Fabrication of Mn-Co Spinel Coatings on Crofer 22 APU Stainless Steel by Electrophoretic Deposition for Interconnect Applications in Solid Oxide Fuel Cells

This study investigates the microstructure, oxidation kinetics, and electrical behavior of Mn-Co spinel coating for interconnect applications in solid oxide fuel cells. A relatively dense, uniform, and well-adherent Mn-Co (Mn1.5Co1.5O4) spinel coating with good oxidation resistance and stable conductivity was successfully prepared on the surface of Crofer 22 APU stainless steel using electrophoretic deposition followed by sintering at 1150 degrees C. During further thermal treatment at 800 degrees C, the chromium oxide (Cr2O3) sublayer formed at the substrate/coating interface during sintering showed a very slow growth, and no chromium penetration was detected in the Mn-Co coating. The oxidation kinetics of the Mn-Co-coated substrate obeyed the parabolic law with the a parabolic rate constant k(p) of 5.20x10(-15)g(2)/cm(4)/s, which was 1-2 orders of magnitude lower than that of the uncoated Crofer 22 APU stainless steel substrate. For oxidation (at 800 degrees C) times >= 50h, the area-specific resistance of the Mn-Co-coated Crofer 22 APU substrate became ~17m omega center dot cm(2) and was almost constant after further oxidation.