Joining of Cf/SiC and stainless steel with (Cu–Ti)+C composite filler to obtain a stress-relieved and high-temperature resistant joint

In this study, to obtain a stress-relieved and high-temperature resistant joint of Cf/SiC composite and stainless steel at relatively lower brazing temperature, reaction composite-diffusion brazing with the mixed powders of Cu–15Ti alloy and C particles as filler material was used to join Cf/SiC composite and nickel-plated stainless steel. Results show that C particles reacted with Cu–Ti alloy filler with low melting point not only formed a composite joining layer which can relieve residual stress in the joints, but also formed a heat resistant (Cu)ss matrix due to the consumption of the melting point depressant element Ti. Meanwhile, the nickel plating diffused melting raising element Ni into the joining layer formed a (Cu,Ni)ss matrix with higher heat resistance, further improving the heat resistance of the joining layer, so the filler isothermally solidified in a short time during the brazing process. In addition, the nickel plating also prevented the formation of the brittle compound TiFe that may cause crack at the interface of joining layer/stainless steel. As a result, a stress-relieved joint with high-temperature resistance was obtained at relatively lower brazing temperature, and the maximum shear strength of the joint reached 233.4 ± 21.3 MPa, which is 51.3% higher than that brazed with Cu–15Ti alloy alone.