Atotech Deutschland Gmbh

Andreas Noack

Jens Geisler

Björn Dingwerth

Jens Heydecke

Lee Capper

Roland Vogel

Ellen Habig

Birgit Sonntag

The invention provides a process for depositing metallic layers from acidic or alkaline zinc or zinc alloy baths containing organic additives selected from brighteners, surfactants and complexing agents, a soluble zinc salt and optionally further metal salts selected from Fe, Ni, Co, Sn salts, wherein the bath can be purified continuously so that the process can be operated without interruption, as well as apparatus for carrying out this process.

Method for continuously operating acid or alkaline zinc or zinc alloy baths

The invention relates to a method for producing a coating layer protecting against corrosion wherein a surface which is to be treated is brought into contact with an aqueous treatment solution containing chromium(III) ions and at least one phosphate compound, wherein the ratio of the molar concentration of the chromium(III) ions to the molar concentration of the at least one phosphate compound (calculated as orthophosphate) lies between 1:1.5 and 1:3. The method improves the corrosion protection of metallic, in particular, zinc-containing, surfaces provided with conversion layers. The decorative and functional properties of the surface are maintained or improved. Furthermore, the known problems resulting from the use of chromium(VI)-containing compounds or from post-treatments with polymer dispersions are avoided.

Anti-corrosion treatment for conversion layers

For producing corrosion resistant yellow passivate layers on zinc and zinc alloy surfaces, an aqueous reaction solution is utilized that contains trivalent chromium ions, at least one acid as well as at least one heteroaromatic compound selected from the group comprising nicotinic acid, the salts and derivatives thereof.

Aqueous reaction solution and method of passivating workpieces having zinc or zinc alloy surfaces and use of a heteroaromatic compound

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Berlin, Germany

Andreas Noack