Custom Metal Powder Production Using Ultrasonic Atomisation

By Dr. Cameron Chai and Peter Airey

Processes such as metal additive manufacturing and thermal spraying rely on free flowing, spherical metal powder feedstocks. If your requirement only calls for standard alloys and off-the-shelf particle sizes, you are probably well catered for. But, if you need something else, like a specialty alloy, or your process doesn’t suit the standard product sizes, you might get a shock when you get a quotation for the metal powder you are after. Fortunately, the Amazemet rePowder ultrasonic atomisation system allows you to produce custom alloys and tailor your particle size to your own specific needs.

Traditional Powder Production

Most metal powders are produced by a process called gas atomisation. It involves hitting a stream of homogenised molten metal with a jet of high-pressure inert gas and is suited to large production runs of the order of 50kg or more. Changing composition and modifying the process is an expensive undertaking, which will no doubt be passed on to you.

The Alternative – Ultrasonic Atomisation

In 2016, Łukasz Żrodowski, a Ph.D. student looking for a small quantity of powder rediscovered ultrasonic atomisation that had been dormant for 40 years. The process involves pouring a stream of molten metal onto a vibrating plate or sonotrode. The rapidly vibrating sonotrode ejects droplets of molten metal that solidify in an inert atmosphere. The particle size is controlled by vibration frequency and amplitude.

Over the coming years Łukasz refined the process and founded Amazemet in 2019. He commercialised ultrasonic atomisation technology in the form of the rePowder. With a modular architecture it can be tailored with an induction furnace (for alloys melting up to 1300°C) or arc/plasma furnace (for alloys melting up to 3500°C) and other feed systems. There are now more than 30 installations around the world including several in the USA and China.

Advantages of Ultrasonic Atomisation

The Amazemet rePowder is ideal for small production runs in batches which makes it ideal for alloy prototyping and powder optimisation. Ultrasonic atomisation has many benefits including:

• Compact Size – Enables systems to be easily located in labs close to AM equipment

• Suitable for any alloy composition –Suits everything from pure elements to exotic/refractory alloys

• Any form or feedstock – Caters for any source materialfrom chips, failed AM prints, damaged samples, rods, wire, powder, etc.

• Controllable particle size – Alloy particle size is a function of sonotrode vibration frequency and amplitude

• Low running costs – Relatively low gas consumption

• Variable capacity – Process batches from just a few grams to multiple kg per day

• Recycling – Use printed or failed parts or scrap material from DMLS, SLM and other processes as feedstock

• Modularity – Add new modules to expand the system’s capabilities

• Versatility - Prepare new compositions, alloy homogenisation, ultrasonic atomisation, suction casting and further options in development

• Multiple alloys in one day – rePowder can be easily cleaned and configured to run multiple different alloys in a single day

Powder Properties

Ultrasonic atomisation produces powders with unrivalled sphericity (>0.98) with a very tight particle size distributions, ensuring more consistent processing properties for both AM and thermal spray processes

Summary

Ultrasonic atomisation systems like the Amazemet rePowder are ideal for researchers and commercial entities looking to produce custom alloy powders with optimised composition and/or particle size in small batches from virtually any feedstock. Due to their small size and affordability, they can be located in almost any lab. The resultant metal powders have excellent sphericity and tight particle size distributions making them ideal for additive manufacturing and thermal spray processing.

For more details, please contact info@axt.com.au