CAST ALLOY ON BASE OF ALUMINIUM AND PROCEDURE FOR FORMING PROTECTIVE COATING ON ITS SURFACE Russian patent published in 2011 - IPC C22C21/12 C25D11/06 

FIELD: metallurgy.

SUBSTANCE: cast alloy on base of aluminium with reduced tendency to inter-crystallite corrosion contains wt % copper 4.0-6.2, cerium 0.08-0.10, associated impurities not more, than 0.02, aluminium - the rest. The procedure for protection surfaces of items out of cast alloy on base of aluminium with reduced tendency to inter-crystallite corrosion by means of application of coating by micro-plasma oxidation consists in oxidation of an item, corresponding to working electrode, and in alkali water solution of electrolyte containing 0.1-0.6 g/l of chemical compounds forming polymer-ions in alkali water solution. Also, oxidation is carried out at alternate symmetrical voltage spontaneously changed into asymmetrical; while duration of oxidation is equal to time when amount of intense glowing micro-discharges on surface of the item in anode half-period of alternate current flow is from 4 to 20 of micro-discharges.

EFFECT: reduced inter-crystal corrosion of aluminium alloys and reduced rate of its behaviour; production of wear resistant poor-porous external layer of coating.

3 cl, 1 tbl, 2 ex