Ufa University of Science and Technology, Ufa, Russia

N. Yu. Dudareva, Associate Professor, Professor at the Department of Internal Combustion Engines, Doctor of Technical Sciences, e-mail: dudareva.nyu@ugatu.su

V. M. Sitdikov, Head of the Educational Department – Deputy Head of the Department of Aircraft, Helicopters and Aircraft Engines of the Military Training Center, e-mail: ven_80@mail.ru

Central Scientific Research Automobile and Automotive Engines Institute NAMI, Moscow, Russia
A. V. Kolomeychenko, Professor, Head of the Innovative Technology Department, Centre for Agricultural Engineering, Doctor of Technical Sciences, e-mail: a.kolomiychenko@nami.ru

Wuhan Textile University, Wuhan, China¹ ; Vladimir State University named after Alexander and Nikolay Stoletovs, Vladimir, Russia² ; National University of Science and Technology MISiS, Moscow, Russia³
V. B. Deev*, Professor of the Faculty of Mechanical Engineering and Automation¹, Chief Researcher², Professor of the Department of Metal Forming³, Doctor of Technical Sciences, Professor, e-mail: deev.vb@mail.ru

*Corresponding Author

Oxide surface layers formed by micro-arc oxidation are usually considered to be quite corrosion resistant. However, the properties of these layers are significantly influenced by process factors. This paper describes a study that looked at the relationship between the concentration of sodium metasilicate (Na₂SiO₃) in the electrolyte and the corrosion resistance of samples. All experiments were carried out with samples of a hype reutectic aluminum alloy containing Si 24–26%(wt.) (AlSi₂₆CuNiMg – M244 grade according to the Mahle standard), as the properties of oxide layers on this alloy are poorly studied. Scanning electron microscope photographs of cross sections were analyzed to determine the thickness and structure of the oxide layer. For porosity studies, images of cross sections were analyzed with the help of the ImageJ programme. The corrosion resistance of the samples was analyzed based on the mass rate of corrosion. For this, samples with an oxide layer were kept in a corrosive solution of special composition for 144 hours. Similar tests were carried out for samples without an oxide layer. It was found that the concentration of sodium metasilicate in the electrolyte has almost no effect on the electrical parameters of micro-arc oxidation, the thickness of the formed layer or its corrosion rate. Micro-arc oxidation of the surface of M244 alloy samples helps raise their corrosion resistance by about 4 times. It is assumed that the corrosion rate of the samples is associated with the presence of open pores, through cracks and pseudo-closed pores, which look closed in the SEM image but in reality are open. An increase in the amount of sodium metasilicate in the electrolyte results in a higher closed porosity of the MAO layer without changing the through porosity.
This research was carried out under a scientific research assignment given by the Ministry of Science and Higher Education of the Russian Federation; Subject: FZUN-2020-0015, assigned to the Vladimir State University.

1. Suminov I. V., Belkin P. N., Epelfeld A. V., Lyudin V. B. et al. Plasma electrolytic modification of metals and alloys surface. In 2 volumes. Vol. 2. Moscow : Tekhnosfera, 2011. 512 p.
2. Yuting D., Zhiyang L., Guofeng M. The research progress on micro-arc oxidation of aluminum alloy. IОР Conference Series: Materials Science and Engineering. 2020. Vol. 729. 012055–012059.
3. Krishtal M. M., Ivashin P. V., Polunin A. V. Micro-arc oxidation of aluminium-silicon alloys : Monograph. Togliatti : Izdatelstvo TGU, 2016. 125 p.
4. Malyshev V. N., Gantimirov B. M., Volkhin A. M., Kim S. L. Improved antifriction properties of wear-resistant MAO coatings. Chemical Physics and Mesoscopy. 2013. Vol. 15, No. 2. pp. 285–291.
5. Kolomeychenko A. V. Extending the useful life of machine parts by restoring and strengthening the working surfaces with the help of micro-arc oxidation-based combination techniques : Monograph. 2^nd edition. Orel : Izdatelstvo OrelGAU, 2013. 230 p.
6. Mi T., Jiang B., Liu Z., Fan L. Plasma formation mechanism of microarc oxidation. Electrochimica Acta. 2014. Vol. 123. pp. 369–377.
7. Kolomeichenko A. V., Kravchenko I. N. Elemental composition and microhardness of the coatings prepared on faced aluminum alloys by plasma electrolytic oxidation in a silicate–alkaline electrolyte. Russian Metallurgy (Metally). 2019. Vol. 2019, No. 13. pp. 1410–1413.
8. Dudareva N. Y., Ivashin P. V., Gallyamova R. F., Tverdokhlebov A. Y. et al. Structure and thermophysical properties of oxide layer formed by microarc oxidation on AK12D Al–Si alloy. Metal Science and Heat Treatment. 2021. Vol. 62, No. 11-12. pp. 701–708.
9. Al Bosta M. M. S., Keng-Jeng M., Hsi-Hsin C. The effect of MAO processing time on surface properties and low temperature infrared emissivity of ceramic coating on aluminium 6061 alloy. Infrared Physics & Technology. 2013. Vol. 60. pp. 323–334.
10. Curran J. A., Clyne T. W. Porosity in plasma electrolytic oxide coatings. Acta Materialia. 2006. Vol. 54, No. 7. pp. 1985–1993.
11. Dudareva N. Y., Kolomeichenko A. V., Deev V. B., Sitdikov V. M. Porosity of oxide ceramic coatings formed by micro-arc oxidation on high-silicon aluminum alloys. Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques. 2022. Vol. 16, No. 6. pp. 1308–1314.
12. Shuqi W., Ya-Ming W., Yong-Chun Z., Chen G. L. Generation, tailo ring and functional applications of micro-nano pores in microarc oxidation coating: a critical review. Surface Technology. 2021. Vol. 50, No. 6. pp. 1–22.
13. Markov M. A., Krasikov A. V., Ulin I. V., Gerashchenkov D. A. et al. Formation of porous ceramic supports for catalysts by microarc oxidation. Russian Journal of Applied Chemistry. 2017. Vol. 90, No. 9. pp. 1161–1168.
14. Bespalova Zh. I., Panenko I. N. Understanding the effect of the electrolyte composition and micro-arc oxidation modes on the structure, morphology and properties of oxide-ceramic coatings. Elektronnaya obrabotka materialov. 2018. Vol. 54, No. 1. pp. 22–29.
15. Krishna L. R., Somaraju K. R. C., Sundararajan G. The tribological performance of ultra-hard ceramic composite coatings obtained through microarc oxidation. Surface and Coatings Technology. 2003. Vol. 163-164. pp. 484–490.
16. Malyshev V. N., Gantimirov B. M., Volkhin A. M., Kim S. L. Improved antifriction properties of wear-resistant MAO coatings. Chemical Physics and Mesoscopy. 2013. Vol. 15, No. 2. pp. 285–291.
17. Markov M. A., Bykova A. D., Krasikov A. V., Farmakovskii B. V. et al. Formation of wear- and corrosion-resistant coatings by the microarc oxidation of aluminum. Refractories and Industrial Ceramics. 2018. Vol. 59, No. 2. pp. 207–214.
18. Wang Y. Q., Zheng M. Y., Wu K. Microarc oxidation coating formed on SiCW/AZ91 magnesium matrix composite and its corrosion resistance. Materials Letters. 2005. Vol. 59, No. 14-15. pp. 1727–1731.
19. Ying L., Jun G. L., Ming Z. W., Zhen M. et al. Corrosion resistance of the microarc oxidation coatings prepared on magnesium alloy. E3S Web of Conferences. 2018. Vol. 38. 02009–02011.
20. Chernyshov N. S., Kuznetsov Yu. A., Markov M. A., Krasikov A. V. et al. Corrosion resistance testing of oxide-ceramic coatings produced by micro-arc oxidation. Novye ogneupory. 2020. No. 4. pp. 51–55.
21. Zhou Y. H., Chen P. H., Huang D. N., Wu Z. Z. et al. Micro-arc oxidation for improving high-temperature oxidation resistance of additively manufacturing Ti2AlNb. Surface and Coatings Technology. 2022. Vol. 445. pp. 128719–128728.
22. Curran J. A., Clyne T. W. Thermo-physical properties of plasma electrolytic oxide coatings on aluminium. Surface and Coatings Technology. 2005. Vol. 199. pp. 168–176.
23. Deev V., Prusov E., Prikhodko O., Ri E. Crystallization behavior and properties of hypereutectic Al-Si alloys with different iron content. Archives of Foundry Engineering. 2020. Vol. 20, Iss. 4. pp. 101–107.
24. Komarov A. I., Tsybulskaya L. S., Zolotaya P. S., Romanyuk A. S. et al. The structure and optical properties of composite light-absorbing coatings produced by micro-arc oxidation. Mechanics of Machines, Mechanisms and Materials. 2019. No. 4. pp. 79–83.
25. Liu J., Zhang W., Zhang H., Hu X. et al. Effect of microarc oxidation time on electrochemical behaviors of coated bio-compatible magnesium alloy. Materials Today: Proceedings. 2014. Vol. 1. pp. 70–81.
26. Pistons and engine testing. Wiesbaden : ATZ/MTZ-Fachbuch, Vieweg+ Teubner Verlag, 2012. 284 p.
27. Research services branch of the national institute of mental health. ImageJ. Available at: https://imagej.nih.gov/ij/ (Accessed: 21.03.2022).
28. GOST 9.904–82. Unified system of corrosion and ageing protection. Alluminium alloys. Accelerated test method for exfoliating corrosion. Introduced: 01.07.1983.
29. GOST R 52381–2005. Abrasive materials. Grain and grain size distribution of grinding powders. Test of grain size distribution. Introduced: 01.07.2006.
30. Zemskova E. P. Ensuring corrosion resistance of aluminium alloy parts by forming thin MAO coatings: PhD dissertation. Moscow, 2009. 281 p.
31. Kolomeichenko A. V., Chernyshov N. S., Titov N. V., Logachev V. N. Investigation of corrosion resistance of aluminum alloy products with protective coatings formed by plasma electrolytic oxidation. Surface Engineering and Applied Electrochemistry. 2017. Vol. 53, No. 4. pp. 322–326.