Oxide Scale Formation on Alloy Interconnects in CH4 Fuels for Solid Oxide Fuel Cells

Abstract

Oxide scale formations in CH 4 -H 2 O 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 2 O, CO, and CO 2 ) 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 -10 -5 μm 2 s -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.