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2208 |
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Wednesday, May 05, 2010, Hullet Room 10:40 AM Corrosion Protection |
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Thermally sprayed oxide ceramic coatings for demanding wear and corrosion applications
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Kari Niemi* / Tampere University of Technology
Department of Materials Science, Finland Jussi Laurila / Tampere University Of Technology, Department of Materials Science, Finland Petri Vuoristo/ Tampere University Of Technology, Department of Material Science, Finland Jari Knuuttila/ Millidyne Oy, Finland Filofteia-Laura Toma/ Fraunhofer Institute for Material and Beam Technology, Germany Lutz-Michael Berger/ Fraunhofer Institute for Material and Beam Technology, Germany |
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Oxide ceramic coatings deposited by atmospheric plasma spraying (APS) are widely used in wear applications. Wear resistance can, however, be significantly improved as modern high velocity spray methods are used. In this study high velocity oxygen fuel (HVOF) methods were used to deposit various coatings, such as alumina, alumina-titania, alumina-chromia and titania. Reference coatings were corresponding coatings deposited by APS. Alumina-chromia coatings were included with the aim to stabilize the α-Al2O3 phase content of the sprayed coating as α-Al2O3 phase possess better wear and corrosion characteristics than the γ-Al2O3 phase normally present in thermally sprayed coatings. Coatings were evaluated by optical microscopy, microhardness measurements, XRD and SEM. Wear resistance of the coatings was tested with the rubber-wheel abrasion test. Corrosion characteristics of the coatings were evaluated by the exposure tests at a wide pH range. Alumina based coatings deposited by HVOF resulted in high quality coatings with a dense microstructure, high wear resistance and improved resistance against corrosion. The results will be presented and discussed. |