LOW-TEMPERATURE AGING OF ZIRCONIA-TOUGHENED ALUMINA UNDER HUMID CONDITIONS

Changes in crystalline phases resulting from low-temperature annealing of different yttria (3 mol%) and ceria (14 mol%) doped PSZ and TTA co mpositions were investigated under controlled humidity conditions betw een 150 and 250 degrees C up to 24 h. It was observed that 70% of the tetragonal phase in 3Y-PSZ had transformed to monoclinic phase while t his effect decreased as alumina was added to the system. However, the composition with Al2O3 + 15 vol% 3Y-PSZ, which had the best mechanical properties, showed appreciable dependence on hydrothermal treatment. On the contrary, Ce-doped PSZ did not show any aging degradation.