FIELD: application of protective and decorative coats on rectifying metals and their alloys, mainly application of coats on articles made from aluminum, titanium and magnesium.
SUBSTANCE: electrolyte contains sodium dihydrophosphate in the amount of 20-60 g/l and iron citrate (III) in the amount of 2-25 g/l in aqueous solution. Proposed method includes micro-arc oxidation in said electrolyte in pulse anode mode or anode-cathode mode at pulse repetition frequency of 50-2500 Hz and duration of 50-1000 mcs at anode current density of 70-300 A/dm2 and cathode current of 50-120 A/dm2. Black ceramic coat formed on rectifying metals and their alloys consists of at least two layers: functional upper layer and lower layer; thickness of inner layer is 5-10 mcm and thickness of upper functional layer is 10-40 mcm; it contains 10-50 mass-% of iron.
EFFECT: improved protective property of coats; enhanced corrosion resistance, wear resistance and heat resistance.
6 cl, 1 dwg, 3 ex
