Effect of bias voltage on high-temperature oxidation resistance and electrical properties of Mn-Co coating with metal interconnects for solid oxide fuel cell

Abstract This study investigated the effects of bias voltage on the microstructure, high-temperature oxidation resistance, electrical conductivity, element diffusion, and barrier of chromium poisoning cathode of Mn-Co coating on the surface of SOFCs metal interconnect SUS441 ferritic stainless steel. A series of Mn-Co coatings were prepared by magnetron sputtering technique at different bias voltages (−10, −50, −90 V) and oxidized at high temperatures for 175 h at 850 °C in an air environment. The results showed that the surface of each coating before oxidation exhibited a cauliflower-like morphology, with the crystallinity of the coating increasing with higher bias voltage. After high-temperature oxidation, especially the Mn-Co coatings prepared at −90 V bias, a dense and stable MnCo2O₄ spinel structure was formed, which is crucial in inhibiting the growth of the Cr2O3 oxide layer. In addition, the coating also exhibits excellent electrical conductivity (Ea=0.35eV), good high-temperature oxidation resistance (1.182 mg/cm2), and a stronger ability to prevent the diffusion of Cr elements.