WET ON WET METHOD AND CHROME-FREE ACIDIC SOLUTION FOR THE CORROSION CONTROL TREATMENT OF STEEL SURFACES

Method for the corrosion control treatment of bright metal surfaces, which at least partly represent steel surfaces, the metal surfaces being contacted with an acidic aqueous solution of a fluoro complex of at least one element M selected from the group consisting of B, Si, Ti, Zr and Hf, rinsed with water and then coated with a cathodically depositable electrodeposition coating material, a) the aqueous solution containing not more than 1 mg/l organic polymer with allylamine or vinylamine monomers, b) the aqueous solution additionally comprising at least one further component selected from the following: nitrate ions, copper ions, silver ions, vanadium or vanadate ions, bismuth ions, magnesium ions, zinc ions, manganese ions, cobalt ions, nickel ions, tin ions, buffer systems for the pH range from 2.5 to 5.5, aromatic carboxylic acids having at least two groups which contain donor atoms, silica particles having an average size below 1 mum, and c) the metal surface not being dried prior to coating with the electrodeposition coating material; acidic, chrome-free aqueous solution of a fluoro complex of at least one element M selected from the group consisting of B, Si, Ti, Zr and Hf, having a pH in the range from 2 to 5.5 for treating metal surfaces, further comprising one or more components selected from the following: tin ions, bismuth ions, buffer systems for the pH range from 2.5 to 5.5, aromatic carboxylic acids having at least two groups which contain donor atoms. ® KIPO & WIPO 2009