Progress Research on the Interlayer Assisted Brazing of Ceramic and Metal to Relieve Residual Stress

Great residual stress will appear in the ceramic and metal joint in the process of braze welding due to the great difference of the thermal expansion coefficient (CTE) between the two materials, therefore, the strength of the joint decreases. Introducing the interlayer is one of the most simple and efficient methods to relieve the residual stress of the joints. In this study, the characteristics of introducing interlayer assisted brazing are analyzed from two aspects. One is to improve the plastic toughness of the soldering seam; the other is to make the joint form a good gradient transition of CTE. The research status of Cu foil interlayer, 3D-SiO₂-fiber interlayer, foam metal interlayer (foam Cu, foam Ni, and foam stainless steel) and porous SiC ceramic for relieving residual stress is reviewed. The effect of microstructure optimization of the braced joint on the mechanical properties of the joint is introduced. The development of interlayer assisted ceramic metal brazing is prospected and the research is hoped to provide reference for the development and technical breakthrough of the brazing between ceramic and metal.