Transformation of Yttria‐Doped Tetragonal ZrO ₂ Polycrystals by Annealing in Water

Abstract

Phase changes and the microstructure resulting from low‐temperature annealing of yttria‐doped tetragonal ZrO 2 polycrystals in water were investigated at 65° to 120°C. Tetragonal ZrO 2 on the surface of the sintered body transformed to the monoclinic phase, accompanied by microcracking. The transformation rate in water, which was much greater than that in air, was first order with respect to surface concentration of tetragonal ZrO 2 . Nonaqueous solvents with a molecular structure containing a lone‐pair electron orbital opposite a proton donor site also greatly enhanced the transformation.