Method or adopting high-pressure phase-change method to prepare polycrystal alpha-aluminum oxide

A phase change method, alumina technology, applied in the field of inorganic non-metallic materials, can solve the problems of easy grain growth, difficult dispersion, adsorption, etc., to achieve the effect of high purity and single phase

Inactive Publication Date: 2017-06-13
HENAN UNIVERSITY OF TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to α-Al 2 o 3 The crystal grains tend to grow and lose their nanostructure at high temperature, and it is challenging to synthesize such fully dense nanopolycrystalline bulk materials,
[0005] The preparation of nano-polycrystalline ceramic materials mostly uses nano-powder as the initial material. The problems of agglomeration, adsorption, and difficulty in dispersion of nano-powder restrict the mechanical properties of polycrystalline materials obtained by sintering.

Method used

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  • Method or adopting high-pressure phase-change method to prepare polycrystal alpha-aluminum oxide

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] a. Raw material processing and testing: γ-Al with a purity of 99% and a grain size of 5 μm 2 o 3 The raw material is treated with absolute ethanol, and the waste liquid is poured out. The treated raw material is dried in an oven at 120°C; the dried raw material is added with deionized water as a binder, and pre-pressed; the molded sample is placed in vacuum drying Vacuum drying in an oven; through XRD and laser particle size determination, the crystal form of the raw material is tetragonal γ-Al 2 o 3 .

[0026] b. Assembling the sintering unit: wrap the pre-pressed raw material with metal inclusions to prevent the sample from being polluted under high temperature and high pressure; then put the wrapped pre-pressed raw material into a treated metal cup and put it into a high-pressure Assemble in the synthesis device, and then put the assembled sintering unit into a dry oven at a constant temperature of 120°C for standby; the sintering unit uses graphite tube as the he...

Embodiment 2

[0032] a. Raw material processing and testing: γ-Al with a purity of 99.5% and a grain size of 20 μm 2 o 3 The raw material is treated with absolute ethanol, and the waste liquid is poured out. The treated raw material is dried in an oven at 120°C; the dried raw material is added with deionized water as a binder, and pre-pressed; the molded sample is placed in vacuum drying Vacuum drying in an oven; through XRD and laser particle size determination, the crystal form of the raw material is tetragonal γ-Al 2 o 3 .

[0033] Step b of this embodiment is the same as that of Embodiment 1 and will not be repeated.

[0034] c. High-temperature and high-pressure sintering: Use a press to carry out high-temperature and high-pressure sintering. The sintering pressure is 5GPa. After the pressure reaches the set pressure, heat up and heat up. Under the condition of sintering temperature of 1500°C, the holding time is 50 minutes; after the holding is over, Turn off heat, and slowly star...

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Abstract

The invention relates to a method for adopting a high-pressure phase-change method to prepare polycrystal alpha-aluminum oxide. According to the method, gamma-aluminum oxide is adopted as a raw material, through purification treatment and prepressing forming of the raw material, and after assembly of a sintering unit, sintering is conducted on high-temperature and super-high pressure condition in which the temperature is 300-1500 DEG C and the pressure is 1-25 GPa, and a follow-up sample is then subjected to treatment and performance detection. According to the method for adopting the high-pressure phase-change method to prepare polycrystal alpha-aluminum oxide, gamma-aluminum oxide is directly converted into polycrystal alpha-aluminum oxide, and thus a polycrystal alpha-aluminum oxide material which is single in phase, uniform in structure, has good performance like high rigidity and density, and is high in purity can be prepared.

Description

technical field [0001] The present invention relates to the use of γ-Al 2 o 3 As the raw material, high-performance polycrystalline α-alumina (that is, α-Al 2 o 3 )Methods. It belongs to the field of inorganic non-metallic materials. [0002] technical background [0003] There are many isomorphic crystals of alumina, and there are more than 10 known at present, and there are mainly three crystal forms, namely α-Al 2 o 3 , β-Al 2 o 3 , γ-Al 2 o 3 . γ-Al 2 o 3 and α-Al 2 o 3 It is the main form of alumina. γ-Al 2 o 3 It belongs to the transition form of alumina, which is powdery, microspherical or columnar white solid. Its crystal structure is different from industrial alumina. α-Al 2 o 3 It is an important inorganic non-metallic material and the most stable phase among all aluminas. [0004] Nano α-Al 2 o 3 Polycrystalline, with good mechanical properties (high hardness, high toughness, high strength); fracture strength is α-Al 2 o 3 several times th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/10C04B35/111C04B35/622C04B35/645
Inventor 王海阔仝菲菲刘俊龙
Owner HENAN UNIVERSITY OF TECHNOLOGY
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