ORALS

Ferritic stainless steels have been widely employed as solid oxide fuel cell (SOFC) interconnects owing to their low cost, coefficient of thermal expansion match with other SOFC components, and good oxidation resistance and acceptable electrical conductivity of Cr2O3. However, they are confronted with several problems during operation in SOFC cathode working condition such as the evaporation of Cr2O3 which results in cathode Cr-poisoning and subsequent degradation of cell performance [1-5]. Therefore, it is necessary to develop electrically conductive coating on them in order to block Cr2O3 evaporation. So far, CuFe2O4 spinel coating is a promising coating to improve the electrical conductivity of the surface oxide scale thermally formed on the steel. In present paper, CuFe alloy layer has been deposited on ferritic stainless steel (SUS 430) by magnetron sputtering method. The coated steels were evaluated in air at 800C corresponding to SOFC cathode environment. It was found that the coated steel initially experienced a large mass gain, followed by slight increase with time. The CuFe alloy layer was mainly converted into CuFe2O4 spinel layer beneath which a Cr-rich layer was grown from the steel substrate upon thermal exposure. The Cr-free outer layer not only suppressed Cr migration outward but also reduced the surface oxide scale area specific resistance (ASR) of the coated steel. <br />Keywords: (CuFe)3O4 coating, Solid oxide fuel cell interconnect, Oxidation, Electrical property

References:
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