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Method for preparing silicon nitride-silicon dioxide gradient wave-transmitting composite ceramic

A technology of silica and multiphase ceramics, applied in the field of materials, can solve problems such as easy moisture absorption and influence on dielectric properties, and achieve the effect of improving mechanical properties and anti-moisture absorption performance

Inactive Publication Date: 2016-08-03
YANTAI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] In order to overcome the technical problem that the silicon nitride-based porous ceramics prepared in the prior art are easy to absorb moisture and affect the dielectric properties, the present invention provides a silicon nitride-silicon dioxide gradient wave-transparent composite phase prepared by using a directional sol impregnation process ceramic method

Method used

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  • Method for preparing silicon nitride-silicon dioxide gradient wave-transmitting composite ceramic
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  • Method for preparing silicon nitride-silicon dioxide gradient wave-transmitting composite ceramic

Examples

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Embodiment 1

[0024] The preparation process of the gradient silicon nitride-silicon dioxide composite ceramics of this embodiment is as follows figure 1 Shown:

[0025] 1. Mix silicon nitride powder with a particle size of 0.3 microns and phenolic resin at a ratio of 80:20 to make a mixed powder, pour the mixed powder into a ball mill tank, and add 300 ml of no Water ethanol, 15-25 alumina balls with a diameter of 8-12 mm, ball milled for 15-20 hours to make ceramic slurry. The prepared ceramic slurry is taken out and dried, then pulverized, passed through a 100-mesh sieve, poured into a mold, molded into a green body with a pressure of 100MPa, and sintered in air at 1250°C for 2 hours to obtain a porous silicon nitride with uniform microstructure —Silicon dioxide composite ceramics.

[0026] 2. Install the porous silicon nitride-silicon dioxide composite ceramics in the impregnation device, such as figure 2 shown. The impregnation device places the porous silicon nitride-silicon diox...

Embodiment 2

[0030] The preparation process of the gradient silicon nitride-silicon dioxide composite ceramics of this embodiment is as follows figure 1 Shown:

[0031] 1. Mix silicon nitride powder with a particle size of 0.1 micron and phenolic resin at a ratio of 90:10 to make a mixed powder, pour the mixed powder into a ball mill jar, and add 200 ml of Water ethanol, 15-25 alumina balls with a diameter of 8-12 mm, ball milled for 15-20 hours to make ceramic slurry. The prepared ceramic slurry is taken out and dried, then pulverized, passed through an 80-mesh sieve, poured into a mold, molded into a green body with a pressure of 80MPa, and sintered in air at 1200°C for 3 hours to obtain a porous silicon nitride with uniform microstructure —Silicon dioxide composite ceramics.

[0032] 2. Install the porous silicon nitride-silicon dioxide composite ceramics in the impregnation device, which has the same structure as the impregnation device used in Example 1. Adjust the temperature of t...

Embodiment 3

[0036] The preparation process of the gradient silicon nitride-silicon dioxide composite ceramics of this embodiment is as follows figure 1Shown:

[0037] 1. Mix silicon nitride powder with a particle size of 0.6 microns and phenolic resin at a ratio of 80:20 to make a mixed powder, pour the mixed powder into a ball mill jar, and add 250 ml of Water ethanol, 15-25 alumina balls with a diameter of 8-12 mm, ball milled for 15-20 hours to make ceramic slurry. The prepared ceramic slurry is taken out and dried, then pulverized, passed through a 60-mesh sieve, poured into a mold, molded into a green body with a pressure of 80MPa, and sintered in air at 1300°C for 2 hours to obtain a porous silicon nitride with uniform microstructure —Silicon dioxide composite ceramics.

[0038] 2. Install the porous silicon nitride-silicon dioxide composite ceramics in the impregnation device, which has the same structure as the impregnation device used in Example 1. Adjust the temperature of th...

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Abstract

The invention discloses a method for preparing silicon nitride-silicon dioxide composite ceramic with gradient silicon dioxide distribution.The gradient of a microstructure in the composite ceramic is gradually changed.The portion, on one side of the composite ceramic, of the microstructure is dense with few micropores while the portion, on the other side of the composite ceramic, of the microstructure is still of a porous structure.Through the gradient-changing microstructure, the moisture absorption resistance of the composite ceramic can be remarkably improved under the condition that the dielectric properties of the silicon nitride-silicon dioxide composite ceramic are not lowered, and the mechanical properties of the composite ceramic are further improved.By means of the method, the defect that due to a large quantity of exposed micropores, silicon nitride based porous ceramic prepared through a traditional process absorbs moisture in the storing and using process, and consequently the dielectric constant is increased can be overcome.

Description

technical field [0001] The invention belongs to the technical field of materials, and in particular relates to a method for preparing silicon nitride-silicon dioxide gradient wave-transmitting composite ceramics. Background technique [0002] Inorganic electromagnetic wave-transparent materials are widely used as radomes and antenna windows of launch vehicles, space shuttles, returnable satellites and various types of missiles due to their good high temperature resistance, impact resistance and mechanical properties. Silicon dioxide ceramics and silicon nitride ceramics are two very potential inorganic electromagnetic wave-transmitting materials. Silica ceramics have excellent dielectric properties, but poor mechanical properties, especially low strength and toughness limit their use as high-performance electromagnetic wave-transmitting materials. Silicon nitride ceramics have excellent mechanical properties, but the dielectric constant is high, which needs to be improved. ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/584C04B38/00
CPCC04B35/584C04B38/00C04B2235/3418C04B2235/75
Inventor 李向明李刚高明军
Owner YANTAI UNIV
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