Influence of preoxidation on high temperature behavior of NiFe2 coated SOFC interconnect steel

NiFe₂O₄ spinel coating is promising for solid oxide fuel cell (SOFC) steel interconnects application. In this work, NiFe₂ alloy coating was sputtered on bare steel and preoxidized steel (100 h in air at 800 °C), respectively, followed by exposing in air at 800 °C for up to 15 weeks in order to investigate the influence of steel preoxidation on high temperature behaviors of the coated steels. The results indicated that an outer NiFe₂O₄ spinel layer atop an inner Cr₂O₃ layer formed on the coated samples after oxidation. The preoxidation enhanced the oxidation resistance of the coated sample and reduced Cr out-migration to NiFe₂O₄ spinel layer. After 15 weeks, the area specific resistance (ASR) of surface scale on the coated preoxidized steel was much lower than that on the coated bare steel. The mechanisms of the preoxidation influence on oxidation behavior and surface scale electrical property of the coated steels were discussed.