Constructing quasi-vertical carbon nanotubes fiber bridging on aluminum alloy with micro-channels to improve adhesive bonding with carbon fiber reinforced polymer composites

The poor wettability and compatibility, and weak mechanical interaction of bonding interface are main concerns for adhesive bonding of aluminum (Al) alloy and carbon fiber reinforced polymer (CFRP) composite, limiting its high strength developing and industrialization. In this study, the united treatments of anodizing, chemical vapor deposition (CVD) and resin pre-coating (RPC) were adopted to construct the quasi-vertically distributed carbon nanotube (CNT) fiber bridging for reinforcing the adhesive bonding joints. The results exhibited that better surface properties including morphology, roughness and wettability were obtained after anodizing. CNTs could be in-situ grown via the novel CVD method in the channels or micro-cavities formed by anodizing treatment. Acetone-diluted epoxy resin solution enabled to flow into the root of micro-cavities or the gap of growing CNT fibers to reduce potential void defects. Single lap shear test results indicated that Al-CFRP composites treated by anodizing, CVD and RPC performed up to 136.1 % increment in strength compared to the base. While the original debonding failure on Al alloy surface was changed into the complete delamination failure of CFRP composites, verifying the stronger bonding interface and strength. Thus, the novel united treatments were effective and might be an alternative solution in developing high-performance Al-CFRP composites.