Seven preparation methods of spherical alumina

Aluminium oxide is an inorganic substance with the chemical formula Al2O3. It is a high hardness compound with a melting point of 2054°C and a boiling point of 2980°C. It is an ionized crystal that can be ionized at high temperature and is often used in the manufacture of refractory materials.

Industrial alumina is prepared from bauxite (Al2O3·3H2O) and diaspore. For Al2O3 with high purity requirements, it is generally prepared by chemical methods. There are many isomorphous crystals of Al2O3, more than 10 kinds are known, and there are mainly 3 crystal forms, namely α-Al2O3, β-Al2O3, γ-Al2O3. Among them, the structure is different and the properties are also different, and it is almost completely converted into α-Al2O3 at high temperatures above 1300 °C.

The seven methods for preparing spherical alumina are as follows

1. Various settlement methods

The precipitation process in a homogeneous solution is crystal nucleation, then agglomeration is large, and finally it is separated from the solution, usually in an unbalanced state, but if the concentration of the precipitant in the homogeneous solution is reduced, or even slowly formed, it will be A large number of microcrystalline nuclei are uniformly generated, and the resulting fine precipitated particles are uniformly dispersed in the entire solution and remain in equilibrium for a long time. The method is the mean prediction method. Using Al2(SO4)3, Al(NO3)3 and urea as raw materials, under the condition of 98 ℃ oil bath, the hydroxides generated by the slow hydrolysis of urea are used as precipitants to obtain spherical hydroxide precursors, and by adjusting SO42- With the ratio of NO3-, the size of the precursor particles is adjusted, and the spherical shape can still be maintained after calcination. Alumina solutions were prepared using Al2(SO4)3, and the resulting colloidal particles also had very good spherical morphology. This method uses Al2(SO4)3 and urea as raw materials to prepare spherical and hollow spherical alumina powders under different conditions. For the homogeneous precipitation method, if the obtained precipitated particles are in the range of colloidal particles, then this method also called the sol-gel method. In addition to the condition of SO42-existing, in the gelation process of sol particles, it is often difficult to finally form spherical colloids, and finally spheroids are formed, so it is believed that this kind of formation of sol-emulsion-condensation Gladle.

2. Sol-emulsion-gel method

This method is developed on the basis of the sol-gel method. In order to obtain spherical powder particles, the interfacial tension between the oil phase and the water phase is used to make small spherical droplets form sol particles and gelation is defined as tiny droplets. In the end, spherical precipitated particles are obtained. Using aluminum hydrolysis, the spheroidized alumina powder was prepared by sol-gel method, in which octanol dissolved aluminum accounted for 50%, acetonitrile solvent accounted for 40%, and octanol and butanol dispersed water accounted for 9% and 1%, respectively. Using hydroxypropyl cellulose as a dispersant, spherical γ-alumina powder with very good sphericity is obtained.

3. Drip method

The droplet method is to combine alumina sol into the oil layer (usually using paraffin, mineral oil, etc.) to form spherical sol particles, then gel the sol sheets in an aqueous ammonia solution, and finally form the gel particles by drying and calcining. Spherical alumina. The method further improves the sol-emulsion-gel method in terms of technology, applies the emulsification technology to the aging stage of the sol, maintains the oil phase, and separates the powder and the oil. Omit.

4. Template method

The template method is a reagent to control the morphology in the process of spherical raw materials, and the products are usually hollow or core-shell structures. The commercial micro-spherical aluminum powder is used as the raw material, and the surface of the aluminum powder is used to simplify the surface of the aluminum powder. The template method is a good method for preparing air balloons, but the content of template agent is high, the preparation process steps are many, and it is not easy to operate.

5. Gas decomposition method

Aerosol decomposition usually takes aluminum salt as raw material, utilizes the characteristics of aluminum alkoxide and high-temperature pyrolysis, and uses the physical means of phase change to vaporize the alkoxide, then contact with water vapor, and then dry at high temperature or directly pick at high temperature, thereby The transformation of gas-liquid-solid or gas-solid phase is realized, and finally spherical alumina powder is formed. A complex experimental setup consisting of an atomized part and a reactive part is the key to the method.

6. Radio frequency induction plasma method

RF plasma spheroidizing treatment of alumina powder, the use of RF plasma has the advantages of high energy density, high heating intensity, high quality of the torch, and simple processing materials and processes. . The purity of alumina can be guaranteed; in addition, the irregular-shaped alumina particles are sprayed into the plasma torch by the raw gas, and the melting of the plasma is rapidly heated. droplets and solidify rapidly within a short period of time to form spherical particles.

7. Jet

The essence of Spine Alumina is made in a short time, and the product is spherical under the action of surface tension. According to the characteristics of phase change, it can be divided into spray pyrolysis, spray drying and spray melting. The solutions of AlCl3, Al2(SO4)3, and Al(NO3)3 are atomized to form spherical droplets, and spherical powders are gently generated by high temperature heating. This process requires a thermal decomposition temperature of 900 °C, which is relatively large. The author first reacts the aluminum salt solution with ammonia to form alumina sol, and then sprays the alumina sol at 150-240 ° C, and spherical products can also be obtained.

Overview of spherical alumina powder

Alumina is an inorganic substance with the chemical formula Al2O3. It is a high hardness compound also known as bauxite in mining, ceramics and materials science. It is a water-insoluble white solid, odorless, tasteless, and very hard in nature. Moisture absorption but not deliquescence (not hygroscopic after burning). Alumina is a typical amphoteric oxide (corundum is α-shaped and belongs to the densest hexagonal compound. It is an inert compound, slightly soluble in acids and alkalis, and resistant to corrosion. [1] It is soluble in inorganic acid and alkali solutions, but Almost insoluble in water and non-polar organic solvents; relative density (d204) 4.0; melting point 2050 ℃, boiling point 2980 ℃, ionic crystal ionized at high temperature, commonly used in the manufacture of refractory materials.

Low Abrasiveness: Due to its spherical shape, kneaders, molding machines and molds wear less.

Alumina is used to smelt high-quality bauxite to produce brown corundum, while high-quality aluminates are used to produce powdered and white corundum. Their natural crystal structure makes them hard, fast, and used frequently. As a raw material for bonded abrasives and coated abrasives. Alumina Al2O3 can be recycled multiple times, the number of cycles is related to the material grade and specific process. Most standard sandblasting equipment can be used.

Spherical alumina powder should be stored in a dry, cool and airtight environment and should not be exposed to air. Also, avoid heavy pressure and ship as normal cargo. It is packed in double-layer plastic bags and can be vacuum filled with argon; it can be vacuum filled with argon for protection. Vacuum packing, 100G, 500G or 1KG/bag, 25kg/drum, or according to your requirements.

Spherical alumina powder application

1. Paint: enamel paint, wear-resistant paint, plasma spraying.

2. Ceramics: transparent ceramics, bioceramics, alumina ceramics.

3. Petrochemical products: high-efficiency catalysts, catalyst carriers, and automobile exhaust purification materials.

4. Polishing materials: sub-micron/nano-level abrasive materials, single-crystal silicon wafer polishing, and precision polishing materials.

5. Lighting: long afterglow phosphor raw materials and rare earth tricolor phosphor raw materials, high pressure sodium lamps, LED lamps, etc.

6. Electronic products: integrated circuit substrates, single crystal materials, far-infrared materials.

7. Cosmetics: cosmetic fillers.

8. Inorganic membrane materials.

Spherical alumina powder price

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Spherical alumina powder supplier

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