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Chemical modification and dispersion is to use the surface groups of nanoparticles to form chemical bonds with reactive organic compounds. The nanoparticles are soluble in organic media due to the branched chains or groups of organic compounds on the surface. dispersion in. There are usually two ways of chemical modification: one is to use the end groups of macromolecules to chemically react with ...
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Nanoparticles have a special surface structure, which lacks adjacent coordinating atoms on the surface, and has high activity, so it is easy to agglomerate. Due to the strong self-absorption property among nanomaterial particles, the agglomeration of nanoparticles is inevitable. Aggregates can be divided into two types: hard agglomerates and soft agglomerates. The formation process of agglomerates...
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Nanomaterials exhibit many exotic properties that traditional materials do not have. The first thing we need to know is that the nanometer (mainly refers to less than 100nm) of the composition of nanomaterials has four major effects: 1. Small size effect The boundary conditions of the crystal periodicity are destroyed; the atomic density near the surface layer of the amorphous nanoparticle decreas...
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The specific surface area is the surface area (㎡/g) of the substance per unit mass. It is one of the most important physical properties of ultra-fine powder materials, especially nano-powder materials. It is used to evaluate their activity, adsorption, catalysis and other properties. important physical properties. Therefore, in the research, manufacture and application of various ultrafine powder ...
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Fisher's method is a relatively simple particle size measurement method, which is based on measuring the speed of air passing through the powder accumulation, and then obtaining the average particle size of the powder according to the Kozeny-Carman formula. However, the Fisher method is a relative measurement method, which cannot accurately determine the true particle size of the powder, and is on...
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Transmission Electron Microscope (TEM) Transmission electron microscopy uses an electron beam that penetrates a sample to image, which requires the sample being observed to be "transparent" to the incident electron beam. Transmission electron microscopy is widely used in materials science and biology. Since electrons are easily scattered or absorbed by objects, the penetration is low, and the dens...
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This is a method of synthesizing boron nitride by reacting borax and ammonium chloride as the main raw materials in an ammonia atmosphere. The two raw materials should be dehydrated and recrystallized separately before participating in the reaction. Borax is best dehydrated in a vacuum at 200~400°C. The recrystallization of ammonium chloride is to dissolve it into a saturated solution, filter to r...
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The synthesis of boron nitride by nitridation with boron anhydride (B4O3) is one of the important methods for industrial production of boron nitride. Due to the low melting point of boron anhydride (glass state is 294°C, crystalline state is 450-600°C), it becomes a high-viscosity melt at the nitriding temperature, which hinders the flow of ammonia and makes the reaction slow and extremely incompl...
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In summer, the sun is strong, and the sunlight enters the room through the glass, causing the temperature in the car to rise sharply, which seriously affects the comfort of living and vehicle riding. Among them, the energy in the infrared band accounts for the largest proportion, and it is also the main source of energy for the temperature increase in the place where the sunlight is irradiated. By...
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Glass thermal insulation coating is a kind of coating prepared by one or more nano powder materials. The nano materials used have special optical properties, that is, they have high blocking rate in the infrared region and ultraviolet region. , has a high transmittance in the visible region. Using the transparent and heat-insulating properties of the material, it is mixed with an environmentally f...
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In the world of electronic materials there are two important material properties "electrical conductivity" and "thermal conductivity". Generally speaking, as long as the electrical conductivity of the material is good enough, the thermal conductivity is also good. For example, copper, silver, aluminum and other metal materials have good electrical and thermal conductivity. Therefore, most metal ma...
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In the process of powder storage, transportation and use, it is often hoped that the nano-aluminum powder exhibits low activity and is less affected by external environmental factors (temperature, humidity, etc.), so that the product has stable performance for a long time. On the other hand, it is desirable to exhibit high activity in solid rocket propellants to obtain high energy release rate and...
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