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Flaky alpha-alumina crystals with large aspect ratio and a preparation method of the same

An alumina and flake technology, which is applied in the field of large aspect ratio flake α-alumina crystal and its preparation, can solve the problems of low aspect ratio, inability to display the excellent characteristics of pearlescent pigment matrix, large flake crystals, etc.

Active Publication Date: 2009-09-23
KOREA RES INST OF CHEM TECH +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0013] However, conventional flaky crystals have a relatively low large aspect ratio due to their large thickness, and thus cannot exhibit excellent properties as a matrix for pearlescent pigments

Method used

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  • Flaky alpha-alumina crystals with large aspect ratio and a preparation method of the same
  • Flaky alpha-alumina crystals with large aspect ratio and a preparation method of the same

Examples

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preparation example Construction

[0020] Further, the present invention relates to a method for preparing flaky α-alumina crystals, comprising:

[0021] (a) Prepare an aqueous metal precursor solution, which is obtained by mixing an aqueous aluminum precursor solution containing a water-soluble flux with an aqueous precursor solution containing 0.05-5 parts by weight of a zinc precursor and 0.01-0.5 parts by weight of a tin precursor, wherein the weight The parts are relative to 100 parts by weight of the aluminum precursor;

[0022] (b) titrate the aqueous metal precursor solution with a sodium salt solution to adjust the pH to 6.0-7.5, and perform hydrolysis to prepare a mixed gel;

[0023] (c) pretreating the hybrid gel by aging the hybrid gel at 60-100° C. for 5-30 hours, and drying the aged hybrid gel;

[0024] (d) drying the pretreated mixed gel at 60-200° C. for 5-30 hours;

[0025] (e) crystallizing the dried mixed gel at 850-1300° C. for 1-8 hours to prepare a cake mixed with flaky α-alumina crystal...

Embodiment 1

[0056] By mixing 670 g of aluminum sulfate (Al 2 (SO 4 ) 3 18H 2 O), 345g sodium sulfate (Na 2 SO 4 ), 280g potassium sulfate (K 2 SO 4 ), 4.8g 34% zinc sulfate (ZnSO 4 ·7H 2 O) aqueous solution and 1.0 g of 17% zinc sulfate (ZnSO 4 ·7H 2 O) Aqueous solution to prepare a homogeneous mixed solution. By dissolving 324g of sodium carbonate (Na 2 CO 3 ) and 2.7g sodium phosphate ((NaPO 3 ) 6 ) to prepare an alkaline solution. While stirring, the aluminum sulfate mixed solution (65° C.) was titrated with an alkali solution at a rate of 25 ml / min to adjust the final pH to 6.8 to prepare a gel mixed with pseudoboehmite and flux. The mixed silica gel was aged at 90°C for 20 hours, vacuum distilled at 60°C, and dried at 110°C for 20 hours. Flaky α-alumina crystals were prepared by pulverizing the dried mixed gel to less than about 5 mm, followed by crystallization in an alumina crucible (2 L) at 1200° C. for 7 hours. The flux was separated from the flaky α-alumina crys...

Embodiment 2

[0059] Transparent flaky α-alumina crystals were prepared as in Example 1 except that 0.5 g of 17% stannous sulfate was used.

[0060] The prepared flaky α-alumina crystals were confirmed to have an average particle thickness of 0.2 μm and an average particle size of 32.8 μm. Atomic analysis showed that it contained 0.4 parts by weight of zinc oxide and 0.04 parts by weight of tin oxide.

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Abstract

The present invention relates to flaky alpha-alumina crystals with large aspect ratio and its preparation method, and particularly to flaky alpha-alumina crystals comprising aluminum oxide, zinc oxide and tin oxide, which are prepared by obtaining a mixed gel which are prepared by obtaining a mixed gel by means of hydrolysis of an aqueous aluminum precursor solution comprising aqueous flux, aqueous zinc precursor solution and tin precursor aqueous solution, followed by aging, drying and crystallization processes. The crystals herein have an average particle thickness of 0.5 [mu]m or less, an average particle diameter of 30 [mu]m or higher and an aspect ratio of 100 or higher, thus being useful as a substrate of high quality pearlescent pigments, an abrasive, ceramic material and a filling material.

Description

[technical field] [0001] The present invention relates to a flaky α-alumina crystal having a large aspect ratio and a method for preparing the same, and in particular to a flaky α-alumina crystal comprising alumina, zinc oxide and tin oxide, which is obtained by hydrolysis The aqueous solution of the aluminum precursor, the aqueous solution of the zinc precursor and the aqueous solution of the tin precursor containing the water-soluble flux are then aged, dried and crystallized to prepare a mixed gel. The crystal has an average particle thickness equal to or less than 0.5 μm or less, an average particle diameter equal to or greater than 30 μm, and an aspect ratio equal to or greater than 100, so it can be used as a high-quality pearlescent pigment, abrasive, ceramic Matrix of materials and fill materials. [Background technique] [0002] Ceramic refers to a non-metallic inorganic solid material prepared by heat treatment at high temperature, and it has excellent fire resista...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/02C01F7/441
CPCC01F7/34C01P2004/54C01F7/441C01P2002/72C01P2004/20C09C1/407C01P2006/80C01P2004/61Y10T428/2982C01F7/02C04B35/10
Inventor 李正敏徐廷权朴昞基崔东旭张吉琓林光永赵晟伦姜光中
Owner KOREA RES INST OF CHEM TECH
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