Research progress on brazing of advanced functional materials

Taking multiphase ceramics, fiber reinforced ceramic matrix composites and thermoelectric materials as examples, this paper discusses the researches published in recent years which focused on the composition design of filler metals, microstructure controlling of brazed interface, residual stress mitigation of brazed joints and performance evaluation of brazed joints. The results show that the wettability and interfacial bonding strength can be improved effectively by adding active elements to filler metals or modifying the surface of base metal. For the element diffusion of interface and the transitional dissolution of base metal, composite filler metals or barrier layer can be designed and prepared to solve these problems. The residual stress of brazed joint is greatly affected by the difference of thermal expansion coefficient of brazing materials. At present, various novel solutions have been proposed, such as adding porous interlayer, preparing gradient composite layer and machining of base metal surface. However, the application of research results is still limited to small size samples. The problem of relieving the residual stress of large size joints remains to be solved. Ultimately, the prospect of the interest in future research is concluded. It is expected to promote the domestic manufacturing of aerospace and weapons equipment.