Conducting plates for fuel cell elements

Abstract

The present invention relates to the use of the A286 alloy grade for the manufacture of a sheet, optionally surfaced, making it possible to obtain a conducting plate of mono polar or bipolar type for a fuel cell element. The invention also relates to this optional surface treatment process, which comprises a cold-rolling step followed by a continuous annealing step in an oxidizing atmosphere and by an acid pickling step.

1 - 17 . (canceled) 
     
     
         18 . A method for manufacturing a monopolar or bipolar conducting plate for a fuel cell element, comprising the step of providing at least one alloy having, in percentages by weight:
 24.0 to 27.0% nickel;   13.5 to 16.0% chromium;   1.90 to 2.35% titanium;   1.0 to 1.5% molybdenum;   0.10 to 0.50% vanadium;   at most 0.08% carbon;   at most 2.0% manganese;   at most 1.0% silicon;   at most 0.35% aluminium;   at most 0.03% sulphur; and   at most 0.01% boron,   
       the balance consisting of iron and impurities. 
     
     
         19 . The method of  claim 18 , wherein the alloy contains:
 24.0 to 25.5% nickel;   14.0 to 16.0% chromium;   2.00 to 2.30% titanium;   1.2 to 1.5% molybdenum;   0.10 to 0.50% vanadium;   at most 0.06% carbon;   at most 2.0% manganese;   at most 0.3% silicon;   at most 0.25% aluminium;   at most 0.01% sulphur; and   at most 0.01% boron, the balance consisting of iron and impurities.   
     
     
         20 . A sheet comprising at least one alloy as defined in  claim 18 , wherein said sheet has, at least on one of its faces, an arithmetic mean roughness Sa of 0.12 μm or higher, a maximum height amplitude St of less than 4 μm and, preferably, a developed surface area Sdr of greater than 0.2%. 
     
     
         21 . A process for surfacing a sheet based on an alloy as defined in  claim 18 , comprising the following steps in succession:
 (a) a semi-finished product chosen from a thin slab or a hot-rolled sheet is cold rolled;   (b) the sheet obtained in step (a) is continuously annealed, at a temperature between 900 and 1200° C. for a time ranging from 10 seconds to 30 minutes, in an oxidizing atmosphere; and   (c) the annealed sheet obtained from step (b) is pickled by bringing it into contact with at least one mineral acid at a temperature of between 40 and 100° C.   
     
     
         22 . The process of  claim 21 , which further includes an electrolytic pickling step. 
     
     
         23 . The process of  claim 21 , which further includes a step of rinsing, preferably with water, and then of drying the pickled sheet. 
     
     
         24 . A sheet obtainable by the process according to  claim 21 . 
     
     
         25 . A process for manufacturing a conducting plate for a fuel cell element, comprising providing the sheet of  claim 24 . 
     
     
         26 . A process for manufacturing a conducting plate for a fuel cell element, which comprises the surfacing of a sheet containing at least one alloy, having, in percentages by weight,
 24. 0 to 27.0% nickel,   13.5 to 16.0% chromium,   1.90 to 2.35% titanium,   1.0 to 1.5% molybdenum,   0.10 to 0.50% vanadium,   at most 0.08% carbon,   at most 2.0% manganese,   at most 1.0% silicon,   at most 0.35% aluminium,   at most 0.03% sulphur,and   at most 0.01% boron,   
       the balance consisting of iron and impurities, according to the process defined in  claim 21 , wherein the manufacturing process further includes at least the following steps:
 said sheet having a thickness of 0.05 to 0.5 mm, in particular 0.1 to 0.2 mm, undergoes a first deformation by means of a first tool in order to obtain a corrugated blank; and 
 said corrugated blank undergoes a second, tangential deformation by means of a second tool. 
 
     
     
         27 . The process of  claim 26 , wherein the succession of first and second deformations gives the sheet an elongation of at least 25% to 35% relative to the initial length of the sheet. 
     
     
         28 . The process of  claim 26 , wherein said sheet has, at least on one of its faces, an arithmetic mean roughness Sa of 0.12 μm or higher, a maximum height amplitude St of less than 4 μm and, preferably, a developed surface area Sdr of greater than 0.2%. 
     
     
         29 . A conducting plate for a fuel cell element, which can be obtained by the process according to  claim 26 . 
     
     
         30 . A fuel cell element comprising at least one monopolar or bipolar conducting plate comprising at least one alloy as defined in  claim 18 . 
     
     
         31 . A fuel cell element comprising at least one monopolar or bipolar conducting plate comprising a sheet according to  claim 20 . 
     
     
         32 . A fuel cell element comprising at least one monopolar or bipolar conducting plate according to  claim 29 . 
     
     
         33 . A fuel cell, in particular of the PEMFC (photon exchange membrane fuel cell) type, containing the cell element according to  claim 30 . 
     
     
         34 . A method for supplying electricity to a vehicle, such as a motor vehicle, or a telecommunication means, such as a relay antenna or a mobile telephone, comprising providing a fuel cell according to  claim 33 .