Comparison of corrosion behavior between coarse grained and nanocrystalline Ni-Fe alloys in chloride solutions and proton exchange membrane fuel cell environment by EIS, XPS and Raman spectra techniques

The corrosion resistance of coarse grained and nanocrystalline Ni-Fe alloys in chloride solutions and proton exchange membrane fuel cell environment was investigated. The nanocrystalline Ni-Fe alloys were obtained by electrodeposition, while coarse grained Ni-Fe alloys were obtained by annealing. The results from electrochemical tests showed that coarse grained Ni-Fe alloys had higher corrosion resistance than nanocrystalline samples in NaCl solution due to more compact passive films formed on the surface of coarse grained Ni-Fe alloys. In addition, Raman spectra test showed that many nanocrystalline boundaries in electrodeposited Ni-Fe alloys promoted the diffusion of nickel, which resulted in the formation of more nickel oxides and nickel hydroxides. However, the electrochemical study showed that coarse grained sample had lower corrosion resistance than nanocrystalline one in a typical proton exchange membrane fuel cell environment. The present study showed that nanocrystalline Ni-Fe alloys were more suitable for the bipolar plates in proton exchange membrane fuel cell environment. (C) 2016 Elsevier Ltd. All rights reserved.