The features of the nanophase materials
Broadly speaking, nanomaterials refer to materials that have at least one dimension in the three-dimensional space in the nanoscale range (1 ~ 100mm) or composed of them as basic units.
characteristic:
(1) Surface and interface effect This refers to the change in properties caused by the ratio of the number of atoms on the surface of the nanocrystal particles to the total number of atoms as the particle size becomes smaller and sharply increases. For example, when the particle diameter is 10 nm, the particles contain 4000 atoms, and the surface atoms account for 40%; when the particle diameter is 1 nm, the particles contain 30 atoms, and the surface atoms account for 99%. The main reason is that the diameter decreases and the number of atoms on the surface increases. For another example, when the particle diameter is 10 nanometers and 5 nanometers, the specific surface area is 90 square meters / g and 180 square meters / g, respectively (measured using a fully automated F-Sorb 2400 specific surface area meter BET method). Such a high specific surface area will show some very strange phenomena, such as metal nanoparticles will burn in the air, inorganic nanoparticles will adsorb gas and so on. The research on the specific surface area of ​​nanomaterials is very important. The detection data of specific surface area of ​​nanomaterials is only reliable when the results are detected by BET method. There are many instruments in China that can only be tested by direct comparison method. Now it has been eliminated in China. . At present, the multi-point BET method is used uniformly for the specific surface area testing at home and abroad. The specific surface area measurement standards developed at home and abroad are based on the BET test method. Please refer to China's national standard (GB / T 19587-2004)-Gas adsorption BET principle Method for determining the specific surface area of ​​solid materials. The measurement of specific surface area is actually a time-consuming task. Due to the different adsorption capacity of the sample, the test of some samples may take a whole day. If the test process is not fully automated, then the tester ca n’t leave at all times. A high degree of concentration, observing the instrument panel, manipulating the knob, and a little inattention will lead to the failure of the test process, which will waste a lot of precious time of the tester. Among several domestic manufacturers of specific surface area analyzers, only the F-Sorb 2400 specific surface area analyzer of Beijing Jinyi Spectrum Technology Co., Ltd. is an instrument that can truly realize the detection function of the BET method (both with direct comparison method), and the more important Beijing Gold F-Sorb 2400 specific surface area analyzer is the only fully automated and intelligent specific surface area detection equipment in China. Its test results are highly consistent with international standards, and its stability is also very good. At the same time, it reduces human errors. Improve the accuracy of test results.
(2) Small size effect When the size of the nanoparticle is equal to or smaller than the physical wavelength such as the wavelength of the light wave, the De Broglie wavelength of the conducting electron, the coherence length of the superconducting state, and the transmission depth, its periodic boundary is destroyed Make its sound, light, electricity, magnetism, thermodynamics and other properties show "novel" phenomenon. For example, copper particles become non-conductive when they reach the nanometer size; insulated silica particles start to conduct electricity at 20 nanometers. For another example, a tool made of a polymer material and a nano material is harder than a diamond product. Using these characteristics, solar energy can be efficiently converted into thermal energy and electrical energy, and in addition, it may be applied to infrared sensitive elements, infrared stealth technology, and so on.
(3) Quantum size effect When the size of the particle reaches the nanometer level, the electron energy level near the Fermi level is split into a standing energy level from a continuous state. When the energy level gap is greater than the thermal energy, magnetic energy, electrostatic energy, magnetostatic energy, photon energy or supercondensation energy of the superconducting state, the quantum effect of nanomaterials will appear, thereby making it magnetic, optical, acoustic, thermal, electrical, superconducting Variety. For example, there is a kind of metal nanoparticles that has a very strong ability to absorb light. As long as one thousandth of these particles are placed in 1.1365 kg of water, the water will become completely opaque.
(4) Macro quantum tunnel effect The ability of micro particles to penetrate the barrier is called the tunnel effect. The magnetization of nanoparticles also has a tunneling effect. They can change through the potential barrier of the macroscopic system. This kind of macroscopic quantum tunneling effect is called nanoparticles.
Outdoor bench refers to the seating facilities used in outdoor places, often commonly found in parks, squares, leisure areas, scenic spots and other outdoor environments. The classification of outdoor benches can be introduced according to many aspects such as material, shape and function.
First, classification by material
1. Wooden bench: Wooden bench is one of the most common outdoor benches, usually made of natural wood, with natural and environmentally friendly characteristics. Wooden benches are usually made of solid wood or artificial wood, and the surface is treated with waterproof and anti-corrosion, which can adapt to various climatic conditions in the outdoor environment.
2. Metal bench: Metal bench is made of metal materials, such as cast iron, steel, etc. The metal bench is durable, corrosion resistant, easy to clean and is suitable for all kinds of outdoor environments.
3. Stone bench: Stone bench is made of marble, granite and other stone, which has the characteristics of good texture and beautiful appearance. Stone benches are generally suitable for high-end places such as garden scenic spots and can be integrated with the surrounding environment.
5. Combined material bench: Combined material bench refers to the bench made of different materials, such as the combination of wood and metal, stone and plastic combination. Combined material bench can usually combine the advantages of different materials, more in line with the needs of different outdoor environments.
2. Classification by shape
1. Linear bench: Linear bench is the most common shape of bench, generally composed of a row of seats, forming a straight line arrangement. The linear bench is suitable for outdoor places with large pedestrian flow and can provide more seats.
2. Arc bench: Arc bench is an arc bench composed of multiple seats, usually used in a ring seat area or landscape area. The curved bench can not only provide comfortable seating, but also increase the aesthetics of the place.
3. Wavy bench: The wavy bench is a bench composed of multiple seats in the shape of undulating waves, giving people a sense of movement and flow. The wavy bench is suitable for parks, squares and other places that need to increase vitality and fun.
4. Round bench: A round bench is a round bench composed of a number of seats, which is usually used in outdoor recreation areas and can provide a place for groups to gather.
3. Classification by function
1. Leisure bench: Leisure bench is a common form of outdoor bench, it can provide comfortable seats, so that people can relax in the outdoor environment.
2. Viewing bench: Viewing bench is usually set in a scenic outdoor environment, providing comfortable seats for people to enjoy the scenery.
3. Sitting bench: Sitting bench is usually set in parks, squares and other places with large traffic, to provide people with a short rest and relaxation.
4. Cool pavilion bench: Pavilion bench refers to a form of combination of bench and pavilion, which can provide sunshade, rain prevention and other functions, suitable for outdoor leisure areas.
In short, the classification of outdoor benches can be divided from many aspects such as material, shape and function. Different outdoor environments and needs need to choose a suitable bench type to provide comfortable and beautiful seating facilities
Beach Bench,Deck Chair,Deck Bench,Waterproof Bench
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