The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 02, 1996
Filed:
Aug. 30, 1994
Brian B Bonner, Nesquehoning, PA (US);
Diwakar Garg, Emmaus, PA (US);
Kerry R Berger, Lehighton, PA (US);
Air Products And Chemicals, Inc., Allentown, PA (US);
Abstract
The present invention discloses a novel, moisture-free atmosphere for brazing carbon steels that provides good braze flow and brazed joint quality with minimum or no formation of soot on brazed joints. According to the present invention, carbon steels are brazed in continuous furnaces using a moisture-free atmosphere containing a mixture of three gases including nitrogen, hydrogen, and carbon dioxide. The key features of the invention involve (1) formation of moisture, which is needed to facilitate braze flow and to minimize formation of soot on brazed joints, in-situ in the heating zone of the furnace by the reaction between hydrogen and carbon dioxide and (2) reduction in the overall amount of a reducing gas required for brazing carbon steels by keeping moisture out of the cooling zone. The use of a moisture-free three gas atmosphere has been unexpectedly found to (1) eliminate the need of an expensive and difficult to control external humidification system, (2) provide flexibility in adjusting moisture content of the atmosphere in the heating zone of the furnace simply by adjusting the flow rate of hydrogen or carbon dioxide or both, and (3) facilitate rapid conditioning of the furnace by keeping moisture out of the cooling zone. The moisture-free atmosphere has also been unexpectedly found to provide good braze flow, fillet formation, and brazed joint quality while minimizing or eliminating formation of soot on brazed joints.