STUDY ON THE THERMAL INSULATION PROPERTY OF SiO2 AEROGEL INFLUENCED BY THE PHENOLIC RESIN PYROLYSIS GAS PERMEATION

Phenolic resin is commonly used as the adhesive to strengthen the SiO2 aerogel thermal insulator on the aerospace vehicle. However, the pyrolysis of phenolic resin adhesives would alter the thermal insulation property of the SiO2 aerogel. In this research, experimental and numerical methods are adopted to investigate the influence of the pyrolysis gas on the heat transfer in the SiO2 aerogel. The results demonstrate that the gas convection is suppressed by the nanoporous structure of the SiO2 aerogel, but the pyrolysis gas of the adhesive would still significantly reduce the thermal insulation property of the SiO2 aerogel, and the thermal insulation property of the SiO2 aerogel would be seriously deteriorated, with the increasing amount of the phenolic resin used. As the operating pressure increases, the influence of the pyrolysis gas permeation on the heat transfer in the SiO2 aerogel is moderated due to the increasing of the density of gas stored in the SiO2 aerogel. The thermal insulation property of the SiO2 aerogel-based thermal insulation system becomes better at higher operating pressure conditions.