氧化锆增韧陶瓷的室温动态疲劳

DYNAMIC FATIGUE BEHAVIOR OF ZIRCONIA TOUGHENED CERAMICS AT ROOM TEMPERATURE

用动态疲劳试验法研究了３Ｙ－ＴＺＰ和３Ｙ－ＴＺＰ／Ａｌ_２Ｏ_３（２０ｗｔ％）陶瓷在空气中的室温动态疲劳，并讨论了疲劳慢裂纹扩展特性。另外利用动态疲劳数据对两种陶瓷的平均寿命进行了预测。两种陶瓷材料在室温下均存在着慢裂纹扩展，主要是由空气中水蒸汽的应力腐蚀所造成的，且裂纹是沿晶界玻璃相扩展的。相变诱发的表面压应力和裂纹尖端的正应变可提高疲劳抗力。在８００ＭＰａ应力作用下，３Ｙ－ＴＺＰ和３Ｙ－ＴＺＰ／Ａｌ_２Ｏ_３（２０ｗｔ％）的平均寿命分别为２４ｍｉｎ和７２ｈ，平均寿命随应力的增大而缩短．

Dynamic fatigue tests of 3Y-TZP and 3Y-TZP/Al_2O_3(20wt%)ceramics were carried out in air at room temperature,and the slow crack growth behavior was also discussed,Besides,the aver age lifetime of these two ceramics were predicted from dynamic fatigue data. The slow crack growth at room temperature is observed in both ceramics,which may result from the stress corrosion by humidity in air and the cracks propagation through the glass phase nearby the grain boundaries,The fatigue resis tance could be increased by the surface compressive stress induced from phase transformation and the positive strain at crack tip.The average lifetimes of 3Y-TZP and 3Y-TZP/Al_2O_3(20wt%)ceramics are about 24 minutes and 72 hours,respecitively,at the applied stress of 800MPa,and the average lifetime decreaseds with increasing the applied stress.