Interactions between Metallic Interconnects and Ceramic Electrodes in SOFC Operating Environments: Air Side

Ferritic stainless steel (FSS) bipolar plates are widely used to interconnect individual cells in planar Solid Oxide Fuel Cell (SOFC) stacks. In this study, thin films of ceramic and cermet electrode materials, La0.8Sr0.2MnO3 (LSM) for the cathode and Ni-Y2O3/ZrO2 (Ni-YSZ) for the anode, were screen printed on Sanvik's Sanergy HT, a specialty FSS alloy (with and without Co or Co/Ce surface coatings). Samples were then placed in a test rig which allows simultaneous exposures to humidified (3% H2O) single (air/air) and dual atmospheres (air/H-2) at 800 degrees C for 100 hours. This research is focused on the FSS surface oxide layers and the phenomena governing materials interactions during realistic SOFC exposures that drive degradation. The surface oxide layer composition and morphology are heavily influenced by the dual atmosphere exposures and contact with electrode materials. For example, air-side surface oxide layers are generally thicker and contain more Fe than those formed in single-atmospheres, and surface oxide layer thickness and composition is altered in the presence of contacting electrodes in comparison with gas-only exposures. These and other recent data suggest that corrosion studies performed without relevant SOFC stack environments (e. g., air-only and without contacting electrodes) may not reveal all of the pertinent high-temperature behaviors. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.064211jes] All rights reserved.