METHOD OF PROTECTIVE COATING RECEIVING ON STEEL Russian patent published in 2009 - IPC C25D11/02 

FIELD: metallurgy.

SUBSTANCE: invention relates to gumming products made of steel which are exploited in corrosion-active mediums, particularly, in sea water. Method includes surface preprocessing of products by plasma-electrolytic oxidation in anode mode during 5-10 minutes at forming tension. Changing from 0 till 180-200 V at a rate of 0.2 - 0.3 V/s and further plasma-electrolytic oxidation in bipolar mode during 5-10 min at constant at anode voltage 180 - 200 V, constant cathodic current component density 0.5 - 1.0 A/cm² and ratio of duration anodic and cathodic polarisation period τ_a/τ_c = 1, with oxidise surface of products is additionally treated by means of putting of fine-grained low-molecular polytetrafluoroethylene and heating at 80 - 90°C during 50 - 70 min, and plasma-electrolytic oxidation in anodic and bipolar modes is implemented in aqueous electrolyte of the following content, g/l: Na₃PO₄ · 12H₂O 15.0 - 30.0, NaAlO₂ 10.0 - 25.0, K₄[Fe(CN)₆] 3.8 - 4.5. Method provides receiving of the plating, allowing high protective anticorrosion properties ensured by more homogeneous structure and absence of plating surface coating defect.

EFFECT: receiving of platings allowing high protective anticorrosion properties ensured by more homogeneous structure and absence of plating surface coating defect.

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