Formation and performances of spinel reaction layers on Co-40Mn coatings under an oxygen pressure of 105 Pa for solid oxide fuel cell interconnect application

Abstract

Because of good high temperature conductivity (Mn,Co)3O4 is a promising oxide coating for solid oxide fuel cell interconnect. High-temperature oxidation of Co-Mn alloys at 750 °C and 850 °C at 105 Pa oxygen reveals that formation of a continuous (Co,Mn)3O4 spinel layer significantly decreases oxidation rate constant but not the same for the discontinuous spinel layer. Co-40Mn fine grain alloy coatings are prepared by high-energy micro-arc alloying process (HEMAA). Microstructures and compositions after preparation and oxidation were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). When pre-oxidized under an oxygen pressure of 105 Pa at 850 °C for 10 h, Co-40Mn coatings are transformed into the external oxide which is mainly composed of (Co,Mn)3O4 and Mn3O4. The results disclose Cr outward transport from the stainless steel is significantly suppressed by the as-prepared (Co,Mn)3O4 oxide coatings, when coatings oxidized at 800 °C for 100 h in wet air. The composited spinel coatings have excellent high temperature oxidation resistance and electrical performance.