Enhancing the hydrothermal aging resistance of alumina-toughened zirconia <i>via</i> cerium oxide doping

This study investigates the influence of cerium oxide (CeO₂) doping on the densification, microstructure, mechanical properties, and hydrothermal aging resistance of alumina-toughened zirconia (ATZ) ceramics. ATZ composites with 0-1 wt% CeO₂ were synthesized and sintered at 1250-1500 °C. Results showed that CeO₂ doping significantly enhanced densification, with the highest relative density (∼92.1%) achieved at 0.2 wt% CeO₂ and 1500 °C. Microstructural analysis revealed refined, equiaxed grains without secondary phase formation, and EDX confirmed uniform Ce distribution within the zirconia matrix. Vickers hardness increased with both sintering temperature and Ce content, peaking at 12.18 GPa for 0.2 wt% CeO₂. Hydrothermal aging tests (180 °C, 10 bar, 100 h) demonstrated that CeO₂ effectively suppressed the tetragonal-to-monoclinic phase transformation, reducing monoclinic content from ∼31.7% in undoped ATZ to ∼9.6% in the 0.2 wt% sample. SEM analysis corroborated these trends, showing severe surface degradation in undoped samples and minimal damage in optimally doped ones. These findings establish 0.1-0.2 wt% CeO₂ as the optimal range for enhancing the long-term structural and mechanical stability of ATZ ceramics for biomedical applications.