T. W. Coyle, Centre for Advanced Coating Technology, University of Toronto, Toronto, ON, Canada; Y. Wang, Ohio State University, Columbus, OH
Although Ni-YSZ anode coating deposition by conventional plasma spray is more successful than other SOFC components, the large Ni and YSZ particles used for the spray process, which are about 50-150 microns for high porosity coating deposition, reduce the density of three phase sites for electrode reaction. In this paper, the solution precursor plasma spraying (SPPS) process, in which solution precursors of the desired resultant materials are fed into a DC plasma jet by atomizing gas, was used to simultaneously synthesize Ni-YSZ composite and deposit porous anode coatings. A design of experiments (DOE) technique was used to optimize the process parameters. The deposition results show that the process parameters have significant effects on both the deposition rate and the microstructure of the deposited coating. The coating was composed of larger splats at high deposition rate while it consists of smaller splats at low deposition rate. After heat treatment to reduce the NiO present in the as deposited coatings, the splats were found to contain small spherical YSZ particles about 0.5 micrometers in diameter. Previously molten Ni forms a network through the gaps between the YSZ particles. The coatings have 20% to 50% porosity depending on the process parameters.
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