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Preparation method for high-purity flaky alumina

A technology of flaky alumina and hydrated alumina, applied in the preparation of aluminum hydroxide, alumina/aluminum hydroxide, etc., can solve the problems of harsh reaction conditions, high equipment requirements, uneven doping of molten salt, etc. The particle size is uniform, the uniformity of doping is improved, and the effect of meeting application requirements

Active Publication Date: 2016-02-24
SHENGNUO OPTOELECTRONICS TECH QH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

When using the molten salt method to prepare flaky alumina, the morphology of the powder can be controlled by adjusting parameters such as the amount of seed crystals added, the amount of molten salt, the sintering temperature and time, but the disadvantage of this method is that some molten salts have Toxicity, its volatiles may also corrode or pollute the furnace body, in addition, the molten salt is not uniformly doped
Although the hydrothermal method has the advantages of good particle dispersion and good crystal form, it has disadvantages such as long reaction cycle, harsh reaction conditions, and high requirements for equipment.
From numerous published patent literature reports, the prepared flaky alumina is not high in purity (<99.99%), and some contain harmful metal ions, so it cannot meet the application requirements in the fields of cosmetics, high-grade ceramic coatings, fine ceramics, etc.

Method used

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  • Preparation method for high-purity flaky alumina
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  • Preparation method for high-purity flaky alumina

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035] Dissolve 200g of 5N grade aluminum isopropoxide in 294g of isopropanol under heating in a water bath at 80°C to make an aluminum isopropoxide solution (solution A), and place it in a funnel; mix 53g of deionized water with 236g of isopropanol Evenly, then add 10g of analytically pure ammonium fluoride, stir to make it completely dissolved in isopropanol-water solution, prepare solution B, and place it in a four-necked round-bottomed flask; put the four-necked round-bottomed flask containing solution B Put it into the water bath heater, keep the temperature of the water bath at 80°C, then install the funnel containing solution A on the four-necked round-bottomed flask, and install a reflux condenser and a stirrer on the four-necked round-bottomed flask at the same time; Add solution A to solution B gradually at a dropping speed of 1 min, and start stirring at the same time. Under the action of heating and stirring, the aluminum isopropoxide molecules in solution A and the...

Embodiment 2

[0037] Dissolve 612g of 5N grade aluminum isopropoxide in 1080g of isopropanol to prepare aluminum isopropoxide solution (solution A), mix 216g of deionized water with 900g of isopropanol, and 30.6g of ammonium fluoride to prepare solution B, solution A is installed in a funnel, and solution B is installed in a round bottom flask; solution A is added to solution B at a rate of 12mL / min, and the temperature of the water bath is kept at 85°C. Aluminum propoxide molecules react with water molecules in solution B to produce hydrated alumina, and produce isopropanol at the same time. During the heating reaction, the volatilized isopropanol is condensed and returned to the flask; then, the hydrated alumina solution is Alumina hydrate filter cake is obtained by filtration, and the filtrate is isopropanol, which can be recycled and reused; then, the alumina hydrate filter cake is dried in an oven at 160°C to obtain hydrated alumina powder; finally, the hydrated alumina powder is Calci...

Embodiment 3

[0039] Dissolve 1244g of 5N grade aluminum isopropoxide in 1080g of isopropanol to prepare solution A, mix 162g of deionized water with 900g of isopropanol and 61.2g of ammonium bifluoride to prepare solution B, put solution A in a funnel, and solution B Put it in a round bottom flask; add solution A to solution B at a rate of 18mL / min, keep the temperature of the water bath at 65 ° C, under the action of heating and stirring, the aluminum isopropoxide molecules in solution A and solution B The water molecules in the hydrolyzed reaction generate alumina hydrate, and produce isopropanol at the same time, and the isopropanol volatilized during the heating reaction is condensed and returned to the flask; then, the alumina hydrate is filtered to obtain a filter cake, and the filtrate is isopropanol Alcohol, to be recovered and reused; then, put the hydrated alumina filter cake in a vacuum oven and dry at 150°C to obtain hydrated alumina powder; finally, put the hydrated alumina pow...

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Abstract

The invention discloses a preparation method for high-purity flaky alumina, belonging to the technical field of preparation of special powder. The preparation method comprises the following steps: with high-purity aluminum isopropoxide with a purity of 99.999%, pure water and isopropanol as main raw materials and ammonium bifluoride or ammonium fluoride as a crystal morphology controlling agent, dissolving the high-purity aluminum isopropoxide in isopropanol to prepare a solution A; preparing a solution B from pure water, isopropanol and ammonium bifluoride; then gradually adding the solution A into the solution B drop by drop at a certain addition speed; carrying out a reaction under the conditions of heating and stirring so as to produce hydrated alumina; and then successively carrying out filtering, drying and roasting so as to obtain the high-purity flaky alumina. The high-purity flaky alumina prepared by using the method has crystal grain thickness of no more than 1.0 [mu]m, a radial size of 5 to 20 [mu]m, a smooth surface, a flaky shape, no agglomeration and crystal twinning, and good dispersibility, and can be used in fields like cosmetics, pearlescent pigment, high-grade coatings and fine ceramics.

Description

technical field [0001] The invention belongs to the technical field of special powder preparation, and in particular relates to a preparation method of high-purity flaky alumina. Background technique [0002] As a special alumina and an important powder material, flaky alumina not only has the excellent properties of ordinary alumina, such as high hardness, high melting point, anti-alumina, high temperature resistance, corrosion resistance, high thermal conductivity, and high resistivity, but also It also has special properties such as a special two-dimensional sheet structure, moderate surface activity, good adhesion, ability to reflect light, and significant shielding effect. Flaky alumina has been widely used in various fields such as pigments, cosmetics, automotive paints, refractory materials, and toughened ceramics. [0003] Due to the excellent performance and wide application of flaky alumina, its preparation method has become a research hotspot. The methods for pr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/36C01F7/02
Inventor 范秀丽刘江华刘冠华
Owner SHENGNUO OPTOELECTRONICS TECH QH CO LTD
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