Effect of chemical and heat treatment on the interfacial contact resistance and corrosion resistance of 446M ferritic stainless steel as a bipolar plate for polymer electrolyte membrane fuel cells

The bipolar plate is an important component of the polymer electrolyte membrane fuel cell (PEMFC) because it supplies the pathway of the electron flow between each unit cell. The ferritic stainless steel is considered a good candidate material for bipolar plate, but it is limited to use as a bipolar plate due to its corrosion problem and high interfacial contact resistance (ICR). To explore a cost-effective method of surface modification, various chemical and heat treatments are performed with 446M ferritic stainless steel to understand the effect of the surface modifications on the ICR and the corrosion resistance. The ICR and corrosion resistance of 446M stainless steel can be effectively controlled by a proper surface modification with combined treatment of immersion in the acidic solution, followed by heat treatment. The combined chemical and heat treatment not only improves the corrosion resistance but also reduces the ICR value.