Ultra-fine powder material surface modification method of generalization-Iota

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Service > Ultra-fine powder material surface modification method of generalization

Ultra-fine powder material surface modification method of generalization

Superfine Powder surface modification purposes: 1, in order to improve or alter dispersible powder particles; 2, to improve durability, such as resistance, light resistance, heat resistance, weather resistance; 3, to improve the surface of the active particles; 4 , the surface of the particles to generate new physical, chemical and mechanical properties as well as new features to increase the added value powder.
At present, the surface-modified in many ways, depending on the perspective of classification issues vary. Powder surface modification methods are divided into six categories, namely: Surface coating, surface chemical modification, mechanical strength - chemical, capsule-modified, high-energy modification, precipitation modification. China Powder network editor for more than six kinds of modification of the comb as follows.
I. Surface coating
Surface coating surface modifier is no chemical reaction with the surface of the particles, the method relies on physical or van der Waals forces between the cladding and particle connection, the method is suitable for almost all types of surface modified inorganic particles. This method is mainly used for inorganic or organic compound coated particles, reduced agglomeration of particles, and because garments to produce the steric repulsion, the particles agglomerate again very difficult. Modifiers for coating modification of a surfactant, hyperdispersants, minerals and the like.
Zhao Haiyan and other tartaric acid as a surfactant, study of SiC slurry flow properties. The results showed that: the amount of tartaric acid have very different degrees of impact on the silicon carbide powder surfactant. Under normal circumstances, tartaric acid in an amount of 0.05%, the silicon carbide surface modification effect of the best.胡圣飞 and other polyester hyperdispersant Modified Nano and paste viscosity plasticizer used to characterize nano-calcium carbonate filler in a resin flow and dispersion of good or bad, the viscosity modification effect of the smaller the better , the paste viscosity modified nano calcium carbonate significantly reduced.陈飞跃 and other ultra-dispersant carbon black is modified, the results show hyperdispersant added significantly improves the dispersion properties of the system at optimum dispersant content, the system has a high fluidity, low viscosity, little thixotropy and other properties. Yue Linhai coated calcium carbonate and other inorganic silicon dioxide layer, allows it to some extent with a silica properties, surface smoothness, whiteness, acid resistance, dispersion, and so have a greater surface area improve, can greatly improve application performance calcium carbonate. Prabhakaran and other studies of surface modified SiC coated aluminum hydroxide powder. When the coverage of aluminum 0.1mg / m2, SiC powders exhibit similar dispersion properties of alumina, zeta potential of significantly improved; when the aluminum clad layer increases to a certain value, the rheological properties of the suspension is reduced. Polyethyleneimine (PEI) surface modification can improve the flow properties of SiC powder, modified uniform particle size, more spherical shape. Adjusting the pH, changing the binding mode polyethyleneimine and SiC particle surface, polyethyleneimine adsorbed onto the surface of SiC particles increases the electrostatic repulsion between the particles can help improve dispersion and fluidity SiC particle surface. The use of polyethylene glycol as a dispersing agent for industrial surface modification treatment with SiC powder by TG, IR, electron microscopy and other tests studied SiC powder flow characteristics before and after modification, adsorption, TG and morphology properties , the influence of the addition amount of polyethylene glycol and liquid medium for various physical properties. The results showed that: polyethylene glycol adding 5% (by mass), the medium is ethanol, modified SiC powder flow properties is good; the modified better dispersion between particle size distribution, shape, mostly massive distribution, and after the powder sintering properties of silicon carbide ceramics modification has also been improved.
Second, the surface chemical modification
Surface chemical modification by the surface modifying agent chemically react with the particle surface or chemically adsorbed manner. Shirai such as the use of inorganic particle surface hydroxyl groups, has the role of initiating polymerization of groups on the surface of the graft Si, TiO2 ultrafine particles such as carbon black and white, then the vinyl polymer powder surface occurs with these radical initiator reaction, effectively improve the ultra-fine powder in an organic medium dispersion. Li Wei, etc. In the study of carbon black particles surface grafting of acrylic acid was found, under certain conditions, the acrylic monomers can be directly grafted carbon black particles surface, from transmission electron microscope found that due to graft up polyacrylic acid containing long chain ionic hydrophilic group, in an aqueous medium can better stretch steric barrier, preventing re-aggregation of carbon black particles, carbon black particles so dispersed, increasing dispersion stability.
Masaharu Yamatoto a macromolecular synthetic grafting a silane coupling agent and titanium oxide surface, so that the titanium well dispersed in an organic solvent. Boven, etc. and Tsubokawa, respectively, the introduction of the silica surface azo group and peroxide groups initiated graft polymerization of methyl methacrylate. Zhang Wen-gong and other self-made aluminum coupling agent for surface modification of calcium carbonate powder, calcium carbonate modified after moisture absorption, lower oil absorption, particle size becomes smaller, easily dispersed in an organic medium, heat-stable temperature greater than 300 ℃. Jesion.owski, respectively, using mercaptosilanes, vinyl silane and amino silane coupling agent for silica surface treatment. Test results show that after the first two treatment hydrophobic particles increases, the surface a significant reduction in the number of hydroxyl groups, resulting in reduction of secondary aggregates; and amino silane coupling agent had no such effect, mainly because the latter molecule structure In addition to the hydroxy amino react with SiO2 surface, also formed aggregates intermolecular hydrogen bonds which in turn causes the particles.
Third, the mechano-chemical modification
Mechano-chemical modification means that by crushing, grinding, friction and other mechanical methods to make the mineral lattice structure, crystal and other changes in the system can be increased, temperature rise, prompting the particles dissolve, thermally decomposed to produce free group or ions, enhanced mineral surface activity, prompting minerals and other substances react or adhere to each other, to achieve the purpose of the modification method of surface modification.
Wang Dong and other studies known TSP surface modification process in a media agitating mill. The results indicate that a medium stirring mill to play an active role GCC modified mechanical chemical action, and makes TSP particle size reduction, the surface area increase . In this role, AA, AS (two modifiers, domestic production) agents are chemically adsorbed on the surface of the GCC to achieve the abrasive and modified at the same time, play the role of dispersion and grinding aid. Xu Xiangyang and other mechanical chemical treatment of nano diamond surface modification, exploit synergies mechanical force and surfactants, nano diamond surface grinding process, especially the new generation of surface modified, hydrophilic adjust the particle surface hydrophobic properties, in order to achieve stable nanocrystalline diamond dispersion in white oil medium. Mechanical modified chemical reaction process may be crushed and surface modification process combined with a simple process, good modified effects and production efficiency. Ding Hao, 卢寿慈 sodium stearate as modifier, study of wet ground calcium carbonate ultrafine particles while stirring mill surface modification, research shows that the wet ultrafine grinding process of mechano-chemical effect there conducive to surface modified particles, and modifying effect affected fineness of grind, slurry concentration, pH, temperature and the slurry grinding force, of which the most important impact grinding force. Gu Huazhi and so will certain mass ratio of CaCO3 and Ca (OH) 2 is ground in a planetary ball mill, the realization of Ca (OH) 2 对 CaCO3 coating and activation, to improve the hydration resistance formed by the decomposition of CaCO3 CaO to obtain good performance refractories.
Fourth, the capsule modified
Modified capsule is covered with a homogeneous and there is a certain thickness of the film surface modification method on the surface of the powder particles. Rong and other polystyrene on Al2O3, SiO2 coated TiO2 composite particles had been encapsulated, effectively improve the light absorption and stability of the substance. Zhu Liqun and other in-situ polymerization method kinds of microcapsules silicone resin and ceramic fibers as core material, polyvinyl alcohol capsule material to the silicone resin and powder mixture as core material for the capsule material polyvinyl alcohol . Microcapsules containing a silicone resin compound having a liquid flow and good thermal stability and other substances into the sol - gel film by microcapsules repair microcracks effect of the liquid and to improve the sol - gel compound the purpose of the film properties.
Fifth, energy modification method
Modified method is the use of high-energy plasma or radiation treatment initiate the polymerization reaction is achieved modification method. Studies have shown that: the low temperature plasma treatment on glass fiber - epoxy composites have a certain impact performance, glass fiber into the plasma generator processing, with the extension of treatment time, the quality of the glass fibers by a 0.28 percent loss to $ 0.82. This is due to the high energy ions in the plasma-induced etching effect caused by the surface of the fiber pairs. Because of the roughness increases, newborn surface area increases, some polar groups to better expose, so the adsorption capacity of the coupling agent is increased. This is bound to improve the fiber and epoxy resin wettability, thereby improving the interfacial adhesion and mechanical properties of composite materials. A powder by plasma surface modification has been applied to the oxidation treatment of carbon black. Study on plasma treatment of polymer to change its surface properties have been many reports, such as polyethylene by helium plasma treatment. Yongdingzhuang with hexamethyldisiloxane as the monomer, the use of high frequency plasma in a low melting phosphate glass fine powder surface-coated ultrafine polymerized silicone polymer film. Changes in the contact angle between the water and the powder tablet characterization of the effect of plasma process parameters on the powder surface energy. The results showed that the modified powder fineness of electronic slurry preparation, viscosity, rheological characteristics are improved significantly. After modification can alter or control the size of the surface energy of ultra-fine powder, which can regulate electronic slurry rheology and printability.
Sixth, precipitation modified
Precipitation reaction method is powder particles to a solution containing a precipitating agent is added, or may be added to initiate the reaction system to generate the precipitant substance, the modified ion precipitation reaction, the deposited particle surface, thus coated particles. Precipitation can be divided into direct precipitation method, homogeneous precipitation method, heterogeneous nucleation, co-precipitation method, hydrolysis method. Liu Zhi et aluminum flakes coated layer ZnS, prepared composite particles Al / ZnS maintained infrared low emissivity Al powder and simultaneously cover its metallic luster, it is conducive to visible light camouflage compatible. Zhang et al calmly titanium hydride surface evenly coated with a layer of SiO2, prepared composite foaming agent, effectively delayed the release of hydrogen time nuclear materials.

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