Improved the mechanical properties of silicon carbide fiber reinforced silicon carbide matrix composite joints by short-time diffusion bonding with Nb-Ti-Si alloy filler

Advanced joining technology is crucial for promoting the engineering applications of silicon carbide fiber reinforced silicon carbide matrix composites (SiC_f/SiC). In this study, the (Nb_0.3Ti_0.7)_1-xSi_x (x = 0.02, 0.05, 0.1, 0.15) alloy fillers were prepared by spark plasma sintering (SPS), which were used to perform short-time diffusion bonding of SiC_f/SiC composites in a vacuum sintering furnace without equipment pressure. The effects of different alloy fillers and holding time on the properties of joints were systematically studied. When the Si content in the alloy filler reaches 0.10, the joining layer is the densest. This is attributed to the formation of liquid phase in the alloy filler during diffusion bonding, which promotes the densification of the joining layer. Under the conditions of 1500 °C and holding time for 30min, the SiC_f/SiC composites and alloy filler undergo moderate diffusion reactions and obtain the shear strength of 52.4±7 MPa. This work helps promote the long-term application of SiC_f/SiC composite joints in high temperature environments.