Electrochemical properties and processes of self-healing of multilayer metal-filled coatings during exposure in a 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: As part of the development of a concept for creating “smart” adaptive anticorrosive polymer coatings, the kinetics of electrochemical properties of thin- and thick-layer multilayer Zn-filled coatings at various temperatures from 23 to 60°C during prolonged exposure for up to 150 days in 3% NaCl has been studied. It has been shown that at low temperatures and hence at low corrosion rates of the zinc (Zn) filler, it is advisable to increase the thickness of highly filled composite coatings with active solid-phase additives in order to reduce porosity and create conditions for a restorative increase of the electrical insulating properties of the coating. The self-healing process in multilayer coatings can be activated with an increase in temperature. In fact, already at 40°C, the impedance modulus begins to grow in the entire frequency range. At the same time, an increase in the ohmic component in the high-frequency (HF) region is recorded, with a simultaneous drop in capacitance and an increase in the phase angle modulus up to 86°, which indicates an increase in the hydrophobicity of the coating material. In parallel, activation of protector properties is observed. The results obtained show that optimization of the coating design, in particular multilayering, combined with acceleration of coating’s internal diffusion and corrosion processes, make it possible to give the coating “smart” properties by implementing adaptive impedance modulus growth and blocking defects with a corroding metal dispersed filler while significantly extending the period of anticorrosion protection.

Keywords: electrochemical impedance spectroscopy, EIS, polymer coatings, “smart” adaptive coatings, self-healing coatings

Int. J. Corros. Scale Inhib., 2024, 13, no. 2, 1337-1354
doi: 10.17675/2305-6894-2024-13-2-37

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