Morphology, structure, and phase composition of microplasma coatings formed on Al-Cu-Mg alloy

Abstract

Results of studies that relate the stages of coating formation with the properties of the coatings, formed on an aluminum alloy of the Al-Cu-Mg system from silicate alkaline baths by asymmetric ac current, are presented. The specific features are elucidated and the sequence in the formation of layered coatings and their phase composition is shown. The dependences of the limiting thickness of the overall coating, as well as a layer strengthened on the current asymmetry, are found. The coatings are characterized by the nonuniform distribution of microhardness not only along the surface but also throughout the coating thickness, which is caused by the structural heterogeneity and the phase composition, which in turn, are related with the peculiarities of the coating formation by asymmetric ac current.