METHOD FOR OBTAINING PROTECTIVE SUPERHYDROPHOBIC COATINGS ON ALUMINUM ALLOYS Russian patent published in 2022 - IPC C25D11/04 

FIELD: protective coatings.

SUBSTANCE: invention relates to the production of protective superhydrophobic coatings on structures and carcasses made of aluminum alloys, mainly containing magnesium, that prevent contact with a corrosive environment and the formation of an ice crust with high adhesion strength to the surface of structures. The method includes the treatment of the alloy surface by plasma-electrolytic oxidation (PEO) in the mode of plasma micro-discharges with variable polarization of the treated surface in an electrolyte containing potassium hydroxide and sodium liquid glass, subsequent application of a fluoropolymer layer to the formed PEO coating by immersion in the dispersion of ultrafine polytetrafluoroethylene UPTFE in an organic solvent followed by drying, at the same time, during anode polarization, the voltage value is initially increased at a rate of 0.78-0.88 V/s from 30 to 500-560 V and the further PEO process is carried out at the voltage value reached, and in the cathode phase the process is carried out in the galvanostatic mode at a current density of 0.10-0.15 A/cm², while the electrolyte additionally contains sodium fluoride and sodium tetraborate, g/l: Na₂SiO₃ (n=2.5) 10-50; KOH 1-5; NaF 1-5; Na₂B₄O₇-10H₂O 10-30, and immersion in the dispersion is carried out for 4-5 s, and the dispersion contains polyvinylidene fluoride PVDF (C₂H₂F₂-)_n in an amount of 5-8 wt. %, UPTFE in the calculated amount, providing the weight ratio of PVDF:UPTFE=1:(1-5), and N-methyl-2-pyrrolidone (C₅H₉NO)_n as an organic solvent.

EFFECT: increase in corrosion resistance and improvement of anti-icing properties of composite fluoropolymer-containing coatings on aluminum alloys by forming a multi-level surface roughness of the fluoropolymer layer and reducing the contact area of the said surface with an aggressive medium.

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