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.

Abstract: The present invention utilizes a novel flux-coated alloy member that is particularly adapted to be selectively positioned at the braze joints of a tube-and-center type heat exchanger. The flux-coated alloy member is suitably sized and shaped to place a predetermined quantity of flux compound and brazing alloy at the braze joints, so as to avoid the presence of excess flux compound and brazing alloy which may otherwise have a detrimental effect on the quality of the braze joints subsequently formed during a brazing operation. The flux coating of this invention is hard and durable, and is composed of potassium tetrafluoroaluminate particles which are dispersed in either a natural resin or a water soluble epoxy resin.

Abstract: An improved method for assembling a brazed heat exchanger unit suitable for use in an automobile air conditioning system. Prior to assembly, a sufficiently viscous flux-brazing composition is selectively applied to the internal and external features of the heat exchanger which serve as the joining surfaces of the heat exchanger. The flux-brazing composition is specifically applied to the internal surfaces of the aluminum alloy header and the external surfaces of the tubes so as to form uniformly and consistently brazed internal and external joints. The flux-brazing composition of this invention consists of potassium tetrafluoroaluminate particles, an aluminum-silicon powder, zinc and a binder. The flux-brazing composition enables the selective application of both a flux compound and a brazing compound, eliminating excessive use of flux and eliminating the need to clad the components of the heat exchanger with an aluminum alloy brazing material.

Abstract: A brazing paste for aluminum or aluminum alloy parts. The paste consists essentially of, by weight, between about 8 and 72 percent potassium tetrafluoroaluminate having a purity of at least about 96 percent, between about 15 and 75 percent aluminum-silicon alloy, and between about 2.5 and 50 percent organic carrier having a vaporization temperature which is below the melting temperature of the aluminum-silicon alloy, and the melting temperature of the potassium tetrafluoroaluminate being below the melting temperature of the aluminum-silicon alloy. The high purity potassium tetrafluoroaluminate has a lower melting temperature so that a greater number of aluminum-silicon alloys may be used therewith and does not have corrosive substances so that the braze can be of high quality and not require additional steps of washing and drying the brazed part for overall cost savings.

Abstract: A new and improved solder tinning paste composition suitable for use as an underlay for metallic solder when solder filling base metal braze joints to facilitate formation of the solder joint between the base metals. The paste composition comprises substantially pure tin powder, suspending agent, inorganic based flux and solvent. Optionally, the paste composition may comprise a deoxidizing agent, a soil removing agent and a surfactant.The solder tinning paste exhibits enhanced flowing and wetting characteristics and a lower melting point. In another aspect thereof, the present invention provides a process for formulating the foregoing solder paste composition.

Abstract: An improved process is disclosed for the preparation of aromatic hydrocarbon mixture from monoolefins having not more than four carbon atoms by contacting with certain crystalline silicate catalysts having certain ratio of composition to crystallite size to achieve durable selectivity.