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Technique for preparing silicon nitride powders with high alpha phase by using plasma chemical vapor phase process

A phase silicon nitride powder, plasma technology, applied in chemical instruments and methods, inorganic chemistry, nitrogen compounds, etc., can solve the problems of high C content in the product, doping, complicated process control, etc., to achieve uniform particle size distribution, high The effect of high α-phase content and high purity

Inactive Publication Date: 2003-10-01
白万杰
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

At present, the commonly used silicon nitride powder preparation methods include (1) direct silicon powder nitriding method, which is simple and low in cost, because the reaction between silicon and nitrogen is an exothermic reaction, in order to make the silicon powder fully react, the process control is relatively Complex; at the same time, due to the purity of the raw material itself and the doping of the grinding process after nitriding, the purity of the powder is not high
(2) Carbothermal reduction of silica method, this method uses silica which is very abundant in nature as a raw material, coupled with a faster reaction rate, it is especially suitable for large-scale production, but the disadvantage is that the C content in the product is relatively high

Method used

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  • Technique for preparing silicon nitride powders with high alpha phase by using plasma chemical vapor phase process
  • Technique for preparing silicon nitride powders with high alpha phase by using plasma chemical vapor phase process

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] First, the plasma working gas N is introduced into the plasma generator 2 -H 2 -Ar, press N 2 9m 3 / h; H 2 27m 3 / h; The flow rate is continuously injected, and 30 liters / min of Ar is injected, the plasma power supply is started, and a plasma arc is generated in the plasma generator, (the Ar gas is turned off after the arc starts normally). The gas after the arc is heated to a high temperature of 4800°C and enters the reactor to decompose rapidly, keeping SiCl 4 and NH 3 The ratio is 1:8 (injection liquid weight ratio per unit time) for continuous injection, and the reaction temperature in the plasma reactor is kept at 1250°C. Si 3 N 4 Rapid decomposition in a plasma reactor and generation of solid Si using free-settling and quenching conditions 3 N 4 micronized powder,

[0022] Generated Si 3 N 4 After crystallization and growth in a very short time (millisecond level), after cooling, the gas-solid separation is achieved through the bag powder collec...

Embodiment 2

[0027] First, the plasma working gas N is introduced into the plasma generator 2 -H 2 -Ar, press N 2 13m 3 / h; H 2 32m 3 / h; The flow rate is continuously injected, and 30 liters / min of Ar is injected, the plasma power supply is started, and a plasma arc is generated in the plasma generator, (the Ar gas is turned off after the arc starts normally). After the arc gas is heated to a high temperature of 5200°C, it enters the reactor and decomposes rapidly, keeping SiCl 4 and NH 3 The ratio is 1:5 (injection liquid weight ratio per unit time) for continuous injection, and the reaction temperature in the plasma reactor is kept at 1100°C. Rapid decomposition in a plasma reactor and generation of solid Si using free-settling and quenching conditions 3 N 4 micronized powder,

[0028] Generated Si 3 N 4 After crystallization and growth in a very short time (millisecond level), after cooling, the gas-solid separation is achieved through the bag powder collector to obtai...

Embodiment 3

[0032] First, the plasma working gas N is introduced into the plasma generator 2 -H 2 -Ar, press N 2 11m 3 / h; H 2 30m 3 / h; The flow rate is continuously injected, and 30 liters / min of Ar is injected, the plasma power supply is started, and a plasma arc is generated in the plasma generator, (the Ar gas is turned off after the arc starts normally). The gas after the arc is heated to a high temperature of 5000°C and enters the reactor to decompose rapidly, keeping SiCl 4 and NH 3 The ratio is 1:10 (injection liquid weight ratio per unit time) for continuous injection, and the reaction temperature in the plasma reactor is kept at 1400°C. Rapid decomposition in a plasma reactor and generation of solid Si using free-settling and quenching conditions 3 N 4 micronized powder,

[0033] Generated Si 3 N 4 After crystallization and growth in a very short time (millisecond level), after cooling, the gas-solid separation is achieved through the bag powder collector to ob...

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Abstract

A process for preparing high-alpha-phase silicon nitride powder by plasma chemical gas phase method includes such steps as quickly heating the gas to high temp by the plasma of DC arc, evaporating while heating SiCl4 and NH3 gases, quick decomposing and synthesizing reactions to generate Si3N4, crystallizing, growing cooling, gas-solid separation by cloth-bag collector, removing NH4Cl and high-temp phase change. Its advantages are high purity, high content of alpha phase, and fine granularity (nano class).

Description

technical field [0001] The invention relates to a process for preparing silicon nitride powder by a plasma chemical vapor phase method. technical background [0002] Silicon nitride ceramics have a series of advantages such as high hardness, high strength, wear resistance, high temperature resistance, small thermal expansion coefficient, large thermal conductivity, good thermal shock resistance, and low density. They are used in ceramic engines, machining, microelectronics, Space science and nuclear power engineering and other fields have extremely broad application prospects. At present, the commonly used silicon nitride powder preparation methods include (1) direct silicon powder nitriding method, which is simple and low in cost, because the reaction between silicon and nitrogen is an exothermic reaction, in order to make the silicon powder fully react, the process control is relatively Complicated; at the same time, due to the purity of the raw material itself and the do...

Claims

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Application Information

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IPC IPC(8): C01B21/068C04B35/584C23C16/50
Inventor 白万杰
Owner 白万杰
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