Work

Enhancing the corrosion resistance of ferritic stainless steel bipolar plates by forming an outer Cr2O3-rich passive film in simulated PEMFC cathodic environments

Year: 2025

Type: article

Abstract: In this study, a high Cr ferritic stainless steel was prepared by optimizing the alloy composition. It exhibited excellent corrosion resistance by forming an outer Cr 2 O 3 -rich layer passive film in the simulated PEMFC cathodic environment. The steel possessed a higher self-corrosion potential (−0.146 V MSE ) and lower self-corrosion current density (7.31×10 −7 A/cm 2 ) compared to AISI 316L, with a potentiostatic polarization current density at 0.23 V MSE of <0.46 μA/cm 2 . The steel underwent only minor pitting corrosion following potentiodynamic and potentiostatic polarization. Notably, the formation of a compact Cr 2 O 3 -rich outer layer was due to more Cr in the matrix promoting the diffusion of Cr into the passive film and the formation of Cr 2 O 3 , preventing the oxidation of internal Fe and Mo. Reducing the pitting corrosion of the steel due to the lower donor concentration and flat band potential inhibited aggressive F − attacks on the passive films. In addition, the minimal Mo 6+ content in the passive film implied that Mo possibly contributed less to the corrosion resistance of the steel, offering inspiration for optimizing Mo addition in high Cr ferritic stainless steels.

Source: Journal of Materials Research and Technology

DOI: 10.1016/j.jmrt.2025.09.223