Brazing of C/C composite and GH99 superalloy Using BNi2+TiH₂ composite filler powder

The brazing of C/C composite and GH99 nickel base superalloy was successfully performed using BNi2+TiH₂ brazing powder. The interfacial microstructure and mechanical properties of the brazed joints were investigated. The results show that,the typical microstructure of the joint is:C/C composite/Cr₃C₂+MC+Ni(s,s)/MC+Ni(s,s)/Ni₃Si+Ni(s,s)/Cr₃C₂+MC+Ni(s,s)/GH99. With the increasing of content of TiH₂,the dissolution of C/C substrate was enhanced,dispersed MC carbide particles formed in braze seam,and the modulus mismatch between C/C and filler alloy,the mechanical properties of the brazed joints were improved consequently. When using braze powder with 3% TiH₂ addition, the maximum shear strength of the brazed joints were obtained,which were 40 MPa at room temperature,19 MPa at 800℃ and 10 MPa at 1 000℃. Comparing with brazed joints using BNi2 filler alloy,BNi2+TiH₂ joints possess higher strength,and the high-temperature properties of the joints can be guaranteed.