LSCo/LSCF Composite Material As Cr-Gettering Materials for Solid Oxide Fuel Cells

Abstract

Chromium poisoning has been identified as the main cause for degradation when metallic parts are used in SOFC. Early mitigation was focused on protective coatings. Recently, Cr-gettering materials have been explored either in upstream or on-cell applications. In previous work, we have shown LSCF can readily trap Cr volatile species at elevated temperatures. In this work we propose LSCo/LSCF composite as a candidate for on-cell Cr-gettering materials. LSCo will be mixed with base material of LSCF4628 at 10, 20, and 30 v%, because of its high electrical conductivity. Mixed powders will be pressed and sintered as pellets and rods. Sintered rods will be tested for CTE. Measured CTE will be compared with predictions from rule of mixtures. XRD will be used to characterize crystalline phases to assess chemical compatibility. The sintered pellets will also be measured electrical conductivity at 650-900oC in the as-sintered and 1000h aged state. Selected sample microstructures will be characterized by SEM/EDS and EPMA. Bulk strength will also be determined by diametral compression. Finally, candidate LSCo/LSCF4628 will be tested as on-cell in a generic stack test fixture at 800oC for 1000h with Cr volatile species, along with baseline cell. Post-mortem microstructure analysis will be conducted to assess the validity of on-cell gettering.