Improvement of thermal insulation and compressive performance of Al2O3–SiO2 aerogel by doping carbon nanotubes

Abstract

Carbon nanotubes (CNTs) have attracted significant attention from researchers due to their high specific strength and good extinction properties. In this study, Al2O3–SiO2 aerogel composites doped with 0–1.0 wt% CNTs were prepared by sol-gel and supercritical drying technologies, and the effects of CNT content on their microstructure, mechanical properties, heat insulation properties, and theoretical thermal conductivity were examined. With an increase in the CNT amount, the specific surface area and pore diameter of the aerogel composites decreased, while their compressive properties were enhanced. The obtained results revealed that the 1.0 wt% CNT-doped Al2O3–SiO2 aerogel composite exhibited the best comprehensive properties, while its thermal conductivity of 0.178 W/mK at 1000 °C was 15% lower than that of pure aerogel. In addition, the theoretical thermal conductivities of all samples were calculated in the temperature range of 25–1000 °C. This study explained that the addition of CNTs can significantly improve the comprehensive properties of Al2O3–SiO2 aerogel composites.