Features of passivation of galvanized steel with alkylphosphonic acids and octyltriethoxysilane

• A.S. Rozhkov, G.V. Redkina and A.S. Sergienko

A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninsky pr. 31, 119071 Moscow, Russian Federation

Abstract: In the present work, the influence of the solvent nature in alkylphosphonic acid (C_nPs) solutions, the structure of their molecules, namely the hydrocarbon radical length, on the protective and hydrophobic properties of thin films formed on the galvanized steel surface with different morphologies, including those formed by sequential passivation with octyltriethoxysilane (OTES), was studied. It was found that passivation of galvanized steel in ethanol solutions of dodecylphosphonic acid and OTES is more effective than in aqueous solutions of sodium dodecylphosphonate, both when applied alone and in layer-by-layer passivation together with OTES. The inhibiting ability of C_nPs with n_C=12 and 16 towards galvanized steel enhances with the increase of the hydrocarbon radical length. This regularity is observed both when using C₁₂P and C₁₆P separately and together with OTES. Pre-modification of galvanized steel surface by laser enhances protective and hydrophobic properties of thin films formed in C_nPs and OTES solutions. Layer-by-layer treatment of galvanized steel in ethanol solutions of C₁₆P and OTES with a laser surface pre-treatment is most effective for protection of galvanized steel from corrosion in various corrosive atmospheres, namely high humidity with condensation of moisture on the metal surface, in salt spray and in industrial-urban atmosphere.

Keywords: galvanized steel, corrosion inhibitor, alkylphosphonic acid, trialkoxysilane, superhydrophobization, laser treatment

Int. J. Corros. Scale Inhib., 2024, 13, no. 4, 2454-2472
doi: 10.17675/2305-6894-2024-13-4-31

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