Main process parameters and covers characteristics as criteria for evaluating the effectiveness of the of anodic micro-arc oxidation

The article is devoted to the evaluation of the feasibility and efficiency of modernization of the microarc oxidation process (MAO) by changing the conditions and parameters of sparking, as well as the selection of criteria for assessing the quality and predicting the service properties of formed ceramic-like coatings. The predominant role in changing the nature of structure formation and in ensuring the predicted quality and properties of the oxidized alloy is played by the intensity of sparking, which occurs in the process of electric discharges migrating along the treated surface of the object immersed in the electrolyte. Intensity of sparking determines the conditions for obtaining equidistant coatings: the less stochastic the nature of sparking around the oxidized part is, the more evenly and rapidly the thickness of the formed coating increases and its density is higher. These considerations allowed us offering the option of upgrading method of the anode MAO (AMAO), wherein only the anodic component of the current, causing thereby obtaining thin coatings with extensive porosity by stabilizing the process of arcing through the use of the system of quasi cathodes in the electrolysis bath. In this study, we consider the possibility of controlling the parameters of coatings obtained by the AMDO method in its standard and upgraded versions, by fixing in real time the nature of the distribution of spark discharges, indirect evidence of which is the change in the current density over time and the uniformity of the thickness of the coatings created. Taking into account the influence of micro-arc oxidation on the structural and qualitative features of formed layers, it was assumed that the surface of the coating obtained by the modernized method should have a higher quality, one of the indicators of which is a more smooth and uniform relief. Thus, another criterion for the efficiency of the modernized process can serve as amplitude and step parameters of roughness, which, without allowing an objective assessment of the microprofile of the formed coating, can give more extensive information about the nature of the increase in its thickness and quality changes, determining the level of operational capabilities of metal objects with such a coating.

micro-arc oxidation, aluminum, quasi-cathode, sparking, current density, relief, roughness

1. Mikheev A. E., Terekhin N. A., Statsura V. V., Golenkova A. A. Technological capabilities of microarc oxidation of aluminum alloys. Vestnik mashinostroeniya [Engineering Bulletin], 2003, no. 2, pp. 56–63 (in Russian).

2. Mikheev A. Ye., Statsura V. V., Nikushkin N. V. Influence of the MAO process parameters on the formation of coatings in electrolytic solutions. Materialy, tekhnologii, konstruktsii: sbornik nauchnykh trudov [Materials, technologies, designs: collection of scientific papers]. Krasnoyarsk, 1995, pp. 144–146 (in Russian).

3. Fedorov V. A., Belozerov V. V., Velikoselskaya N. D. The formation of hardened surface layers by the method of microarc oxidation in various electrolytes and when current conditions change. Fizika i khimiya obrabotki materialov = Physics and Chemistry of Materials Treatment, 1991, no. 1, pp. 87–93 (in Russian).

4. Chigrinova N. M. Intensification of processes of microplasmo spark hardening and restoration of metal products of high accuracy by electromechanical impact. Minsk, 2010. 310 p. (in Russian).

5. Chigrinova N. M., Vorob'eva E. I. The effect of quasicathodes on the formation of equal-thickness layers during microarc oxidation of valve metals. Nauka – obrazovaniyu, proizvodstvu, ekonomike: materialy 16-i Mezhdunarodnoi nauchno-tekhnicheskoi konferentsii, Minsk, 25 yanvarya 2018 g. [Science – Education, Production, Economics: Proceedings of the 16th International Scientific and Technical Conference, Minsk, January 25–27, 2018]. Minsk, Belarusian National Technical University, 2018, pp. 346–349. (in Russian).

6. Tabenkin A. N., Tarasov S. B., Stepanov S. N. Tabachnikova N. A. (ed.). Roughness, waviness, profile. International experience. St. Petersburg, Polytechnic University Publ., 2007. 136 p.(in Russian).

7. Dagnall H. M. A. Exploring Surface Texture. Leicester, England, Rank Taylor Hobson, 1980. 170 p.