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5514 |
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The influence of powder particle size and solvent type on the microstructure of SPS coatings |
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Pawel Sokolowski / Wroclaw University of Science and Technology, Poland Monika Michalak/ Wroclaw University of Technology, Poland Rolando T. Candidato Jr./ University of Limoges, France Andrzej Ambroziak/ Wroclaw University of Technology, Poland Leszek Latka/ Wroclaw University of Technology, Poland |
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The development of Suspension Plasma Spraying (SPS) was caused by the difficulties with using conventional Powder Plasma Spraying (PPS) for a production of finely-grained coatings. The use of suspensions allowed introducing submicrometer- or even nanometer-sized powders into the plasma jet. However, the suspension formulation is one of the most important steps in SPS. This work was done in order to verify if the powder particle size or solvent type can be a key factors influencing microstructure of Suspension Plasma Sprayed coatings. Five various sets of coatings were produced by Suspension Plasma Spraying (SPS) methods. The variable spray parameters were powder particle size and solvent type. The coatings were deposited by using submicrometer-sized (dv50L1µm and dv50L0.5µm) and nanometer-sized (dv50L100nm) liquid feedstock. In each case the powder material was a well-known 8 wt.% yttria-stabilized zirconia. The pure ethanol or a mixture of water and ethanol were used as a solvents. The spray process was designed using 2k full factorial design. The use of liquid feedstocks having different powder particles size and solvent type influenced the grain size and microstructural features of zirconia coatings. The microstructural characterization was performed by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Electron Backscatter Diffraction (EBSD) as well. The attention was paid on the coating morphology, grain size and shape of grains. Finally, the correlation between powder particle size, solvent type and spray process efficiency was evaluated also. |