Dense spinel MnCo2O4 film coating by aerosol deposition on ferritic steel alloy for protection of chromic evaporation and low-conductivity scale formation

Conducting ceramic layers with a spinel structure of MnCo2O4 and a thickness of ~3 μm were deposited on ferritic stainless steel (SS) by aerosol deposition (AD), for use as an oxidation-resistant coating layer on the metallic interconnects of a solid oxide fuel cell (SOFC). The microstructural changes in the interface between the MnCo2O4 and SS were analyzed, as were the subsequent electrical conductivity changes at an SOFC operating temperature of 800 °C in air. The coated spinel layers were dense without pores or cracks, and maintained good adhesion even after oxidation at 800 °C for 1,000 h in air atmosphere. Close observation of the interface between the coated spinel oxide and SS substrate indicated the presence of ~1-μm thick, Cr-rich scale formation; however no MnCrCoO4 or MnCr2O4 spinel phase was detected. The area specific resistance (ASR) of the MnCo2O4-coated alloy after heat treatment at 800 °C for 1,000 h was 13.4 mΩ cm2.