Study On Modification And Properties Of Surface Carbon-Based Film In Metallic Bipolar Plates Of Fuel Cell

Fuel cells are considered as a new generation of energy carriers due to their high efficiency,fast start-up,wide operating temperature range,and environment friendliness.As one of the core components of fuel cells,bipolar plates need to meet criteria such as low gas permeability,good corrosion resistance,high surface conductivity and excellent formability.Metal bipolar plates are regarded as the ideal material for bipolar plates because of their small size and easy processing,which greatly improve the power density of the cell stack,as well as their good corrosion resistance and electrical conductivity.However,in the acidic（p H=3）,high temperature（70°C～80°C）and high humidity environment of the proton exchange membrane fuel cell（PEMFC）,the metal is prone to corrosion,and the metal ions produced will poison the catalytic layer and other components,moreover,the passivation layer produced will reduce the interfacial conductivity of the bipolar plate.Therefore,surface modification of the metal bipolar plate becomes an important way to solve the problem.In order to investigate the electrical conductivity and corrosion resistance of amorphous carbon-based films modified metal bipolar plates,amorphous carbon-based films are prepared on the surface of metal bipolar plates using coating technology in this paper.The research contents and results are as follows:（1）Amorphous carbon-based thin films were prepared on the surface of TA1 using unbalanced magnetron sputtering technique,and gas flow channels were prepared on the surface of the coated pole plate using the stamping and forming process.The structure and properties of the films were systematically investigated before and after forming.The results show that the amorphous carbon film is still closely adhered to the substrate after mechanical processing,and the film does not peel off significantly.The corrosion current density of the specimen in the long-time constant potential polarization test at 0.6 V_{Ag/Ag Cl} was 1.4×10^-7A/cm²,and the interfacial contact resistance increased by 1.7 mΩ·cm² after corrosion.The analysis of the film corrosion process reveals that the main body of the coated specimen corrosion resistance undergoes a transformation from carbon film to metal interlayer oxide with the corrosion process.（2）Amorphous carbon-based thin films were prepared on the surface of TA1 by unbalanced magnetron sputtering technique,and gas flow channels were prepared on the surface of the coated pole plate by stamping process.The structure and properties of the films were systematically studied before and after stamping.The results show that the amorphous carbon-based thin film is still closely adhered to the substrate after mechanical processing,and the film is not significantly peeled off;The corrosion current density in the long time constant potential polarization test under 0.6 V_{Ag/Ag Cl} is 1.4×10^-7 A/cm².The interface contact resistance increases by 1.7 mΩ·cm² after corrosion.The analysis of the film corrosion process reveals that,as the corrosion process proceeds,the corrosion resistance of the coated specimen of the main body from the carbon film to the metal interlayer oxide.（3）The performance of amorphous carbon-based films prepared by multi-arc ion plating on TA1 surface was optimized by regulating the thickness of the surface amorphous carbon layer and the metal interlayer.The results showed that the increase of the amorphous carbon layer thickness effectively increased the passivation potential of the film,a thinner amorphous carbon layer could achieve a lower corrosion current density,the regulation of the carbon film thickness could effectively control the reaction process,and the organization and composition of the amorphous carbon-based films with different metal interlayer thicknesses did not change significantly.