Brazing of ZrB2–SiC–C ceramic and GH99 superalloy to form reticular seam with low residual stress

Abstract

In this study, Ag–Cu–Ti/Cu mesh/Ag–Cu–Ti composite foils were designed to braze ZrB2–SiC–C (ZSC) ceramic and GH99 superalloy, and sound brazed joints were obtained. The interfacial microstructure and mechanical properties of the brazed joints were investigated. By comparing joints brazed with Ag–Cu–Ti filler alloy and Ag–Cu–Ti/Cu foil/Ag–Cu–Ti composite foils, the mechanism by which Ag–Cu–Ti/Cu mesh/Ag–Cu–Ti composite foils improves the shear strength of the joint was assessed. Due to the application of a Cu mesh, a reticular braze seam with enhanced ductility was fabricated, which can inhibit the formation of Ti–Cu intermetallic compounds in the braze seam and decrease the thickness of the Ti3SiC2 layer adjacent to ZSC. As a result, the residual stress concentration in a brazed joint can be reduced. Using Ag–Cu–Ti/Cu mesh/Ag–Cu–Ti composite foils, the maximum shear strength of the brazed joints increased to 121MPa, which is 560% of the joints brazed with Ag–Cu–Ti filler alloy (21MPa).