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Method for preparing alpha-alumina powder

A technology of alumina powder and powder, which is applied in the field of preparation of α-alumina powder, can solve the problems of difficult preparation of large single crystal particles and reduced resintering activity, and achieve complete crystal form, narrow particle size distribution, active effect

Active Publication Date: 2008-06-18
中铝郑州有色金属研究院有限公司
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  • Abstract
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Problems solved by technology

However, due to its fine grains and high activity, it forms soft agglomerates at high temperatures, and such agglomerates cannot be opened by ball milling, which reduces its re-sintering activity, so such powders have greater specific surface area, but it is difficult to make a high-density ceramic body, and this method is difficult to prepare single crystal large particle active α-alumina

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  • Method for preparing alpha-alumina powder

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preparation example Construction

[0016] A preparation method of α-alumina powder, the preparation process is first heating and dissolving high-purity aluminum salt, adding surfactant and surface modifier, then adding modified high-purity activated carbon black, stirring, slowly Cool down and crystallize into a mixture of carbon black and aluminum salt crystals; then the black mixture is calcined once in a reducing atmosphere furnace, and then calcined for a second time in an oxidizing atmosphere to obtain a highly active non-agglomerated α-alumina powder .

[0017] The specific operation steps are:

[0018] a: High-purity carbon black is modified with additives Tween and / or alcohol. The additives are water-soluble. The purpose of adding additives is to make carbon black well combined with aluminum salt in aqueous solution;

[0019] b: Dissolve high-purity aluminum salt in a nearly saturated solution at about 85°C, add polyethylene glycol as a surfactant, and add in an amount of 0.3% to 0.9%. The purpose of a...

Embodiment 1

[0025] Using aluminum ammonium sulfate as the raw material, firstly mix 150g of carbon black and 5g of Tween / 10g of alcohol in a high-speed disperser for 5 minutes, take it out and set aside. Take 1000g of ammonium aluminum sulfate and dissolve it in water (85°C) to obtain a nearly saturated solution, add 5g of polyethylene glycol, and then add the modified carbon black into it, stir evenly, put it in a water bath and cool slowly, the cooling speed -0.3°C / min, pour off the upper aqueous solution after cooling, take out the black crystals in the lower layer, and put them into the crucible. Then put it into a vacuum carbon tube furnace, and calcine in a hydrogen atmosphere at a calcination temperature of 1200°C for 1 hour. After the calcined powder is taken out, it is calcined in a muffle furnace (ventilated, oxidizing atmosphere) at 750°C for 1 hour to obtain the required high activity non-agglomerated α-alumina powder. The distribution of the obtained powder is narrow, betwee...

Embodiment 2

[0027] Use ammonium aluminum carbonate (synthesized by yourself) as raw material. First, stir and mix 200g of carbon black and 20g of Tween / 40g of alcohol in a high-speed disperser for 5 minutes, take it out and set aside. Dissolve 1000g of ammonium aluminum carbonate in water (85°C) to obtain a nearly saturated solution, add 8g of polyethylene glycol, and then add the modified carbon black into it, stir evenly, put it in a water bath for slow cooling, the cooling speed -1°C / min, pour off the upper aqueous solution after cooling, take out the black crystals in the lower layer, and put them into a crucible. Then put it into a vacuum carbon tube furnace, and calcine in a hydrogen atmosphere at a calcination temperature of 1300°C for 1 hour. After the calcined powder is taken out, it is calcined in a muffle furnace (ventilated, oxidizing atmosphere) at 750°C for 1 hour to obtain the required high activity non-agglomerated α-alumina powder. The distribution of the obtained powde...

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Abstract

The invention relates to an Alpha-alumina powder preparation method, which is used for preparing high active non-agglomeration Alpha-alumina powder of high-performance high-purity high-density alumina ceramic(such as ceramic ultrafiltration membrane). The invention is characterized in that: firstly the high purity aluminum salt is heated and dissolved, and then added with surfactant, and furthermore added with the modified high purity active carbon black, and stirred, cooled and crystallized to form a mixture of carbon black integrated aluminum salt crystal, and then the black mixture is sintered for first time in the reduction atmosphere furnace, and then sintered for secondary time in the oxidation atmosphere after sintered for the first time, so that the high active non-agglomeration Alpha-alumina powder is obtained. The invention adopts the two-step sintering technique, the aluminum salt is sintered in the reduction atmosphere to obtain the Alpha-alumina, the obtained Alpha-alumina crystal is surrounded by the carbon black, no agglomeration is generated, the invention has good active, narrow granular distribution, and complete crystal shape.

Description

technical field [0001] A method for preparing α-alumina powder, which relates to the preparation of a high-activity non-agglomerated α-alumina powder used for preparing high-performance, high-purity, and high-density alumina ceramics (such as ceramic ultrafiltration membranes, etc.) method. Background technique [0002] α-alumina powder is a chemical formula Al 2 o 3 And the compound with α crystal phase is widely used. At present, the α-alumina produced industrially is mainly made of aluminum hydroxide, alumina or a mixture of the two, mixed with an appropriate amount of additives, and then calcined in a guided flame kiln or tunnel kiln in one step. The particles calcined in this way have coarse crystals, high porosity and poor sintering performance. The particle size distribution of the ground powder is very wide, ranging from 1 μm to tens of μm, and the sintering activity is greatly reduced. During sintering High temperatures and sintering aids are required. This inc...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/30
Inventor 李晋峰陈玮梁莉娟
Owner 中铝郑州有色金属研究院有限公司
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