Formation of microplasma coatings on high-silicon aluminum alloy and their characteristics

• Published in: Protection of metals and physical chemistry of surfaces 2012, Vol.48 (1), p.86-96
• Main Authors: Slonova, A. I., Terleeva, O. P., Belevantsev, V. I., Rogov, A. B.
• Format: Article
• Language: English
• Subjects: Aluminum base alloys; Amorphous structure; Characterization and Evaluation of Materials; Chemistry and Materials Science; Coatings; Constraining; Corrosion and Coatings; Crystal structure; Fragments; Industrial Chemistry/Chemical Engineering; Inorganic Chemistry; Materials; Materials Science; Metallic Materials; Microplasmas; New Substances; Silicon; Tribology
• ISSN: 2070-2051; 2070-206X
• DOI: 10.1134/S207020511201011X

This work presents the results of studying the electrochemical microplasma formation of coatings based on the AK21 alloy of hypereutectic composition in silicate-alkali electrolyte. It is found that the boundary size of primary silicon inclusion in the alloy and additional cathodic surface treatment affect significantly the shape of voltage chronograms and growth dynamics of the coating thickness. It is shown that thick (more than 180 μm) layered coatings with a mosaic inner layer structure formed by fragments on the basis of the aluminum forms (amorphous Al(OH) 3 , α-, δ-, γ-Al 2 O 3 ) in the matrix of amorphous SiO 2 are formed on this alloy at all the applied treatment modes and silicon crystal sizes. It is found that the coating inner layer structure is regularly related to the limiting dimensions of primary silicon crystals. In addition, introduction of an additional cathodic component in the high-voltage polarization modes of the electrolytecoating-alloy system yielded a pronounced positive effect in the pattern of inner layer microhardness distribution that also characteristically depends on the limiting dimensions of primary silicon crystals in the initial samples.