The passivation behaviour of copper-containing high-performance ferritic stainless steels in the cathode environment of polymer electrolyte membrane fuel cells

The passivation behaviour of copper-containing high-performance ferritic stainless steels in the cathode environment of polymer electrolyte membrane fuel cells was investigated using electrochemical tests and XPS surface analyses. The addition of copper to the alloy deteriorated the corrosion resistance at a passive region of 0.6 VSCE. With an increase of the copper content, the passivity of the alloy degraded due to an increase of the formation of Cr-containing inclusions, and a decrease of the Cr oxide and hydroxide in the passive film.

► A greater content of Cu in the alloy enhanced the active corrosion resistance. ► A greater content of Cu in the alloy decreased the passive corrosion resistance. ► A greater content of Cu in the alloy increased the number and area of inclusions. ► A greater content of Cu in the alloy decreased the Cr oxide and hydroxide in film. ► The passivity of Cu added alloy degraded due to the inclusions and the Cr species.