Solvay Fluor Und Derivate Gmbh

Solvay Fluor Gmbh

Solvay Umweltchemie Gmbh

Thomas Born

Hans-Walter Swidersky

Werner Rudolph

Johannes Eicher

Carsten Brosch

Matthias Rieland

Andreas Becker

Alfred Ottmann

Placido Garcia-Juan

Heinz-Joachim Belt

Ulrich Seseke-Koyro

Alf Schulz

Lothar Zipfel

Eckhard Hausmann

Heinz R Feist

Werner Legat

Andrea Feldmann

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 flux or a flux preparation, which contains complex alkali metal fluorides and additionally includes a water-soluble polymer, preferably polyvinyl alcohol or a polyvinyl alcohol derivative. The water-soluble polymer may be contained in the flux preparation as a granulate or powder or used as a water-soluble package for the flux or flux preparation.

Fluxing agent

Flux residues from aluminium soldering fluxes composed of alkali metal metallates, especially fluoroaluminates of the alkali metals, in particular potassium and cesium, can be recycled by adding them to the reaction mixture used for the production of hydrogen fluoride from fluorspar and sulfuric acid or oleum. In this way the fluorine content of the flux residues becomes reusable, and the anhydrite which is produced can advantageously be used for conventional purposes.

Recycling of flux material

Sulfuryl fluoride (SO.sub.2 F.sub.2) frequently contains chlorine, sulfur dioxide and other acidic impurities owing to its production. Effective purification is possible if the sulfuryl fluoride is contacted with hydrogen peroxide or a precursor thereof, preferably in an aqueous solution. The purified product is suitable as a pesticidal agent, for example.

Purification of sulfuryl fluoride

A method for aluminum brazing, in which the addition of a solder is no longer necessary. For this purpose a flux is used which contains 6 to 50 wt-% of potassium fluorosilicate and 50 to 94 wt-% of potassium fluoroaluminate. The flux can be used, for example, in the form of an aqueous suspension or paste.

Solderless aluminum brazing

A process for preparing R113a from Rl13, and R123 from R123a or R123b by rearrangement over AlCl.sub.3, in which when the reaction mixture is heated sudden start-up of the reaction, which often causes large amounts of heat to be released and the reaction to run away, is prevented by using a specially activated AlCl.sub.3, which has been activated by means of a metal halide selected from the group consisting of NaF.multidot.nHF with 0&lt;n.ltoreq.2, AgCl and FeCl.sub.3. In addition to it being considerably easier to control the reaction, shorter reaction times for the rearrangement and a decrease in the amount of by-products which are formed, are observed.

Chlorofluoro(hydro)carbon conversion process

A process for preparing R113a from R113, and R123 from R123a or R123b by rearrangement over AlCl.sub.3, in which when the reaction mixture is heated sudden start-up of the reaction, which often causes large amounts of heat to be released and the reaction to run away, is prevented by using a specially activated AlCl.sub.3, which has been activated by means of a metal halide selected from the group consisting of NaF.nHF with 0&lt;n.ltoreq.2, AgCl and FeCl.sub.3. In addition to it being considerably easier to control the reaction, shorter reaction times for the rearrangement and a decrease in the amount of by-products which are formed, are observed.

Chlorofluoro (hydro) carbon conversion process

A method of using rubber, preferably from tire recycling, for absorbing organic carboxylic acids containing from 1 to 3 carbon atoms optionally substituted with from 1 to 5 halogen atoms. Trifluoroacetic acid, for example, can be absorbed very effectively.

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Holle, Germany

Thomas Born