Özet:

The influence of electrolyte composition and electrolysis modes on the surface morphology, growth kinetics, phase-structural state, and mechanical properties of MAO coatings on the V95 aluminum alloy (with Zn as the main alloying element) was studied. The possibility of forming a continuous MAO coating on the V95 alloy with a base layer thickness of more than 100 μm and a surface roughness of less than 5 μm was found. The study of the growth kinetics of MAO coatings on the V95 alloy showed that the highest growth rate of the base coating layer (about 0.83 μm/min) occurs in the 1 g/L KOH+6 g/L Na2SiO3 electrolyte. Although an increase in the relative content of the silicate component (Na2SiO3) provides a fairly high growth rate of the coating, the growth rate of the base layer remains rather low (0.38–0.40 µm/min). This makes the oxidation process in these electrolytes less technological.The study of the phase-structural state of the base coating layer showed that it has a crystalline structure, in which the main phase is aluminum oxide γ–Al2O3 (90–97 %). Crystallites of α-Al2O3 and mullite (3Al2O3∙2SiO2) are formed as the second phase. With an increase in process time in electrolytes with the highest relative content of the alkaline component (1 g/L KOH+6 g/L Na2SiO3), the relative content of the hardest α-Al2O3 phase increases (up to 5 %). The hardness of such coatings with an oxidation time of 180 minutes reaches 14,000 MPa. Thus, the study has shown the advisability of using MAO treatment for the V95 alloy, since it can significantly increase the surface hardness and thereby guarantee its high wear resistance. The combination of high hardness with a relatively high coating growth rate makes it possible to recommend oxidation in the 1 g/L KOH and 6 g/L Na2SiO3 electrolyte as the most technologically advanced for improving the mechanical characteristics of the surface of products made of V95 alloy Author Biographies Valeria Subbotinа, National Technical University "Kharkiv Polytechnic Institute" Kirpichova str., 2, Kharkiv, Ukraine, 61002 PhD, Associate Professor Department of Materials Science

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