Electrochemical properties of Zn-rich primers and composite coatings on various metal substrates

• V.A. Golovin, S.A. Dobriyan, V.A. Shchelkov and A.I. Shcherbakov

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

Abstract: The peculiarities of formation of the potentials of metal substrates (Steel-3, Zn, and Pt) with Zn-rich primers deposited both individually and as a component of composite coatings with an upper insulating layer were studied. It was shown that upon long-term exposure to a 3% NaCl solution, the potentials of the composite coatings deposited to all the substrates were more positive than those established if primers alone were used. With an increase in exposure time, the potential of the substrate under a coating grew both in the case of solvent- and water-borne composite coatings. Temperature is an essential factor determining both the value and kinetics of the potential of substrates under composite coatings. At low temperatures, the corrosion protection properties of the composite coatings were poorly expressed, as distinct from that when only the primer was used. At low temperatures, the composite coatings are mostly exploited at positive potentials of the steel substrate. An increase in temperature radically activated the corrosion protection properties of the composite coatings, despite a growth in the impedance of the primers at temperatures close to +60°C. The potential of protective additives both for a primer itself and Zn-rich primer as a component of the composite coating system was estimated.

Keywords: corrosion protection, polymer coatings, Zn-rich primers, EIS

Int. J. Corros. Scale Inhib., 2020, 9, no. 1, 56-73 PDF (635 K)
doi: 10.17675/2305-6894-2020-9-1-4

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