Oxidation and electrical behaviour of direct and pulse current electroplated cobalt coatings on Crofer22APU stainless steel interconnect

Abstract

Researches keep on to improve oxidation resistance and electrical conductivity of solid oxide fuel cell (SOFC) interconnects. In this work, Co coating was applied on Crofer22APU ferritic stainless steel interconnect by pulse current electrodeposition (PCE) method. The surface and cross-section of the samples were characterised by the SEM-EDX and XRD techniques. Investigations showed that pulse current resulted in decrease of grain size, roughness and porosity of Co deposits compared to the Co coating formed by the direct current electroplating (DCE) method. The steels were exposed to air at 800°C for 500 h and their oxidation rates were calculated. Oxidation rates were decreased for PCE-Co coated samples relative to for DCE-Co coated and uncoated samples. Electrical conductivity of the samples as a function of the temperature was also evaluated in air at 800°C. The PCE-Co coated Crofer22APU exhibited electrical conductivity as high as 54.64 S cm2 at 800°C.