Mechanical Properties of Diffusion Bonding Joint of SiC and Al-Sn Alloys at Elevated Temperatures

Abstract

Aluminum alloys were selected to bond to SiC by diffusion bonding in the atmosphere for researching their bondability. Diffusion bonding was carried out at 873 K for 3.6 ks and 7.2 ks under bonding pressures of 2 MPa, 4 MPa and 8 MPa. The mechanical properties of SiC/Al–0.5Sn joints and SiC/Al–0.5Sn–1Mg joints at elevated temperatures were examined by shear test, and the fracture surfaces of joints were investigated using SEM and EPMA . The results indicate that (1) pure aluminum cannot be bonded to SiC . Adding 0.5%Sn into aluminum can improve bondability. The compound addition of 0.5%Sn and 1%Mg into aluminum can improve both the shear strength and the elevated temperature properties of joint. (2) In the case of SiC/Al–0.5Sn diffusion bonding, the fracture fully occurs on bonding surfaces. In the case of SiC/Al–0.5Sn–1Mg diffusion bonding, the fracture partly occurs in the side of SiC . (3) The optimum bonding pressure is 4 MPa and 8 MPa for SiC/Al–0.5Sn and SiC/Al–0.5Sn–1Mg diffusion bonding, respectively. In optimum bonding condition, the maximum shear strength of SiC/Al–0.5Sn–1Mg joint is 51.7 MPa.