Interfacial Shear Strength of Oxide Scale and SS 441 Substrate

Abstract

Recent developments on decreasing the operating temperature for solid oxide fuel cells (SOFCs) have enabled the use of high-temperature ferritic alloys as interconnect materials. Oxide scale will inevitably grow on the ferritic interconnects in a high-temperature oxidation environment of SOFCs. The growth of the oxide scale induces growth stresses in the scale layer and on the scale/substrate interface. These growth stresses combined with the thermal stresses induced after stacking cooling by the thermal expansion coefficient mismatch between the oxide scale and the substrate may lead to scale delamination/buckling and eventual spallation, which may lead to serious cell performance degradation. Hence, the interfacial adhesion strength between the oxide scale and the substrate is crucial to the reliability and durability of the metallic interconnect in SOFC operating environments. In this article, we applied an integrated experimental/modeling methodology to quantify the interfacial adhesion strength between the oxide scale and the SS 441 metallic interconnect. The predicted interfacial strength is discussed in detail.