Low-cost manganese-stabilized austenitic stainless steel alloys, bipolar plates comprising the alloys, and fuel cell systems comprising the bipolar plates
Corrosion resistant, manganese-stabilized austenitic stainless steels with a low nickel content are used in bipolar plates, methods for fabricating the bipolar plates, and polymer electrolyte membrane (PEM) fuel cells comprising the bipolar plates. The bipolar plates are formed from high-manganese austenitic stainless steels comprising, in weight percents, 4.0 to 35 manganese, 0.5 to 1.5 nickel, 17 to 20 chromium, 0.2 to 0.5 nitrogen, up to 0.075 carbon, 0.5 to 1.0 silicon, up to 0.1 aluminum, 0 to 0.005 sulfur, and balance iron and incidental impurities. The steels exhibit suitable corrosion resistance, electrical contact resistance, and mechanical properties for high-corrosion applications such as use in bipolar plate materials for PEM fuel cells. The bipolar plates may comprise a solid plate of the steel, optionally coated with a highly electrically conductive material. Alternatively, the bipolar plates may comprise an economical substrate coated with the steel, optionally further coated with a highly electrically conductive material.
1. A bipolar plate comprising:
a cathode face defining at least one first flow distribution channel for at least one first reactant; and
an anode face defining at least one second flow distribution channel for at least one second reactant, wherein at least one of the cathode face and the anode face comprises a manganese-stabilized austenitic stainless steel consisting of:
from 19% to 23% by weight manganese;
from 0.5% to 1.5% by weight nickel;
from 17% to 20% by weight chromium;
from 0.2% to 0.5% by weight nitrogen;
up to 0.075% by weight carbon;
from 0.5% to 1.0% by weight silicon;
up to 0.1% by weight aluminum;
from 0% to 0.005% by weight sulfur; and
balance iron and incidental impurities.
2. The bipolar plate of claim 1 , further comprising a layer of electrically conductive material disposed on the manganese-stabilized austenitic stainless steel.
3. The bipolar plate of claim 2 , wherein the electrically conductive material is selected from the group consisting of gold, gold alloys, platinum, platinum alloys, iridium, iridium alloys, ruthenium, ruthenium alloys, rhodium, rhodium alloys, and mixtures of any of these.