Structure and properties of protective films of oleic acid formed by immersion and chamber treatment on chemically oxidized magnesium

Applying a conversion coating combined with subsequent application of an inhibitor film is an efficient and popular method to increase the corrosion resistance of metal products.In this work, a set of physical, electrochemical and corrosion methods was used to compare the structure and protective properties of oleic acid films formed on an oxidized surface of Mg90 magnesium from alcoholic solutions and from hot acid vapors.It was shown that both methods resulted in the formation of thin (up to 100 nm) layers on the surface, which increased the protective properties of the oxide coating.The maximum protective effect was shown by the film obtained by one-hour treatment in an alcoholic solution containing 8 mM of the acid.Voltammetric studies showed that this film suppressed anodic dissolution.Using electrochemical impedance spectroscopy, the protective effect was shown to be provided by a mixed blocking-activation mechanism.