Effect of reactive elements on oxidation behaviour of Fe–22Cr–0.5Mn ferritic stainless steel for a solid oxide fuel cell interconnect

Ferritic stainless steel has become a promising material for metallic interconnects for solid oxide fuel cells (SOFCs) operating in an intermediate temperature range (650–800 °C). Ferritic stainless steels containing reactive elements (REs) such as Crofer22APU and ZMG232 have been developed for SOFC interconnects. Nevertheless, the effectiveness of REs on the growth kinetics of the chromia-rich scale that forms on the ferritic stainless steels is not yet well understood. The current study focuses on the investigation of the effect of REs such as Y, Ce and La on the oxidation behaviour and scale properties of Fe–22Cr–0.5Mn stainless steel. The results show that Y is the most effective reactive element for reducing the scale growth kinetics and area-specific resistance of the chromia scale which forms on this stainless steel. The growth kinetics of the chromia-rich scale can be effectively reduced by the dominant segregation of Y at the interface between the oxide scale and alloy substrate, and by the formation of a thin SiO2 and MnO layer underneath the Cr2O3-rich oxide.