A three-dimensional network modifier (dimethyldiethoxysilane) makes ZrO2-SiO2 aerogel with excellent thermal insulation performance and high-temperature stability

Abstract

Dimethyl-diethoxysilane-modified ZrO2-SiO2 aerogels (DDS/ZSAs) have been prepared by using diethoxydimethylsilane as a co-precursor in the sol-gel process. Dimethyldiethoxysilane acts as a modifier for the three-dimensional structure and composition of aerogels. The pore volume increased from 1.65 cm3/g to 3.21 cm3/g, and the thermal conductivity decreased from 0.03013 Wm−1K−1 to 0.02332 Wm−1K−1 at room temperature. The number of hydroxyl groups on the aerogel surface is effectively reduced, and the particle growth caused by hydroxyl condensation was inhibited during firing. The increase in the number of Si-O-Zr bonds inhibited the growth of t-ZrO2, the phase transition temperature of the aerogel was significantly improved, and the crystallinity and crystal plane types were significantly reduced. Therefore, the porous microstructure of the modified aerogel remains good at 1000 °C. After heat treatment at 1000 °C, it still has a high specific surface area (259.6 m2/g), a high pore volume (1.51 cm3/g), and a low thermal conductivity (0.04206 Wm−1K−1). The thermal insulation performance and temperature resistance of ZrO2-SiO2 aerogels were double improved. In addition, DDS/ZSAs have high hydrophobicity and can be used in harsh wet and high-temperature environments. The research work is instructive for the design of superthermal insulation materials with high thermal stability and low thermal conductivity.