scholarly journals Advanced Opacified Fiber-Reinforced Silica-Based Aerogel Composites for Superinsulation of Exhaust Tubing Systems in Semi-Stationary Motors

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2677
Author(s):  
Markus Heyer ◽  
André Berkefeld ◽  
Pascal Voepel ◽  
Barbara Milow
Keyword(s):  
Silica Aerogel ◽  
Sol Gel ◽  
Three Dimensional ◽  
Casting Process ◽  
Supercritical Drying ◽  
Catalyst System ◽  
Fiber Reinforced ◽  
Molding Process ◽  
Material Evaluation ◽  
Pipe Insulation

Within this study, monolithic three-dimensional silica aerogel (SA) composite parts with super insulating properties are presented. A generic part based on fiber-reinforced (FR) silica aerogel for thermal insulation of the exhaust tubing system—to keep the exhaust gases as hot as possible to improve the efficiency of the catalyst system—was produced via a sol-gel-based molding process in combination with a supercritical drying using scCO2. A thermal conductivity of 16 mW m−1 K−1 was measured via a heat flow meter technique. In this manuscript, we present a full cycle of the material compound design, starting with fundamental material evaluation including aerogel optimization, opacifier influence, and casting process. The obtained generic part in shape of a half-shell for pipe insulation is characterized under real conditions.

New Transparent Substrate with Silica Aerogel Film for Surface-Emissive Devices

2000 ◽  
Vol 660 ◽  
Author(s):  
H. Yokogawa ◽  
K. Kawano ◽  
M. Yokoyama ◽  
T. Tsutsui ◽  
M. Yahiro ◽  
...  
Keyword(s):  
Refractive Index ◽  
Glass Substrate ◽  
Silica Aerogel ◽  
Sol Gel ◽  
Supercritical Drying ◽  
Transparent Electrode ◽  
Light Sources ◽  
Photoluminescence Intensity ◽  
Transparent Substrate ◽  
Low Refractive Index

ABSTRACTSilica aerogels prepared by sol-gel methods with supercritical drying process have transparency and extremely low refractive index which is not available in any other materials. This extraordinary refractivity is expected to present some new features as an optical material. Ordinarily, coupling-out efficiency of surface-emissive light sources has been assumed to be low. It is due to the losses organized from internal reflection of emitted light at the air-glass interface and dissipation during wave-guiding propagation within the substrate.However, when material that has extremely low refractive index is inserted between a thin luminescence layer and glass substrate, almost all the light from the luminescence layer can efficiently couple out to air passing through the glass substrate. In this report, we introduce a silica aerogel film as a low refractive index material for surface-emissive devices, such as photoluminescent and electroluminescent device. In the experiments, the photoluminescence intensity of Alq3 through the silica aerogel layer was twice as large as that of the glass substrate without the silica aerogel film. Moreover, we formed a new substrate which contained a transparent electrode on the silica aerogel film. Using this substrate, we fabricated the OLED and observed the disappearance of wave-guiding propagation within the glass substrate.

Effect of the drying on morphology and texture of aerogels and zirconia cryogels

MRS Advances ◽  
2019 ◽  
Vol 4 (64) ◽  
pp. 3513-3521
Author(s):  
Tzipatly A. Esquivel-Castro ◽  
Antonia Martínez-Luévanos ◽  
Luis Alfonso García-Cerda ◽  
Juan C. Contreras-Esquivel ◽  
Pascual Bartolo Pérez ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Cetyltrimethylammonium Bromide ◽  
Sol Gel ◽  
Three Dimensional ◽  
Supercritical Drying ◽  
Sem Images ◽  
Texture Properties ◽  
Dimensional Network ◽  
Zirconia Aerogel

ABSTRACTDue to their excellent properties, aerogel has attracted the attention of the scientific community to use it in the biomedical area as a drug delivery system. This work reports on the synthesis and characterization of ZrO2 aerogels and cryogels obtained by the sol-gel method. The influence of different cetyltrimethylammonium bromide (CTAB) and the type of drying on structural, morphological and texture properties of ZrO2 aerogels and cryogels was investigated. SEM images reveal that a porous interconnected three-dimensional network was formed into aerogels due to supercritical drying. Zirconia aerogel sample has a specific surface area (SBET) larger than zirconia cryogels. Therefore, our results indicate that zirconia aerogel is an adequate material for applications in drug delivery systems.

Preparation and Characterization of Ultralow Density Silica Aerogels by Acetonitrile Supercritical Drying

2012 ◽  
Vol 519 ◽  
pp. 83-86 ◽  
Author(s):  
Guang Wu Liu ◽  
Xing Yuan Ni ◽  
Bin Zhou ◽  
Qiu Jie Yu
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Silica Aerogel ◽  
Sol Gel ◽  
Supercritical Drying ◽  
Silica Aerogels ◽  
High Specific Surface Area ◽  
Molar Ratio ◽  
Sol Gel Process

This paper deals with the synthesis of ultralow density silica aerogels using tetramethyl orthosilicate (TMOS) as the precursor via sol-gel process followed by supercritical drying using acetonitrile solvent extraction. Ultralow density silica aerogels with 6 mg/cc of density was made for the molar ratio by this method. The microstructure and morphology of the ultralow density silica aerogels was characterized by the specific surface area, SBET, SEM, and the pore size distribution techniques. The results show that the ultralow density silica aerogel has the high specific surface area of 812m2/g. Thermal conductivities at desired temperatures were analyzed by the transient plane heat source method. Thermal conductivity coefficients of silica aerogel monoliths changed from 0.024 to 0.043W/ (m K) as temperature increased to 400°C, revealed an excellent heat insulation effect during thermal process.

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.

The Monolithic Silica Aerogel Derived from MTMS/TEOS

2013 ◽  
Vol 364 ◽  
pp. 631-634
Author(s):  
Yu Xi Yu ◽  
Yong Chen
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Silica Aerogel ◽  
Sol Gel ◽  
Supercritical Drying ◽  
Silica Aerogels ◽  
Synthesis And Characterization ◽  
Sol Gel Process

The experimental results on the synthesis and characterization of tetraethoxysilane (TEOS)/ methyltrimethoxysilane (MTMS)-based silica aerogels using two step sol-gel process via supercritical drying, are described. The obtained TEOS/MTMS-based aerogel showed properties of 0.1g/cm3 density, 95.5% porosity and 1070 m2/g specific surface area.

scholarly journals Aerogels in Aerospace: An Overview

2013 ◽  
Vol 2013 ◽  
pp. 1-18 ◽  
Author(s):  
Nadiir Bheekhun ◽  
Abd. Rahim Abu Talib ◽  
Mohd Roshdi Hassan
Keyword(s):  
Silica Aerogel ◽  
Outer Space ◽  
Sol Gel ◽  
Supercritical Drying ◽  
Research Trend ◽  
Sound Waves ◽  
Space Applications ◽  
Sol Gel Process ◽  
Drying Technology ◽  
Highly Porous

Aerogels are highly porous structures prepared via a sol-gel process and supercritical drying technology. Among the classes of aerogels, silica aerogel exhibits the most remarkable physical properties, possessing lower density, thermal conductivity, refractive index, and dielectric constant than any solids. Its acoustical property is such that it can absorb the sound waves reducing speed to 100 m/s compared to 332 m/s for air. However, when it comes to commercialization, the result is not as expected. It seems that mass production, particularly in the aerospace industry, has dawdled behind. This paper highlights the evolution of aerogels in general and discusses the functions and significances of silica aerogel in previous astronautical applications. Future outer-space applications have been proposed as per the current research trend. Finally, the implementation of conventional silica aerogel in aeronautics is argued with an alternative known as Maerogel.

Mechanical and Adiabatic Properties of Silica Aerogel Doped with TiO2 Nanowire

2014 ◽  
Vol 633 ◽  
pp. 336-339
Author(s):  
Zhao Kui Jin ◽  
Xiong Peng ◽  
Hong Yi Gao ◽  
Chao Hao Peng ◽  
Yi Luan
Keyword(s):  
Silica Aerogel ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Nitrogen Adsorption ◽  
Supercritical Drying ◽  
Drying Methods ◽  
X Ray Diffraction ◽  
Static Compression ◽  
Gel Processing

A novel silica aerogel insulation composite was prepared by using TiO2 nanowires as modifier via sol-gel processing and supercritical drying methods in order to address issues of the poor mechanical and the infrared shading performance of silica aerogel. The effects of TiO2 nanowire content on the mechanical and adiabatic performance were investigated by X-Ray diffraction (XRD), nitrogen adsorption (BET), field emission scanning electron microscopy (FESEM), static compression test and thermal analysis. The results show that TiO2 nanowire reinforced aerogels had great thermal insulation properties, while high surface area, low density and mechanical strength were retained.

Comparative studies of Laser induced plasma in TEOS and MTMS based aerogels and solid quartz

MRS Advances ◽  
2017 ◽  
Vol 2 (57) ◽  
pp. 3531-3536 ◽  
Author(s):  
A. Venkateswara Rao ◽  
Channprit Kaur ◽  
A. A. Pisal ◽  
S. Chaurasia ◽  
M. N. Deo ◽  
...  
Keyword(s):  
Silica Aerogel ◽  
Dynamic Pressure ◽  
Laser System ◽  
Sol Gel ◽  
Ammonium Hydroxide ◽  
Supercritical Drying ◽  
X Ray ◽  
Laser Induced Plasma ◽  
Molar Ratios ◽  
Radiation Sources

Abstract:The interaction of laser radiation with low density aerogels is of crucial importance in areas such as the creation of coherent radiation sources in the X-ray range, simulation of astrophysical as well as nuclear fusion phenomena in laboratory and fundamental studies of the properties of soft condensed matter under dynamic pressure in the Mbar range. In the present paper, the experimental results on the X-ray emission of laser induced plasma in TEOS based, MTMS based aerogels and solid quartz targets, are reported. The aerogels were produced by the sol-gel processing of tetraethoxysilane (TEOS) and methyltrimethoxysilane (MTMS) followed by supercritical drying. Silica alcogels were produced using 0.001 M oxalic acid (C2H4O4), 0.5 M ammonium hydroxide (NH4OH) catalysts. Different densities of aerogels varying from 0.02 to 0.06 g/cm3 have been obtained using different molar ratios of TEOS, MTMS, ethanol and catalysts. The laser, with intensity up to 2 x 1014 W/m2, interaction with TEOS and MTMS based aerogels have been conducted using 30J/500 ps Nd : glass laser system. The resulting soft (0.8 – 1.56 Kev) and hard (>4 Kev) X-ray emissions have been measured using semiconductor photodiodes. It has been observed that the soft X-ray yield increases by a factor of two for the silica aerogel targets compared to the X-ray emission from the solid quartz target, whereas the hard X-ray yield reduces. The enhanced soft X-ray yield in silica aerogel targets is attributed to the large volume heating.

scholarly journals Robust Silica–Polyimide Aerogel Blanket for Water-Proof and Flame-Retardant Self-Floating Artificial Island

2021 ◽  
Vol 8 ◽  
Author(s):  
Riyong Liu ◽  
Jin Wang ◽  
Jianhe Liao ◽  
Xuetong Zhang
Keyword(s):  
Thermal Conductivity ◽  
Flame Retardant ◽  
Silica Aerogel ◽  
Ambient Pressure ◽  
Sol Gel ◽  
Three Dimensional ◽  
Ambient Pressure Drying ◽  
Low Density ◽  
Low Thermal Conductivity ◽  
Sol Gel Transition

A robust silica–polyimide (PI) aerogel blanket is designed and synthesized using the PI foam as the matrix and silica aerogel as the filler through an in situ method, where sol–gel transition of silica precursor occurs in pores of the PI foam, followed by the hydrophobization and ambient pressure drying. The density of the aerogel blanket ranges from 0.036 to 0.196 g/cm3, and the low density is directly controlled by tailoring the silica concentration. The specific surface area of the aerogel blanket reaches 728 m2/g. These features of the blanket result in a low thermal conductivity of 0.018 W/mK, which shows a remarkable reduction of 59% compared to that of the PI foam (0.044 W/mK). As a result, a remarkable decrease of 138°C is achieved using the silica blanket as the thermal insulator on a hot plate of approximately 250°C. In addition, the temperature degradation of the blanket is around 500°C, and up to 86% of mass remaining at 900°C is obtained. The blanket is resistant at extremely harsh conditions, e.g., 600°C for 30 min and 1,300°C for 1 min, and no open flame is observed, suggesting a significant flame-retardant of the blanket. Owing to the three-dimensional (3D) porous framework of the PI foam, the silica aerogel is encapsulated in the PI foam and the blanket exhibits strong mechanical property. The silica–PI aerogel can be reversibly compressed for 50 cycles without reduction of strain. The contact angle of the blanket is 153°, which shows a superior waterproof property. Combining with the low density, low thermal conductivity, flame-retardant, and strong mechanical strength, the aerogel blanket has the potential as an artificial island, which is safe (waterproof and flame-retardant), lightweight, comfortable, and easy to be moved.

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