A kind of preparation method of porous silicon nitride ceramics with low metal ion residue

A technology of silicon nitride ceramics and metal ions, which is applied in the field of preparation of porous silicon nitride ceramics, can solve the problems of high temperature performance and dielectric performance decline of porous Si ceramics, and achieves the advantages of being beneficial to industrial production, simple and easy to implement, and helpful for industrialized production. The effect of dose reduction

Inactive Publication Date: 2015-11-25
XI AN JIAOTONG UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0008] In order to solve the problems in the above-mentioned prior art, the purpose of the present invention is to provide a method for preparing porous silicon nitride ceramics with low metal ion residues, which can realize low glass phase and low metal ion residues through a simple process, and solve the problems in the prior art. When preparing porous silicon nitride ceramic materials, due to the addition of a large amount of metal oxide sintering aids but cannot be removed, the porous Si 3 N 4 Ceramic high-temperature performance and dielectric performance decline and other problems; by adding a very small amount of sintering aids, high-strength porous Si can be obtained 3 N 4 Ceramics, at the same time, the metal ions in the sintering aid will be volatilized and removed during the sintering process, reducing the residue of metal ions in the grain boundary and improving the porous Si 3 N 4 High temperature performance and electrical properties

Method used

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  • A kind of preparation method of porous silicon nitride ceramics with low metal ion residue
  • A kind of preparation method of porous silicon nitride ceramics with low metal ion residue
  • A kind of preparation method of porous silicon nitride ceramics with low metal ion residue

Examples

Experimental program
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Effect test

Embodiment 1

[0036] The process steps are as follows:

[0037] (1) The raw material is Si with an average particle size of 0.5 microns 3 N 4 Powder 100g, Li 2 CO 3 1.63 grams of powder (equivalent to adding 0.66 grams of Li 2 O), Y 2 o 3 Powder 0.33 gram, with absolute ethanol as mixing medium, with agate ball as grinding ball, ball mill mixing 20 hours;

[0038] (2) Dry the mixed powder and pass through a 100-mesh sieve, and mold it under a pressure of 10MPa;

[0039] (3) The formed body is sintered at 1600°C in a nitrogen atmosphere of 0.2MPa and held for 4 hours, then vacuumed to less than 1 atmosphere (relative vacuum is -0.02MPa), and then heated to 1800°C and held for 4 hours. Hour.

[0040] Porous Si prepared by this method 3 N 4 The X-ray diffraction pattern of ceramics is attached figure 1 , the tested material is complete β-Si 3 N 4 . The porosity measured by the Archimedes method is 54.4%. The Li content measured by inductively coupled plasma atomic emission spect...

Embodiment 2

[0042] The difference from Example 1 is that the removal of the volatile liquid phase and metal ions is accomplished by vacuum heat treatment.

[0043] The process steps are as follows:

[0044] (1) The raw material is Si with an average particle size of 0.5 microns 3 N 4 Powder 100g, Li 2 CO 3 1.63 grams of powder (equivalent to adding 0.66 grams of Li 2 O), Y 2 o 3 Powder 0.33 gram, with absolute ethanol as mixing medium, with agate ball as grinding ball, ball mill mixing 20 hours;

[0045] (2) Dry the mixed powder and pass through a 100-mesh sieve, and mold it under a pressure of 10MPa;

[0046] (3) The formed body is sintered at 1600°C in a nitrogen atmosphere of 0.2MPa and kept for 4 hours.

[0047] (4) Porous Si after sintering 3 N 4 The samples were heat-treated at 1500°C for 6 hours under vacuum conditions.

[0048] Porous Si prepared by this method 3 N 4 The ceramics are shown by X-ray diffraction patterns to be complete β-Si 3 N 4 . The porosity measu...

Embodiment 3

[0050] The difference from Example 1 is that only Li 2 O as a sintering aid.

[0051] The process steps are as follows:

[0052] (1) The raw material is Si with an average particle size of 0.5 microns 3 N 4 Powder 100g, Li 2 CO 3 2.47 grams of powder (equivalent to adding 1 gram of Li 2 O), using absolute ethanol as the mixing medium, using agate balls as the grinding balls, and ball milling and mixing for 20 hours;

[0053] (2) Dry the mixed powder and pass through a 100-mesh sieve, and mold it under a pressure of 10MPa;

[0054] (3) The formed body is sintered at 1600°C in a nitrogen atmosphere of 0.2MPa and held for 4 hours, then vacuumed to less than 1 atmosphere (relative vacuum is -0.02MPa), and then heated to 1800°C and held for 4 hours. Hour.

[0055] Porous Si prepared by this method 3 N 4 The X-ray diffraction pattern of ceramics shows that the tested material is complete β-Si 3 N 4 . The porosity measured by the Archimedes method is 56.1%. The Li conte...

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Abstract

The invention discloses a preparation method of porous silicon nitride ceramic with residues of low metal ions, which solves the problem that when the porous silicon nitride ceramic is prepared by liquid phase sintering, due to addition of mass sintering aid, mass glass phase and metal ions are remained in a crystal boundary so that the high temperature performance and electrical property of material are decreased. The method comprises the following steps: employing silicon nitride powder as a raw material, taking metal oxide Li2O with high temperature and strong volatility and a few of cooperated rare earth oxide as a sintering aid, performing pressureless sintering under nitrogen atmosphere, wherein the sintering temperature is 1600 DEG C, using high temperature to volatilize Li ions and Li-containing liquid phase, and removing Li ions and Li-containing liquid phase in vacuum heat treatment at 1500 DEG C or high temperature heat treatment at 1800 DEG C. The porosity of the porous silicon nitride ceramic is between 50%-60%, the bending strength is 65-150MPa, wherein Li content is lower than 0.03%, and the rare earth ion content is lower than 0.3%.

Description

technical field [0001] The invention relates to the preparation technology of porous silicon nitride ceramics, and in particular provides a preparation method of porous silicon nitride ceramics with low residual metal ions. Background technique [0002] Porous silicon nitride ceramics retains the advantages of dense silicon nitride ceramics, with excellent room temperature and high temperature strength, excellent thermal shock resistance and chemical corrosion resistance. At the same time, porous silicon nitride ceramics are more dense than dense silicon nitride ceramics. Lightweight and has a lower dielectric constant; due to the rod-shaped structure of porous silicon nitride ceramics, it has higher strength and toughness under high porosity conditions than other porous oxide ceramics. Therefore, porous silicon nitride ceramics is a promising high-temperature structure-functional integration material, which is widely used in important fields such as machinery, chemical indu...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B35/584C04B35/622C04B38/00
Inventor 王红洁樊磊史忠旗王继平夏鸿雁
Owner XI AN JIAOTONG UNIV
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