Porous metal substrate development for use in metal-supported solid oxide fuel cells

This work details an experimental approach for the development of porous stainless steel substrate for use in metal-supported solid oxide fuel cells (MSOFC). MSOFCs are considered the 3rd generation solid oxide fuel cell (SOFC), with expected benefits in decreased cost and increased durability.;The goal of this research focuses on a novel treatment of the metal substrate by rare earth or reactive element (RE) doping. RE nitrate precursors were mixed with stainless steel powders prior to substrate fabrication. Various dopant concentrations were systematically tested and their effects on the porosity, oxidation resistance, and electrical performance of the porous substrate were documented.;The metal powders and dopants chosen for this study were ferritic stainless steels (Fe30Cr and 430L) and reactive elements (La, Ce, and Y), respectively. A sintering study was carried out to optimize the porosity in the substrates with respect to open fuel channels and strength while establishing relationships between the porosity and dopant concentration. An oxidation study was performed by exposing the substrates in the cathode (air) and anode (H2/H 2O) environments at 800oC for 100 hours and recording the mass gains. The oxide scale formation was observed to change as a result of the dopant addition and exposure to various environments. It was found that RE addition could be beneficial to both the sinterability and the oxidation resistance of the substrates.;An electrical performance study was also conducted with select substrates by a typical 4-point probe area-specific resistance (ASR) method. ASR measurements were taken in both the cathode and anode environments over the temperatures of 500-800oC. The RE addition was found to have undesirable effects on electrical performance. However, long-term oxidation with continuous ASR testing over 450 hrs provided very favorable results for expected lifetimes before failure at 100 mO·cm2. The ASR increase proved to be several orders of magnitude lower than what was reported in the literature.;This work concludes that ferritic stainless steels are still a promising candidate for porous metal support. Future work on dense RE-containing coatings on porous stainless steel substrate is suggested to further enhance their performance stability.