Quality performer

Advanced ceramics have worn the ‘engineering materials of the future’ mantle for some time, but there is a growing sense that their hour is finally arriving.

Their performance in demanding environments such as high temperatures and high-friction makes ceramics attractive for a wide range of applications, whether in general engineering or for specific needs in emerging areas such as biomaterials.

Research is also increasing into the production technology needed for their wider manufacturing applications.

PowderMatrix — one of the Faraday Partnerships set up by the government to stimulate growth in promising technology markets — listed an array of opportunities for ceramics in its ‘roadmap’ for the UK sector.

These included body armour, components for fuel cells, hightemperature materials for turbines, sensors, actuators and ceramic membranes. Ceramics technology also opens the way for a new generation of cutting tools.

Two examples of applied technologies from Morgan Technical Ceramics (MTC), a division of UK advanced materials giant Morgan Crucible, offer a flavour of the potential of advanced ceramics.

The first exploits the excellent properties of ceramics as a dielectric (non-conductive) material in mobile communications systems. MTC custom-designed a ceramic for Sarantel, the UK firm developing miniature high-performance antennas, pictured above. Sarantel’s technology, PowerHelix, comprises copper tracks deposited on to a small ceramic cylinder, laser-trimmed for optimum frequency response.

According to its developers, the combination of the highdielectric ceramic and PowerHelix’s twisted loop design gives the tiny antenna big performance benefits. The near-field of the antenna is tightly constrained, keeping radiation away from the user and helping to avoid the signal loss that afflicts many conventional antennas.

The second innovation involving MTC is, according to its developers, the first application of a piezoceramic material to an automotive fuel sensor.

The ceramics specialist worked with TI Automotive on a new fuel tank system for the 2005 Ford GT. The piezoceramic sensor replaces the float gauges more commonly used for monitoring fuel levels, which operate erratically when subjected to high levels of movement in the tanks of high- performance cars.

Located at the bottom of the tank, an electric current is sent to the piezoceramic material which oscillates in response. The resulting sound wave enters the liquid in the tank and returns to the transducer, giving an accurate measurement of the fuel level.

Smaller UK companies operating at the leading edge of ceramics technology include Surface Transforms, which is developing applications for carbon fibre-reinforced ceramic (CFRC) materials in aircraft and automotive braking systems.

Brakes are a good example of an area where the properties of ceramic materials come into their own. They must operate effectively across a wide range of temperatures and are subject to extreme friction.

Surface Transforms has signed deals with key players in both the automotive and aerospace sectors to develop commercial products.

While these promising applications bode well for the UK ceramics sector, PowderMatrix identified the need for further work on manufacturing capabilities in the sector. The area of costeffective rapid prototyping and tooling is a good example.

Dr John Fernie, technology manager for ceramics at materials research specialist TWI, said the UK’s track record in the sector had fluctuated over the past 20 years, but now showed promising signs of getting back up to full speed.

‘In certain areas we are worldleading, and our university research base is very good indeed,’ said Fernie. ‘Our industrial research base is less strong. Many companies had an active ceramics research element in the mid 1980s but they lost their way a little in the 90s when the difficulties became apparent.’

Fernie said the impetus that built up as ceramics were hailed as ‘world-dominating materials’ stalled as companies realised significant challenges remained.

‘They saw a load of problems, none of them insoluble, and realised they’d have to put in the research effort. Many companies shied away from that.’

Fernie believes that lost impetus is returning as industrial companies realise that, however hard they look, there are some applications for which ceramics are the only long-term option. This has sparked renewed interest in the enabling technologies that will widen their application base.

TWI, for example, has developed a range of expertise in joining engineering ceramics to other materials.

‘Ideally you only want to have to use ceramics when they are really needed, which means you need a good joining technology.’