Stability under Hydrothermal Conditions and Fracture Strength of Yttria- and Ceria-Doped Tetragonal Zirconia/Alumina Composites Fabricated by HIPping

Yttria- and ceria-doped tetragonal zirconia ((Y, Ce)-TZP) /Al2O3 composites were fabricated by HIPping at 1400° to 1600°C and 147MPa for 0.5h in Ar, and their bending strength, microstructure and stability under hydrothermal conditions at 180°C and 1MPa were studied. The bending strength of (4Y, 4Ce)-TZP/25wt% Al2O3 composites HIPped at 1400°C was 1600MPa. The thermal stability of (Y, Ce)-TZP/Al2O3 composites increased with decreasing HIP temperature, since it depends on the HIP temperature. (4Y, 4Ce)-TZP/25wt% Al2O3 composites HIPped at 1400°C showed improved stability under hydrothermal conditions at 180°C and 1MPa. The composites treated at 1600°C showed marked grain growth as compared with 3Y-TZP/Al2O3 composites, and their bending strength was greatly reduced to less than that of normal sintered bodies. HIPping below 1500°C in Ar was useful to densify the composites and to improve the fracture strength.