Preparation on New Ni-Cr-Fe Alloy as Bipolar Plates for PEMFC
|School||Wuhan University of Technology|
|Course||Materials Processing Engineering|
|Keywords||Metal bipolar plates Surface chemical treatment Nanoscale spikes Longitudinal conductivity Vacuum induction melting|
The bipolar plate is one of the key components of proton exchange membrane fuel cell, separated by oxidizing and reducing agents, separated from the main fuel cell electric heap the role of each battery and collection of current transportation. The cost and performance of the proton exchange membrane fuel cell bipolar plate process to promote the proton exchange membrane fuel cell industry has a great impact. In order to solve the defects of the high cost of conventional graphite bipolar plates, difficult to process, in order to overcome the current cost of the main study, the metal bipolar plate coating, the coating hidden obstacle, this thesis melting synthesis of novel Ni-Cr-Fe alloy, and explore A surface chemical treatment method for surface modification of the alloy bipolar plate, from the theoretical analysis of the feasibility of this approach, and a single battery test. This exploration based on specific experiments before and after the process of this method, surface modification microstructure analysis, and its corrosion resistance and surface contact resistance. Pure Ni, Cr, Fe, as the raw material, changes to the content ratio of the plurality of groups of Ni-Cr-Fe alloy using a vacuum induction melting furnace, to study the surface chemical treatment of the reagents and processing conditions, and by 0.5mol / L H2SO4 2ppm HF solution to simulate the proton exchange membrane fuel cell etching solution environment to evaluate the corrosion resistance and electrical conductivity both filter out the best Ni, Cr, Fe ratio and the best surface chemical treatment means, and finally this kind of double plate with graphite bipolar plates, coated metal plates of single cell performance test. By polarization curves and the contact resistance of the graphite carbon paper to characterize and optimize the process. The results show that the best overall performance of the components Ni, Cr, Fe mass ratios were 32%, 30%, 38% of the metallic bipolar plate as a substrate, the chemical treatment of the surface of the X acid 8min as surface modification means to improve alloys and has the highest electrical conductivity and the strongest anti-corrosive new Ni-Cr-Fe alloy bipolar plate performance can achieve the design standards of the PEMFC single cell performance test results are quite satisfactory. The valence state of the elements of the surface layer by XPS analysis by AES depth analysis of its surface layer film structure by using FESEM and AFM study their morphology, combined with its contact resistance variation seen, X processing the 8min new Ni-Cr-Fe alloy formed on a surface layer of nanoscale tip under the electric field, the tip is easier to gather more charge conductivity significantly increased because nanoscale tip discharge, electron transfer to the efficiency of the diffusion layer (graphitic carbon paper) improved.