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4679 |
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Wednesday, May 11, 2016, Room 3E 4:40 PM Suspension Spraying III |
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Fracture characteristics of high-velocity suspension flame sprayed aluminum oxide coatings |
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Jarkko Kiilakoski* / Tampere University of Technology, Finland Axel Lutoschkin / Institute for Manufacturing Technologies of Ceramic Components and Composites, University Of Stuttgart, Germany Philipp Müller/ Institute for Manufacturing Technologies of Ceramic Components and Composites, University Of Stuttgart, Germany Marian Apostol/ Department of Materials Science, Tampere University of Technology, Finland Heli Koivuluoto/ Department of Materials Science, Tampere University of Technology, Finland Andreas Killinger/ Institute for Manufacturing Technologies of Ceramic Components and Composites, University Of Stuttgart, Germany Petri Vuoristo/ Department of Materials Science, Tampere University of Technology, Finland |
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A recent trend of development in thermally sprayed ceramic coatings is to decrease their most defining attribute, brittleness. One possible strategy to improve ductility is to alter the coating towards a finer microstructure: Due to the smaller size of the splats, the amount of crack-arresting interfaces increases. High-velocity suspension flame-spraying (HVSFS) is an emerging thermal spraying technique, which utilizes a liquid as the powder carrier instead of gas, as in the more traditional spraying techniques. This allows for nano- or submicrometer-sized granular structures to be achievable with HVSFS. The aim of this work is to evaluate the brittleness of suspension sprayed aluminum oxide (Al2O3) coatings with various methods, including Vickers Indentation Fracture Toughness, 4-point bending and High-Velocity Particle Impactor. Coatings were sprayed with HVSFS using suspensions of isopropanol and water solvents. Additionally, high-velocity oxy-fuel (HVOF) sprayed commercially available Al2O3-powder feedstock was used as a reference. Differences in the melting degrees of the HVSFS-coatings were found, leading to different cracking behaviors in all tests. Both HVSFS-coatings showed improvements compared to traditional HVOF-coating. |