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2779 |
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Thursday, September 29, 2011, Saal A 10:15 AM Industrial Gas Turbines 2 |
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Characterization of ceramic coatings made by thin film low pressure plasma spraying (LPPS-TF) |
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Andreas Hospach* / Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung (IEK-1), Germany Georg Mauer / Forschungszentrum Jülich GmbH, IEK-1, Germany Robert Vaßen/ Forschungszentrum Jülich GmbH, IEK-1, Germany Detlev Stöver/ Forschungszentrum Jülich GmbH, IEK-1, Germany |
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The thin film low pressure plasma spray process (LPPS-TF) has been developed with the aim of depositing uniform and thin coatings with large area coverage by plasma spraying. At high power input (~150 kW) and very low pressure (~100 Pa) the plasma jet properties change considerably and it is even possible to evaporate the powder feedstock material providing advanced microstructures of the deposits. This relatively new technique bridges the gap between conventional plasma spraying and physical vapor deposition. In addition, the resulting microstructures are unique and can hardly be obtained by other processes. In this paper, the particular plasma characteristics at very low pressure are discussed. The use of optical emission spectroscopy helped to identify the influence of plasma parameters. Microstructures made by LPPS-TF are shown and the columnar layer growth by vapor deposition is demonstrated. Applications of such structures in thermal barrier coatings (made of YSZ) and their cycling behavior are presented. Further ceramic materials like TiO2, Al2O3 or MgAl2O4 were also processed and the appropriate results are shown. |