Vacuum brazing of SiBCN ceramic and TC4 alloy using TiB2 reinforced AgTi composite filler

In this study, the SiBCN ceramic and TC4 alloy were successfully brazed using TiB2 reinforced AgTi composite filler in a vacuum furnace. The typical interfacial microstructure of the joint and the reaction products were identified through EDS, SEM and XRD. The effect of the TiB2 content and brazing temperature on the joint microstructure and property were investigated. During the brazing process, the filler reacted with the SiBCN to form TiC + TiB + TiN + Ti5Si3 reaction layer adjacent to the SiBCN. With the increase of the TiB2 content in the composite filler, the diffusion of Ti in the brazing seam was restrained, and the reaction layer became thinner. Meanwhile, the TiB2 volume fraction in the brazing seam increased. The increase of the brazing temperature promoted the reaction of the braze filler and the base materials. Thick reaction layer adjacent to the SiBCN and lots of Ti (s.s) and Ti2Ag in the brazing seam were obtained at high brazing temperature. When the SiBCN and TC4 were brazed using 6 wt% TiB2 reinforced AgTi composite filler at 980 °C for 10 min, the maximum shear strength of the joint reached 32 MPa.