Influence of surface modification of carbon fiber based on magnetron sputtering technology on mechanical properties of carbon fiber composites

To improve the interfacial performance of carbon fiber (CF) and epoxy resin, the surface of CF was modified using magnetron sputtering technology, and a CF epoxy resin (CFER) composite was prepared using injection molding technology. The influence of magnetron sputtering technology on the surface properties of CF was investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), and dynamic contact angle analysis (DCAA). The influence of the surface modification of the CFs by magnetron sputtering on the mechanical and interfacial properties of CF composites was analyzed by testing the tensile and bending properties of the CFER composites. The results indicated that the surface morphology of CF can be modified by magnetron sputtering, and a nano sized carbon film was deposited on the surface of the CFs. The morphology of the carbon film on the surface of the CFs was different from that on the silicon pellet. The surface roughness of the CF increased after it was modified by magnetron sputtering. The surface wettability of the CFs may be improved by increasing the surface free energy of the fiber owing to the deposition of the carbon film. Tests of the tensile and bending properties of the CFER composites showed that the surface modification of CFs by magnetron sputtering can effectively improve the mechanical properties of the CFER composites, which not only improves the tensile strength and bending strength, but also increases the tensile modulus and bending modulus. The SEM images showed that the interfacial adhesion between the modified CF and the epoxy resin was significantly improved. The stress–strain curves showed that the failure mode of the CFER composite modified by magnetron sputtering CF surface changed, and a stress yield phenomenon was observed.