The role of light rare earths in the thermal degradation behavior of ZrO{sub}-CeO{sub}-Y{sub}2O{sub}3 ceramics

摘要

The objective of this paper is to evaluate the light rare earth influence on hydrothermal ageing behaviour of ZrO{sub}2 -CeO{sub}2 -Y{sub}2O{sub}3 ceramics at low temperatures ( 200 - 300 °C). With this purpose zirconia samples doped with 2 mol% of yttria and 10 mol% of light rare earth oxides were prepared using light rare earth concentrates. Powders were synthesized by the coprecipitation route. Apparent density values were determined by Archimedes method. The sintered pellets were characterized, before and after the ageing tests at 250 °C for 100 hours, by X - ray diffraction (Rietveld refinement), Vickers indentation technique, scanning electron microscopy and grain size determination. Results indicate that light rare earth presence has no significant effect on ZrO{sub}2 -CeO{sub}2 -Y{sub}2O{sub}3 ceramics performance. It was verified that the high purity oxides, that present high costs, are not required to obtain zirconia ceramics with better properties.