Process for producing stephanoporate Si3N4

A -si3n4, ceramic technology, applied in the preparation of Si3N4 ceramics, can solve the problem of low porosity of ceramics, and achieve the effects of simple process, low dielectric constant and good permeability

Active Publication Date: 2009-08-19
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] The present invention prepares porous Si in order to solve prior art 3 N 4 The problem

Method used

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  • Process for producing stephanoporate Si3N4
  • Process for producing stephanoporate Si3N4
  • Process for producing stephanoporate Si3N4

Examples

Experimental program
Comparison scheme
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specific Embodiment approach 1

[0013] Specific implementation mode 1: Porous Si in this implementation mode 3 N 4 The preparation method of ceramics is realized according to the following steps: one, by mass percentage, 30~99.5% α-Si 3 N 4 Mix the powder and 0.5% to 70% sintering aid evenly; 2. Add the mixture prepared in step 1 to a polyvinyl alcohol solution with a mass concentration of 0.5% to 10%, and ball mill and mix for 1 to 12 hours to make slurry; 3. Put The mud prepared in step 2 is frozen at -170°C to -5°C for 1 to 72 hours, and then left to stand for 1 to 10 days at the same temperature and with a vacuum degree of less than 5Pa to obtain a green body; 4. The green body obtained in step 3 Bulk Si 3 N 4 Mixed powder with BN for burial, Si 3 N 4 The weight ratio to BN is 1:1, and then in nitrogen with a pressure of 0.1-100Mpa, the temperature is raised to 1500-2200°C at a heating rate of 5-200°C / min, kept for 1-72h, and cooled to room temperature with the furnace, that is Porous Si 3 N 4 c...

specific Embodiment approach 2

[0019] Specific embodiment two: the difference between this embodiment and specific embodiment one is that in step one, 70-95% of α-Si 3 N 4 Mix the powder and 5% to 30% sintering aid evenly. Others are the same as in the first embodiment.

specific Embodiment approach 3

[0020] Embodiment 3: This embodiment differs from Embodiment 1 or Embodiment 2 in that the particle size of the sintering aid in step 1 is 0.1-50 μm. Others are the same as in the first or second embodiment.

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Abstract

A porous Si3N4 ceramics preparation method solves the problem of low porosity of porous Si3N4 ceramics prepared by the prior art. The method is as follows: mixing alpha-Si3N4 powder and combustion assistant evenly; making the mixture and aqueous polyvinyl alcohol solution into slurry; refrigerating the slurry until the slurry completely freezes; carrying out low-temperature vacuum dehydration; moulding the slurry to green body with various shapes based on requirement before refrigeration; and sintering the dried green body to obtain porous Si3N4 ceramics. The porous Si3N4 ceramics prepared by the method have adjustable pore diameter and porosity which can reach as high as 95%. Process of the method is simple with good repeatability.

Description

technical field [0001] The present invention relates to a Si 3 N 4 Methods of preparation of ceramics. Background technique [0002] Porous ceramics generally have the characteristics of light weight, heat insulation, heat resistance, and corrosion resistance, and are widely used in fields such as filtration, catalysis, sound absorption, gas sensing, and artificial bones. Compared with oxide-based porous ceramics, porous Si 3 N 4 Ceramics have high strength, low and stable dielectric constant, and have application prospects as a new type of "structure-function" integrated material in the military electronics industry, which has attracted extensive research. [0003] Porous Si 3 N 4 Ceramic methods include non-full-dense sintering method and template method. [0004] Porous Si prepared by non-full-dense sintering method 3 N 4 Ceramics are usually α-Si 3 N 4 Powder is used as raw material, and a certain amount of additives are used at the same time, including Al 2 ...

Claims

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Application Information

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IPC IPC(8): C04B38/00C04B35/584C04B35/622
Inventor 叶枫刘利盟张敬义张海礁
Owner HARBIN INST OF TECH
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