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Method for preparing Si3N4/BAS foamed ceramic material

A foamed ceramic and slurry technology, which is applied in the field of porous ceramic materials, can solve the problems of low strength of foamed ceramic body, easy collapse of the body, poor formability of the foamed body, etc. Highly active effect

Active Publication Date: 2015-04-08
AEROSPACE INST OF ADVANCED MATERIALS & PROCESSING TECH
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  • 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 reaction of the monomer in the gel injection molding method is very sensitive to oxygen. Oxygen in the foam will affect the molding of the foam slurry by gel injection molding force, resulting in poor foam formability
The above reasons lead to the low strength of the molded foam ceramic body, which is prone to collapse and difficult to demould, which makes foam solidification molding a bottleneck problem restricting the development of foam ceramics.

Method used

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  • Method for preparing Si3N4/BAS foamed ceramic material
  • Method for preparing Si3N4/BAS foamed ceramic material
  • Method for preparing Si3N4/BAS foamed ceramic material

Examples

Experimental program
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Effect test

Embodiment 1

[0041] Add silicon nitride powder, barium oxide powder, aluminum oxide powder and a small amount of tetramethylammonium hydroxide dispersant to the silica sol to prepare slurry, wherein the addition of barium oxide and aluminum oxide is based on the mass of silicon dioxide in the silica sol As a benchmark, according to the stoichiometric ratio BaO-Al 2 o 3 -2SiO2 2 Add, the total solid phase (sum of silicon dioxide quality in silicon nitride powder, barium oxide powder, aluminum oxide powder and silica sol) content in the slurry is 55%, and the mass ratio of silicon nitride powder and BAS is 80 : 20; after ball milling mixing 5h in the high-speed ball mill, add 2% (taking solid phase gross mass as benchmark) foaming agent in the slurry, high-speed mechanical stirring 30min is fully foamed, until forming uniform and stable foam, will The foam slurry was injected into the mold, and then kept in liquid nitrogen for 30 minutes, and the sample after demoulding was thoroughly drie...

Embodiment 2～5

[0044] Add silicon nitride powder (Tsinghua Unigroup, Beijing), barium oxide powder, and alumina powder to the silica sol, wherein the addition of barium oxide and alumina is based on the quality of silicon dioxide in the silica sol, according to the stoichiometric ratio BaO-Al 2 o 3 -2SiO2 2 Add, the total solid phase (sum of silicon dioxide quality in silicon nitride powder, barium oxide powder, aluminum oxide powder and silica sol) content in the slurry is respectively 65%, 50%, 45% and 40%, nitrogen The mass ratio of silica powder and BAS is 90:10; then add 1% dispersant (tetramethylammonium hydroxide) and 1% sodium carboxymethyl cellulose, and use a high-speed ball mill to mix the mixture for 5 hours. After the slurry is degassed Inject into the mold, and then keep warm in liquid nitrogen for 20 minutes to fully solidify the slurry and demould. After freezing and demolding, the sample is heated to 80°C and kept warm to dry the sample thoroughly; after the sample is form...

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Abstract

The invention provides a method for preparing a Si3N4 / BAS foamed ceramic material. The method is characterized in that a silicon sol is used as a liquid phase for preparing slurry; silicon nitride powder, barium oxide powder, aluminum oxide powder, and few dispersing agents and adhesives are added, and the quantity of added barium oxide and aluminum oxide references to the mass of silicon dioxide in the silicon sol; the materials are added in stoichiometric ratio of BaO-Al2O3-2SiO2 to prepare the slurry; the materials are mechanically agitated to be foamed, and then silicon sol is frozen at the low temperature for gelatinization so as to enable the ceramic foams to be quickly cured and formed, thus obtaining Si3N4 / BAS foamed ceramic.

Description

technical field [0001] The invention relates to a method for preparing Si 3 N 4 The method for the / BAS foam ceramic material belongs to the technical field of porous ceramic materials. Background technique [0002] In addition to the basic characteristics of ceramics such as high temperature resistance, wear resistance, corrosion resistance and good thermal shock resistance, porous ceramics also have high porosity and low density, and the dielectric properties of materials can be adjusted by changing the porosity. Therefore, it has great application space in aerospace wave transmission and heat insulation materials. [0003] Silicon nitride ceramics are one of the materials with the best comprehensive performance in structural ceramics. Silicon nitride ceramics have the advantages of high strength, high hardness (Mohs hardness is 9), low high temperature creep, low thermal conductivity, small thermal expansion coefficient, good thermal shock resistance, stable chemical p...

Claims

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Application Information

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IPC IPC(8): C04B38/02C04B35/584C04B35/624
Inventor 余娟丽王涛吕毅赵英民郭世峰裴雨辰
Owner AEROSPACE INST OF ADVANCED MATERIALS & PROCESSING TECH
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