Solvay Fluor Und Derivate Gmbh

Kali-chemie Aktiengesellschaft

Ruediger Sander

Werner Rudolph

Heinz-Joachim Belt

Alfred Borinski

Alf Schulz

Dieter Naumann

Bernd Wilkes

Ralf Herkelmann

The production of a potassium fluoroaluminate having a low melting point, which can be used as a flux when soldering aluminum. The potassium fluoroaluminate is prepared in an aqueous medium from aluminum hydroxide, hydrogen fluoride and potassium hydroxide in a molar ratio of aluminum:fluorine:potassium of approximately 1:5:2. After drying at 80&deg; C. under vacuum, the resulting potassium fluoroaluminate has a differential scanning calorimetry melting point of about 548&deg; C.

Low-melting potassium fluoroaluminate

A flux which contains irreversibly dehydrated K,AlF,, for soldering light metal materials, in particular aluminum. The flux has the advantages of forming a very uniform flux coating on the workpiece or workpieces to be soldered and exhibiting outstanding flow of the solder. An appropriate soldering process, an aqueous flux suspension and preparation processes for the flux are also disclosed.

Flux suitable for soldering light metals such as aluminum

Process for preparing flux suitable for soldering light metals such as aluminum

The production of a potassium fluoroaluminate having a low melting point, which can be used as a flux when soldering aluminum. The potassium fluoroaluminate is prepared in an aqueous medium from aluminum hydroxide, hydrogen fluoride and potassium hydroxide in a molar ratio of aluminum:fluorine:potassium of approximately 1:5:2. After drying at 80.degree. C. under vacuum, the resulting potassium fluoroaluminate has a differential scanning calorimetry melting point of about 548.degree. C.

A flux which contains irreversibly dehydrated K.sub.2 AlF.sub.5, for soldering light metal materials, in particular aluminum. The flux has the advantages of forming a very uniform flux coating on the workpiece or workpieces to be soldered and exhibiting outstanding flow of the solder. An appropriate soldering process, an aqueous flux suspension and preparation processes for the flux are also disclosed.

Metal structures, e.g. coolers or heat exchangers, can be produced by placing together metal components coated with solder, dipping them into a slurry of a flux, and soldering them by heating. Alternatively, components coated with solder can also be coated with flux, then placed together to form the metal structure and soldered by heating. In this case, however, the flux must be applied so as to adhere securely, and to this end in the prior art the flux has been 'glued on' to the metal surface by organic or other binders, which when burned out during the soldering process can produce undesirable exhaust gases or emissions. The present invention discloses a metal component which is provided with a sintered flux coating which adheres without binder. The coating can optionally also contain solder metal or other auxiliaries dispersed therein. The coating is applied, for example, by contacting the metal component with a binder-free slurry of the flux or dry coating the metal component electrostatically, and then heating the coated component while avoiding melting of the flux, so that an adherent sintered flux coating is formed on the metal component. The use of these coated metal components for the production of soldered metal structures and metal structures obtained using such components are also described. Potassium fluoroaluminate flux is particularly advantageously used.

Flux-coated metal components

A method for stabilizing and/or purifying perfluoroalkanes, particularly from perfluoroalkanes which contain polyfluoroalkane by-products from their production process, in which the perfluoroalkanes are stabilized and/or purified by reacting the polyfluoroalkane(s) with fluorine at elevated pressure and temperature, to obtain perfluoroalkanes which are substantially free of polyfluoroalkanes. The method has the advantage that the perfluorination takes place rapidly and without significant formation of by-products or decomposition products.

Production of perfluoroalkanes

A process for producing N-fluorosulfonamides by reaction of a sulfonamide with fluorine in a solvent mixture of halogenated hydrocarbon an nitrile is described together with new N-fluorosulfonamides which are produced in accordance with this process.

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Sehnde, Germany

Ruediger Sander