Studies of Material Interaction After Long‐Term Stack Operation

Forschungszentrum Julich is routinely operating solid oxide fuel cells (SOFCs) in stacks of planar design. Anode-supported cells are used in combination with ferritic steel interconnects as standard components. The stacks are typically sealed with glass-ceramics. In order to examine the long-term interaction between the materials comprising these components, and the contact and protection layers, SOFC stacks with operation times of more than 6,000 h at 800 °C have been disassembled and microstructurally examined. The stack disassembling and examination procedures are outlined and results from optical and scanning electron microscopy are presented. Two interaction observations that are considered to affect stack performance are addressed in detail. The effects refer to the reaction of the glass-ceramic sealant with the ferritic steel interconnect and to Cr deposition at the cathode/electrolyte interface. Measures and strategies to diminish and/or to prevent unwanted long-term material interactions are discussed.