Effect of solid-phase ZnO additive on the electrochemical and protective properties of Zn-filled coatings at various exposure temperatures in a 3% NaCl solution

• S.A. Dobriyan, V.A. Shchelkov and A.B. Il’in

Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31-4, Leninsky prospect, 119071 Moscow, Russia

Abstract: To develop the concept of creating coatings modified with active additives, the regularities of changes in the electrochemical properties of thin- and thick-layer multilayered Zn-filled coatings with additionally incorporated solid-phase ZnO additive was studied. The study was carried out over a wide range of operating conditions with exposure in a 3% NaCl corrosive solution at temperatures up to 60°C for periods of up to 150 days. Particular attention was paid to the analysis of the dynamics of the key electrochemical parameters, such as the total impedance modulus |Z|, phase angle δ, and potential of the steel substrate under the coating at different stages of exposure to the corrosive medium. The coating thickness, temperature of the medium, and exposure time were varied in the experiments. The addition of 8 wt.% ZnO to the coating formulation was shown to cause a pronounced stabilization of the electrochemical parameters of the thin-layer coatings during exposure to the corrosive medium at 23°C. During the initial stage of immersion, a substantial increase in the total impedance modulus |Z| was observed, but the |Z| and δ values did not decrease substantially compared with those of the unmodified coating. This effect was also observed not only at lower temperatures but also at elevated temperatures up to 60°C. This is of particular practical importance, since it indicates the resistance of the modified coatings to temperature fluctuations under real operating conditions. The stabilization of the electrochemical characteristics was accompanied by an extension of the period of sacrificial protection, allowing the coating to protect the steel substrate from corrosion for a longer time. These results open up new opportunities for the targeted development of multifunctional protective coatings with tunable electrochemical properties.

Keywords: electrochemical impedance, polymer coatings, Zn-filled composites, solid-phase additives, adaptive coatings

Int. J. Corros. Scale Inhib., 2026, 15, no. 3, 351-367
doi: 10.17675/2305-6894-2026-15-3-15

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