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Ceramic research reaches new heights

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05.03.2002

Materials scientists at the University of Wales Aberystwyth (UWA) are taking ceramics to new heights in order to determine the structure and stability of the materials which are used to construct aeroplane engines and the tiles for the space shuttle.

Dr Rudi Winter and colleagues from the Department of Physics at UWA are using a unique combination of techniques to study the materials at extreme temperatures which simulate those experienced when aircraft travel at high speed or when they decelerate rapidly.

"Ceramics have been used as heat shields in spacecraft re-entering into the atmosphere, and in aircraft engines because the burning temperatures are too high for most metals." says Dr Winter. "At present, ceramic linings are not used for normal civil aircraft, although metal-ceramic composites may be used one day for that purpose if the favourable mechanical properties of metals can be married with the good thermal behaviour of ceramics. That is why it is important to understand the structural response of these materials to mechanical and thermal impact, so that we learn to square the circle.".

Dr Winter and CASE Student Malcolm Coleman are therefore applying Nuclear Magnetic Resonance (NMR) together with a new non-contact thermometry technique for the very first time in order to study the stability and structure of these ceramics under real conditions, i.e. at very high temperatures up to 2200oC.

The aim of the project is to implement a novel technique for contactless temperature measurement (laser-absorption radiation thermometry - LART), on the ultra-high temperature aerodynamic levitation-based NMR probe - the only one of its kind in the UK - to determine the atomic structure of these ceramics.

"NMR allows us to determine the structure of a material (at an atomic level) around probe atoms in a material in a similar manner to which its close relative, MRI - magnetic resonance imaging - exploits the same physics to probe human "samples" in medicine." continues Dr Winter.

"The probe is able to heat the samples without needing a container to temperatures up to 2200oC by means of a 125W infrared laser. In order to determine the structural changes, the temperature will be measured and controlled with previously unreached precision using the LART technique which has been developed by our colleagues at the National Physical Laboratory (NPL)".

For Dr Andrew Levick in the Thermal Metrology Group at NPL, this work is a showcase for their new laser-absorption radiation thermometry (LART) technique which overcomes many of the problems inherent in conventional pyrometry techniques. They hope that Dr Winter will be able to demonstrate its feasibility in practical applications in order for them to be able to market it to the industry in the near future.

The three-year project has been made possible by a grant of £40,000 from the Engineering and Physical Sciences Research Council (EPSRC) and support from National Physical Laboratory.

Arthur Dafis | Source: alphagalileo

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