Preparation of corrosion-resistant and conductive trivalent Cr–C coatings on 304 stainless steel for use as bipolar plates in proton exchange membrane fuel cells by electrodeposition

Abstract

In this study, Cr–C-coated bipolar plates are produced by electroplating on the SS304 plates with a machined flow channel. The resulting plates were tested using potentiodynamic and potentiostatic measurements in simulated PEMFC environments, which show that the bipolar plate coated with Cr–C exhibited good anticorrosion performance. The corrosive current density of the Cr–C coating formed for a plating time of 10 min for 10 h exhibits a low stable value of 1.51 × 10−10 A/cm2 during the potentiostatic test in a 0.5 M H2SO4 + 2 ppm HF solution at 70 °C with an air purge, indicating that the Cr–C coating plated for 10 min is stable in a cathode environment. The interfacial contact resistance (ICR) of the bipolar plate with the Cr–C coating clearly improved, presenting an ICR of 19.52 mΩ cm2 at a pressure of 138 N/cm2. The results from scanning electron microscopy (SEM) and ICR before and after the corrosion tests indicate that the bipolar plate with the Cr–C coating is electrochemically stable. In this study, the maximum power density (212.41 mW/cm2) is obtained at a cell temperature of 80 °C and a gas flow rate of 300 standard cubic centimeters per minute (sccm) when Cr–C coated SS304 bipolar plates were used.