Modeling and coupling effect evaluation of thermal conductivity of ternary opacifier/fiber/aerogel composites for super-thermal insulation

Nano-porous silica aerogel material exhibits extensive application prospects in aerospace, industry and buildings for excellent thermal insulation and energy efficiency owing to its ultra-low thermal conductivity. To further improve the high-temperature thermal insulation and mechanical property of aerogels, infrared opacifiers and reinforcing fibers are added into the aerogel matrix to form ternary opacifier/fiber/aerogel composites. In this study a theoretical model of predicting thermal conductivity of the ternary opacifier/fiber/aerogel composite is presented and validated with experimental results. Based on the model the effects of ternary opacifier/fiber/aerogel contents on the thermal conductivity are investigated by using a seven-batch ternary factorial design. A super-thermal insulation of 0.0185 W (.) m(-1) (.) K-1 is achieved when the ternary opacifier/fiber/aerogel contents are 10 wt%, 5 wt% and 85 wt% respectively. The coupling effect of the ternary opacifier/fiber/aerogel contents on the thermal conductivity of the composites is then explored to decrease the coupling thermal conductivity and improve the thermal insulating performance of the ternary aerogel composites. The results indicate that the coupling thermal conductivity can be decreased by enlarging the difference between the fiber and opacifier contents. This study could be used in the design of ternary opacifier/fiber/aerogel composites for improving their super-thermal insulation. (C) 2017 Elsevier Ltd. All rights reserved.