可切削玻璃陶瓷疲劳断裂的微观机制  

Fatigue Fracture Micro-Mechanism of a Machinable Glass-Ceramic

作　　者：乔冠军[1] 高积强[1] 王永兰[1] 金志浩[1] 

机构地区：[1]西安交通大学材料科学与工程学院,西安710049

出　　处：《西安交通大学学报》2001年第7期736-740,共5页Journal of Xi'an Jiaotong University

基　　金：国家自然科学基金资助项目 (5 0 0 72 0 17) .

摘　　要：系统研究了在静载荷、动载荷及循环载荷的作用下 ,一种典型可切削玻璃陶瓷的疲劳断裂机理 .以显微组织分析及断口分析为手段 ,重点研究了氟金云母的“卡片框架”组织与疲劳裂纹的交互作用 ,以及循环载荷对材料造成的附加损伤 .实验结果表明 ,在静载荷作用下 ,初始P型裂纹首先稳态扩展 ,随后合并为半圆径向裂纹并最终失稳断裂 .裂纹扩展路径的选择性对应力速率十分敏感 ,随着应力速率的增加 ,裂纹沿云母片层间扩展而发生偏折的倾向逐渐减弱 .实验观测到了循环载荷诱发压痕中位裂纹形成的现象 .伴随中位裂纹产生的断裂棱 ,导致裂纹面的宏观不匹配 ,是循环载荷对材料造成附加损伤的重要原因 .The fatigue fracture mechanism of a typical machinable glass-ceramic under static, dynamic and cyclic loading was investigated. The effects of 'Card-Frame' microstructure of fluoromica crystals on fatigue crack propagation were investigated by microstructure and fractured surface analysis. Additional damage of material from cyclic loading was also discussed. Experimental results showed that, under static loading, the original indentation Palmqvist type cracks propagate stably at first, and then the two Palmqvist cracks combine into one half-penny radial crack which propagates unstably and leads to specimen fracture finally. The selectivity of crack propagation route is very sensitive to the applied stress-rate. The crack interlaminar extension and deflection tendency decreases with increasing stress-rate. A phenomenon of median crack arising under cyclic loading is observed. The macro dismatching in fractured surface caused by fractured-edge accompanied with median crack is one important source of additional damage on material under cyclic loading.

关 键 词：可切削玻璃陶瓷 疲劳断裂 显微组织分析 断口分析 

分 类 号：TQ174.758[化学工程—陶瓷工业] TQ174.1[化学工程—硅酸盐工业]