Included in the "Classification of Strategic Emerging Industries", aerogel will usher in an explosion
Recently, the National Bureau of Statistics released the "Classification of Strategic Emerging Industries (2018)". As one of the materials in the field of sound insulation and heat insulation material manufacturing, aerogel and its products have entered this classification catalog for the first time. The document issued by the National Bureau of Statistics clearly pointed out that the purpose of formulating this classification is to accurately reflect the development plan of national strategic emerging industries during the 13th Five-Year Plan period, and to meet the statistical needs of measuring the scale, structure and speed of the development of strategic emerging industries. This means that products and services that can be listed in this document, such as aerogels and their products, are all "strategic emerging industries" recognized by authoritative organizations such as the National Bureau of Statistics. Strategic emerging industries are based on major cutting-edge technological breakthroughs, representing the new direction of future technology and industrial development, reflecting the development trend of knowledge economy, circular economy, and low-carbon economy in the world today. They are still in the early stages of growth and have great potential for future development. An industry that has an overall driving force and a major leading role in the economy and society.
Since ten years ago, my country has always attached great importance to the development and planning of "strategic emerging industries". In 2009, the State Council held the first symposium on the development of strategic emerging industries. The "Strategic Emerging Industries" development plan launched in 2010 framed seven strategic emerging industry development goals in the form of an executive meeting of the State Council. In 2012, the executive meeting of the State Council discussed and approved the "Twelfth Five-Year" National Strategic Emerging Industry Development Plan, which further clarified the key development directions and main tasks of the seven strategic emerging industries. So far, vigorously develop strategic emerging industries. To the "real place". In 2016, the State Council issued the "Thirteenth Five-Year" National Strategic Emerging Industry Development Plan. The plan pointed out that during the 13th Five-Year Plan period, strategic emerging industries should be placed in a more prominent position in economic and social development, and modern The new industrial system promotes sustained and healthy economic and social development. In early 2017, the National Development and Reform Commission issued the "Guiding Catalog for Key Products and Services of Strategic Emerging Industries". The catalog is divided into 8 industries in 5 major areas of strategic emerging industries such as new generation information technology, high-end equipment manufacturing, new materials, biology, new energy, and digital creativity. At the end of 2018, the National Bureau of Statistics released the "Classification of Strategic Emerging Industries (2018)", including: a new generation of information technology industry, high-end equipment manufacturing industry, new material industry, biological industry, new energy automobile industry, new energy industry, energy conservation and environmental protection industry , Digital creative industries, and related service industries.
What are the special advantages of new aerogels
Aerogel, as the lightest solid in the world, has been favored by many scientists over the years. Recently, scientists have developed a new aerogel—air alloy. This raw material has high strength, durability, Features such as ultra-light weight and planability. The most important thing is that this material has a super-insulating function, which has special meaning for the development of thermal insulation materials and the field of aerospace.
The most used raw material in the world may be here, and it will change everything. Aerogel has been around for a while, but innovation has made aerogel skills more perfect and more useful. Aerogel is a low-density solid raw material, which can be obtained by extracting liquid from colloid through supercritical drying process. The common aerogel is silicon aerogel, but this material is very brittle. Through years of research, scientists from the National Aeronautics and Space Administration (NASA) and some companies have developed a new product-air alloy.
This air alloy not only has the high strength and durability of traditional plastics, but also has the characteristics of light weight, and the super insulation function found in aerogel is the biggest advantage of this product. Part of the reason why this material is so promising is that it is super planable. Air alloys have extremely low density (0.01~0.9g/cm2), which makes them the lightest solid raw materials on earth. In addition to this low-density characteristic, this material also has super-insulating function and extreme material strength. The polymer raw materials based on this air alloy can bear 20,000 times more than their own weight.
The super-insulating property of this material makes scientists extremely shocked, which gradually makes thin and light insulating materials possible. The raw material not only can block temperature, but also has a good effect on blocking sound. In fact, as an acoustic insulator, this material is 100 to 1000 times better than other products on the market. Recently, the National Aeronautics and Space Administration (NASA) has developed an ultra-thin and flexible air alloy (as shown below), which is used abundantly in space suits and rocket technology.
The mechanical and structural functions of this material are gradually moving forward, and it can even be made into a transparent one that allows sunlight to enter, but it will certainly not affect the thermal insulation function. The future of this material will be grasped by engineers and planners who are constantly working to discover more uses for the material. Many aerogel commercial companies have also been established, and there will even be a company that uses an improved version of aerogel to make high-quality jackets.
What is the thermal insulation principle of aerogel thermal insulation materials
Aerogels, also known as xerogels, have a density of only 2.75 times the density of air, making it the densest solid in the world. Aerogels can be divided into carbon series, silicon series, sulfur series, metal oxide series, metal series, etc. according to their composition. However, nowadays, silicon aerogels-silica aerogels are more developed and used.
Aerogel is a new type of lightweight nanoporous product. It has a nanostructure (typical pore size is less than 50nm, framework particles are 1-20nm), large specific surface area (up to 800-1000㎡/g), and high porosity ( It can be as high as 80%-99.8%) and other characteristics. Generally, the structure and function of aerogels do not change significantly at 800°C. Therefore, aerogels have unparalleled advantages as high-temperature insulation products.
Insulation principle of aerogel insulation products
(1) Convection: When the diameter of the pores in the aerogel is less than 70nm, the air molecules in the pores lose their ability to move freely and are relatively attached to the pore walls. At this time, the product is in an approximate vacuum state.
(2) Radiation: Because the pores in the aerogel are all nano-sized pores and the product itself has a very low volume density, the number of pore walls inside the product tends to be "infinitely large", and each pore wall is covered. The effect of the hot plate is therefore close to the "infinite number of heat shields" effect, which reduces the radiant heat transfer to almost the lowest limit.
(3) Heat conduction: Because of the nearly infinite number of nanopores, the heat flow in the solid can only be transferred along the pore walls. The nearly infinite number of pore walls constitutes a nearly "infinite path" effect, which makes the solid heat conduction In order to drop to the lowest limit.
Compared with traditional thermal insulation products, nanoporous aerogel thermal insulation products can achieve equivalent thermal insulation effects with lighter weight and smaller volume. It has good thermal stability, thermal shock resistance and thermal insulation, which can replace traditional mineral wool, so that the house can be insulated and warm. If it is used in high-rise buildings, it can replace general curtain wall glass, greatly reduce the weight of the building, and can play a fire prevention effect. In addition, replacing traditional thermal insulation products with aerogel thermal insulation composite products on the top of pipelines, furnaces and other thermal equipment can greatly reduce heat loss. Applying nanoporous super insulation product aerogel to the storage tanks, pipes and collectors of solar water heaters, the heat collection efficiency can be increased by more than one time, and the heat loss will be reduced to less than 30% of the current level. In addition, before and after use, it can insist on not powdering, not brittle, not aging, and not supporting the growth of mold, and the induction function will remain unchanged for a long time; the service life is long, and the life span of the building can be maintained.
The practical application of aerogel starts from the aerospace field
Aerogels have multiple functions and are widely used. For example, aerogels can be used in environmental protection by taking advantage of their multi-surface specific area and strong adsorption capacity; using their porous, shock-absorbing and anti-vibration characteristics, they can be used for explosion-proof and energy-absorbing requirements; using aerogel materials for super It has the characteristics of light insulation, and it is used in mountaineering clothing and other fields.
The practical use of aerogel started from the aerospace category. On the Russian "Peace" space station and the US "Mars Pathfinder" probe, aerogel materials are used for thermal insulation. The aerogel materials can withstand temperatures from -196 to 1400 degrees Celsius, and because of their extremely low thermal conductivity, It can ensure the normal operation of the detector under extreme temperatures. NASA’s "Stardust" spacecraft also uses aerogel to collect comet dust. The porous size of the aerogel and its extremely light weight make the aerogel look like a soft baseball glove, and then let the comet fly at high speed. The dust stopped after running for a while.
Up to now, the most widely used aerogel material is its excellent thermal insulation function. With aerogel composite insulation felt as the main product, aerogel materials have a wide range of applications in industrial pipe networks and kilns, petrochemical equipment, construction, cryogenic equipment, and cold insulation. Aerogel composite thermal insulation felt has the advantages of good thermal insulation, A-level fire protection, high hydrophobicity, and long service life. It sits on the top of the pyramid of thermal insulation materials with absolute advantages.
The development prospects of aerogel products in construction and industry
As power shortages and environmental pollution have become hot issues of global importance, benefiting from the country’s strong support for energy conservation and environmental protection and the continuous deepening of urbanization, aerogel products, as an excellent energy-saving and environmentally friendly product, usher in It's development opportunities.
The five development concepts of "innovation, harmony, greenness, openness, and sharing" put forward by the Fifth Plenary Session of the Eighteenth Central Committee of the Communist Party of China first are to deepen and promote the development of technological innovation. Aerogel is listed as one of the ten most sought-after sciences and technologies, and is known as the "magic material that can change the world." In 2014 and 2015, the National Development and Reform Commission listed aerogel materials in the "National Key Energy-saving and Low-Carbon Technology Promotion Catalog" for two consecutive years, and started the promotion and application of aerogel materials. Let's take construction and industrial pipe networks as examples to analyze the development prospects of aerogel products.
Within the scope of the building, the energy consumption of the building accounts for about 30% of the total energy consumption of the whole society, and this “30%” is only the energy consumption during the construction and use of the building. The energy lost (accounting for 16.7% of the total energy consumption of the whole society), and the energy consumption related to buildings will account for 46.7% of the total energy consumption of the society. In 2020, my country's building energy consumption will reach 2,943 billion kWh, more than the total power generation of the Three Gorges Power Station in 34 years. Therefore, various regions have introduced building energy efficiency policies, and building energy efficiency regulations have been gradually improved, from 50 energy saving and 65 energy saving to 75 energy saving and passive building changes. When satisfied with increasingly higher building energy efficiency codes, the contrast between traditional building insulation materials in terms of fire protection and insulation has become more prominent. The aerogel thermal insulation products together have the advantages of Class A fire protection and excellent thermal insulation functions, opening up a new horizon for building energy saving and thermal insulation.
In the field of industrial pipe network, following the development of urban underground induction pipe corridors and the compact structure design of industrial fields such as power plants and chemical plants, the thermal insulation of industrial heat pipes not only puts forward higher energy-saving requirements, but also takes up space. Propose certain constraints. Aerogel products have low thermal conductivity, small package thickness, and good energy-saving effect. Taking the thermal insulation application of 350℃ steam pipeline as an example, compared with traditional thermal insulation materials, the thermal insulation thickness of aerogel is reduced by 2/3, energy consumption is saved by more than 40%, and carbon dioxide emissions per kilometer of pipeline can be reduced by 125 tons per year.
Do you know the hardness of nano aerogels
As we all know, nano-aerogel is the smallest density solid known in the world. Generally, more than 80% of aerogel is air, so it looks very "weak". Judging people by their appearance", aerogels are "little guys" who can accept temperatures of 1400 degrees Celsius, so some people want to know how hard the aerogel is.
Aerogel looks like "skinny", but it's actually very strong. It can accept a pressure several thousand times its own mass, and will only melt when the temperature reaches 1200 degrees Celsius. In addition, its thermal conductivity and refractive index are also very low, and the insulation can be 39 times stronger than a relatively good glass fiber.
The aerogel has a large hardness, and it looks "beautiful", has a remarkable fire protection effect, and has superior performance. It is really "not a person to look like", just like an ant, it looks small, but it has strength. Able to bear the pressure equivalent to 1700 times its own body weight.
Why can aerogel, a material lighter than air, protect it from wind and rain?
Speaking of the history of the invention of aerogel, it must be said that it was an accident. To be precise, it was invented by the American Kistler inspired by jelly in 1931. Everyone is definitely not unfamiliar with jelly, but it is estimated that few people will think about a question: Hey, since the ingredients of jelly are all water, how can the water in it not flow out? In fact, jelly is a kind of hydrogel. The so-called gel refers to a semi-solid substance rich in liquid after the sol loses its fluidity. Its principle is as follows: The water molecules in the jelly grid are pulled by surface tension, and the size of this surface tension is just enough to make the water unable to break free and sway, so that the final finished jelly will be obtained. What happens if the liquid inside is pumped out and replaced with gas? According to this idea, the American Kistler finally chose silica gel as the test object after countless experiments, and used the supercritical drying method to remove the liquid components in the silica gel. The brilliance of this experiment is that he first replaces the water with alcohol, then converts the alcohol into gas in a supercritical state, and then slowly releases the alcohol gas. At this time, because there is no capillary force caused by the liquid, the mesh can maintain the original structure. Thus successfully made the world's first real aerogel-silica aerogel. I have to say that this method is really clever!
China's aerogel development
Let's take a look at China's achievements. Research on aerogels in my country started late, but the speed of development is very fast, and a series of important results have been achieved, some of which are even in the forefront of the world. For example, in 2013, researchers from Zhejiang University used carbon nanotubes and graphene to prepare an ultra-light aerogel named "carbon sponge", which is currently the world's lightest material. In a vacuum, 1 cubic centimeter of carbon sponge weighs only 0.16 mg. The weight of the same volume of ordinary air is about 7 times that of it, which is lighter than the same volume of helium. In addition to being light, its absorption capacity is also very strong! Existing oil-absorbing products generally can only absorb liquids about 10 times their own mass, while the absorption capacity of "carbon sponges" is about 250 times, up to 900 times. At the same time, "Carbon Sponge" has high elasticity and can be restored to its original shape after being compressed by 80%.
Uses of aerogels
After talking for a long time, what's the use of aerogel? In summary, aerogel has three advantages: light weight, strong heat insulation, and high endurance. First of all, its density is about one-thousandth of that of glass. It is no exaggeration to say that it is the world's lightest material. Secondly, aerogel can block almost all the ways of heat transfer, so as to achieve the insulation effect that other materials can't match, and finally it can withstand a pressure that is thousands of times its own mass. Maybe you would say, this is nothing, I still understand the truth of "the pillar is strong!" But if you understand the nature of aerogel, you will be surprised at its magic! It is precisely because of so many advantages that aerogels are widely used in all walks of life. For example, in the fields of aerospace and national defense, aerogel can be used as an insulation material for aircraft cabins, as well as for nuclear reactors in nuclear submarines and steam-powered guided missile destroyers, as well as high-efficiency insulation materials for complex high-temperature steam boiler systems. This time, China’s "Tianwen-1" Mars rover and "Zhurong" Mars rover use aerogel materials, and two different materials are used to combat the temperature of the Martian "Ice and Fire" test. For example, high-temperature-resistant nano-aerogel thermal insulation components are used to block the high-temperature heat flow up to 1200°C generated by the landing engine and protect the normal function of the landing platform. The low-temperature resistant nano-aerogel components are used on the surface of the "Zhurong" rover, which can ensure that the rover can work normally at -130°C. At the same time, "Zhurong" also uses a variety of new materials such as aluminum honeycomb sandwich, aluminum-based silicon carbide, composite fiber, etc., which can improve the high wear resistance and stability of the rover. And its basic parts and components have achieved localization, and the localization rate of components has exceeded 90%.
Silica nanofiber aerogel for salt-tolerant solar seawater desalination
Billions of people around the world still do not have access to sufficient and clean fresh water. Desalination of solar energy from salt water is considered to be one of the most promising proposals to solve this serious crisis. However, most of the reported evaporators so far still have the problem that the evaporation rate decreases due to the accumulation of salt crystals on the surface. Recently, the research team of researcher Bin Ding of Donghua University and Professor Hongbing Deng of Wuhan University was inspired by the vascular tissue structure, transpiration and antifouling function of reed leaves. The team designed biomimetic layered nanofibers with parallel arranged blood vessels and hydrophobic surfaces. Aerogels are used for high-efficiency and salt-tolerant solar seawater desalination.
The foldable blood vessel walls and soft silica nanofibers give nanofiber aerogels (R-NFAs) inspired by reed leaves excellent mechanical properties and enable them to withstand repeated compressions. In addition, R-NFAs can effectively absorb sunlight (light absorption efficiency: 94.8%) and evaporate salt water into steam, similar to reed leaves (evaporation rate: 1.25 kg m–2 h–1 under 1 sun). More importantly, through the hydrophobic surface and the parallel arrangement of the containers, R-NFAs can work stably in high-concentration salt water (saturated, 26.3 wt%) under high-intensity light (up to 6 sunlight), showing strong resistance Salty.
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