Interfacial reaction and brazing behaviour of SiCf/SiC with Cf/C composites using Si-10Zr alloy at high temperatures

Abstract

A Si-Zr eutectic alloy was employed as a high-temperature braze filler to join SiCf/SiC composites with Cf/C composites. The interfacial microstructure and bonding mechanism on the side of the SiCf/SiC composites were studied for the first time. The results showed that SiC reaction layers formed between the Si-Zr filler and both substrates. The SiC layer resulted from the chemical reaction between Si and C at the filler–Cf/C interface. In contrast, at the filler–SiCf/SiC interface, coarse-SiC crystals only precipitated on the SiC fibre bundles, and there was only non-reactive bonding between the filler and the SiC matrix. In addition, the reactive infiltration process between the liquid Si alloy and the porous substrates contributed to the formation of infiltration structures, including Cf/C–SiC and SiCf/SiC–Si-ZrSi2, resulting in the reinforcement of the substrates and the joint. Finally, a favourable shear strength of 38 MPa was achieved.