Study on corrosion behavior of two aluminum coatings in marine environment

摘要

The corrosion behavior of two aluminum coatings in simulated marine environment was studied, including ion vapor deposition aluminum (IVD Al) and ionic-liquid based electroplating aluminum (ILEp Al). Besides compact coatings, cross-scratched ones of IVD Al and ILEp Al were alternatively immersed into artificial seawater to simulate the marine environment. This study investigated the corrosion behavior of the two Al coatings in a 1000h immersion. The morphology of the coatings was observed by using optical microscope (OM) and scanning electron microscope (SEM). The atomic force microscopy (AFM) was applied to measure the surface roughness of the coatings. To quantitatively study the evolution of coating structure, the electrochemical impedance spectrum (EIS) was carried out to examine the coatings at different time during the 1000h alternative immersion test in artificial seawater. The data of EIS of the coatings was fitted by using equivalent circuit, to provide elemental information, such as capacitance and resistance of the coatings. The scanning Kelvin probe (SKP) was used to map the electrical potential of the scratch area of the coatings. The results showed that the two aluminum coatings experienced corrosion to a certain extent after a two-year exposure. However, both coatings exhibited good protection to the steel substrate.