ぜい性材料の固体微粒子によるエロージョン (第10報)

正方晶ZrO₂セラミックスのエロージョンによる強化

抄録

Strengthening tetragonal ZrO₂ ceramics by the erosion caused by iron spheres and SiC abrasives has been studied. When tetragonal ZrO₂ ceramics, TOSO: TZ-3Y, was eroded by SiC abrasives with an average particle size of 0.5mm, at 100m/s and 45deg, a surface layer about 15-20μm thick with compressive stress was formed and the bending strength increased from 850MPa to 1130MPa on the average. The surface layer acquired a large apparent K_IC. Reversion of the (002)/(200) peak height ratio, induction of a 1200MPa compressive stress in tetragonal ZrO₂, and broadening in all diffraction peaks were observed in the surface layer in X-ray diffraction analysis. Small amounts of monoclinic and rhombohedral ZrO₂ transformed from tetragonal ZrO₂ were also detected. After heat treatment at 1200°C for 2h, monoclinic and rhombohedral ZrO₂ disappeared. The crystallinity of tetragonal ZrO₂ was improved and the compressive stress became zero, but the (002)/(200) peak height ratio kept the reversion. Heat treatment decreased the bending strength of eroded specimens to 580MPa.