Long-Term Atmospheric Aging and Corrosion of Epoxy Primer-Coated Aluminum Alloy in Coastal Environments

Aircraft are subjected to extreme weather conditions in coastal areas. This study reports long-term atmospheric exposure tests carried out on an epoxy primer-coated aluminum alloy in a coastal environment for 7, 12, and 20 years. The micromorphology and characteristics of the section and surface, the products of corrosion, electrochemical impedance, and molecular structure of the coated specimens were examined through a spectrophotometer, scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectrometer (XPS). The results showed that the angles of contact of the specimens with different numbers of years of atmospheric exposure satisfied the normal distribution. Their fractal dimensions increased with an increase in the duration of exposure. Intergranular corrosion and exfoliation corrosion appeared in the specimens after 20 years, where the product of corrosion was Al(OH)(3). The impedances and thermal properties of the epoxy coatings were influenced by the synergistic effects of aging and post-curing. The impedances of the coatings decreased greatly after long-term atmospheric exposure. After 20 years of corrosion, the specimen showed the characteristics of the substrate being corroded. The mechanism of corrosion and the electrochemical equivalent circuit were also analyzed.

Automated summary

Long-term atmospheric exposure tests on epoxy primer-coated aluminum alloy in a coastal environment showed that different durations of exposure resulted in a normal distribution of contact angles, with Al(OH)(3) as the corrosion product after 20 years, indicating intergranular and exfoliation corrosion. The impedances of the coatings decreased significantly after long-term exposure, with the substrate showing signs of corrosion after 20 years. The study also analyzed the corrosion mechanism and electrochemical equivalent circuit.