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Method for producing porous ceramic materials by adopting low-temperature hydrothermal method

A technology of porous ceramics and hydrothermal method, which is applied in the direction of ceramic products, applications, household appliances, etc., can solve the problems of lowering the liquid phase point of sintering aids, increasing the difficulty of manufacturing precision ceramic parts, and reducing the mechanical properties of porous materials, etc., to achieve water The effect of low heat

Inactive Publication Date: 2009-11-04
BEIHANG UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The previous method of preparing porous ceramics was mostly sintered at a temperature of 1300°C-1600°C with silica as the main sintering aid. This method has certain problems: (1) In order to reduce the liquid phase of the sintering aid point, added additives such as Al 2 o 3 , MgO, etc. have a great influence on the dielectric properties of porous bodies
The sintering aid forms a liquid phase during the sintering process, which is unfavorable for controlling and improving the porosity of the porous body
(2) For non-oxide ceramics, during the sintering process, oxidation reactions will occur, which will reduce the mechanical properties of porous materials
(3) During the sintering process, the size of the molded body will change to a certain extent. After sintering, secondary processing is required, which increases the difficulty of manufacturing precision ceramic parts

Method used

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  • Method for producing porous ceramic materials by adopting low-temperature hydrothermal method
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  • Method for producing porous ceramic materials by adopting low-temperature hydrothermal method

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preparation example Construction

[0042] In the preparation method of the present invention, ceramic porous materials with different porosities and strengths can be prepared by adjusting technological conditions such as sol concentration, hydrothermal conditions, and particle gradation of ceramic powder in the molded body.

[0043] The porosity of the porous ceramic material prepared by the invention is 30-50%.

[0044] The bending strength of the porous ceramic material prepared by the invention is 20-80MPa.

[0045] The dielectric constant of the porous ceramic material prepared by the invention is 3.2-3.8.

Embodiment 1

[0047] Low-temperature hydrothermal preparation of silicon nitride porous material with a porosity of 45% has the following steps:

[0048] The first step: preparation of ceramic molded body

[0049] First, mix evenly α-silicon nitride powder with a median particle size of 0.5 μm, β-silicon nitride powder with a median particle size of 11 μm, and deionized water to prepare the first intermediate;

[0050] Adding ammonia water with a concentration of 2 mol / L to the first intermediate to adjust the pH of the first intermediate to 9, thereby preparing the second intermediate;

[0051] Add acrylic acid amine to the second intermediate and make the third intermediate after ball milling for 120 minutes; the ball milling speed is 300r / min;

[0052] Add silica sol to the third intermediate, stir and degas under vacuum, inject into the mold, put it into a drying temperature of 80±5°C, dry for 30 minutes, and demould to obtain a ceramic molded body;

[0053] Dosage: Add 130g of α-sili...

Embodiment 2

[0068] Low-temperature hydrothermal preparation of silicon nitride porous material with a porosity of 35.5% has the following steps:

[0069] The first step: preparation of ceramic molded body

[0070] First, uniformly mix α-silicon nitride powder with a median particle size of 0.5 μm, β-silicon nitride powder with a median particle size of 1 μm, and deionized water to prepare the first intermediate;

[0071] Adding ammonia water with a concentration of 2 mol / L to the first intermediate to adjust the pH of the first intermediate to 10, thereby preparing the second intermediate;

[0072] Add acrylic acid amine to the second intermediate and make the third intermediate after ball milling for 180 minutes; the ball milling speed is 300r / min;

[0073] Add silica sol to the third intermediate, stir and degas under vacuum, inject into the mold, put in the drying temperature of 80±5°C, dry for 50 minutes, and demould to obtain a ceramic molded body;

[0074] Dosage: Add 172g of α-si...

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Abstract

The invention discloses a method for producing porous ceramic materials by adopting the low-temperature hydrothermal method. The method utilizes the hydrothermal reaction to immerse a ceramic formed body in silicon dioxide sol; according to the dissolution-precipitation mechanism, part of silicon dioxide particles can be precipitated on the surfaces of ceramic grains to play a bonding role, thereby producing the porous ceramic materials. The hydrothermal temperature in the preparation method is lower and can not cause the oxidation of non-oxide ceramics during the sintering process.

Description

technical field [0001] The invention relates to the field of low-temperature preparation of ceramic porous materials, and more particularly refers to a new method for preparing ceramic porous materials under low-temperature hydrothermal conditions. Background technique [0002] Porous ceramic is a new type of ceramic material, which has the advantages of low density, high porosity, corrosion resistance, high temperature resistance and long service life. It can be used normally in a large temperature range and can be used as an ideal new high-performance wave-transparent candidate material. The presence of higher porosity effectively reduces the dielectric constant of the ceramic material. The previous method of preparing porous ceramics was mostly sintered at a temperature of 1300°C-1600°C with silica as the main sintering aid. This method has certain problems: (1) In order to reduce the liquid phase of the sintering aid point, added additives such as Al 2 o 3 , MgO, etc...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/622C04B35/584C04B38/00
Inventor 张跃李昂谢春燕
Owner BEIHANG UNIV
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