EFFECT OF ADDITIVES ON DENSIFICATION AND DEFORMATION OF TETRAGONAL ZIRCONIA

The effect of additives (Bi2O3, Fe2O3) on densification and creep rate s of tetragonal ZrO2-Y2O3 has been investigated. In Bi2O3-doped Y-TZP, a reactive liquid forms at temperatures above 800-900 degrees C, whic h leads to a strong enhancement of densification for concentrations of 1-2 mol% Bi2O3. However, during cooling from the processing temperatu re a strong, undesirable transformation of the tetragonal to the monoc linic phase occurs. The addition of 0.6-1.2 mol% FeO3/2 promotes densi fication without destabilizing the tetragonal phase. A concentration o f 1.2 mol%, however, induces discontinuous grain growth, while this is not the case for 0.6 mol%. Creep rates of Y-TZP were enhanced by a fa ctor of 4-6 by adding 0.6 mol% FeO3/2.