Study Of Surface Modification Of Stainless Steel Bipolar Plates For Polymer Electrolyte Membrane Fuel Cells

Polymer Electrolyte Membrane Fuel Cell (PEMFC) is a clean appliance of energy conversion by which the chemical energy of fuel and oxidizer is converted into electricity directly. The appliance offered high power density, high energy conversion efficiency, low temperature operation and environment friendly, and was most promising for becoming the dynamic source of the electric vehicles. Most PEMFC are arranged into a chain structure by bipolar plates. Bipolar plates take up about 70～80% in quality and approximately 40～50% in cost of PEMFC. The too high cost is the main factor of that the PEMFC is difficult to achieve commercial application, and the power of unit weight and volume is lower at present. As an alternative material of traditional graphite bipolar plates, stainless steel has been widely researched. However, because of lower corrosion resistance and higher contact resistance, makes PEMFC cannot be commercial production on a large scale. This article studied SS304 bipolar plates in-depth in the aspect of the technology of surface modification, the element and organization of the films, the and conductivity.In order to enhancing the corrosion resistance and decreasing the contact resistance, our group do plasma osmolality Mo and plasma nitriding composite surface modification, and studied the corrosion behavior and ICR in simulating the environment of PEMFC after surface modifying. In the analysis of Mo-coated samples, the results show that the thickness of the Mo-coated depends mainly on the temperature and has little effect by the holding time; the main ingredients of the layer is Fe3Mo; the sample of heating 850℃and holding 4h showed the lowest corrosion current density. The ICR aspect, the sample of heating 830℃and holding 4h displayed highest conductivity. And in the analysis of nitriding layer samples, the result revealed that the thickness of various process parameters is about 20μm, and the main ingredients is Mo2N,and he sample of heating 600℃and holding 4h showed the lowest corrosion current density and that of heating 500℃and holding 2h displayed highest conductivity.