The preparation and properties of Mn–Co–O spinel coating for SOFC metallic interconnect

Abstract

To meet the performance requirements of solid oxide fuel cell (SOFC) metallic interconnect, the Mn–Co–O spinel coating is prepared on the surface of AISI430 by pack cementation method to reduce the growth kinetics of oxides and inhibit the outward diffusion of Cr. The microstructural characterization shows that a dense, uniform, defect-free spinel coating is successfully fabricated on the surface of AISI430. Under the simulated SOFC cathode environment, the weight gain of coated steel (0.608 mg cm−2) after oxidation at 800 °C for 800 h is significantly lower than that of uncoated (1.586 mg cm−2). In addition, the area specific resistance (ASR) of the coated steel oxidized for 500 h is 17.69 mΩ cm2, much smaller than that of the bare steel, indicating that the oxidation resistance and electrical conductivity of AISI430 are significantly improved by Mn–Co–O spinel coating. Cross-sectional observations of the Mn–Co–O spinel coating are conducted to assess the compatibility of substrate with the adjacent coating and its effectiveness in reducing the growth of the Cr2O3 layer.