Applications of Aerogels in Space Exploration

Jones, Steven M.; Sakamoto, Jeffrey

doi:10.1007/978-1-4419-7589-8_32

Cited by 17 publications

(15 citation statements)

References 34 publications

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“…There are currently many applications of aerogels, such as catalysts [ 2 ], insulators [ 3 ], sensors [ 9 ] environmental [ 10 ] and biomedical applications [ 11 , 12 ], etc., and the potential uses of these materials are even larger if one considers the aerogel as a precursor. Through heat treatments, the silica aerogels can indeed be sintered into silicate glasses and glass ceramics [ 13 , 14 ].…”

Section: Introductionmentioning

confidence: 99%

Fractal Structure in Silica and Composites Aerogels

Woignier

Primera

Alaoui

et al. 2020

Gels

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Silica aerogels are known to be materials with exceptional characteristics, such as ultra-low density, high surface area, high porosity, high adsorption, and low-thermal conductivity. In addition, these unique properties are mainly related to their specific processing. Depending on the aerogel synthesis procedure, the aerogels texture can be tailored with meso and/or macroporosity. Fractal geometry has been observed and used to describe silica aerogels at nanoscales in certain conditions. In this review paper, we describe the fractal structure of silica aerogels that can develop depending on the synthesis conditions. X-ray and neutron scattering measurements allow to show that silica aerogels can exhibit a fractal structure over one or even more than two orders of magnitude in length. The fractal dimension does not depend directly on the material density but can vary with the synthesis conditions. It ranges typically between 1.6 and 2.4. The effect of the introduction of silica particles or of further thermal treatment or compression of the silica aerogels on their microstructure and their fractal characteristics is also resumed.

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Section: Introductionmentioning

confidence: 99%

Fractal Structure in Silica and Composites Aerogels

Woignier

Primera

Alaoui

et al. 2020

Gels

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“…Aerogels can be utilized in numerous applications and they have first been used as catalysts or insulating materials (sound and temperature) [2,8,9,10]. More recently aerogels are employed in the field of the environment [11][12][13], green haouse gazes captors [14,15], pharmaceuticals [16,17] but also in exotic applications such as cosmic dust and space debris sensors [21][22][23] or nuclear wastes containment materials [18][19][20]. Like any type of material for a defined application, knowledge of their mechanical properties is necessary.…”

Section: Introductionmentioning

confidence: 99%

Techniques for characterizing the mechanical properties of aerogels

Woignier

Primera

Alaoui³

et al. 2019

J Sol-Gel Sci Technol

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In this paper, we present the different characterization techniques used to measure the mechanical properties of silica aerogels. The mechanical behaviour of aerogels is generally described in terms of elastic and fragile materials (such as glasses or ceramics) but also in terms of plastic media in compression testing. Because of these very different mechanical behaviors, several types of characterization techniques are proposed in the literature. We first describe the dynamic characterization techniques such as ultrasounds, Brillouin scattering, dynamic mechanical analysis (DMA) to measure the elastic properties: Young's modulus (E) , shear modulus (G), poisson ratio (υ) but also attenuation and internal friction. Thanks to "static" techniques such as three-point bending, uniaxial compression, compression we also access to the elastic modulus (E) and to the rupture strength (σ). The experimental results show that the value of the elastic and fracture moduli measured is several orders of magnitude lower than that of a material without porosity. With regard to the brittleness characteristics, Weibull's analysis is used to show the statistical nature of the fracture resistance. We also present the SENB (single edge notched beam technique) technique to characterize toughness (K1C) and the stress corrosion mechanisms, which are studied in ambient conditions and temperature by the double-cleavage drilled compression experiment (DCDC). In the last part of the paper, we show how, during the isostatic compression test, aerogels behave like plastic materials.The data allow calculating the bulk modulus (K), the amplitude of the plastic deformation and the yield strength (σel), which is the boundary between the elastic and plastic domains. These different techniques allow understanding which parameters influence the overall mechanical behavior of aerogels, such as pore volume, but also pore size, internal connectivity and silanol bounds content. It is shown that pore size plays a very important role; pores can be considered as flaws in the terms of fracture mechanics.

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“…TEG technology typically consists of semiconducting elements, which convert a heat flux into a DC voltage that can be used to drive an external load, and a heat management system whereby thermal insulation is needed to reduce parasitic heat loss [3,4]. At present, aerogel-based insulation is under development for space TEG technology [5]. Aerogel was first produced in the 1930s [6], and is a unique class of materials exhibiting high specific surface area (200-1200 m 2 /g), high porosity (80-99%), low density (< 0.05 g/cm 3 ) and low thermal conductivity (< 0.02 W/(m.K)) [7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Cast-in-place, ambiently-dried, silica-based, high-temperature insulation

et al. 2017

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A novel sol-gel chemistry approach was developed to enable the simple integration of a cast-inplace, ambiently-dried insulation into high temperature applications. The insulation was silicabased and synthesized using methyltrimethoxysilane (MTMS) as the precursor. MTMS created a unique silica microstructure that was mechanically robust, macroporous, and superhydrophobic.To allow for casting into and around small, orthogonal features, zirconia fibers were added to increase stiffness and minimize contraction that could otherwise cause cracking during drying.Nano-sized titania powder was incorporated as an opacifier to reduce radiative heat transport. To assess relevance to high temperature thermoelectric generator technology, a comprehensive set of materials characterization experiments were conducted. The silica gel was thermally stable, retained superhydrophobicity with a water contact angle >150°, and showed a high electrical resistance >1 G ohm, regardless of heating temperature (up to 600 °C in Ar for 4 h). In addition,The silica-based thermal insulation exhibited a Young's modulus ~3.7 MPa and a low thermal conductivity < 0.08 W/(m.K) at room temperature before and after heat treatment (up to 600 °C in Ar for 4 h). Thus, based on the simplicity of the manufacturing process and the optimized material properties, we believe this technology can act as an effective cast-in-place thermal

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Applications of Aerogels in Space Exploration

Cited by 17 publications

References 34 publications

Fractal Structure in Silica and Composites Aerogels

Fractal Structure in Silica and Composites Aerogels

Techniques for characterizing the mechanical properties of aerogels

Cast-in-place, ambiently-dried, silica-based, high-temperature insulation

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