Modern experimental approaches to study the self-healing ability of conversion coatings on galvanized steel

• E.A. Zheludkova, A.A. Abrashov, V.A. Kovalyova, N.S. Grigoryan, I.A. Kuznetsov and T.A. Vagramyan

Mendeleev University of Chemical Technology of Russia, 9 Miusskaya Sq., 125047 Moscow, Russia

Abstract: A comprehensive procedure for studying the self-healing ability of conversion coatings was developed for the first time. The procedure is based on the detection of zinc corrosion products within defects with different predefined and reproducible geometry on a studied surface after accelerated self-healing. The criteria used to evaluate the self-healing ability of the coatings included the appearance of defects in SEM images, changes in their geometric dimensions, and changes in the cerium content within the damaged areas relative to the initial coating composition. It was found that cerium- and cerium-lanthanum-containing coatings, like chromate coatings, possess self-healing ability. It was discovered for the first time that, during the self-healing process, the fraction of Ce³⁺ compounds increases within the damaged areas of the newly formed cerium-lanthanum-containing coatings. The results of this work can be used for the corrosion protection of zinc-galvanized products as an alternative to highly toxic chromating technologies. These conversion coatings may be used as standalone protective coatings. They may find application in the automotive, instrument-making, aerospace, shipbuilding, chemical, petrochemical, and other industrial sectors.

Keywords: corrosion protection, conversion coatings, self-healing, surface treatment, chromate-free passivation, rare-earth metals

Int. J. Corros. Scale Inhib., 2026, 15, no. 3, 454-472
doi: 10.17675/2305-6894-2026-15-3-20

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