Fabrication of <scp>M</scp> n– <scp>C</scp> o Spinel Coatings on <scp>C</scp> rofer 22 <scp>APU</scp> Stainless Steel by Electrophoretic Deposition for Interconnect Applications in Solid Oxide Fuel Cells

Abstract

This study investigates the microstructure, oxidation kinetics, and electrical behavior of M n– C o spinel coating for interconnect applications in solid oxide fuel cells. A relatively dense, uniform, and well‐adherent M n– C o ( M n 1.5 C o 1.5 O 4 ) spinel coating with good oxidation resistance and stable conductivity was successfully prepared on the surface of C rofer 22 APU stainless steel using electrophoretic deposition followed by sintering at 1150°C. During further thermal treatment at 800°C, the chromium oxide ( C r 2 O 3 ) sublayer formed at the substrate/coating interface during sintering showed a very slow growth, and no chromium penetration was detected in the M n– C o coating. The oxidation kinetics of the M n– C o‐coated substrate obeyed the parabolic law with the a parabolic rate constant k p of 5.20 × 10 −15 g 2 /cm 4 /s, which was 1–2 orders of magnitude lower than that of the uncoated C rofer 22 APU stainless steel substrate. For oxidation (at 800°C) times ≥50 h, the area‐specific resistance of the M n– C o‐coated C rofer 22 APU substrate became ~17 mΩ·cm 2 and was almost constant after further oxidation.