A novel approach to brazing C/C composite to Ni-based superalloy using alumina interlayer

C/C composite was brazed to a Ni-based superalloy using an active AgCu braze with an alumina ceramic interlayer and/or a zig–zag interfacial structure between the C/C and the braze. The joint with the Al2O3 interlayer displayed perfectly bonded interface and ductile joint microstructure because the diffusion and chemical reactions of Ni and Ti are prevented, which in turn improved the joint strength due to the reduced residual stress. Moreover, the joint was significantly strengthened and toughened by the proposed zig–zag interfacial structure. The strengthening mechanism was attributed to the enlarged joining area, reduced residual stress and strong pinning effect of the braze spikes. A quite high bending strength of 73 MPa was obtained from the C/C-superalloy joint with the zig–zag interfacial structure.