Pulse laser cleaning of aircraft aluminum alloy skin composite paint layer: Electrochemical corrosion behavior

To investigate the impact of laser cleaning on the corrosion resistance of aircraft skin surfaces, a pulsed laser was utilized to remove the composite paint layer from the aluminum alloy skin surface. The effects of varying energy densities on the surface morphology, composition, and electrochemical corrosion resistance of 2024 aluminum alloy were examined. The investigation focused on elucidating the factors contributing to the enhancement of corrosion resistance and unraveling the underlying corrosion mechanism. The results revealed that at a laser energy density of 5.87 J/cm 2 , the functional groups on the sample surface were no longer detectable, resulting in decrease in roughness Sa to 0.363 μm. Additionally, the content of titanium (Ti) element specific to the paint layer decreased to 0.15 %, indicating substantial removal of most of the surface paint layer. Meanwhile, at this energy density for laser cleaning, the corrosion rate is reduced to 0.15 mm/year, representing a decrease of only 26.32 % compared to the corrosion rate observed in mechanically polished samples. By employing impedance spectroscopy in conjunction with corrosion morphology analysis, it was observed that the oxide film significantly enhances the overall impedance of the sample. The corrosion resistance is directly influenced by the integrity of the surface anodic oxide film. Under the combined action of stress, when exposed to a sodium chloride solution, the sample exhibited ehanced corrosion resistance as evidenced by only slight cracks formation in the corrosion solution at a laser energy density of 5.87 J/cm 2 .