Preparation and Microstructures of Nano-Porous SiO2 Thermal Insulation Materials by Freeze-Casting of SiO2 in TBA/H2O Suspensions
A kind of porous SiO2 bulk materials with pore size distributed in nano and micron scales has been fabricated by freeze-casting of SiO2 nano-size powders in TBA (tert-butyl alcohol)/H2O suspensions. The content of TBA in the well mixed TBA/H2O binary co-solvent plays an important role in size and morphology control of the pores in the obtained SiO2 monolithic materials, since the ratio of TBA/H2O determines the competition of crystallization of TBA and ice, therefore, the microstructure of the monolithic SiO2. It was found that the content of TBA in the range from 30 to 40% was suitable for formation of more nano-pores in the SiO2 monolith. The insulation materials freeze-casted from the suspension of SiO2 in 13wt% and TBA in 40wt% has the density of 0.17g/cm3, and the specific surface area of 282m2/g. The pore size has a trimodal size distribution with three mean diameters of 15nm, 100nm and 4μm, respectively.
Wei Pan and Jianghong Gong
J. Tang et al., "Preparation and Microstructures of Nano-Porous SiO2 Thermal Insulation Materials by Freeze-Casting of SiO2 in TBA/H2O Suspensions", Key Engineering Materials, Vols. 512-515, pp. 315-318, 2012