Experimental study on hydrophobic properties and corrosivity of laser cleaned 7075 aluminum alloy anodized film surface

In this paper, nanosecond pulse laser was used to clean the anodic oxide film on the 7075 aluminum alloy surface. The effects of different laser energy densities (3.11–4.44 J/cm2) on the 7075 aluminum alloy surface morphology, composition, roughness, microhardness and contact angle were studied. The hydrophobicity of aluminum alloy surface after laser cleaning was studied, and the effect of laser cleaning on the corrosion resistance of aluminum alloy surface was analyzed. The results show that when the laser energy density reaches 4.44 J/cm2, the surface oxygen content of 7075 aluminum alloy is 0.37 % and the surface roughness is 0.395 μm. Laser cleaning can remove the anodic oxide film on the surface of 7075 aluminum alloy. The new surface formed after laser cleaning is acceptable without damage. Compared with mechanical removal method, under the specific laser energy density (4.44 J/cm2), the microhardness of the surface is slightly improved, while the hydrophobicity is significantly improved, which provides the feasibility of anti-corrosion for regular use after laser cleaning. This work provides basic research and practical guidance for laser cleaning of anodic oxide film on 7075 aluminum alloy surface.