Synthesis and Characterization of Silica Aerogel Materials Doped with TiO₂ Powder for Thermal Insulation

Abstract:

Super insulation and hydrophobic silica-based aerogels doped with TiO₂ powder (8wt %) were successfully synthesized by using cost effective processing from Tetraeth oxysilane (TEOS). After aging and washing of wet gel, surface modification were modified using trimethylchlorosilane (TMCS) via one-step solvent exchange and surface modification. And the proper molar ratio of TMCS to pore water is 0.02. The microstructure and morphology of the ultralow density silica aerogels were characterized by the specific surface area, S_BET, SEM, and the pore size distribution techniques. From the results, the obtained aerogel doped with TiO₂ powder exhibited excellent physical properties with less than 10% volume shrinkage, extremely high specific surface area (652 m²/g) and super hydrophobicity (contact angle of~145°). It should be noted that TiO₂ powders are physically embedded by SiO₂ aerogel, and there is an obvious Ti–O–Ti and Si–O–Si bonding group based on structural analysis. The thermal properties of silica aerogel were determined using the Hot Disk device, composite aerogel exhibited thermal conductivities of 0.0426 W/m·K at 700°C, TiO₂ powders effectively suppressed the intensified thermal radiations at high temperatures to achieve ultralow thermal conductivities. These results have important implications for designing novel structure of porous materials of high performance for silica aerogels.

• Periodical: Key Engineering Materials (Volume 723)
• Pages: 492-496
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.723.492
• Online since: December 2016
• Authors: Guang Wu Liu*, Yan Gang Liu
• Keywords: Hydrophobic, Nano Materials, Silica Aerogel, Thermal Conductivity, TiO₂ Powder

References

[1] H. Husing, U. Schubert, Aerogels-Airy Materials: Chemistry, Structure, and Properties, Angew. Chem. Int. Ed. Engl. 37 (1998) 22-45.

[2] R . Hutter, T. Mallat, A. Baiker. Titania-Silica Mixed Oxides . 2. Catalytic Behavior in Olefin Epoxidation . J Catal 153 (1995) 77-189.

DOI: 10.1006/jcat.1995.1119

[3] G.W. Liu, B. Zhou, X.Y. Ni, J. Shen, G.M. Wu, A. Du, G.Q. Zu. Influence of thermal process on microstructural and physical properties of ambient pressure dried hydrophobic silica aerogel monoliths, J. Sol–Gel Sci. Tech. 62 (2012) 26-133.

DOI: 10.1007/s10971-012-2694-x

[4] A. V. Rao, R.R. Kalesh, Comparative studies of the physical and hydrophobic properties of TEOS based silica aerogels using different co-precursors, Sci. Technol. Adv. Mater. 4 (2003) 509–515.

DOI: 10.1016/j.stam.2003.12.010

[5] T. Y. Wei, S. Y. Lu, Y. C. Chang. A New Class of Opacified Monolithic Aerogels of Ultralow High-Temperature Thermal Conductivities. J. Phys. Chem. C, 113 (2009) 7424-7428.

DOI: 10.1021/jp900380q

[6] J. Kuhn, T. Gleissner, C. Arduini-schuster, S. Korder and J. Fricke, Integration of mineral powders into SiO2 aerogels. J. Non-Cryst. Solids. 186 (1995) 291.

DOI: 10.1016/0022-3093(95)00067-4

[7] D. J. Suh, T. J. Park, J. H. Sonn, J. C. Lim. Effect Of Aging On The Porous Texture Of Silica Aerogels Prepared By Nh4oh And Nh4f Catalyzed Sol-Gel Process. J. Mater. Sci. Lett. 18 (1999) 1473-1475.

[8] P. B. Sarawade, J. K. Kim, A. Hilonga, H. T. Kim, Korean. Influence of aging conditions on textural properties of water-glass-based silica aerogels prepared at ambient pressure. J. Chem. Eng. 27(4) (2010) 1301-1309.

DOI: 10.1007/s11814-010-0173-z

[9] G. W. Liu, B. Zhou, A. Du, J. Shen, Q. J. Yu, Effect of the thermal treatment on microstructure and physical properties of low-density and high transparency silica aerogels via acetonitrile supercritical drying. J. Porous. Mater. 20 (2013).

DOI: 10.1007/s10934-013-9699-x

[10] Y. G. Kwon, S. Y. Choi, E. S. Kang, et al. Ambient-dried silica aerogel doped with TiO2 powder for thermal insulation, J. Mater. Sci. 35 (2000) 6075-6079.