Effect of Laser Deoxidation on Adhesive‐Bonded Aluminum in an Oxygen‐Free Atmosphere

This study investigates how laser ablation in an oxygen‐free atmosphere affects the surface morphology of aluminum alloys and their adhesive strength when using epoxy adhesive. The focus is on optimizing the laser parameters to improve adhesive strength considering both reoxidized and oxide‐free surfaces. Results show that laser parameters and processing atmosphere significantly influence surface morphology and chemistry, which significantly influence the adhesive strength. The highest bond strength is achieved with 90% overlap, 300 µJ energy input, and an oxide‐free surface. Samples processed in air show predominantly adhesive fractures, whereas oxygen‐free processing leads to more cohesive fractures, especially with higher overlap and energy input. Increased overlap and energy input lead to an increase in bubble formation within the adhesive. These bubbles are mostly concentrated in the center rather than at the interface between metal and adhesive. Metallographic cross‐sections and micro‐computed tomography (micro‐CT) images confirm good surface wetting, indicating that wettability is not a limiting factor. However, the presence of bubbles may reduce joint strength by acting as predetermined breaking points. The study concludes that laser ablation affects the surface roughness and oxidation state of aluminum, thereby improving adhesive strength with epoxy adhesive. Degassing the adhesive joint may enable further improvements in strength.