Effect of slurry-coated LaSrMnO3 on the electrical property of Fe–Cr alloy for metallic interconnect of SOFC

The effect of (La0.85Sr0.15)0.9MnO3 (LSM) coating layer on the electric properties of the Fe–16Cr alloy (SUS430) and Fecralloy® was examined in air. The LSM layer was coated on the Fe–Cr alloys by slurry-dipping process and was sintered at 1200 °C. When the LSM-coated SUS 430 was sintered in Ar atmosphere with H2, the phase separation of the LSM coating layer was observed, which increased the area specific resistance. The decomposed LSM phase changed to a stable phase with increasing the holding time at 750 °C in air. When the LSM-coated SUS 430 was heat-treated in air at 1000 °C after the sintering, the stable LSM-coated SUS 430 showed a low area-specific resistance (ASR) and maintained almost a constant value for 2600 h. The area specific resistances of the LSM-coated Fe–Cr alloys depend on the interfacial oxide layer formed between LSM and alloys. The LSM-coated Fecralloy® showed a much larger area-specific resistance due to the formation of Al-rich mixed interfacial oxide. It is concluded that the LSM-coated Fecralloy® made by sintering process is not adequate for metallic interconnect.