Abstract: A method for repairing and joining aluminum alloy articles and structures, such as heat exchangers for use in automotive applications. The method utilizes a flux-coated soldering rod (10) that is used to deliver a solder alloy (12) and a flux compound to a region to be repaired. The flux compound has a higher melting temperature than the solder alloy (12), and is present as a coating (14) that sufficiently thermally insulates the alloy (12) to cause the flux compound and the solder alloy (12) to melt nearly simultaneously during the soldering operation. The solder alloy (12) is preferably a zinc-aluminum alloy, while the flux coating (14) preferably contains a cesium-aluminum flux compound such as potassium cesium tetrafluoroaluminate, dispersed in an adhesive binder that will readily volatilize or cleanly burn off during the soldering operation.

Abstract: A method for repairing and joining aluminum alloy articles and structures, such as heat exchangers for use in automotive applications. The method utilizes a flux-coated soldering rod (10) that is used to deliver a solder alloy (12) and a flux compound to a region to be repaired. The flux compound has a higher melting temperature than the solder alloy (12), and is present as a coating (14) that sufficiently thermally insulates the alloy (12) to cause the flux compound and the solder alloy (12) to melt nearly simultaneously during the soldering operation. The solder alloy (12) is preferably a zinc-aluminum alloy, while the flux coating (14) preferably contains a cesium-aluminum flux compound such as potassium cesium tetrafluoroaluminate, dispersed in an adhesive binder that will readily volatilize or cleanly burn off during the soldering operation.

Abstract: An improved method is provided for producing an aluminum tube of the type used as cooling tubes for heat exchangers, and particularly automotive heat exchangers. The method utilizes a flux-containing composition that can be selectively deposited in a manner that permits the manufacture of aluminum tubes having a lockseam construction. As a result, the method made possible by this invention provides for the manufacture of heat exchanger tubes that offer the weight, durability and safety advantages of aluminum alloy construction, but at lower investment, processing and material costs as compared to prior art welded aluminum tubes. Another advantage of the present method is that minimal amounts of braze alloy and flux are required, yet uniform and consistent brazed joints can be produced to yield leak-proof brazed assemblies.