In situ TiSi₂ microarray reinforced Si–Ti eutectic colonies in C_f/C composite joints for high-temperature application

A novel type of brazed joint with in situ TiSi₂ microarray strengthened Si–Ti eutectic colonies in a carbon fibre reinforced carbon (C_f/C) composite was developed. The mechanical properties, microstructure evolution, fracture characteristics, and interfacial reaction mechanism of the joint were investigated. The shear strength of a pressure-less brazed joint can reach 41 MPa, which is comparable to other current joints developed under a certain pressure. Both the eutectic phases with uniform TiSi₂ sticks in the brazing seam and Si–Ti melt infiltration throughout the porous C_f/C composite are conducive to relieving the thermal residual stress in the joining system. With more melt filling and a higher reaction with the porous C_f/C substrate, an in situ TiSi₂ microarray reinforced SiC/carbon assembly is formed and the mechanical properties of the joint are significantly improved. In addition, an excellent high-temperature shear strength of 46 MPa is achieved at a test temperature of 1000 °C in air. Moreover, a thermal shock test leads to the generation of cracks in the brazing seam and the interface regions, which is a hindrance the joint strength.