Abstract: Microarc oxidation coatings on aluminium alloy were prepared in Na₂SiO₃ and (NaPO₃)₆ as well as NaAlO₂ aqueous solution, and the effects of electrolyte category and concentration on phase component and elementary composition were studied. The experimental results show that the content of α-Al₂O₃/ γ-Al₂O₃ is closely relative to electrolyte category and concentration. Elementary compositions of coated samples fabricated in diffe rent electrolyte solution are different, and the content of same element in surface and density layers of coatings prepared in same electrolyte are also different.

Key words: aluminium alloy, microarc oxidation, phase component, elementary composition