Separator for fuel cell and method for producing the same

Abstract

A separator for a fuel cell comprising a gold covering layer formed on the surface of stainless steel plate a method for producing a separator, in which exfoliation and fracture of the gold covering layer can be prevented and corrosion resistance and durability can be obtained, are provided. Voids are formed by intergranular corrosion treatment at a surface of the stainless steel plate, and the gold covering layer is formed so as to be embedded in the voids. Limit value of radius of curvature in bends in which exfoliations or fractures in the gold covering layer is formed can be reduced by satisfying the equation 0.2≦4/d/L≦80 wherein L(μm) is the average grain size of the surface of stainless steel plate, and d(μm) is the thickness of the gold covering layer.

1 . (canceled)  
     
     
         2 . (canceled)  
     
     
         3 . A method for producing a separator for fuel cell, comprising: 
 performing an intergranular corrosion treatment on a surface of a stainless steel plate;    plaiting a gold covering layer on the treated surface of the stainless steel plate; and then press forming the stainless steel plate.    
     
     
         4 . A method for producing a separator for fuel cell according to  claim 3 , wherein the separator satisfies the equation 0.2≦d/L≦(L(μm): the average grain size of the surface of stainless steel plate, d(μm): thickness of the gold covering layer).  
     
     
         5 . A method for producing a separator for fuel cell, the separator having a metallic plate of which surface is formed with a gold covering layer, the method comprising: 
 forming the gold covering layer on the surface of the metallic plate; and then    compression forming the metallic plate.    
     
     
         6 . A method for producing a separator for fuel cell according to  claim 5 , wherein the following equations  
         0.9×( dB+dS )≦ d′B+d′S    0.1 ×dS≦d′S≦ 0.9 ×dS    
       are satisfied (average thickness of the metallic plate before compression forming is dB, average thickness of the metallic plate after compression forming is d′B, average thickness of the gold covering layer before compression forming is dS, and average thickness of the gold covering layer after compression forming is d′S).