Preparation method of porous silicon nitride ceramic

A technology of silicon nitride ceramics and silicon nitride powder, which is applied in ceramic products, applications, household appliances, etc., can solve problems such as unfavorable sintering, and achieve the effects of shortening production cycle, simple process and saving production cost.

Inactive Publication Date: 2019-05-10
TECHNICAL INST OF PHYSICS & CHEMISTRY - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
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  • Application Information

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Problems solved by technology

In summary, how to balance strength and porosity, and prepare porous silicon nitride ceramics in a low-cost, short-cycle manner is still a challenge
In addition, the particle size of ceramic powder raw materials generally used for sintering is mostly sub-micron, and the direct use of micron-sized or even tens of micron-sized powder raw materials is not conducive to sintering.

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  • Preparation method of porous silicon nitride ceramic
  • Preparation method of porous silicon nitride ceramic
  • Preparation method of porous silicon nitride ceramic

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preparation example Construction

[0039] Specifically, the present invention proposes a method for preparing porous silicon nitride ceramics, comprising the following steps:

[0040] The silicon powder, the silicon nitride powder and the sintering aid powder are uniformly mixed to obtain a mixed powder, and the mixed powder is formed into a green body, and the green body is induced to undergo nitriding and sintering reaction under a nitrogen atmosphere to obtain a porous silicon nitride ceramic. The preparation method of the invention utilizes the combustion nitriding technology of silicon powder, has low energy consumption, simple process, self-purification function and short production cycle.

[0041] As a preferred embodiment, in terms of mass percentage, the mixed powder includes: 30-70 wt% of silicon powder, 29-65 wt% of silicon nitride powder, and 1-15 wt% of sintering aid powder. The preparation method of the present invention does not use any volatile and harmful substances in the whole synthesis proce...

Embodiment 1

[0052] A kind of preparation of porous silicon nitride ceramics, comprises the steps:

[0053] 1) Raw material ratio: take 42.5 g of silicon powder with a particle size of 8 μm, 42.5 g of silicon nitride powder with a particle size of 10 μm and an α-phase content of 90 wt%, and 15 g of yttrium oxide powder;

[0054] 2) Preparation of porous ceramic body: mix silicon powder, silicon nitride powder and yttrium oxide powder uniformly according to the proportion of step 1) to obtain a mixed powder, and mold the mixed powder into a green body, the obtained green body The porosity is 65%;

[0055] 3) Combustion reaction: put the green body obtained in step 2) into the nitriding reaction kettle, fill it with 5MPa high-purity nitrogen (purity>99.999vol%), and then initiate the nitriding sintering reaction by partial ignition ;

[0056] 4) Obtaining of porous ceramics: After the mixed powder has reacted completely, lower the temperature to room temperature, release the gas in the rea...

Embodiment 2

[0060] A kind of preparation of porous silicon nitride ceramics, comprises the steps:

[0061] 1) Raw material ratio: 30 g of silicon powder with a particle size of 0.1 μm, 65 g of silicon nitride powder with a particle size of 10 μm and an α-phase content of 100 wt%, and 5 g of yttrium oxide powder;

[0062] 2) Preparation of porous ceramic body: mix silicon powder, silicon nitride powder and yttrium oxide powder uniformly according to the proportion of step 1) to obtain a mixed powder, and mold the mixed powder into a green body, the obtained green body The porosity is 45%;

[0063] 3) Combustion reaction: put the green body prepared in step 2) into the nitriding reaction kettle, fill it with 10MPa high-purity nitrogen (purity>99.999vol%), and then initiate nitriding sintering synthesis by partial ignition reaction;

[0064] 4) Obtaining of porous ceramics: After the mixed powder has reacted completely, lower the temperature to room temperature, release the gas in the reac...

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Abstract

The invention discloses a preparation method of porous silicon nitride ceramic, comprising the steps of mixing silicon powder, silicon nitride powder and sintering aid powder to obtain mixed powder, shaping the mixed powder to obtain a blank, and inducing the blank to experience nitridizing sintering reaction under nitrogen atmosphere to obtain the porous silicon nitride ceramic. The preparation of the porous silicon nitride ceramic with coarse powdery materials is provided herein for the first time; the core is to cause complete dissolution-separation phase change to coarse alpha-Si3N4 underhigh temperature and liquid phase conditions generated by combustive synthesis, so that beta-Si3N4 ceramic is generated. The preparation method herein which employs a self-propagating combustive synthesis technique is low in energy consumption; the process is simple; the ceramic herein has a self-purifying function, and the production cycle is short.

Description

technical field [0001] The invention relates to the technical field of porous silicon nitride ceramics. More specifically, it relates to a preparation method of porous silicon nitride ceramics. Background technique [0002] Silicon nitride has excellent mechanical, thermal, and dielectric properties, as well as thermal and chemical stability. These inherent characteristics make porous silicon nitride materials also have outstanding advantages, and are often used as high-temperature gas filter materials, catalyst carriers, radome and diaphragm materials, etc. Despite the above excellent properties, the large market for porous silicon nitride ceramics has not been opened for a long time, and the progress of preparation methods may change this situation. [0003] At present, many methods for preparing porous silicon nitride ceramics have been developed, such as gel casting method, freeze-drying method, adding pore-forming agents, reducing the content of sintering aids, and re...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/591C04B35/596C04B35/622C04B38/00
Inventor 贺刚王良吴晓明杨增朝李江涛
Owner TECHNICAL INST OF PHYSICS & CHEMISTRY - CHINESE ACAD OF SCI
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