• Oum, Melissa
• Steinberger-Wilckens, Robert
• Hong, Jong-Eun

Abstract

Ferritic stainless steel interconnects are critical components in Solid Oxide Fuel Cells (SOFCs), which electrically connect the cells and prevent gases from mixing. At high temperatures and in the presence of air, oxidation of the metallic interconnects leads to the formation of a passivation scale of chromium oxide. The growing thickness of the scale increases the electrical contact resistance of the interconnects and the formation of volatile chromium species lead to chromium poisoning in the cathode. It is therefore critically<br/>important for the estimation of the lifetime of SOFCs to investigate these degradation mechanisms which affect the long-term output cell voltage.<br/>This study examines the high temperature oxidation behavior in conventional ferritic stainless steel (FeCr) interconnects, using thermodynamic and kinetic modelling approaches. The first stage of the study involves designing a coupled one-dimensional thermodynamic-kinetic oxidation and diffusion model. This model is based on the simultaneous thermodynamic assessment of oxidation reactions and calculation of scale growth kinetics, using a finite difference numerical method.<br/>The expected results allow to predict the composition profile in the alloy, as well as the thickness of the oxide layer formed as a function of oxidation time. This model will serve as a basis for life-time prediction of a manganese and cobalt spinel protective layer coated FeCr interconnect in the second stage of the study.

Topics

• impedance spectroscopy
• stainless steel
• chromium
• cobalt
• Manganese
• one-dimensional