• Journal of the Korean Ceramic Society
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• v.36 no.8
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• pp.829-834
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• 1999

The silica aerogels opacified via adding oxides were prepared by the sol-gel supercritical drying technique and their characteristics of mechanical strength and thermal conduction were investigated. The compressive strength of SiO2-10 mol% TiO2 and SiO2-10mol% Fe2O3 aerogels were 0.11 and 0.047 MP a respectively much higher than 0.025 MPa of pure silica aerogels. The thermal conductivity of silica aerogels opacified by TiO2 was as low as 0.02505 W/m${\cdot}$K at $400^{\circ}C$ It was found that the TiO2 -opacifier for improving mechanical strength and suppressing high temperature conduction of pure silica aerogels was more effective than the Fe2O3 -opacifier

• Journal of the Korean Ceramic Society
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• v.53 no.4
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• pp.386-392
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• 2016

Heat insulation plates of fumed silica were prepared by mixing fumed silica, SiC powder and chopped glass fiber by a high speed mixer followed by pressing of the mixture powder in a stainless steel mold of $100{\times}100mm$. Composition of the plates, particle size of SiC, and type of inorganic binder were varied for observation of their contribution to heat insulation of the plate. The plate was installed on the upper portion of an electric furnace the inside temperature of which was maintained at $400^{\circ}C$ and $600^{\circ}C$, for investigation of heat transfer through the plate from inside of the electric furnace to outside atmosphere. Surface temperatures were measured in real time using a thermographic camera. The particle size of SiC was varied in the range of $1.3{\sim}17.5{\mu}m$ and the insulation was found to be most excellent when SiC of $2.2{\mu}m$ was incorporated. When the size of SiC was smaller or larger than $2.2{\mu}m$, the heat insulation effect was decreased. Inorganic binders of alkali silicate and phosphate were tested and the phosphate was found to maintain the heat insulation property while increasing mechanical properties.

• Journal of the Korean Ceramic Society
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• v.44 no.12
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• pp.747-750
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• 2007

The thermal conductivities of nano-sized fumed silica-based insulation media were investigated by varying a mean particle size of the silicon carbide opacifiers and ceramic fiber content. Opacifying effect of ceramic fiber and silicon carbide powders was discussed in terms of their content and the mean particle size of them. As the fiber contents increased from 10 wt% to 30 wt% in a material, its thermal conductivity at temperatures of about $620^{\circ}C$ decreased from 0.171 $Wm^{-1}K^{-1}$ to 0.121 $Wm^{-1}K^{-1}$. Meanwhile, the thermal conductivity at temperatures of about $625^{\circ}C$ decreased from 0.128 $Wm^{-1}K^{-1}$ to 0.092 $Wm^{-l}K^{-1}$ as the mean SiC particle size decreased from $31{\mu}m$ to $10{\mu}m$.