Processes of adaptation and protective characteristics growth in multilayer polymer coatings modified with carbon nanotubes

• V.А. Golovin, S.А. Dobriyan and V.A. Shchelkov

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

Abstract: The electrochemical (EC) properties of multilayer adaptive coatings (AC) modified with carbon nanotubes (CNT) have been studied. Within the framework of the theory of “similar” geometric states, a methodological approach is formulated to compare the electrochemical impedance characteristics of multilayer coatings having various thicknesses. The effect of AC modification with CNT has been studied. It has been shown that CNTs have a significant effect on the EC characteristics. For the coatings under consideration, a positive value of the potential of the substrate under the coating with CNT has been found. Moreover, with increasing exposure time, further ennoblement of both protected Pt and St3 substrates has been observed. It has been shown that the impedance kinetics of multilayer AC on different substrates can be described within the framework of a combination of known equivalent circuits (EC) (Voigt, Mansfeld, Mansfeld+Voigt) corresponding to models of defect-free coating, coatings with through pores, and coatings with internal defects. It has been shown that during exposure in a corrosive environment, the evolution of the coating/substrate EC system is observed. The nature of the evolution of the EC of the same coating is different on different metal substrates. It has been found that there is no obvious correlation of the potential of substrates (corroding St3 and inert Pt) with the corrosion potentials of the corresponding metals and with their corrosion resistance on exposure to 3% NaCl. It is suggested that in the case of AC, the potential of the substrate is formed not only by the anodic process on the substrate, but also by EC processes of oxidation and structuring in the polymer base of the AC upon exposure to the medium.

Keywords: corrosion protection, adaptive coatings, carbon nanotubes, electrochemical impedance

Int. J. Corros. Scale Inhib., 2023, 12, no. 4, 1849-1862
doi: 10.17675/2305-6894-2023-12-4-23

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