Effects of adaptation and self-healing of protective polymer coatings in corrosive media

• V.A. Golovin and S.A. Dobriyan

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

Abstract: The existence of the adaptation effect and enhancement of insulating and protective properties of protective polymer coatings in aggressive NaCl solution was studied. Two types of composite multilayer coatings (composite ML-Ct) were explored that contained the same commercial-quality Zn-rich protective primer and the top layers of inert epoxy enamel or a chemically resistant epoxy coating with reactive phenol-furan (RPF) additives. The coatings were applied onto inert (platinum, Pt) or corroding (steel, St3) substrates. A combination of a primer layer and an upper layer with specific active additives (ML-Ct М-01// model epoxy-RPF) in the ML-Ct is an optimal way since it ensures an increase in both total (|Z|) and active (R_act) resistance of the composite coating. It was found that the effect is rather long-lasting even for model thin-layer systems and may exceed hundreds of days in accelerated tests in 3% NaCl at an elevated temperature (60°C). The forecast for the service life of industrial-thickness coatings under standard conditions of use is 10 years or more. The results obtained demonstrate that this type of composite ML-Ct with active additives can be used as a basis for the development of a new class of polymer coatings with the effect of growing protective capacity in corrosive media (adaptive coating) and self-healing coatings.

Keywords: corrosion protection, polymer coatings, underfilm corrosion, electrochemical impedance spectroscopy, equivalent circuit

Int. J. Corros. Scale Inhib., 2022, 11, no. 2, 705-726
doi: 10.17675/2305-6894-2022-11-2-18

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