Application of Nano-powder in Thermal Insulation Materials Wang Chao 12, Zhong Qingdong 1 Meng Xinjing 1 Yuan Li 3, Sun Zhongqu 3, Qi Xi 3 (1. School of Energy and Environmental Engineering, Shanghai University of Electric Power, Shanghai 2 School of Materials Science and Engineering, Shanghai University , Shanghai 200072 3. Shanghai Baosteel Co., Ltd., Shanghai thermal insulation nano-inorganic organic composite materials, thermal insulation nano composite film materials. Fund Project: National Natural Science Foundation of China (5057105950615024) Shanghai Science and Technology Commission Nano Special Project (0452nm042); Shanghai Education Commission Key Project (05ZZ54) Shanghai Science and Technology Commission Qixing Project (04QMX1451); Shanghai Key Discipline Construction Project (P1304). The application of nanotechnology has brought new challenges to traditional thermal insulation materials science. Based on this paper, the application of nano powder in thermal insulation materials is further introduced. 1 Insulation Nanomaterials 11 nm xonotlite xonotlite is one of the hydrated calcium silicate minerals. Among all hydrated calcium silicate minerals, xonotlite is the mineral with the lowest crystal water content and the best temperature resistance. The decomposition temperature of the xonotlite is 1 050~1100 ° C. At this temperature, the xonotlite crystal hardly changes, even if the decomposition reaction occurs, the volume change caused by the lost crystal water is not changed. Large, will not cause devastating damage. The xonotlite as the insulating material is hydrothermally synthesized from an SD2 raw material (such as quartz) and a cao material (such as lime) in an autoclave. The xonotlite is generally needle-like or fibrous. Depending on the starting materials and reaction conditions, the fibers may have diameters ranging from a few microns to less than 100 nm. These fibers are intertwined, entangled, and intertwined to form hollow secondary particles having a bird-like structure. Inside the secondary particles, it is not completely hollow, but the sparse xonotlite fibers are interlaced and distributed to divide the interior into smaller spaces. On the outside of the secondary particles, the xonotlite fibers are denser and form a tight, solid outer shell. Some of the fibers are epitaxially grown to form spikes that extend toward the outer shell. Therefore, these xonotlite secondary particles are also referred to as chestnut-shaped secondary particles, and their diameters are generally from ten to several tens of micrometers. The xonotlite type calcium silicate insulation material is formed by closely packing such secondary particles. Generally speaking, the finer the diameter of the xonotlite fiber crystal at the same bulk density, the smaller the internal pore size, and the lower the thermal conductivity, the higher the strength of the product. According to different manufacturers and different products, the maximum use temperature of the xonotlite type calcium silicate insulation material is generally in the range of 9001100 °C. The high temperature resistance is mainly related to the content of xonotlite in the material and the degree of crystallization of the xonotlite. If the content is above 99%, its maximum use temperature can reach 1 2 calcium silicate composite nanoporous super insulation material super insulation material is a thermal insulation material that guides the thermal coefficient to be less than "stationary air". Due to the small pore size to the nanometer scale, the following nano-effects are mainly produced: when the pore size in the lightweight material is less than 50 rm, the air molecules in the pores lose the ability to flow freely, and thus the vacuum is equivalent to “zeroâ€. Convection effect." Since the bulk density of the material is small and the pore size is small, the number of pore walls tends to "infinitely, for each pore wall, it has the function of a heat shield, so that it is produced only when it is transmitted in a solid. Passing along the pore wall constitutes an effect close to the "infinite long path", which reduces the ability of solid heat conduction to near the minimum limit. Lysenko et al. prepared nanoporous silicon insulation insulation material, and the prepared nanoporous silicon material has sufficient Thickness (up to 200m) and mechanical strength. 3 nanometer fiber insulation material Nano-scale microfiber insulation material (FBR) is a new material with stable thermal properties and unique self-degradation function. Using it instead of PUR is a new way for the sustainable development of solar water heater tank insulation materials. Among them, F12 type nano-insulation material has the best thermal insulation performance, and its thermal conductivity (20150 /(mK) increases with the increase of temperature. In addition, after the insulation material is heated at 150 °Q for 100s, the back The wall temperature does not exceed 50 ° Q. There are three main ways of heat transfer: conduction, convection and radiation. The heat transfer mechanism is found in solid phase insulation materials. The thermal conductivity of the material consists of three parts, namely the thermal conduction of solids. The convection of gas in the gap and the radiation between the air. When the material is used at high temperature, the radiation heat transfer is the main factor affecting the thermal conductivity; when used at normal temperature, the radiation heat transfer is converted into a secondary factor. The temperature is not too high and the effect of thermal radiation on the thermal conductivity of the material can be ignored. The heat transfer mechanism of the microbead material indicates that in the fiber type nano heat insulating material, both the solid particles and the fiber are used as the heat insulating filler, and therefore, the heat insulating effect is inevitably the result of the joint action of the two. When heat is transferred from the outside to the composite, both solid particles and fibers are encountered. Since the nano-filler itself has a small thermal conductivity and nanometer-sized ultrafine particles as a filler, the particle size and contact area of ​​the particles that can pass heat are very small, and thus the heat transfer capability is low. Further, the hollow microspheres in the heat insulating material have an ultrafine and dense porous structure, and it is difficult to cause gas flow, so that extremely low thermal conductivity can be maintained. Therefore, when heat encounters solid particles, only a small amount of heat is transmitted through the particles, and most of the heat is bypassed by the particles along the outer wall of the particles. The heat transfer mechanism is due to the low thermal conductivity of the particles and good thermal resistance. The performance makes the heat transfer path in the composite material long and complicated, resulting in a decrease in heat transfer performance. 5 Super Insulation Materials Nano-insulation materials are super-insulating materials that appeared in the late 1990s and are a revolution in thermal insulation materials. It is generally believed that a superinsulation material refers to a thermal insulation material whose thermal conductivity is lower than that of a non-convective air under predetermined conditions of use. To achieve super insulation materials: First, the bulk density of the material should be extremely small while maintaining sufficient mechanical strength; the second is to reduce the convection of air to the limit; the third is to pass near infinity The modification of the interface and materials allows the thermal radiation to reflect, scatter and absorb, thus minimizing. It is generally believed that nanoporous superinsulation materials should have the following characteristics: First, almost all pores in the material should be below 100 nm; second, most of the pores in the material (more than 80%) should be less than 50 nm. The material should have a very low bulk density. At present, the weakness of nano-insulation materials is that the manufacturing process and the cost price are both high. However, with the continuous development of nano-technology, the application surface and usage are increasing and increasing, and the prospect is very considerable. It is expected that within five years, there will be an inestimable level of development in terms of variety development, manufacturing technology, applied research, performance testing, cost reduction, and quality improvement. 2Insulation and thermal insulation nano-inorganic organic composite materials 1 nanometer inorganic organic composite agricultural film material agricultural shed film with the development of agricultural high technology, its demand has soared. At the same time, correspondingly, higher requirements are placed on the performance of agricultural greenhouse film. Nanocomposites attract the attention of many researchers because of their many unexpected synergistic properties. From the viewpoint of the composite material, if the particles are hard and are well bonded to the matrix resin, the rigid particles can exhibit a toughening and reinforcing effect. Therefore, by utilizing the characteristics of the nano inorganic particles, the strength, toughness, puncture resistance, and wind resistance of the film can be improved. Since the inorganic nanomaterial has a small scale and does not hinder the transmission of visible light, the inorganic nanomaterial and the agricultural film substrate are combined to not affect the light transmittance of the agricultural film, and the inorganic nano material has a certain crystal nucleation effect and can promote the polymer. The grain is refined to further improve the light transmittance of the agricultural film. The introduction of inorganic components also provides an entry point for further improvement of the thermal insulation properties of the greenhouse film. Inorganic nano-materials with thermal insulation function can be selected, and the high-specific surface characteristics of inorganic nano-materials can be used to load anti-aging and anti-fog dropping aids on the surface of nano-materials, thereby improving the efficiency of use of these auxiliaries. It can improve the anti-migration problem of these small molecule additives, thereby improving the thermal insulation performance of the agricultural film and prolonging the effective period of anti-fog drops. In addition, since the nano-SO2-x particles can block ultraviolet rays and have strong infrared reflection characteristics, it is advantageous for enhancing the thermal insulation performance of the greenhouse film and preventing ultraviolet rays from harming crops. 2 rigid foam polyurethane nanocomposite rigid foam polyurethane (PUR) is a commonly used insulation material for all-glass vacuum tube solar water heaters and hot-arm vacuum tube water heaters. However, PUR is an environmentally harmful material, and its thermal properties vary with time of use, so that the thermal performance of solar water heaters that need to work outdoors for a long time will be greatly reduced with the increase of use time. The raw material of PUR has two major components: one is black material (B), namely isocyanate component (MDI); the other is white material (A), which is a polyol component. The MDI for producing PUR is a crude MDI white material containing a polyether polyol, a foaming agent, a foam stabilizer, a catalyst, a flame retardant, a color paste, and the like. PUR foaming processes mainly include manual casting, low pressure foaming, high pressure foaming, and the like. 3 Ship insulation and insulation materials Ship insulation and insulation materials have always been an important topic in the shipbuilding industry. Up to now, the insulation materials commonly used in ships are still “three cottons†such as mineral wool, glass wool and rock wool, and there are also various defects and irrational applications. These insulation materials also pose potential hazards to the ship during the thermal insulation process. In recent years, a lot of work has been done on the development of new type of ship insulation and thermal insulation materials at home and abroad. For example, there is a secondary development of polyimide foam material modified by chemical structure of materials, and nanoporous inorganic insulation which is physically modified by aerogel. Insulation material, and toughness phenolic foam ship insulation insulation material which is chemically and physically modified by polymer interpenetrating network, ie IPN method. 191. The main heat of sunlight comes from the infrared region, and the nano-scale semiconductor material absorbs infrared light and Very reflective, such as indium tin oxide (ITO), antimony tin oxide (ATO), aluminum zinc oxide (AZD), etc., which is the main component of most current thermal insulation films. Although foreign research on various thermal insulation films is relatively mature, some methods for preparing thermal insulation films have been found, but the higher cost is an obstacle to its continued development. Wang Wei and other water-based polyurethane resin as a film-forming material, mixed with well-dispersed nano-ATO water slurry to prepare a heat-insulating transparent coating, and obtained good results. 111. Nano-tin oxide antimony heat-insulating transparent coating insulation The effect is mainly achieved by absorption and reflection. With the increase of ATO content in the coating, the effect of coating film insulation is more obvious. When the coating film PVC is 0135, the equilibrium temperature of the bottom plate of the wooden box is about 20 ° C lower than that of the blank glass. Spectral analysis shows that the average transmittance in the visible region is up to 75%, and the average blocking ratio in the near-infrared region is 73%, which can provide better thermal insulation and good film properties. 4 nanometer composite heat insulation coating For large-area windows of buildings and transparent ceilings, car windows, etc., the heat radiation of sunlight will increase the utilization rate of air conditioners and waste energy. The traditional solution is to use metal-coated heat-reflecting glass and various heat-reflecting films to achieve thermal insulation and cooling. However, these products also have some problems, and the opacity and high reflectivity of the visible light region limit its application range. The emergence of nanomaterials provides a new way to solve the problem of transparent insulation. Antimony-doped tin dioxide (ATO) is an n-type semiconductor oxide. It has been proved that nano-ATO film has high infrared shielding effect and good visible light transmittance. Zhang Yongjin et al. selected water-based polyurethane as a film-forming agent, nano-ATO as a filler, and made a nano-transparent heat-insulating coating with good performance. 11. When the PVC was 0. 018, the nano-ATO transparent heat-insulating coating was obtained (30Mm). The visible light transmittance is 86 2%, and the shielding rate of light in the near-infrared region (800~2500nm) is 613%. The addition of a small amount of nano-ATO makes the coating have good thermal insulation performance, and its thermal insulation effect is similar to that of expensive foreign countries. The insulation effect of the product is equivalent. The transparent heat-insulating coating can be widely applied to architectural glass, automobile front windshield, etc., and has a good application prospect. At present, it has developed and produced a series of nano-elastic thermal insulation and environmental protection coating materials, such as latex paint, multi-layer embossing paint, fluorescent latex paint, and real stone paint series. Such as fluorescent latex paint as a green product, with high temperature resistance, corrosion resistance, non-deliquess, stable performance, non-toxic, odorless, no radioactive pollution, etc., can absorb the energy of sunlight during the day, and can emit color fluorescence at night. It can be widely used in beautification, lighting engineering and marking coating layer, and is a functional nano-packaging coating material. Luo Zhenyang and others improved the wear resistance and thermal insulation of waterborne polyurethane resin coatings through the combination of nano-Ai3 and nano-ITO wet paste with self-made waterborne polyurethane. 1121. It was found that nano-At3 can greatly improve the coating of waterborne polyurethane emulsion. Wear resistance, when the resin is added with a mass fraction of 4% nano-Ai3, the best wear resistance can be obtained; when the mass fraction of nano-Al23 is more than 6%, the wear resistance is not obvious. The nano-A13 particles have better dispersibility in the aqueous resin, and the nano-Ai3 is compatible with the polyurethane resin in a layered manner when the resin is cured. The nano ITO modified waterborne polyurethane coating film has high visible light transmittance and good infrared barrier property; the waterborne PU film containing nanometer TO mass fraction of 105% has comparable heat insulation performance compared with the imported heat insulation film, but The light transmittance is more excellent. 3 Insulation and nanocomposite film materials are made of double-layer glass, tinted glass, etc., and the heat insulation effect is not very satisfactory. The low-emission (Lowe) glass developed in recent years has a high transmittance for visible light of 380-780 nm, which can ensure the visibility inside or inside the vehicle, and has a far infrared light of infrared light, especially 6~15Mm. The high reflectivity can solve the problems caused by the aforementioned infrared radiation passing through the glass and provide a comfortable living environment. The use of Low-Glass to assemble doors and windows, furnace doors, refrigerated cabinet doors or curtain walls for high-rise buildings not only reduces the energy consumption of lighting, indoor heating equipment and air conditioning equipment, but also reduces the amount of CO2 emitted during fuel combustion and protects the environment. . It can be widely used in the construction industry, automotive industry and home appliance industry 1151. For many metal films and chemical films, when the thickness of the film reaches nanometer level, the optical properties of the film will be abrupt, such as the TO film in the visible region. Transparent, its transmittance is above 90%, and its reflectance of infrared light is also above 90%. It is transparent in the visible range but highly reflective in the infrared. A membrane with a small infrared emissivity is also known as the Lowe system. At present, the most common method for making transparent insulating glass is to coat or film the surface of the glass, but it is difficult to be widely used due to high production cost. In the production of a heat-insulating film, a high-purity indium tin oxide (ITO) nanocomposite powder is generally used to form an ITO target, and then a film is formed on the substrate. HO powder has excellent photoelectric performance, and the reflectivity in the infrared region is 80%. If ITO powder can be used to make transparent heat insulation coating for glass and other substrates, it will have good market prospect and promotion value. The research and development of nano-TO coatings in the United States and Japan started earlier and is at the forefront of the world. Nanophase of the United States first developed a semiconductor nanomaterial TO with infrared reflection properties and dispersed it in water to make a nanopaste. Chen Feixia, Fu Jindong, etc. used indium tin oxide (ITO) water slurry with good dispersibility in water, and silicone resin film-forming agent. By adding co-solvent and adjusting the pH value of the system, a transparent heat-insulating coating with good performance was prepared. 114. The transparent heat-insulating coating prepared by nano-O with better dispersibility in the water system has good spectral selectivity, and the transmittance in the visible light region is over 80%, and most of the infrared light is effectively blocked. Tests on the thermal insulation effect of the transparent thermal insulation coating show that the coating has obvious heat insulation effect. Under the irradiation of the iodine tungsten lamp, the temperature difference between the transparent insulation glass and the blank glass can reach above 10 °C. In addition, the coating film also has excellent hardness, wear resistance, adhesion, flexibility, water resistance and heat resistance, and can meet the practical use requirements of general occasions. 4 Conclusion In the 21st century, as the most promising high-tech nanotechnology, it has injected new vitality into traditional thermal insulation materials science and put forward more innovative topics. It is believed that nanotechnology will be more widely used in this field. (Finish)
2'' wheel plate caster series , as a professional chinese caster manufacturer ,with rich R&D experience , which enable us to customize according to client's request , Size of top plate , wheel material , type of brake , just let me know what you want , Rich Industrial Caster series , various from rigid wheel caster , Swivel Caster and Brake Caster , full size series make us become one-stop caster services center for you .
2'' Wheel Plate Casters,Twin Wheel Casters,Pp Wheel Caster,Mini Size Plate Caster Zhejiang Lingda Caster Co., Ltd , https://www.ldcaster.com