Press separator for fuel cell

Abstract

A press separator made of a stainless steel sheet, for providing excellent corrosion resistance and electric conductivity by a combination of a passive coating and a deposition of boride or boron carbide, restriction corrosion without separation or coming-off, by press forming, of depositions, and ensuring an extended service. A stainless steel sheet, containing 0.005-1.5 wt. %, of B and having deposited on the surface thereof at least one kind out of M 23 (C, B) 6 type boron carbide, and M 2 B type and MB type borides, is press-formed in a corrugated shape having continuous irregularities, with angles of bent portions formed by bending or unbending by press forming being set at at least 15 degrees and an outward bending R-value at up to 1 mm.

1 . A press separator for a fuel cell made of a stainless steel plate comprising B by 0.005 to 1.5 wt. %, precipitating at least one of M 23 (C, B) 6  type boron carbide, M 2 B type, and MB type borides on the surface, and being press formed in continuous corrugations, 
 wherein angle of a bent portion formed by folding or elongating in press forming is 15 degrees or more, and outer bending radius R is 1 mm or less.    
   
   
       2 . (canceled)  
   
   
       3 . A press separator for a fuel cell made of a ferritic stainless steel comprising B: 0.005 to 1.5 wt. %, C: 0.15 wt. % or less, Si: 0.01 to 1.5 wt. %, Mn: 0.01 to 1.5 wt. %, P: 0.035 wt. % or less, S: 0.01 wt. % or less, Al: 0.001 to 0.2 wt. %, N: 0.035 wt. % or less, Cu: 0 to 1 wt. %, Ni: 0 to 5 wt. %, Cr: 17 to 36 wt. %, Mo: 0 to 7 wt. %, and balance being Fe and inevitable impurities, with contents of Cr, Mo, and B satisfying the following formula:  
       Cr(wt. %)+3×Mo(wt. %)−2.5×B(wt. %)≧17,  
     precipitating at least one of M 23 (C, B) 6  type boron carbide, M 2 B type, and M 2 B type borides on the surface, and being press formed in continuous corrugations, 
 wherein angle of a bent portion formed by folding or elongating in press forming is 15 degrees or more, and outer bending radius R is 1 mm or less.  
 
   
   
       4 . A press separator for a fuel cell made of a bright annealed stainless steel plate comprising B by 0.005 to 1.5 wt. %, precipitating at least one of M 23 (C, B) 6  type boron carbide, M 2 B type, and MB type borides on the surface, and being press formed in continuous corrugations, 
 wherein angle of a bent portion formed by folding or elongating by press forming is 15 degrees or more, and outer bending radius R is 1 mm or less.    
   
   
       5 . (canceled)  
   
   
       6 . A press separator for a fuel cell made of a bright annealed ferritic stainless steel comprising B: 0.005 to 1.5 wt. %, C: 0.15 wt. % or less, Si: 0.01 to 1.5 wt. %, Mn: 0.01 to 1.5 wt. %, P: 0.035 wt. % or less, S: 0.01 wt. % or less, Al: 0.001 to 0.2 wt. %, N: 0.035 wt. % or less, Cu: 0 to 1 wt. %, Ni: 0 to 5 wt. %, Cr: 17 to 36 wt. %, Mo: 0 to 7 wt. %, and balance being Fe and inevitable impurities, with contents of Cr, Mo, and B satisfying the following formula:  
       Cr(wt. %)+3×Mo(wt. %)−2.5×B(wt. %)≧17,  
     precipitating at least one of M 23 (C, B) 6  type boron carbide, M 2 B type, and MB type borides on the surface, and being press formed in continuous corrugations, 
 wherein angle of a bent portion formed by folding or elongating in press forming is 15 degrees or more, and outer bending radius R is 1 mm or less.