High purity alumina polycrystal block for growing sapphire crystals and preparation method thereof

A technology of high-purity alumina and sapphire crystals, applied in the field of preparation of a-Al2O3 polycrystalline blocks, can solve problems such as increased production costs and insufficient equipment utilization, and achieve increased productivity, improved crystal growth quality, and increased sintered density Effect

Inactive Publication Date: 2013-02-27
SHANGHAI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Insufficient utilization of equipme

Method used

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Examples

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Effect test

Embodiment 1

[0021] A method for preparing a high-purity alumina polycrystalline block for growing sapphire crystals, comprising the steps of:

[0022] a. Commercial high-purity 5N (99.999%) a-Al produced by the aluminum alkoxide method 2 o 3 The powder is used as the raw material, filled in a self-made rubber barrel-shaped mold with a diameter of 150 mm and a height of 130 mm, sealed, and pressed in an isostatic press with a pressure of 150 Mpa for 2 minutes for cold isostatic pressing; Demoulding to obtain a cylindrical green body;

[0023] b. Cylindrical green bodies are sintered in air, the sintering temperature range is 1650°C, and the sintering time is 5 hours; the diameter is 120 mm, the height is 80 mm, and the density is 3.67g / cm 3 , a-Al with a relative density greater than 90% 2 o 3 Polycrystalline blocks.

[0024] The a-Al prepared in this embodiment 2 o 3 The polycrystalline block material is first pressed by cold isostatic pressing process, the equipment used is cold i...

Embodiment 2

[0026] This embodiment is basically the same as Embodiment 1, especially in that:

[0027] In this example, the a-Al prepared in step b 2 o 3 The diameter of the polycrystalline block reaches 200 mm, which can be used to match the existing 30kg sapphire single crystal crucible (inner diameter F218mm), and the maximum filling rate at one time can reach more than 90%. That is, using this crucible, it is expected to be able to grow a sapphire crystal up to 45 kg. a-Al prepared by this embodiment 2 o 3 Polycrystalline bulk materials are mainly used as raw materials for the growth of large-scale single crystal sapphire, which is similar to single crystal sapphire Al 2 o 3 have exactly the same crystal structure and chemical composition.

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Abstract

The invention discloses a preparation method of a high purity alumina polycrystal block for growing sapphire crystals, comprising the following steps: using commercial high-purity 5N(99.999%)a-Al2O3 powder as an initial raw material and filling the initial raw material into self-made tubby rubber molds with different diameters, sealing, keeping the pressure of 100-200 MPa in an isostatic pressing gauge for 1-5 min to conduct isostatic cool press forming; demolding to obtain a cylindrical biscuit; then sintering the cylindrical biscuit in air, vacuum or nitrogen environment with the sintering temperature of 1550-1750 DEG C and the sintering time of 2-5h to obtain an a-Al2O3 polycrystal block having the relative density of larger than 90% and the density of larger than 3.6g/cm. According to the invention, the a-Al2O3 polycrystal block prepared by the method is mainly used as a growing raw material for large-size single-crystal sapphire, has exactly the same crystal structure and chemical composition as single-crystal sapphire Al2O3; and the method can eliminate the secondary pollution problem in the preparation process of the a-Al2O3 polycrystal block.

Description

technical field [0001] The invention relates to a special ceramic preparation process, in particular to an a-Al 2 o 3 The preparation method of polycrystalline block, the a-Al prepared by the present invention 2 o 3 Polycrystalline blocks are used as substrate materials for GaN-based LEDs to achieve high efficiency, ultra-high brightness, and full color LEDs. Background technique [0002] Light-emitting diode (LED), as a semiconductor lighting source, has the characteristics of low power consumption, long life, and strong controllability. It is becoming another revolution in lighting sources after incandescent lamps and fluorescent lamps in the history of lighting. Since the 1990s, many breakthroughs have been made in the research and development of LED chip and material manufacturing technology. In 1991, Nakamura et al. of Nichia Company successfully developed a Mg-doped homojunction GaN blue LED, and GaN-based LEDs have been rapidly developed. Since then, it has become...

Claims

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Application Information

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IPC IPC(8): C01F7/46
Inventor 杨秋红陆神洲张浩佳
Owner SHANGHAI UNIV
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