Vacuum Brazing of SiC Ceramic and 316L Stainless Steel

The SiC rod (Ф15 mm×15 mm) and 316 L stainless steel disc (Ф15 mm×5 mm) were firmly jointed by vacuum brazing with AgCuTi alloy filler. The influence of the brazing temperature, holding time and interface properties on the phase-structures and bonding strength at the joints was investigated with X-ray diffraction, energy dispersive spectroscopy, scanning electron microscopy and mechanical tools. The results show that the brazing temperature, holding time and interface properties all had a major impact. For example, the shear fractures often occurred at the SiC/alloy-filler interface, where highly active Ti induced formation of a continuous reaction layer, mainly comprising Ti C and Ti₅Si₃ phases; in contrast, at the interface of stainless steel and alloy-filler, the intermetallics of Fe-Ti and Cu-Ti formed. Brazed at 900℃ for a holding time of 20 min, the joints displayed the strongest shear strength.