Microstructure and properties of C/C and C/SiC composites brazed by reactive infiltration of Si - Zr filler alloy

The joint between C/C composites and liquid silicon infiltrated-C/SiC composites was achieved using a Si - 10Zr (at. %) eutectic filler. The microstructure and mechanical properties of joints at different brazing temperature and holding time were characterized. The results showed that the melting filler infiltrated along the carbon fiber bundle gaps and formed SiC reaction layers at both interfaces. On the side of C/SiC composites, the residual silicon in the original base material dissolved into the molten Si - 10Zr alloy during the brazing procedure. The phenomenon resulted in intense infiltration of the liquid filler into C/SiC composites, which formed a unique C/ SiC-Si-ZrSi 2 multiphase -ceramic gradient structure. Excessive filler was squeezed out around the joint seam to form a fillet. The shear strength of the joint reached up to 37 MPa, with fracture occurrence in both substrates and the joint seam. Reliable bonding between C/C and C/SiC dissimilar composites was finally achieved.