Evaluation of electrical resistance activation energy for cobalt-coated interconnects

Abstract

The oxidation resistance and the electrical conductivity of solid oxide fuel cells (SOFCs) interconnects can be improved with a protective/conductive coating layer. In this study AISI 441 ferritic stainless steel is coated by pack cementation method in a Co-base pack mixture. The microstructure of the samples is then examined by SEM and EDS, and phases are identified by XRD. In order to evaluate the area specific resistance (ASR) isothermal oxidation is applied at 800ºC for 300 h. Also oxidation at different temperatures (500-1000ºC) is carried out to evaluate electrical resistance activation energy. Results show the formation of cobaltspinels during oxidation caused to the reduction of electrical resistance (ASR for coated substrates: 12.3 mΩ cm² and for uncoated substrates: 40.1 mΩ cm²). Also electrical resistance activation energy for coated samples is lower compared to uncoated ones.