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

V. S. Еgorkin, Senior Researcher, Head of the Laboratory of Electrochemical Processes, e-mail: egorkin@ich.dvo.ru
I. E. Vyalyi, Researcher of the Laboratory of Unstable Surface Processes, e-mail: igorvyal@gmail.com
S. L. Sinebryukhov, Head of the Laboratory of Unstable Surface Processes, Doctor of Chemical Sciences, Associate Professor, Corresponding Member of the Russian Academy of Sciences, e-mail: sls@ich.dvo.ru
S. V. Gnedenkov, Director, Head of the Department of Electrochemical Systems and Processes of Surface Modification, Doctor of Chemical Sciences, Professor, Corresponding Member of the Russian Academy of Sciences, e-mail: svg21@hotmail.com

The study results of the morphology, composition, electrochemical and mechanical properties of coatings formed by plasma electrolytic oxidation (PEO) on aluminum alloy AMg61 in tartrate-based electrolytes of two compositions: 20 g/l tartaric acid and 6 g/l potassium hydroxide; 20 g/l potassium tartrate and 0.6 g/l sodium fluoride. The presence of sodium fluoride in the electrolyte causes the formation of γ-modification of aluminum oxide(III) in the form of microtubules (visible porosity of 23%), while a low-porous layer of γ-Al₂O₃ is formed in the electrolyte with potassium hydroxide (visible porosity of 3%). A sample with a PEO coating formed in an electrolyte containing 20 g/l tartaric acid and 6 g/l potassium hydroxide has the best electrochemical and wear-resistant properties. Applying such a coating to the AMg61 alloy reduces the corrosion current density of the sample by more than an order of magnitude (I_k = 1.4·10^–9 A/cm²) compared with the value of this parameter for the uncoated sample (I_k = 4.8·10^–8 A/cm²). The scalar impedance at low frequency |Z|_{f = 0.01} Hz for such coating increases by three orders of magnitude (|Z|_{f = 0.01} Hz = 2.51·10⁸ ohms·cm²) compared with this parameter for an uncoated sample (|Z|_{f = 0.01} Hz = 1.94·105 ohms·cm2). Reduction by 2 times of the coefficient of friction (μ = 0.10–0.12) and decrease in the wear rate by half an order (4.8·10^–4 mm³/(N·m)) compared with the values of these parameters for a sample treated in an electrolyte with 20 g/l potassium tartrate and 0.6 g/l NaF (1.1·10^–3 mm³/(N·m) at μ = 0.23–0.26) are caused by the morphology and phase composition of the oxide layer.
The article was prepared using the results of the work carried out with the financial support of the Russian Science Foundation No. 23-23-00372 “Protective composite coating of aluminum alloys operated in marine conditions”.

1. Verma A. K., Chauhan A. K., Kumar A., Agarwal M. Exploring, characteristics and analysis of Magnalium alloy developed by the powder metallurgy process. Journal of Alloys and Compounds Communications. 2024. Vol. 3. 100010. DOI: 10.1016/j.jacomc.2024.100010
2. Konstantinov I. L., Yuryev P. O., Baranov V. N., Bezrukikh A. I. et al. Study the influence of scandium content and annealing regimes on the properties of alloys 1580 and 1581. International Journal of Lightweight Materials and Manufacture. 2023. Vol. 6, Iss. 1. pp. 15–24. DOI: 10.1016/j.ijlmm.2022.09.002
3. Gaydukova A. M., Nazarova D. Yu., Konkova T. V., Stoyanova A. D. Determining the influence of parameters of electrochemical polishing of aluminum alloys on roughness and surface reflectivity. Tsvetnye Metally. 2024. No. 8. pp. 40–47.
4. Gnedenkov S. V., Sinebryukhov S. L., Egorkin V. S., Vyalyi I. E. et al. Formation and properties of composite coatings on aluminum alloys. Russian Journal of Inorganic Chemistry. 2017. Vol. 62. pp. 1–11. DOI: 10.1134/S0036023617010065
5. Kuznecov A. O., Oglodkov M. S., Klimkina A. A. The influence of chemical composition on structure and properties of Al – Mg – Si alloy. Trudy VIAM. 2018. No. 7. pp. 3–9.
6. Egorkin V. S., Medvedev I. M., Sinebryukhov S. L., Vyaliy I. E. et al. Atmos pheric and marine corrosion of PEO and composite coatings obtained on Al – Cu – Mg aluminum alloy. Materials (Basel). 2020. Vol. 13, Iss. 12. 2739. DOI: 10.3390/ma13122739
7. Peng C., Cao G., Gu T., Wang C. et al. The corrosion behavior of the 6061 Al alloy in simulated Nansha marine atmosphere. Journal of Materials Research and Technology. 2022. Vol. 19. pp. 709–721. DOI: 10.1016/j.jmrt.2022.05.066
8. Osokin E. P., Barahtina N. N., Pavlova V. I., Alifirenko E. A., Zykov S. A. Aluminum materials in shipbuilding and the efficiency of their use in industry. Tekhnologiya legkih splavov. 2022. No. 3. pp. 69–84. DOI: 10.24412/0321-4664-2022-3-69-84
9. He Z., Zeng Y., Zhou M., Min Y. et al. Superhydrophobic films with enhan ced corrosion resistance and self-cleaning performance on an Al alloy. Langmuir. 2021. Vol. 37, Iss. 1. pp. 524–541. DOI: 10.1021/acs.langmuir.0c03222
10. Zhu T., Yuan Y., Yu Q., Xiang H. et al. Enhanced corrosion resistance of slippery liquid infused porous aluminum surfaces prepared by anodizing in simulated marine atmosphere. Materials Chemistry and Physics. 2023. Vol. 306. 128073. DOI: 10.1016/j.matchemphys.2023.128073
11. Xie C., Chen Y., Liu X., Tang W. et al. Effect of voltage and time on microstructure and corrosion resistance of anodic oxidation film on Al – 5.5Zn – 0.03In – 1Mg – 0.03Ti – 0.08Sn alloy. Journal of Alloys and Compounds. 2024. Vol. 1009. 176740. DOI: 10.1016/j.jallcom.2024.176740
12. Díaz B., Figueroa R., Nóvoa X. R., Pérez C. et al. Effect of substrate microstructure on corrosion resistance of cast and forged anodised 6082 Al alloy. Surface and Coatings Technology. 2024. Vol. 481. 130614. DOI: 10.1016/j.surfcoat.2024.130614
13. Woo Yang J., Park H., Hwan Chun H., Ceccio S. L. et al. Development and performance at high Reynolds number of a skin-friction reducing marine paint using polymer additives. Ocean Engineering. 2014. Vol. 84. pp. 183–193. DOI: 10.1016/j.oceaneng.2014.04.009
14. Cerchier P., Pezzato L., Gennari C., Moschin E. et al. PEO coating containing copper: A promising anticorrosive and antifouling coating for seawater application of AA 7075. Surface and Coatings Technology. 2020. Vol. 393. pp. 125774. DOI: 10.1016/j.surfcoat.2020.125774
15. Guo D., Zhang Y. M., Li Y., Lu B. C. et al. Hydrocarbon-degrading Shewanella algae shows oxidative deterioration corrosion at the aluminium alloy & coating interface. Corrosion Science. 2024. Vol. 234. 112072. DOI: 10.1016/j.corsci.2024.112072
16. Egorkin V. S., Gnedenkov S. V., Sinebryukhov S. L., Vyaliy I. E. et al. Increasing thickness and protective properties of PEO-coatings on aluminum alloy. Surface and Coatings Technology. 2018. Vol. 334. pp. 29–42. DOI: 10.1016/j.surfcoat.2017.11.025
17. Madhavi Y., Rama Krishna L., Narasaiah N. Corrosion-fatigue behavior of micro-arc oxidation coated 6061-T6 Al alloy. International Journal of Fatigue. 2021. Vol. 142. 105965. DOI: 10.1016/j.ijfatigue.2020.105965
18. Barati N., Jiang J., Meletis E. I. Microstructural evolution of ceramic nanocomposites coated on 7075 Al alloy by plasma electrolytic oxidation. Surface and Coatings Technology. 2022. Vol. 437. 128345. DOI: 10.1016/j.surfcoat.2022.128345
19. GOST 4784–2019. Aluminium and wrought aluminium alloys. Grades. Introduced: 1.09.2019.
20. Gnedenkov S. V., Egorkin V. S., Sinebryukhov S. L., Vyalyy I. E. Electrochemical properties of oxide coatings on AMg3 (АМг3) aluminium alloy, treated with hydrophobic agent solution. Tsvetnye Metally. 2015. No. 8. pp. 55–60.
21. Yerokhin A., Khan R. H. U. Surface engineering of light alloys: aluminium, magnesium and titanium alloys. Cambridge, UK, New Delhi, Boca Raton, FL : Woodhead Publishing Limited, 2010. 680 p.
22. Collins T. J. ImageJ for Microscopy. Biotechniques. 2007. Vol. 43. pp. 25–30.
23. Perepelkina S. Yu., Kovalenko P. P., Pechenko R. V., Nuzhdin K. A. Methodology for investigating tribological characteristics of materials on a friction machine. Izvestiya vuzov. Priborostroenie. 2016. Vol. 59. No. 8. pp. 636–640. DOI: 10.17586/0021-3454-2016-59-8-636-640
24. Measuring equipment. Supplement to Certificate No. 57801 on approval of type of measuring instruments. Devices for measuring the coefficient of friction Tribometer of models TRB, THT and VTR. Available at: https://allpribors.ru/docs/59808-15.pdf (Accessed: 25.11.2024).