PERFORMANCE OF METALLIC INTERCONNECT IN SOLID-OXIDE FUEL CELLS

摘要

Over the last decade, there has been a push to decrease the operating temperature of solid-oxide fuel cells (SOFCs) to slow down degradation mechanisms of metallic interconnects. Metals suitable for this application must exhibit coefficients of thermal expansion (CTE) comparable to those of ceramic components. On the air (cathode) side, the interconnect must also possess good corrosion resistance to high-temperature oxidation. To meet these requirements, many heat-resistant ferritic alloys containing sufficient chromium (Cr) are considered the choice of cathode interconnect due to their relatively low CTEs and satisfactory oxidation resistance. In general, the corrosion resistance of ferritic alloys under consideration is attributed to their ability to form a protective chromium oxide (Cr_2O_3) scale on exposure to high-temperature environments. Once formed, the Cr_2O_3 scale adheres strongly to the metal surface and becomes essentially impermeable to corrosive gases. Consequently, this scale can act as a diffusion barrier for oxygen on the cathode interconnect, protecting the alloy from rapid oxidation attack during operation.