Microstructure refinement and mechanical enhancement of SiC_f/SiC brazed joints mediated by cold-sprayed Cu-Ti-TiC composite interlayer

A novel strategy combining cold spray additive manufacturing (CSAM) with brazing was developed to overcome particle agglomeration and enhance the mechanical properties of SiC_f/SiC composite joints. Cu-Ti-TiC composite interlayers with different TiC volume fractions were fabricated via CSAM, and their effects on microstructure evolution and shear strength of the brazed joints were systematically investigated. A comparative analysis between CSAM-assisted brazing and conventional powder brazing was conducted, and the formation mechanism of the brazed joint was elucidated. Experimental results demonstrated that CSAM facilitated the uniform distribution of TiC particles within the brazing seam, effectively preventing the agglomeration defects commonly observed in conventional brazing. Notably, when the TiC volume fraction in the spray powder reached 40%, the brazed joints exhibited a shear strength of 81.3 MPa, significantly surpassing the 28.3 MPa of conventional powder-brazed joints. During brazing, controlled interfacial metallurgical reactions generated dispersed TiSi₂ second-phase particles. These particles synergistically interacted with TiC, suppressing grain coarsening in the brazing seam and substantially enhancing the overall mechanical performance of the joints. This work provides a new technical route for optimizing the brazing process of ceramic matrix composites, offering both experimental and theoretical insights for designing high-performance composite brazing interlayers.