AgCuTi/graphene-reinforced Cu foam: A novel filler to braze ZrB₂-SiC ceramic to Inconel 600 alloy

In order to relieve high residual stresses between ceramics and metals during brazing processes, an AgCuTi/graphene-reinforced Cu foam composite filler was developed and used to braze the ZrB₂-SiC ceramic and Inconel 600 alloy. Microstructures and shear strengths of the joints were systematically studied. The joints are composed of TiFe₂, TiCu, TiC, Cu(s, s), Ag(s, s), and Ti₅Si₃ phases. It is found the addition of graphene on the Cu foam surface can effectively retard diffusions of metal atoms and avoid the collapse of the foam matrix. After being brazed at 900 °C, the joint can get a maximum shear strength of 157 MPa, much higher than those brazed without graphene addition. The high shear strength was investigated in detail and attributed to the integrity of the Cu foam, formation of the TiC and thickness of the reaction layer at the ceramic side.