| abstract |
The invention relates to an essentially chromium-free method for passivating metallic surfaces consisting of Zn, Zn alloys, Al or Al alloys, by treating the surface with an acid, aqueous preparation containing at least one essentially non-crosslinked, water-soluble polymer or copolymer comprising at least 50 wt. % of (meth)acrylic acid units, and further treatment of the surface by means of at least one water-soluble crosslinking agent comprising at least two crosslinking groups selected from the azirane, oxirane or thiirane groups. The invention also relates to passivation layers that can be obtained by means of the cited method, and to a preparation suitable for said method. |