| 研究実績の概要 |
We succeeded in decreasing electrical resistance of the surface oxide layer of FeCrAl alloy. A relatively low electrical resistance was obtained when the LSCF-coated alloy was heat-treated at 700-800 oC in air. The surface oxide layer was changed to a complex structure consisting of gammaAl2O3 polycrystal and Sr3Al2O6 crystal growing outward in the same direction as a columnar structure. We also obtained the similar results with the case of LSCF using LSM, LNF or PrSM for the electrode materials. The electrical resistance of the Al2O3-based surface oxide layer on the alloy was decreased by the treatment. The activation energy for electron conduction, calculated from the electrical resistance, also suggests that the surface oxide became more conductive after the treatment. The microstructure of the oxide layer after the treatment was composed of columns growing outward in the same direction, containing small amounts of Sr, Ni, Fe, La, Mn, and Pr depending on the nature of the coating. The microstructure probably consists of gammaAl2O3 polycrystal and small amounts of Al compounds with these elements. The enhanced electrical conductivity seems to be caused by the arrangement of columns in the same direction, along with the generation of an electronic conduction path by the reaction of gammaAl2O3 with the coating elements. In the case of LNF coating, the surface oxide layer contains small amounts of Ni and Fe, and the electrical resistance and activation energy for electrical conduction were lower than those in the other cases, suggesting the formation of conductive materials.
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