High temperature oxidation/corrosion behavior of metals and alloys under a hydrogen gradient

Metallic interconnects in SOFC stacks, perform in challenging environment, as they are simultaneously exposed to a reducing environment (e.g. hydrogen, reformate) on one side and an oxidizing environment (e.g. air) on the other side at elevated temperatures. To understand the oxidation/corrosion behavior of metals and alloys under the dual exposures and assess their suitability, selected metals and alloys, including nickel, Fe–Cr and Ni–Cr based chromia forming alloys, alumina forming Fecralloy ® , were investigated. It was found that the oxidation/corrosion behavior of metals and alloys in the presence of dual environment can be significantly different in terms of scale structure and/or chemistry from their exposure in a single oxidizing or reducing atmosphere. The anomalous oxidization/corrosion is attributed to the presence of hydrogen diffusion flux from the fuel side to the air side under the influence of a hydrogen gradient across the metallic substrates.