Microstructure Analysis of SiC Ceramics and SiCf/SiC Composites by Diffusion Bonding

摘要

With the excellent high temperature performance and irradiation stability, the SiCf/SiC composites are considered as a kind of promising new fuel cladding material. The joint between the end plug and cladding is one of the key problems affecting its application. In this research, the connection between SiCf/SiC composites was realized by diffusion bonding, and the microstructure and reaction products in the joint area were analyzed by SEM and XRD. The results showed that continuous dense interface layer could be formed at the junction by the chemical reaction between Ti and silicon carbide, and the interface reaction products were TiC and Ti_5Si_3. The interface layer formed a sawtooth structure at the junction with SiCf/SiC composites. The chemical reactivity of the SiC fiber was weaker than that of the substrate, and there were gaps in the interface layer, which limited the diffusion of the interface reaction to the composite materials. There were long and thin interfacial phases in the pores of the materials, which formed strong mechanical occlusion with the SiCf/SiC composites and improved the degree of interfacial layer bonding.