Estimation of Shearing and Peeling Thermal Stress of Spinel Coated Metallic Interconnects of Solid Oxide Fuel Cells

Abstract

Abstract Interconnects are used in solid oxide fuel cells (SOFCs) for connecting the fuel cell stacks. These interconnect are coated with spinel oxides to prevent the formation of a native scale oxide layer under high heat flux conditions. Generally, the SOFCs are subjected to thermal shock during their operation. At the interfaces of these coating, shear stresses and peeling stresses were induced due to a mismatch between the thermal expansion coefficient of coating and native scale thickness. These stresses peel off the coating layers which affect the interconnect performance. In this paper, the effect of varying native scale thickness at two different coating thicknesses on the shearing stress and peeling stress of the interconnects is analytically calculated along the two different interconnect thicknesses. The oxidation kinetics of spinel-coated SOFCs interconnects with the analytical equations relating native scale thickness with the time of SOFCs operation were reported. As per our analysis, we concluded that these stresses majorly depend on the thickness and the mechanical properties of the interconnects, native scale and a coating layer.