Degradation of yttria stabilized zirconia at 370 K under a low applied stress

The tetragonal-to-monoclinic phase transformation in ZrO2–3mol.%Y2O3 containing 0–5% A12O3 during aging in hot water (370 K) under 100 MPa stress is investigated. It is found that while a small tensile stress accelerates the degradation, a compressive stress has little affect on the degradation. The degradation of PSZ under tensile stress is considered to be caused by the reaction between Y2O3 and H2O. Small amount of A12O3 addition does not change the degradation mechanism of PSZ, but it prevents further continuation of degradation when the transformed volume reaches a certain value.