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The Seven Methods for Preparing Spherical Alumina

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Update time : 2022-01-18 16:57:43
Spherical alumina is a spherical alumina produced by high temperature melt injection, high spherical rate, high alpha phase aluminum oxide content, showing superior performance when rubber, plastic filler, and ceramic feedstock.
Trunnano has made some simple summary of the method of preparing spherical alumina, each of which has its own characteristics: the homogeneous precipitation method is more mild, but in order to obtain spherical powder, aluminum sulfate is usually necessary, so in calcination In the stage, harmful sulfides; in the sol-emulsion-gel method, in order to form emulsion, a large amount of organic solvent and surfactant, the separation process of spherical powder in the emulsion is very cumbersome, and The drying and calcination stage is not easy to maintain the spherical shape; the droplet method is suitable for the preparation of spherical alumina having a large particle size and uniform size, but the use of hot oil and a long time to keep the sol for the shortcomings of the droplet method; due to the template Performance determines the final appearance of the powder, so it is necessary to use a strict requirements in the template method; the aerosol decomposition method and the injection method apply to the production of microscopic to nano-grade alumina powder, although the reaction equipment is complex, but easy to achieve industrialization.
The seven methods for preparing spherical alumina are as follows:
1.Various sedimentation method
The precipitation process in the homogeneous solution is a crystal nucleation, and then the aggregation is greater, and finally from the solution from the solution, it is usually unbalanced state, but if the concentration of the precipitant is lowered in the homogeneous solution, even slowly Generation, then a large number of microcrystal nuclei will be evenly generated, and finally formed finely precipitated particles are uniformly dispersed in the entire solution, and a balanced state is maintained in a relatively long period of time. Method for average prediction method. With Al2 (SO4) 3, Al (NO3) 3 and urea as the raw material, under the conditions of the oil bath 98 ° C, the hydroxide generated by the slow hydrolysis of urea is a precipitant, and the spherical hydroxide precursor is obtained, and By adjusting the ratio of SO42- with NO3-, the size of the precursor particles is adjusted, and the spherical morphology can still be maintained after calcination. Alumina solution was prepared using Al2 (SO4) 3, and the obtained colloid particles also have a very good spherical morphology. This method was used in Al2 (SO4) 3 and urea as raw materials, and the spherical and hollow spherical alumina powder was prepared under different conditions, and for a homogeneous precipitation method, if the obtained precipitated particles were in the range of colloid particles, Then this method is also called a sol gel method. In addition to the conditions of SO42 - present, it is often difficult to finally form a glue of the globiosis in the gelation of sol particles to finally form a globiotype, so people think that this formation of sol-emulsion-condensation Gladle.
2. Sol-emulsion-gel method
This method is developed based on the sol gel method, in order to obtain spherical powder particles, people use the interface tension of the oil phase and the aqueous phase to make small spherical droplets, so that the formation of sol particles and gelation It is defined in tiny droplets, and finally obtains the spherical precipitation particles. Using aluminum hydrolysis, the spheroidized alumina powder was prepared by the sol gel process, wherein the octanol of dissolved aluminum accounted for 50%, the acetonitrile solvent accounted for 40%, and the octanol and butanol of dispersed water accounted for 9% and 1% respectively. Using hydroxypropylcellulose as a dispersant to obtain a spherical γ-alumina powder having a very good spherical degree.
3. Drip method
The droplet method is to bind the alumina sol into the oil layer (usually using paraffin, mineral oil, etc.) to form a spherical sol particulate, and then the sol page is gelled in an aqueous ammonia solution, and finally gel particles Methods of drying, calcining forming spherical alumina. This method is to further improve the sol - emulsion-gel method in the process, and the emulsion technology is applied to the aging stage of the sol, and the oil phase is maintained, and the separation treatment of the powder and the oily agent is omitted.
4. Template method
The template method is a reagent that controls the morphology in the process of spherical feedstock, and the product is usually hollow or a nuclear shell structure. The commercial micron spherical aluminum powder is a raw material, and the aluminum powder surface is used to simplify the surface of the aluminum powder. The template method is a good method for preparing an air spherical sphere, but is higher in the template agent, and the preparation process step is more, it is not easy to operate.
5. Gas solve decomposition method
The aerosol decomposition is usually based on an aluminum salt as a raw material, which utilizes the properties of aluminum alcohol salts and high-temperature pyrolysis, and uses a physical means of phase transition to gasify alkoxide, and then contact with water vapor, and then The high temperature dry or direct high temperature is picked, thereby achieving a transition of gas-liquid-solid or gas-solid phase, and finally forming a spherical alumina powder. Complex experimental devices consisting of atomizing moiety and reaction moieties are the key to this method. 
6. Radio frequency induction plasma method
Radio frequency plasma spheroidization treatment of alumina powder, using radio frequency plasma having high energy density, high heating strength, large amount of mass torch, and the simple processing material process, etc. However, without electrodes, it is not contaminated due to electrode evaporation. It is possible to ensure the purity of alumina; in addition, the shape irregular alumina particles are sprayed into the plasma torch by the feed gas, and the melting of the plasma is rapidly heated. Droplets and quickly solidify in a very short period of time, thereby forming spherical particles.
7. Jet
The essence of spinal alumina is made in a short period of time, and the product is spherically formed by the action of surface tension. According to the characteristics of phase transition, it can be divided into spray heat solution, spray drying and spray melting Law. AlCl3, Al2 (SO4) 3, Al (NO3) 3 solution form spherical droplets by atomization, and gently generated spherical powder through high temperature heat, this process requires a thermal decomposition temperature of 900 ° C, which is large. The author first reacts the aluminum salt solution to the ammonia to form an alumina sol, and then spray the alumina sol at 150-240 ° C, or the spherical product can also be obtained.
Luoyang Trunnano Tech Co., Ltd (TRUNNANO) is a professional Spherical alumina supplier with over 12 years experience in chemical products research and development. We accept payment via Credit Card, T/T, West Union and Paypal. Trunnano will ship the goods to customers overseas through FedEx, DHL, by air, or by sea.
 
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