| 摘要 |
Alkaline aqueous composition having a pH value of at least 8.5, comprises (a) at least 0.01 g/l of iron ions, (b) one or more water soluble organic carboxylic acids comprising at least one amino group at alpha -, beta - or gamma -position relative to the acid group and/or their water-soluble salts, and (c) one or more oxoacids of phosphorus or nitrogen and/or their water soluble salts, where at least one phosphorus atom or nitrogen atom is present in an average oxidation state. An independent claim is included for pretreating galvanized steel surfaces, comprising (i) optionally cleaning and degreasing the steel surfaces using an alkaline cleaning agent, (ii) contacting the steel surfaces with the alkaline composition, and (iii) subjecting the steel surfaces to passivating wet chemical conversion coatings. |
