A promising NiCo2O4 protective coating for metallic interconnects of solid oxide fuel cells

The NiCo2O4 spinel coating is applied onto the surfaces of the SUS 430 ferritic stainless steel by the sol–gel process; and the coated alloy, together with the uncoated as a comparison, is cyclically oxidized in air at 800 °C for 200 h. The oxidation behavior and oxide scale microstructure as well as the electrical property are characterized. The results indicate that the oxidation resistance is significantly enhanced by the protective coating with a parabolic rate constant of 8.1 × 10−15 g2 cm−4 s−1, while the electrical conductivity is considerably improved due to inhibited growth of resistive Cr2O3 and the formation of conductive spinel phases in the oxide scale.