Investigation of the effect of silver on diffusion welding of copper matrix composite materials

In this study, silicon carbide reinforced silver added copper matrix composite materials were produced by powder metallurgy method. For the production of composite materials, copper powder was reinforced with 5% and 10% SiC by volume and copper matrix composite materials with a diameter of 15 mm and a height of 15 mm were obtained. Silver powder was added to the 1.5 mm end parts of each sample at the rates of 2%, 4% and 6% and pressed by cold pressing method under 600 MPa uniaxial pressure and then sintered at 850 °C for 120 minutes. At the end of the process, the silver added parts were joined by diffusion welding method under Argon atmosphere using 850 °C temperature, 2 MPa pressure and waiting times of 30, 60 and 120 minutes. Three-point bending tests were performed to determine the interfacial strength of the welded joints. In addition, the joint line of Ag-Cu-SiC welded joints were analysed using optical microscope and scanning electron microscope (SEM). EDS analysis was performed to confirm the presence of silver in the analyses. As a result of three-point bending tests performed on the welded specimens, it was determined that the bending strength increased with increasing silver content. The best result in transverse rupture strength values was measured as 156.74 MPa in the sample with 10% SiC reinforcement and 6% Ag addition at 120 minutes welding time. As a result of the hardness measurements, it was determined that the added silver increased the hardness values. The highest hardness value after welding was determined to be in the sample containing 10% SiC reinforced and 6% silver by volume, which was welded for 120 minutes. The increase in the amount of silver added to the structure showed an increasing effect on the joint strength values at low welding times. It was observed that the effect of silver at 10% SiC reinforcement ratio provided more effective joint strength than 5% SiC reinforcement ratio. The best results were obtained in the specimen with 10% SiC reinforcement and 6% Ag addition welded at 120 minutes welding time.