Achieving robust joining in ZrC–SiC composite via heterogeneous architecture and full-ceramic strategy

Reliable joining of ZrC–SiC composite is significantly restricted by the incompatible interface between the ceramic substrate and the metallic seam. To resolve this issue, a full-ceramic joint with heterogenous carbides was achieved by pulsed-current assisted diffusion bonding. During joining, the designed Ti–Zr–Ti sandwich interlayer quickly formed (Ti, Zr) solid solution by inter-diffusion, which reacted with SiC to produce (Ti, Zr)₅Si₃C. Above 1350 °C, the reaction of (Ti, Zr)₅Si₃C and (Ti, Zr) triggered local melting, (Ti, Zr) transformed into heterogenous carbides in the seam center, but the liquid infiltrated into composite and formed a brittle reaction layer, limiting the enhancement of joint performance. Replacing the interlayer by an alloyed Ti_0.75Zr_0.25 foil, the penetration of Ti-rich liquid was significantly inhibited, and the decrease in viscosity at elevated temperature facilitated the liquid extrusion. Consequently, a full-ceramic interface of heterogenous ZrC_x(Ti) and TiC_x(Zr) was obtained at 1450 °C for 20 min, and the brittle reaction layer was eliminated. Attributed to the good physical and chemical compatibility between the seam and the substrate, the joint exhibited a superior shear strength of 286 ± 49 MPa, which is comparable to that of the substrate. This study demonstrates the heterogeneous and full-ceramic design capable of achieving superior joint of ZrC–SiC composite.