Method for growing mullite crystals through floating-zone method

A technology of mullite and floating zone method, which is applied in the directions of single crystal growth, crystal growth, single crystal growth, etc., can solve the problems of difficulty in obtaining centimeter-level mullite crystals, lack of research on mullite crystals, etc., and achieve repeatable Strong performance, low cost and simple operation

Inactive Publication Date: 2014-05-21
BEIJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, mullite has a melting point of 1850°C [49,50] , It is not easy to obtain centimeter-level mullite crystals by using traditional growth techniques. At the same time, there is a lack of research on mullite crystals at home and abroad. After a comprehensive comparison, it was decided to grow mullite crystals by optical floating zone method

Method used

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  • Method for growing mullite crystals through floating-zone method
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  • Method for growing mullite crystals through floating-zone method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] (1) Powder Al with a purity of up to 99.99% 2 o 3 and SiO with a purity of up to 99.999% 2 Weigh the ingredients according to the stoichiometric ratio of 3:2, use absolute ethanol as the dispersant to dilute and mix evenly, ball mill and dry, sieve through 200 mesh, and put the powder into Al 2 o 3 Place the crucible in a muffle furnace to pre-fire at a temperature of 1450°C for 15 hours at a constant temperature, then grind and sieve through a 200-mesh second time;

[0024] (2) Put the powder sieved twice in step (1) into a strip-shaped rubber balloon, compact and seal it, vacuumize it for 10 minutes, and press it for 15 minutes under isostatic pressure of 70MPa to make it uniform in density vegetative body.

[0025] (3) Put the green body obtained in step (2) into the muffle furnace for sintering again, and sinter at a constant temperature for 30 hours at a temperature of 1550° C. to obtain a dense polycrystalline rod.

[0026] (4) Put the polycrystalline rod pre...

Embodiment 2

[0029] (1) Powder Al with a purity of up to 99.99% 2 o 3 and SiO with a purity of up to 99.999% 2 Weigh the ingredients according to the stoichiometric ratio of 3:2, use absolute ethanol as the dispersant to dilute and mix evenly, ball mill and dry, sieve through 200 mesh, and put the powder into Al 2 o 3 Place the crucible in a muffle furnace for pre-firing at a temperature of 1500°C for 20 hours at a constant temperature, then grind and sieve through a 200-mesh sieve for the second time;

[0030] (2) Put the powder that has been sieved twice in step (1) into a strip-shaped rubber balloon, compact it and seal it, vacuumize it for 15 minutes, and press it for 10 minutes under the pressure of isostatic pressure 70MPa to make it uniform in density vegetative body.

[0031] (3) Put the green body obtained in step (2) into the muffle furnace for sintering again, and sinter at a constant temperature for 24 hours at a temperature of 1550° C. to obtain a dense polycrystalline rod...

Embodiment 3

[0035] (1) Powder Al with a purity of up to 99.99% 2 o 3 and SiO with a purity of up to 99.999% 2 Weigh the ingredients according to the stoichiometric ratio of 3:2, use absolute ethanol as the dispersant to dilute and mix evenly, ball mill and dry, sieve through 200 mesh, and put the powder into Al 2 o 3 Place the crucible in a muffle furnace for pre-firing at a temperature of 1450°C for 20 hours at a constant temperature, then grind and sieve through a 200-mesh sieve for the second time;

[0036] (2) Put the powder that has been sieved twice in step (1) into a strip-shaped rubber balloon, compact and seal it, vacuumize it for 15 minutes, and press it for 20 minutes under isostatic pressure of 65MPa to make it uniform in density vegetative body.

[0037] (3) Put the green body obtained in step (2) into the muffle furnace for sintering again, and sinter at a constant temperature for 25 hours at a temperature of 1600° C. to obtain a dense polycrystalline rod.

[0038] (4) ...

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Abstract

The invention discloses a method for growing mullite crystals through a floating-zone method, belonging to the field of crystal growth. The method comprises the following steps: dosing Al2O3 and SiO2 powder according to a stoichiometric ratio; ball-milling, drying, screening, pre-sintering and re-screening the dosed mixture; pressing the powder into rod-shaped material rods; sintering the prepared material rods in a muffle furnace, thereby obtaining dense and uniform polycrystalline rods; putting the polycrystalline rods into a floating zone furnace, raising the temperature at a rate of 50-100 DEG C per minute until the material rods and seed crystals are molten, butting, setting the crystal growth speed at 2-10mm/h after the melting zone is stabilized within 3-5 minutes, and starting crystal growth; setting the cooling parameters and cooling to room temperature after the growth is ended. The mullite crystals without macro defects are growth at the first time by using the floating-zone method, the crystal forming quality is high, and the growth speed is high.

Description

technical field [0001] The invention belongs to the field of mullite crystal growth, and in particular relates to a method for growing mullite crystals by a floating zone method. Background technique [0002] Mullite is a chain-like aluminosilicate mineral, its crystal structure is similar to line silica mineral, it belongs to orthorhombic system, its unit cell constant is a=0.574, b=0.768, c=0.288, it is currently used One of the most important materials in the field of traditional and advanced materials. Mullite has high refractoriness, high temperature strength, high elastic modulus, chemical corrosion resistance, oxidation resistance, creep resistance, excellent mechanical properties, good thermal stability, high softening temperature under load, electrical insulation It is an ideal refractory material and has been widely used in metallurgy, glass, ceramics, chemistry, electric power, national defense, gas and cement and other fields. [0003] As a new and efficient cr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C30B29/34C30B13/00
Inventor 蒋毅坚张春萍马云峰徐宏王越梅晓平
Owner BEIJING UNIV OF TECH
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