Fracture toughness, strength and Vickers hardness of yttria-ceria-doped tetragonal zirconia/alumina composites fabricated by hot isostatic pressing

Abstract

Yttria-ceria-doped tetragonal zirconia ((Y, Ce)-TZP)/alumina (Al2O3) composites were fabricated by hot isostatic pressing (HIP) at 1400–1600 °C and 147 MPa for 30 min in Ar gas using fine powders prepared by hydrolysis of ZrOCl2 solution. The mechanical properties of these ceramic composites were evaluated. The fracture toughness and bending strength of the composites consisting of 25 wt% Al2O3 and tetragonal zirconia with compositions 4 mol% YO1.5-4 mol% CeO2-ZrO2, 2.5 mol% YO1.5-4 mol% CeO2-ZrO2 and 2.5 mol% YO1.5-5.5 mol% CeO2-ZrO2 fabricated by HIP at 1400 °C were 6–7 MPa m1/2 and 1700–1800 MPa. Fracture toughness, strength and hardness of (Y, Ce)-TZP/Al2O3 composites were strongly dependent on HIP temperature. The fracture strength and hardness were increased, and grain growth of zirconia grains and phase transformation from the tetragonal to the monoclinic structure of (Y, Ce)-TZP during HIP in Ar at high temperature (1600 °C) were suppressed by the dispersion of Al2O3 into (Y, Ce)-TZP.