Characterization of CrAl coating on stainless steel bipolar plates for polymer electrolyte membrane fuel cells

CrAl alloy coating has advanced potential to improve corrosion inhibition, hydrophobicity, and electrical conductivity for metallic BPs. The feasibility of CrAl coating for surface modification of the BPs is thoroughly examined through comparative analysis with stainless steel 316L (SS316L). The coated specimen can reach high polarization resistance (Rp) and 93% inhibition efficiency (η) from Tafel plots. Based on the various surface properties of CrAl coating, corrosion resistance mechanisms for substitutional solid solution and nanograin structures containing hydrophobic and low surface free energy are proposed.