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.