Mica-based Composite Compressive Seals for SOFC

Abstract

One of the critical challenges facing planar solid oxide fuel cell (SOFC) technology is the need for reliable sealing technology. Seals are required for long-term stability and integrity in the high temperature SOFC environment during normal and transient operations. Several different approaches for sealing SOFC stacks are under development, including glass or glass-ceramic seals, metallic brazes, and compressive seals. Compressive seals potentially offer a significant and unique advantage over the other approaches by providing a means of mechanically ''de-coupling'' adjacent stack components, thereby minimizing the need for closely matching the coefficients of thermal expansion (CTE) of the various SOFC stack components. In an attempt to help the SOFC industry overcome sealing challenges, PNNL is developing mica-based hybrid compressive seals which exhibit leak rates 2 to 3 orders of magnitude lower than obtained with simple mica gasket seals.