Method of fabricating a bipolar plate assembly

Abstract

A method of fabrication is adapted to weld paired metal plates, particularly fuel cell bipolar plates, using a partial vacuum to hold the paired metal plates together during the welding process. Each bipolar plate has a plurality of contact surfaces for joining the paired metal plates. The contact surfaces of a first plate are co-aligned with contact surfaces of a second plate. An outer perimeter and a plurality of reactant gas channels and ports of each plate pair are sealed to form a sealable interior volume. A partial vacuum is drawn in the interior volume to clamp each plate pair together at the contact surfaces and a weld joint is made between at least a plurality of the contact surfaces. Laser welding is preferably used for its ability to fuse the contact surfaces together without perforating the plates and thereby losing the partial vacuum.

1 - 19 . (canceled)  
     
     
         20 . A bipolar plate assembly comprising: 
 a first plate having a first plate interior face and a first plate exterior face, said first plate interior face having a plurality of coolant flow channels formed thereon and said first plate exterior face having a plurality of reactant gas flow channels formed thereon;    a second plate having a second plate interior face and a second plate exterior face, said second plate interior face having a plurality of coolant flow channels formed thereon and said second plate exterior face having a plurality of reactant gas flow channels formed thereon, said first and second plate interior faces being positioned in an adjacent facing relationship;    at least one sealable joint interposed between said first and second plates to define an interior volume of joined coolant flow channels there between;    said interior volume having an internal pressure therein lower than an external pressure surrounding said first and second plates for drawing said first and second plates together to form multiple contact surfaces there between; and    a weld zone formed at a plurality of said contact surfaces.    
     
     
         21 . The bipolar plate assembly of  claim 20 , comprising at least one spacer plate disposed between said two plates in said interior volume such that said plurality of contact surfaces are formed between each of said two plates and said at least one spacer plate.