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Porous TiO2-Y2O3 Ceramics with Specific Infrared-Optical Properties
G. Steinborn1, G. Tzschichholz1, J. Guenster1, M.H. Keller2, J. Manara2
1 BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12200 Berlin (Germany);
2 Bavarian Center for Applied Energy Research (ZAE Bayern), Am Hubland, 97074 Wuerzburg (Germany)
received March 20, 2011, recieved in revised form April 28, 2011, accepted May 31, 2011
Vol. 2, No. 3, Pages 183-190 DOI: 10.4416/JCST2011-00011
Abstract
The infrared-optical properties and particularly the emissivity of sintered ceramics depend on the material's bulk properties and structural properties such as porosity, pore size distribution and pore diameter. The infrared-optical properties can be varied across a wide range by specifically selecting the material's bulk and structural properties. A major concern of the present study is the development of a ceramic coating material with a total emissivity below 0.2 at a temperature of 800 °C. For this purpose, various samples of a TiO2-Y2O3 (TY) ceramic composite were produced with different properties. On variation in the Y2O3 content from 5 to 60 wt%, the porosity of the ceramic composites varies from 3 % to 47 % with the mean pore diameter lying in a range from 0.3 μm to 1.7 μm. The addition of graphitic pore builders increases the porosity up to 60 % and the mean pore diameter to a maximum of 15 μm. By optimizing the total porosity and the pore size of the TY ceramics, a total emissivity as low as 0.17 at 800 °C could be achieved.
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Keywords
Oxide ceramic, porosity, mean pore diameter, infrared optical properties, emissivity
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