Corrosion resistance and contact resistance properties of Cr-doped amorphous carbon films deposited under different carbon target current on the 316L stainless steel bipolar plate for PEMFC

Abstract

Cr doped amorphous carbon is deposited under different carbon targets on 316L stainless steel by magnetron sputtering technology. By adjusting the current value of the carbon target, amorphous carbon coatings with different phase structures are obtained. The carbon target currents are set to 1A, 3A, 5A and 7A, and Cr targets are set at 0.3A as the doping atoms. With the improvement of currents, the coating's structure shifting from the Cr–C and Cr phase (C-1A) to the amorphous carbon, Cr and Cr–C phase (C-3A, C-5A and C-7A). Potentiodynamic polarization tests show that C-3A and C-5A samples have better corrosion resistance. At 1.1V (vs. SHE) potentiostatic trials, carbon target current at 5A shows the lowest current density, 9.8 × 10−8 A/cm2. Interfacial contact resistance decreased firstly and then increased with the improving current density. C-5A has the lowest values, 3.2 mΩ∙ cm2.