Evaluation of Selected Interconnect Alloys at Versa Power Systems: Laboratory Screening and In-stack Testing

Versa Power Systems (VPS) develops planar SOFC operating at intermediate temperature around 750{degree sign}C. At that temperature, metallic interconnects are suitable due to their low cost, availability, matching thermal expansion and easy manufacturing. However their oxidation as a function of time remains one of the main contributors to fuel cell degradation and life performance. At VPS a complete laboratory characterization was developed for a fundamental understanding of the oxidation of those alloys. However, in-stack testing has been an ideal vehicle for in-situ steel comparison in the fuel cell environment. Interconnects are made with different alloys and assembled together in a single stack to be tested. A detailed post-test analysis of numerous tested stacks, including at least two different alloys, has provided valuable information on the relation between steel composition, oxidation and performance. Testing included long holds at various temperatures and a number of transients.