Synthesis of fibre reinforced Al2O3−SiO2 aerogel composite with high density uniformity via a facile high-pressure impregnation approach

Abstract

Alumina-silica (Al2O3?SiO2) aerogel composite, with low density, low thermal conductivity and hightemperature stability, is attracting increased interest in the field of thermal insulation application. In this paper, a novel way to fabricate fibre reinforced Al2O3?SiO2 aerogel composite via a facile high-pressure impregnation approach was reported. Two Al2O3?SiO2 aerogel composites, HPe and LPe, were synthesized via high-pressure and low-pressure impregnation approach, respectively. The effects of the impregnation approach on the aerogel composites performance were studied, and the impregnation model was established. The results showed that the as-prepared HPe exhibited higher density uniformity, better high-temperature stability, higher specific surface area and lower thermal conductivity. It was also shown that the effect of impregnation approach on the mean density and morphology of the aerogel composites is negligible. However, the standard deviation of density (0.00857) and mean thickness shrinkage (9.98%) of HPe were 37.8% and 15.4% lower than that of LPe, respectively. The specific surface area (884.1m2/g) of HPe was 43.5% higher than that of LPe. The thermal conductivity of HPe at 1100?C was 2.74% lower than that of LPe. The impregnation model of the aerogel composites presented that the density uniformity and thermal conductivity of HPe were improved obviously, because there were less large pores in HPe than in the LPe.