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2110 |
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Tuesday, May 04, 2010, Olivia Room 4:00 PM Power Engineering and SOFC 2 |
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Deposition of NiO and YSZ composite anode and YSZ electrolyte by suspension plasma spray |
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Youliang Wang* / Industrial Materials Institute, National Research Council Canada, Canada Jean-Gabriel Legoux / Industrial Materials Institute, National Research Council , Canada Roberto Neagu/ Institute for Fuel Cell Innovation, National Research Council , Canada Rob Hui/ Institute for Fuel Cell Innovation, National Research Council , Canada Basil Marple/ Industrial Materials Institute, National Research Council , Canada |
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Suspension plasma spraying (SPS), in which a suspension of the desired material is fed into the plasma jet by an atomizing gas or high pressure, is an emerging technique. Because of using a liquid feedstock carrier, suspension plasma spray permits injection of finer powder, providing the possibility of producing sprayed coatings that are both thin and dense and have fine microstructures. These characteristics make suspension plasma spray an attractive process for depositing highly efficient electrodes and electrolytes for SOFC applications. In the present study, NiO-YSZ anode and YSZ electrolyte half cells were successfully deposited on porous Hastelloy X substrates by suspension plasma spray. The NiO-YSZ coating deposition process was optimized by design of experiment. The YSZ electrolyte coating spray process was examined by changing one parameter at a time. The results from the design-of-experiment trials indicate that the porosity of the as-deposited coatings increased with an increase of suspension feed rate while it decreased with an increase of total plasma gas flow rate, and standoff distance in the investigated ranges of process parameters. The deposition efficiency increased with an increase of total plasma gas flow rate, suspension feed rate and standoff distance. The possible reasons for the above stated observations are explained based on theoretical considerations. The microstructure examination by SEM shows that in the as-deposited anode layer the NiO and YSZ phases were homogenously distributed and that the YSZ phase had a lamellar structure. It was observed that the density of the YSZ electrolyte layer increased as input power of the plasma torch increased. As a result of the optimization process it was possible to produce porous anodes on half cells. Also the deposited electrolytes were dense and no interconnected pores appeared. No cracks were observed in either the deposited anode or electrolyte layer when optimized spray parameters were employed. |