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3892 |
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Friday, May 23, 2014, Hall A 2:40 PM Suspension Spraying 2 |
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Optical alumina coatings deposited by suspension spraying |
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Motohiro Yamada / Toyohashi University of Technology, Japan Kazuaki Furukawa / Toyohashi University of Technology, Japan Takaaki Sunada/ Toyohashi University of Technology, Japan Masahiro Fukumoto/ Toyohashi University of Technology, Japan Shinobu Ito/ OPTCOM Co., Ltd, Japan A. Ganesan*/ , |
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The coating which possesses high reflection properties from near-UV to IR wavelength region is required inside wall of integrated spheres. The integrated spheres are required to evaluate the optical properties of LED. Conventional methods to produce the inside wall of the integrated spheres requires organic binder to keep reflection ceramic powders on the surface. However, recent LED technology uses UV regions and it damages organic materials in the reflection coating. Therefore, pure ceramic coatings with high reflection property without including organic materials are required for the integrated sphere application. In this study, high quality alumina coatings were fabricated by suspension spray process and evaluated its reflection property. Furthermore, the relation between the coating structure and optical properties were also investigated. It was possible to fabricate alumina coatings by conventional plasma spray process, but it was difficult to fabricate high reflection in UV region due to phase transformation. On the other hand, suspension plasma sprayed coatings with maintaining original alpha-alumina possessed high reflection property from near-UV to IR region. The coating thickness significantly affected the reflection property for all wavelength regions. However, surface roughness and macro-porosity didnt affect the reflection properties. Therefore, thick alumina coatings with maintaining original alpha phase can be applied for the integrated spheres. |