Research on Spinel-Based Oxide Coating Material on Alloy Interconnect for Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFC) are one of the promising high-energy conversion systems that produce electricity and heat. Research and development on SOFC are now coming to the reduction of the operating temperature from 1273 to around 973 K. Therefore, metal alloys can be applied to interconnect for SOFC. However, oxide scale formation occurs on the surface under the operating atmosphere and causes decreasing the electrical conductivity. Some spinel-based oxides are investigated as a protective layer preventing the alloy surface from further oxidation. In order to clarify the optimum synthesis conditions of the spinel-based oxides, (Fe1-xZnx)Mn2O4 (0.0≦x≦1.0) were prepared by solid-state reaction and the influences of the conditions on the XRD patterns were discussed. Sample of the ZnMn2O4 (x=1.0) fired at 1373 K for 10 hours was confirmed to be the single phase. However, in case of the FeMn2O4 (x=0.0), the peaks of MnO and Mn2O3 were detected in the XRD pattern. The impurities increased when the FeMn2O4 was fired at higher temperature in the range of 1473 K. The thermal tolerance seems to be lower than that of the ZnMn2O4. In addition, the electrical conductivities of them were measured with four probe method under dry-air atmosphere from 673 to 1273 K