Explanation

nanosized powder refers to the particle size less than 100 nm, which is usually observed with a high-resolution electron microscope. The preparation of nanosized powder mainly involves two methods: gas phase method and liquid phase method. The vapor method includes chemical vapor deposition (CVD, chemical vapor deposition), laser vapor deposition (LCVD, laser chemical vapor deposition), vacuum evaporation, electron beam sputtering and ray beam sputtering. In terms of liquid phase method, it covers sol-gel method, hydrothermal synthesis method and precipitation method. Among them, the sol-gel method is widely used in the preparation of nano powder. nanosized powder has unique functions, which is mainly due to the combined effect of surface effect and volume effect. Because most atoms are located on the surface of nanoparticle, each particle has a very high surface energy. On the other hand, volume effect refers to the change in the properties of a substance when the particle size decreases to a certain extent. For example, metal particles with several nanometers in size may lose their typical metal properties, such as superconductivity and magnetism, at extremely low temperatures. Ultrafine nano powder has been widely used in many fields, such as printing large electronic computer integrated circuits with slurry, preparing high-efficiency purification microporous filters, manufacturing high density audio tapes, video tapes, magnetic liquids and high-efficiency catalysts. These applications make full use of the special properties of nanoparticle, thus realizing various functional requirements.

Classification