Elemental Composition and Microhardness of the Coatings Prepared on Faced Aluminum Alloys by Plasma Electrolytic Oxidation in a Silicate–Alkaline Electrolyte

Resumo

Owing to their high microhardness, corrosion resistance, and heat resistance, the oxide ceramic coatings formed by plasma electrolytic oxidation (PEO) find ever-growing usage for various purposes in many industries and, in particular, for maintenance. One of the methods widely used for the maintenance of aluminum alloys products is argon-arc facing. As the materials for facing, alloys of various grades, such as AK9M2, AK5, and AMr6, are used. The electrolytes widely used for PEO are aqueous silicate–alkaline electrolytes, in particular, KOH—Na₂SiO₃. To find a correlation between the chemical composition of an oxidized faced aluminum alloy and the microhardness of coatings formed on the alloy, X-ray spectrometry analysis is performed. The performed analysis and the determined distribution of chemical elements across the coating thickness allow us to estimate the mechanism of plasma electrolytic oxidation and the correlation between the electrolyte composition, the chemical composition of faced aluminum alloy, and the element composition of the hardened layer.