TiZrNiCu钎焊(Cf-SiCf)/SiBCN与Nb的界面产物及机理分析

Microstructure evolution and joining mechanism of brazing (Cf-SiCf)/SiBCN to Nb with TiZrNiCu

关键词:  超高温陶瓷  非晶钎料  界面组织  连接机理

Key words:  ultra-high temperature ceramic  amorphous solder  interface structure  joint mechanism

摘要:

采用TiZrNiCu钎料来实现改良的超高温陶瓷（C_f-SiC_f）/SiBCN与金属Nb的钎焊连接，研究了温度、时间对界面组织及力学性能的影响规律，对连接机理进行了分析. 结果表明，在900 ℃/20 min的工艺参数下，（C_f-SiC_f）/SiBCN-Nb接头室温抗剪强度最高达到36 MPa，接头典型的界面结构为Nb/Ti-Nb固溶体/（Ti， Zr）₂（Cu， Ni）/Zr₅Si₃ + Ti₅Si₃/TiC + ZrC/（C_f-SiC_f）/SiBCN. Cu元素在钎焊过程中逐渐从钎料扩散陶瓷母材中，通过与SiC反应生成Cu-Si脆性化合物进一步促进（C_f-SiC_f）/SiBCN陶瓷的分解，同时Cu-Si相是接头断裂路径由钎料层扩展到陶瓷侧的主要原因；保温时间过高时，陶瓷的分解程度增加，接头断裂在陶瓷内部；而温度过高时，固溶体前端与钎料层物相差异增大而引起了贯穿钎料层的裂纹.

Abstract:

In this work, TiZrNiCu was proposed to realize the joining of the improved high temperature ceramic (C _f-SiC_f)/SiBCN and Nb. The effects of brazing temperature and holding time on interface microstructure and mechanical properties were investigated, and the joining mechanism was detailed described. The joint shear strength reached maximum of 36 MPa at 900℃/20 min, in which typical interface structure was SiBCN/TiC+ZrC/Ti ₅Si₃ +Zr ₅Si₃/(Ti,Zr) ₂ (Cu,Ni)/(Ti-Nb)ss/Nb. During the brazing process, Cu-Si brittle compounds were formed in the ceramic by infiltration of Cu into the (C _f-SiC_f)/SiBCN, responsible for the fracture path extended from the solder layer to the ceramic side in most cases. When the holding time was 30 min, the joint was directly broken on the ceramic base material due to the excessive penetration effect of Cu; at excessive temperature, the fracture occured in the filler, since the large difference between the (Ti-Nb)ss and the solder materials.