Effect of Plasma Surface Treatment on Bonding Properties and Surface Properties of CFRP

To improve the surface wettability and surface activity of Carbon fiber reinforced plastics (CFRP) and enhance its bonding strength, the surface treatment of CFRP is carried out with rotary jet air plasma treatment equipment. The influence of plasma surface treatment distance and treatment speed on the bonding performance of CFRP is investigated by tensile test, and contact angle measuring instrument (CA), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and other testing techniques are used. The effects of plasma treatment on surface wettability, surface morphology and surface chemical composition of CFRP are investigated. Results show that the bonding strength of CFRP surface increases gradually after plasma treatment. The maximum bonding strength is obtained when the treatment distance h is 10 mm and the treatment speed v is 2 mm / s. The joint failure mode changes from interface failure to mixed failure mode. With the decrease of plasma treatment distance and speed, the surface water contact angle decreases, the surface free energy and polar component increase, and the surface wettability and adsorption performance improve. After plasma treatment, the surface area of CFRP is increased by micron-level gullies. However, when the treatment distance is relatively close, some surface resins are damaged due to plasma thermal response, which is not conducive to the further improvement of bonding properties. After the composite substrate interacts with the active particles in the plasma, the oxygen-containing groups on the surface increase, and C-O / C-O, C=O/O-C=O and other relatively active oxygen-containing groups are produced, which is conducive to the formation of a strong chemical bond between the composite and the adhesive. Therefore, plasma treatment can significantly improve the surface wettability, surface activity and bonding properties of composites.