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Method for preparing alpha phase and beta phase silicon nitride powder by improved direct nitriding method

A technology of phase silicon nitride powder and nitriding method, which is applied in the field of preparation of silicon nitride products, can solve the problems of high powder production cost, influence powder performance, complicated preparation process, etc., to save gas consumption and improve penetration. The effect of pressure, simple operation process

Inactive Publication Date: 2013-10-02
SHANGHAI UNIV
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  • Description
  • Claims
  • Application Information

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Problems solved by technology

Although the particle size of the silicon nitride powder synthesized by this method is uniform, and the content of α-Si3N4 is relatively high, the actual amount of C is often excessive, resulting in The residual amount of C is relatively high, and when the reaction temperature is not uniform, SiC, Si2N2O and other phases are often formed in the product, which affects the powder properties
[0006] Gas-phase method and liquid-phase method can also prepare high-purity, high-α-phase silicon nitride powder, but due to the large number of raw materials and relatively high prices in the preparation process, The preparation process is relatively complicated, resulting in high powder production costs and not conducive to large-scale industrial production

Method used

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  • Method for preparing alpha phase and beta phase silicon nitride powder by improved direct nitriding method

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Experimental program
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Effect test

Embodiment 1

[0024] The present invention adopts the traditional commonly used such as figure 1 The experimental device used an improved direct nitriding method to prepare α-phase and β-phase silicon nitride powders, followed by the following steps:

[0025] (1) After crushing the metal silicon block, ball mill and sieve to control the particle size of silicon powder to ≤500μm;

[0026] (2) Loosely pack metal silicon powder into a rectangular corundum crucible, put the crucible and the powder into a tube-type test furnace, and evacuate to (1.0~2.0)×10 -2 Pa, filled with protective gas argon, the pressure is 0.1~0.15MPa;

[0027] (3) Turn on the power and heat at a rate of 3°C / min. After the temperature rises to 1500°C, vacuumize to (1.0~2.0)×10 -2 Pa, adjust the volume ratio of nitrogen and argon to 1:1 through gas flow meters (1) and (2), open the valve, mix evenly and fill into the furnace chamber, the total pressure is about 0.1MPa, and the reaction time is 6h.

[0028] (4) Turn off...

Embodiment 2

[0030] The present invention adopts the traditional commonly used such as figure 1 The experimental device used an improved direct nitriding method to prepare α-phase and β-phase silicon nitride powders, followed by the following steps:

[0031] (1) Ball mill and sieve metal silicon powder to control the particle size of silicon powder to ≤150μm;

[0032](2) Loosely pack the silicon powder into a rectangular corundum crucible, put the crucible and the powder into the tubular test furnace, and evacuate to (1.0~2.0)×10 -2 Pa, filled with protective gas argon, the pressure is 0.1~0.15MPa;

[0033] (3) Turn on the power and heat at a rate of 3°C / min. After the temperature rises to 1400°C, vacuumize to (1.0~2.0)×10 -2 Pa, adjust the volume ratio of nitrogen and argon to 1:2 through gas flow meters (1) and (2), open the valve, mix evenly and fill into the furnace chamber, the total pressure is about 0.1MPa, and the reaction time is 5h.

[0034] (4) Turn off the power, cool down ...

Embodiment 3

[0036] The present invention adopts the traditional commonly used such as figure 1 The experimental device used an improved direct nitriding method to prepare α-phase and β-phase silicon nitride powders, followed by the following steps:

[0037] (1) Ball mill and sieve metal silicon powder to control the particle size of silicon powder to ≤74μm;

[0038] (2) Loosely pack metal silicon powder into a rectangular corundum crucible, put the crucible and the powder into a tube-type test furnace, and evacuate to (1.0~2.0)×10 -2 Pa, filled with protective gas argon, the pressure is 0.1~0.15MPa;

[0039] (3) Turn on the power supply and heat at a heating rate of 3°C / min. After the temperature rises to 1300°C, vacuumize to (1.0~2.0)×10 -2 Pa, adjust the volume ratio of nitrogen and argon to 1:3 through gas flow meters (1) and (2), open the valve, mix evenly and fill into the furnace chamber, the total pressure is about 0.1MPa, and the reaction time is 4h.

[0040] (4) Turn off the ...

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Abstract

The invention relates to a method for preparing alpha phase and beta phase silicon nitride powder by improved direct nitriding method. The method is mainly an improvement based on the existing direct nitriding method; metallic silicon powder and nitrogen react in a completely sealed reaction device; reaction gas is mixed gas of the nitrogen and inert gas (such as argon); and the inert gas has two functions of serving as shielding gas to prevent the silicon powder from oxidation and performing supercharging to raise seepage pressure of the nitrogen to promote nitriding of metallic silicon during reaction. The reaction speed of the metallic silicon and the nitrogen is controlled by adjusting the proportion of the nitrogen in the mixed gas to control the temperature in a reaction vessel, and a silicon nitride product with an objective constituent phase (an alpha phase and a beta phase) can be obtained finally. The method is simple in operation process, reduces energy and raw material consumption, does not require an additional diluent, a catalyst and the like, greatly saves production cost, and facilitates realizing industrial production.

Description

technical field [0001] The invention belongs to the field of inorganic non-metallic materials, and relates to a method for preparing silicon nitride products, in particular to a method for controlling the reaction speed of metal silicon and nitrogen by adjusting the ratio and flow rate of nitrogen and inert gas (such as argon), and then Realize the method of controlling the temperature in the reaction vessel, and finally obtain the silicon nitride product of the target composition phase (α phase and β phase). Background technique [0002] With the rapid development of modern advanced technology, especially the continuous breakthroughs in aerospace, nuclear reactors, new energy development and other fields, a working environment with higher temperature, higher speed and stronger corrosion has emerged. More stringent requirements, some traditional metal-based superalloys can no longer meet people's needs, but high-temperature structural ceramic materials with excellent mechani...

Claims

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Application Information

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IPC IPC(8): C01B21/068
Inventor 余仲达王磊张捷宇王赫刘国奇王刚
Owner SHANGHAI UNIV
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