Constructing quasi-Z-directional epoxy-pins on aluminum alloy surface via highly controllable laser engraving for stronger adhesive bonding with carbon fiber composite

This study designed laser engraving, atmospheric pressure plasma spraying and resin pre-coating (RPC) on aluminum alloy surface to construct quasi-Z-directional “epoxy-pins” for improving bonding strength with carbon fiber reinforce polymer (CFRP). The laser engraving treatment was used to create pitted structure on the aluminum alloy surface, higher wettability was acquired and greater vertical spaces were formed to impregnate epoxy resin for stronger mechanical interlocking. Atmospheric pressure plasma spraying was then utilized to remove surface contaminants of aluminum alloy surface and increase the quantity of adsorbed polar functional groups. RPC technique was further adopted to guide high-viscosity epoxy resin into pits to minimize defects between the resin and the substrate and reinforce the mechanical interlocking. The bonding strength of the specimen with the combined treatments of L0.08-1 yielded up to 130.5% increment than the base in bonding strength. The failure modes of composites were changed from adhesive failure of aluminum alloy surface to delamination-dominated failure of laminated CFRP composites. Simple and effective combined treatment method is expected to gain application in the development of high performance of heterogeneous material bonding.