Improved shear strength of SiC-coated 3D C/SiC composite joints with a tailored Ti-Si-C interlayer

SiC-coated 3D C/SiC composites were successfully joined using SPS technology with a Ti-Si-C interlayer. The interface morphologies, phase composition, and mechanical properties of the joints were investigated in detail. By adjusting the joining temperature, the interlayer transitioned, in situ, from Ti-Si-C compounds to Ti₃SiC₂ grains without decomposition. Because of the plastic deformation behavior of Ti₃SiC₂ grains, the ability of the interlayer to inhibit crack propagation increased. For joints with different interlayer thickness, the distribution of thermal residual stress was calculated using finite element analysis, and the distribution was associated with the evolution of interlayer morphologies, which was eventually used to establish fracture models. Optimized bonding was achieved without erosion of carbon fibers and also without interfacial defects. Finally, a reliable joint with shear strength of 51 ± 3.0 MPa was obtained by precisely controlling the interlayer reaction and optimizing thermal residual stress.