Oxide Scales of Modified Fe-Cr Alloy (Low Si and Al Concentrations) in Reducing Atmospheres

Oxide scale formation was examined on the modified Fe-Cr alloys (Si and Al reduced concentrations) in H2-H2O or CH4-H2O atmospheres to simulate SOFC fuels. The formed oxide scales were characterized by surface and depth profile analyses. The oxide scale was composed of the following oxide phases from surface to inner oxide scale: Mn-Cr-(Fe) spinel layer, Cr2O3 layer, and Si-rich interface, and Al2O3 internal oxide. Although the scale formation mechanism is similar between modified and conventional alloys, the oxide scale growth rates were decreased in the modified Fe-Cr alloy. The electrical conductivity of oxidized Fe-Cr alloys was improved in the modified Fe-Cr alloy due to thinner oxide scale thickness and less distribution of insulating Si and Al internal oxides.