Optimizing adhesive bonding between CFRP and Al alloy substrate through resin pre-coating by filling micro-cavities from sandblasting

Abstract Strong adhesive bonding between carbon fibre reinforced polymer (CFRP) and aluminium (Al) alloy substrates is essential for structural integrity of modern aircrafts. This study reports a simple and effective method to increase the adhesion interface strength between CFRP and Al alloy substrates by means of a combined sandblasting and resin pre-coating (RPC) process. The RPC technique is used to maximize the full potential of surface abrasion from sandblasting by sealing all micro-cavities and wetting the entire surface and sub-surface openings over the Al substrate and CFRP. The RPC solution consisting of around 90 wt% of acetone and 10 wt% of resin (without hardener) takes resin into the surface micro-openings and effectively increases the wettability of bond surfaces. Based on single lap shear tests, over 170.2% of improvement in the shear strength has been achieved by the combined sandblasting and RPC method in compared with the adhesive joints without any surface treatment. The surface roughness, contact angle measurements and Scanning Electron Microscope (SEM) observations are conducted to investigate the wettability and microstructural details, confirming the effectiveness of the RPC technique.