CNT toughened aluminium and CFRP interface for strong adhesive bonding

Abstract This study presents a simple technique for strengthening the adhesive-bond strength between aluminium (Al) substrate and carbon fibre reinforced polymer (CFRP) utilising resin pre-coating (RPC) with carbon nanotubes (CNTs). The CNT-containing RPC solution with 90 ​wt% acetone and 10 ​wt% resin (without hardener) was applied onto Al substrates, where micro-/nano-vertical channels had been created by chemical or mechanical surface treatments to accommodate CNTs. RPC was able to fill all micro-/nano-cavities over the Al substrate surface, then CNTs were pulled into those vertical micro-channels by the capillary action generated from acetone evaporation. Normal epoxy adhesive (resin ​+ ​hardener) was applied after the CNT-containing RPC treatment. CNTs bridging across the interface between the adhesive joint and Al substrate and sealing of micro-/nano-cavities by RPC effectively enhanced the interfacial shear bond strength between the Al substrate and CFRP by 30–100% depending on the Al substrate surface profiles. Al substrates with two different chemical treatments were compared in this study for the effectiveness of CNT interfacial reinforcement. Results from a steel substrate after sandblasting were also included for comparison.