Study on Electric Conductivity and Corrosion Resistance of Stainless Steel Bipolar Plates Coated with Cr2N
|School||Harbin Institute of Technology|
|Keywords||proton exchange membrane fuel cell(PEMFC) stainless steel bipolarplate Cr2N contact resistance corrosion resistance|
The stainless steel bipolar plates are areas of research focus on proton exchangemembrane fuel cell（PEMFC）. The well-proportioned Cr2N coatings were deposited on304stainless steel bipolar plates by magnetron sputtering. The effect of surfacemodification was evaluated by using methods of XRD、 AES、 SEM、 contactresistance testing and potentiodynamic polarization. Factors, such as the nitrogen flowrate, the deposition temperature, the deposition time, were checked to confirm theireffect on electric conductivity and corrosion resistance of the Cr2N coatings.Aftercomparing with the base metal and Cr coatings on SS304, the differences andrelationship among them are discussed.The XRD results and AES results showed that the coatings on SS304mainlycontain crystalling phase of Cr2N.The SEM results showed that stainless steel bipolarplates coated with chromium and nitrogen look more evenly than the base metal and Crcoatings on SS304. The contact resistance testing showed that stainless steel bipolarplates coated with chromium and nitrogen are good of electric conductivity, in the stackcompacting pressures of PEMFC, the contact resistance was70%lower than that of thebase metal. The potentiodynamic polarization showed that the stainless steel bipolarplates with Cr2N coating also showed improved corrosion resistance in the simulativeenvironment of PEMFC, the corrosion potential was enhanced by about300mV, thecorrosion current density was about1order of magnitude lower than that of the basemetal.The electric conductivity and corrosion resistance of the samples can be greatlyimproved by increasing the nitrogen flow rate, the deposition temperature and thedeposition time appropriately. The electric conductivity and corrosion resistance ofCr2N coatings on SS304are best while the nitrogen flow rate is1.5sccm, the depositiontemperature is300oC and the deposition time is60min.