Study on the Influence of Aluminum Alloy Surface Roughness on Paint Adhesion

Environmental tolerance assessment standards for aviation products are becoming increasingly stringent, demanding higher performance in harsh conditions. This study investigates how surface roughness and painting process affect coating adhesion on 6061 aluminum alloy with fluoropolyurethane matte enamel. Specimens with different roughness were prepared by sandblasting （glass sand, brown corundum） and magnetic grinding （polishing needles）. Vibration and coating adhesion tests show that paint adhesion is not simply positively correlated with substrate roughness. Microscopically, grooves and pits on rough surfaces act as mechanical anchors, increasing contact area between paint film and substrate, thereby enhancing bonding strength and adhesion firmness. These findings provide a theoretical and engineering basis for optimizing aluminum alloy painting processes.