Microstructure, Oxidation Resistance, and Electrical Conductivity of CeO2-Doped Co-Fe-Ni Spinel Coatings on SUS 430 SOFC Interconnects
摘要
To enhance the oxidation resistance and electrical conductivity of solid oxide fuel cell (SOFCs) interconnects at high temperatures, CeO2-doped Co-Fe-Ni spinel coatings were prepared on SUS 430 steel through electroplating followed by pre-oxidation. The microstructures of the CeO2-doped Co-Fe-Ni spinel coatings were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS). The oxidation behavior and area specific resistance (ASR) of the CeO2-doped and undoped Co-Fe-Ni spinel coatings were investigated by cyclic oxidation experiments and the four-probe method, respectively. The results showed that the Co-Fe-Ni spinel coatings exhibited a dense structure and smooth surface when the CeO2 doping content was 10 g/L. Furthermore, the Cr-rich layer thickness of the CeO2-doped Co-Fe-Ni coating was thinner than the Co-Fe-Ni coating after oxidation in air at 800°C for 168 h, which was only 1.3 μm, which indicated that CeO2 doping effectively suppressed the outward diffusion of Cr. The oxidation rate constant (kp) of the CeO2-doped Co-Fe-Ni spinel coating was 2.0095 × 10−14 g2 cm−4 s−1, and the ASR value was stabilized at 14.6 mΩ cm2 after oxidation in air at 800°C for 168 h. This study demonstrated that CeO2 doping effectively improved the oxidation resistance and electrical conductivity of Co-Fe-Ni spinel-coated steels at high temperatures.