Interpretation of Corrosion Mechanism on Cathode Side Separator for Molten Carbonate Fuel Cell

摘要

This study was carried out for the purpose of investigating the corrOSIOn behavior and mechanism on a separator for a molten carbonate fuel cell under both the electrolyte and cathode side environment. A SUS310S austenitic stainless steel was used as the separator material. Corrosion proceeded via three steps; a formation step of corrosion product in which rapid corrosion take places until a stable corrosion product is formed after the beginning of corrosion; secondly, a protection step against corrosion until breakaway occurs after the formation step of the stable corrosion product; finally, an advance step of corrosion after breakaway. From the standpoint of the behavior of the elements in the separator, Fe, Cr and Ni were formed richly in the region of the corrosion product, in the region of corrosion protection, and at the Cr-depleted zone respectively. With respect to the corrosion mechanism, direct reaction with electrolyte and elements of the separator at the cathode side was the main corrosionmechanism, and the final corrosion product was LiFe02. The corrosion rate of the separator at the cathode side was rapid at the initial stage of corrosion.However, the corrosion rate was decreased due to the resistant effect of chromiumoxide.