Vacuum brazing of the Cf/C composite and Ni base superalloy using MBF 20 filler

Carbon fiber reinforced carbon matrix (Cf/C) composite and Ni base superalloy were brazed in vacuum using MBF 20 filler. By varying brazing temperatures and holding times, the effects of brazing parameters on the microstructure as well as its evolution and mechanical properties of the joints were investigated. The results show that the microstructural evolution of joints experiences three stages. With the rising of brazing process parameters, the dissolution of Cf/C turns strong, leading to the formation of rough composite/filler interface and the increasing of amount of Cr7C3 and MC complex metal carbides. The residual stress concentration in joint changes consequently. The maximum shear strength of the joint can reach 35 MPa (which is up to 92% of the shear strength of Cf/C substrate), 15 MPa and 9 MPa at room temperature, 800 °C and 1000 °C, respectively. The fracture initiates and propagates in Cf/C composite.