Corrosive Behavior and Interfacial Conductivity of Stampable A-C Film on Titanium Bipolar Plate in Proton Exchange Membrane Fuel Cells

Titanium bipolar plates coated with amorphous carbon films are considered to combine good electrical con-ductivity and corrosion resistance in proton exchange membrane fuel cells. However, there is a lack of research on the post-forming surface properties of coated bipolar plates. In this study, a-C film was deposited on the surface of titanium foil using unbalanced magnetron sputtering technique. The film displayed strong adhesion and no obvious post-formation peeling. The chemical composition, interfacial conductivity, surface and cross-sectional morphology and corrosion resistance of the deposited films were all thoroughly examined. The re-sults showed that the specimens exhibited good corrosion resistance and significantly improved interfacial conductivity under a simulated fuel cell cathode environment. In comparison to titanium substrate, the corrosion current density and contact resistance of the specimens were orders of magnitude lower, and the excellent stability of the a-C films led to almost no change in contact resistance following corrosion. Additionally, a-C film corrosion under cathodic condition was investigated. These results offer strong justification for the practical use of stampable a-C film on titanium bipolar plates in PEMFCs.