Grain-Boundary Engineering for Aging and Slow-Crack-Growth Resistant Zirconia

Ceramic materials are prone to slow crack growth,resulting in strength degradation over time. although yttria-stabilized zirconia (y-tzp) ceramics have higher crack resistance than other dental ceramics,their aging susceptibility threatens their long-term performance in aqueous environments such as the oral cavity. unfortunately,increasing the aging resistance of y-tzp ceramics normally reduces their crack resistance. our recently conducted systematic study of doping 3y-tzp with various trivalent cations revealed that lanthanum oxide (la2o3) and aluminum oxide (al2o3) have the most potent effect to retard the aging kinetics of 3y-tzp. in this study,the crack-propagation behavior of la2o3 and al2o3 co-doped 3y-tzp ceramics was investigated by double-torsion methods. the grain boundaries were examined using scanning transmission electron microscopy and energy-dispersive spectroscopy (stem-eds). correlating these analytic data with hydrothermal aging studies using different doping systems,a strategy to strongly bind the segregated dopant cations with the oxygen vacancies at the zirconia-grain boundary was found to improve effectively the aging resistance of y-tzp ceramics without affecting the resistance to crack propagation. © international & american associations for dental research.