抄録
The influences of ZrO2 particle addition upon improvement in mechanical properties of Al2O3 ceramics and their degradation due to a deionized water environment under high temperature and high pressure were investigated in terms of the microstructural changes and residual strength characteristics. Sintered Al2O3 bodies containing, 3.3, 10.2, 21.7vol.% of 3mol% Y2O3-doped tetragonal ZrO2 were made using a pressureless sintering process at 1550, 1600, 1650°C, respectively. These ceramic composites were corroded in deionized water under its equilibrium vapor pressure of 1.59MPa at 200°C. The effects of microstructure upon mechanical properties of Al2O3/ZrO2 composites were studied for the specimens treated with, and not treated with water under high temperature and pressure, by residual bending strength measurement, FE-SEM with EDX spectrometry observation and XRD and FE-TEM structural analysis. The mechanical properties were found to be superior when specimens were 21.7vol.% of ZrO2 contents and sintered at 1550°C. It was shown that the strength degradation due to the corrosion by deionized water molecule was suppressed in the case of the specimens with higher contents of ZrO2 particles sintered at lower temperatures. The correlation between bending strength scatter and microstructural defects was discussed.
