EFFECTS OF GRAIN-SIZE AND CERIA ADDITION AN AGING BEHAVIOR AND TRIBOLOGICAL PROPERTIES OF Y-TZP CERAMICS

The influence was investigated of ceria addition and the grain size on ageing and wear behaviour of Y-TZP ceramics. Two types of ceramics we re studied: ZY5 (95mole% ZrO2 and 5 mole% YO1.5) and ZY4Ce4 (92mole% Z rO2, 4mole% YO1.5) and 4mole% CeO2). Each ceramic was sintered with gr ain sizes of 0.18 mu m (95% dense) or 0.5 mu m (98% dense). Only the Z Y5 ceramic with a grain size of 0.5 mu m showed degradation to monocli nic zirconia (= ageing) after a treatment in water at 180 degrees C. T his ceramic was also the only one in which a phase transformation was observed after wear tests in water for a pin (SiC) on plate test confi guration. However, this transformation was found not to affect the wea r rate. Wear mechanisms were investigated for testing in dry nitrogen and water environment. (C) 1998 Elsevier Science Limited. All rights r eserved.