a b s t r a c t a r t i c l e i n f o (SSZ) were applied by dip-coating in aqueous suspensions. Electrolyte powders had been attrition-milled to decrease their particle size and densification temperature. The quantity of polyacrylic acid (PAA) as dispersant was optimised by ζ-potential measurements. The densification behaviour was studied by dilatometry and SEM-imaging. A sintering temperature of 1250°C was found to densify GDC whereas SSZlayers remained slightly porous.
Nd1.95NiO4+δ (NNO) cathode supported microtubular cells were fabricated and characterized. This material presents superior oxygen transport properties in comparison with other commonly used cathode materials. The supporting tubes were fabricated by cold isostatic pressing (CIP) using NNO powders and corn starch as pore former. The electrolyte (GDC, gadolinia doped ceria based) was deposited by wet powder spraying (WPS) on top of pre-sintered tubes and then co-sintered. Finally, a NiO/GDC suspension was dip-coated and sintered as the anode. Optimization of the cell fabrication process is shown. Power densities at 750 ºC of ∼40 mWcm -2 at 0.5V were achieved. These results are the first electrochemical measurements reported using NNO cathode-supported microtubular cells. Further developments of the fabrication process are needed for this type of cells in order to compete with the standard microtubular solid oxide fuel cells (SOFC).
Tubes of diameter <5mm of a nickelate cathode material of composition Nd1.95NiO4 were prepared by cold-isostatic pressing (CIP) and extrusion. These tubes are intended as cathode support structure for micro-tubular SOFCs at reduced working temperatures around 700{degree sign}C. The characteristics of these tubes - porosity, pore size, geometric dimensions and surface roughness - were measured by various techniques such as mercury intrusion, SEM-Imaging and with an in-house built diffusion setup. Diffusion measurements yielded average pore sizes of 0.12 μm for CIP-ed tubes and 0.22 μm for extruded tubes. Estimation of the loss due to oxygen diffusion has shown that the wall thickness of CIP-ed tubes must be reduced prior to coating processes in order to limit oxygen concentration overpotential loss during operation.
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