结构防护材料Al_(2)O_(3)/SiC陶瓷的动态拉伸力学性能

Dynamic Tensile Mechanical Properties for Structure Protection Material of Al_(2)O_(3)/SiC Composite

设计巴西圆盘试验获得了Al_(2)O_(3)/SiC复合陶瓷动态拉伸力学性能参数值,采用扫描电子显微镜分析了微观断裂机理。试验结果表明,材料失效具有脆性典型特征,其动态抗拉强度随应变率的增加而增加。回收圆盘试样发现宏观破碎模式主要呈“川”字型,主裂纹沿加载路径方向。断面微观分析发现,材料除了存在具有锋锐边缘的沿晶断裂区域,还存在许多穿晶断裂区域以及晶粒边界微裂纹。断裂面存在单个晶粒扭曲和劈裂形成的细小碎片,且在平面外剪切应力作用下形成了台阶状和舌状的微观解理断裂区域。

The Brazilian disc experiments were designed to obtain the dynamic tensile mechanical properties of the Al_(2)O_(3)/SiC composite ceramic.The micro-fracture mechanism of composite was analyzed by the scanning electron microscope.Experimental data showed that the failure of the composite had a typical brittle characteristic.And its dynamic tensile strength was increased with the increasing of strain rate.Recycled Brazilian disc showed that the macro fracture mode of specimen included three vertical cut-through cracks.And the main crack was propagated along the loading direction.The micro-fracture surface analysis showed that the composite exited sharp-edged intergranular fracture region,transgranular fracture regions and microcracks of grain boundaries.The fractured face has many distortion of single grain,tiny fragments by tensile splitting.The shear stress of out-plane resulted in the step and tongue shape of cleavage fracture region.