| Abstract: | The corrosion behavior and the electrical resistivity of the oxide scale that forms on alternative materials for bipolar plates in molten carbonate fuel cells (MCFCs) were investigated. Commercial stainless steels (SS) containing cobalt (Haynes 556) and manganese (Nitronic 30, Nitronic 50, and Nitronic 60) were tested under cathodic MCFC conditions Additionally, 316L SS coated with cobalt by thermal spraying was studied. Oxide‐scale resistivity measurements were coupled with observations of microstructural/compositional changes over time. All tested materials formed multilayered oxide scales. The composition of these phases was the key factor in determining the interfacial electrical resistivity. The high cobalt content of Haynes 556 (18 wt%) did not decrease its electrical resistivity or improve its corrosion resistance. Thus, Co‐containing stainless steels, such as Haynes 556, do not appear to be candidate bipolar plate materials for MCFCs. In contrast, the cobalt coating on 316L SS did lead to improved corrosion resistance. The Nitronic alloys formed Mn‐containing oxide scales, which appear to have a beneficial effect on lowering the resistivity of the oxide scale. The corrosion resistance of these Mn‐containing stainless steels was greater than that of 316L SS, the present bipolar plate material. |
