Preparation of silica aerogel

Overview of aerogel SiO2

English aerogel, also known as xerogel. When most of the solvent is removed from the gel, the liquid content in the gel is much less than the solid content, or the medium in the spatial network structure of the gel is gas and the appearance is solid. This is a dry gel. It is called aerogel. Aerogel is a solid material form, the smallest solid in the world, with a density of 3kg per cubic meter. The common aerogel is silicon aerogel, which was first proposed by American scientist Kistler in 1931. There are many types of aerogels, including silicon, carbon, sulfur, metal oxides, and metals. Aerogel is a compound word, in which aero is an adjective, meaning to fly, and gel is obviously a gel. Literally means flying gel. A gel of any substance can be called an aerogel as long as it can be dried to remove the internal solvent.

Due to its extremely low density, currently the lightest silica aerogel is only 0.16 mg per cubic centimeter, which is slightly lower than the density of air, so it is also called "frozen smoke" or "blue smoke." Since the particles inside are small (nano-scale), visible light scatters less when passing through it (Rayleigh scattering), just like sunlight passes through the air. Therefore, it looks like the sky (if there is no mixing) and looks blue. If it looks at the light, it will be a bit red. (The sky is blue and the sun looks a bit red). Since more than 80% of the aerogel is air, it has a very good thermal insulation effect. One inch of aerogel is equivalent to the insulation function of 20-30 pieces of ordinary glass. Even if the aerogel is placed between the rose and the flame, the rose will be intact. Aerogels also have many uses in space exploration. It is used in the Russian Mir space station and the US Mars Pathfinder probe. Aerogel is also used as a detector for the Cherenkov effect in particle physics experiments. A particle discriminator called the Aerogel Cherenkov Counter (ACC) in the Belle Experimental Detector of the High Energy Accelerator Institute B Meson Factory is a recent application example. The aerogel used in the detector has low refractive index characteristics between liquid and gas, as well as its high light transmittance and solid properties, which are superior to traditional methods using cryogenic liquid or high-pressure air. At the same time, its lightweight nature is also one of the advantages. It is used in the Russian Mir space station and the US Mars Pathfinder probe. Aerogel is also used as a detector for the Cherenkov effect in particle physics experiments. A particle discriminator called the Aerogel Cherenkov Counter (ACC) in the Belle Experimental Detector of the High Energy Accelerator Institute B Meson Factory is a recent application example. The aerogel used in the detector has low refractive index characteristics between liquid and gas, as well as its high light transmittance and solid properties, which are superior to traditional methods using cryogenic liquid or high-pressure air. At the same time, its lightweight nature is also one of the advantages. It is used in the Russian Mir space station and the US Mars Pathfinder probe. Aerogel is also used as a detector for the Cherenkov effect in particle physics experiments. A particle discriminator called the Aerogel Cherenkov Counter (ACC) in the Belle Experimental Detector of the High Energy Accelerator Institute B Meson Factory is a recent application example. The aerogel used in the detector has low refractive index characteristics between liquid and gas, as well as its high light transmittance and solid properties, which are superior to traditional methods using cryogenic liquid or high-pressure air. At the same time, its lightweight nature is also one of the advantages. Aerogel is also used as a detector for the Cherenkov effect in particle physics experiments. A particle discriminator called the Aerogel Cherenkov Counter (ACC) in the Belle Experimental Detector of the High Energy Accelerator Institute B Meson Factory is a recent application example. The aerogel used in the detector has low refractive index characteristics between liquid and gas, as well as its high light transmittance and solid properties, which are superior to traditional methods using cryogenic liquid or high-pressure air. At the same time, its lightweight nature is also one of the advantages. Aerogel is also used as a detector for the Cherenkov effect in particle physics experiments. A particle discriminator called the Aerogel Cherenkov Counter (ACC) in the Belle Experimental Detector of the High Energy Accelerator Institute B Meson Factory is a recent application example. The aerogel used in the detector has low refractive index characteristics between liquid and gas, as well as its high light transmittance and solid properties, which are superior to traditional methods using cryogenic liquid or high-pressure air. At the same time, its lightweight nature is also one of the advantages.

Preparation of silica aerogel

Aerogel refers to a nano-porous solid material formed by using a sol-gel method, using a certain drying method, and replacing the liquid phase in the gel with gas. Such as gelatin, gum arabic, silicone aerogel, hair, nails, etc. Aerogel also has the characteristics of gel, that is, it has swelling, thixotropy, and desizing effects.

Aerogel is a form of solid matter, the smallest dense solid in the world. The density is 3 kilograms per cubic meter. A common aerogel is silicon aerogel. There are many types of aerogels, including silicon, carbon, sulfur, metal oxides, and metals. Aerogel is a compound word, in which aero is an adjective, meaning flying, and gel is obviously gel. Literally means flying gel. As long as the gel of any substance can be dried to remove the internal solvent, but can basically keep its shape unchanged, the product has high porosity and low density, it can be called aerogel.

Aerogels were originally named by S. Kistler. Because he successfully prepared silica aerogel by supercritical drying method, he defined aerogel as a substance obtained by supercritical drying of wet gel, called aerogel. In the mid to late 1990s, with the emergence and development of atmospheric drying technology, the generally accepted definition of aerogel in the mid to late 1990s is: no matter what drying method is used, as long as the liquid in the wet gel is absorbed, it can be replaced by gas, although The network structure of the gel remains basically unchanged, but the resulting materials are all called aerogels. The structural feature of aerogel is a cylindrical multi-branched nanoporous three-position network structure with high permeability, extremely high porosity, extremely low density, high specific surface area and ultra-high pore volume. Its bulk density is adjustable in the range of 0.003-0.500 g/cm-3.

The preparation of aerogel usually consists of a sol-gel process and a supercritical drying process. In the sol-gel process, by controlling the hydrolysis and polycondensation reaction conditions of the solution, nanoclusters of different structures are formed in the solution, and the clusters adhere to each other to form a gel, and after a full chemical reaction around the solid skeleton of the gel Remaining liquid reagent. In order to prevent the surface tension in the micropores from damaging the material structure during the gel drying process, the gel is processed by a supercritical drying process, the gel is placed in a pressure vessel, and the temperature and pressure are increased to change the liquid in the gel. As a supercritical fluid, the gas-liquid interface disappears and the surface tension no longer exists. At this time, the supercritical fluid is released from the pressure vessel, and a porous, disordered, low-density gas with a nano-scale continuous network structure can be obtained. Material gel.

Aerogel SiO2 application

In the study of fractal structure, silicon aerogel is a nanoporous material with a controllable structure, and its density obviously depends on the size of the scale. Within a certain scale, its density tends to be the same, that is, the density increases with the scale, and has a self-similar structure. The structure in the dynamic research of aerogel fractal structure also shows that there is a significant dispersion relationship at different scales The three different excitation regions correspond to the excitation of phonons, fractals and particles. Changing the preparation conditions of aerogels can change the correlation length within two orders of magnitude. Therefore, silica aerogel has become the best material for studying the fractal structure and its dynamic behavior.

Engaged in "863" high-tech high-power laser research. Nanoporous materials have important application value. For example, using a porous target with a density lower than the critical density can improve the beam quality of the X-ray laser generated by electron collision excitation, save driving energy, and use a new type of porous target with a microsphere node structure. The cooling of the three-dimensional adiabatic expansion of the plasma increases the gain coefficient of the X-ray laser generated by the electronic recombination mechanism. The use of ultra-low density materials to adsorb nuclear fuel can form a high-gain cryo target for laser inertial confinement fusion. Aerogel’s slender nanoporous network structure, huge specific surface area,

As a thermal insulation material, the slender nano-network structure of silicon aerogel effectively limits the propagation of local thermal excitation, and its solid-state thermal conductivity is 2-3 orders of magnitude lower than that of corresponding glass materials. -The pores suppress the contribution of gas molecules to heat conduction. The refractive index of silica aerogel is close to 1, and the annihilation coefficient ratio to infrared and visible light is greater than 100. It can effectively transmit sunlight and prevent infrared heat radiation at room temperature, making it an ideal transparent thermal insulation material, which has been used in solar energy utilization and building energy conservation. The doping can further reduce the radiant heat conduction of the silicon aerogel. The thermal conductivity of carbon-doped aerogel can be as low as 0.013w/m·K at normal temperature and pressure. It is currently the solid material with the lowest thermal conductivity and is expected to replace polyurethane foam as a new type of refrigerator insulation material. Doping with titanium dioxide can make silicon aerogel Become a new type of high temperature insulation material. The thermal conductivity at 800K is only 0.03w/m·K, which will be further developed as a new material for military products. Doping with titanium dioxide can make silicon aerogel a new type of high-temperature thermal insulation material. The thermal conductivity at 800K is only 0.03w/m·K, which will be further developed into a new material for military products. Doping with titanium dioxide can make silicon aerogel a new type of high-temperature thermal insulation material. The thermal conductivity at 800K is only 0.03w/m·K, which will be further developed into a new material for military products.

Due to its low sound velocity, silicon aerogel is also an ideal sound delay or high-temperature sound insulation material. This material has a large acoustic impedance variable range (103-107 kg/m2·s), and is an ideal acoustic resistance coupling material for ultrasonic detectors. For example, the commonly used piezoelectric ceramics with acoustic resistance change Zp=1. 5×l07 kg/m2·s are used as ultrasonic generators and detectors, while the acoustic resistance of air is only 400 kg/m2·s. Silicon aerogel with a thickness of 1/4 wavelength is used as an acoustic resistance coupling material between piezoelectric ceramics and air. It can improve the transmission efficiency of sound waves and reduce the signal-to-noise ratio in equipment applications. Preliminary experimental results show that silica aerogel with a density of about 300 kg/m3 as a coupling material can increase the sound intensity by 30 dB. If a silica aerogel with a density gradient is used, it is expected that a higher sound intensity gain will be obtained.

In the fields of environmental protection and chemical engineering, nano-structured aerogels can also be used as a new type of gas filtration. The difference from other materials is that the material has uniform pore size distribution and high porosity, which is an efficient gas filter material. Because the material is particularly larger than watch products. Aerogel also has broad application prospects as a new type of catalyst or catalyst carrier.

In terms of energy storage devices, organic aerogels are processed by a sintering process to obtain carbon aerogels. This conductive porous material is a new type of carbon material developed after fibrous activated carbon. It has a large specific surface area (600-1000 square meters). /kg) and high conductivity (10-25 s/cm). And head. The density range is very wide (0.05-1.0 g/cm3). If the micropores are filled with appropriate electrolyte, a new type of rechargeable battery can be manufactured. It has excellent characteristics such as large storage capacity, small internal resistance, light weight, strong charge and discharge capacity, and reusability. Preliminary experimental results show that the charging capacity of the carbon aerogel is 3×104/kg2, the power density is 7 kw/kg, and the repeated charge and discharge performance is good.

In the study of the quantum size effect of materials. Due to the formation of quantum dot structure in the silicon aerogel nano-network, the results of chemical vapor infiltration method doping Si and solution method doping C60 indicate that the dopant exists in the form of nanocrystalline particles, and strong visible light emission is observed. It provides strong evidence for the quantum confinement effect of porous silicon luminescence. Using the structure of silicon aerogel and the nonlinear optical effect of C60, new laser protective glasses can be further developed. The doping method is also an effective way to form nanocomposite phase materials.

In addition, silica aerogel is a material with adjustable refractive index. Using different densities of aerogel media as Cerenkov threshold detectors can determine the mass and energy of high-energy particles. Since high-speed particles can easily penetrate porous materials and gradually slow down to achieve a "soft landing", if a transparent aerogel is used to capture high-speed particles in space, the blocked and captured particles can be observed with the naked eye or a microscope.

As a new type of nanoporous material, in addition to silicon aerogels, binary or multiple oxide aerogels, organic aerogels and carbon aerogels have also been developed. New materials, such as the preparation of porous silicon with extremely high porosity, the preparation of high-performance catalysts for metal-aerogel hybrid materials, high-temperature superconducting materials, and ultrafine ceramic powders. At present, the international research work of aerogel materials is mainly concentrated in the University of Würzburg in Germany, BASF, Lorenz Livermore National Laboratory, Sandia National Laboratory, and Montpellier Material Research Center in France , Japan's National Laboratory for High Energy Physics, and domestically mainly concentrated in Tongji University, National University of Defense Technology, Tsinghua University, Tongji University, Zhejiang Shaoxing Nano Technology Co., Ltd. and Guangdong Allison High-Tech Co., Ltd. The spherical solid physics laboratory. Also Guangdong Aili Mori Technology Co., Ltd. is currently the largest manufacturer of aerogel products in China.

Fold other uses

1. Make Mars Expedition Spacesuit

In 2002, NASA established a company specializing in the production of stronger and more elastic aerogels. NASA has now determined that during the 2018 Mars expedition, astronauts will wear spacesuits made of a new type of aerogel. The company's senior scientist Mark Krajevsky said that as long as an 18 mm thick aerogel layer is added to the spacesuit, it can help astronauts withstand the high temperature of 1300 ℃ and the ultra-low temperature of minus 130 ℃. "This is the most effective thermostatic material I have ever seen." Mark said.

2. Bulletproof is not afraid of being bombed

Bulletproof is the second important use of new aerogels. NASA is testing houses and military vehicles built with aerogel. According to laboratory tests, if a layer of aerogel of about 6mm thickness is added to the metal sheet, the metal sheet will not be damaged even if the explosive explodes directly.

3. Able to respond to ecological disasters

Environmental protection is the third important role of the new aerogel. Scientists affectionately call aerogel a "super sponge" because it has millions of small pores on its surface and is an ideal material for adsorbing pollutants in water. The aerogel newly invented by American scientists can now absorb lead and mercury in water. According to scientists, this aerogel is an excellent material for responding to ecological disasters. For example, after the sinking of the "Sea Express" tanker in 1996, 72,000 tons of crude oil leaked. If this material were used at that time, it would not cause serious pollution to the entire coast.

4. The tennis racket has a stronger ability to hit the ball

In the future, new aerogels will also enter the daily lives of each of us. For example, Dunlop Sports Equipment in the United States has successfully developed a tennis racket containing aerogel. It is said that this tennis racket has a stronger ability to hit the ball. At the beginning of this year, the 66-year-old Bob Stoker became the first Englishman to use aerogel to build a house: "The effect of heat preservation and heating is very good. I will use the air conditioner to lower the temperature by 5°C. As a result, the indoor temperature is still very comfortable." Climbers are also hopeful about the use of aerogel. The shoes worn by British climber Anne Parment when he climbed Mount Everest last year used some aerogel materials, and there was a layer of this new material in his sleeping bag.

Aerogel SiO2 price

The price of aerogel SiO2 varies randomly with factors such as the production cost of aerogel SiO2, transportation costs, international conditions, exchange rates, and the relationship between supply and demand in the aerogel SiO2 market. Tanki New Materials Co., Ltd. aims to help various industries and chemical wholesalers find high-quality, low-cost nanomaterials and chemicals by providing a full set of customized services. If you are looking for aerogel SiO2, please feel free to send an email to get the latest aerogel SiO2 price.

Suppliers of Aerogel SiO2

As a global aerogel supplier, Tanki New Materials Co., Ltd. has extensive experience in the performance, application and cost-effective manufacturing of advanced engineering materials. The company has successfully developed a series of powder materials (including boron carbide, aluminum carbide, titanium carbide, etc.), high-purity targets, functional ceramics and structural devices, and provides OEM services.