Oxidation Behavior and Chromium Evaporation From Fe and Ni Base Alloys Under SOFC Systems Operation Conditions

Fe and Ni base alloys serve as materials of choice for the fabrication of stack and balance of plant components in solid oxide fuel cell power systems. The oxidation behavior of select Fe and Ni base alloys has been investigated, and chromium evaporation rates have been experimentally measured at 850°C in 3% humidified air exposure conditions. Changes in the oxide morphology and chemistry from the alloys representing chromia former (602CA), alumina former (H214), and mixed chromia and alumina scale formers (AFA25) at 900°C and 1100°C during exposure to humidified air have been studied and are presented. It is found that the rate of Cr evaporation from the alloys decreases in the order of 602CA followed by Haynes 214 and AFA25 at 850°C during exposure to humidified air. Surface and cross-sectional scale morphologies and chemistry have been examined, and variations in the Cr evaporation behavior of different alloys are discussed based on the reaction thermodynamics.