PROCEDURE FOR APPLYING COATING Russian patent published in 2010 - IPC C25D11/08 C25D15/00 

FIELD: machine building.

SUBSTANCE: procedure consists in oxidation during 40…90 min at current density 25…35 A/dm² in electrolyte on base of caustic potash 3…5 g/l and boric acid 20…40 g/l. In the process of oxidation oxygen under pressure is supplied onto surface of a part via a sprayer contacting a cathode. Oxygen is supplied at temperature 5…15°C at consumption rate 0.1-1.0 m³/min per one square metre of oxidised surface. The part contacting an anode is driven to progressive and rotary motions. Oxidised surface is located at 10…30 mm from the sprayer. Also α-Al₂O₃ (30…70 g/l) in form of fine dispersed particles of 5…7 mcm dimension and chromium oxide Cr₂O₃ (1…2 g/l) are introduced into applied electrolyte. Upon oxidation there is performed pulse heating of 5…10 cycles. Each cycle consists in conditioning during 15…20 sec at temperature 750…800°C and in cooling to temperature not above 300°C.

EFFECT: increased thickness, hardness, electric resistance of coating and increased efficiency.

1 tbl, 2 dwg, 1 ex