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Surface modified stainless steels for PEM fuel cell bipolar plates

United States Patent

July 24, 2007
View the Complete Patent at the US Patent & Trademark Office
Oak Ridge National Laboratory - Visit the Partnerships Directorate Website
Improving Costs and Efficiency of PEM Fuel Cell Vehicles by Modifying the Surface of Stainless Steel Bipolar Plates
A nitridation treated stainless steel article (such as a bipolar plate for a proton exchange membrane fuel cell) having lower interfacial contact electrical resistance and better corrosion resistance than an untreated stainless steel article is disclosed. The treated stainless steel article has a surface layer including nitrogen-modified chromium-base oxide and precipitates of chromium nitride formed during nitridation wherein oxygen is present in the surface layer at a greater concentration than nitrogen. The surface layer may further include precipitates of titanium nitride and/or aluminum oxide. The surface layer in the treated article is chemically heterogeneous surface rather than a uniform or semi-uniform surface layer exclusively rich in chromium, titanium or aluminum. The precipitates of titanium nitride and/or aluminum oxide are formed by the nitriding treatment wherein titanium and/or aluminum in the stainless steel are segregated to the surface layer in forms that exhibit a low contact resistance and good corrosion resistance.
Brady; Michael P. (Oak Ridge, TN), Wang; Heli (Littleton, CO), Turner; John A. (Littleton, CO)
UT-Battelle, LLC (Oak Ridge, TN)
11/ 071,830
March 3, 2005
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH This invention was made with Government support under Contract No. DE-AC05-00OR22725 awarded to UT-Battelle, LLC, by the U.S. Department of Energy. The Government has certain rights in this invention.