Polymer coatings’ long-term adaptation and self-healing effects in corrosive media

• V.A. Golovin, S.A. Dobriyan and A.K. Buryak

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

Abstract: Adaptation and self-healing effects in composite multilayered coatings (CMCs) with active additives are estimated in 3% NaCl solution at 60°C. It is shown that coatings with a high long-term protective efficiency can be created as two-layer composite coatings with two adaptation and self-healing mechanisms: for the primer, formation of solid-phase blocking products and, for the upper coating layer, additional polymerization of the active oligomer. The enhancement of the insulating properties manifests itself as an increase in the absolute impedance value |Z| (at the characteristic frequency of the high-frequency (HF) process), an increase in |Z| in the low-frequency (LF) range of the process, and an increase (by a factor of 6.7 on platinum and 1.5 on steel) of the active resistance R1 in the region of HF charge transfer. It is found that the potential of the protected metal under the CMC increases during exposition in NaCl and passes to the positive range, and this effect is observed both on steel and platinum substrates. The ennoblement of the potential of the steel substrate under the CMC is qualitatively similar to the process observed on the platinum substrate, so it can be interpreted as a kind of steel substrate passivation. Steel substrate potential under the CMC remains positive on long exposure times (up to 500 days at 60°C).

Keywords: polymer coatings, multilayered coatings, composite coatings (CMC), corrosive media, adaptation, self-healing, electrochemical impedance spectroscopy, EIS, potential

Int. J. Corros. Scale Inhib., 2022, 11, no. 3, 1172-1190
doi: 10.17675/2305-6894-2022-11-3-16

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