部分安定化ジルコニアの疲労特性に及ぼすアニールの影響

抄録

The material often would be subjected to cyclic load in corrosive circumstance as living body. The better fatigue strength is rather needed in such condition. In our previous paper, it was found that there was an appreciable degradation in fatigue life time of yttria doped tetragonal zirconia polycrystals (TZP). In this study, the materials were annealed for 100 h at the respective temperatures of 200, 400 and 600°C in a low vacuum atmosphere to improve the decrease in the fatigue life. On using those annealed specimens both static and cyclic fatigue tests were conducted under static four-point bending and under cyclic reversed plane bending respectively. The obtained test results indicated that there was an appreciable increase in lifetime in the case of cyclic fatigue by low applied load for the specimens annealed at the low temperatures of 200 and 400°C. These results shows that the occurrences of fine microcracenlargement of process zone in wake field of crack on cycling loading which contribute to the ks accompanied with phase transformation phase cause the increase of crack propagation resistance.