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2764 |
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Wednesday, September 28, 2011, Saal C2.1 4:50 PM Medical Industry 1 |
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The importance of powder morphology for cold spraying of titanium dioxide |
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Noviana Tjitra Salim* / Toyohashi University of Technology, Japan Motohiro Yamada / Toyohashi University of Technology, Japan Hiromi Nakano/ Toyohashi University of Technology, Japan Koichiro Shima/ Toyohashi University of Technology, Japan Hiroaki Isago/ Toyohashi University of Technology, Japan Masahiro Fukumoto/ Toyohashi University of Technology, Japan |
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Titanium dioxide (TiO2) is unique material that has wide potential especially in the area of photocatalysis. It can be coated on large surfaces such as building or housing walls for air purification. Thermal spray process is well known to be suitable for large area coating deposition. However, the photocatalytic property of thermal sprayed TiO2 coating is relatively low due to the anatase-rutile phase transformation that occurs well below the melting temperature of TiO2. Due to this reason, cold spray process is considered to be more suitable for the deposition of TiO2 coating for photocatalysis as it is a solid phase deposition method that will not cause high temperature phase transformation. However, cold spraying of ceramic materials, including TiO2 is difficult due to its hardness and brittleness. We have developed several TiO2 powders with unique structures and they can be cold sprayed. The synthesis method involved the hydrolysis of titanyl sulphate in water. By modifying the hydrolysis method, the TiO2 structure can be easily altered. We have discovered that the cold sprayability of TiO2 is dependent on its structure. The mechanical properties of the cold spray coating are also dependent highly on the TiO2 feedstock powders. This study shows the important structures that a TiO2 powder has to have in order to have high mechanical properties when cold sprayed. We believe that agglomerated structure with the primary particles oriented in one single crystal axes to be important for the mechanical properties of cold sprayed TiO2 coating. |