Wetting of Si–14Ti alloy on SiCf/SiC and C/C composites and their brazed joint at high temperatures

Abstract

The wetting and joining of SiCf/SiC composites and C/C composites with a high-temperature Si–14Ti (at. %) braze filler were studied for the first time. Wetting dynamics and the contact angle were investigated by heating the Si–Ti sessile droplets on the SiCf/SiC and the C/C substrates. The interfacial micromorphology, shear strength, and fracture characteristics of the joints were all analysed. The Si–Ti alloy had contact angles of ~23° on the C/C and ~7° on the SiCf/SiC at 1460 °C, demonstrating excellent wettability on both substrates. SiC reaction layers were formed at both interfaces of the joint. The reactive infiltration into both substrates occurred during the brazing process, especially in the SiCf/SiC composites. The infiltration structures and the robust bonding were conducive to strengthening the brazed joint. The joint exhibited optimal shear strength values of 31 MPa at room temperature and 40 MPa at a high temperature of 1000 °C.