CuFe2O4/CuO coating for solid oxide fuel cell steel interconnects

CuFe0.8 (Fe:Cu = 0.8:1, atomic ratio) alloy layer is fabricated on both bare and pre-oxidized SUS 430 steels by direct current magnetron sputtering, followed by exposing at 800 °C in air to obtain a protective coating for solid oxide fuel cell (SOFC) steel interconnects. The CuFe0.8 alloy layer is thermally converted to CuFe2O4/CuO coating, which effectively suppresses the out-migration of Cr. Pre-oxidation treatment not only initially accelerates the formation of CuFe2O4/CuO coating but also further inhibits the Cr and Fe outward diffusion. Suppressing outward diffusion of Cr could improve electrical property of oxide scale and decrease the risk of cathode Cr-poisoning. Blocking out-diffusion of Fe is beneficial to stabilize the CuO layer. After 2520 h oxidation, the scale ASR at 800 °C is 66.9 mΩ cm2 for coated bare steel, 43.4 mΩ cm2 for the coated pre-oxidized steel.