CONTROL OF THE TETRAGONAL TO MONOCLINIC PHASE TRANSFORMATION OF YTTRIA-DOPED ZIRCONIA CONTAINING CeO//2, CaO AND Al//2O//3 IN AIR AND WATER.

Yttria doped tetragonal zirconia polycrystals containing CeO//2, CaO and Al//2O//3 were sintered at 1400-1600 degree C for 3 hr, and the mechanical properties and thermal stability of the sintered bodies were evaluated. The degree of the tetragonal-to-monoclinic phase transformation by annealing increased with increasing water vapor pressure by Langmuir type relation and decreased with decreasing the grain size of ZrO//2 and increasing both CeO//2 and Al//2O//3 contents. Dispersion of Al//2O//3 improved the fracture toughness and elasticity of the composites and alloying less than 8 mol% of CeO//2 caused no significant change in the mechanical properties.