CrxN/Mn1.7Cu1.3 coating on ferritic stainless steel for solid oxide fuel cell interconnects

Abstract CrxN/Mn1.7Cu1.3 dual layer coating was prepared on SUS 430 steel via multi-arc ion plating and magnetron sputtering in sequence for use of solid oxide fuel cell (SOFC) interconnects. The coated steel was exposed to air at 800°C corresponding to the SOFC cathode environment to evaluate the oxidation behavior and electrical property of the surface scale. Results indicated that the Mn1.7Cu1.3 outer layer was thermally converted into Mn1.7Cu1.3O4 spinel outer layer and the CrxN inner layer was gradually oxidized to form a protective Cr2O3 layer at the interface of CrxN and Mn1.7Cu1.3O4. After the CrxN layer was completely oxidized, the surface scale mainly consisted of an outer Mn1.7Cu1.3O4 spinel layer and an inner Cr2O3 layer. Area specific resistance of the surface scale formed on CrxN/Mn1.7Cu1.3 coated steel after 15 weeks oxidation was 17.28 mΩ·cm2. The superior performance of the coated steel benefited from the combination of CrxN barrier layer and Mn1.7Cu1.3O4 spinel.