Evolution of electrochemical impedance spectra of adaptive polymer anticorrosive coatings modified with carbon nanotubes exposed to corrosive environment

• V.А. Golovin, S.А. Dobriyan and V.E. Kasatkin

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

Abstract: It is shown that modification of an adaptive epoxy coating material by carbon nanotubes (CNTs) can lead to a significant change in the structural and electro-physical properties of coatings, which manifests itself in a significant increase in thixotropic properties (by a factor of 5–13) and a sharp decrease (by 2–3 orders of magnitude) in the volume electric resistivity of the coating film. These properties determine the qualitative and quantitative changes in the electrochemical characteristics of coatings during exposure to aggressive media. It is shown that the evolution of the electrochemical properties of adaptive polymer coatings modified by CNT during exposure in an aggressive environment is primarily manifested in characteristic changes in the electrochemical impedance spectra. The changes are recorded from the initial moment of exposure in an aggressive environment and manifest themselves in the appearance of a new relaxation process and a significant change in the electrochemical impedance spectra during prolonged exposure of coatings. When modified by introduction of CNTs into the adaptive coating, a structuring effect is observed, which manifests itself in two ways: on the one hand, in the inhibition of the adaptive ability of the coating film at the initial stage of exposure on both Pt and St3 substrates, and on the other hand, it is expressed in the stabilization of the characteristics of the electrochemical impedance of modified coatings on carbon steel (St3) during prolonged exposure, even in hot chloride solutions. This is manifested in a slower drop in the absolute values of the impedance and a simultaneous increase in the phase angle.

Int. J. Corros. Scale Inhib., 2023, 12, no. 4, 1521-1534
doi: 10.17675/2305-6894-2023-12-4-7

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