The influence of pre-treatment on the oxidation behavior of Co coated SOFC interconnects

Cobalt coatings are candidates to inhibit high-temperature surface oxidation of solid oxide fuel cell (SOFC) stainless steel (SS) interconnects. This study investigates the influence of surface pre-treatment on the oxidation behavior of cobalt coated SS441. Metallic cobalt was deposited via DC magnetron sputtering on SS that had been pre-oxidized for 0, 10, and 100 hrs in 800 degrees C air. The samples were analyzed using FE-SEWEDX, XRD, and XPS before and after 10 and 100 h of oxidation. Significant differences in oxidation behavior were observed. For example, the pre-oxidized samples exhibited combined coating/oxide scales that contained much less Fe and were significantly thinner compared to samples that were not preoxidized. The presence of a continuous chromium oxide layer (from pre-oxidation) may inhibit iron transport from the substrate and thus reduce the thickness of the oxide scale. Possible mechanisms for the observed oxidation behavior are presented and discussed. Copyright (C) 2010, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.