Effect of Co-doping of Al<sub>2</sub>O<sub>3</sub> and La<sub>2</sub>O<sub>3</sub> on Hygrothermal Aging Resistance and Mechanical Propert

3YSZ ceramics exhibit inadequate poor resistance to hygrothermal aging when used in dental applications. To enhance the hygrothermal aging resistance of 3YSZ ceramics while maintaining their mechanical properties, 3YSZ was microdoped by Al₂O₃ and La₂O₃ in different ratios, and then sintered at 1450 ℃ for 3 h to achieve densification. The microscopic morphology of the samples was observed using field emission scanning electron microscopy. The hardness, toughness and relative density of different samples were tested. The samples were subjected to hygrothermal aging tests with varying durations, and the resistance of the samples to hygrothermal aging was evaluated in terms of the content of monoclinic phase and aging kinetic parameters in the aged samples. The results show that with the increase of the doping amount, the resistance of the samples to hygrothermal aging increases and the fracture toughness gradually decreases, in which the 3Y-0.15Al-0.2La ceramic contains 24% (volume fraction) of cubic phase with Vickers hardness of (13.09±0.41) GPa and fracture toughness of (9.03±0.3) MPa·m^1/2. After 200 h of hygrothermal aging, the saturation content of monoclinic phase on the surface remains at 24% (volume fraction), indicating excellent mechanical properties and hygrothermal aging resistance, making it a promising canidate as a ceramic restorative material in indentistry.