Phase transformation of zirconia ceramics by annealing in hot water

Abstract

The tetragonal-to-monoclinic phase transformation of Y2O3-doped tetragonal ZrO2 polycrystals (Y-TZP) was investigated by annealing at 140°C in hot water. Sintered bodies of Y-TZP were prepared by sintering at temperatures ranging between 1300 and 1500°C, using a 3 mol% Y-TZP fine powder, synthesized by means of the hydrolysis method, as a starting powder. X-ray diffraction measurements on the sample surfaces and Rietveld analyses revealed that the amount of cubic phase increased and the Y2O3 concentration within the tetragonal phase decreased as the sintering temperature increased. Scanning electron microscopy measurements also showed that the grain size on the sample surfaces increased as the sintering temperature increased. When the sintered bodies were subjected to annealing in hot water, the phase-transformation rate on their surfaces increased as the sintering temperature increased. This behavior can be explained by both the decrease in the Y2O3 concentration within the tetragonal phase and the increase in the grain size.