STRENGTH AND PHASE-STABILITY OF YTTRIA-CERIA-DOPED TETRAGONAL ZIRCONIA ALUMINA COMPOSITES SINTERED AND HOT ISOSTATICALLY PRESSED IN ARGON OXYGEN GAS ATMOSPHERE

Yttria-ceria-doped tetragonal zirconia ((Y,Ce)-TZP)/alumina (Al2O3) composites were fabricated by hot isostatic pressing at 1400-degrees to 1450-degrees-C and 196 MPa in an Ar-O2 atmosphere using the fine powders prepared by hydrolysis of ZrOCl2 solution. The composites consisting of 25 wt% Al2O3 and tetragonal zirconia with compositions 4 mol% YO1.5-4 mol% CeO2-ZrO2 and 2.5 mol% YO1.5-5.5 mol% CeO2-ZrO2 exhibited mean fracture strength as high as 2000 MPa and were resistant to phase transformation under saturated water vapor pressure at 180-degrees-C (1 MPa). Postsintering hot isostatic pressing of (4Y,4Ce)-TZP/Al2O3 and (2.5Y,5.5Ce)-TZP/Al2O3 composites was useful to enhance the phase stability under hydrothermal conditions and strength.