Microstructural characterization of Ce-TZP/Al2O3 after degradation in water

In this study, the long-term resistance of Ce-TZP/Al2O3 specimens to hydrothermal treatment is evaluated in terms of their microstructure. Treatment of the specimens is carried out in an autoclave with water at 134(degrees)C for up to 360 h. The biaxial strength and Weibull modulus of the specimens remains unchanged after 120 h of hydrothermal treatment, and their pseudo-plasticity is preserved. However, after 360 h of hydrothermal treatment the biaxial strength decreases by 12% and the Weibull modulus is also decreased. The transformation surface layer is observed through scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The thickness of the transformation layer can be estimated only through TEM analysis, revealing minimal microcrack formation at the surface layer. For comparison, several Y-TZP specimens are also prepared. After 24 h of hydrothermal treatment, the monoclinic phase content in the Y-TZP specimen reached 60%, resulting in a 40% decrease in strength. This strength decrease can be attributed to microcrack formation in the surface layer.