Impact of Electrolyte Composition and Modes of Operation on the Structure, Morphology, and Properties of Oxide Ceramic Coatings Fabricated by Microarc Oxidation

Abstract

The formation of oxide coatings on D16 aluminum alloy by microarc oxidation (MAO) treatment in the anodal-cathodal mode with discharge interruption in the basic silicate-alkali electrolyte (composed of three solutions) and in the mode without charge interruption in a silicate-alkali electrolyte of similar composition is studied. We find that the mechanism of formation of oxide ceramic coatings depends on the mode of MAO treatment. Addition of sodium tetraborate to the electrolyte has an impact on the properties of oxide ceramic coatings fabricated using the mentioned treatment modes. We demonstrate that MAO treatment in the anodal-cathodal mode with discharge interruption gives rise to a higher content of high-temperature aluminum oxide phase (α-Al₂O₃) in coatings and enables the formation of thin (up to 25 μm) oxide ceramic coatings that retain all unique properties of this type of coatings.