Magnesium-Manganese Spinel Coatings for Solid Oxide Fuel Cell Interconnects

Magnesium and manganese were electrodeposited on stainless steel 430 and oxidized in air at 800 degrees C to form a spinel coating. Electrical conductivity of MgMn2O4 spinel was determined to be similar to 2 S/cm at 800 degrees C. An under layer of copper aided uniform manganese deposition and uniform spinel formation. Copper in the spinel also increased conductivity (Cu0.7Mg0.3Mn2O4 similar to 60 S/cm at 800 degrees C). The ternary Cu-Mg-Mn system has a wide spinel stability region compared to binary systems. CuMn2O4 spinel without magnesium has higher conductivity (similar to 100 S/cm at 800 degrees C) but this coating tended to bubble and detach from the substrate. The bubbling effect was reduced when magnesium was codeposited.