PRE-TREATMENT COMPOSITIONS AND METHODS FOR SUBSTRATE PROCESSING Russian patent published in 2019 - IPC C23C22/34 C23C22/36 C23C22/83 

FIELD: metallurgy.

SUBSTANCE: invention relates to compositions for preliminary treatment of metal substrate, method of processing metal substrate and metal substrate with coating. Preprocessing composition contains (a) Group IIIB metal and/or Group IVB metal, (b) a compound containing at least six groups of phosphorus-containing acid or salts thereof, and (c) an electropositive metal selected from nickel, copper, silver, gold and mixtures thereof, in an ionic form, the molar ratio (a) to (b) being at least 3:1. Pre-treatment composition contains said IIIB metal group and/or IVB group metal in total amount of 20–1000 ppm (in terms of elementary metal), based on total weight of pre-treatment composition, and contains said compound containing at least six groups of phosphorus-containing acid or salts thereof, in amount of 1.82 × 10^-4 mol per liter up to 2.73 × 10^-2 mol per liter of pretreatment composition, wherein composition is substantially free of silicon and is substantially free from metals of group VB.

EFFECT: invention enables to solve environmental problems associated with use of chromates while providing a composition for pretreatment of a metal substrate which imparts properties of corrosion resistance, comparable or even superior properties of corrosion resistance, obtained by using phosphate- or chromium-containing conversion coatings.

15 cl, 11 tbl, 1 dwg