Sintering behaviour of alumina-modified silica aerogels

Saliger, R.; Heinrich, T.; Gleissner, T.; Fricke, J.

doi:10.1016/0022-3093(95)00080-1

Cited by 49 publications

(25 citation statements)

References 9 publications

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“…This feature eventually leads to the shrinkage of aerogel at high temperatures. For instance, SiO 2 aerogel showed a density increase by 65% after sintering at 1000 °C . Therefore, from the mechanical strength point of view, it is generally more desirable to attain low κ eff with small pore size rather than an exceedingly low density.…”

Section: High‐temperature Thermal Transport In Porous Materialsmentioning

confidence: 99%

Advanced Materials for High‐Temperature Thermal Transport

Shin

Wang

Luo

et al. 2019

Adv Funct Materials

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High temperature processes are widely used in a variety of existing and emerging industrial and aerospace applications. The thermal properties of high‐temperature materials thus play an important role in controlling the thermal energy, as highlighted by successful applications of thermal barrier coating and aerogels. While thermal transport processes at room and low temperature have witnessed tremendous progress in the past two decades, particularly on the fronts of understanding basic heat transfer properties at the micro‐ and nanoscale, the understanding at high temperature is still at the nascent stage, owing to several unique features at high temperature, such as the dominant Umklapp scattering effect that can render a crystalline material amorphous‐like thermal properties, and the important radiation contribution at high temperature. This lack of systematic understanding, coupled with the challenges in maintaining high‐temperature stability in a large number of materials, has limited the development of materials to meet the thermal transport properties pertaining to several current and emerging high‐temperature applications. This Review is aimed at providing an overview of the basic mechanisms governing thermal transport processes at high temperature, to identify their unique features and challenges, and to explore opportunities in material research for high‐temperature thermal materials.

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Section: High‐temperature Thermal Transport In Porous Materialsmentioning

confidence: 99%

Advanced Materials for High‐Temperature Thermal Transport

Shin

Wang

Luo

et al. 2019

Adv Funct Materials

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Section: Introductionmentioning

confidence: 99%

“…Alumina and aluminosilicate aerogels are of interest as constituents of thermal insulation systems with potential for use at temperatures higher than those attainable with silica aerogels, which densify and sinter at temperatures above 600-700°C. [1][2][3] Addition of alumina, in combination with silica, has been shown to delay sintering to higher temperatures, 3,4 with increases in sintering temperature achieved using as little as 0.01 mole% Al 2 O 3 (from boehmite) added to silica on a nanoscale. 4 Several solgel methods have been reported in the preparation of alumina and aluminosilicates, including use of aluminum alkoxides, [5][6][7][8][9][10][11] aluminum salts, including AlCl 3 12,13 and from colloidal dispersions of aluminum hydroxides, 7 including the use of colloidally dispersed boehmite.…”

Section: Introductionmentioning

confidence: 99%

“…7,[19][20][21] In aluminosilicate aerogels, the extent of aluminum incorporation also is shown to vary with the precursor route. 20 The current work focuses on synthesizing alumina and aluminosilicate aerogels using two precursor routes: (i) AlCl 3 and propylene oxide (PO) or (ii) a colloidal route using several boehmite starting powders. In both routes, tetraethoxysilane (TEOS) is used as the silicon source.…”

Section: Introductionmentioning

confidence: 99%

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Optimization of Alumina and Aluminosilicate Aerogel Structure for High‐Temperature Performance

Hurwitz

Gallagher

Olin

et al. 2014

Int J of Appl Glass Sci

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Alumina and aluminosilicate aerogels offer potential for use at temperatures above 700°C, where silica aerogels begin to sinter. Stability of alumina and aluminosilicate pore structures at high temperatures is governed by the starting aerogel structure, which, in turn is controlled by the synthesis route. Structure, morphology, and crystallization behavior are compared for aerogels synthesized from AlCl 3 and propylene oxide with those synthesized from a variety of boehmite precursors. The aerogels possessing a crystalline boehmite structure in the as-synthesized condition retained mesoporous structures to temperatures of 1200°C, while the AlCl 3 -derived aerogels, although exhibiting higher as-synthesized surface areas, crystallized and densified at 980-1005°C.

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“…Thus, the sintering behavior of SiO 2 is related to its viscosity at a given temperature. In the case of sintering of an SiO 2 Al 2 O 3 composite (Si:Al = 1:3.68, molar ratio), 17) the viscosity of the SiO 2 at 1000°C was found to increase by the addition of Al 2 O 3 , since the viscous flow of Al 2 O 3 particles does not proceed at this temperature. In the present study, therefore, it is presumed that the rigid Al 2 O 3 nanoparticles inhibited sintering of the SiO 2 nanoparticles by increasing the viscosity of the nanocomposite at the heat treatment temperature.…”

Section: Discussionmentioning

confidence: 96%

Fabrication and photoluminescence of monolithic silica glass doped with alumina nanoparticles using SiO<sub>2</sub>-PVA nanocomposite

Ikeda

Murata

Fujino

2015

J. Ceram. Soc. Japan

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Al 2 O 3 nanoparticle doped SiO 2 -PVA nanocomposites were prepared using fumed silica, fumed alumina, and poly(vinyl alcohol) (PVA). Nanocomposites containing from 0 to 6 mol % Al 2 O 3 were heat-treated in air at 1100 to 1300°C to obtain monolithic, transparent silica glass. The 0.6 mol % Al 2 O 3 doped nanocomposite was sintered at 1200°C, a higher temperature than was required for the non-doped nanocomposite. The obtained Al 2 O 3 doped silica glass exhibited characteristic blue photoluminescence (PL) on UV excitation. The effects of the Al 2 O 3 nanoparticles on the sintering temperature and the PL characteristics of the sintered silica glass are discussed in terms of the morphology and structure of the sintered glass.

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Sintering behaviour of alumina-modified silica aerogels

Cited by 49 publications

References 9 publications

Advanced Materials for High‐Temperature Thermal Transport

Advanced Materials for High‐Temperature Thermal Transport

Optimization of Alumina and Aluminosilicate Aerogel Structure for High‐Temperature Performance

Fabrication and photoluminescence of monolithic silica glass doped with alumina nanoparticles using SiO<sub>2</sub>-PVA nanocomposite

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