采用Ti/Ag/Ti中间层连接SiC陶瓷的 有限元应力分析

在陶瓷与金属或陶瓷与陶瓷(采用金属中间层)的连接过程中,陶瓷与金属的热膨胀系数等性质存在差异而产生的残余热应力是连接接头强度弱化的主要原因.采用有限元方法对Ti/Ag/Ti作为中间层热压连接SiC陶瓷进行了应力的有限元计算分析,结果表明采用Ti/Ag/Ti结构的金属中间层连接SiC陶瓷时,对接头危害较大的残余应力主要分布在连接件近缝区.靠近试样外表面区域是接头的薄弱区,裂纹易在此处萌生,裂纹的扩展先是沿着一条向陶瓷侧凹入的弧线向陶瓷内切入,而后沿径向扩展.接头实际断裂方式与有限元分析结果相符,表明采用有限元方法对陶瓷连接接头的残余应力进行模拟计算有重要的指导意义. 

Analysis of the residual thermal stresses of SiC joint with Ti/Ag/Ti interlayer by FEM

With regard to the joining of ceramic to ceramic using metallic interlayers or the joining of ceramic to metal, the mismatch of thermal expansion coefficient between the ceramic and the metallic materials generates residual thermal stresses during joining and cooling. The stresses may cause microcracks leading to low weld strength and even failure of joining. The residual thermal stresses of SiC joint with Ti/Ag/Ti interlayer were analysized by finite element method(FEM). The results indicate that the residual thermal stresses mainly distribute in the area near the welding seam. The area close to the outer surface and near the welding seam is the weakest area of the joint, where cracks are likely to be initiated. The fracture position of the joint indicated by the FEM analysis is in accordance with the result of experiment.