Joining of Cf/SiC composites and Si3N4 ceramic with Y2O3-Al2O3-SiO2 glass filler for high-temperature applications

Cf/SiC composites and Si3N4 ceramics are candidate materials for applications in thermal protection system. This paper investigated the joining of Cf/SiC and Si3N4 using Y2O3?Al2O3?SiO2 glass. The reliability of joints was evaluated by thermal shock tests. In this present work, the typical joint structure was Cf/SiC-glass-Si3N4. The results demonstrate that Direct bonding has been identified as the interfacial bonding mechanism at the SiC/glass and glass/Si3N4 interfaces. The maximum shear strength of the Cf/SiC?Si3N4 joint was -34 MPa, which delivered an effective method to achieve strong, reliable bonding between the dissimilar materials. In addition, after thermal shock for 10 cycles, the residual strength remained -13 MPa. Bubbles instead of microcracks formed in the glass filler, which was the main factor causing the degradation of the joint performance. It is suggested that improving the high temperature resistance of joining materials is the key to realize the application of this joint structure.