Laser surface treatment of CFRP composites for a better adhesive bonding owing to the mechanical interlocking mechanism

Adhesion can be greatly improved by the correct surface preparation techniques. One of the most common and useful technique is specific surface structuring which leads to mechanical interlocking and greater adhesion. This work describes the effect of laser-induced line pattern surface structuring on the mechanical interlocking mechanism and so on the adhesive bonding of carbon fiber reinforced polymer (CFRP) composites. Surface patterns with different laser scribes were obtained by CO2 laser treatment. The effect of the number of a laser shot, the scribe depth, the number of the scribe and the angle between the direction of the laser scribes and mechanical test direction on the adhesive bonding strength of CFRP/CFRP joints was investigated by performing the single lap shear tests according to the ASTM D5868-01. After destructive tests, damaged surfaces were analyzed for determining the failure mechanisms. Mechanical tests showed that laser scribe characteristics especially the number of laser shot and the number of scribes have significant effects on the mechanical interlocking mechanism and so on the adhesion bonding strength. It is suggested that in order to improve the adhesion strength of CFRP/CFRP joints, mechanical interlocking mechanism shall be obtained by optimized laser scribe patterns. POLYM. COMPOS., 40:3611-3622, 2019. (c) 2019 Society of Plastics Engineers