Preformed Oxide Scale Chemistry and Its Influence on Local Metal Loss During Dual Atmosphere Corrosion
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Stainless steels, commonly used for the fabrication of cell stack and balance-of-plant (BoP) components in intermediate temperature solid oxide electrochemical systems, are subject to simultaneous exposure of a bi-polar oxidizing (cathodic) and reducing (anodic) atmosphere. This exposure condition, often termed “dual atmosphere”, has been shown to induce anomalous, localized corrosion through selective and accelerated oxidation of the base alloy. Ferritic stainless steels are seen as candidate materials for interconnects within electrochemically active cell stacks because of their matching thermal expansion coefficient with contacting ceramic cell components (electrolyte/cathode/anode). The corrosion behavior of a selected ferritic stainless steel has been experimentally examined under dual atmosphere conditions. In comparison, different treatments of the steel were carried out to preform an oxide scale and observed further oxidation behavior in dual atmosphere compared to as-received steel. Scale compositions and morphologies after pretreatment and post- dual atmosphere exposure will be mentioned and discussed. Hypotheses regarding the role of dual atmosphere in enhanced oxidation and the role of pre-treatments for steels used as interconnects will be discussed.
KeywordsDual atmosphere Pre-treatment Oxidation Corrosion Ferritic stainless steel
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