The Effect of Surface Treatment on the Resistance Welding Technology for Carbon Fiber/Epoxy Resin Composites

In this research, a high-efficiency joining technique of resistance welding is proposed to achieve high-quality joining of carbon fiber/epoxy (CF/Epoxy) composites. The effects of mechanical sanding and dielectric barrier discharge (DBD) plasma surface modification were investigated on joint properties. Through morphology observation, wettability research, and surface chemical element analysis, it was found that both methods effectively improved joint performance. Mechanical sanding increased surface roughness, facilitating mechanical interlocking between composite layers. DBD plasma treatment enhanced surface wettability, promoting better adhesion between the materials. Notably, the failure mode of the welded joint transformed from interface failures to interlayer failures, indicating improved joint integrity and strength. The combined treatment method, using both mechanical sanding and plasma treatment, yielded the highest single lap shear strength (LSS) of 25.78 MPa, which was an impressive 141.2% higher than the untreated sample.