CORROSION PROTECTION OF STEEL STRIPS COATED WITH ZINC OR ZINC ALLOY

摘要

A process for the corrosion protection of steel strips coated with zinc orzincalloy, characterised in that the steel strips coated with zinc or zinc alloyare broughtinto contact with an aqueous treatment solution having a pH within the rangeof from1.5 to 3.5, which contains 1 to 20 g/l manganese(II) ions and 1 to 150 g/lphosphateions, and the solution is dried without intermediate rinsing. Optionally thesolution maycontain in addition: up to 10 g/l zinc ions, up to 10 g/l nickel ions, up to20 g/l titaniumions, up to 50 g/l silicon in the form of silicon compounds, up to 30 g/lfluoride ions, upto 150 g/l of one or more polymers or copolymers of polymerisable carboxylicacidsselected from acrylic acid, methacrylic acid and maleic acid, and estersthereof withalcohols having 1 to 6 carbon atoms. The present invention also relates to thecorrespondingly-treatedmetal strips.