Characterization of Porous Stainless Steel 430 for Low- and Intermediate-Temperature Solid Oxide Fuel Cell (SOFC) Substrates

Abstract

One approach to lower the cost of solid oxide fuel cells (SOFCs) is to lower the operating temperatures below 1073 K to allow the use of robust and comparatively inexpensive stainless steels not only for interconnects but also for SOFC support structures. The metal supports must be sufficiently porous to facilitate gas flow toward the reactive sites in the electrodes. Gas flow and electrical conductivity must remain adequate during any oxidation that occurs during operation. In order to identify microstructures most suitable for use as SOFC supports, a series of gas permeation and surface profilometry experiments was conducted to determine the permeability and surface roughness of porous steels (AISI 430) having different pore structures. The materials were also characterized by a variety of porosity measurement methods, each yielding complementary information on the three-dimensional structures. A combination of moderately low surface roughness and high gas permeability was found to represent a good combination of properties for metal-supported SOFC application.