Thermally Nitrided Stainless Steels for Polymer Electrolyte Membrane Fuel Cell Bipolar Plates: Part 1 Model Ni-50Cr and Austenitic 349TM alloys

Journal Article · Thu Jan 01 04:00:00 EST 2004 · Journal of Power Sources

DOI:https://doi.org/10.1016/j.jpowsour.2004.06.067· OSTI ID:1003129

Wang, Heli ^[1]; Brady, Michael P ^[2]; Turner, John ^[1]

---

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

Thermal nitridation of a model Ni-50Cr alloy at 1100 C for 2 h in pure nitrogen resulted in the formation of a continuous, protective CrN/Cr{sub 2}N surface layer with a low interfacial contact resistance. Application of similar nitridation parameters to an austenitic stainless steel, 349{sup TM}, however, resulted in a discontinuous mixture of discrete CrN, Cr{sub 2}N and (Cr,Fe){sub 2}N{sub 1-x} (x = 0--0.5) phase surface particles overlying an exposed {gamma} austenite-based matrix, rather than a continuous nitride surface layer. The interfacial contact resistance of the 349{sup TM} was reduced significantly by the nitridation treatment. However, in the simulated PEMFC environments (1 M H{sub 2}SO{sub 4} + 2 ppm F{sup -} solutions at 70 C sparged with either hydrogen or air), very high corrosion currents were observed under both anodic and cathodic conditions. This poor behavior was linked to the lack of continuity of the Cr-rich nitride surface formed on 349{sup TM} Issues regarding achieving continuous, protective Cr-nitride surface layers on stainless steel alloys are discussed.

• Research Organization: Oak Ridge National Laboratory (ORNL); Shared Research Equipment Collaborative Research Center
• Sponsoring Organization: EE USDOE - Office of Energy Efficiency and Renewable Energy (EE)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1003129
• Journal Information: Journal of Power Sources, Journal Name: Journal of Power Sources Journal Issue: 1/2 Vol. 138; ISSN 0378-7753
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
30 DIRECT ENERGY CONVERSION
36 MATERIALS SCIENCE
ALLOYS
AUSTENITIC STEELS
CORROSION
ELECTROLYTES
FUEL CELLS
HYDROGEN
LAYERS
MEMBRANES
MIXTURES
NICKEL BASE ALLOYS
NITRIDATION
NITRIDES
NITROGEN
PARTICLES
POLYMERS
PROTON EXCHANGE MEMBRANE FUEL CELLS
SOLUTIONS
STAINLESS STEELS
SURFACES
TEMPERATURE RANGE 1000-4000 K