Hollow spheroidal mullite material and preparation method thereof

A technology of mullite and mullite whiskers, which is applied in the field of hollow mullite spherical materials and its preparation, can solve the problems of difficulty in obtaining pure whiskers, cost dependence, and difficult control of conditions, and achieve good rolling filling The effect of high capacity, light weight and high porosity

Active Publication Date: 2019-08-30
CHANGAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although the above method can obtain good products, but because the above preparation process is complicated, the conditions are difficult to control, the cost of raw materials is high and resources are limited, it is difficult to obtain pure whiskers and depends on the cost issues involved in equipment

Method used

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  • Hollow spheroidal mullite material and preparation method thereof
  • Hollow spheroidal mullite material and preparation method thereof
  • Hollow spheroidal mullite material and preparation method thereof

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preparation example Construction

[0030] A kind of preparation method of mullite whisker hollow sphere material of the present invention comprises the following steps:

[0031] (1) Add silica sol, water and ethanol to the container in a volume ratio of 1:(4-9):(6-8), stir evenly, adjust the pH value to 2, and form silica sol;

[0032] After mixing alumina powder, aluminum fluoride trihydrate powder, and ethanol at a mass ratio of 1:(0.29-0.67):(3-9), wet milling with zirconia balls for 24-36 hours to make nano-alumina powder and trihydrate The particle diameters of the aluminum fluoride powder are all less than 2000nm to obtain a mixed slurry;

[0033] In the present invention, one or more of calcium aluminate, magnesium oxide, titanium oxide and chromium oxide can be added to promote sintering. Calcium aluminate accounts for 0.1-5% of the solid content of the mixed slurry, magnesium oxide accounts for 0.1-1.2% of the solid content of the mixed slurry, titanium oxide accounts for 0.1-2.0% of the solid content...

Embodiment 1

[0043] (1) Add silica sol, water and ethanol into the container at a volume ratio of 1:4:6, stir evenly, adjust the pH value to 2, and form silica sol A; add alumina powder, aluminum fluoride trihydrate Powder and ethanol were mixed at a mass ratio of 1:0.29:3, and wet milled with zirconia balls for 24 hours. The particle diameters of nano-alumina powder and aluminum fluoride trihydrate powder were both 50nm, and a mixed slurry S was obtained; Calcium aluminate is added to S, and the calcium aluminate accounts for 3% of the solid content of the mixed slurry S to promote sintering.

[0044] (2) Mix the silica sol A and the mixed slurry S in step (1) uniformly at a volume ratio of 1:0.5 to obtain the mullite precursor composite slurry, and then add the coagulant ammonia water to compound the mullite precursor The pH value of the slurry is 7, and it gels in the container to obtain a composite block;

[0045] (3) The composite block was naturally dried at room temperature for 20 ...

Embodiment 2

[0050] (1) Stir the silica sol, water and ethanol in a container at a volume ratio of 1:5:6, adjust the pH value to 2 to form silica sol A; mix alumina powder, aluminum fluoride trihydrate, ethanol After mixing according to the mass ratio of 1:0.35:4, wet milling with zirconia balls for 28 hours, the particle diameters of nano-alumina powder and aluminum fluoride trihydrate powder are both 100nm, and mixed slurry S is obtained; Magnesium oxide, and magnesium oxide accounts for 1% of the solid content of the mixed slurry S, to promote sintering.

[0051] (2) Mix the silica sol A and the mixed slurry S in step (1) uniformly at a volume ratio of 1:0.8 to obtain the mullite precursor composite slurry, and then add the coagulant ammonia water to compound the mullite precursor The pH value of the slurry is 7, and the composite block is obtained by gelling in the container;

[0052] (3) The composite block was naturally dried at room temperature for 40 h, and then heated at 70° C. f...

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Abstract

The invention provides a hollow spheroidal mullite whisker material and a preparation method thereof. The preparation method comprises steps as follows: silica sol, water and ethanol are added to a container and stirred uniformly, the pH value is regulated to 2, and silica sol is formed; alumina powder, aluminum fluoride trihydrate and ethanol are mixed and subjected to ball milling, and mixed slurry is obtained; the silica sol and the mixed slurry are mixed uniformly in a volume ratio of 1:(0.5-1.4), the pH value is regulated to 7-9, gelatinization is performed, and precursor powder is obtained; a polyvinyl alcohol solution is uniformly sprayed to the surfaces of polystyrene spheres, starch spheres, phenol-formaldehyde resin spheres or urea spheres, then the spheres are put in the precursor powder to adhere to the precursor powder, the operation is repeated multiple times, then ball milling, drying and calcining are performed in sequence, and the hollow spheroidal mullite whisker material is obtained. According to the hollow spheroidal mullite whisker material, the volume density is 0.34-0.85 g/cm<3>, the room-temperature thermal conductivity is 0.184-0.485 W/(m<-1>.K<-1>), and the open porosity is 62.33%-81.86%.

Description

technical field [0001] The invention belongs to the field of inorganic non-metallic materials, and in particular relates to a hollow mullite spherical material and a preparation method thereof. Background technique [0002] Mullite is a two-phase solid solution material with high temperature resistance, excellent thermal shock resistance, chemical stability, low thermal conductivity, etc. It is used in high temperature protective coatings, industrial furnace linings and ceramic proppants for oil exploration and other fields. Existing mullite materials mainly include particles, fibers and whiskers. The mullite formed by the particles has a large shrinkage rate during the sintering process, resulting in a decrease in porosity. Mullite fibers are calcined to form porous mullite, which has the problem of low strength. Compared with granular and fibrous polycrystalline mullite, the whisker-like mullite material is more similar to a single crystal structure, which significantly...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B38/06C04B35/185C04B35/622C04B35/626
CPCC04B38/067C04B35/185C04B35/622C04B35/62605C04B2235/6562C04B2235/6567C04B2235/661C04B2235/77C04B2235/9607C04B38/0074C04B38/0067
Inventor 李红伟高莹曾德军吴明明
Owner CHANGAN UNIV
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