Joining of Cf/SiBCN composite with CuPd-V filler alloy

Two compositions of CuPd-V system filler alloy were designed for joining the Cf/SiBCN composite. Their dynamic wettability on the Cf/SiBCN composite was studied with the sessile drop method. The CuPd-8V alloy exhibited a contact angle of 57° after holding at 1170 °C for 30 min, whereas for CuPd-13V alloy, a lower contact angle of 28° can be achieved after heating at 1200 °C for 20 min. Sound Cf/SiBCN joints were successfully produced using the latter filler alloy under the brazing condition of (1170-1230)°C for 10 min. The results showed that the active element V strongly diffused to the surface of Cf/SiBCN composite, with the formation of V2C/VN reaction layer. The microstructure in the central part of the joint brazed at 1200 °C was characterized by the V2C/VN particles distributing scatteringly in CuPd matrix. The corresponding joints showed the maximum three-point bend strength of 82.4 MPa at room temperature. When the testing temperature was increased to 600 °C, the joint strength was even elevated to 108.8 MPa. Furthermore, the joints exhibited the strength of 92.4 MPa and 39.8 MPa at 800 °C and 900 °C, respectively.