Optimized Preparation And Electrochemical Properties Of AlCrN And TiAlCrN Films On Bipolar Plates Of PEMFC

The bipolar plate is one of the core components of the proton exchange membrane fuel cell(PEMFC).Traditional bipolar plates have limited production and application in large areas due to their high cost,high brittleness,and large volume.However,metal materials are easy to process,excellent in conductivity,and relatively low in cost,which provides a new way for the preparation and application of bipolar plates.However,the corrosion resistance and electrical conductivity of the metal bipolar plate in the PEMFC operating environment are still not ideal,which reduces the output performance of the fuel cell during operation.In this paper,multi-arc ion plating technology is used to prepare AlCrN and TiAlCrN metal nitride films on the surface on 316L ss to modify the surface.The optimized process parameters(nitrogen-argon flow ratio,bias voltage,Deposition time),and prepare AlCrN and TiA1CrN thin film modified layers based on optimized process parameters.Electrochemical performance test,interface contact resistance analysis and Mott-Schottky analysis at different potentials which were carried out in a simulated PEMFC environment.The research obtained the following results:(1)Using multi-arc ion plating technology to prepare AlCrN film modified layer on 316L stainless steel substrate,using scanning electron microscope(SEM),energy spectrometer(EDS)and X-ray diffractometer(XRD)to characterize the surface and cross-sectional shape of AlCrN film Appearance,phase structure,hardness and roughness of the film were measured using a hardness tester and a three-dimensional profiler.The optimized process parameters for preparing AlCrN thin film modified layer on 316L stainless steel are obtained:nitrogen-argon flow ratio is 0.22,bias voltage is-500V,and deposition time is 2h.(2)In order to improve the corrosion resistance of the film,AlCrN and TiAlCrN thin films were prepared under at above optimized process.The results of electrochemical test and interface contact resistance analysis show that in the simulated PEMFC environment,compared with 316L ss and AlCrN film,the modified layer of the TiAlCrN film has better corrosion resistance and exhibits better electrical conductivity.(3)In order to further improve the corrosion resistance of TiAlCrN film,four film forming potentials(0.1V,0.2V,0.3V,0.4)are selected according to the passivation interval on the dynamic polarization curve of the 316L stainless steel substrate,AlCrN and TiAlCrN film modified layers and perform potential polarization test,impedance spectroscopy(EIS)analysis and Mott-Schottky curve test on the passivation film formed for 1h after film formation at different film formation potentials.The results show that in the PEMFC environment,the corrosion current density of the passive film formed on the surface of the substrate and the film sample at the 0.3 V is lower than other potentials,so the modified bipolar plate at this voltage exhibits better corrosion resistance.