Femtosecond Laser Surface Treatment of Aerospace High Modulus CFRP Composites and Its Effect on Surface Wettability

Carbon fiber reinforced polymer (CFRP) is widely used in aerospace, transportation and other fields due to its excellent material properties. In order to improve the adhesive bond strength of CFRP composites, surface treatment is particularly important. In this study, femtosecond laser was used to treat the surface of aerospace high modulus CFRP composites, and the changes of resin removal and micro/nano structure of carbon fiber with laser fluence were investigated. It was found that the improvement of wettability was more favorable under the condition of removing the ablated resin and forming the complete micro/nano structure on the surface of carbon fiber. Through optimization, changing the laser fluence used in surface treatment, the water contact angle of the treated surface was reduced from 111.9° to 7.5°, greatly increasing the hydrophilicity of the surface, significantly enhancing the ductility of the surface liquid, which is expected to promote the flow and penetration of the adhesive on the surface, and further enhance the bond strength.