| The main part of current energy is fossil-fuel belongs to non-renewable resources. However, the consumption of these resources and serious environmental pollution make the sustainable development of the human society problems face a serious challenge. Proton Exchange membrane fuel cells (PEMFC) is fresh energy source which has high efficiency and cleanliness. It solves the increasing contradictions between economic development and environment pollution. Bipolar plate is very important component which distribute the fuel gas and oxygen to the anode and cathode and also provide the electrical contact between adjacent cells in PEMFC. Metal bipolar plate has been concerned by its better mechanical machining than traditional graphite bipolar plate. Compared to metal, graphite is expensive to machining gas channels and its brittleness is another hurdle. But metal bipolar plate will be affected by corrosion in PEMFC mild acidic environment, which reduce battery performance. People usually prepare coatings on the surface of metal bipolar plate to improve its corrosion resistance. However coating increase cost and the defect is inevitable, film coating hinder the application of metal bipolar plate.In this thesis, new Fe-Cr-Ni alloy melted in our previous work was investigated and undergone surface chemical modification. The performance of Fe-Cr-Ni bipolar plate after various chemical treatment was measured through0.5mol/L H2SO4+2ppm HF solution to simulate an aggressive PEMFC environment, Also, ICR between carbon paper (diffusion layer) and sample was evaluated by Wang’s contact resistance testing method to study the influence of the electric conductivity after kinds of chemical treatment. The testing technology of FESEM, AFM, and XPS were developed to analyze the surface layer with different modification methods and obtained its information of morphology and composition. The information of the passive film was used to analyze the reason that different surface modification processes resulted in different surface conductivity.The research shows that corrosion resistance and electrical conductivity of new Fe-Cr-Ni alloy through six times electrochemical oxidation treatment are greatly improved. The performance achieves the requirements of application. However, the single cell has short lifetime, it suggests simple process do not meet the needs of long time working. X acid treatment-low temperature permeability nitrogen process improve corrosion resistance, but still need to improve in a conductive aspects. X acid treatment-electrochemical oxidation-low temperature nitriding process increased the contact resistance, indicating that this process form thick passivation, but the passivation which is not dense makes the corrosion resistance of the sample is bad. X acid treatment-low temperature nitriding-electrochemical oxidation process can reduce the contact resistance greatly, and in the180N-cm-2pressure approach and less than graphite. The corrosion current density is a little higher than X acid treatment-low temperature nitriding process, but still less than16μA·cm-2, completely achieves the requirements of application. |
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