Brazing of surface modified C/C composites to Ni-based superalloy for high temperature applications

Abstract

In this paper, brazing of high reliability C/C composites-metal joint for high temperature application was studied. The surface of C/C composites was modified by Cr metallization process and then brazed to Ni-based superalloy by AgPd braze. Alumina block was used as interlayer and a zig-zag interfacial structure was constructed at the composites/braze interface. The results show that, after the metallization process, a strong adhesion reaction layer consisting of Cr carbides was coated on the C/C surface which in turn obviously improved the wettability of braze. The molted braze filled completely into the laser machined holes in C/C substate and well-bonded interfaces and homogeneous Ag(Pd) solution microstructure was obtained in the joint. The strength of joint with C/C metallized at 1100℃ is higher than that of joint with 1300℃. The joints exhibit very high bending strength up to 82 MPa and shear strength up to 54 MPa, respectively. The braze spikes increase the connection area and provide strong pinning effect.