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Method for producing aluminum oxide powder used as a raw material for producing sapphire crystals by flame melt process

A technology of sapphire crystal and alumina powder, which is applied in the preparation of alumina/hydroxide, etc., can solve the problems of stable growth interference of sapphire crystal, difficulty in obtaining alumina raw materials, and large segregation of doping elements, etc. Stable growth, effective reduction of crystal defects, and pure crystal color

Inactive Publication Date: 2011-01-12
李振亚
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0018] There are several defects in the above traditional process: First, in the whole doping process, it is difficult to achieve uniform distribution of doping elements in alumina powder, and the composition segregation of doping elements in alumina powder is relatively large
In the subsequent production of sapphire crystals by flame melting, this component segregation will lead to various crystal growth defects during the crystal growth process; secondly, it is difficult to obtain real high-purity alumina raw materials by pyrolysis of ammonium aluminum sulfate
A large number of fluorine and sulfur ions remaining in the pyrolysis process, as well as sodium and potassium ions that are difficult to eliminate during the preparation process, will interfere with the stable growth of the sapphire crystal, resulting in the formation of a large number of crystal defects in the final sapphire crystal. Decrease the quality of the crystal, deteriorate the processing performance, even cause the crystal to burst, and reduce the availability; third, there will be a large amount of sulfur trioxide waste gas emitted during the pyrolysis production process, and these waste gases will be discharged into the atmosphere. Serious Environmental Pollution

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0039] First, 20 kg of high-purity remelted aluminum ingot with a purity of 99.993% is put into the graphite melting crucible of an intermediate frequency induction furnace for melting, and then high-purity iron filings (purity 99.9%) and aluminum High-purity titanium chips (99.99% pure) with an ingot weight of 0.001 at% were put into a melting crucible, and the resulting melt temperature was kept at 830°C for 2 hours. The melt was stirred continuously during the holding period.

[0040] Afterwards, the obtained melt is introduced into an atomizing nozzle and atomized and crushed with compressed air, and the atomized powder is cooled with high-purity water during the atomization process to obtain an atomized powder slurry. Atomization conditions: air pressure 2MPa, air flow 3m 3 / min. The resistivity of the high-purity water used for cooling is 12 MΩ·cm.

[0041] Subsequently, the slurry obtained by the aforementioned atomization was concentrated to a concentration of 20%, ...

Embodiment 2

[0046] Firstly, put 20 kg of high-purity remelted refined aluminum ingot with a purity of 99.999% into the graphite melting crucible of an intermediate frequency induction furnace to melt, and then put high-purity metal chromium chips (purity 99.9%) accounting for 2.5 at% of the weight of the aluminum ingot And put high-purity titanium chips (purity 99.99%) accounting for 0.008 at% of the weight of the aluminum ingot into the melting crucible, keep the temperature of the obtained melt at 930°C, and keep it warm for 0.5 hours. The melt was stirred continuously during the holding period.

[0047] Afterwards, the obtained melt is introduced into an atomizing nozzle and atomized and crushed with compressed air, and the atomized powder is cooled with high-purity water during the atomization process to obtain an atomized powder slurry. Atomization conditions are: air pressure 4MPa, air flow 4m 3 / min. The resistivity of the high-purity water used for cooling is 12 MΩ·cm.

[0048]...

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Abstract

The invention relates to a method for producing aluminum oxide powder, which is to product high-purity aluminum oxide powder by melting high-purity aluminum, atomizing and hydrolyzing. The aluminum oxide powder product prepared by the method has extremely high purity, and when used as a raw material for producing sapphire crystals by a flame melt process, can improve the transparency and color purity of the sapphire crystals effectively, reduce the defect rate of small sapphire crystals considerably and increase the volume of boule bars of the sapphire crystals produced by the flame melt process effectively. The method adopts a simple process flow, solves pollution problems such as waste gas emission and is environmentally-friendly.

Description

technical field [0001] The invention relates to a production method of alumina powder, in particular to a production method of alumina powder used as a raw material for producing sapphire crystals by a flame fusion method, which belongs to the preparation technology of alumina powder. Background technique [0002] High-purity alumina has many important uses, such as being used as a foundation and insulating material in the fields of electronics and optics industry, and it is usually obtained from bauxite through the Bayer process. However, alumina obtained from bauxite by the Bayer process does not meet the quality requirements for many applications. For example, for high-performance new ceramics, especially transparent alumina, it is necessary to use high-purity alumina raw materials to prepare, and the purity of raw materials is required to reach 99.999% or higher. [0003] As a kind of high-purity alumina, sapphire crystal, that is, α-alumina, one of its important uses i...

Claims

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Application Information

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IPC IPC(8): C01F7/30
Inventor 李振亚
Owner 李振亚
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