Co-Ni Alloy Electrodeposition And Oxidation Resistance For SOFC SUS 430 Metallic Interconnect

The technology of solid oxide fuel cell (SOFC) has received aggressive attention as transferring device of new clean energy. In an attempt to reduce the oxidation of stainless steel interconnect and Cr evaporation, a protective coating layer composed of NiCo2O4 was deposited on the SUS 430 ferritic stainless steel substrate by the method of combined electrodeposition-oxidation method. The oxidation resistance and electrical conductivity of the NiCo2O4-coated stainless steel were measured at 800℃癈 in air. The phase composition and the microstructure/morphology of coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Energy Dispersive Spectrometer (EDS). Optimizing experiments were performed to decrease the micropores involved in the deposited layer prepared from electroplating. The results of oxidation weight gain showed that oxidation kinetics of coated and uncoated samples follow parabolic law respectively in 0-450h and 500-950h stages. The rate of oxidation weight gain of uncoated sample were 36.8×10-4mg2·cm-4 during 0-450h and 12.5×10-4mg2·cm-4 during 500-950h, while the oxidation weight gain rate of coated sample were 18.1×10-4mg2·cm-4 during 0-450h and 5.1×10-4mg2·cm-4 during 500-950h. The oxidation kinetics suggested that the oxidation weight gain rate of the coated sample was less than half of the uncoated sample one. Moreover, area specific resistance (ASR) measurement was tested by four-wire method on the uncoated and coated samples. Results showed that the ASR of uncoated sample was increased in 0-300h and maintained at 4.5Ω·cm2 in the range of 300-6O0h, and the ASR of coated sample was 0.9Ω·cm 2 which is lower than the uncoated sample. It suggests that the coated interconnect with NiCo2O4 coating layer prepared by electrodeposition-oxidation method possesses better oxidation resistance and higher conductivity than the untreated stainless steel.