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Preparation method of silicon nitride porous ceramic

A technology of porous ceramics and silicon nitride, which is applied in the field of preparation of silicon nitride porous ceramics, can solve the problems of unfavorable shape components, increase production costs, and difficulty in further increasing the porosity of ceramics, and achieve stable dielectric constant and improve mechanical strength. , high-strength effect

Inactive Publication Date: 2017-08-18
ANHUI TUOJITAI NOVEL CERAMIC TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantage is that the carbothermal reduction method requires a small amount of silicon nitride as a seed crystal, which increases the production cost to a certain extent. Due to the 44% weight loss in the reaction, the product has a large shrinkage during the sintering process, which is very demanding for the production shape components. unfavorable
[0007] However, the Si prepared by the currently disclosed technology 3 N 4 It is difficult to further improve the porosity of ceramics

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] A preparation method of silicon nitride porous ceramics, comprising the following steps:

[0025] 1) Calculated by weight percentage, weigh 85% of silicon nitride powder with a particle size of 0.1-10 μm, 10% of sintering aid and YbF 3 5%, mixed evenly to obtain a mixture;

[0026] 2) Add the mixture in step 1) to a polyvinyl alcohol solution with a mass concentration of 8%, and use zirconia ceramic balls for ball milling. The ball-to-material ratio is 4:1, and the ball milling time is 20 hours. The slurry is dried and sieved , and then molded into a blank;

[0027] 3) Rapidly raise the temperature of the blank to 1100°C in a nitrogen atmosphere, then slowly raise the temperature to 1500°C, and then raise the temperature to 1780°C at a heating rate of 0.6°C / min, keep it warm for 6 hours, and flow nitrogen throughout the sintering process. Finally, it is cooled with the furnace to obtain silicon nitride porous ceramics;

[0028] Wherein, the sintering aid is composed ...

Embodiment 2

[0031] A preparation method of silicon nitride porous ceramics, comprising the following steps:

[0032] 1) Calculated according to weight percentage, weigh 80% of silicon nitride powder, 18% of sintering aid and LaF 3 2%, mixed evenly to obtain a mixture;

[0033] 2) Add the mixture of step 1) into a polyvinyl alcohol solution with a mass concentration of 0.5%, and use alumina ceramic balls for ball milling. The ball-to-material ratio is 2:1, and the ball milling time is 24 hours. The slurry is dried and passed sieve, then compression molded into blanks;

[0034] 3) Rapidly raise the temperature of the blank to 1100°C in a nitrogen atmosphere, then slowly raise the temperature to 1500°C, then raise the temperature to 1700°C at a heating rate of 0.6°C / min, keep it warm for 3 hours, and flow nitrogen throughout the sintering process. Finally, it is cooled with the furnace to obtain silicon nitride porous ceramics;

[0035] Wherein, the sintering aid is composed of 10% magnes...

Embodiment 3

[0038] A preparation method of silicon nitride porous ceramics, comprising the following steps:

[0039] 1) Calculated by weight percentage, weigh 95% of silicon nitride powder with a particle size of 0.1-10 μm, 3% of sintering aid and CeF 3 2%, mixed evenly to obtain a mixture;

[0040] 2) Add the mixed material in step 1) into a polyvinyl alcohol solution with a mass concentration of 10%, perform ball milling with silicon nitride ceramic balls for 24 hours, dry the slurry, sieve it, and then mold it into a blank ;

[0041] 3) Rapidly raise the temperature of the blank to 1100°C in a nitrogen atmosphere, then slowly raise the temperature to 1500°C, and then raise the temperature to 1850°C at a heating rate of 0.6°C / min, keep it warm for 10 hours, and flow nitrogen throughout the sintering process. Finally, it is cooled with the furnace to obtain silicon nitride porous ceramics;

[0042] Wherein, the sintering aid is composed of 18% magnesium oxide, 20% silicon dioxide and ...

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Abstract

The invention provides a preparation method of a silicon nitride porous ceramic. The preparation method comprises the following steps of: 1) weighing 40-95wt% of silicon nitride powder, 1-20wt% of a sintering aid and 2-6wt% of a rare earth fluoride, and uniformly mixing the components to obtain a mixed material; 2) adding the mixed material obtain in the step 1) into a polyvinyl alcohol solution, the mass concentration of which is 0.5-10%, performing ball milling for 2-24h, drying and sieving slurry, and performing compression molding to obtain a blank; and 3) quickly raising the temperature of the blank in a nitrogen atmosphere to 1100 DEG C, then slowly raising the temperature to 1500 DEG C, then raising the temperature to 1700-1850 DEG C at a temperature raising rate of 0.6 DEG C / min, keeping the temperature for 1-10h, always introducing flowing nitrogen in a sintering process, and finally performing furnace cooling to obtain the silicon nitride porous ceramic, wherein the sintering aid is composed of magnesium oxide, silicon dioxide and barium carbonate. The silicon nitride porous ceramic prepared by the preparation method is high in porosity and high in bending strength.

Description

technical field [0001] The invention belongs to the technical field of ceramic preparation, and in particular relates to a preparation method of silicon nitride porous 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] According to the different starting powders used, the existing preparation methods of silicon nitride porous ceramic materials are as follows: [0004] Porous Si prepared by non-full-dense sintering method 3 N 4 Ceramics are usually α...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/584C04B35/64C04B38/00
Inventor 张天舒宋晓超何东张天宇
Owner ANHUI TUOJITAI NOVEL CERAMIC TECH