Study on the Corrosion Behavior of Nano-Coating/Aluminum Alloy Systems in Alternating Wet and Dry Environments
Objective To evaluate the corrosion behavior of nano-coating/aluminum alloy system in alternating wet and dry environment.Methods:The EIS values of the nano-coating/aluminum alloy samples were tested under the environment of alternating dry and wet corrosion,and the EIS characteristics of the samples in the early,middle and later stages of corrosion were analyzed.The electrode impedance model of the coating system under alternating dry and wet environment was established to obtain the EIS parameter characteristics of the coating electrode and the changes of water absorption process.Results The failure process of the coating failure system in the alternating dry and wet environment is as follows:in the early stage of corrosion,the Bode diagram of the coating is shown as a straight line,and there is no electrochemical reaction on the surface of the coating at this time,and the coating has reversible properties;In the middle stage of corrosion,two arc characteristics appeared in the impedance spectrum,and the electrochemical corrosion behavior of the coating surface had begun,and the coating was gradually damaged.In the later stage of corrosion,under the action of corrosion products,the coating bubbles and other phenomena,and the coating has completely lost its protective function.Conclusion The capacitance value of the silane epoxy hybrid nanocoating/2024 aluminum alloy system is positively correlated with the acceleration time in the alternating wet and dry environment,which satisfies Fick's first law,and the diffusion coefficient D of water in the silane epoxy hybrid nanocoating is 1.725 3×10-9 cm2·s-1.
nano-coatingalternating dry and wet environmentEIS mapdiffusion coefficien
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