COMPOSITION FOR TREATMENT OF METAL SURFACE, METHOD OF SURFACE TREATMENT OF METALS USING IT, AND FILM OBTAINED BY SURFACE TREATMENT OF METALS USING IT Russian patent published in 2013 - IPC C25D13/10 

FIELD: metallurgy.

SUBSTANCE: composition for electrolytic deposition of the film containing bismuth and resin onto metal surface contains 5 to 30 wt % of non-ionic and/or cationic resin on water basis, 100 to 1000 ppm of ions of trivalent Bi and aminopolycarboxylic acid in the amount that is 0.5-10-fold to molar concentration of Bi ions. The method involves submersion of metal material with cleaned surface into composition, performance of electrolysis stage (1), at which electrolysis is performed using metal material as a cathode at the voltage of 0 to 15 V during 10 to 120 seconds, and then, electrolysis stage (2) at the voltage of 50 to 300 V during 30 to 300 seconds, washing and hardening of the deposition by heating. The obtained film contains bismuth and resin; with that, metallic Bi and oxidised Bi is deposited in terms of Bi, in the amount of 20 to 250 mg/m². Total film thickness is 5 to 40 mcm, and amount of deposited Bi from the film centre as to thickness to the side facing the metal material equals to ≥ 55% of total amount of deposited Bi.

EFFECT: formation of films providing corrosion stability to metal materials, and especially to metal structures of a composite shape, by single submersion stage.

4 cl, 1 tbl, 3 dwg