METHOD OF OBTAINING PROTECTIVE COATING ON MAGNESIUM AND ITS ALLOYS Russian patent published in 2017 - IPC C25D11/30 

FIELD: metallurgy.

SUBSTANCE: method includes three stages: in the first step on the substrate forming a primary coating thickness of at least 15 microns, which is obtained substrate MAO in an aqueous electrolyte containing from 10 to 40 g/l of alkali metal metasilicate, 2 to 10 g/l fluorides of alkali metals and from 3 to 15 g/l of alkali metal hydroxides, for a pulse current with an amplitude of 400-450 V, 250-350 ms pulse duration, the second step is carried out first chemical bleed coating in an aqueous solution containing from 0.5 to 1.5 mol/l phosphoric acid, 0.5 to 1.5 m l/l hydrogen fluoride or fluoride, is then formed on the substrate with a secondary coating using an electrolyte and MAO mode of the first stage, after which the second chemical is carried bleed coating in an aqueous solution of the first etching, and in the third stage, an electrolyte and a first-stage MDO are used, with the formation of a final nanostructured non-metallic inorganic protective coating on the substrate.

EFFECT: increasing the adhesion strength of the coating to the substrate, corrosion resistance and resistance to external factors, primarily external mechanical influences.

4 cl, 2 dwg, 1 tbl