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Investigation of formation of γN phase layer and its effect on surface properties of 316 L stainless steel bipolar plate for proton exchange membrane fuel cell
Chunpeng Liu a, Chuanwei Li a , **, Zhenhua Ye a, Xinyu Zhang a, Jin Zhang a, Jianfeng Gua,b,*
ainstitute of Materials Modification and Modelling, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
bShanghai Key Laboratory of Materials Laser Processing and Modification, Shanghai Jiao Tong University, Shanghai 200240, China
Abstract:
In this paper, the surface microstructure and properties of plasma-nitrided 316 L stainless steel bipolar plate with a thickness of 0.1 mm were investigated. The surface microstructure of the nitrided sample was characterized by SEM, TEM, XRD and XPS. After plasma nitriding, a nitrogen-expand austenite (γ N plasma-nitrided sample surface. In γ N phase) layer was formed on the phase layer, a large amount of stacking fault was formed and the super lattice lattice was found owing to serious lattice distortion under high plasma nitriding condition. The hydro phobic property, conductivity and corrosion resistance of the nitrided samples were obviously improved compared with the untreated sample. Under long time or high temperature condition, although a thicker γ N phase layer was formed, the surface corrosion resistance of the plasma-nitrided samples became worse. Under high hydrogen condition, the plasma-nitrided sample surface exhibited the good corrosion resistance and elec trical conductivity. The interfacial contact resistance of the sample was only 8 mΩ (≤20 mΩ), and the corrosion resistance of the sample was 90 times higher than that of the untreated sample. The influence of phase composition and microstructure in nitriding layer as well as surface morphology on surface properties of plasma- nitrided sample were analyzed in detail. This work proves that plasma nitriding technology has great advantages in improving surface properties of the bipolar plate.
Investigation of formation of γN phase layer and its effect on surface properties of 316 L stainless steel bipolar plate for proton exchange membrane fuel cell.pdf
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