Fe–N–C surface treatment as method for enhancing spontaneous passivation of low Ni and Cr stainless steel

Passivation through cathodic modification has largely remained a theoretical concept due to the reliance on noble metals. In this study, we successfully achieved passivation in AISI 409 L steel, an alloy with reduced Ni and Cr content, by applying a cost-effective Fe–N–C oxygen reduction catalyst coating in a 0.5 M H 2 S O 4 solution. The passive state was maintained over 24-hour immersion tests, and corrosion resistance improved significantly compared to the active state. Electrochemical and analytical evaluations confirmed a significant enhancement in corrosion resistance, as demonstrated by a ∼99.94 % reduction in passive current density from polarization curve analysis and a ∼99.98 % reduction in corrosion rate from ICP measurements. These results highlight the potential of using non-noble metal catalysts to improve surface corrosion resistance in low-cost stainless steels or materials with reduced corrosion resistance due to mechanical property optimization.