Microstructural evolution and joining mechanism of Cf/SiBCN ceramic joints brazed with Ti-Ni filler metal

C_f/SiBCN ceramics have been joined using Ti-Ni high temperature filler metal. The influence of composition of solder, the laminated form of solder and the brazing temperature on the interfacial microstructure have been studied. It has been found that a good interface can be obtained when the content of Ni was over 50% and the laminated form was Ni/Ti/Ni. The Ni element diffused into the ceramic substrate and reacted with Si element, a diffusion layer has been formed in the ceramic, thus a gradient distribution of Ni, Si element within the diffusion layer was obtained, while Ti element dispersed in the middle of the filler layer in the form of compound. The experimental results revealed that increasing the brazing temperature is beneficial to the diffusion of Ni element. When the laminated form of solder was Ni/Ti/Ni, the content of Ni was lower than 50%, and the brazing temperature was increased to 1 300 ℃, a joint without significant crack can be obtained, and the distribution of Ti compound in the middle layer was more dispersed.