Performance of surface chromizing layer on 316L stainless steel for proton exchange membrane fuel cell bipolar plates

Abstract Stainless steels as proton exchange membrane fuel cell bipolar plates have received extensive attention in recent years. The pack chromizing layer was fabricated on 316L stainless steel to improve the corrosion resistance and electrical conductivity. The corrosion properties were investigated in 0.5 M H 2 SO 4 + 2 ppm HF solution at 70 °C purged with hydrogen gas and air. Higher electrochemical impedance and more stable passive film were obtained by chromizing the 316L stainless steel. Potentiodynamic polarization results showed the corrosion current densities were reduced to 0.264  μA cm −2 and 0.222  μA cm −2 in two simulated operating environments. In addition, the interfacial contact resistance was decreased to 1.4 mΩ⋅cm 2 under the compaction force of 140 N⋅cm −2 and maintained at low values after potentiostatic polarization for 4 h. The excellent corrosion and conductive performances could be attributed to the chromium carbides and high alloying element content in chromizing layer.