Effects of laser hybrid interfacial pretreatment on enhancing the carbon fiber reinforced thermosetting composites and TC4 alloy heterogeneous joint

To enhance the carbon fiber reinforced thermosetting composites (CFRTS) and the TC4 alloy heterogeneous joint strength, an interfacial hybrid pretreatment of laser cleaning and laser plastic-covered processing was introduced. The laser cleaning applied to remove the epoxy resin on CFRTS surface and the laser plastic-covered processing was applied to produce a thermoplastic layer on the TC4 surface. The surface morphology of CFRTS after laser cleaning, the CFRTS-TC4 heterogeneous joint enhancement and failure mechanism was investigated. The result showed that the epoxy resin on CFRTS surface could be removed effectively with this laser hybrid pretreatment and the contact area between the CFRTS and TC4 alloy can be improved. Mechanical interlocks and chemical bonds were produced at the CFRTS-TC4 interface, which further enhanced the CFRTS-TC4 heterogeneous joint strength. The CFRTS-TC4 joint fracture occurred between the carbon fibers and polyamide-6 (PA6) resin inside the CFRTS, and the fracture mode is tearing of the CFRTS interlayer.