Fabrication and Oxidation Behavior of the Cu–Fe Spinel Coating for SOFC Steel Interconnect Applications

Cu–Fe spinel has recently attracted considerable interest as a protective coating for solid oxide fuel cell steel interconnects. In this study, Cu–Fe spinel coatings were deposited on SUS 430 steel substrates via a coating route of the dip-coating process. Oxidation tests were investigated in laboratory air at up to 800 °C for five (5) 24 h (24 h) cycles up to 120 h. The area-specific resistance (ASR) of the samples was measured by a standard four-probe method. The experimental results indicated that the CuFe2O4 spinel powders with fine grain size were successfully synthesized from the sol–gel method. The oxidation kinetics of Cu–Fe spinel-coated steel obeyed a parabolic law, showing a parabolic rate constant of 1.38 × 10–14 g2 cm–4 s–1. The ASR value of the coated samples was about 11.2 mΩ cm2 at 800 °C. The Cu–Fe spinel coating improved both the high-temperature oxidation resistance and the electrical conductivity of the steel interconnects.