Thermal expansion of β-eucryptite in oxide-based ceramic composites

This paper presents an experimental investigation on the thermal expansion behaviour of beta-eucryptite (E) when it is used for processing alumina/beta-eucryptite (AE) or zirconia/beta-eucryptite (ZE) composites. Composite materials were prepared from a beta-eucryptite powder synthetised in our laboratory and commercially available alumina or zirconia nanopowders. In order to preserve the beta-eucryptite crystalline phase in sintered materials, the pressureless sintered step was performed at relatively low temperatures (<1300 degrees C). It is experimentally shown that in well-densified oxide-based composites, the beta-eucryptite lost its slightly negative thermal expansion coefficient. This behaviour could be related to compressive residual stresses applied on beta-eucryptite grains due to the thermal expansion mismatch between alumina or zirconia and the beta-eucryptite. (C) 2012 Elsevier Ltd. All rights reserved.