Combined method of zinc protection in aqueous solutions with superhydrophobic coatings and corrosion inhibitors

• G.V. Redkina and Yu.I. Kuznetsov

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

Abstract: A new combined method of anticorrosion zinc protection in NaCl solutions, which involves the superhydrophobization of its surface and addition of small amounts (1.0 mM) of corrosion inhibitors (CIs) to the corrosive media was suggested. According to corrosion tests and contact angle measurements (Θ_c), the CIs studied, differing in chemical nature and mechanism of action, are arranged in the following sequence according to their efficiency in zinc protection in 1.0 mM NaCl using the combined method: zinc aminotris(methylenephosphonate) (ATPZn) > CeCl₃ > Ce(NO₃)₃ > cerium aminotris(methylenephosphonate) (ATPСе) > Na₂B₄O₇ > sodium dodecylphosphonate > Zn(H₂PO₄)₂ = NaNO₂ > sodium meta-nitrobenzoate. According to electrochemical tests, the mechanisms of inhibitive action of CIs that have shown high efficiency in protection of zinc coated with a SHP alkylphosphonate film, namely CeCl₃, Ce(NO₃)₃ and ATPZn, differ. At the concentration studied, CeCl₃ is a cathodic inhibitor, Ce(NO₃)₃ is an anodic inhibitor, while ATPZn acts as mixed type inhibitor, which determines its greatest efficiency. The suggested combined method of zinc protection was proven to be highly effective. Thus, the addition of 1.0 mM ATPZn to 1.0 mM NaCl solution prevents the degradation of the SHP film on zinc and increases its corrosion resistance significantly, ensuring the absence of visible corrosion damage and Θ_c>150°C for 72 days.

Keywords: zinc, superhydrophobicity, corrosion inhibitor, complexonates, alkyl phosphonates, laser treatment

Int. J. Corros. Scale Inhib., 2023, 12, no. 4, 1863-1882
doi: 10.17675/2305-6894-2023-12-4-24

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