SYSTEM AND METHOD FOR TWO STAGE PRE-TREATMENT Russian patent published in 2021 - IPC C23C22/12 C23C22/13 C23C22/56 C23C22/66 C23C22/73 C23C22/78 C23C22/83 

FIELD: metalwork.

SUBSTANCE: group of inventions relates to a system of compositions for surface treatment of a polymetallic product, a method for surface treatment of a polymetallic product and variants of processed polymetallic products. The system of compositions contains (a) a first conversion composition for contacting with at least a portion of the surface containing phosphate ions and zinc ions and substantially free of fluoride, which means less than 5 ppm fluoride based on the total weight of the conversion composition, and (b) a second conversion composition for treating at least a part of the surface, containing cations of a metal of the lanthanide family and an oxidizing agent, and / or (c) a third conversion composition for treating at least a part of the surface, containing an organophosphate compound, an organophosphonate compound, or combinations thereof.

EFFECT: imparting corrosion resistance to the surface of polymetallic products that is equivalent to or even superior to the corrosion resistance imparted by the use of phosphate or chromium-containing conversion coatings, as well as reducing creep after skibing on the surface.

22 cl, 14 tbl, 4 ex