Root-like C/SiC surface structure fabricated by the thermal and electrochemical corrosion for brazing to Nb

Root-like structure on C/SiC surface has been designed through selective corrosion to decrease the residual stress and then to optimize the microstructure when brazed to Nb. Thermal and electrochemical corrosion are conducted to diminish the SiC matrix and the interface between carbon fibers and SiC, respectively. The surface structure can be filled with brazing alloy characterized by the gradient layer of carbon fiber reinforced brazing alloy. Compared with thermal corrosion, SiC particles and nano Ti₅Si₃ are uniformly dispersed throughout the gradient layer in electrochemical corrosion. The layer decreases the difference in property consequently to relieve the residual stress. In addition, the original reaction layer will be replaced by this layer, favorable for the increase in joining strength and fracture toughness. The brittle facture at the reaction layer in original joints can be transformed into the zig-zag path. The shear strength of joints with the thermal and electrochemical corrosion depth of 100 μm increases to 151.6 MPa and 164.3 MPa, respectively, which is 77% and 92% higher than that of original joints.