Effect of anodizing surface morphology on the adhesion performance of 6061 aluminum alloy

Abstract An experimental investigation on the phosphoric acid anodizing process of 6061 aluminum alloy has been carried out to enhance the adhesive bonding strength of 6061 aluminum alloy and the carbon fiber reinforced thermo-plastic. The phosphoric acid anodizing parameters of 6061 aluminum alloy were optimized by an orthogonal experiment design, and substrates with different surface morphologies were obtained. The surface free energies, surface roughness, and joint failure morphologies of samples with specific surface morphology were examined and analyzed to comprehensively evaluate the effect of surface morphology on the bonding performance of joints in high-temperature applications. The results indicate that under appropriate conditions, phosphoric acid anodization can change the fracture mode of the joint between the 6061 aluminum alloy and thermoplastic polyetheretherketone adhesive, as well as improve the performance of the joint. The appropriate number of circular structure pits on the surface of the aluminum alloy is key to improving the shear strength of the joint.