Use Of Aerogel Research Articles

Synthesis of nanocomposites based on Fe3O4 nanoparticles and nitrogen-doped reduced graphene oxide aerogel by ex-situ approach and their magnetic properties

In this study, were synthesised hybrid nanocomposites (Fe3O4@NrGO) using magnetite nanoparticles (Fe3O4-NPs) and nitrogen-doped reduced graphene oxide (NrGO) aerogel through ex-situ approach, which is simple and easily scalable. The NrGO exhibited 7.96 at% N, demonstrated efficient doping and a high content of active nitrogen sites within the composite matrix. Structural, morphological, and elemental analyses of the obtained nanocomposites confirmed the successful incorporation of Fe3O4-NPs into both doped and undoped aerogel matrices (rGO). The presence of nitrogen sites greatly influenced the interaction and incorporation of nanostructures, as evident from the well-distributed and denser nanoparticle arrangement in Fe3O4@NrGO. The impact of matrix doping was also highlighted through porosity analyses, revealing increases in both; pore volume and surface area. Porosity analysis emphasised the efficacy of the ex-situ strategy and the use of aerogel as the matrix, enabling the achievement of a surface area of 1456 m2 g−1 for Fe3O4@NrGO, owing to the particular swelling mechanism of the “spongy” structure. Vibrating-sample magnetometry and electron paramagnetic resonance spectroscopy techniques were employed to investigate the influence of nitrogenous sites on magnetic properties. The higher nanoparticle density in Fe3O4@NrGO resulted in a saturation magnetisation of 0.7219 emu g−1, more than double that of Fe3O4 @rGO. Resonant peaks at low magnetic fields, characterised by a g-factor of 4.4219, were attributed to paramagnetic nitrogen centres that facilitated the efficient anchoring of Fe3O4-NPs in NrGO

RESEARCH OF ENERGY EFFICIENT SOLUTIONS FOR HEAT INSULATION OF CONSTRUCTIONS AND PIPELINES WITH AEROGEL

Ways of energy saving in buildings, namely compliance with the regulatory framework of European standards, possibilities to reduce heat losses during energy transportation through pipelines on the example of heating systems and reducing heat losses during the operation of buildings and structures are studied in the article. It was found that, despite the regular updates of the State Construction Norms of Ukraine, the coefficient of thermal conductivity of insulation materials is not brought into line with generally accepted European standards. The second part of the article presents the results of analytical studies of various thermal insulation materials that are widely used in the territory of Ukraine. After comparing the results, we concluded that the most common at this stage of development of insulation materials will not fully satisfy all the requirements, which must meet all the materials for insulation of structures. The use of some materials is impossible of thermal insulation of structures and pipelines with complex configuration. The solution of energy efficiency along with increasing soundproofing properties, reducing the fire hazard, reducing the load on the bearing structures of buildings and structures is possible through the use of aerogel as a thermal insulation material. The material is characterized by low dependence of the thermal conductivity coefficient on changes in ambient temperature, which makes it the best option for use in harsh operating conditions. After analytical studies of various insulating materials, it was found that aerogel in roll in addition to low coefficient of heat transfer is characterized by better operating properties, namely, non-combustibility of the material, environmental safety, light weight, which reduces the burden on the structure, ease of installation, the possibility of using the structures with high rate of sound insulation.

Low temperature-resistant superhydrophobic and elastic cellulose aerogels derived from seaweed solid waste as efficient oil traps for oil/water separation

Aerogel has excellent application potential in adsorption, heat preservation, and other areas due to its typical advantages of low density and high porosity. However, there are several issues with the use of aerogel in oil/water separation, including weak mechanical qualities and challenges in eliminating organic contaminants at low temperature. Inspired by cellulose Iα, which has excellent performance at low temperature, this study used cellulose Iα nanofibers extracted from seaweed solid waste as the skeleton, through covalent cross-linked with ethylene imine polymer (PEI) and hydrophobic modification of 1, 4-phenyl diisocyanate (MDI), supplemented by freeze-drying technology to form three-dimensional sheet, and successfully obtained cellulose aerogels derived from seaweed solid waste (SWCA). The compression test shows that the maximum compressive stress of SWCA is 61 kPa, and the initial performance still maintains 82% after 40 cryogenic compression cycles. In addition, the contact angles of water and oil on the surface of the SWCA were 153° and 0°, respectively, and the stable hydrophobic time in simulated seawater is more than 3 h. By combining the elasticity and superhydrophobicity/superoleophilicity, the SWCA with an oil absorption capacity of up to 11–30 times its mass, might be utilized repeatedly for the separation of an oil/water mixture.

Analysis of the use of aerogel as a thermal insulator in refrigerated containers for storing blood using a photovoltaic system

At the beginning of the present, a comparative analysis was carried out between polyurethane as a traditional thermal insulator and aerogel as an insulating material that has excellent thermal properties; the analysis is carried out through a container for storing blood, in which calculations of thermal loads were performed. In addition, a photovoltaic system is proposed to supply energy to the container. As a result, the energy consumption of the system is obtained, using the proposed insulators, resulting in lower consumption when aerogel is used.

Aerogel Product Applications for High-Temperature Thermal Insulation

This paper presents the results of theoretical and experimental studies to determine the optimal thickness of thermal insulation from basalt fiber and aerogel products for pipelines at temperatures of 300 and 600 °C. We carried out a comparison of the key thermophysical characteristics of the claimed heat-insulating materials. We performed a thermal imaging survey of the furnace chimney, insulated with basalt fiber and aerogel, while controlling the temperature of the flue gases by establishing the required ratio of the flow rate of natural gas and oxidizer. The temperature gradient along the thickness of the thermal insulation was obtained using a numerical tool developed in ANSYS. The results show that aerogel surpasses basalt fiber in all key thermophysical characteristics. At the same time, the only barrier to widespread industrial production and use of aerogel in the high-temperature thermal insulation segment is its market cost, which is still several times higher than that of basalt fiber in terms of an equivalent performance.

Multilayer Nonwoven Inserts with Aerogel/PCMs for the Improvement of Thermophysiological Comfort in Protective Clothing against the Cold

This study aimed to assess the developed nonwoven inserts with aerogel/PCM (phase change material) microcapsules for use in protective clothing against cold in terms of properties related to thermophysiological comfort. These inserts were obtained by the thermal bonding of a multilayer system consisting of needled-punched nonwovens and silica aerogel particles and/or PCM microcapsules evenly distributed between them. The influence of aerogel and PCM microcapsules on the basic physical properties of inserts, their microstructure, air permeability, and water vapor resistance was investigated and analyzed. The thermal insulation properties of inserts were assessed based on thermal conductivity results. The inserts with PCMs were also tested for their ability to regulate the temperature in the undergarment microclimate using the differential scanning calorimeter (DSC) and the “skin model” device. The research showed that the use of aerogel allowed for reducing the thermal conductivity of the insert by approximately 13% compared to the insert without additives. The high values obtained of the melting and crystallization enthalpy of inserts with PCMs confirmed their high efficiency in the heat absorption and release. Thus, the use of aerogel and PCMs in protective clothing against cold seems to be an effective solution for improving its protective properties and actively adapting its thermal insulation to the changing temperature conditions and the activity level of employees.

Characterization of novel lightweight self-compacting cement composites with incorporated expanded glass, aerogel, zeolite and fly ash

This study is aimed at preparing thermal insulating lightweight self-compacting cement composites (LWSCCC) below the density of 1400 kg/m3 by using lightweight minerals and aggregates. Study results showed that incorporation of porous-structured expanded glass aggregate (EGA) enhances the demand for water to maintain the workability and increases the risk of higher water absorption capacity. The use of a portion of aerogel as a replacement of EGA increases porosity by 7.3%, resulting in lowering of compressive strength by 49% and a 7% increase in water absorption capacity. However, the use of aerogel in combination with EGA cement composite can reach a density of less than 1000 kg/m3, maintaining self-compaction ability and adequate strength. The gaps between the cementitious materials and aerogel shown in SEM indicate poor aerogel particle adhesion with cementitious materials. Additionally, X-ray diffraction analysis and thermal conductivity results were analyzed in this study.

Study on the use of Aerogel on the Surface of Basalt Fabric

Abstract The layer of aerogel was applied to the surface of basalt fabric due to the possibility of improving a fabric protecting against the influence of hot environmental factors. The analysis of aerogel surface roughness and thickness of the obtained sample, resistance to contact heat for the contact temperature between 100°C and 250°C, and tests of resistance to the penetration of thermal radiation were carried out. In addition, thermal conductivity, thermal resistance, thermal diffusion, thermal absorption, and surface roughness were determined. The obtained results indicate the unevenness of aerogel application on the surface of basalt fabric. For this reason, work should be carried out on an appropriate technology that will allow them to be applied evenly on the surface of the fabric. The parameters tested and the results obtained are promising in terms of the possibility of using the fabric obtained in protective gloves.

Aerogel nonwoven as reinforcement and batting material for firefighter’s protective clothing: a comparative study

Aerogel, the most insulated solid known to modern science, is gradually expanding its field of application from space shuttle to normal clothing. So far, apparel use of aerogel nonwoven has been successfully commercialized in case of cold weather clothing. Use of aerogel in high heat protective clothing is much complex as it requires to balance comfort with protection. This paper studied the protective performance of aerogel nonwoven in a high heat protective apparel, firefighter’s protective clothing (FPC). An investigation was carried out to justify its use as reinforcement material and/or batting in thermal liner or moisture barrier of FPC. Impressive results were observed in case of reducing the risk of burn injury, increasing comfort and enhancing protection. It was observed that aerogel nonwoven can provide eight times more thermal resistance than existing commercial reinforcement material and existing thermal batting material. When the aerogel nonwoven layer was used as thermal liner, it offered five times more resistance to heat than existing thermal liner and three times more resistance than combined performance of existing thermal liner and moisture barrier. The possible burn injury under 49 N compressive load was predicted on a 200 °C heated surface. It was found that the temperature behind the commercial reinforcement material quickly raised above 70 °C within 30 s of contact, while it took more than 4 min to reach the same temperature for proposed aerogel reinforcement material. This indicates that a firefighter will receive instant burn on contact in 30 s if only the commercial reinforcement material is used. It was measured that, without any reinforcement material even when only the aerogel nonwoven is used instead of current batting material, a firefighter will have 86 s before feeling any pain, 107 s before receiving first-degree burn and will have 2 and half minutes before theoretically receiving second-degree burn at the same condition. Thus, a firefighter will gain more than 1 min of escape time to withdraw from a danger situation, where it is only 5 s for existing thermal liner and reinforcement material. Performance was also evaluated against fabric thickness and weight, air permeability, resistance to one-way liquid transfer, moisture management, moisture vapour transfer and degree of evaporative cooling. The advantages and disadvantages of proposed combination have been discussed and it was concluded that the use of aerogel reinforcement can significantly increase the protective performance of FPC. Aerogel nonwoven (A) showed superior performance over existing reinforcement material (Rinf) and thermal liner (F+B1) for firefighter’s protective clothing. In particular, aerogel nonwoven has

Sound Transmission Loss Enhancement in an Inorganic‐Organic Laminated Wall Panel Using Multifunctional Low‐Density Nanoporous Polyurea Aerogels: Experiment and Modeling

Recently, the authors have reported an exceptional normal incidence sound transmission loss characteristic for a class of low density, highly porous, and mechanically strong polyurea aerogels. Herein, a laminated composite comprising the organic low‐density aerogels bonded with an inorganic compound (e.g., gypsum materials) is considered to investigate the constrained damping effects of the aerogels on the airborne sound insulation behavior of the composite using the standard chamber‐based diffuse sound field measurements. Huge improvement in the sound transmission loss is obtained due to the use of aerogel without a significant increase in the overall weight and thickness of the composite panel (e.g., more than 10 dB increase by reaching 40 dB sound transmission loss at 2 kHz after the implementation of only two 5 mm‐thick aerogel layers at bulk densities 0.15 and 0.25 g cm−3). This uncommon behavior breaks the empirical “Mass Law” nature of the most conventional acoustic materials. In addition, an exact analytical time‐harmonic plane‐strain solution for the diffused wave propagation through the multilayered structure is provided using theories of linear elasticity and Biot's dynamic poroelasticity. The theoretical results are well supported by the experiments which can be utilized for the design of the future light‐weight multifunctional composite structures.

Synthesis and characterization of silica aerogel as a promising drug carrier system

In the past years, use of aerogel in drug carrier systems has been of great interest among researchers because of its amorphous structure, significant porosity, and other special properties. In this study, the effects of physical characteristics of silica aerogels on the efficient medical application are investigated. To this end, silica aerogels with several densities were synthesized by using a two-stage sol-gel procedure and dilution by acetonitrile in gelation step. Physical characteristics of produced silica aerogels were analyzed by BET and BJH methods. Results reveal that the pore diameter and the surface area of silica aerogel are functions of its density. Using supercritical CO2 method, the efficiency of drug (Ketoprofen) loading on aerogels with respect to aerogel density was investigated. Cell viability and cell growth on silica aerogels were evaluated by MTT assay and SEM analysis, respectively. The drug-loaded materials were characterized by using of FT-IR, XRD, UV-Spectroscopy, and FE-SEM analysis. Results show that the effective density of silica aerogel for a drug carrier system is 0.12 g/cm3.

The thermal protection and comfort properties of aerogel and PCM-coated fabric for firefighter garment

The study evaluates the simultaneous use of aerogel and phase change material (PCM) on the face cloth of thermal liner in firefighter’s protective garment. Aerogel is commonly used to resist incoming heat flux in the field of high heat protection and to prevent the loss of body heat in the cold environment clothing. In high heat protection clothing, aerogel not only resists the incoming heat fluxes but also blocks the outbound body heat. As a result the wearer suffers from internal increase of body temperature. Previous studies identified the potential use of aerogel in firefighter’s protective clothing. However there was no clear approach to resolve the problem associated with body heat release. Current study focuses on the problem by applying PCM along with aerogel on fabric. The ambient-side of a thermal liner face cloth was coated with silica aerogel particles; meanwhile, the next to skin side was coated with PCM/aerogel composite powder. The new thermal liner revealed superior thermal protection and comfort. It extended the time to reach pain threshold and increased the pain alarm time. The Fourier transform infrared analysis of the aerogel/PCM composite powder showed the presence of PCM in nanoporous aerogel particles while the differential scanning calorimeter quantified the heat absorbing capacity of the new composite powder. Scanning electron microscope, air permeability tester, and jPOR macro of ImageJ software were used for the surface characteristics and porosity analysis of coated liner. The thermal stability of the composite powder was investigated through an infrared thermal camera. No dripping or form deterioration was observed when the composite powder was heated over a temperature three times above the melting temperature of the pure PCM.

Aerogel: Space exploration applications

The unique physical properties of aerogel have proven to be enabling to a variety of both flight and proposed space exploration missions. The extremely low density and highly porous nature of aerogel makes it suitable for stopping high velocity particles, as a highly efficient thermal barrier, and as a porous medium for the containment of cryogenic fluids. The use of silica aerogel as a hypervelocity particle capture and return media for the Stardust Mission has drawn the attention of many in the space exploration community. Aerogel is currently being used as the thermal insulation material in the 2003 Mars Exploration Rovers. The SCIM (Sample Collection for the Investigation of Mars) and the STEP (Satellite Test of the Equivalence Principle) Missions are both proposed space exploration missions, in which, the use of aerogel is critical to their overall design and success. Composite materials comprised of silica aerogel and oxide powders are under development for use in a new generation of thermoelectric devices that are planned for use in many future space exploration mission designs. Work is currently ongoing in the development and production of non-silicate and composite aerogels to extend the range of useful applications envisioned for aerogel in future space exploration projects.

Using Silica Aerogel to Characterize Hypervelocity Shrapnel Produced in High Power Laser Experiments

We present a technique using silica aerogel to characterize the number, velocity, size, and spatial distribution of shrapnel. Measuring shrapnel produced in a large laser facility can aid in improving target designs to reduce shrapnel, thereby extending optics lifetime. We tested the use of aerogel as a diagnostic by creating shrapnel on the Helen Laser at AWE in England and capturing it in prepositioned 20 mg/cc silica aerogel-filled holders placed from 10 to 50 cm away. Synchrotron radiation at the Stanford Linear Accelerator was used to produce radiographic images of the embedded shrapnel at three different angles. The contrast for 19 keV x-rays for Ta and aerogel allowed very fine resolution of the Ta particles, down to ∼ 5 microns diameter. Reconstruction of the data resolved each particle's depth and size. We developed an expression that relates particle size and depth of penetration to incident velocity assuming the particle acts like a 'snowplow' into the aerogel where the dominant energy loss is dissipation into viscous drag. The aerogel data is being used to validate and tune hydrodynamic modeling of the target break-up. We also tested a more complex technique of the use of aerogel to characterize shrapnel that uses a thin sheet of aerogel over a fused silica substrate. We conclude that these techniques may be viable for measuring solid shrapnel, droplets, and even condensed vapor with sufficient resolution to quantify their asymmetric deposition within the target chamber.

Liquid helium motion and confinement for a cryogenic gravimetric mission

Within the Gravity Field and Ocean Circulation Explorer (GOCE) mission of the European Space Agency, we are performing a detailed comparison between the expected performances of a superconducting gravity gradiometer to be operated at T ∼ 2K and an electrostatic one to be operated at room temperature. As part of this analysis we have evaluated the gravitational perturbation due to liquid helium motion for the cryogenic instrument and proposed a possible method of helium confinement based on the use of aerogel.

The HERMES dual-radiator ring imaging Cherenkov detector

The construction and use of a dual radiator Ring Imaging Cherenkov (RICH) detector is described. This instrument was developed for the HERMES experiment at DESY which emphasises measurements of semi-inclusive deep-inelastic scattering. It provides particle identification for pions, kaons, and protons in the momentum range from 2 to 15 GeV , which is essential to these studies. The instrument uses two radiators, C 4F 10, a heavy fluorocarbon gas, and a wall of silica aerogel tiles. The use of aerogel in a RICH detector has only recently become possible with the development of clear, large, homogeneous and hydrophobic aerogel. A lightweight mirror was constructed using a newly perfected technique to make resin-coated carbon-fiber surfaces of optical quality. The photon detector consists of 1934 photomultiplier tubes (PMT) for each detector half, held in a soft steel matrix to provide shielding against the residual field of the main spectrometer magnet.

Effect of gravity on helium II in aerogel

We have observed for aerogel nearly filled with superfluid helium that the helium II liquid-vapour interface in the aerogel takes a shape that does not change with respect to gravity (the longest time studied was 3 hr.). the most likely reason we observe a fixed helium II liquid-vapour interface is due to the presence of capillary forces. We have concentrated our studies on the serogel nearly filled with superfluid helium since this is when capillary forces are weakest and least understood. The distribution of helium II in the aerogel is subsequently most susceptible to gravity. We conclude that the helium II liquid-vapour interface will not change shape due to gravitational forces of 1 g for any amount of helium in the aerogel. This makes aerogel a very promising candidate for gravitational missions such as STEP (Satellite Test of the Equivalence Principle) or GOCE (Gravity Field and Ocean Circulation Explorer) that are susceptible to helium II motion. In the case of STEP, gravity gradient forces of magnitude 10 −7 g act on the superfluid helium at twice orbital frequency. The motion of helium II produces a gravitational signal in the bandwidth of the STEP measurement. The use of aerogel would eliminate this signal. Thus, trying to isolate this signal by experimental procedure or data analysis is no longer necessary.

Ring-imaging Cherenkov detectors for LHC-B

The particle identification system proposed for the LHC-B experiment is presented. It consists of ring-imaging Cherenkov detectors with three radiator materials, including the novel use of aerogel in an imaging detector. High performance photodetectors are under development, utilizing multipixel hybrid photodiodes. Significant π K separation will be possible for isolated tracks with momenta between 1 and 150 GeV/ c. The first studies of pattern recognition in regions of high track density are described.

Use of aerogel for imaging Cherenkov counters

In the past, detectors using silica aerogel as a Cherenkov radiator treated this material as a diffuse source of Cherenkov photons. In this paper we report on measurements made to explore the feasibility of using aerogel for imaging Cherenkov purposes. The results of the measurements are reproduced by a detailed Monte Carlo. This allows us to identify parameters critical for the use of aerogel as a radiator in imaging detectors. We conclude that commercially available aerogel can be used for these purposes.