Y-TZPの低温熱処理による熱劣化深さ

抄録

The mechanical properties of yttria-doped tetragonal zirconia polycrystals (Y-TZP) are known to be degraded by aging at 100∼300°C in air due to tetragonal to monoclinic phase transformation. In the present study, hot-water aging tests were done for several Y-TZP specimens having different grain size which were made from raw powders with different specific surface area. The tetragonal to monoclinic phase transformation zone depth from the surface after the hot-water aging was measured by a thin film X-ray diffraction method, by which the small amount of transformed monoclinic phase existing very close to the surface can be detected.
Y-TZP with the small grain size of 0.15μm, made by firing at 1300°C for 3 hours using zirconia raw powder with specific surface area of 30m²/g, showed only a small amount of transformed monoclinic phase even by 200°C hot-water aging for 100 hours. Furthermore, its phase transformation depth was only 2.3μm and the depth did not increase even after a more prolonged aging time.