Oxide scale formation on alloy interconnects in CH4 fuels for solid oxide fuel cells

Abstract

Oxide scale formations in CH4-H2O atmospheres were investigated for different alloys for interconnects in solid oxide fuel cells (Fe-Cr and Ni-Cr alloys). Oxidation with anode gases (CH4, H 2O, CO, and CO2) caused a relatively thick oxide scale formation on the alloy surfaces even in the low oxygen partial pressures at 1073 K. The distribution of elements in the oxide scale and the growth rates of oxide scales were compared among the examined alloys by glow discharge optical emission spectrometry (GDOES). Mn-Fe and Mn-Ni spinels were formed on Fe-Cr alloys and Ni-Cr alloy surface, respectively. Oxide scale thickness grew with annealing time by a parabolic relationship, and the growth rates were in the orders of 10-6 -10-5 μm2s-1 at 1073 K. The electrical conductivity after forming oxide scales was different depending on the oxide scale phases and thickness, and was in the orders of 10 Scm-1 at 973 K.