Fabrication and Characterization of Solid Oxide Fuel Cell Interconnect Alloys
Church, Benjamin Cortright
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Metal alloy honeycomb structures were fabricated using a paste extrusion technique and characterized for potential application as interconnects in solid oxide fuel cells. Thermal expansion characteristics of Fe-Cr, Fe-Ni, Ni-Cr, Fe-Ni-Cr, and similar alloys containing an oxide dispersion were determined and compared with the thermal expansion behavior of yttria-stabilized zirconia (YSZ). A method was developed to calculate thermal expansion mismatch between two materials under a variety of heating and cooling conditions. It was shown that Fe 20 wt% Cr and Fe 47.5 wt% Ni alloys have low expansion mismatch with YSZ under a wide range of heating and cooling conditions. Oxidation experiments showed that Fe-Cr alloys have superior oxidation resistance in air at 700℃compared with Fe-Ni-Cr alloys with similar chromium contents. The inclusion of oxide dispersions (Y₂O₃ and CaO) into an alloy honeycomb was shown to improve oxidation resistance without affecting thermal expansion behavior. The honeycomb extrusion process provides a method by which experimental alloys can be produced and characterized rapidly to develop an alloy suitable for use as an interconnect in a solid oxide fuel cell.