Description: Grant applications are sought to identify and develop cost-effective processes for the application of high-quality yttria-stabilized zirconia (YSZ) coatings to SOFC interconnects in a mass production scenario.
High temperature (650C to 850C) planar SOFC stacks are comprised of alternating fuel and air chambers, which are sealed from each other by the SOFC cell and interconnect plates - typically ferritic stainless steel sheet (e.g., Allegheny Technologys SS441) stamped to form flow channels for the cathode-side air and anode-side fuel. Cell-to-interconnect and interconnect-to-interconnect seals are required for near-hermitic sealing glass-based seals are a common approach. Recent research within the SECA has focused on compliant glasses that remain vitreous over time in the SOFC stack operating environment, and are able to tolerate relative motion between the surfaces being sealed without the development of permanent leaks.
Certain glasses (e.g., SEM-COM Companys SCN-1, various compositions under investigation by Alfred University and Mo-Sci Corp., etc.) considered for this sealing application have broadly desirable properties (Tg, CTE, etc.), but have been found to chemically react with both bare stainless steel and alumina coatings applied to the stainless steel as a barrier layer, consequently forming phases that adversely affect the integrity of the seal. It has been shown that these glasses do not undergo similar reactions with YSZ thus its attractiveness as a barrier layer between the stainless steel substrate and the sealing glass.
Applicants to this topic shall focus on the cost-effective application of thin, dense, adherent zirconia coatings on select portions (e.g., the perimeter) of ferritic stainless steel or alumina-coated stainless steel SOFC interconnects. The Phase 1 work should emphasize proof-of-concept demonstration and production cost assessment. A prospective Phase II shall emphasize application to commercial scale interconnects along with rigorous verification of coating quality and adherence to the substrate.