PNNL

Abstract

Oxidation reaction of the ferritic stainless interconnects in a typical SOFC working environment is unavoidable and the thickness of the oxide scale will continue to grow with operating time, even with protective coatings. The interfacial strength of the various interfaces for the uncoated and coated ferritic interconnects is crucial to long term performance of SOFCs. In this paper, we employ an integrated experimental/modeling approach to quantify the interfacial strength and to further predict the life of Crofer 22 APU as SOFC interconnect under isothermal cooling condition. The life of Crofer 22 APU was predicted by comparing the predicted interfacial strength, interfacial stresses induced by the cooling process from the operating temperature to room temperature, together with the growth kinetics of oxide scale with and without spinel coating. It was found that the interfacial strength between the oxide scale and Crofer 22 APU substrate decreases with the growth of the oxide scale. The interfacial strength of the oxide scale and spinel coating is much higher than that of the oxide scale and Crofer 22 APU substrate. With the spinel coating, the predicted life of the Crofer 22 APU is significantly longer than that of the uncoated Crofer 22 APU.