J. Oberste Berghaus, S. Bouaricha, J. G. Legoux, Industrial Materials Institute / -National Research Council Canada, Boucherville, QC, Canada; C. Moreau, National Research Council Canada (CNRC-NRC), Boucherville,, QC, Canada
SOFC half-cells, consisting of porous NiO-SDC (nickel--samarium doped ceria) anode sublayers and thin, nanostructured SDC electrolytes were fabricated. The layers were consecutively deposited onto metallic interconnects by suspension plasma spraying using an axial feed dc plasma torch. The liquid carrier employed in this approach allows for controlled injection of much finer particles than in conventional thermal spraying, leading to thin coatings with refined microstructure. The superior ionic conductivity of ceria-based ceramics over conventional SOFC materials has generated considerable interest in developing cost-effective techniques for producing those coatings.
Prior to spraying the assembled system, the coatings were produced individually for varying torch operating conditions and suspension feed rates. The resulting microstructures and phase compositions were analysed by SEM and XRD. Careful substrate temperature management during and after the spray process, in conjunction with high in-flight particle temperatures and velocities allowed for the production of dense, non-fractured electrolyte layers with thickness below 20µm. High porosities in the anode layers, which are required for effective gas permeation in the final cell, are attained. However, this porous microstructure generally comes at the expense of a non-continuous and rough surface, which constitutes a principal difficulty in the subsequent electrolyte deposition. The role of suspension feedstock properties on the surface structure is discussed. Selected electrochemical properties of the assembled half-cell are shown.
Summary: SOFC half-cells, consisting of porous NiO-SDC (nickel--samarium doped ceria) anode sublayers and thin, nanostructured SDC electrolytes were fabricated. The layers were consecutively deposited onto metallic interconnects by suspension plasma spraying using an axial feed dc plasma torch. The liquid carrier employed in this approach allows for controlled injection of much finer particles than in conventional thermal spraying, leading to thin coatings with refined microstructure. The superior ionic conductivity of ceria-based ceramics over conventional SOFC materials has generated considerable interest in developing cost-effective techniques for producing those coatings.
Prior to spraying the assembled system, the coatings were produced individually for varying torch operating conditions and suspension feed rates. The resulting microstructures and phase compositions were analysed by SEM and XRD. Careful substrate temperature management during and after the spray process, in conjunction with high in-flight particle temperatures and velocities allowed for the production of dense, non-fractured electrolyte layers with thickness below 20µm. High porosities in the anode layers, which are required for effective gas permeation in the final cell, are attained. However, this porous microstructure generally comes at the expense of a non-continuous and rough surface, which constitutes a principal difficulty in the subsequent electrolyte deposition. The role of suspension feedstock properties on the surface structure is discussed.
