Densification and Deformation of Partially Sintered Zirconia-Preform under Uniaxial Compressive Stress

The uniazial compression was applied with a hot press apparatus for the partially sintered preforms with three chemical compositions, 3mol% Y2O3-ZrO2 (TZ-3 Y), 6mol% Y2O3-ZrO2 (TZ-6 Y), and 8mol% Y2O3-ZrO2 (TZ-8 Y). The change in size was measured after pressing. Obviously, the densification occurred below 1350°C and superplastic defomation appeared mainly over 1350°C. The grain size at 1500°C was 2μm in TZ-8 Y in comparison with 0.4μm in TZ-3 Y. TZ-6 Y and TZ-8 Y had a porosity of 5-15% because of the rapid grain growth. Consequently, small bending strengths in the range of 20-30kgf/mm2 were obtained. In TZ-3 Y, the compressive deformation gave a rapid increase in strength up to 140kgf/mm2. But the strength decreased above 1450°C, due to the formation of R-phase, by Kitano et al. (1987).