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Method for preparing aluminum oxide/mullite foamed ceramic

A technology of foam ceramics and mullite, which is applied in the field of porous ceramic materials, can solve the problems of easy collapse of the green body, low strength of the green body, and difficult demoulding, etc., and achieve a structure without shrinkage, deformation, high strength, and easy demoulding Effect

Inactive Publication Date: 2015-04-08
AEROSPACE INST OF ADVANCED MATERIALS & PROCESSING TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The thermoplastic (or thermosetting) polymer curing method has weak molding force, and the free radical chemical reaction of the monomer in the gel injection molding method is very sensitive to the oxygen contained in the foam, resulting in a weaker strength of the formed foam ceramic body. Low, the green body is prone to collapse and difficult to demould

Method used

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  • Method for preparing aluminum oxide/mullite foamed ceramic
  • Method for preparing aluminum oxide/mullite foamed ceramic

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] Add α-Al to 30% concentration silica sol 2 o 3 Powder (purity: 99.9%) and ammonium citrate dispersant and sodium carboxymethylcellulose, of which Al 2 o 3The mass content of the powder is 60%, the addition of dispersant and sodium carboxymethyl cellulose is 1% (based on the mass of alumina powder), and after mixing the mixture for 5 hours in a high-speed ball mill, add 2% foaming agent, high-speed mechanical stirring for 30 minutes to fully foam until a uniform and stable foam slurry is formed, inject the foam slurry into the mold, and then keep warm in liquid nitrogen for 30 minutes before demoulding. The sample after demoulding is placed in an oven Dry thoroughly. In this process, the sample is easy to demould after curing, and the foam sample has no cracking, deformation and collapse during drying, and the linear shrinkage rate is <1%. The dried samples were heated up to 1650°C at a rate of 5°C / min in a nitrogen atmosphere for sintering, and kept for 2 hours to o...

Embodiment 2～4

[0040] Add α-alumina powder (purity: 99.9%) to 30% silica sol, the powder mass content is 40%, 50% and 70% respectively, plus 1% citric acid amine dispersant and carboxymethyl Sodium cellulose, ball mill and mix the material in a high-speed ball mill for 5 hours, then add 2% foaming agent to the slurry, stir at a high speed for 30 minutes to fully foam until a uniform and stable foam is formed, inject the foam slurry into the mold respectively, and place in liquid nitrogen Insulated for 30 minutes, the demoulded sample was thoroughly dried in an oven, and the dried sample was sintered in an air furnace at a rate of 3 °C / min to 1650 °C, and kept for 2 hours to obtain alumina / mullite foam ceramics. The shrinkage, density and strength of the sintered body are shown in Table 1.

[0041] Table 1

[0042]

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Abstract

The invention provides a method for preparing aluminum oxide / mullite foamed ceramic. The method is characterized in that a silicon sol and Al2O3 fine powder are mixed; nanometer SiO2 colloid particles in the silicon sol can be attached on the surfaces of Al2O3 particles to achieve single-layer saturation distribution; colloidal particles fill clearances of the Al2O3 particles by full contact; the silicon sol is gelatinized under the low temperature to generate a Si-O-Si lattice space structure for achieving the curing and forming of foamed slurry; after being cured, the ceramic foams can be directly heated and dried without independent drying or rubber discharging links and then are roasted at the high temperature to obtain the aluminum oxide / mullite foamed ceramic. According to the method, the process operation is simple, and the conditions are easily controlled; a produced green body is small in shrinkage and deformation during forming and drying; the yield of the aluminum oxide / mullite foamed ceramic is high; the production cycle is short; the production cost is low; mass production is achieved.

Description

technical field [0001] The invention relates to a method for preparing alumina / mullite foam ceramics, belonging to the technical field of porous ceramic materials. Background technique [0002] Alumina foam ceramics have a series of excellent properties such as high temperature resistance, corrosion resistance, light weight, etc., and are widely used in the purification process, catalyst carrier, burner, sound absorption and environmental protection in the production of aluminum and aluminum alloys. At present, the main reasons that restrict the excellent performance of alumina foam ceramics are the high thermal expansion coefficient of alumina and poor high temperature mechanical properties. [0003] Mullite has the characteristics of low density, good high temperature mechanical properties, low thermal expansion coefficient, thermal and chemical stability, and poor normal temperature mechanical properties. Alumina has good mechanical properties at room temperature. If alu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B38/02C04B35/14C04B35/10C04B35/622
Inventor 余娟丽吕毅赵英民郭世峰裴雨辰
Owner AEROSPACE INST OF ADVANCED MATERIALS & PROCESSING TECH
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