Gaseous Conductivity Study on Silica Aerogel and Its Composite Insulation Materials

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Gaosheng Wei ◽  
Yusong Liu ◽  
Xiaoze Du ◽  
Xinxin Zhang
Keyword(s):  
Atmospheric Pressure ◽  
Silica Aerogel ◽  
Calcium Silicate ◽  
Experimental Results ◽  
Ceramic Fiber ◽  
Insulation Material ◽  
Insulation Materials ◽  
Transient Hot Strip ◽  
Hot Strip ◽  
Aerogel Composite

This paper presents a theoretical and experimental study on gaseous conductivity of silica aerogel and composite insulation materials. First, the insulation material samples (including silica aerogel, xonotlite-type calcium silicate, xonotlite-aerogel composite, and ceramic fiber-aerogel composite) were prepared. Next, the gaseous conductivities of the prepared samples were measured from 0.045 Pa to atmospheric pressure using the transient hot-strip (THS) method. The gaseous conductivity expressions obtained based on the kinetic theory were then compared with the experimental results. It is shown that the gaseous conductivity of both xonotlite-type calcium silicate and silica aerogel decreases significantly with decreasing pressure. The gaseous conductivities of xonotlite-type calcium silicate and silica aerogel reach zero at about 100 Pa and 104 Pa, respectively. The theoretical gaseous conductivity expressions match well with the experimental results of xonotlite-type calcium silicate and silica aerogel but not with the experimental results for the composite insulation materials. This mismatch indicates that the aerogel does not totally fill the original interspace of the xonotlite-type calcium silicate and ceramic fiber in the two kinds of composite insulation materials.

Gaseous Conductivity Study on Silica Aerogel and Its Composite Insulation Materials

2010 ◽  
Author(s):  
Gaosheng Wei ◽  
Yusong Liu ◽  
Xiaoze Du ◽  
Xinxin Zhang
Keyword(s):  
Experimental Study ◽  
Atmospheric Pressure ◽  
Silica Aerogel ◽  
Calcium Silicate ◽  
Experimental Results ◽  
Insulation Materials ◽  
Transient Hot Strip ◽  
Hot Strip ◽  
Aerogel Composite ◽  
Micro Level

This paper presented theoretical and experimental study on gaseous conductivity of silica aerogel and it’s composite insulation materials. The samples of silica aerogel, xonotlite-type calcium silicate, xonotlite-aerogel composite and ceramic fibre-aerogel composite insulation materials were prepared firstly. The gaseous conductivities of the prepared samples were measured from 0.045 Pa to atmospheric pressure with the transient hot-strip (THS) method. The gaseous conductivity expressions based on the kinetic theory were then compared with the experimental results. It is shown that both the gaseous conductivity of xonotlite-type calcium silicate and silica aerogel decreases significantly with the drop of pressure. The gaseous conductivity of xonotlite-type calcium silicate reaches to zero at about 100 Pa and the gaseous conductivity of silica aerogel reaches to zero at about 104 Pa. The theoretical gaseous conductivity expressions match well with the experimental results of xonotlite-type calcium silicate and silica aerogel respectively, but do not match with the experimental results for the composite insulation materials. It indicates that the aerogel does not fill the two kinds of composite insulation materials entirely, and some micro level pores still exist in them.

Thermal Radiation in Silica Aerogel and its Composite Insulation Materials

2011 ◽  
Author(s):  
Gaosheng Wei ◽  
Yusong Liu ◽  
Xinxin Zhang ◽  
Xiaoze Du
Keyword(s):  
Thermal Radiation ◽  
Extinction Coefficient ◽  
Silica Aerogel ◽  
Extinction Coefficients ◽  
Ceramic Fibre ◽  
Insulation Materials ◽  
Hot Strip ◽  
Aerogel Composite ◽  
Infrared Spectrometer ◽  
Spectral Extinction Coefficient

This paper engages in experimental measurements on thermal radiative transfer in silica aerogel and its composite insulation materials (xonotlite-aerogel composite and ceramic fibre-aerogel composite). The samples of silica aerogel, xonotlite-type calcium silicate, and ceramic fibre insulation materials are all considered as a semi-transparent medium capable of absorbing, emitting and scattering thermal radiation. The spectral transmittances are then measured at different infrared wavelengths ranging from 2.5 to 25μm with a Fourier transform infrared spectrometer (FTIR), and subsequently used to determine the specific spectral extinction coefficient and the specific Rossland mean extinction coefficient of the sample. The radiative conductivities deduced from the overall thermal conductivities measured with the transient hot-strip (THS) method are compared with the predictions from the diffusion approximation by using the measured spectral extinction coefficient. The results show that the spectral extinction coefficients of the samples are strongly dependent on the wavelength, particularly in the short wavelength regime (<10μm). The total Rossland mean extinction coefficients of the samples are all decreasing with the temperature increasing. The radiative conductivities are found almost proportional to the cubic temperature, and decreases as the sample density increases.

Preparation and Properties of Phase Change Thermal Insulation Materials

2018 ◽  
Vol 281 ◽  
pp. 131-136
Author(s):  
Shi Chao Zhang ◽  
Wei Wu ◽  
Yu Feng Chen ◽  
Liu Shi Tao ◽  
Kai Fang ◽  
...  
Keyword(s):  
Phase Change ◽  
Thermal Insulation ◽  
Calcium Silicate ◽  
Phase Change Materials ◽  
Performance Test ◽  
Thermal Protection ◽  
Insulation Material ◽  
Insulation Materials ◽  
Short Time ◽  
Change Material

With the increase of the speed of vehicle, the thermal protection system of its powerplant requires higher insulation materials. Phase change materials can absorb large amounts of heat in short time. So the introduction of phase change materials in thermal insulation materials can achieve efficient insulation in a limited space for a short time. In this paper, a new phase change thermal insulation material was prepared by pressure molding with microporous calcium silicate as matrix and Li2CO3 as phase change material. The morphology stability, exudation and heat insulation of the materials were tested. The results show that the porous structure of microporous calcium silicate has a good encapsulation when the phase transition of Li2CO3 is changed into liquid. And the material has no leakage during use. The thermal performance test also shows that the insulation performance of the material has obvious advantages in the short term application.

Mechanical and thermal properties of reticulated SiC aerogel composite prepared by template method

2019 ◽  
Vol 53 (28-30) ◽  
pp. 4117-4124
Author(s):  
Xinli Ye ◽  
Zhaofeng Chen ◽  
Sufen Ai ◽  
Junxiong Zhang ◽  
Bin Hou ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Silica Aerogel ◽  
Sol Gel ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Template Method ◽  
Mechanical And Thermal Properties ◽  
Insulation Material ◽  
Aerogel Composite

A novel structure-controllable reticulated silicon carbide (SiC) skeleton-reinforced silica aerogel composites (SiC/aerogel) were fabricated successfully by template method. Three-dimensional SiC skeletons prepared by different deposition time were prepared via the chemical vapor deposition technology, and then the silica aerogel was induced by the sol–gel process. The test results showed that the mechanical properties increased and thermal conductivities decreased remarkably after impregnating reticulated SiC skeleton with silica aerogel. The SiC/aerogel-24 possessed the highest compressive strength of 0.82 MPa with the thermal conductivity of 0.1597 W/(m·K) at 600℃, while the SiC/aerogel-12 exhibited the lowest thermal conductivity of 0.1244 W/(m·K) and its compressive strength was 0.64 MPa. The present work reported a novel method to manufacture the structure-controllable reticulated SiC aerogel composite which could be used as a high-temperature super-thermal insulation material for the potential applications.

scholarly journals Microstructure and Thermal Insulation Property of Silica Composite Aerogel

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 993 ◽  
Author(s):  
Lei Shang ◽  
Yang Lyu ◽  
Wenbo Han
Keyword(s):  
Thermal Insulation ◽  
Silica Aerogel ◽  
Infrared Radiation ◽  
Performance Test ◽  
Heat Insulation ◽  
Insulation Material ◽  
Cold Surface ◽  
Composite Aerogel ◽  
Aerogel Composite ◽  
Insulation Performance

Tetraethyl orthosilicate was selected as a matrix of heat insulating materials among three silanes, and an anti-infrared radiation fiber was chosen as a reinforcement for silica aerogel insulation composite. The silica aerogel was combined well and evenly distributed in the anti-infrared radiation fiber. The heat insulation effect was improved with the increase in thickness of the aerogel insulation material, as determined by the self-made aerospace insulation material insulation performance test equipment. The 15 mm and 30 mm thick thermal insulation material heated at 250 °C for 3 h, the temperatures at the cold surface were about 80 °C and 60 °C, respectively, and the temperatures at 150 mm above the cold surface were less than 60 °C and 50 °C, respectively. The silica aerogel composites with various thicknesses showed good thermal insulation stability. The silica insulation composite with a thickness of 15 mm exhibited good heat insulation performance, meets the thermal insulation requirements of general equipment compartments under low-temperature and long-term environmental conditions. The thermal conductivity of prepared silica aerogel composite was 0.0191 W·m−1·k−1 at room temperature and 0.0489 W·m−1·k−1 at 500 °C.

Studies on Thermal Property of Silica Aerogel/Epoxy Composite

2007 ◽  
Vol 546-549 ◽  
pp. 1581-1584 ◽  
Author(s):  
Jiu Peng Zhao ◽  
Deng Teng Ge ◽  
Sai Lei Zhang ◽  
Xi Long Wei
Keyword(s):  
Thermal Conductivity ◽  
Thermal Property ◽  
Epoxy Resin ◽  
Silica Aerogel ◽  
Epoxy Composite ◽  
Transfer Model ◽  
Insulation Material ◽  
Thermal Transfer ◽  
Heat Distortion Temperature ◽  
Ft Ir

Silica aerogel/epoxy composite, a kind of efficient thermal insulation material, was prepared by doping silica aerogel of different sizes into epoxy resin through thermocuring process. The results of thermal experiments showed that silica aerogel/epoxy composite had a lower thermal conductivity (0.105W/(m·k) at 60 wt% silica aerogel) and higher serviceability temperature (Martens heat distortion temperature: 160°C at 20 wt% silica aerogel). In addition, the composite doping larger size (0.2-2mm) of silica aerogel particle had lower thermal conductivity and higher Martens heat distortion temperature. Based on the results of SEM and FT-IR, the thermal transfer model was established. Thermal transfer mechanism and the reasons of higher Martens heat distortion temperature have been discussed respectively.

Polypropylene/Silica Aerogel Composite Incorporating a Conformal Coating of Methyltrimethoxysilane-Based Aerogel

2019 ◽  
Vol 19 (3) ◽  
pp. 1376-1381 ◽  
Author(s):  
Haryeong Choi ◽  
Vinayak G Parale ◽  
Kyu-Yeon Lee ◽  
Ha-Yoon Nah ◽  
Zied Driss ◽  
...  
Keyword(s):  
Silica Aerogel ◽  
Conformal Coating ◽  
Aerogel Composite
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