Flux composition for aluminum brazing
First Claim
1. A flux composition comprising:
- a flux material consisting essentially of potassium tetrafluoroaluminate;
a carrier system;
a binder present in an amount which is sufficient to substantially prevent the flux composition from separating from suspension; and
a liquid medium.
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Accused Products
Abstract
An improved flux composition is provided which is formulated for use in the brazing of aluminum alloy components, such as in the assembly of brazed heat exchanger units used in automotive applications. The flux composition is in a concentrated form, permitting its selective application to the joint surfaces of a heat exchanger'"'"'s subcomponents, and contains a flux material which consists essentially of potassium tetrafluoroaluminate, a carrier system such as a glycerol-ethylene glycol system, a binder, and a liquid medium such as water. Most preferably, the potassium tetrafluoroaluminate constitutes at least about 96 percent of the flux material, and the binder is xanthan which substantially prevents the flux composition from separating during storage. The flux composition does not contain potassium aluminum fluoride. The flux composition also makes possible a method for forming a brazed heat exchanger assembly, in which the use of a clad brazing stock material for the components of the heat exchanger can be minimized or eliminated through the use of a brazing alloy preform.
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Citations
20 Claims
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1. A flux composition comprising:
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a flux material consisting essentially of potassium tetrafluoroaluminate; a carrier system; a binder present in an amount which is sufficient to substantially prevent the flux composition from separating from suspension; and a liquid medium. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A flux composition comprising:
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a flux material comprising at least about 96 percent potassium tetrafluoroaluminate; ethylene glycol; glycerol; a binder present in an amount which is sufficient to substantially prevent the flux composition from separating from suspension during storage; and water; wherein the flux composition does not produce hydrogen fluoride and potassium fluoride when heated during a brazing operation. - View Dependent Claims (8, 9, 10)
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11. A method for forming a heat exchanger having at least one tube extending from a header, the method comprising the steps of:
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forming the tube and header from aluminum alloys, the header and tube have corresponding surfaces which serve as joining surfaces therebetween, the joining surface of the header having a depression formed therein; assembling the tube and header so as to form an assembly in which a braze ring circumscribes the tube so as to reside in the depression formed in the joining surface of the header, and with a flux composition being present in the depression, wherein the flux composition comprises; a flux material consisting essentially of potassium tetrafluoroaluminate; a carrier system; a binder present in an amount which is sufficient to substantially prevent the flux composition from separating from suspension; and a liquid medium; and heating the assembly for a duration which is sufficient to melt the braze ring and the flux composition so as to braze the tube to the header to form the heat exchanger. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification