Award 2015 from Robert Bosch GmbH. The biannual award recognises outstanding performance in the manufacture and supply of products or services, notably in the areas of quality, costs, logistics and innovations.“It is an honour to be recognised by Bosch as the only tooling manufacturer to receive their Global Supplier Award,” stated Don Nolan, Kennametal President and CEO. Kennametal was among 58 suppliers out of 35,000 that Bosch presented with the prestigious award. To be eligible, suppliers must deliver best-in-class services, quality

Prof Dr Karl Nowak, President Corporate Sector Purchasing and Logistics Robert Bosch GmbH, at the award ceremony of the ”Bosch Global Supplier Award 2015” in Stuttgart and total cost of ownership as well as guarantee global footprint and significant sales in the purchasing category. “The Bosch Global Supplier Award honours our top suppliers, who play such a key role in Bosch’s success,” added Dr Volkmar Denner, Chairman of the Bosch board of management. www.kennametal.com

Sintering Fundamentals II – new publication includes key papers on sintering A new 274 page publication entitled Sintering Fundamentals II, edited by Professor Dr G S Upadhyaya, is now available from Trans Tech Publications Inc. Following the publication of the first volume in 2009, the second volume contains seven papers written by respected authors from five countries. The first paper, authored by Professor Upadhyaya (India), covers historical aspects of sintering fundamentals which began in the middle of the 20th century. The coverage of literature is extensive, most of which is available only in the print form. The second paper, authored by R M German (USA), presents an approach that links to the global energy reduction during sintering. The third paper authored by M S Kovalchenko (Ukraine) is entitled ‘Rheology and Kinetics of Pressure Sintering’.

Winter 2015

The following paper by Austrian scientists, H Danninger and C Gierl-Mayer covers the sintering aspects of Cr- containing steels in which dilatometry coupled with mass spectroscopy is shown as a good tool for sintering process control. This is then followed by a joint paper from Russian scientist I Konyashin with Austrian scientist W Lenguer, which encompasses functionally graded cemented carbides. The next two papers deal with ceramic systems. ‘Doped Ceria based Oxide Fuel Cell Electrolytes and their Sintering Aspects’, presents an exhaustive review (P Datta, India). Finally, in the last paper K Biswas and others (India) discuss sintering and microstructural modifications of seeded and neodymium doped lanthanum hexaaluminate. www.ttp.net

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Industry News

Fachmetall presents awards to R. Biemmetech and X-Pore Fachmetall GmbH, Radevormwald, Germany, a metallurgical laboratory specialising in Powder Metallurgy and wrought materials, has announced the winners of its annual industry wards. The Fachmetall QM Context Award was presented to R. Biemmetech srl, based in Fano, Italy, received for outstanding efforts in enhancing its quality management procedures. R. Biemmetech is a technologically oriented company in the sintered metal industry specialising in precision gears and structural parts, stainless steel and bronze PM parts, including the design and manufacture of the tooling. Its products are used in the automotive industry and in many other technically demanding applications. The company’s PM plant established a sound technology base with

Powder Metallurgy Review

the support of Fachmetall and took appropriate action to improve the quality of its products. Ongoing efforts are being made to maintain and continuously improve the product quality. For the first time, this year’s Fachmetall PM Qualification Award was presented to a company with a main focus outside the metals sector. X-Pore bv in Helmond, The Netherlands, develops porous ceramic membranes for water treatment and other technical applications. A new project has been started at X-Pore that aims to combine porous metal filters with a ceramic membrane surface structure. www.rbiemmetech.it www.x-pore.com www.fachmetall.de

Winter 2015

Holger Davin of Fachmetall (left) and Dr Georg Schlieper (right) presenting the Fachmetall QM Context Award to Massimiliano Rovinelli and his engineers

Dr Rinse A Terpstra (middle) with his wife and daughter receiving the Fachmetall PM Qualification Award from Holger Davin (left) and Dr Georg Schlieper (right)

Industry News

Simplifying the recycling of permanent magnets The Fraunhofer Institute for Silicate Research ISC, based in Alzenau, Germany, has reported a new, simplified process route for the recycling of permanent magnets that is claimed to enable the fast and cost-effective recycling of the rare earth elements neodymium and dysprosium. Currently, methods of recycling permanent magnets involve extracting the rare earth elements from the magnet in a laborious and expensive process. The scientists of the Fraunhofer Project Group for Materials Recycling and Resource Strategies IWKS in Alzenau and Hanau and of the Fraunhofer Institute for Silicate Research ISC are now pursuing a different approach. “Instead of trying to regain each individual type of rare earth, we focus on recycling the entire material, meaning the complete magnet - and this in only a few steps,” stated Oliver Diehl, a scientist in the Project Group IWKS. “This process is much easier and more efficient, because the composition of the material is already almost as it should be.”

The new recycling method utilises the melt spinning process, also known as rapid solidification, where researchers begin by melting the magnet. The liquefied material, heated to more than 1000°C, is directed via a nozzle onto a watercooled copper wheel that rotates at a speed of 10 to 35 metres per second. As soon as the melted droplet comes into contact with the copper, it transfers its heat to the metal within fractions of a second and solidifies into flakes. If the melted material was allowed to solidify in the normal way the atoms would line up in rows, in a crystal lattice. In the melt spinning procedure, however, crystallisation is avoided with either an amorphous structure being formed, in which the atoms are completely irregularly arranged, or a nanocrystalline structure in which the atoms arrange themselves in nanometer-sized grains to form a crystalline structure. The advantage is that the grain sizes – meaning the areas with the same crystalline structure – can be specifically varied and can be

The researchers use a melt spinning process for the recycling of permanent magnets (Image © Fraunhofer Project Group IWKS) used to change the properties of the permanent magnet. In a further step, the researchers mill the flakes into a powder, which can then be further processed. “We press it into its final shape,” Diehl added. A demonstration plant has already been established. “The demo system can process up to half a kilogram of molten material and is somewhere between a lab and a large-scale plant,” stated Diehl. The researchers are now optimising the properties of the recycled magnets by varying the melt spinning process – such as the speed of the copper wheel or the temperature of the melted material during the rapid solidification process. Both influence the cooling rate and consequentially also the crystalline structure of the solidified material. www.iwks.fraunhofer.de

First plug-in hybrid transmission from ZF enters volume production ZF Friedrichshafen AG has announced that its hybrid drive system, incorporating a compact electric motor and eight-speed automatic transmission, has now entered volume production and will feature in BMW’s X5 xDrive40e. Vehicles can now be driven purely electrically with zero local emissions over comparably long distances and significantly faster, stated the company. As a result, the standard cycle according to ECE 101 shows fuel reductions of up to 70% depending on the capacity of the battery system. The BMW X5 will be the first model to feature the new ZF plug-in hybrid in volume production.

“Electrifying the driveline is an essential means for ZF to further increase efficiency and significantly reduce emissions,” stated Dr Stefan Sommer, CEO of ZF Friedrichshafen AG. “As plug-in hybrid vehicles become more prolific, consumers are exposed to the performance capability of hybrid technology in general, for which we expect demand to increase for a long time, and our plug-in hybrid transmission in particular. It makes individual mobility more environmentally friendly, more dynamic and also more sustainable and is completely suitable for everyday use at the same time.”

Despite its compact dimensions the electric motor is stated as being very strong, providing a maximum power of 83 kW (113 HP) and a torque of 250 Nm from a standstill. This allows the vehicle to be driven purely electrically at a speed of up to 120 km/h and within a range of 31 km. The electric motor is integrated fully into the transmission housing and is cooled by atomised oil. www.zf.com

Winter 2015

Powder Metallurgy Review

Industry News

Sacmi supplies new Rare-earth magnet substitutes hydraulic press to developed at Masdar Institute PM parts maker Researchers from Masdar Institute of “Rare-earth metals are used in Science and Technology in Abu Dhabi, many applications requiring strong Schunk Press manufacturer Sacmi, based in Imola, Italy, has announced that Schunk Sintermetalltechnik GmbH recently installed one of the company’s MPH 200 hydraulic presses at its facility in Thale, Germany. Sacmi stated that this is the first solution of this type to be installed by Schunk, a specialised Powder Metallurgy parts maker supplying precision components to the automotive industry. The MPH 200 press allows the user to make items of complex geometry and ensures a dimensional accuracy up to ± 0.025 mm. The press has a compact configuration that lets users perform all the necessary quality control tasks at high speed and directly in-line. Located at the high end of the market in terms of performance, states Sacmi, the press offers high precision, reliability and outstanding productivity. Sacmi has over twenty years’ direct experience in the metal powder field and over 40 years in hydraulic systems. The company’s range of MPH presses are claimed to be technologically advanced yet simple, safe and highly reliable. The press design can include either standard multi plate technology or advanced systems such as the patented floating table and the tool-holder adapter with concentric plates. www.sacmi.com

Powder Metallurgy Review

UAE, are developing novel, low-cost magnets with improved magnetic properties that can withstand high temperatures to replace expensive rare-earth magnets commonly used in automotive, aerospace, military and energy industries. “The novel magnetic materials that Masdar Institute researchers are discovering could support the development of next-generation clean energy technologies, including wind turbines, and have the potential to impact many other key economic industries that rely heavily on strong permanent magnets, including aerospace and defence,” stated Dr Behjat AlYousuf, Interim Provost, Masdar Institute. “Currently, each megawatt of power generated by a wind turbine requires up to one ton of rareearth magnets. Our research aims to develop alternative, low-cost magnets that can reduce the cost of wind turbines,” stated Dr Mamoun Medraj, Professor, Materials Science and Engineering, Masdar Institute. Dr Medraj and Post-Doctoral Researcher Dr Ahmad Mostafa are leading the research. Medraj believes the magnets they are developing will be significantly cheaper and have greater thermal stability than neodymium based magnets, which are the strongest rare-earth magnet used today, making them well-suited for demanding, high-temperature applications such as the power and automotive industries. They also can provide the UAE with a potentially high-value product in the form of cheaper magnets. “The problem with neodymium magnets is that they are only good up to 150°C. After that, they demagnetise. While our magnets might not have the same amount of magnetic energy as neodymium magnets, it is more thermally stable and cheaper in price,” Medraj explained.

Winter 2015

permanent magnets, such as electronics, motors, wind turbines and many other high-tech applications,” added Medraj. “While the entire world has become dependent on these hightech magnets, over 95% of the global production of rare earth materials currently occurs in China. This creates a supply risk for many reasons.” Medraj began his pursuit of cheaper, high-tech magnets that do not rely on expensive rare-earth metals while at Concordia University in Canada, where he worked for 13 years. He brought his innovative research to Masdar Institute a year ago and has been rapidly discovering new magnetic materials since. In order to discover new combinations of various elements that produce magnetic phases, scientists would try to combine and test different amounts of various elements. This method, however, is extremely slow and can take several years, as potential combinations are unlimited. Medraj’s method speeds the process up to a couple of months. “We have successfully discovered new magnetic phases within different systems and are now in the process of characterising their magnetic properties,” Medraj stated. The high throughput screening process developed by Medraj combines thermodynamic modelling and continuous diffusion – experiments in which two or more elements are continuously diffused, or combined, at varying amounts. The continuous spectrum formed, which represents the various element combinations, is analysed and a magnetic force microscope is used to determine if any magnetic phases exist. The newly discovered magnets, along with the innovative method used to develop them, could result in significantly cheaper and more efficient sustainable technologies. www.masdar.ac.ae

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Industry News

GKN demonstrates prototype metal hydride storage tank GKN Sinter Metals, in Bonn, Germany, recently demonstrated its development of hydrogen storage systems, incorporating metal hydride structures produced by Powder Metallurgy, to Germany’s North-Rhine Westphalian Minister of Economic Affairs, Garrelt Duin. Metal hydrides provide a safe and efficient solid state approach to hydrogen energy storage. During his visit, Minister Duin was able to inspect a prototype of a hydrogen storage tank developed by GKN together with a partner company. The pilot tank features metal hydrides made of structures produced by Powder Metallurgy. “Hydrogen will play a central role in low-emission energy supply in the future and this is why GKN is working intensively on this trend,” stated Guido Degen, GKN’s Senior

Vice President Business Development & Advanced Technology - Powder Metallurgy. “We are again demonstrating our leadership in innovation and fully utilising GKN’s competencies in material and production techniques to bring this pioneering technology to full production-readiness,” added Degen. www.gknsintermetals.com

Minister Duin and GKN management team during a tour of GKN Sinter Metals Bonn

Höganäs boosts its Digital Metal capacity Höganäs AB, Sweden, has announced further investment in its Digital Metal facility with the addition of a new sintering furnace to increase output of its 3D printed metal components. The additional capacity was required to meet the growing demand for 3D printed components and offer material alternatives, the company stated. “The new furnace has significantly increased our production capacity and we are also able to sinter a wider range of metal powders,” stated Ralf Carlström, General Manager for Additive Manufacturing at Höganäs. The new high temperature furnace offers variable sintering atmosphere settings and very precise adjustment of temperature profiles, crucial to the sintering of high quality metal components. www.hoganas.com

Updated Freeman Technology website offers support to powder processors Powder characterisation specialist Freeman Technology, based in Tewkesbury, UK, has updated its website with a number of practical resources aimed at engineers, formulators and researchers working in both the metal powders and Additive Manufacturing industries. The website now includes animation that provides an insight into the testing required for improved powder characterisation as well as the company’s eBook series, covering the fundamentals of powder behaviour and testing. The way in which powders behave defines their processability and, in many applications, their value. The new animation clearly illustrates the wide range of variables that can influence powder flow and how Freeman Technology’s FT4 Powder Rheometer can be used to investigate their impact. The resulting data

Powder Metallurgy Review

enables sensitive QC/QA, more efficient powder processing and effective troubleshooting. All three of Freeman Technology’s educational eBooks on the fundamentals of powder behaviour and characterisation are also now available for download. The first ‘An Introduction to Powders’ complements the animation with a detailed discussion of powder behaviour and the factors that influence it. The second and third, ‘Choosing a Powder Tester’ and ‘The Value of Powder Testing’, discuss how to identify the best tester for an industrial application and justify the associated investment. Powder testers vary considerably in terms of their industrial relevance and ability to deliver value and this can have a major influence on the return on investment associated with their purchase. Finally, the literature section of

Winter 2015

New animation from Freeman Technology provides an easy to understand illustration of the mechanisms of powder flow the website has also been updated. This database provides information on powder characterisation for all industries and includes a wide range of published articles, conference papers and white papers. Its ongoing development underlines Freeman Technology’s commitment to understanding powder behaviour and to providing powder processors with up-to-date, relevant information to tackle and solve manufacturing problems. www.freemantech.co.uk

Industry News

New phase-toughened ceramic inserts from Greenleaf Corporation

ASCO Sintering to manufacturer Shift by Wire components for auto sector

Greenleaf Corporation, headquartered in Saegertown, Pennsylvania, USA, a leading developer of cutting tool technology, has announced that its new XSYTIN™-1 phase-toughened ceramic insert grade is now available to complement its range of ceramic insert cutting tools. The company specialises in the manufacturing of high-performance tungsten carbide and ceramic inserts as well as innovative tool-holding systems. XSYTIN™-1 is engineered by Greenleaf to machine more materials than any other ceramic grade in the industry today. It is designed to mill, turn and groove even the most difficult materials on the market at extreme feed rates with the high surface footage of ceramic inserts, stated Greenleaf. XSYTIN™-1 is the strongest ceramic insert grade ever produced by Greenleaf and is stated to be ideal for use in interrupted cuts, removal of scale, roughing, semi-finish and finish cuts in HRSA materials, cast irons, nodular irons, ductile irons, steel alloys and stainless steels. www.greenleafglobalsupport.com

ASCO Sintering Co, based in Los Angeles, California, USA, has announced it will begin supplying a number of new sintered components to a tier one automotive supplier for use in “Shift by Wire” gear systems. The compound gear, output gear, trigger arm, trigger link and couplings are net shape and were custom engineered and produced using a broad spectrum of advanced Powder Metallurgy solutions and materials ranging from copper infiltrated steel, bearing grade steel, 316 stainless steel and sinter hardened steel. ASCO production processes maintain specification and quality levels above 5 sigma for these critical parts that are linked to the performance and safety features of the vehicle’s effortless shifting mechanism. All of the parts have successfully passed PPAP requirements and will be primarily used in luxury higher end vehicles. The Shift by Wire system is becoming increasingly popular with OEMs as automotive companies look for ways to reduce weight, save space, improve reliability and better integrate the drive train and shift mechanisms into increasingly electronic vehicles. www.ascosintering.com

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Winter 2015

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Powder Metallurgy Review

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Powder Metallurgy Aluminium

Powder Metallurgy aluminium components offer lightweight solutions and high volume production Powder Metallurgy aluminium components provide design engineers with a lightweight, energy saving option for a range of applications. The process can offer unique material properties along with the ability to produce high volumes of complex aluminium components. Dr.-Ing. Thomas Schubert and Dr.-Ing. Thomas Weissgärber, of Germany’s Fraunhofer IFAM in Dresden, describe the production process and provide a number of industrial case studies to highlight the possibilities of aluminium PM.

Powder Metallurgy applications of lightweight materials, such as alloys of aluminium and titanium, are of increasing technological and commercial importance. The Powder Metallurgy process offers considerable advantages in the on-going goal to reduce weight in transport applications and thereby save fuel. Currently, however, the applications for titanium PM parts are limited to only a few products, such as automotive engine intakes and exhaust valves [1, 2]. This is primarily due to the high cost of a titanium component arising from the feedstock as well as the manufacturing process. Therefore, cost reduction has been the main thrust of current titanium research and development. Aluminium is the second most commonly used metal, following iron and steel, in global production. The combination of low density (2.7 g/cm3) with excellent formability, machinability and corrosion

resistance makes aluminium alloys attractive for many applications. The conventional press-and-sinter PM route is a relatively efficient and inexpensive process, with demonstrated capability for producing high volumes of complex aluminium components (Fig. 1) with a reasonable degree of

precision [3-5]. Despite the similarity to conventional PM processing of iron-based materials, the sintering of aluminium requires very robust process parameters particularly with regard to tight control of sintering atmosphere, temperature and time of sintering.

Fig. 1 High volumes of PM aluminium camshaft bearing caps are produced by GKN Sinter Metals (Courtesy GKN Sinter Metals)

Winter 2015

Powder Metallurgy Review

Powder Metallurgy Aluminium

Fig. 2 PM aluminium production process [10] (Courtesy GKN Sinter Metals)

Powder production for press-sinter Most of the structural PM aluminium alloys currently used are based on wrought or cast alloy compositions. Materials include ready-to-press

sinter response and provide sufficient mechanical, tribological and physical properties. The aluminium powder used is generally produced by air-atomisation and has a typical average particle size of about 100 µm with an oxygen

“powder blends were developed and designed to both meet an optimum press-and-sinter response and provide sufficient mechanical, tribological and physical properties” powder blends based on 2014, 6061, 7075, Al-14Si and AlMCs (Aluminium Matrix Composite) as well as some developmental materials to meet special customer needs. Fully pre-alloyed powders cannot be used due to their incompressibility and low sintering activity. Therefore, powder blends were developed and designed to both meet an optimum press-and-

Powder Metallurgy Review

content as low as possible (0.2 – 0.3%). All alloying elements are introduced into the ready mixed powders as very fine (typically < 45 µm) elemental metal powders or binary pre-alloyed powders at near eutectic compositions (e.g. AlSi12, AlMg50) containing up to 50% aluminium [6]. In contrast, two commercially available aluminium premixes, the hypere-

Winter 2015

utectic Al-14Si-2.5Cu-0.5Mg alloy and the Al-6Zn-2.5Mg-1.7Cu alloy (in wt.%) developed by ECKA Granules GmbH, Germany, consist of a mix of plain aluminium and a master alloy powder containing all alloying elements [7]. This blend design results in a higher sintering response compared to the traditional blends. Aluminium tends to weld to the die walls during pressing and this requires the addition of a certain amount of pressing lubricant (about 1.5 wt.%), mostly premixed directly with the metal powders. The problems of dusting and segregation of fine powder mixtures can also be obviated by this lubricant addition. The use of ethylenbisstearamide (EBS) is widespread. Most importantly, the lubricant has to be completely removed prior to sintering because any remaining carbonaceous products interfere with sintering. To obtain enhanced control of the debinding step in the continuous furnaces typically used, the atmosphere gas composition has been successfully analysed in-situ by Fourier transform infrared spectroscopy (FTIR) [8, 9].

Sintering technology The Powder Metallurgy manufacturing route, involving uniaxial pressing, dewaxing, sintering and sizing (Fig. 2), allows the near net shape fabrication of precision parts made from many different alloy systems. Sintering is regarded as the most critical step in the aluminium PM manufacturing cycle. Aluminium has a high corrosion resistance due to a thin surface layer of Al2O3. However, this oxide layer prevents the sintering of aluminium powder particles and cannot be reduced during conventional sintering. Successful sintering of aluminium alloys can only be achieved through the formation of a liquid phase, which is able to disrupt the stable oxide skins [11]. Copper is a well-known alloying element for liquid phase activation [12, 13]. The liquid phase sintering mechanism in aluminium alloys involves the

Powder Metallurgy Aluminium

following steps: liquid formation, particle re-arrangement, solution re-precipitation, grain shape accommodation, pore-filling and finally solid state sintering [14, 15]. The conventional sintering mechanism for Al-Cu-Mg, Al-Mg-Si and Al-ZnMg-Cu is sintering with an initial transient liquid phase, which is then transformed to a persistent one at the isothermal sintering temperature. Depending on the selected heating rate and sintering temperature, the variation in ratio of solid to liquid parts also influences the shrinkage. This very sensitive solid/liquid ratio results in high demands to meet the tightly tolerable temperature interval. However, successful sintering of, for instance, Al-Cu-Mg-Si compacts is established industrial practice. Compared to these powder mixtures, the hypereutectic Al-SiCu-Mg, alloy developed by ECKA Granules GmbH, Germany, works in a quite different manner [7]. This is the only known Al-Si commercial pressand-sinter PM alloy with the nominal composition of Al-14Si-2.5Cu-0.5Mg (in wt.%). The incorporated master alloy produces a super-solidus liquid phase with a persistent character, which is very sensitive to oxidation by the ambient furnace atmosphere during sintering. The formation of stable Mg oxide surface layers was revealed in the case of high oxygen partial pressures in the nitrogen atmosphere used. These oxide layers locally hamper the sintering process, resulting in porous surface layers with a consequent reduction in mechanical and wear behaviour. Therefore, the additional control of the oxygen impurities in the furnace atmosphere is important during the sintering of this hypereutectic Al-SiCu-Mg alloy [16]. The mechanism of super-solidus sintering was also adapted to blends based on 7xxx series (Al-Zn-Mg-Cu alloys) [17]. The newly developed premix, referred to as ECKA Alumix 431, offers higher strength and better tensile elongation in the finished parts, due to the higher achievable sinter density compared to the classical powder blends.

Fig. 3 Varying degrees of complexity can be built into aluminium camshaft bearing caps (Courtesy GKN Sinter Metals) The sintering atmosphere is generally an important processing factor for aluminium PM. The best sintered properties of aluminiumbased compacts are achieved by sintering in dry nitrogen, generally evaporated liquid nitrogen [6, 18-21]. A direct reduction of Al2O3 by gaseous nitrogen seems unlikely, but magnesium, even in the small amounts present in aluminium powder, concentrates on the surface of powder particles and enhances sintering by local reduction of Al2O3, prior to the incorporation of nitrogen [22-26]. The formation of aluminium nitride is thereby an additional key effect, whose role for sintering process is not yet completely understood. Obviously, all of these reactions 3 Mg + 4 Al2O3 → 3 Al2MgO4 + 2 Al 2 Al + N2 → 2 AlN may support diffusion processes in aluminium, which could be responsible for the shrinkage observed when a pure nitrogen atmosphere was used.

Camshaft bearing cap The automotive industry is the most lucrative market for PM aluminium, with the production of structural components with remarkable geometrical complexity and high precision. One part which has increased the degree of awareness of sintered aluminium within the automotive market is the camshaft bearing cap, also known as the cam cap [27]. These cam caps have been produced and employed successfully for more than two decades by, for instance, Metal Powder Products Co (MPP) and GKN Sinter Metals. Figs. 3 & 4 show examples of cam caps of varying degrees of complexity made by the PM aluminium process. Alternatively, these components have been manufactured from die cast material, requiring expensive secondary machining to achieve close tolerance features and resulting in

Winter 2015

Powder Metallurgy Review

Powder Metallurgy Aluminium

Rotor and sprocket

Fig. 4 PM Aluminium camshaft bearing caps made by Metal Powder Products Co for General Motors Powertrain [28] (Courtesy MPIF) higher cost. In contrast, the near net shape capability of aluminium PM offers cost savings up to 50%, depending on the geometrical complexity of the part [29]. The alloy most commonly used for cam caps is the PM equivalent of the wrought AA2014. The PM process allows the production of parts with > 90% density, > 200 MPa strength and > 80 HB hardness,

characteristics which are quite sufficient for this relatively lowly loaded application. GKN has developed and begun shipping initial parts made from PM aluminium composites for higher performance applications [30]. One application is a marine outboard cam cap that requires enhanced strength and fatigue properties as well as the exceptional wear resistance.

Aluminium PM has found additional large scale production in automobiles in recent years. The rotor and sprocket used in an automotive cam-phaser application (Fig. 5) are components that are being manufactured from aluminium powder metal [6, 31]. Schwäbische Hüttenwerke GmbH (SHW) has developed and established the conventional press-and-sinter route to produce a PM aluminium chain sprocket and rotor for selected BMW and Porsche cam-phaser systems. The company uses a hypereutectic aluminium-silicon alloy, referred to as Alumix 231, manufactured by ECKA Granules GmbH, Germany. The nominal composition of this commercial press-and-sinter PM alloy corresponds to Al-14Si-2.5Cu0.5Mg (in wt.%). The resulting parts have a sintered density of 2.65 g/cm3 and a relatively homogeneous microstructure. After heat treatment, the components have a tensile strength of up to 350 MPa, hardness of >100 HB and elongation of 0.5-0.6%. Compared to a standard sintered iron cam-phaser design, weight is reduced from 900 g to 450 g. Additionally, fuel saving is delivered due to the reduced weight and rotating inertia is also reduced, improving the dynamic response behaviour of the cam-phaser, and thus providing another benefit to engine performance and efficiency. These products are now routinely fabricated in annual volumes in excess of 106 units per year.

Connecting rods

Fig. 5 PM aluminium VCT sprocket and rotor (Courtesy Schwäbische Hüttenwerke (SHW) GmbH)

Powder Metallurgy Review

Winter 2015

Hitachi Powder Metal Co., Ltd. (now a subsidiary of Hitachi Chemical Co., Ltd.) has developed a powder mixture with the nominal Al-12Si-3Cu-0.5Mg0.15Ni (in wt.%) alloy for sinter-forged connecting rods of general purpose engines nearly two decades ago. As a result, 30% thinner and 50% lighter con rods could be produced, compared with conventional die cast rods. The production process

Powder Metallurgy Aluminium

comprises several processing steps: powder compaction, dewaxing at 400°C, super-solidus sintering (N2, 550°C, 80 min.), closed die forging to 100% relative density (400°C, 700 MPa), heat treatment (470°C, 1h, N2), water quenching and aging, blasting and machining. The following material properties are achieved: Rm = 335 MPa, Rp0.2 = 300 MPa, A5 = 2.5%, hardness HB = 65-75, fatigue strength = 170 MPa (N = 107) [32]. The material offers double the contact stress limit and fatigue strength in a connecting rod, compared with the conventional die-cast aluminium products made from, for instance, AlSi15. The distribution and size of silicon particles in the microstructure have a significant influence on the wear behaviour of the material. An optimum silicon particle size of 25-30 µm was adjusted during the processing. Recently, Hitachi has developed a new pre-mix powder, based on Al-Zn-Mg-Cu, referred to as Alumix 431 and manufactured by ECKA Granules GmbH, Germany, aimed at the substitution of connecting rods made from the aluminiumforged alloy that had already been put to practical use (Fig 6) [33]. High strength is achieved by the Al-ZnMg-Cu matrix material combined with a high wear resistance, achieved by adding chromium boride as hard particles. As a result, the new product has lowered cost simultaneously with a gain in fatigue strength of 18% or more, compared with a general aluminium-forged material.

Heat sinks Apart from net shape, mechanical and/or triobological properties, aluminium PM parts can also be selected because of their high thermal conductivity, which is necessary for thermal management applications. During recent decades, the rapid evolution of integration technology has resulted in a significant increase in electronic device density and speed and such

Fig. 6 Examples of sinter-forged PM aluminium connecting rods [33] (Courtesy JPMA)

Fig. 7 Examples of PM aluminium heat sinks (Courtesy GKN Sinter Metals) a rate of increase is expected to continue for the near future. With such progress, problems arise with heat generation on the semiconductor chips. Actually, more than 50% of electronic failures are caused by insufficient cooling. To achieve long life and reliable performance of these components, it is necessary to keep the operating temperature of an electronic device within specified limits. Therefore, the effective thermal management is a key issue

for packaging of high performance semiconductors. A heat sink or heat spreader is a device that enhances heat dissipation from a hot surface, the most typical case being heat generated by components. The heat sink keeps the device temperature below the specified maximum allowable temperature. Copper or aluminium are the traditionally used materials in air cooling of electronic components, since they offer a solution in reducing the thermal problems.

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Powder Metallurgy Review

Powder Metallurgy Aluminium

GKN has developed new PM Al-Mg-Sn alloys with high thermal conductivity, in the range of 200–250 W/m-K, for heat sink applications [34]. The combination of low cost and high thermal conductivity, while being able to provide the shape and dimensional capability of PM, is attractive to engineers and designers. These new Thermal Series of lowalloyed sintered aluminium materials offer greater design freedom vs. conventional die cast and extruded products, while eliminating the need for machining (Fig. 7). At high power levels, and particularly in applications involving multiple prolonged on/off cycles, however, problems are seen with the reliability of substrate-to-baseplate attachments in high current power modules. Specifically in thermal cycling conditions, the mismatch in coefficient of thermal expansion between the ceramic substrates or semiconductors of the electronic devices and the copper or aluminium baseplates results in high shear stresses at the solder joints. A solution to this problem involves further enhancements through the use of

ceramic additions (e.g. SiC or AlN) to tailor the CTE (Coefficient of Thermal Expansion) and to increase the mechanical strength and stiffness of the heat sink material. Potential markets for sintered aluminium are seen in following applications [34]: • Transmission Control Modules • LEDs • Hybrid vehicles • Electronic Steering Modules • ECU/ECM • IGBT modules • RF Packages • High Power/High Heat applications.

Summary The continuing interest in lightweight materials, combined with the need for cost efficiency, has provided a significant opportunity for aluminium PM, particularly in the automotive industry. There exists the potential for the aluminium PM industry to capture additional market share by replacement of PM iron parts or cast aluminium. New PM alloys are being developed that utilise the advantages

of net shape manufacturing and fine microstructures. For the manufacture of Al-base PM precision parts by pressing and sintering, suitable powder mixtures have been designed. In recent years, remarkable work has been done on Al-Si based sintered alloys or particle-reinforced composites. These materials are attractive for wear loaded components, but also offer good mechanical properties and tailorable CTEs. To date, aluminium PM is still a small part of the overall PM community. Further developments in alloy composition and processing technology, will provide many more opportunities for the application of PM aluminium.

Authors Dr.-Ing. Thomas Schubert and Dr.-Ing. Thomas Weissgärber Fraunhofer IFAM Winterbergstrasse 28 01277 Dresden, Germany Tel +49 351 2537-305 Email: Thomas.Weissgaerber@ ifam-dd.fraunhofer.de www.ifam-dd.fraunhofer.de

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References [1] T. Saito, The automotive application of discontinuously reinforced TiB-Ti composites, JOM 56 (2004) 33-36. [2] M. Qian, Cold compaction and sintering of titanium and its alloys for near-net-shape or preform fabrication, Int. J. Powder Metall. 46 (2010) 5, 29-44. [3] Ch. Lall and W. Heath, PM Aluminium Structural Parts – Manufacturing and Metallurgical Fundamentals, Intern. J. of Powder Metallurgy, 6 (2000) 6, 45-50.

of Methods of Adding Copper on the Strength of Sintered Aluminum Copper Alloys, Int. J. Powder Metall. 4 (1968) 37-47. [13] W. Kehl, H.F. Fischmeister, Liquid Phase Sintering of Al-Cu Compacts, Powder Metall. 23 (1980) 3, 113-119. [14] R. M. German, Liquid phase sintering (New York: Plenum Press) 1st ed., 1985, p. 1 [15] T. B. Sercombe, Non-conventional sintered aluminium powder alloys, Ph.D. Thesis, The Queensland University, Australia, 1998

[4] P. Delarbre and M. Krehl, Applications of PM Aluminium Parts Materials and Processing Schemes”, Proc. 2nd International Conference on Powder Metallurgy Aluminium Light Alloys for Automotive Applications, Troy, 2000, 33-40

[16] Th. Schubert, S. Müller, T. Weißgärber, B. Kieback, Sintering and Age-Hardening of a Hypereutectic Aluminium-Silicon PM Alloy, Proc. of PM2012 - Powder Metallurgy World Congress & Exhibition Yokohama, October 14th - 18th, 2012

[5] S. Huo, B. Heath and D. Ryan, Applications of Powder Metallurgy Aluminium for Automotive Valve-Trains, SAE Int. J. Mater. Manuf. April (2009) 1, 511-515

[17] J. Gradl, H.-C. Neubing and A. Müller, Improvement in the Sinterability of 7xxx-based Aluminium Premix, Proc. EuroPM2004 – Powder Metallurgy World Congress & Exhibition, Austria, October 17th-20th, 2004, vol. 4, 13-20

[6] H.C. Neubing, Sinteraluminium – Der konsequente Weg vom Pulverprodukt zum Leichtbauteil, Proc. Hagener Symposium, FPM, 2004, 3-29 [7] H.C. Neubing, J. Gradl, and H. Danninger, Sintering and microstructure of Al-Si PM components, in World Congress on Powder Metallurgy & Particulate Materials, Advances in Powder Metallurgy & Particulate Materials (2002), 128-138 [8] P. Quadbeck, A. Strauß, S. Müller and B. Kieback, Atmosphere Monitoring in a Continuous Sinter Belt Furnace, to be published in Journal of Processing Technology [9] P. Quadbeck, B. Schreyer, A. Strauß, T. Weißgärber, B. Kieback, In-Situ Monitoring of Gas Atmospheres During Debinding and Sintering of PM Steel Components, Proc. Powder Metallurgy World Congress & Exhibition. PM2010, Florence, Italy 10-14 October 2010, vol. 2, 239-245 [10] GKN Sinter Metals, PM Aluminium Materials brochure, Rev 1.0 [11] S. Storchheim, Aluminium Powder Metallurgy Finally Made Commercially practical, Progr. Powder Metall. 18 (1962) 124-130. [12] T. Watanabe, K. Yamada, Effects

[24] K. Kondoh, A. Kimura, Y. Takeda, R. Watanabe, in: Solid-state Sintering of Aluminium Alloy Powder and Characteristics of Sintered Material, Proc. Conference ‘Sintering’05’, Grenoble, 2005, 335-338. [25] R.N. Lumley, T.B. Sercombe, G.B. Schaffer, Surface oxide and the role of magnesium during the sintering of aluminium, Metallurgical and Materials Transactions A, 30A (1999) pp. 457-463. [26] T. Pieczonka, Th. Schubert, S. Baunack, B. Kieback, Dimensional Behaviour of Aluminium Sintered in Different Atmospheres, Materials Science and Engineering A 478 (2008), 251–256 [27] J.E. Foss and D. DeFranco, The Northstar Cam Bearing Caps: A new Application for Aluminum PM, SAE International Congress and Exposition, SAE Inc., Warrendale, PA, 1994, Technical paper # 940429 [28] P.K. Johnson, 2006 PM Design Excellence Awards Competition Winners,” Intern. J. of Powder Metallurgy, 42 (2006), 4, 17-21.

[18] J.H. Dudas, W.A. Dean, The Production of precision Aluminum PM parts, Int. J. Powder Metall. 5 (1969)2, 21-36.

[29] http://www.metalpowder.com/ engineering-solutions/cam-caps

[19] W.J. Huppmann, Sintered aluminium parts for automotive applications, Proc. 7. Int. Leichtmetalltagung, Leoben-Wien, 1981, 236-237.

[31] A. Pohl, High Wear Resistant Parts of Sintered Aluminium for the Automotive Application, Proc. Euro PM2005 - Powder Metallurgy Congress & Exhibition, October 2nd-5th, 2005, Prague, 199-204

[20] H.C. Neubing, G. Jangg, Sintering of aluminium parts: the state-ofthe-art, Metal Powder Rep. 42 (1987) 354-358. [21] M. Qian and B. Schaffer, Sintering of aluminium and its alloys, in Sintering of advanced materials – fundamentals and processes, ed. by Z.Z. Fang, Woodhead Publ. Ltd., 2010, Part III/12, 291-323 [22] A. Kimura, M. Shibata, K. Kondoh, Y. Takada, M. Katayama, T. Kanie, H. Takada, Reduction mechanism of surface oxide in aluminium alloy powders containing magnesium studied by X-ray photoelectron spectroscopy using synchrotron radiation, Appl. Phys. Letters 70 (1997) 26, 3615-3617.

[30] http://www.gkn.com/sintermetals/ capabilities/aluminium-pm/news

[32] Z. Ishijima, H. Shikata, H. Urata, S. Kawase, Development of PM forged Al-Si Alloy for Connecting Rod, Adv. Powder Metallurgy and Particulate Mat., 4 (1996), 14-3 – 14-14 [33] JPMA 2007 New Materials Category Prize Winner, Hitachi Powdered Metals Co Ltd, JPMA, Japan [34] R. L. Hexemer Jr., I.W. Donaldson, L.B.J. Smith and D.P. Bishop, Development, properties, and applications for a High Thermal Conductivity Sintered Aluminium Material, Proc. of Advancements in Thermal Management Conference 2012 held 18./19. September 2012, Denver, Colorado, USA, 123-134

[23] K. Kondoh, A. Kimura, R. Watanabe, Effect of Mg on sintering phenomenon of aluminium alloy powder particle, Powder Met. 44 (2001) 2, 161-164.

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Euro PM2015: Enhancing the PM process

Euro PM2015: Technologies for enhancing the Powder Metallurgy process A series of papers presented at the Euro PM2015 Congress, held in Reims, France, October 4-7, 2015, looked at the development of a number of design tools for improved control of conventional press and sinter Powder Metallurgy processes. These papers were included in a technical session specifically dedicated to presenting “Tools for Improving PM”. Dr David Whittaker reports on this session for Powder Metallurgy Review and highlights the key developments in this area.

Master alloy additions The first of the papers presented in the ‘Tools for Improving PM’ technical session was one of six keynote papers in the congress and related to the tailoring of the composition of master alloy additions. Particular reference was made to the effects of introducing oxidation-sensitive elements and of varying the solubility of the base iron in the generated liquid phase during sintering. The paper was presented by Raquel de Oro Calderon (Technical University of Vienna, Austria) and was co-authored by Christian Gierl-Mayer and Herbert Danninger (also Technical University of Vienna) and Elena Bernardo, Monica Campos and Jose Torralba (Universidad Carlos III de Madrid, Spain) [1]. The master alloy route first emerged during the 1970s as a means of introducing elements

with high oxygen affinity into low alloy sintered steels. The combination of these elements with other elements with a lower sensitivity for oxygen, such as Fe, reduced the risk of oxidation during the early stages of sintering. The master alloy route

also conferred a number of other advantages, such as preserving the compressibility of the base powder and yielding flexibility in the selection of the final composition by using combinations with different base powders. However, one of the most

Fig. 1 A busy exhibition accompanied the Euro PM2015 Congress sessions (Courtesy EPMA)

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Powder Metallurgy Review

Euro PM2015: Enhancing the PM process

MA1

Cu-2Ni-1Si (wt.%), Fraction <45 μm Tsolidus= 1073°C, Tliquidus=1091°C, Tsintering= 1120°C

MA2

Ni-4Cu-12Si (wt.%), Fraction <45 μm Tsolidus= 1084°C, Tliquidus=1127°C, Tsintering= 1250°C

MA3

Fe-40Mn-15Si-1C (wt.%), Fraction <45 μm Tsolidus= 1060°C, Tliquidus=1072°C, Tsintering= 1250°C

Table 1 Characteristics of the powdered liquid phase promoters used in this study. Tsintering represent the expected sintering temperature. Tsolidus and Tliquidus were measured by DTA (in Ar) [1] interesting benefits of using master alloys is the fact that their composition can be specifically designed for the particular purpose of forming a liquid phase that enhances the distribution of alloying elements and accelerates the sintering mechanisms. Working with a liquid phase

does, however, introduce important challenges, such as maintaining proper dimensional control and minimising the effect of secondary porosity on the final performance of the steel. Over the past decade, the use of thermodynamic and kinetic soft-

ware tools has triggered interesting developments in the design of liquid phases, by allowing the identification of low melting point compositions. The author has previously reported on advances in the design of master alloy compositions that present a methodology for prediction, from the early stages of the design, important features of the liquid such as its wettability, infiltration capability and dissolutive character. In the work reported in this paper, three different master alloy systems were compared, a low dissolutive Cu-based master alloy (MA1) and two systems (MA2 and MA3) with a higher degree of iron dissolution but different contents of oxidationsensitive elements. The compositions and melting temperatures of these

Low Dissolutive Cu

1080°C

1085°C

1095°C

Tsintering=1120°C

Low Dissolutive MA1

1075°C

1085°C

1095°C

Tsintering=1120°C

High Dissolutive MA2

1090°C

1100°C

1120°C

Tsintering=1250°C

High Dissolutive MA2

900°C

1185°C

1195°C

Tsintering=1250°C

Fig. 2 Microstructure evolution in steels containing Fe+0.5 wt. %C with 4wt.% addition of Cu, MA1, MA2 or MA3. Experiments in static He atmosphere [1]

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Euro PM2015: Enhancing the PM process

Technique

Equipment and Characteristics of the experiment

Thermodynamic Calculations

ThermoCalc® software. Databases: TCFE5 for Fe based master alloys, and SSOL4 for Ni and Cu based master alloys

Wetting Experiments

DSAHT furnace (KRÜSS) equipped with an observation window and a recording system. Atmospheres: Ar and N2-5%H2 (Purity 99.9%). Videos recorded during continuous heating at 5°/min heating rate up to 1200°C

STA: Differential Thermal Netzsch STA 449 C Analysis and Thermogravimetry Experiments in Ar atmosphere. 1500°C, Heating/Cooling rate 20º/min Dilatometry

Netzsch 402 C dilatometer Experiments in H2 atmosphere. 1370°C, Heating rate 10º/min

Mass Spectrometry

Quadrupol mass spectrometer Netzsch QMS 403 Aeölos Coupled by a quartz capillary with STA and dilatometer. Allows the analysis of the gaseous species evolved during the thermal treatment

Step Sintering Experiments

DT1000 Adamel Lhomargy quenching dilatometer Atmosphere: He, Heating rate 10°/min, Cooling rate ~ 100°/s

Table 2 Euro Summary of the different experimental equipment and characteristics of the experiments [1] PM2015 Tools for Improving techniques, PM

Fe - 4Cu

Fe - 4MA1 (Cu-2Ni-1Si)

dL/Lo /%

3.5

2.5

Ar 1.9 % 1.8 %

1.5

1.3 % Ar

0.5

2.5

A r 1.9 % H 2 1.9 %

1.5 A r 1.3 % H 2 1.1 %

0.5

1 % H2

-0.5

200

400

600

800

1000

1200

-0.5

Fe - 4MA2 (Ni-4Cu-12Si)

400

600

800

1000

1200

Fe - 4MA3 (Fe-40Mn-15Si-1C) dL/Lo /%

dL/Lo /%

3.5

3.5 Ar 0.79 % H2 0.78 %

2.5 Ar H2

1.5

1.1 % 1%

Ar 0.85 % H2 0.85 %

2.5 1.5

0.5 -0.5

200

Ar 1.2 % H2 1.1 %

0.5 200

400

600

800

1000

1200

-0.5

200

400

600

800

1000

1200

Fig. 7 Dilatometry on green compacts pressed at 600 MPa for samples without graphite. Fig. 3 Dilatometry on green compacts pressed at 600 MPa for samples without graphite. Experiments in Ar and Experiments in Ar and pure H2. pure H2 [1] Fe -0,5C- 4Cu

Fe -0,5C - 4MA1 (Cu-2Ni-1Si)

dL/Lo /%alloys master

dL/Lo /% microstructural

three are given in comparisons of of the alloying elements and very A r 1.6 % 3.5 3.5 here Table 1. MA3 is seen to contain evolution are presented homogeneousAr microstructures. 1.3 % H 2 1.3 % H2 1.3 % a much higher level of oxidation as Fig. 2 and of the observed The excellent infiltration ability of 2.5 2.5 Ar 1.5 % A r 1.6 % H2 1.4liquids sensitive1.5 elements (Mn and Si) Hthan dimensional changes, characterised these causes a significant % 2 1.4 % 1.5 MA2. The experimental techniques, by dilatrometric studies, as shown swelling effect on forming liquid, 0.5 0.5 equipment and characteristics of in Figs. 3 to 5. On the basis of these however. With these types of liquids, -0.5 the experiments, used to study600 the 800 results, the authors -0.5 have proposed the dimensional stability of the parts 200 400 1000 1200 200 400 600 800 1000 1200 effects of using these three master a number of general conclusions, as seems to be more sensitive to those alloy types, are summarised in follows. parameters that affect the wetting Fe -0,5C - 4MA2 (Ni-4Cu-12Si) -0,5C - 4MA3 (Fe-40Mn-15Si-1C) Table 2. Non-dissolutive or lowFe dissolutive behaviour of the liquid, such as the The results liquids (Cu and MA1)dL/Lo have sintering atmosphere or the presence /% a high dL/Lo /% from the full range of experiments can be found by ability to infiltrate and of carbon. 3.5distribute 3.5 reference to the full paper, but the through iron pore skeleton, Liquids with a highly dissolutive Ar 0.43 the % Ar 0.69 % 2.5 2.5 H2 0.53 % H2 Ar 1.5 % significant results in relation to Ar 1.4 % giving 0.48 an%optimum distribution behaviour (MA2 and MA3) tend to 1.5

H2 1.3 %

1.5

1.2 %

0.5

400

600

800

1000

1200

-0.5

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400

600

800

1000

1200

Ar H2

1.5

H2 0.85 %

H2 0.78 %

1.1 % 1%

1.5

0.5

Ar 1.2 % H2 1.1 %

0.5

Euro PM2015: Enhancing the400PM process 200 600 800 -0.5

1000

1200

-0.5

400

600

800

1000

1200

Fig. 7 Dilatometry on green compacts pressed at 600 MPa for samples without graphite. Experiments in Ar and pure H2. Fe -0,5C- 4Cu

Fe -0,5C - 4MA1 (Cu-2Ni-1Si)

dL/Lo /%

dL/Lo /% A r 1.6 % H 2 1.3 %

3.5 2.5

A r 1.6 % H 2 1.4 %

1.5

0.5

-0.5

200

400

600

800

1000

1200

Fe -0,5C - 4MA2 (Ni-4Cu-12Si) Euro PM2015

Ar H2

200

400

1.5 %

1.4 %

600

800

1.3 % 1.3 %

1000

1200

Fe -0,5C - 4MA3 (Fe-40Mn-15Si-1C)

dL/Lo /% for Improving PM Tools

dL/Lo /% 3.5

3.5 Ar 0.43 %

2.5 1.5

1.4 %

1.2 %

0.5

0.5 -0.5

400

600

800

Ar 1.5 % H2 1.3 %

1.5

-0.5

200

1000

Ar 0.69 % H2 0.53 %

2.5

H2 0.48 %

1200

200

400

600

800

1000

1200

Fig. 4 Dilatometry on greenon compacts pressed at 600 MPa for samples graphite. Experiments in Ar and pure H2 [1] Fig. 8 Dilatometry green compacts pressed at 600 MPa for with samples with graphite. Experiments in Ar and pure H2. in particular capability, It is impossible to directly extrapolate the influence of the agents observed its in wetting macroscopic Ar reducing H2 which affect the wetting experiments to the conditions in a green compact. Especially in the caseinofturn the could atmosphere, it sensi2 tivity ofaccess the dimensional stability to should be considered that in a green compact the atmosphere only has limited to the internal 1,8 pore network, and a microclimate is created inside the closed pores. This explains the lack of the processing atmosphere. 1,6 differences when only H 2 is used as a reducing agent. Carbon is therefore an essential additive, on 1,4 one hand because it can promote the reduction by carbothermal reactions even inside the because reduction of more the die filling 1,2 microclimate created inside the isolated pores. And on the other hand Simulating for which higher temperatures are neededwill always be assisted by carbon, which is stable oxides 1 process the most effective reducing agent at higher temperatures. 0,8 0,6 0,4 0,2 0

Fig. 5 Dimensional Change during heating in the temperature range between 1000-1370°C [1] remain locally concentrated around Special attention should be paid the location of the primary master when using master alloys with a alloy particles. Dissolution of the high content of oxidation-sensitive surrounding iron base particles alloying elements. Despite the decreases the liquid’s ability to dissolutive behaviour of MA3, the distribute through the pore network dimensional stability in Fe-C-MA3 CONCLUSIONS and this lead to heterogeneous steels is sensitive to the atmosmicrostructures. In this case, phere. this type of master alloy, -Non- dissolutive or low dissolutive liquids (liquid phases whichWith dissolves only small amounts of iron) present a high ability to infiltrate and distribute through the iron porein skeleton, giving an optimum the final properties could be the differences chemical activity distribution of the alloying elements and very homogeneous microstructures. The excellent expected to be more liquids sensitive to a significant between base iron powders and infiltration ability of these causes swelling effect upon liquid formation. With these of fine liquids, dimensional stability of master the parts alloy seems to be more to those thetypes use of andthe well dispersed powders cansensitive cause an parameters that affect the wetting behavior of the liquid, such as the sintering atmosphere or the master alloy powders in the mix. oxygen transfer from the surface presence of carbon. In contrast to the low dissolutive of the iron base particles to the -Liquids with a highly dissolutive behavior tend to remain locally concentrated around the location of (infiltrating) liquids, dissolutive surface of theiron master alloys. The the primitive master alloy particles. Dissolution of the surrounding base particles decreases its ability to distribute pore network which would leadintothe heterogeneous microstructures. In master alloys through providethe significantly change surface chemistry this case, the final properties could be expected to be more sensitive to the use of fine and well lower dimensional of the master alloy particles can liquids, dispersed master alloy changes powders inupon the mix. In contrast to low dissolutive (infiltrating) formation of the liquid phase. modify the behaviour of the liquid,

Attention was switched from powder 9 design to the numerical simulation of the die filling process in a paper presented by Daniel Schlochet Nasato (Johannes Kepler University, Austria) and co-authored by Stefan Pirker and Thomas Lichtenegger (also Johannes Kepler University) and Christoph Kloss (DCS Computing GmbH, Austria) [2]. In the reported work, a numerical study of the effects of cohesive forces on the formation and stability of cavities or holes in the die filling process was carried out. A consistent and uniform die filling process is always desirable. Heterogeneity during die filling can propagate through the subsequent processes and finally lead to serious product defects, such as cracking, low strength, distortion and shrinkage. A poor initial granule packing can also create “arching” defects. However, it is virtually impossible to measure density gradients and free surfaces of powder beds in the as-filled state. Therefore

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Euro PM2015: Enhancing the PM process

interest is growing in the PM industry in alternative methods for numerically analysing these effects, with the discrete element method (DEM) emerging as the most promising approach. The study began with the generation of experimental evidence showing void formation near to the die walls. Sand grains and metallic powder were tested in a cylindrical die using a vertical pouring methodology. For the sand grains, a non-cohesive sample with particle diameter ranging from 100 μm to 350 μm was first tested (Fig. 6 left). To increase cohesion, 4 wt% of water was then added. Results with this powder sample are shown in Fig. 6 right. The formation of cavities in this sample was noted. These cavities extended, in most cases, by many particle diameters from the near wall. In a second step, metallic powder was then assessed. Fig. 7 left side shows a sample of a non-cohesive powder. A similar behaviour to the dry sand sample was observed, with no cavities being formed in the visible, near wall regions. Fig. 7 middle shows the results with a molybdenum powder sample. The molybdenum powder is very cohesive and has an average diameter of 4.6 μm. In Fig. 7 right, the molybdenum sample is shown from a different angle to show the cavities in more detail. The study was then continued through numerical simulation (using the DEM approach) of powder pouring in die filling, varying process variables (shaking and pouring methodologies) and material properties (degree of cohesion and particle size). In the described analysis, to reduce the number of particles having similar physical behaviour, a coarse graining methodology was adopted and a particle size of 1 mm was used. In the numerical simulations, material was poured into a simple cylindrical die using different values for cohesive forces. Particles were removed in a semi-spherical region with a diameter of 5 particles diameters (Dp) in the bottom region of the

Fig. 6 Sand sample. Dry (left) and wet (right) sample [2]

Fig. 7 Left, CFY powder sample is shown. Centre, molybdenum powder sample. Cavities in the molybdenum sample in detail (right) [2]

Fig. 8 Stable cavity region displayed in detail. Left, particles are displayed in detail. Right, force chains are depicted. Particle bed was cut in the centre plane for visualisation [2]

(a)

(b)

(c)

(d)

Fig. 9 Evolution of porosity with time for different cohesion values. (a) horizontal, (b) vertical, (c) combined in-phase and (d) combined off-phase vibration modes [2]

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Euro PM2015: Enhancing the PM process

Fig. 10 Evolution of porosity with time for different vibration modes. In the left side, cohesion value of 1.2 J/m2 and in the right side cohesion value of 1.6 J/m2 [2]

Fig. 11 Inclined pouring and no internals. Left is the initial state and right is the final state [2]

Fig. 12 Vertical pouring and internals. Left is the initial state and right is the final state [2] cylinder to form a stable cavity. The cylindrical die was then shaken, using a frequency of 200 Hz (F200) and amplitude of 1e-4m (this corresponds to Dp/5).The acceleration force resulting from the shaking process was normalised with respect to local minimum and average force chains in the cavity region. Vertical, horizontal, combined vertical and horizontal movement in-phase (resulting in a vertical inclined movement) and combined vertical and horizontal movement off-phase (resulting in a circular movement) were simulated. The evolution of porosity in the cavity region with time (Fig. 8) was defined through a Monte Carlo integration method. This method consisted of generating a statistically

Powder Metallurgy Review

significant number of points per particle in the region of interest. These points were generated in a random way and porosity was calculated by the ratio of points inside / outside of the particles. Fig. 9 shows the evolution of the porosity with time for the different shaking modes. The worst results were obtained with horizontal shaking (left). Only for 0.1 J/m2 and 0.2J/m2, could the collapse of the cavity be predicted. Fig. 9 right corresponds to a combined off-phase (circular) movement and, for this case, the collapse of the cavity could be demonstrated for cohesion values as high as 1.2 J/m2. In Fig. 10 left, the porosities for cohesion values of 1.2 J/m2 using different shaking

Winter 2015

modes are shown. The collapse of the cavity for the combined off-phase movement and an increase in packing for the combined in-phase are demonstrated. In Fig. 10 right, the porosities for cohesion values of 1.6 J/ m2 are shown. The collapse of the cavity could not be predicted, but an increase in packing for the combined movements was noted. In the die filling process, the effects of different process and material variables in the packing region were evaluated through the simulation of the powder pouring process. Two die configurations were analysed: one consisting of a cylinder without any internal tool elements and the second consisting of this same cylinder but with a small cylinder inside. The external cylinder had a diameter of 50 mm and the internal cylinder a diameter of 20 mm. Both configurations were tested for varied pouring (vertical and inclined), vibration mode (vertical, horizontal, combined in-phase and combined off-phase), particle cohesion and size. The tested die filling configuration can be seen in Figs. 11 and 12. From these results, it can be concluded that inclined pouring has a negative impact on the initial arrangement of the material, with high porosity values. After the shaking process, the porosity is reduced to similar values, on comparing the same variables, for the vertical and the inclined pouring cases. A similar behaviour was seen in the case with the internal tooling element and is more pronounced in the higher cohesion cases. This can be explained by the formation of stable heaps of material (Fig. 11), which leads to an uneven distribution of material in the die region. When comparing the shaking modes, it was noted that, for lower cohesion cases, the vertical and horizontal vibration resulted in lower porosity, in comparison with the combined (in-phase and off-phase) vibrations. On the other hand, for the high cohesion case, the combined (in-phase and off-phase) vibrations led to significantly lower porosity.

Euro PM2015: Enhancing the PM process

The region near the small internal cylinder was also investigated. Fig. 13 shows the porosity values for low cohesion (0.2 J/m2). Fig. 13 left corresponds to vertical pouring and Fig. 13 right corresponds to inclined pouring. Fig. 14 shows the porosity values for intermediate cohesion (0.4 J/m2). Fig. 14 left corresponds to vertical pouring and Fig. 14 right side to inclined pouring. The results are very similar to those for the large cylinder porosity with respect to the shaking modes. Overall, the simulation results showed a correlation between shaking mode, pouring method and material properties and the conclusion was drawn that one should consider the combination of the process variables and material properties when optimising the die filling process to reduce material density gradients.

Fig. 13 Low cohesion case. Porosity was calculated near the small cylinder region. Left corresponds to vertical pouring and right side corresponds to inclined pouring [2]

Monitoring of shrinkage during the sintering process

Fig. 14 High cohesion case. Porosity was calculated near the small cylinder region. Left corresponds to vertical pouring and right side corresponds to inclined pouring [2]

The focus then switched to the sintering process in a paper from Torsten Staab and Andreas Diegeler (Fraunhofer Institute for Silicate Research, Wurzburg and University of Wurzburg, Germany). This paper demonstrated the viability of using a thermo-optical measurement device or optical dilatometer (TOM-AC) to follow sintering shrinkages in a number of powder metallurgical samples of unusual shape. Employing an optical dilatometer having an inspection window of 50 mm in diameter offers the possibility of monitoring changes in the shape not only of several samples at the same time but also at different regions of all samples, for example their width, height or surface. Even though more precise, a conventional dilatometer does not offer these options. TOM-AC, the optical dilatometer employed in this study, consists of a cylindrical vacuum vessel containing a metallic Mo-heater, making measurements under reducing or inert gas conditions

Sample Fused quartz glass

Infrared reflector Telecentric lenses

CMOS camera Halogen lamp Sample holder PID controller

Fig. 15 A schematic view of the thermo-optical measurement device TOM-AC at the Fraunhofer ISC (right) and diode light source with Ulbricht sphere (left): Samples are placed inside a furnace enclosed by a vacuum vessel. This allows for a vacuum of better than 10-5 mbar. The sample is illuminated from the left while the CMOS-camera placed to the right detects its shape [3] possible. The vacuum vessel has two cylindrical openings on the optical axis, which are equipped with optical flanges (quartz glass) located at 180°, allowing the sample to be viewed. Quartz glass is used due to its low thermal expansion and good heat resistance. Employing temperatures below 1300°C (low temperature range), the sample is illuminated from the left, while the CMOS-camera detects the sample’s

silhouette inside the furnace from the right (see Fig. 15). The improved version of TOM-AC has a light source equipped with a diode-array illuminating an Ulbricht sphere and, therefore, the distribution of the light is much more homogeneous than in a previous version. Due to the even illumination with short wave length (blue) light over the whole diameter d = 50 mm of the optical flange, the accuracy was improved.

Winter 2015

Powder Metallurgy Review

Euro PM2015: Enhancing the PM process

Euro PM2015 – Tools for Improving PM

rate has its maximum at about 770°C, when the carbothermic reaction of removing the oxides is most active [5]. The reduction of the oxides – supported by the hydrogen-containing atmosphere – makes the shrinkage possible manifesting in the high shrinkage rate observed at 770°C.

Figure 5: Carbonyl iron sphere heated with 3 K/min up to 650°C, holding for 60min and heating then

1240°C with 2iron K/min: Shrinkage (blue dots) by TOM-AC smoothed values Fig. up 16toCarbonyl sphere heated atrecorded 3 K/min up to and 650°C, held for(orange 60 min line) employing a moving average algorithm. From the smoothed shrinkage curve (orange) the and numerical then heated tohas 1240°C at 2 K/min: Shrinkage (blue dots) recorded derivative been obtained (green dots) and again smoothed by a moving average by (red line). A correction for thermal expansion is done assuming a linear behaviour as recorded up to 500°C. TOM-AC and smoothed values (orange line) employing a moving average algoIV. From METALLIC FOAM: STAINLESS STEEL curve (orange) the numerical derivative rithm. the smoothed shrinkage has Inbeen obtained (green dots)ofand again by aofmoving average this section we present an example metallic foam smoothed samples consisting 430L X6Cr17 stainless (red powder. The large porosity of the sample can be seen from figure 4 – middle – by the light line).steel A correction for thermal shining through the sample’s edges. expansion is done assuming a linear behaviour, No shrinkageup wastodetectable up a temperature of 1050°C. However, significant shrinkage occurred as recorded 500°C [3]to 1180°C Euro temperatures PM2015 – Tools Improving PMthe maximum of the shrinkage rate is observed just before at higher andfor around the holding time is reached at 1250°C (shown in figure 6). As described in the previous section, the shrinkage curve has been smoothed and the derivative taken to obtain the shrinkage rate, which worked – as shown in figure 6 – even for the very irregular shape of the metallic foam. The principal trends of shrinkage and shrinkage rate are very similar to those data for the same material taken in a conventional dilatometer – see e.g. [6].

Figure 5: Metallic foam sample consisting of 430L X6Cr17 stainless steel powder: The shrinkage Fig. 17 curve Metallic consisting X6Cr17 stainless powder: shown foam is for a sample width window in the middleofof 430L the sample. The heat treatment steel employed a graphite heater under Ar-gas containing 6.5% hydrogen. We did not apply any correction for thermal The shrinkage curve shown is for a width window in the middle of the sample. expansion. The heat treatment employed a graphite heater under Ar containing 6.5% V. SCREEN PRINTED STAINLESS STEEL hydrogen. No correction for thermal expansion was applied [3] Euro PM2015 – Tools for Improving PM Here, we present our investigation on screen printed grids from stainless steel (316L). De-binding has been performed with a heating rate of 3 K/min inside a separate furnace in three steps under nitrogen containing 5% hydrogen: 300, 500 and 650°C with employed holding times of 30, 30 and 60min, respectively. The samples were then transferred to the TOM-AC and sintered there under the Ar atmosphere containing 6.5% hydrogen up to 1350°C. For more details of the measurement we refer to [4]. The onset of the shrinkage is about 1050°C while the maximum of the shrinkage rate is found to be at 1250°C. Only few data on shrinkage rates for stainless steel samples exist. However, in [6] chapter 3.4.2 a similar behaviour of the 316L-sample has been found: the onset of shrinkage above 1000°C and a maximum of the shrinkage rate at 1250°C. Hence, we can state the optically recorded data is good enough to allow for a sophisticated data analysis obtaining the shrinkage rate as well.

Figure 6: Shrinkage for a grid produced by a screen printing process of stainless steel measured by

our Shrinkage TOM-AC: Placing windowsby for a thescreen total areaprinting (Fig. 4 - right) the corresponding Fig. 18 fortheameasurement grid produced process from stainshrinkage is obtained. The original area has been normalized to 1. A correction for thermal expansion is done assuming a linear behaviour as recorded up to 500°C. less steel measured using the TOM-AC system. Placing the measurement windows for the total area, the corresponding shrinkage is obtained. The VI. CONCLUSIONS original area has been normalised to 1. A correction for thermal expansion is We have shown for several powder metallurgical samples that the optical detection system for monitoring dimensional changes during the heat has an high enough made, assuming a linear behaviour astreatment recorded upaccuracy to 500°C [3] not only to obtain reasonable shrinkage curves, but also to determine shrinkage rates by numerical derivatives of the shrinkage data. This provides the possibility to use the optical detection of PM samples in, e.g., TOM-AC, where at the same time also a detection of warping during the sintering process is possible.

ACKNOWLEDGEMENTS Powder Metallurgy Review

Winter 2015

We would like to thank the group of Prof. B. Kieback – especially Dr. P. Quadbeck (Fraunhofer IFAM Dresden) for discussions and for providing the powder metallurgical products investigated.

At temperatures higher than 1300°C (high temperature range) the sample is self-luminous and the diodearray is switched off. Fig. 15 shows a schematic of the experimental set-up. Averaging over 150 frames, the software corrects imaging errors, such as noise and thermal flickering, while, at the same time, the exposure time is adapted to the brightness. So, the contrast is enhanced by keeping it within the dynamic range of the CMOS-sensor. Temperature is controlled using a PID controller. All CMOS-camera pictures are analysed in real-time, using software (developed at the Fraunhofer ISC) employing a Monte-Carlo algorithm, to determine the sample’s contour with the smallest possible systematic error. The software records the relative change of the sample’s width or height ε = L/L0 within the chosen windows and also stores the pictures taken. The first sample type reported was a metallic sphere, consisting of high purity carbonyl iron after binder burn-out. The shrinkage and shrinkage rates are shown in Fig. 16. From the smoothed shrinkage curve the numerical derivative has been obtained and again smoothed by a sliding average (9 data points), see Fig. 16. As can be seen, not only was a reasonable shrinkage curve obtained, but also the numerically derived shrinkage rate showed that the onset of shrinkage was just below 600°C, while the shrinkage rate had its maximum at about 770°C, when the carbothermic reaction of removing the oxides is most active. The second set of samples was metallic foams, consisting of 430L X6Cr17 stainless steel powder. No shrinkage was detectable up to a temperature of 1050°C. However, significant shrinkage occurred at higher temperatures and, around 1180°C, the maximum shrinkage rate was observed just before the holding time was reached at 1250°C (Fig. 17). As described previously, the shrinkage curve was smoothed and the derivative taken to obtain the shrinkage rate, which worked even

Euro PM2015: Enhancing the PM process

Water

100

Ar blanket

Mass fraction (weight%)

O-ring seal Argon

Astaloy CrM Test 1

Cathode

Cathode Anode Sample

Mo Si

S Fe

10 0 0.0

Water

2.0

4.0

6.0

Isolator

Fig. 19 A schematic illustration of a Grimm glow discharge source [4]

100

10.0

12.0

14.0

Fig. 20 Depth profile of the surface film on Astaloy CrM powder [4]

Astaloy CrM -Test 1 and 2

316L Test 1

70 O

Mass fraction (weight%)

80 Mass fraction (weight%)

8.0 Depth nm

Mn Mo

Si O

0 0.0

2.0

4.0

6.0

8.0 Depth nm

10.0

12.0

14.0

Fig. 21 Depth profile of the surface film on 316L powder [4]

for the very irregular shape of the metallic foam. The principal trends of shrinkage and shrinkage rate were very similar to published data for the same material, taken using a conventional dilatometer. Finally, stainless steel (316L) screen printed grids were investigated. In previously debound samples, the onset of shrinkage was observed to be at about 1050°C while the maximum shrinkage rate was found to be at 1250°C (Fig. 18). Few published data on shrinkage rates for stainless steel samples exist, but, in one data source, a similar behaviour of the 316L samples has been found; the onset of shrinkage above 1000°C and a maximum shrinkage rate at 1250°C. Overall, the reported work has shown, for several powder metallurgical samples, that the optical detection system for monitoring dimensional changes

0.0

2.0

4.0

6.0

8.0 Depth nm

10.0

12.0

14.0

Fig. 22 Small elemental enrichments at the top of the surface oxide film on 316L powder [4]

during the heat treatment has accuracy high enough not only to obtain reasonable shrinkage curves, but also to determine shrinkage rates by numerical derivatives of the shrinkage data. This provides the possibility of using the optical detection of PM samples in, for instance, the TOM-AC, while, at the same time, the detection of warping during the sintering process is also possible.

Characterisation of surface oxide films The final paper in the ‘Tools for Improving PM’ technical session continued the consideration of sintering issues and was presented by Irma Heikkila (Swerea KIMAB AB, Sweden) and was co-authored by Christer Eggertson and Mats Randelius (also Swerea KIMAB),

Sophie Caddeo-Johansson (Sandvik Coromant, Sweden) and Dimistris Chasloglu (Höganäs AB, Sweden). The surface characteristics of the powder particles play a key role in the processing of powders into consolidated products, not least in sintering where initial reduction of surface oxides is an important consideration, and on the final properties achieved for the material. Characterisation of surface oxide films by techniques, such as XPS or TEM/EDS, provides reliable information on the surface films, but these techniques are timeconsuming and the analysed areas are extremely limited. In this reported study, the potential of depth profile analysis by Glow Discharge Optical Emission Spectroscopy (GD-OES) has been evaluated for Astaloy CrM and 316L powders. The glow discharge source commonly used in depth profiling consists of an anode tube and the

Winter 2015

Powder Metallurgy Review

Euro PM2015: Enhancing the PM process

single atoms into the negative glow, where they are diluted in the argon carrier gas. All the elements at the sample surface are sputtered at the same rate as soon as the equilibrium conditions for the plasma are achieved after the plasma ignition. The quantification of GD-OES signals is relatively uncomplicated, giving quantitative information on the content of several species. GD-OES is able to analyse surfaces varying from a few nanometers to 100 μm. The elemental concentrations range from 0.001 % to 100% (mass fraction). The limitation of the technique is that it lacks lateral resolution. The analytical data is averaged over the area defined by the inner diameter of the hollow anode, typically 4 mm. Depending on the application, this can be an advantage or a disadvantage. In the reported results, it was shown that GD-OES displays a thickness of 5 nm for the oxide film on Astaloy CrM powder. The composition of the oxide film is iron-rich. Also, some chromium is present in the surface oxide (Fig. 20). The measured thickness of the oxide film on 316L powders is 3 nm. The oxide film is composed of iron, manganese, chromium and silicon (Fig. 21). The technique can reveal small elemental enrichments at the top of the surface oxide film (Fig.22). The measured area is 12.56 mm2 and the analysis time just a few minutes. Therefore, it was concluded that the method could become a powerful tool in defining averaged information on the chemistry and thickness of surface films in powder

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materials. However, more investigation is needed before GD-OES depth profiling can be fully established as a surface analysis method for powder materials.

Author David Whittaker DW Associates 231 Coalway Road, Wolverhampton WV3 7NG, United Kingdom Tel: +44 (0)1902 338498 Email: whittakerd4@gmail.com

References [1] Tailoring Master Alloys for Liquid Phase Sintering: Effect of Introducing Oxidation-Sensitive Elements, R de Oro Calderon, C Gierl-Mayer, H Danninger, E Bernardo, M Campos and J Torralba, as presented at Euro PM2015, Reims, France, EPMA, UK [2] Numerical Simulation of Porosity of Cohesive Powders after Die Filling Process in Dependence of Different Pouring and Shaking Recipes, D Schlochet Nasato, S Pirker, T Lichtenegger and C Kloss, as presented at Euro PM2015, Reims, France, EPMA, UK [3] Thermo-Optical-Measurement Device for Sintering of PM Products under Atmospheric Control, T Staab and A Diegeler, as presented at Euro PM2015, Reims, France, EPMA, UK [4] First Experiences on Characterisation of Surface Oxide Films in Powder Particles by GD-OES, I Heikkila C Eggertson M Randelius, S Caddeo-Johansson D Chasloglu, as presented at Euro PM2015, Reims, France, EPMA, UK

嘀漀氀⸀ ㄀一漀⸀ ㈀匀唀䴀䴀䔀刀㈀㄀㔀

sample to be analysed. The source is generally named a Grimm type of glow discharge lamp (Fig.19). The flat sample is placed perpendicular to the front of the anode tube, which is kept at ground potential. Electrical power is supplied directly to the sample. A distance of about 0.1-0.2 mm is kept between the sample and anode tube. Sufficient vacuum tightness is achieved by an O-ring, which separates the discharge chamber from the air environment. When the plasma is ignited inside the plasma chamber, free electrons and a plasma are generated. Both species will move freely in the electrical field controlling the plasma chamber and will influence the electrical field through creation of local charge distributions. Different characteristic areas are formed in the plasma. Two of these are fundamental to the use of glow discharge for analytical purposes; namely, the negative glow, free of electrical field but showing high charge density for both ions and electrons, and the cathode dark space. The latter attracts positive ions towards the cathode and generates sample sputtering. The sputtering also sets free secondary electrons, which are accelerated in the electrical field towards the negative glow, where they lose their energy through collisions. During these collisions, the secondary electrons participate in excitation and ionisation processes and thus maintain the plasma. The sputtering process depends strongly on the sample material and its surface properties, but, once the atoms are sputtered, they move as

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Winter 2015

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Additive Manufacturing with Powder Metallurgy June 5–7 • 2016, Boston, MA

Focusing on metal additive manufacturing with powder metallurgy (PM), this conference will feature worldwide industry experts presenting the latest technology developments in this fast-growing field.

Perspectives from: • metal powder producers • toll providers • end users • equipment manufacturers • R&D from academia and consortia Topics will cover: • materials • applications • technical barriers • process economics • new developments Exhibition: • trade show featuring leading AMPM suppliers

Held in conjunction with:

CONFERENCE CHAIRMEN: David K. Leigh, Stratasys Direct Manufacturing Christopher T. Schade, Hoeganaes Corporation For program and further information contact the conference sponsor: Metal Powder Industries Federation 105 College Road East, Princeton, NJ 08540 or visit AMPM2016.org

International Conference on Injection Molding of Metals, Ceramics and Carbides MARCH 7–9 • HOTEL IRVINE IRVINE, CA

Make plans to attend the only international metal and powder injection molding event of the year! MIM2016 CONFERENCE (March 7–9) A two-day event featuring presentations, plant tour and a keynote luncheon • Innovative Processes & Materials • Dimensional Accuracy and Consistency • Advances in Component Uniformity • Part Selection—Best Practices • Leading Process Trends • Tabletop Exhibition & Networking Reception with Representatives from Many of the Leading Companies in the Field ...and Much More!

Optional One-Day Powder Injection Molding Tutorial Precedes Conference (March 7) Taught by Randall M. German, FAPMI world-renowned PIM expert An ideal way to acquire a solid grounding in powder injection molding technology in a short period of time • Introduction to the manufacturing process • Definition of what is a viable PIM or MIM component • Materials selection and expectations • Review of the economic advantages of the process

This conference is sponsored by the Metal Injection Molding Association, a trade association of the Metal Powder Industries Federation

Visit mim2016.org or mimaweb.org for complete program details and registration information

PM Titanium 2015

PM Titanium 2015: Developments in the powder metallurgical processing of titanium PM Titanium 2015, the third in the international series of conferences specifically focussed on the processing, consolidation and metallurgy of titanium, was held in Lüneburg, Germany, from August 31 to September 3, 2015. Dr David Whittaker reports for Powder Metallurgy Review on presentations that discussed the potential benefits of introducing higher levels of oxygen or nitrogen into PM titanium materials, the use of Spark Plasma Sintering in the processing route and the development of a Hydrogen Sintering and Phase Transformation (HSPT) PM method.

The PM Titanium 2015 conference was held at Leuphana University, Lüneburg, close to the city of Hamburg, Germany, from August 31 to September 3 2015. The event was the latest in the series of international conferences focussed on powder processing, consolidation and metallurgy of titanium and follows successful conferences in Brisbane, Australia (2011) and Hamilton, New Zealand (2013). The conference attracted over 130 delegates from 27 countries, and encouragingly for an area of technology where, to-date, the high level of R&D activity has not yet been matched by significant market penetration, several delegates from potential end-users were present, representing the aerospace, biomedical and consumer products sectors. As well as discussing the powder metallurgical processing of titanium, the technical programme also included a number of focussed

sessions on Additive Manufacturing and Metal Injection Moulding. Articles discussing presentations from these sessions can be found in our sister publications Metal Additive Manufacturing (Vol 1 No 3, Autumn/Fall 2015), and Powder Injection Moulding International (Vol 9 No 4, Winter 2015).

Titanium materials with light elements Much attention is often given, in developing PM routes for titanium, to the control of interstitial elements (such as oxygen, nitrogen, hydrogen and carbon) to the low levels speci-

Fig. 1 Participants at PM Titanium 2015 (Courtesy Dr Thomas Ebel)

Winter 2015

Powder Metallurgy Review

PM Titanium 2015

Nitrogen and oxygen content (mass%)

(a) N0

0.8 Nitrogen

0.6

d=13.0 μm

50 μm

0.4 0.2

d=8.2 μm

50 μm

(d) N180

Oxygen

0.0 0

120

180

Treatment time, t/mim

Fig. 2 Dependence of the nitrogen and oxygen contents of SPS Ti powder materials on treatment time in the gas-solid direct reaction [1]

fied in standards for titanium wrought products. In contrast to this preoccupation with their control to low levels, Katsuyoshi Kondoh, Takanori Mimoto, Junko Umeda and Hiashi Imai (Joining and Welding Research Institute, Osaka University, Japan) presented a paper, which extolled the potential benefits of operating at much higher levels of oxygen or nitrogen and developing process

d=7.0 μm

routes to take advantage of the solid solution strengthening benefits available from these alloying elements. The authors identified two effective process routes for the deliberate introduction of oxygen or nitrogen into PM titanium materials: direct reaction between titanium powder and the respective gases and the inclusion of TiO2 or TiN in elemental powder mixes. For example, sintered and extruded Ti samples with oxygen in solid solution were prepared by using an elemental mix of pure Ti powder and TiO2 particles. With an increase in TiO2 addition, X-ray diffraction (XRD) studies showed that the lattice constant in the c-axis of HCP-Ti(α) increased in proportion with the increase in oxygen atoms in solid solution.

Powder Metallurgy Review

It was observed the yield strength increased in proportion with the oxygen content, but any decrease in elongation was, surprisingly, very small. The yield strength increment was in good agreement with calculations, based on the Labusch model, taking into account an observed grain refinement effect. Extruded pure Ti powder material with 1.5 wt% TiO2 had a yield strength of 1025 MPa and

an elongation of 24.8%. Also, a postsintering heat treatment was found to be effective in creating a further improvement in the balance between strength and ductility, because of the complete dissolution of oxygen atoms into HCP-Ti. The reported introduction of nitrogen involved the direction reaction of pure Ti powders in nitrogen gas. Nitrogen can dissolve in Ti to form an interstitial solid solution in large amounts (19 at% in α-Ti). In this study, the content of nitrogen in solid solution in Ti powder was controlled by changing the heat treatment time in a N2 gas flow (gas-solid direct reaction). The treated powders were consolidated into columnar billets having a diameter of 42 mm and

Winter 2015

50 μm

d=6.3 μm

50 μm

Fig. 3 Optical microstructures and mean grain sizes of the extruded Ti powder materials, using pure Ti powder with solute N atoms introduced via heat treatment for 0, 60, 120 and 180 mins in N2 gas atmosphere [1]

“...yield strength increased in proportion with the oxygen content, but any decrease in elongation was, surprisingly, very small.”

(b) N60

1.0

a height of approximately 25 mm using a spark plasma sintering (SPS) system at 1273 K for 30 min in vacuum (~6 Pa). A pressure of 30 MPa was applied in the SPS consolidation. In addition, a hot extrusion process was applied to the SPS billets, using a hydraulic direct press machine. The nitrogen and oxygen contents of each SPS Ti powder sample are presented in Fig. 2. The nitrogen content increased as the treatment time of the process increased. The powder treated for 180 min (denoted as N180 powder) showed the highest nitrogen content of 0.90 mass% in this study, which was a remarkably high nitrogen level compared to those reported in previous studies (up to approximately 0.4 mass%). On the other hand, the oxygen content in all of the SPS samples was almost the same (approximately 0.2 mass%, equal to that of the pure Ti starting powder). It was therefore concluded that the nitrogen content of treated Ti powders and their consolidated samples via the gas-solid direct reaction process is simply controlled by changing the treatment time and not by varying oxygen content. Optical microstructures with average grain sizes (denoted as d in the figure) of the extruded samples N0 (pure Ti starting powder), N60, N120 and N180 are shown in Fig. 3. It can be seen from the N60 (b), N120 (c) and N180 (d) samples that specimens with nitrogen addition via the gas-solid direct reaction process

PM Titanium 2015

0.4720

0.2985

0.4715

0.2980

0.4710

0.2975

c-axis

0.4705

0.2970

0.4700

0.2965

0.4695

0.2960

0.4690

0.2955 0.2950 0.0

a-axis

0.4685

0.5 1.0 1.5 2.0 2.5 Nitrogen content, cN (at.%)

1400 Nominal stress, σ / MPa

0.2990

Lattice parameter, c / nm

Lattice parameter, a / nm

0.4680 3.0

N120

N60

800 600

Pure Ti (N0)

400 200 0

0.1

0.2 0.3 Nominal strain, ε

0.4

Fig. 5 Tensile stress-strain curves for extruded N0/60/120/180 pure Ti powder specimens at ambient temperature [1]

imen was 974 MPa, a 122% increase compared to the pure Ti 0.2%YS of 439 MPa. Improvement in mechanical strength is generally accompanied by a loss of ductility. However, the elongation decreased only from 29.6% to 21.7% in the presented study, indicating that the mechanical strength was remarkably improved with little sacrifice in ductility with the 0.72 mass% nitrogen addition. It was concluded that the extruded Ti-N materials were chiefly strengthened by a solid solution hardening mechanism by nitrogen (as illustrated in Fig. 4). In addition, a second strengthening effect involved grain refinement, created by solute drag (as illustrated in Fig. 3) and this was chiefly responsible for the observed relatively low level of reduction in ductility.

Spark Plasma Sintering A further paper also involved Spark Plasma Sintering (SPS) consolidation in the processing route. This paper, presented by Yongjun Su (Shanghai Jiao Tong University, China) and co-authored by Yifeng Zheng and Delian Zhang (also Shanghai Jiao Tong, University) and Fantao Kong (Harbin Institute of Technology, China), focussed on the microstructures and mechanical properties of a Ti-43Al-5V-4Nb-Y alloy processed by SPS. TiAl alloys are light-weight structural materials, used for high temperature applications such as aero-engine turbine blades, due to their low density and excellent properties, including relatively high yield strength at elevated

3000

-Ti -Al -TiAl3

2500 Intensity (cps)

exhibited almost the same structure as the N0 (a) specimen with an equiaxed α-Ti phase. However, the grain size was refined with the increase of nitrogen content. This is due to the solute drag effect of nitrogen, which prevents grain boundary migration. XRD analysis allowed the correlation of lattice parameters with nitrogen content, as shown in Fig. 4. The interstitial solution of nitrogen atoms in the α-Ti hcp structure caused a considerable expansion on the c-axis, while the a-axis was much less affected by nitrogen content. On the basis of these XRD results, it was concluded that the nitrogen atoms, introduced by the gas-solid direct process, were homogeneously dissolved in the α-Ti matrix. Room temperature tensile testing was carried out in order to assess the mechanical behaviour of the extruded N0/60/120/180 specimens and the stress-strain curves obtained are shown in Fig. 5. Tensile strength was gradually increased when the nitrogen content was raised from 0.52 mass% (in N60) to 0.90 mass% (N180) and offered an outstanding combination of excellent strength and sufficient ductility with the nitrogen addition content of 0.74 mass% (N120). The ultimate tensile strength (UTS) of the N120 specimen was 1120 MPa, an 82% increase over the 617 MPa obtained from extruded pure Ti (N0 with nitrogen content of 0.02 mass%). Moreover, the 0.2% yield strength (YS) of the N120 spec-

Strain rate: 5.0x10-4/s

1000

Fig. 4 Lattice parameter changes in the a- and c-axes of extruded N0/60/120/180 Ti powder specimens, calculated from each XRD profile [1]

N180

1200

2000 1500 1000 500 0 20

100

2theta (deg.)

Fig. 6 XRD pattern of the Ti-43Al-5V-4Nb-Y alloy sample sintered at 650°C under 20 MPa pressure and with a holding time of 5 min [2]

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60000

-Ti -TiAl3

Intensity (cps)

50000

-TiAl -Ti3Al

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-B2

30000 20000 10000 0

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b) 80000

-TiAl

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-B2

50000 40000 30000 20000 10000 0

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-TiAl -Ti3Al

50000 Intensity (cps)

100

-B2

40000 30000 20000 10000 0

60 2theta (deg.)

100

Fig. 7 XRD patterns of the Ti-43Al-5V-4Nb-Y alloy sintered at temperatures of: a) 1200°C; b) 1250°C; c) 1300°C [2]

temperatures, good creep resistance, and excellent oxidation/corrosion resistance. Several methods have been developed for fabricating TiAl alloys such as vacuum arc remelting (VAR), casting and hot working. One of the main problems associated with ingot metallurgy methods is the scatter in the mechanical properties of materials, due to compositional inhomogeneity. Powder Metallurgy is an alternative processing route that can provide better chemical homogeneity and is able to form near net shape products, thus minimising the requirements for post processing machining. Also, PM offers an opportunity to prepare fine-grained components together with better control over chemical and phase compositions. Among the various PM consolidation processes, Spark Plasma Sintering is a promising technique, which involves sintering powders by simultaneously applying a uniaxial pressure and current pulses of high intensity. Some published studies have focussed on the SPS of pre-alloyed TiAl based alloy powders, obtained by atomisation or mechanical alloying, and have shown that it is possible to obtain very fine microstructures. Alloys processed by this route have high strength, but their ductility is still limited. The presented work has therefore assessed the SPS processing of a Ti-43Al-5V-4Nb-Y alloy from a mix of elemental powders. The SPS processing temperature was varied in the range from 650°C to 1300°C. Fig. 6 shows the XRD pattern of the sample which was sintered at 650°C under a pressure of 20 MPa and with a holding time of 5 min. The clear diffraction peaks of the XRD pattern confirm that, when the sintering temperature is lower than the melting point of aluminium (660°C), the sample consists of Ti, Al and Al3Ti phase, suggesting that an interfacial diffusion reaction occurs between solid Ti and Al below the melting point of aluminium. This reaction can be described as: Ti + Al → Al3Ti. Fig. 7 shows the XRD patterns of the samples fabricated at 1200, 1250 and 1300°C, respectively, under a pressure of 50 MPa and with a holding time of 5 min. With an SPS temperature of 1200°C, the sample consists of Ti3Al, TiAl, TiAl3, B2 phases and remnant Ti phase (Fig. 7 a). It has been reported that when the temperature is higher than the melting point of aluminium, an exothermic reaction exists between solid Ti and liquid Al, and that, then, the reactions will occur as follows: Ti

Fig. 8 SEM backscattered electron images of the Ti-43Al-5V-4Nb-Y alloy samples sintered at different temperatures: a) 1150°C; b) 1200°C; c) 1250°C; d) 1300°C [2]

Powder Metallurgy Review

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1200 1000 800 600 400

400

SPS

300 200 100

200 40

60 2theta (deg.)

Fig. 9 XRD pattern of the Ti-43Al-5V-4Nb-Y alloy sample after heat treatment [2]

0.2

0.4

0.6 0.8 Strain (%)

1.0

1.2

Fig. 10 Room temperature stress-strain curves of the samples sintered at 1300°C for 5 min and heat treated at 1300°C for 1 hour [2]

the sample after heat treatment, the compact consists of TiAl and Ti3Al phases and the B2 phase has disappeared. Fig. 10 shows the room temperature engineering stress-strain curves for the samples sintered at 1300°C for 5 minutes with and without subsequent heat treatment at 1300°C for one hour. The sample sintered at 1300°C for 5 min had a tensile yield strength of 396 MPa, a UTS of 461 MPa and an elongation to fracture of 0.7%. The heat treatment at 1300°C for one hour led to an improvement in room temperature yield strength to 527 MPa and a slight improvement of elongation to fracture to 0.8%. This can be attributed to the more complete dissolution of Nb-rich and V-rich particles by the heat treatment, which increases the content of Nb and V in the α2/ɣ lamellae and the disappearance of the B2 phase (as confirmed by XRD analysis).

Controlled hydrogen

Hydrogen Sintering The final paper reviewed in this report was presented by Zak Fang (University of Utah, USA), was co-authored by Matt Dunstan, James Paramore and Mark Koopman (also University of Utah) and described the development of the Hydrogen Sintering and Phase Transformation (HSPT) PM method, capable of delivering wrought-like microstructure and mechanical properties in a Ti-6Al-4V alloy. Powder Metallurgy methods have long been investigated as a means of reducing the cost of titanium alloy production by utilising their nearnet-shape capabilities. However, traditional PM methods produce poor mechanical properties resulting from residual porosity, high interstitial concentrations and a coarse as-sintered microstructure. Therefore, energy-intensive processes, such as pre-alloying the powder,

Vacuum

Vacuum β-Ti sintering

β-Ti sintering

Temperature

+ TiAl3 → Ti3Al + TiAl + TiAl2 and Ti3Al + TiAl2 + TiAl → TiAl. Because the sintering temperature is low and the holding time is short, these reactions are still incomplete. Furthermore, there exists a small amount of B2 phase in the microstructure. The B2 phase is soft at elevated temperatures, due to its bcc structure, and can be deformed more easily than Ti3Al and TiAl. When the sintering temperature is 1250 or 1300°C, the microstructures of the samples are composed mainly of Ti3Al and TiAl and a small amount of B2 phase (Figs. 7b and 7c). Fig. 8 shows the microstructures of samples sintered at 1150, 1200, 1250 and 1300°C, under a pressure of 50 MPa and with a holding time of 5 min. When the SPS temperature was 1200°C, niobium rich particles (Point D) and pores were observed. When the SPS temperature was 1250 or 1300°C, a duplex structure was obtained, but Nb-rich areas still existed in the microstructure as a result of incomplete dissolution. In addition, many small white grains were distributed in crystal and grain boundaries (Figs. 8c and 8d). The results of EDS analyses showed that these small white dots were Y2O3 particles (Point H). Samples sintered at 1300°C for 5 min were also subjected to postsintering heat treatments. Fig. 9 shows the XRD pattern of the sample after heat treatment at 1300°C for one hour. The clear diffraction peaks of the XRD pattern suggest that, in

0 0.0

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Time

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0 20

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500

-Ti3Al

Stress (MPa)

Intensity (cps)

600

-TiAl

(Densification)

Time

(a) HSPT process profile

(b) Vacuum sintering profile

Fig. 11 Sintering profiles of the a) HSPT process, and b) vacuum sintering [3]

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30 μm

5 μm

Fig. 12 SEM micrographs of a) TiH2 vacuum sintered Ti-6Al-4V, and b) HSPT processed Ti-6Al-4V [3]

15 μm

Fig. 13 Optical micrographs of a) bimodal HSPT and b) globular HSPT [3] Condition

UTS [MPa]

σy,0.2%[MPa]

Elongation [%]

As-sintered

994-1024

930-974

13.8-17.8

Bi-modal

1070-1076

981

10.7-11.9

Globular

949-952

872-881

17.6-19.2

982

859

895

828

10.0

HSPT[*]

Vacuum

As-sintered[**] ASTM

B348 (Grade 5 Ti-6Al-4V )[***]

Table 1- Mechanical property comparison of HSPT, vacuum sintering, and ASTM standard B348 for Grade 5 Ti-6Al-4V [3] * J. D. Paramore, Z. Z. Fang, P. Sun, M. Koopman, K. S. R. Chandran, and M. Dunstan, “A powder metallurgy method for manufacturing Ti-6Al-4V with wroughtlike microstructures and mechanical properties via hydrogen sintering and phase transformation ( HSPT ),” Scr. Mater., vol. 107, pp. 103–106, 2015 ** Z. Z. Fang, P. Sun, and H. Wang, “Hydrogen Sintering of Titanium to Produce High Density Fine Grain Titanium Alloys,” Adv. Eng. Mater., vol. 14, no. 6, pp. 383–387, Jun. 2012. *** “ASTM Standard B348-10 Standard Specification for Titanium and Titanium Alloy Bars and Billets,” West Conshohocken: ASTM International, 2010

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pressure assisted sintering and thermomechanical processing (TMP), have been used to reduce porosity and refine the microstructure to produce mechanical properties that can compete with wrought processed Ti alloys. However, these processes eliminate the economic benefit of PM. TiH2 sintering in vacuum has been extensively studied and has been shown to increase densification kinetics and reduce interstitial contamination. However, vacuum sintering of TiH2 produces a coarse lamellar microstructure similar to traditional Ti PM sintering. Therefore, the development of the HSPT process has had the principal aim of producing fully dense titanium alloys with a refined microstructure without utilising energy-intensive powder preparation, exotic sintering methods or TMP. HSPT has therefore been developed as a low cost, mixed elemental, die press and sinter Powder Metallurgy process. To produce the desired alloy composition, powder mixes are prepared from Ti, TiH2 and/or master alloy powders before compaction and sintering. During HSPT, the compacts are sintered in dynamically controlled partial pressures of hydrogen and then subjected to a vacuum anneal (dehydrogenation). Fig. 11 compares the sintering profiles of the HSPT process and traditional vacuum sintering. The HSPT process comprises three main steps. During the first two steps, a dynamically controlled hydrogen partial pressure is utilised to control the hydrogen concentration within the alloy. In the first step, densification is achieved at a temperature above the β-transus. During this first step, the presence of dissolved hydrogen significantly improves densification kinetics, resulting in nearly full densification. The material is then cooled below the β-transus to refine the microstructure via phase transformations in the Ti(alloy)-H system. The final step is a vacuum anneal, or dehydrogenation, at a temperature below the β-transus to remove all residual hydrogen. In comparison, vacuum sintering

PM Titanium 2015

process is the possibility of excess hydrogen content in the as-sintered material, as hydrogen content has a strong influence on fracture toughness and fatigue behaviour of Ti-6Al-4V. As shown in Fig. 11, the last step of the process is to dehydrogenate to remove hydrogen

at 750°C under a rough vacuum (10-1 Pa) using a rotary vane pump. After the prescribed dehydrogenation time, the furnace was backfilled with ultra-high purity argon gas. The samples were then removed from the furnace and quenched in water to prevent the hydrogen concentration

“The ultra-fine microstructure that is formed in the as-sintered state gives rise to excellent mechanical properties for a mixed elemental PM alloy” to a satisfactory level. The ASTM B348 standard requires that the hydrogen content in Ti-6Al-4V should be less than 150 ppm. Another issue is therefore the kinetics of dehydrogenation, which may have a significant impact on the practicality and economics of the technology. In the presented paper, therefore, a series of systematic experiments was conducted to study the dependence of the kinetics on dehydrogenation time and geometry in the last step of the HSPT process. Both experimental data and an empirical model for dehydrogenation were presented. In these experiments, TiH2 powder was cold isostatically pressed, to form cylindrical samples of varying size. These samples were then sintered using the HSPT process described in Fig. 11. Each sample was individually dehydrogenated

profile equilibrating during cooling. Dehydrogenation times were varied from as little as 30 minutes to 24 hours, depending on the sample size. Sample sizes ranged from 9 mm to 40 mm diameter cylinders. After dehydrogenation, each sample was sectioned and chemical analysis was then performed to measure oxygen, nitrogen and hydrogen concentrations. For the concentration profile samples, a 30 mm section was removed from the centre, with radial slices being sectioned for hydrogen analysis. The hydrogen concentration profiles for the large samples dehydrogenated for various times, from 1.25 to 12 hours, are shown in Fig. 14. As the dehydrogenation time is increased, a corresponding decrease in hydrogen concentration and a flattening of the profile is observed. The profiles flatten at roughly 100

Hydrogen Concentration [ppm]

4500 4000 3500 3000

1.25 hr

2500

2.5 hr

Increasing time

incorporates densification and dehydrogenation in one step. Figs. 12a and 12b compare the microstructures of Ti-6Al-4V processed via TiH2 vacuum sintering and HSPT respectively. A distinct difference in the microstructures is observed, with the HSPT process producing an ultra-fine lamellar structure in the as-sintered state. The microstructural refinement that is achieved in the HSPT process results from hydrogen acting as a strong β stabiliser and this, in turn, creates a pseudo-metastable β alloy. On cooling from the sintering temperature, the nucleation and growth of the α phase is suppressed and the α phase precipitates as α and α2 in a fashion similar to β Ti alloys. The ultra-fine microstructure that is formed in the as-sintered state gives rise to excellent mechanical properties for a mixed elemental PM alloy that compete with properties achieved from wrought processing. Furthermore, the ultra-fine nature of the microstructure allows for successful heat treatment to produce wrought-like microstructures without TMP. This ability is unique to the HSPT process and cannot be achieved by vacuum sintering due to the coarse lamellar grains. Figs.13a and b show the microstructures of HSPT samples that have been heat treated using traditional heat treatment methods to produce a bi-modal and a globularised microstructure. Table 1 compares the ASTM standard for quasi-static mechanical properties of Ti-6Al-4V with those achieved by means of TiH2 vacuum sintering and HSPT sintering with as-sintered, bi-modal and globular microstructures. From these data and the micrographs in Fig. 13, it can be seen that HSPT has the capability to tailor the microstructure and produce mechanical properties competitive to wrought processing while avoiding the cost of TMP. Additionally, dynamic testing of HSPT-produced Ti-6Al-4V has demonstrated fatigue strength on a par with wrought Ti-6Al-4V. A significant issue in the HSPT

2000 1500 1000

5 hr 7.5 hr 10 hr 12 hr

500 0

3.75 hr

Radius [mm]

Fig. 14 Hydrogen concentration profiles of the large samples for various dehydrogenation times [3]

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As a final note, it was emphasised that, in the experiments discussed in the paper, a rough vacuum (10-1 Pa) was used to dehydrogenate samples. This absolute pressure created a hydrogen partial pressure corresponding to a minimum (equilibrium) hydrogen concentration around 100 ppm hydrogen. Whist this value is still within the specifications of the ASTM B348 standard for titanium alloys, further experiments have shown that, on using a higher speed pump such as a diffusion or turbo molecular pump, hydrogen concentrations below 10 ppm can be produced.

4500 4000 X Large (40 mm)

3500

Large (22 mm) Medium (13 mm)

H (ppm)

3000

Small (9 mm)

2500 2000 1500 1000

References

500 0

Dehy Time (hr)

Fig.15 Hydrogen concentration at the centre of samples for various samples sizes and dehydrogenation times [3] ppm. Therefore, it was considered likely that this was the equilibrium hydrogen concentration within the sample for the hydrogen partial pressure generated by the roughing pump. In order to have a thorough understanding of the kinetics of dehydrogenation, an attempt to fit a model to the concentration profile was made using a solution of Fick’s Second Law. However, this model relied heavily on the diffusion coefficient of hydrogen in titanium, which was found to vary depending on the degree of dehydrogenation due to phase transformations occurring in the Ti-H system, and, therefore, an empirical equation relating the hydrogen concentration to the dehydrogenation time and overall sample diameter was developed. To develop this empirical equation, the centre concentrations of four sample sizes were measured for varying dehydrogenation times. The results are shown in Fig. 15. From this figure, a logarithmic relationship between hydrogen concentration and dehydrogenation time is observed. To determine the empirical equation, a multiple regression analysis was

Powder Metallurgy Review

performed to include the hydrogen concentration, the natural logarithm of the dehydrogenation time and the sample diameter. A confidence level of 95% was used. The results of this regression analysis are given in the following equation: CH = 1366.94 – 1345.39ln(t) + 91.91d Where CH is the hydrogen concentration at the sample centre in ppm, t is the dehydrogenation time in hours and d is the sample diameter in mms. This equation is particularly useful in an industrial setting, where Ti parts are not uniform in shape. Unlike the theoretical model, which is only applicable to cylindrical bars, the equation provides information on the time needed to dehydrogenate for the largest diffusion length. This makes it applicable to irregular shapes. The equation is also helpful in the determination of the dehydrogenation cost. Dehydrogenation time can vary depending on the sample size and the ability to determine the time required to dehydrogenate a component allows a cost estimation of the HSPT process to be more easily tailored to a specific component.

Winter 2015

[1] State of The Art PM Ti Materials with Ubiquitous Light Elements, K Kondoh, T Mimoto, J Umeda and H Imai, as presented at PM Titanium 2015, August 31 to September 3, 2015 Lüneburg, Germany. [2] Microsturctures and Mechanical Properties of Ti-43Al-5V-4Nb-Y Alloy Consolidated by Spark Plasma Sintering, Yongjun Su, Yifeng Zheng, Delian Zhang and Fantao Kong, as presented at PM Titanium 2015, August 31 to September 3, 2015 Lüneburg, Germany. [3] Powder Metallurgy Ti-6Al-4V Alloy with Wrought-like Microstructure and Mechanical Properties by Hydrogen Sintering, Z Fang, M Dunstan, J Paramore and M Koopman, as presented at PM Titanium 2015, August 31 to September 3, 2015 Lüneburg, Germany.

Author Dr David Whittaker 231 Coalway Road Wolverhampton WV3 7NG, UK Tel: +44 (0)1902 338498 Email: whittakerd4@gmail.com

PM Titanium 2015 Conference Proceedings The full proceedings of the conference will be available in early 2016. For further information contact Thomas Ebel: thomas.ebel@hzg.de

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JPMA Awards 2015

Japan’s automotive industry drives advances in Powder Metallurgy technology The winners of the Japan Powder Metallurgy Association’s (JPMA) 2015 Powder Metallurgy Awards showcase the continuing developments being made to further expand the range of applications for Powder Metallurgy. The demands of the automotive industry for ever more efficient engines continues to require improved mechanical properties and flexibility of design, both of which PM can offer. The winning components in this years awards recognise innovations in new materials, manufacturing processes and component design, not just in the automotive sector, but in a number of other important industries.

Development prize: New design Enhanced cost effectiveness through the reduction of wear resistant material on the valve seat Fine Sinter Co. Ltd. received an award for a modified design concept for valve seats (Fig. 1). This valve seat provided an improvement in cost effectiveness by minimising the amount of highly wear resistant material used through the reviewing of the layer boundary angle. The valve seat has expensive, highly wear-resistant material (seat material) on the seat surface where the valve impacts, because impacting the valve wears the seat. Therefore, in order to improve cost effectiveness, the developed valve seat has two layers with a cheaper material (base material) on the cylinder head side because wear resistance is not required on this part of the component.

This development improved the layer boundary angle to 45 degrees, which is parallel to the valveimpacting surface angle. The amount of expensive material is therefore reduced. Furthermore, a drastic cost reduction is achieved by locating the

highly wear-resistant material on the valve seat without waste because wear progresses parallel to the valve-impacting surface. Moreover, the valve seat needs to have heat conduction performance since the interior temperature of the engine

Fig. 1 These valve seats offer cost savings by minimising the amount of wear resistant material used (Courtesy JPMA)

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JPMA Awards 2015

Fig. 2 A soft magnetic composite core for a rectangular ignition coil (Courtesy JPMA) is becoming higher with the trend towards higher efficiency engines, but the use of highly wear resistant material as the seat material reduces heat conductivity because of the hard layer that includes carbide. Decreasing the proportion of highly wear resistant material improves total heat conductivity and provides a heat reduction effect. This effect contributes to the control of knocking that is caused by the higher temperature of the engine. In addition, machinability of the outer diameter is improved because of the reduction of the area of the highly wear resistant material on the outer diameter, which requires heavy machining. Development of a soft magnetic composite core for high-power output and rectangular-shaped ignition coil Sumitomo Electric Industries Ltd. received an award for the development of a soft magnetic composite core for a rectangular-shaped ignition coil, possessing superior ignitable stability resulting in high ignition energy output (Fig. 2). Due to increasing environmental concerns and a consequent significant focus on fuel economy in the automotive market, there is a growing demand for engines with higher thermal efficiency and lower emissions. The use of technologies such as direct-injection lean burn (thin fuel) and EGR (exhaust gas recirculation)

Powder Metallurgy Review

Fig. 3 Sintered bearing for a linear vibration actuator used in a wearable device (Courtesy JPMA)

is being more widely adopted, due to their improvement of thermal efficiency and suppression of nitrous oxide formation. However, the applications for these technologies are limited because their utilisation can degrade ignitable stability. Therefore, there is a demand for the development of an ignition coil with superior ignitable stability. The key points in this development were: (1) Improvement of the magnetic saturation-resistance that is the characteristic of soft magnetic composites. (2) Improvement of volumetric efficiency. This was achieved via a circular re-design of the crosssectional shape taking advantage of the shape flexibility of the soft magnetic composite core. This type of circular design is difficult to achieve using conventional electromagnetic steel sheet. (3) Achievement of high productivity and cost competitiveness through an automated process from compacting to packing, which is unprecedented in the manufacture of sintered parts. Through these improvements, the company has succeeded in developing a soft magnetic composite core for the rectangularshaped ignition coil possessing superior ignitable stability and resulting in high ignition energy output.

Winter 2015

Development of a bearing for a linear vibration actuator to be used in a wearable device Porite Corporation received an award for the development of a sintered bearing which is used for the linear vibration actuator in a wearable device (Fig. 3). The vibration motor has been mounted on the Pocket Bell since around 1990 and its use has increased in number with the spread of the use of the mobile telephone. Mobile telephones in the world market are transforming into smart phones from feature phones. Also, small, high performance and health-conscious wearable devices with vibration features have entered the market. These wearable devices are thin and curved so that a thin, flat-shape linear actuator is required, rather than the cylinder and coin type actuator which has been the mainstream to date. The company has developed a sintered bearing, which has satisfied the characteristics for a linear vibration actuator (vibration characteristic, low noise, shock resistance). This product required different characteristics from the rotating vibration motor. The radius shape on the inner diameter was formed by special tooling in order to remove a fine burr. Low noise material with a high oil film strength, provided by fine porosity and the use of a high viscosity oil specialised for linear sliding motion, were the keys to success in this development.

ÂŠ 2015 Inovar Communications Ltd

JPMA Awards 2015

The customer was initially considering the fullmachining of a stone bearing, such as Ruby and Sapphire. However, as a result of this development, Porite were able to enter this new market. A set of sintered joints for the motor used in a valve lift actuator Diamet Corporation received an award for the development of a set of sintered joints for the motor used in the valve lift actuator of an SOHC engine (Fig. 4). One of the components has projections and the other has grooves. In combining the projections and grooves, the width between the projections is a critical issue. The compaction tool and the compaction conditions were optimised to minimise the distortion caused by springback. The sintering method and conditions were also optimised to improve the scatter of dimensional changes. As a result, the company has succeeded in developing the set of sintered joints for the motor used in the valve lift actuator and the sizing process has been eliminated. These developments have contributed to the practical use of the new mechanism, improving fuel economy and environmental performance and contributing to the potential for downsizing.

Fig. 4 Sintered joints for the motor used in a valve lift actuator (Courtesy JPMA)

Development prize: New materials An austenitic high heat and wear resistant sintered material for a turbocharger application Hitachi Chemical Co. Ltd. received an award for the development of an austenitic sintered material with excellent heat and wear resistance and for use in the valve bushing in a turbocharger (Fig. 5). The usage of turbocharger in vehicles has been increasing recently. Turbochargers have conventionally been used in diesel engine vehicles, but their usage has now also been expanding in gasoline engines. Since the exhaust gas temperatures in gasoline engines are higher than those in diesel engines, austenitic materials tend to be used as turbocharger parts because of their superior heat resistance. To respond to these requirements a new austenitic sintered material with higher wear resistance has been developed. The technical success of this material rests on the condition of the dispersion of carbides, introduced for wear resistance improvement. On increasing the amount of carbide through an increase in the carbon content, wear resistance can be improved but deterioration of oxidation resistance also occurs because of the lower Cr content in the matrix. On the other hand, it was found that finer carbide could improve wear resistance without oxidation resistance deterioration. Therefore, this technology has been applied in the developed material. As a result, an austenitic sintered material, which was superior in heat and wear resistance to the products of alternative processes, was developed. The developed material has proved to be successful in penetrating the market for turbocharger bushings for gasoline engines.

ÂŠ 2015 Inovar Communications Ltd

Fig. 5 Material with excellent heat and wear resistance for use in turbocharger valve bushings (Courtesy JPMA)

Fig. 6 This ferrous bearing material has high permeability and oil content (Courtesy JPMA) Ferrous sintered bearing material with high permeability and oil content Hitachi Chemical Co. Ltd. received an award for the development of a ferrous bearing material that has highly permeability and oil content and that has already been used in printer head driving motors (Fig. 6). It is suitable for applications, which are difficult for oil impregnated sintered bearings to generate an oil film effect through a pumping action.

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Powder Metallurgy Review

JPMA Awards 2015

bearing material, which can be used in difficult conditions for achieving an oil film effect, was developed and was successfully adopted in printer head driving motors.

Development prize: Process

Fig. 7 Die wall lubrication in compaction makes it possible to achieve high density without additional manufacturing processes (Courtesy JPMA)

Fig. 8 Sinter-bonded planetary carrier, in which individual columns are joined to the main body of the carrier (Courtesy JPMA) Because of both a short operating time and a reversible rotation, the printer head driving motor is one of the most difficult applications, in which to obtain an oil film effect. Copper materials, which have high self-lubricity, were thought to be superior for such applications, but the development of a ferrous material was pursued in order to offer a less expensive bearing for the application. Increasing the oil supply ability of a bearing material is important in achieving an oil film effect under the usage conditions referred to above. Therefore, increasing permeability and oil content were deemed

Powder Metallurgy Review

to be the solution and these can be achieved by lowering density. However, lower density has a deleterious influence on productivity through poor green strength. Additionally, a material was required that had similar self-lubricity to a copper material for product reliability. The developed material achieved five times higher permeability than a conventional ferrous material, which has 80% density ratio. The green strength was maintained at a level equal to that of the conventional material by using both sponge iron powder and a new compaction lubricant. As a result, a ferrous

Winter 2015

Development of a high-density sprocket for automobile engines made by die wall lubrication and compaction at room temperature Hitachi Chemicals Co. Ltd, received a prize for this development, which relates to die wall lubrication in compaction and which makes it possible to achieve high density without additional manufacturing processes (Fig. 7). The developed technology realised products with densities of 7.5Â Mg/m3 and higher shape complexity, whilst eliminating the compacting speed rate-determining step in the lubricant coating process. In lubricant coating using the conventional spray method, reduction of compacting speed and the ability to respond to the incorporation of lightening holes were challenges. To solve these problems, a new die wall lubrication compacting method was developed, in which coating of the lubricant is completed in the die operation cycle from ejection from the compacting process to return for filling, thereby achieving the same compacting speed as in conventional compacting. In addition, in the spray method, the die is generally heated for the purposes of increasing the adhesion between the die wall surface and a solid lubricant, or drying the solution of a solid-liquid mixed lubricant. The developed method makes it possible to obtain the desired product properties under a cold condition (room temperature) without heating the die. Lubricating oil, which is supplied through the interior of the die, is coated uniformly on the die inner wall surface or side surface during die operation from the ejection position to return for filling. The coated lubricating oil functions as a release agent when the green compact is ejected after compacting and enables

ÂŠ 2015 Inovar Communications Ltd

JPMA Awards 2015

production of compacts with no galling. Furthermore, because dead space in the lubricant coating region, non-uniform lubricant coating due to concentration of the electrical field at convex shapes and other problems associated with the spray method do not occur, the developed method can respond easily to lightening holes and complex shapes. As a result of this development, industrial production of high density sprockets with higher productivity in comparison with the tooth flank form rolling method and the conventional warm die wall lubrication compacting method was successfully demonstrated.

Effort prize Development of planetary carrier for E-4WD applied with sinter brazing technology Sumitomo Electric Industries Ltd, received a prize for the development of a sinter-bonded planetary carrier, in which individual columns are joined to the main body of the carrier to overcome strength limitations (Fig. 8). A great focus has been placed recently on miniaturisation and weight savings in order to improve fuel efficiency, but the consequent adverse effect on components is that they are subjected to higher stress. The developed product is used in a planetary gear mechanism and this was designed to possess a large reduction ratio especially in large planetary gears in order to meet a requirement of weight saving and also to transfer rotation from motor to rear wheel. Therefore, stress reduction is one of the key factors in the planetary carrier design. In a conventional sinter-bonded carrier, the design of R feature is at the base of the column forming hollow shapes but only on one side, thus restricting its use to low torque units. Therefore, the company’s novel proposal was to incorporate the R feature design on both sides of columns thus relieving the high stress from the two sides of the

Fig. 9 This partially alloyed bronze powder with high compactibility achieves a homogenized sintered structure (Courtesy JPMA) columns. This has enabled the design of a carrier that can withstand high torque generated during high speed driving with sinter-bonding of the columns despite the weight saving features such as miniaturisation. This development has led to implementation of a sinter-bonded carrier in a high torque application which was conventionally difficult to achieve. The product has been adopted in a 4WD system used in hybrid vehicles. Partially alloyed bronze powder with high compactibility suitable for high sintered density Fukuda Metal Foil & Powder Co. Ltd received a prize for the development of a partially alloyed bronze powder with high compactibility to enable the prevention of demixing and segregation and achieve a homogenized sintered structure (Fig. 9). Either a mixture of copper and tin powders blended at the prescribed ratio, or alloyed powders produced by the atomisation method, have been generally used as a raw material for bronze sintered parts. However, the mixed powders cause demixing and segregation while they are flowing and a decrease in density of sintered compacts also occurs

because a large amount of liquid phase tin appears during sintering. Also, the gas inside sintering compacts has difficulty in escaping smoothly, especially in the case of the compacts with higher densities. On the other hand, alloyed powders do not cause demixing and segregation and achieve homogenized high density sintered compacts because the liquid phase does not appear in the sintering process. However, their compactibility is so poor that it is difficult to produce complex shaped parts using them. In order to solve these problems, electrolytic copper powder has been used as a matrix to improve the compactibility and bronze alloy powder with a high melting point has also been used as a tin source to avoid the formation of a liquid phase. These powders are diffusion-bonded to each other in order to suppress demixing and segregation. During the diffusion bonding, a heat treatment is carried out at a relatively low temperature to suppress inter-diffusion as much as possible. The target properties have thus been achieved and the powder has been successfully commercialised. www.jpma.gr.jp

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Let’s gear up together A robust helical PM gear compaction solution with 17% gear weight reduction in comparison to the wrought steel gear. This is one of our latest achievements at the Höganäs PoP Centre. Here, we are combining our latest metal powders and lubricant innovations with state-of-the-art multilevel press and helical gear tooling capability. We have used a novel design-for-PM approach to develop, prototype and test drive all gears in a design optimized popular European 6-speed passenger car transmission. The result: smart PM gear designs can help OEMs reduce weight and inertia in their transmissions. Additional advantages include cost saving opportunities through a shortened gear manufacturing process chain and lowered investment costs when setting up a new gearbox plant.

Join Höganäs and the Powder Metal Gearbox Initiative at CTI Symposium and Transmission Expo December 8-10 in Berlin, Germany Stand K 01

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Inspire industry to make more with less. www.hoganas.com/pmc