Fabrication and high-temperature corrosion of sol-gel Mn/Co oxide spinel coating on AISI 430

MnCo oxide spinels have received recent interest as surface coatings on ferritic stainless steel (FSS) interconnects in solid oxide fuel cell (SOFC) stacks, where they provide relatively stable electrical conductivity and reduced Cr volatility compared to uncoated FSS interconnects. In this study, sol-gel deposited MnCo surface coatings on FSS, with post-deposition treatments, were investigated in laboratory air at up to 750 °C for up to 750 h. The protective coating formed and evolved isomorphic crystallites, (Mn,Co,Fe,Cr)3O4, following fifteen (15) fifty hour (50 h) cycles in air up to 750 °C. Relative to the surface oxide on the uncoated FSS, the coating was dense, crack-free and exhibited substantially lower area specific resistance (ASR). Coating preparation and behaviors during oxidizing exposures are presented and discussed in context of developing improved SOFC material systems.