Experimental study of CFRP laser surface modification and bonding characteristics of CFRP/Al6061 heterogeneous joints

With the increasing demand of modern aerospace lightweight, the reliable connection between CFRP and aluminum alloy becomes a difficulty. In this paper, the effect of laser modification on the bonding strength of CFRP surface was studied. Different patterns of laser treatment were used to improve the bonding strength of CFRP surface. SEM and EDS were used to characterize the surface morphology and element types and contents of CFRP after laser treatment. It was found that the bond strength was directly affected by the exposed continuity of carbon fiber and the residual resin. The bond strength of annular pattern with large diameter and large spacing was the highest, and the main failure mode was cohesive failure . With the increase of scanning times, the bond strength increased first and then decreased, and the capillary effect of the carbon fiber and the air pressure in the micro groove play a leading role. In a word, the laser patterning pretreatment on the surface of CFRP is beneficial to improve the bonding strength of heterogeneous joints, and the maximum bonding strength can reach 28.58mpa.