Electrochemical Corrosion Behaviors of Silicone-epoxy Hybrid Coatings/LY12 Al-alloy in Seawater

The corrosion behavior of LY12 aluminum alloy based silicone-epoxy hybrid coating in seawater was investigated by using electrochemical impedance spectroscopy (EIS) and the impedance model which adapted coating/metal systems at different phase of immersion was proposed. The absorption and the diffusion coefficient of moisture in the failure process were studied by the method of capacitance analysis. The results showed that in the sea water environment, silicone epoxy coating surface can be covered with a layer of dense corrosion products, which can prevent the corrosion medium to penetrate into the internal coating effectively. Absorbent coating process can be divided into two phases: the linear increase phase and the increased and stabilized phase. Finally, the diffusion coefficient D of water of the silicon-epoxy hybrid coatings in seawater was calculated, D=0.605 22×10-9 cm2·s-1.