Metallgesellschaft Aktiengesellschaft

Occidental Chemical Corporation

Oxy Metal Industries Corporation

Gerhard Muller

Werner Rausch

Dieter Hauffe

Thomas Kolberg

Horst Gehmecker

Gudrun Volling

Peter Schubach

Klaus Bittner

Thomas Wendel

Klaus Wittel

Dirk Meyer

Josef Rothkegel

Helmut Schumichen

Rainer Kuhna

The invention is in a composition and process for the chromium free passivating postrinsing of conversion layers on metals before the application of a paint or adhesive. The conversion layers can be on the bases of phosphate layers, at least two polyvalent metal ions with complex formers, titanium, zirconium and/or hafnium. The postrinsing agent is an aqueous solution which has been adjusted to a pH value of up to 5 and which contains an aluminum fluorozirconate having an Al:Zr:F mole ratio of (0.15 to 8.0):1:(5 to 52), and in which solutions the total concentration of Al+Zr+F is 0.1 to 8.0 g/l. The postrinsing solutions may additionally contain at least one of the anions benzoate, caprylate, ethyl hexoate, salicylate in a total concentration of 0.05 to 0.5 g/1 and may preferably be adjusted to the required pH value with cations of volatile bases, such as ammonium, ethanolammonium and di- and triethanolammonium. The paint is subsequently applied suitably by cathodic electrocoating or powder coating or from a low-solvent high-solids paint. The rinsing treatment is over a period of 1 to 120 seconds at temperatures of 20.degree. to 80.degree. C. The invention is used as a pretreatment to the application of a paint coating, film coating or adhesive coating.

Process for a passivating postrinsing of conversion layers

Disclosed is a composition and a process of using the composition for phosphating a workpiece made of steel or partly galvanized steel in preparation for electro-immersion painting. The cleaned and rinsed workpiece is first activated with a weakly alkaline aqueous solution which contains titanium phosphate and is subsequently dipped into an acid aqueous phosphating solution at a temperature of from 40.degree. to 60.degree. C. which contains

Process of phosphating before electroimmersion painting

Disclosed is a process for phosphating a galvanized surface, particularly of galvanized steel wherein the surface is contacted for up to 10 seconds with a phosphating solution which contains accelerator, particularly nitrate,

Phosphating process

For phosphating metal surfaces which consist at least in part of aluminum, by means of phosphating solutions which contain zinc, phosphate and fluoride, any titanium which has entered the phosphating solution and would disturb the formation of the layer is precipitated by an addition of SiO-containing compounds and after the precipitate has been removed, the content of free fluoride is readjusted to the required concentration. Particularly suitable compounds which contain SiO, consist of alkali metasilicate, alkali orthosilicate and/or alkali disilicate, preferably used in an amount of 0.05 to 1 g/l of the phosphating solution, or of silica, which is preferably used in an amount of 0.5 to 10 g per liter of the phosphating solution (calc. as Si).

Disclosed is a process of producing a phosphate coating on a composite part consisting of steel and galvanized steel, which comprises alkaline cleaning, rinsing with an aqueous rinsing bath, and phosphatizing with an aqueous zinc phosphate solution. The formation of a non-uniform coating and of spots is avoided in the process of the invention by the use of a rinsing bath which contains at least 0.2 g/l alkali borate, at least 0.1 g/l alkali silicate and at least 0.05 g/l alkali nitrite, and which preferably contains said components in a total up to 5 g/l. If the composite part is to be activated with an activating bath which contains titanium phosphate before being contacted with the zinc phosphate solution, the activating bath must contain at least 1 g/l and preferably up to 4 g/l of tetraalkalipyrophosphate. The process of the invention can be used to prepare composite parts of steel and galvanized steel for subsequent painting, particularly by electrophoretic dip painting.

Process of producing phosphate coatings

A process of electrodepositing zinc on steel wherein zinc-containing aqueous sulfuric acid electrolytes are used which contain one or more oxyacids of sulfur in which the sulfur has an oxidation number from +5 to +1. The phosphatizing of the resulting zinc coatings results in phosphate coatings which are virtually free of spots. Suitable oxyacids are sulfurous acid (H.sub.2 SO.sub.3), sulfoxylic acid (H.sub.2 SO.sub.2), hyposulfurous acid (H.sub.2 S.sub.2 O.sub.4) and/or thiosulfuric acid (H.sub.2 S.sub.2 O.sub.3) in the form of acids, salts and acid anhydrides. The oxyacids should be present in the electrolyte in a concentration of 0.05 to 10 g/l, preferably 0.1 to 2 g/l.

Method of electrodepositing zinc on steel prior to phosphating

A process for the phosphatizing of metals, particularly iron, steel and zinc, in which the metal is contacted with acidic aqueous zinc phosphate solutions, containing an oxidizing agent, which contain

Process for phosphatizing metals

A composition for the phosphatizing of metals, particularly iron and steel, which comprises an aqueous acidic, chlorate-containing zinc phosphate solution which contains

Composition and process for the phosphatizing of metals

A new composition and process provide improved phosphate treatment prior to cathodic electropainting. The surface is contacted with an aqueous acidic zinc phosphate solution having a weight ratio of Zn:PO.sub.4 of 1:12-110 and 0.3 to 2.0 g/l fluoborate prior to electropainting.

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Hanau am Main, Germany

Gerhard Muller