氧化铝/莫来石复合陶瓷断裂行为研究

用X射线衍射方法测定了氧化铝/莫来石复合陶瓷的残余应力,并通过计算加以验证。在莫来石含量比较小的情况下,氧化铝/莫来石复合陶瓷基体拉应力与莫来石体积含量成线性关系。通过模型分析了氧化铝基体和莫来石颗粒的应力状态及其对裂纹扩展的影响。由莫来石颗粒引入的基体拉应力使裂纹倾向于向晶内扩展。观察了氧化铝/莫来石复合陶瓷断裂方式的转变,计算了穿晶断裂比率与基体应力的关系,进而建立了莫来石含量、基体应力、穿晶断裂比率三者的对应关系。这为复合陶瓷材料的制备和性能分析提供了可靠基础。

THE RESEARCH ON FRACTURE BEHAVIOR FOR ALUMINA/MULLITE COMPOSITES

Residual stresses in alumina/mullite composites were measured by X-ray diffraction and the resultant values were validated by calculating. The residual stresse was in linear relation with the mullite content when it was low. The residual stresses in the alumina matrix and on the mullite particles as well as their effect on crack growth were analyzed by modelling. The tensile stress in matrix introduced by mullite particles made the cracks incline to extend into the matrix. Transition of fracture mode was observed and the percentage of transgranular fracture (PTF) as a function of the matrix stresses was figured out. The coincidence relation of mullite content, matrix stresses and PTF was then established. The results provide some basic foundation for preparation and property studying for ceramic composites.