Effect of Scanning Speed with UV Laser Cleaning on Adhesive Bonding Tensile Properties of CFRP

The surfaces of the carbon fiber resin matrix reinforced polymer (CFRP) are completely cleaned and partially cleaned by controlling the ultraviolet laser (UV) scanning speed. Residual resin and surface energy of laser cleaning samples are analyzed and correlated to the adhesive bonding tensile properties. The results show that the main damage form of CFRP bonding joints obtained by UV laser complete cleaning and partial cleaning are mixed failure, in which the interface failure and cohesion damage play an important role in the tensile properties of the two kinds of joints, respectively. The surface of the samples after UV laser partial cleaning has been proved to have obvious infrared absorption peaks. Residual resin on the surface of partial cleaning samples is beneficial to improve the tensile properties of bonded samples. The CFRP surface energy by UV laser partial cleaning is 83.35 mJ/m², which is far higher than that of the original surface. Nevertheless, the CFRP surface energy after UV laser complete cleaning is 56.67 mJ/m², which is lower than that of UV laser partial cleaning. To a certain extent, the magnitude of the surface energy reflects the bonding property of CFRP. Therefore, the strength of the CFRP adhesive joint after partial cleaning is stronger than that of CFRP joints after complete cleaning.