Chromium interlayer amorphous carbon film for 304 stainless steel bipolar plate of proton exchange membrane fuel cell

Excellent electrical conductivity and corrosion resistance make the graphite-like carbon film an ideal surface modification for metal bipolar plates, but the pinhole inside amorphous carbon (a-C) causes pitting corrosion of the substrate. Chromium interlayer amorphous carbon (Cr/a-C) was prepared for 304SS bipolar plate. The interlock structure between the Cr interlayer and a-C film prevented corrosive liquid from reaching the substrate. The Cr/a-C film was prepared on 304SS by direct current magnetron sputtering. The hydrophobic property, interfacial contact resistance (ICR), and corrosion resistance of Cr/a-C 304SS were investigatedand compared, with those of bare 304SS and a-C 304SS. In addition, the performance and stability of the assembled single fuel cell were analyzed. Results show that the contact angle with water of Cr/a-C 304SS is 89.5. The ICR of Cr/a-C 304SS under compaction force of 150 N/cm(2) is 16.65 m Omega cm(2), which is better than that of a-C 304SS. The SEM and TEM results reveal the interlock structure between the Cr interlayer and a-C film. This structure results in excellent corrosion resistance, corrosion potential of -0.32 V, and corrosion current density of 0.894 mu A cm(-2) in the simulated proton exchange membrane fuel cell (PEMFC). Single cell tests show that the peak power density of Cr/a-C 304SS PEMFC is 1.123 W cm(-2), with no observed degradation during 12 h lifetime tests. Thus, the Cr/aC film is an ideal protective layer for 304SS bipolar plates of PEMFC. (C) 2016 Elsevier B.V. All rights reserved.