Effect of the B4C particles on the brazed joints of SiC ceramics and 2219 aluminum alloy

Abstract

A two-step process, including the premetallization of the SiC ceramic by Ag-26.7Cu-4Ti+B₄C and the followed brazing with the Al-based filler alloy, was developed to join 2219 aluminum alloy and the metallized SiC. The influence of metallization temperature and the B₄C addition on the microstructure and mechanical properties of the joint was analyzed. The reaction products of Ti and B₄C were detected in the brazing seam, such as Ti₂B, TiC and graphite. With increasing of metallization temperature and B₄C addition content, the shear strength of joint first increased and then decreased. The joint shear strength reached 14.0 MPa when SiC metallized with Ag-26.7Cu-4Ti+1%B₄C at 930°C for 10 min, which showed that appropriate addition of B₄C in Ag-26.7Cu-4Ti metallization layer could regulate the coefficient of thermal expansion difference between 2219 aluminum alloy and SiC to relieve the residual stress and improve the shear strength of their brazed joint.