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Advances in technology across industry

Perfectly smooth cylinders

IN future, Mercedes-Benz engines will be even more fuel-efficient, more resistant to wear and markedly lighter. These improvements have been made possible by NANOSLIDE technology, which has been evolved and developed to production standard by MercedesBenz. NANOSLIDE produces a perfectly smooth cylinder barrel, resulting in extremely low piston friction far below previously attainable levels. Mercedes-Benz has received the MATERIALICA Award 2011 in recognition of this achievement.

The NANOSLIDE technology developed by Mercedes-Benz employs twin-wire arc-sprayed coating (TWAS) to optimise cylinder surfaces. After melting iron-carbon wires by means of an electric arc, a flow of gas is applied to spray the metal droplets onto the inner walls of the cylinders of the lightweight aluminium crankcase. Extremely fine finishing of the resultant ultra-fine to nano-crystalline iron layer produces an almost perfectly smooth surface with fine pores which reduces friction and wear between pistons and cylinder walls by up to 50 percent in comparison to the barrel technologies available to date and additionally possesses an extremely high level of wear resistance. The resultant benefits are reduced fuel consumption and emissions, plus a markedly lighter engine.

Nanotubes key to microscopic mechanics

IN the latest issue of Elsevier’s Materials Today, researchers from Spain and Belgium reported on the innovative use of carbon nanotubes to create mechanical components for use in a new generation of micro-machines. While the electronics industry has excelled in miniaturising components, reducing the size of mechanical systems has proved much more challenging.

One of the difficulties of shrinking mechanical devices is that the conventional techniques used to produce individual components are not useful when it comes to creating intricate shapes on the microscale. One technique is electrical discharge machining (EDM), which uses a spark of electricity to blast away the unwanted material to create complex shapes. However, this method requires that the target material is electrically conductive, limiting the use of EDM on hard, ceramic materials.

But now, by implanting carbon nanotubes in silicon nitride, Manuel Belmonte and colleagues have been able to increase the electrical conductivity of the material by 13 orders of magnitude and used EDM to produce a microgear without compromising the production time or integrity of the apparatus.

FESEM (a) and TEM (b) micrographs of the fracture surface of Si3N4/MWCNTs nanocomposite. The arrows in (b) point to the MWCNTs. Images courtesy of Manuel Belmonte.

New record voltage for organic solar cells

Molecar Solar Ltd, a spinout company from the University of Warwick, has achieved a significant breakthrough in the performance of solar photovoltaic (PV) cells. They have achieved and demonstrated a record voltage for organic photovoltaic cells that means these highly flexible, low cost solar cells can now be devolved for commercial uses in a wide range of consumer electronics.

The company’s most recent advance in the development of its organic photovoltaic (OPV) cell technology is the realisation of cells with opencircuit voltages in excess of 4 volts for the first time. Molecular Solar’s research team believe this is a record for an OPV device. Dr Ross Hatton, research director of the company commented: “This is an important advance. We are now very close to having highly flexible organic photovoltaic cells that will be capable of delivering electrical energy at a voltage suitable for recharging lithium ion batteries that are widely used in portable consumer electronics. Remarkably, this high voltage is achieved using a cell with only 4 junctions (sub-cells).”

University of Warwick researcher Professor Tim Jones, who is chief technology officer of Molecular Solar, added: “The first generation of organic photovoltaics will be exceptionally well matched to consumer electronics applications. The advantage of Molecular Solar’s high voltage cells is that a single cell can be used with no requirement to connect multiple cells in series for these applications, saving manufacturing cost.” Visit: www.ventures.warwick.ac.uk