Microstructure and mechanical strength of SiC joints brazed with Cr3C2 particulate reinforced Ag-Cu-Ti brazing alloy

Abstract

Joining of SiC ceramic with Ag-Cu-Ti active alloy reinforced with Cr3C2 particulates to control the microstructure and increase joint strength was investigated. The results indicated that the reaction of titanium in the brazing alloys and Cr3C2 particulates was detected, but it would not affect the reaction of Ti and SiC. TiC reaction layer with a thickness about 100 nm was formed at the interface between SiC ceramic substrate and brazing alloy. Ti5Si3 silicide phases were also observed near the reaction layer. The Cr3C2 particulates randomly distributed in the braze matrix (< 10 vol% Cr3C2) and refined the Ag-rich and Cu-rich solid solution phase. Cu2Ti intermetallic phase was also found in the joint. The clustering and particle-to-particle contact behavior of Cr3C2 particulates was observed in the joint with high amount of Cr3C2. The joint strength increased with increasing the volume fraction of added Cr3C2 particulates first and then decreased. The shear strength of the joint brazed with 10 vol% Cr3C2 addition reach up to 212.8 MPa, which was 134.2 MPa higher than that brazed with Ag-Cu-Ti brazing alloy.