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A kind of low shrinkage porous silicon nitride ceramics and preparation method thereof

A technology of silicon nitride ceramics and low shrinkage, which is applied to ceramic products, other household appliances, household appliances, etc., can solve problems such as large shrinkage, and achieve the effect of reducing excessive shrinkage and eliminating directionality

Active Publication Date: 2020-07-31
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] In order to obtain porous silicon nitride ceramics with controllable porosity, the present invention solves the problem of relatively large shrinkage in the sintering process in the prior art, and provides a method for preparing porous silicon nitride ceramics with low shrinkage rate. Include the following steps:

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] Step 1: Mix α-silicon nitride, alumina, and yttrium oxide at a mass ratio of 93:2:5, and use silicon nitride balls and absolute ethanol as ball milling media. After wet mixing for 12 hours, dry with nitrogen Sieve to obtain a uniform mixed powder;

[0031] The second step: add deionized water and dispersant A to the mixed powder described in the first step to obtain a uniform and stable water-based ceramic slurry, wherein the dispersant A is sodium polyacrylate, and the dispersant A accounts for 0.5% of the mass of the mixed powder, the solid content of the slurry in the water-based ceramic slurry is 20vol%;

[0032] The third step: put the water-based ceramic slurry in the second step into the oil phase through vibration dripping, so that the water-based ceramic slurry forms microspherical droplets in the oil phase, and freeze it through the freezing medium , filter and separate the solidified ceramic microspheres from the oil phase, and use ethyl acetate to repeatedl...

Embodiment 2

[0040]The difference between this example and Example 1 is that the first step is, after mixing α-silicon nitride, aluminum oxide, and yttrium oxide, and then wet mixing them at a mass ratio of 90:3:7 for 12 hours, nitrogen Dry and sieve to obtain a uniform mixed powder, and the others are the same as in Example 1.

Embodiment 3

[0042] The difference between this example and Example 1 is that the dispersant A in the second step is polyvinyl alcohol, and the dispersant A accounts for 1% of the mass of the mixed powder, and the others are the same as in Example 1.

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Abstract

The invention provides a low-shrinkage porous silicon nitride ceramic and a preparation method thereof. Alpha-silicon nitride, alumina and yttria serve as main raw materials, and water-based ceramic slurry is prepared. The preparation method comprises the following steps: emulsifying in an oil phase to form spherical droplets, and performing freezing, oil-ceramic microsphere separation and freezedrying so as to obtain a porous ceramic microsphere body; sintering to obtain porous silicon nitride ceramic microspheres, performing size grading matching, performing mold shaping, curing, drying andsintering, finally obtaining the porous silicon nitride ceramic. Compared with the prior art, the low-shrinkage porous silicon nitride ceramic disclosed by the invention has the beneficial effects that dropping liquid in oil is combined with freeze molding to prepare the porous silicon nitride microspheres with different particle sizes, and the controllability of pore structures and porosity is realized by utilizing the freeze molding process; the low-shrinkage porous silicon nitride ceramic can be used for preparing a large porous silicon nitride special shaped component, and directivity ofthe pore structure caused in the freeze molding process is eliminated; moreover, the possibility that structure defects are caused by extremely great shrinkage in the sintering process is greatly reduced.

Description

technical field [0001] The invention relates to the technical field of forming porous ceramic materials, in particular to a low-shrinkage porous silicon nitride ceramic and a preparation method thereof. Background technique [0002] Porous silicon nitride ceramic material has excellent comprehensive properties such as high specific strength, high temperature resistance, oxidation resistance, wear resistance and thermal shock resistance, and also has relatively low density, low dielectric constant and dielectric loss And other excellent dielectric properties, because it can give full play to the excellent performance of both silicon nitride ceramics and porous ceramics, it is widely used in important fields such as machinery, chemical industry, marine engineering, aerospace and so on. [0003] Preparation of silicon nitride-based porous ceramics with controllable porosity and pore structure, high strength and low dielectric constant is the key to realize the application of si...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B38/00C04B35/584C04B35/622C04B35/64
CPCC04B35/584C04B35/622C04B35/64C04B38/00C04B2235/3217C04B2235/3225C04B2235/6562C04B2235/6567C04B2235/661C04B38/0074
Inventor 叶枫侯赵平张标叶健刘强高晔
Owner HARBIN INST OF TECH
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