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AssigneeAmerican Research Corporation of Virginia
InventorsRussell J. Churchill, Usha Varshney, Howard P. Groger, James M. Glass
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The laser brazing of the present invention offers the unique advantage of producing a high temperature hermetic bond while limiting the heat affected zone to the region of the joint. Laser brazing joins infrared (IR) and radio frequency (RF) ceramic materials to metals for radome applications. Using AG--Cu--Ti brazing alloys, zinc sulfide (ZnS) infrared windows were laser brazed to cylindrical titanium housings with no thermal degradation observed in crystalline properties of ZnS. Innovative glass-ceramic materials were also used as braze filler to produce over 30 ceramic-to-metal couples, including titanium Zns, Pyroceram/Kovar and niobium/sapphire. Benefits are in the production of strong, high temperature, hermetically sealed joints in aircraft and high velocity missile systems. An optimized laser brazing system is provided.
A method of forming a brazed joint between a ceramic material and a metal structure with a braze filler comprising:
The method of joining and sealing, comprising placing a circuit medium on a metallic or ceramic substrate, placing a ceramic glass brazement on the medium and substrate, heating the substrate, medium and brazement to a temperature below a melting temperature of the brazement, traversing the substrate with a high energy beam while relatively moving the substrate and the beam, heating the brazement to a melting temperature of the brazement and melting the brazement, discontinuing the beam, cooling the brazement and solidifying the brazement, reducing temperature of the substrate, medium and brazement while continuing heating, reducing heating and cooling the substrate medium and brazement and thereby joining the medium to the substrate.
Dependencies are inferred from the claim text.