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Effect of pH value on corrosion resistance and surface conductivity of plasma-nitrided 304L bipolar plate for PEMFC

Authors

  • Rujin Tian,

    Corresponding author
    1. College of Materials Science and Engineering, Dalian Jiaotong University, Dalian 116028, People's Republic of China
    • College of Materials Science and Engineering, Dalian Jiaotong University, Dalian 116028, People's Republic of China
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  • Juncai Sun

    1. Department of Materials Science and Engineering, Dalian Maritime University, Dalian 116026, People's Republic of China
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Abstract

Low temperature plasma nitriding is developed to meet the requirements for corrosion resistance and interfacial contact resistance (ICR) of stainless steel 304L as the bipolar plate for PEMFC. A dense and supersaturated-nitrogen nitrided layer has formed on the surface of the stainless steel 304L. Electrochemical behavior for the untreated and plasma-nitrided 304L was measured in H2SO4 (pH=1–5)+2 ppm F simulating PEMFC environment, and the ICR was evaluated before and after corrosion tests. The experimental results have shown that the ICR for the plasma nitrided 304L is lower than the requirement of U.S. DOE (<10 mΩ cm2 to 2010). Corrosion resistance and the ICR at the compaction force of 150–200 N cm−2 increase with increasing pH value for the untreated and plasma-nitrided 304L. The passive current densities for the untreated and plasma-nitrided 304L are all lower than 16 µA cm−2. The ICR between passive film and carbon paper are increased markedly because of passive film formed on the surface of both studied 304L. However, the passive current density and the ICR are lower for the plasma nitrided 304L than those for the untreated one at the given pH value, which results from the different composition of the stable passive film formed on the surface. The low temperature plasma nitriding provides a promising method for 304L using as bipolar plate for PEMFC. Further research is needed to evaluate the long-term stability of passive film and the performance of single fuel cell. Copyright © 2010 John Wiley & Sons, Ltd.

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