Institute of Chemistry of the Far Eastern Branch of the Russian Academy of Sciences, Vladivostok, Russia

A. S. Gnedenkov, Principal Researcher, Head of the Laboratory, Professor of the Russian Academy of Sciences, Doctor of Chemical Sciences, e-mail: asg17@mail.com
S. L. Sinebryukhov, Deputy Director, Corresponding Member of the Russian Academy of Sciences, Doctor of Chemical Sciences, Associate Professor, e-mail: sls@ich.dvo.ru
V. S. Marchenko, Junior Research Assistant, e-mail: filonina.vs@gmail.com
S. V. Gnedenkov, Director, Corresponding Member of the Russian Academy of Sciences, Doctor of Chemical Sciences, Professor, e-mail: svg21@hotmail.com

The method of formation of the hybrid coating with a self-healing function on the surface of MA8 alloy was developed using the plasma electrolytic oxidation method, which provides the obtaining of a ceramic-like base suitable for subsequent modification of the protective layer with halloysite nanotubes (HNTs) used as nanocontainers for the inhibitor. The method of impregnating HNTs with a benzotriazole (BTA) corrosion inhibitor and injecting them into a matrix of a bioresorbable polymer material – polycaprolactone (PCL) was proposed. Hybrid coatings containing HNTs loaded with BTA in the PCL polymer matrix, as well as a composite coating containing polycaprolactone and HNTs without an inhibitor were formed and studied. The morphology, elemental and chemical composition of the formed protective layers were established using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-Ray diffraction analysis and X-ray photoelectron spectroscopy. The level of anticorrosive protection of the coatings was determined using electrochemical impedance spectroscopy and potentiodynamic polarization during sample exposure to Hanks’ balanced salt solution. It was found that the best protective properties were possessed by anticorrosion coating containing HNTs with benzotriazole. The selfhealing mechanism of samples with a hybrid layer was established, consisting in the formation of a poorly soluble Mg(BTA–H)2 complex in the defect area. Such a passivation layer prevents the penetration of aggressive chloride ions to the Mg alloy substrate and ensures the formation of crystalline corrosion products that protect the material against degradation. The multifunctional hybrid protective coating formed on the surface of the biodegradable magnesium alloy has improved anticorrosion properties and helps to expand the scope of practical application of the biodegradable material.

The formation of a smart coating and the determination of a corrosion mechanism of the material were carried out with the support of RSF (project No. 24-73-10008). The study of the chemical composition and electrochemical properties was carried out with the support of RSF (project No. 20-13-00130). X-Ray diffraction analysis data were obtained within the framework of the state assignment of the Ministry of Science and Higher Education of the Russian Federation (project no. FWFN(0205)–2025–0001).

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