Protective nitride formation on stainless steel alloys for proton exchange membrane fuel cell bipolar plates

Journal Article · Sun Dec 31 23:00:00 EST 2006 · Journal of Power Sources

DOI:https://doi.org/10.1016/j.jpowsour.2007.08.106· OSTI ID:978784

Yang, Bing ^[1]; Brady, Michael P ^[1]; Wang, Heli ^[2]; Turner, John ^[2]; More, Karren Leslie ^[1]; Young, David J ^[1]; Tortorelli, Peter F ^[1]; Payzant, E Andrew ^[1]; Walker, Larry R ^[1]

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1. ORNL
2. National Renewable Energy Laboratory (NREL)

Gas nitridation has shown excellent promise to form dense, electrically conductive and corrosion-resistant Cr-nitride surface layers on Ni-Cr base alloys for use as proton exchange membrane fuel cell (PEMFC) bipolar plates. Due to the high cost of nickel, Fe-base bipolar plate alloys are needed to meet the cost targets for many PEMFC applications. Unfortunately, nitridation of Fe-base stainless steel alloys typically leads to internal Cr-nitride precipitation rather than the desired protective surface nitride layer formation, due to the high permeability of nitrogen in these alloys. This paper reports the finding that it is possible to form a continuous, protective Cr-nitride (CrN and Cr{sub 2}N) surface layer through nitridation of Fe-base stainless steel alloys. The key to form a protective Cr-nitride surface layer was found to be the initial formation of oxide during nitridation, which prevented the internal nitridation typically observed for these alloys, and resulted in external Cr-nitride layer formation. The addition of V to the alloy, which resulted in the initial formation of V{sub 2}O{sub 3}-Cr{sub 2}O{sub 3}, was found to enhance this effect, by making the initially formed oxide more amenable to subsequent nitridation. The Cr-nitride surface layer formed on model V-modified Fe-27Cr alloys exhibited excellent corrosion resistance and low interfacial contact resistance under simulated PEMFC bipolar plate conditions.

• Research Organization: Oak Ridge National Laboratory (ORNL); High Temperature Materials Laboratory; Shared Research Equipment Collaborative Research Center
• Sponsoring Organization: EE USDOE - Office of Energy Efficiency and Renewable Energy (EE); SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 978784
• Journal Information: Journal of Power Sources, Journal Name: Journal of Power Sources Journal Issue: 1 Vol. 174; ISSN 0378-7753; ISSN JPSODZ
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
36 MATERIALS SCIENCE
ALLOYS
CORROSION RESISTANCE
NICKEL
NITRIDATION
NITRIDES
NITROGEN
OXIDES
PERMEABILITY
PLATES
PRECIPITATION
PROTON EXCHANGE MEMBRANE FUEL CELLS
STAINLESS STEELS
TARGETS