Solvay Fluor Gmbh

Solvay Sa

Solvay Fluor Und Derivate Gmbh

Solvay Pharmaceuticals, Gmbh

Solvay Fluor and Derivative Gmbh

Gaskatel Gesellschaft Für Gassysteme Durch Katalyse Und Elektrochemie Mbh

Andreas Becker

Ulrich Seseke-Koyro

Joachim Frehse

Hans-Walter Swidersky

Placido Garcia-Juan

Thomas Born

Alfred Ottmann

Holger Pernice

Marc Lacroix

Hans-Joachim Kohnke

The invention concerns a flux for brazing, a process for brazing metal parts employing said flux, a flux composition containing said flux, aluminum parts coated with said flux or said flux composition, a process for brazing and a brazed metal object obtainable by said brazing process. The flux is high in KAlFand low in KAlF.

Flux for brazing

A process for brazing of aluminium magnesium alloys is described applying a flux which comprises KAlFor CsAlFor both as major constituent. The flux further comprises at least one alkaline or alkaline earth metal compound selected from the group consisting of KAlF, CsAlF, LiAlF, CaF, CaCO, MgF, MgCO, SrF, SrCO, BaF, and BaCO. Preferably the flux comprises or consists of KAlF, CsAlF, and LiAlFand optionally contains also BaF.

Process for brazing of aluminum alloys and a flux

Aluminum parts, e.g., heat exchangers, with improved resistance towards corrosion caused by contact with stationary water or aqueous compositions such as cooling water can be obtained by addition of Li compounds in specific amounts to the flux used for brazing the parts. LiF and especially Li fluoroaluminates are very suitable. The flux and the Li salt can be dispersed in water or an aqueous composition separately.

Flux forming an insoluble brazing residue

Aluminum parts, such as heat exchangers, with improved resistance towards corrosion caused by contact with stationary water or aqueous compositions can be obtained by addition of Li compounds to the flux used for brazing such parts. LiF and especially Li fluoroaluminates are very suitable. Another aspect of the invention concerns fluxes containing Li salts and their use for brazing of aluminum parts.

Anticorrosive flux

A fine particulate flux, an aqueous flux preparation comprising this flux, a method for the manufacture of a coated part of aluminum, aluminum alloys, steel, copper or titanium using such flux, and a method for brazing parts of aluminum or aluminum alloys to parts of aluminum, aluminum alloys, steel, copper or titanium using such flux. The flux can be obtained by sieving, or it can be obtained by removing solids, e.g., in a cyclone, from the drying gases obtained when wet fluxes are dried, especially after their manufacture. Fine particulate flux increases the viscosity of flux preparations comprising the flux dispersed in water or an aqueous or liquid organic carrier.

Fine particulate flux

Fluxing agents comprising potassium fluorostannate and/or cesium fluorostannate which can be used for brazing or soldering components of aluminum or of an aluminum alloy, even by solderless brazing or soldering. Conventional fluxing agents or other fluorometallates, such as alkali metal fluorozincates and/or alkali metal fluorosilicates, can also be added to the fluorostannate-containing fluxing agent. The fluxing agents of the invention can be applied by either dry or wet fluxing methods.

Fluorostannate-containing brazing or soldering fluxes and use thereof in brazing or soldering aluminum or aluminum alloys

Novel methods for producing alkali metal fluorozincates, especially potassium fluorozincate. Products having defined particle size ranges are obtained depending on the sequence of introduction of the reactants alkali metal hydroxide, zinc oxide and hydrogen fluoride. The resulting alkali metal fluorozincates are particularly suitable for use as a fluxing agent or fluxing agent additive during brazing of aluminum or aluminum alloys and can be applied by wet or dry fluxing methods depending on the particle size of the alkali metal fluorozincate particles.

Alkali metal fluorozincate and method for producing it

Components composed of aluminum or an aluminum alloy with a coating comprising an aluminum-silicon alloy deposited thereon by applying an alkali metal fluorosilicate and heating the resulting treated material. The alloy layer is effectively protected against re-oxidation by a non-corrosive, alkali metal fluoroaluminate layer (e.g. a potassium fluoroaluminate layer) which forms simultaneously.

Components coated with an aluminum-silicon alloy

Components made of aluminum and aluminum alloys can be brazed at temperatures of up to 600&deg; C. using a fluxing agent composed of alkali fluorozincate or alkali fluoride/zinc fluoride mixtures. Other fluxing agents, for example those composed of potassium fluoroaluminate can be used in addition. Alkali fluorozincate fluxing agents, especially potassium and cesium fluorozincate fluxing agents, act not only as a fluxing agent but also improve the surface quality since zinc and alkali fluoroaluminates are deposited on the surface of the components. The invention also relates to new fluxing agents containing alkali metal fluorozincates.

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Lachendorf, Germany

Andreas Becker