Ultrafine,silver,powder,introd business, insurance Ultrafine silver powder introduction
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Nano silverparticles due to its special structure can produce small size effect, quantumsize effects, surface effects and macroscopic quantum tunneling, so that havephysical and chemical properties which the traditional materials do not have.Nano silver particles occupy a very important position on surface enhancedRaman Spectroscopy, surface enhanced resonance light scattering spectra,molecular biology, supramolecular systems area, it is one of the importantmaterials for basic research. Nano-Silver powder with high surface activity andcatalytic properties, it is widely used in catalyst and ultra-low temperaturerefrigerator thinner. At the same time, because of its unique physical andchemical properties, it also has been widely applied in immunoassay, sensordevelopment, molecular electronics and so on. In addition, add small amount ofsilver in chemical fiber can improve some performances of chemical fiberproducts, and make it have strong sterilization capabilities. Superfine silver powder based on the form can bedivided into roughly spherical, wool, branches and flake types, aftercomplexing silver nitrate with ammonia, add dispersant, add hydrazine restored,washing, filtering, drying to obtain it. According to the grain size can bedivided into: fine silver powder, average particle size is 10~40um; very finesilver powder, average particle size is 0.5~10µm; superfine silver powder,average particle size is less than 0.5µm, nano silver powder particle size isless than 0.1µm. Superfine silver powder is most widely used material in theelectronics industry, as the conductive phase of conductor paste, powdermetallurgy and other raw materials. Ultrafine silver powder's preparation methodsmainly have gas phase method, liquid chromatography and solid-phase. Gas phasemethod have large invested, low energy consumption, low yield; Superfine silverpowder produced by solid-phase with larger particle size and wide particle sizedistribution range; liquid-phase chemical reduction method is the commonmethods of low cost and small quantities prepare ultra-fine silver powder. The principle of liquid-phase chemical reductionmethod prepared ultrafine silver powder is with reducing agents to deposite silver from its salt orcomplexes aqueous solution or organic systems in powder form. Commonly usedreducing agents have formaldehyde, ascorbic acid, glycerol, organic amines,unsaturated alcohols, sodium citrate, hydrazine and hydrazine compounds,commonly used hydrazine hydrate. In silver ammonia solution, adding a certainamount of nitrate additives, under the effect of hydrazine, adjust the amountof additives, can get different size silver powder. The used nitrate additivescan be 1 or 2 kinds, the added amount determined according to the requirements,silver powder prepared by this method with small particle size, small particlesize distribution and good reproducibility. The process of using hydrazine hydrate method toprepare pure silver powder from massive silver or silver nitrate solution, frommassive silver or silver nitrate solution refined silver powder generally doesnot use chlorine or sodium-containing agents. Massive silver is first dissolvedin dilute nitric acid prepared as pure silver nitrate solution. Pure silvernitrate solution adds ammonia to pH 8-10, slowly added with twice thetheoretical amount of aqueous hydrazine at room temperature and stirring,restore for 30 min, stand outputs fine sponge silver. After filtering, washing,drying, sieving will output qualified silver. ArticleSource:http://www.mhcmp.com
Ultrafine,silver,powder,introd