Characterization of Plasma Sprayed Mn1.0Co1.9Fe0.1O4 Coating on Crofer 22 APU Interconnect for Solid Oxide Fuel Cell Application

Abstract

Atmospheric plasma sprayed Mn<inf>1.0</inf>Co<inf>1.9</inf>Fe<inf>0.1</inf>O<inf>4</inf> (MCF) coating is regarded as one of the excellent materials in mitigating Cr-evaporation in Crofer 22 APU ferritic steel during high-temperature operation in solid oxide fuel cell (SOFC) conditions. In this study, MCF-coated Crofer steel has been characterized by examining the cross-section of as-sprayed coating. A network of micro-cracks and globular pores was seen in the cross-section analysis. The porosity of as-sprayed MCF coating was 10.93 ± 1.323%. XRD data revealed α-Fe as the major phase in as-received Crofer steel and CoO as the major phase in MCF coating. Micro-hardness measurements of MCF coating was 163.5 ± 1.5 HV<inf>0.1N</inf>. The measured values revealed strong metallic interlocking between the coating and substrate. Four-probe method employed on MCF coating showed a decrease in resistance as a function of temperature, indicating an increase in electrical conductivity. The spinel coating on Crofer steel was found to be beneficial for SOFC operation. © 2022, The Indian Institute of Metals - IIM.