The purpose of surface modification of ultrafine powder is: 1. In order to improve or change the dispersibility of powder particles; 2. Improve durability, such as resistance, light resistance, heat resistance, weather resistance, etc.; 3. Improve particle surface activity; Adding new physical, chemical and mechanical properties and new functions to the surface of the particles to increase the added value of the powder.
At present, there are many methods for surface modification, and the classification method varies depending on the angle of analysis of the problem. The powder surface modification methods are divided into six categories, namely: surface coating modification, surface chemical modification, mechanical force chemical modification, capsule modification, high energy modification, and precipitation reaction modification.
Let us introduce the principle and function of Mechanical chemical modification. Mechanical chemical modification refers to the change of mineral lattice structure, crystal form, etc. by mechanical methods such as pulverization, grinding, friction, etc. The internal energy of the system increases, the temperature rises, and the particles are dissolved, thermally decomposed, and free. A modification method in which the surface or the ion enhances the surface activity of the mineral and causes the mineral and other substances to react or adhere to each other to achieve the purpose of surface modification.
Wang Dongzhi et al. studied the surface modification process of heavy calcium in agitating mills. The results show that the mechanochemical action in the medium agitating mill plays a positive role in the modification of heavy calcium, and the particle size of heavy calcium is reduced and the specific surface area is increased. . Under this action, AA, AS (two modifiers, domestically produced) agents are chemically adsorbed on the surface of heavy calcium, achieving simultaneous grinding and modification, which plays a role of dispersion and grinding. Xu Xiangyang et al used mechanochemical treatment to modify the surface of nanodiamond. Using the synergistic effect of mechanical force and surfactant, the surface of nanodiamond, especially the newly formed surface during the pulverization process, was modified to adjust the hydrophilic and hydrophobic properties of the surface. Thereby achieving stable dispersion of nanodiamond in white oil medium. The mechanical chemical reaction modification can combine the pulverization process with the surface modification process, and has the characteristics of simple process, good modification effect and high production efficiency. Ding Hao and Lu Shouci used sodium stearate as a modifier to study the surface modification of wet superfine grinding calcium carbonate particles in agitating mill. The research shows that the mechanical and chemical effects in the wet superfine grinding process are It is beneficial to the surface modification of the particles, and the modification effect is affected by the fineness of the grinding, the concentration of the slurry, the pH, the temperature of the slurry and the grinding force, among which the influence of the grinding force is most important. Gu Huazhi and others grind CaCO3 and Ca(OH)2 with a certain mass ratio in a planetary ball mill to achieve Ca(OH)2 coating and activation of CaCO3, and improve the hydration resistance of CaO formed by CaCO3 decomposition. A refractory material with good performance.
Wang Dongzhi et al. studied the surface modification process of heavy calcium in agitating mills. The results show that the mechanochemical action in the medium agitating mill plays a positive role in the modification of heavy calcium, and the particle size of heavy calcium is reduced and the specific surface area is increased. . Under this action, AA, AS (two modifiers, domestically produced) agents are chemically adsorbed on the surface of heavy calcium, achieving simultaneous grinding and modification, which plays a role of dispersion and grinding. Xu Xiangyang et al used mechanochemical treatment to modify the surface of nanodiamond. Using the synergistic effect of mechanical force and surfactant, the surface of nanodiamond, especially the newly formed surface during the pulverization process, was modified to adjust the hydrophilic and hydrophobic properties of the surface. Thereby achieving stable dispersion of nanodiamond in white oil medium. The mechanical chemical reaction modification can combine the pulverization process with the surface modification process, and has the characteristics of simple process, good modification effect and high production efficiency. Ding Hao and Lu Shouci used sodium stearate as a modifier to study the surface modification of wet superfine grinding calcium carbonate particles in agitating mill. The research shows that the mechanical and chemical effects in the wet superfine grinding process are It is beneficial to the surface modification of the particles, and the modification effect is affected by the fineness of the grinding, the concentration of the slurry, the pH, the temperature of the slurry and the grinding force, among which the influence of the grinding force is most important. Gu Huazhi and others grind CaCO3 and Ca(OH)2 with a certain mass ratio in a planetary ball mill to achieve Ca(OH)2 coating and activation of CaCO3, and improve the hydration resistance of CaO formed by CaCO3 decomposition. A refractory material with good performance.
The article from : https://www.satnanomaterial.com/
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