Corrosion and Interdiffusion in a Ni/Fe–Cr–Al Couple Used for the Anode Side of Multi-Layered Interconnector for SOFC Applications

Abstract

Under operating conditions in solid-oxide fuel cells (SOFC), metallic-interconnect plates form oxide scales (e.g., Cr₂O₃, Al₂O₃) on their surface, which have an electrically insulating effect and increase the contact resistance between the interconnect and the electrodes. In order to ensure high electrical conductivity between the electrodes and the interconnects, the formation of oxide scales on the interconnect surface must be prevented or minimized. The present work shows possibilities for improved contacts at the anodic side in solid-oxide fuel cells by plating an Fe–Cr–5.7Al interconnect with a Ni foil. Contact-resistance measurements and microscopic studies show the electrical behavior and corrosion of materials used at 800°C under an Ar/4 vol.% H₂/3 vol.% H₂O atmosphere. The results reveal that the interconnects coated with nickel exhibit low aging rates in the investigations performed and are thus suitable for use on the anode side.