Composite challenge

High cost and temperature limitations need to be resolved for a new alloy

By Sue Stuckey

Pressure diecaster Kaye Presteigne has a problem.

Working with materials supplier London & Scandinavian Metallurgical Company and researchers at Nottingham University, it has come up with an aluminium alloy composite reinforced with particles of titanium diboride that is three times better at resisting wear than the base LM24 alloy. But it costs four times and much and, with a top operating temperature of around 500 degreesC, no-one has worked out what it could be used for.

But for its temperature limitation, the material might have been an obvious choice for automotive brake applications. Typically it could be used where a component rubs against a steel surface.

The main benefit is that the material can be diecast into a very dense structure with remarkably low porosity of well under 1%. But Frank Bell, KP’s R&D manager, explains that up to 5% porosity could be acceptable depending on component design.

Lowering the porosity makes the material harder and tougher and allows castings to be produced to tigher tolerances which cuts down on finish machining costs. The new composite is around 10% stiffer, too.

The challenge for KP is to get the cost down to around that of the base material.

The company, which makes castings in sizes that range from `a Cadbury’s creme egg up to that of a small computer printer’, says using the material will give it much greater confidence in the integrity of its castings.