New Atmospheric Corrosion Inhibitor of D16 Aluminum Alloy

—A mixed corrosion inhibitor (CI), which is an equimolar composition of sodium oleyl sarcosinate (SOS) and sodium flufenaminate (SFF), to protect the D16 aluminum alloy from atmospheric corrosion has been studied here. Polarization measurements used to assess the efficiency of preliminary passivation of the alloy with solutions of SOS, SFF, and their composition showed significant advantages of mixed CI. The features of CI adsorption on the surface of the D16 alloy are studied by XPS. It has been established that the adsorption of SOS and SFF separately results in the formation of monolayer coatings firmly bound to the alloy surface with a thickness of no more than 2.6–3.2 nm. When these CIs are adsorbed together, the layer thickness reaches 12–20 nm. This layer contains significant amounts of Al 3+ ions (~20%) related to compounds with SFF and SOS, as well as aluminum hydroxides. A possible mechanism for the formation of such a protective layer is proposed. The results of corrosion tests in a humid atmosphere with daily condensation of moisture on D16 alloy samples confirm the high protective ability of the mixed CI.