Long-term Stability of MnCo Spinel Coatings Prepared by Electrophoretic Deposition at High Temperatures
Spinel coatings Mn1.5Co1.5O4 on steels SUS430 and Crofer22H were prepared via electro-phoretic deposition,aiming to improve their high-temperature oxidation resistance and electrical conductiv-ity as SOFC interconnector.Afterwards,their oxidation behavior at 700-800℃ and electrical conductivity after oxidation were characterized by means of intermittent weighing method,X-ray diffraction(XRD),scanning electron microscope(SEM)and 4-wire electrical resistance tester(ASR).The result showed that relatively dense coatings may be acquired by two-step sintering.The oxidation rate of Mn1.5Co1.5O4/SUS430 oxidized at 800℃ for 1000 h is about(1-3)× 10-14 g2·cm-4·s-1,and the oxidation rate constant decreases by 1-2 orders of magnitude as the temperature decreases.Mn1.5Co1.5O4/SUS430 formed a thinner Cr-contain-ing oxide scale due to its own low Cr content,at the same time,the Fe diffused outward from the sub-strate steel during the oxidation process to further promote the coating densification.Ultimately,after high temperature oxidation,the Mn1.5Co1.5O4/SUS430 showed ASR values lower than those of the Mn1.5Co1.5O4/Crofer22H.
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