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

Abstract 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.