Vacuum Brazing between SiCp/Al Composites after Surface Nickel Plating and Kovar Alloy

The microstructure and shearing fracture morphology of the vacuum brazed joint between the SiCp/6063Al composites with 55vol.% of SiC particles after nickel plating on their surface and Kovar alloys were studied by means of scanning electron microscopy and shearing testing. The effects of soaking time on the microstructure and property of the joint were also investigated. The results show that the SiCp/6063Al composites after surface nickel plating could be jointed together with Kovar alloys by means of vacuum brazing technique. The joint with shear strength of 100 MPa was achieved at the brazing temperature of 550 ℃ and soaking time of 20 min, which showed typical brittle fracture. The element Ti from the brazing filler metal reacted with SiC particles in the SiCp/6063Al composites, resulting in a metallurgical bonding between the filler metal and base material. The microstructure of weld metal was quite compact since the brazing filler metal can wet the Kovar alloy and SiCp/6063Al composites after nickel plating very well.