Cyclic oxidation of Mn–Co spinel coated SUS 430 alloy in the cathodic atmosphere of solid oxide fuel cells

In order to improve oxidation resistance and long-term stability of the metallic interconnects and prevent the cathode of solid oxide fuel cells (SOFCs) from Cr-poisoning, an effective, relatively dense and well adherent Mn–Co spinel protection coating with a nominal composition of MnCo2O4 is applied onto the surfaces of the SUS 430 ferritic stainless steel by a cost-effective sol–gel process. The long-term thermally cyclic oxidation kinetics and oxide scale structures as well as the composition of the coated SUS 430 alloy are investigated. The Mn–Co spinel protection layer demonstrates an excellent structural and thermomechanical stability, and effectively acts as a mass barrier to the outward diffusion of cations, especially Cr, and a lowered parabolic rate constant of kp = 1.951 × 10−15 g2 cm−4 s−1 is obtained.