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

Abstract

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.

Interface Design Development for High Durability of SOFC Interconnectors Using Electrodeposition Coating

“…As described elsewhere, 10,11,16 The ZMC electrodeposition coating on the 22Cr-Fe alloy such as the commodity ferritic stainless steel was sandwiched between Pt meshes and current was collected using the cathode material, La0.6Sr0.4Co0.2Fe0.8O3-δ as the conducting paste. Figure 3 presents the high temperature acceleration evaluation results of ZMC coated on the 22Cr-Fe alloy and ZnO coated on the SOFC special alloy, such as ZMG232L (Hitachi Metals, Ltd.) [17][18][19] installed 2012 model, respectively at (a) 950℃ and (b) 900℃. ZMC coated on the 22Cr-Fe alloy has significantly improved durability compared with the ZnO coated on the ZMG232L alloy.…”

“…These long-term durability tests were carried out by NEDO's project, "Basic study on rapid evaluation method of SOFC durability". [19][20][21][22][23][24][25][26][27][28] Osaka Gas and Kyocera have participated in the NEDO project to discuss the durability of SOFC. The cell stacks equipped with the electrodeposition coating on the commodity ferritic stainless steel showed almost the same deterioration rate as that of the ZnO coated on the ZMG232 L model, even if the current density was increased 1.5 to 1.8 times and fuel utilization was increased by five points.…”

Long-Term Oxidation Behavior of Fe-Cr Ferritic Alloy ZMG232L for SOFC Interconnects

“…ZMG232L is one of the developed Fe-Cr ferritic alloys especially for SOFC metallic interconnects. This alloy is a Fe-22mass%Cr ferritic alloy with a small addition of Zr and La and reduction of Si and Al, which has good oxidation resistance and good electrical conductivity at elevated temperature in the range of about 700-1000 o C required for SOFC interconnects (1)(2)(3). These metallic materials are usually machined or pressed into various shapes of interconnect parts.…”