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Method for combustion synthesis of silicon nitride powder by using polytetrafluoroethylene as additive

A polytetrafluoroethylene, combustion synthesis technology, applied in the direction of chemical instruments and methods, nitrogen compounds, inorganic chemistry, etc., can solve the problems of unsuitable industrial production, low net yield, increased cost, etc., to avoid the process of process, The effect of low production cost and easy operation

Inactive Publication Date: 2008-07-30
TECHNICAL INST OF PHYSICS & CHEMISTRY - CHINESE ACAD OF SCI +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The main problem with this approach is that it makes the net yield of the product low, resulting in high cost
Obviously, these processes will increase the cost for the preparation of silicon nitride powder with an α-phase content of 60-80%, and are not suitable for industrial production

Method used

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  • Method for combustion synthesis of silicon nitride powder by using polytetrafluoroethylene as additive
  • Method for combustion synthesis of silicon nitride powder by using polytetrafluoroethylene as additive

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] Weigh the raw materials according to the weight ratio of silicon powder (purity > 99%, particle size range 0.1-10 μm): ammonium chloride: PTFE 90:9:1, put the prepared raw materials on a vibrating grinder, mix and grind for 1 hour , After grinding, the powder is sieved, and then put into a porous graphite crucible, the bulk density is 0.8~2.0g / cm 3 . Put the powdered porous graphite crucible into a 40L combustion synthesis reaction device, and place a spiral tungsten wire and titanium powder at one end of the powder blank as an ignition source. After vacuuming, fill the combustion synthesis reaction device with nitrogen until the pressure reaches 1.5 MPa. The tungsten wire is energized and heated to ignite the titanium powder, inducing the combustion synthesis reaction of the powder system. Combustion synthesized products with furnace cooling. The obtained product is subjected to post-treatment processes such as pulverization and fine grinding to obtain a homogeneous...

Embodiment 2

[0034] Take the raw material according to the weight ratio of silicon powder (purity > 99%, particle size range is 0.1 ~ 10 μ m): ammonium salt: PTFE is 73: 22: 5, wherein the ammonium salt is the mixture of ammonium chloride and ammonium fluoride, The ratio of parts by weight is 1:1. Put the prepared raw materials on a vibrating grinder and mix and grind for 1 hour. After grinding, the powder is sieved and then put into a porous graphite crucible. The bulk density is 0.8-2.0g / cm 3 . Put the powdered porous graphite crucible into a 40L combustion synthesis reaction device, and place a spiral tungsten wire and titanium powder at one end of the powder blank as an ignition source. After vacuuming, a mixture of nitrogen and argon is charged into the combustion synthesis reaction device, wherein the proportion of argon is 20 vol%, until the pressure reaches 3 MPa. The tungsten wire is energized and heated to ignite the titanium powder, and (by local heating) induces the combustio...

Embodiment 3

[0036] According to silicon powder (purity > 99%, particle diameter range is 0.1~10 μ m): (ammonium salt+nitrogen-containing compound): PTFE is the weight ratio of 81: 10: 9 and takes raw material, wherein ammonium salt is ammonium chloride and Ammonium carbonate, the nitrogen-containing compound is urea, and its weight ratio is 1:1:1. Put the prepared raw materials on a vibrating grinder and mix and grind for 1 hour. After grinding, the powder is sieved and then put into a porous graphite crucible. The bulk density is 0.8-2.0g / cm 3 . Put the powdered porous graphite crucible into a 40L combustion synthesis reaction device, and place a spiral tungsten wire and titanium powder at one end of the powder blank as an ignition source. After vacuuming, a mixture of nitrogen and hydrogen is charged into the combustion synthesis reaction device, wherein the proportion of hydrogen is 25 vol%, until the pressure reaches 4.5 MPa. The tungsten wire is energized and heated to ignite the t...

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Abstract

The invention belong s to the preparation technical filed of silicon nitride ultrafine powder of non-oxide, in particular relating to a method in which when non-silicon nitride is taken as diluents, polytetrafluoroethylene is taken as addictive to combust and synthesize silicon nitride powder. Silicon powder, ammonium salt or nitrogen compound and polytetrafluoroethylene are taken as the raw material, the reaction mixture is prepared according to different component ratio; the mixture after ground and mixed for a while is put into an airtight vessel of high temperature resistance with apparent density of 0.8-2.0g / cm<3>; nitrogen and ammonia and so on are filled into the device after a reaction device is vacuumized. The gas pressure of the reaction device for combusting and synthesizing is controlled within 5MPa; products are processed by fine grinding to obtain the homogenous silicon nitride powder and the content of Alpha phase is 60 to 80 percent. The invention realizes that the silicon power is combusted and synthesized to be the silicon nitride under the condition that non-silicon nitride is taken as diluents and break through the limitation that the traditional combusting and synthesizing process of the silicon nitride must be added with a large amount of silicon nitride diluents. The method of the invention improves the net yield and reduces the cost.

Description

technical field [0001] The invention belongs to the technical field of preparation of non-oxide ultrafine silicon nitride powder, and relates to a method for combustion synthesis (also known as self-propagating high-temperature synthesis) of silicon nitride powder, in particular to the use of polytetrafluoroethylene when there is no silicon nitride diluent. Combustion of vinyl fluoride (PTFE) as an additive to synthesize silicon nitride (Si 3 N 4 ) powder method. Background technique [0002] As an important high-temperature structural ceramic material, silicon nitride ceramics have low density, low specific gravity, high hardness, corrosion resistance, wear resistance, high temperature resistance, high elastic modulus, oxidation resistance, thermal shock resistance and electrical insulation properties Good and other advantages, it has been widely used in bearings, rolls, cutting tools, engine parts, etc., and has great development potential. Silicon nitride powder is use...

Claims

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Application Information

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IPC IPC(8): C01B21/068C04B35/584
Inventor 李江涛陈义祥林志明杨树亮杜吉胜王建力
Owner TECHNICAL INST OF PHYSICS & CHEMISTRY - CHINESE ACAD OF SCI
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