Effects of Silver Addition on Properties and Performance of Plasma Sprayed La0.6Sr0.4Co0.2Fe0.8O3−δ Interconnect Layer

Abstract

Interconnect layers on stainless steel substrates (STS430) for solid oxide fuel cells (SOFC) were built up by atmospheric plasma spraying (APS) using spray dried La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) and blended LSCF/Ag composites. The microstructure and phase of each coating were analyzed using scanning electron microscopy (SEM) and x-ray diffraction (XRD) studies, respectively. Furthermore, bond strength, microhardness, performance in a thermal cycle test and in an oxidation test, and electrical conductivity were measured and compared. The coatings prepared from spray dried LSCF have higher porosity and more cracks within the splats and at intersplat boundaries. In contrast, the coatings prepared from LSCF/Ag had fewer cracks and less porosity due to the relatively high ductility of silver. After oxidation testing at 800 °C for 200 h, the weight change of the STS430 substrate and the LSCF and LSCF/Ag-coated alloys were found to be 0.06833, 0.01950, and 0.01656 mg/cm2, respectively. Also the electrical conductivity of LSCF and LSCF/Ag coatings were higher than that of STS430 by two orders.