Nondestructive reliability monitoring of zirconia degraded under hydrothermal condition

3%yttria-stabilized tetragonal zirconia polycrystal (3mol% Y₂O₃-ZrO₂, 3Y-TZP) ceramic suffers from low temperature degradation (LTD) during long time use under hydrothermal condition. In this research, an attempt was made for monitoring hydrothermal degradation of the ceramic by using semi-nondestructive X-ray diffraction (XRD) method. In order to simulate accelerated hydrothermal degradation, the specimen was placed under water vapor atmosphere at 134° C 150°C and 200°C in an autoclave for various exposure time up to 40 hours. From the X-ray diffraction peak, two feature parameters including intensity ratio and full width at half maximum were determined and observed to increase with hydrothermal exposure time and temperature. The consistent changes in XRD parameters were correlated with the tetragonal-to-monoclinic microstructural change. Based on the established linear correlations with hardness reduction, potentials of the two XRD parameters were suggested for health-monitoring of the hydrothermally exposed 3Y-TZP ceramic.