Abstract
Thermal (gas) nitridation of stainless steel alloys can yield low interfacial contact resistance (ICR), electrically conductive and corrosion-resistant nitride containing surface layers (Cr2N, CrN, TiN, V2N, VN, etc.) of interest for fuel cells, batteries, and sensors. This paper presents results of scale-up studies to determine the feasibility of extending the nitridation approach to thin 0.1 mm stainless steel alloy foils for proton exchange membrane fuel cell (PEMFC) bipolar plates. Developmental Fe-20Cr-4V alloy and type 2205 stainless steel foils were treated by pre-oxidation and nitridation to form low-ICR, corrosion-resistant surfaces. As-treated Fe-20Cr-4V foil exhibited target (low) ICR values, whereas 2205 foil suffered from run-to-run variation in ICR values, ranging up to 2× the target value. Pre-oxidized and nitrided surface structure examination revealed surface-through-layer-thickness V-nitride particles for the treated Fe-20Cr-4V, but near continuous chromia for treated 2205 stainless steel, which was linked to the variation in ICR values. Promising corrosion resistance was observed under simulated aggressive PEMFC anode- and cathode-side bipolar plate conditions for both materials, although ICR values were observed to increase. The implications of these findings for stamped bipolar plate foils are discussed.
Original language | English |
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Pages (from-to) | 5610-5618 |
Number of pages | 9 |
Journal | Journal of Power Sources |
Volume | 195 |
Issue number | 17 |
DOIs | |
State | Published - Sep 1 2010 |
Funding
The authors thank D.F. Wilson, T.J. Toops, B.A. Pint, and D.P. Stinton for reviewing this manuscript. The authors also thank L.R. Walker for microprobe analysis, D.W. Coffey for STEM specimen preparation, G.W. Garner for performing the nitridation exposures, and J.M. Rakowski of ATI Allegheny Ludlum for the Fe–20Cr–4V and 2205 stainless steel foils. Funding from the U.S. Department of Energy's Hydrogen, Fuel Cells, and Infrastructure Program is gratefully acknowledged. Research supported by ORNL's SHaRE User Facility, which is sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, the U.S. Department of Energy. B. McCarthy thanks the ORAU HERE program for a summer internship at ORNL. ORNL is managed by UT-Battelle, LLC for the US DOE under contract DE-AC05-00OR22725. Notice: This submission was sponsored by a contractor of the United States Government under contract DE-AC05-00OR22725 with the United States Department of Energy. The United States Government retains, and the publisher, by accepting this submission for publication, acknowledges that the United States Government retains, a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this submission, or allow others to do so, for United States Government purposes.
Funders | Funder number |
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Office of Basic Energy Sciences | |
Scientific User Facilities Division | |
United States Department of Energy | |
U.S. Department of Energy | DE-AC05-00OR22725 |
Oak Ridge National Laboratory |
Keywords
- Corrosion resistance
- Durability
- Metallic bipolar plates
- Nitride
- Polymer electrolyte/proton exchange membrane (PEM) fuel cells