Characterization of Fe–Cr Alloys for Reduced Operation Temperature SOFCs

Chemical stability of ferritic (Fe–Cr) alloy interconnect material was examined under anode gas atmospheres for use in solid oxide fuel cells (SOFCs). In H 2 –H 2 O and CH 4 –H 2 O atmospheres, oxide scale layers were formed on the alloy surface. The surface morphology of the alloy was varied with forming oxide scales at 1073 K for an extended annealing time. Secondary ion mass spectrometry (SIMS) was applied to analyze the distribution of major and minor elements as a function of depth. From surface to inner alloy, the following distribution was identified: Mn, Fe rich → Cr rich → Si rich → alloy bulk and Al 2 O 3 inner oxides. The parabolic growth rate constants of oxide scales ( k p ) were calculated for each atmosphere as follows: 3.76 × 10 –6 μm 2 s –1 for H 2 –H 2 O and 5.23  × 10 –6 μm 2 s –1 for CH 4 –H 2 O. The growth rate constants were similar between these two atmospheres.