Protective Coatings for Ferritic Stainless Steel Interconnect Materials in High Temperature Solid Oxide Electrolyser Atmospheres

Stainless steel interconnect materials used in solid oxide fuel cells and electrolysers need to be coated to improve oxidation resistance and to mitigate Cr-vaporization. This work aimed to explore the optimal steel/coating combinations suitable for use in reversible solid oxide stacks and evaluated (Co,Mn)3O4 spinel, LaFeO3 perovskite, Ce/Co and Y-based coatings, on AISI441 and Crofer 22 APU steels. The coatings were evaluated based on measurements of mass gain and oxide scale thickness after exposure at 700 and 800 °C to fuel side (90 vol.% H2O/10 vol.% H2) and air/oxygen side (pure O2) atmospheres. In pure O2, the most efficient coatings for limiting oxide scale formation and Cr evaporation, compared to the bare steel, were (Co,Mn)3O4 and CeCo on Crofer 22 APU. In 90 vol.% H2O/10 vol.% H2, the Y-based coating showed the largest improvement in oxidation resistance.