KR100972601B1 - Process for producing nano-sized silicon carbide powder - Google Patents

Abstract

The present invention relates to a method for producing silicon carbide nanopowder, and more specifically, a first step of preparing a uniform mixed solution by dissolving a polysiloxane powder and a carbon source in an organic solvent; A second step of drying the prepared liquid mixture; A third step of curing the polysiloxane in the dried mixture; A fourth step of pyrolyzing the mixture cured polysiloxane; And a fifth step of thermally decomposing the pyrolyzed mixture, wherein the silicon carbide nanopowder is prepared. The reactivity is dramatically reduced by preparing a molecularly uniform mixture using a silicon source and a carbon source as a raw material dissolved in a liquid phase. It is possible to produce fine silicon carbide nanopowders with an average particle diameter of 80 nm or less at relatively low temperatures of 1600 ° C or less, and to use impurities in the process by using organic materials consisting of Si, H, O and C only as silicon sources and carbon sources. It is possible to prepare a high purity silicon carbide nanopowder having a purity of 99.99% or more by excluding the possibility of entering the same.

Silicon Carbide, Average Particle Size, Nano, Powder, Polysiloxane, High Purity, Liquid Phase Reaction

Description

Manufacturing Method of Silicon Carbide Nanopowder {PROCESS FOR PRODUCING NANO-SIZED SILICON CARBIDE POWDER}

The present invention relates to a method for producing silicon carbide nanopowder having an average particle diameter of 10 to 80 nm and a purity of 99.99% or more.

Silicon carbide (SiC) is physically and chemically stable, has excellent heat resistance and high thermal conductivity, high temperature stability, high temperature strength, and high wear resistance. Therefore, high temperature materials, high temperature semiconductors, jig for semiconductors, wear resistant materials, It is mainly used to manufacture corrosion resistant or chemical resistant parts or electronic parts of automobile parts, chemical plants. In particular, in the case of nano-sized silicon carbide powder, the surface energy is high, and thus, the sintering property is excellent, so that a dense silicon carbide product can be manufactured even at low temperature, and has the advantage of being widely used as a reinforcing material for various nanocomposites. As a specific example, Korean Patent No. 0624066 (registered on September 19, 2006) adds silicon carbide nanopowder as a reinforcing material to alumina (Al ₂ O ₃ ) to manufacture nano composite materials, which is useful for cutting tools due to its excellent wear resistance. U.S. Patent No. 5,591,685 (registered on Jan. 07, 1997) has a superplastic property when manufacturing silicon carbide nano ceramics using silicon carbide nano powder, which is used as a high temperature material having a complex shape. It is disclosed that.

Such silicon carbide powder is produced by the following four methods.

The first method is a solid-state reaction, widely known as the Acheson process, in which a solid carbonaceous material (carbon black, graphite, etc.) is mixed with a solid silicon material (mainly silica (SiO ₂ )). It is a method for preparing silicon carbide powder by a carbon thermal reduction reaction as shown in Scheme 1 below.

SiO ₂ + 3C → SiC + 2CO ↑

The silicon carbide powder prepared by the above method is coarse with an average particle diameter of 1 to 100 mm, thereby pulverizing the silicon carbide powder having an average particle diameter of 100 to 1000 nm. However, it is cumbersome to perform a further grinding process, and it is difficult to produce finer silicon carbide nanopowders with an average particle diameter of 80 nm or less even when grinding.

The second method is a solid-liquid reaction method as disclosed in US Pat. No. 6,730,283 (registered May 4, 2004). Solid-liquid phase reaction of US Pat. No. 4,730,283 impregnates solid graphite expanded graphite with liquid organosilicon compound, and calcinates at a temperature of 1300 ° C. or higher under an inert gas atmosphere to produce silicon carbide powder. That's how. The average particle diameter of the silicon carbide powder produced by this method is 100 to 1000 nm.

The third method is a gas phase reaction method as disclosed in US Patent No. 4,613,490 (registered on September 23, 1986) and Korean Patent No. 0318350 (registered on December 10, 2001). The gas phase reaction of US Pat. No. 4,613,490 is a method of preparing silicon carbide powder having an average particle diameter of 100 to 300 nm by heating an aminosilane compound, cyanosilane compound, or silazane compound in an inert atmosphere. to be. In addition, the gas phase reaction of Korean Patent No. 0318350 is a method of producing a silicon carbide powder having an average particle diameter of 0.001 to 10 ㎛ by heating the vaporized polysiloxane. However, such a gas phase reaction is expensive because it requires an additional device for heating and vaporizing the silicon source, the risk of the reaction temperature is higher than 1600 ℃ high temperature. In addition, when using polysiloxane, it is difficult to adjust the molar ratio of the silicon source and carbon source of the powder manufactured by decomposition | disassembly of polysiloxane to 1: 1 which is a stoichiometric molar ratio of silicon carbide.

The fourth method is a liquid phase reaction method as disclosed in US Pat. No. 6,627,169 (registered on September 30, 2003) and US Pat. No. 7,029,643 (registered on April 18, 2006). The liquid phase reaction of US Pat. No. 6,627,169 is a method for producing silicon carbide powder having an average particle diameter of 1 to 50 μm by reacting ethyl silicate, which is a liquid silicon source, and a resol type phenol resin, which is a liquid carbon source. In addition, U.S. Patent No. 7,029,643 has a nitrogen content of 50 ppm or less, an impurity content of 0.3 ppm or less, and an average of alkoxysilane, a silicon raw material, and a resol type xylene-based resin. It is a method of manufacturing the silicon carbide powder whose particle diameter is 1-500 micrometers.

According to the production method as described above, it is difficult to produce fine silicon carbide powder of fine purity with an average particle diameter of 80 nm or less to be provided in the present invention. If the average particle diameter of the silicon carbide powder becomes nano size, especially 10 to 80 nm, the surface energy of the nano powder is increased to produce silicon carbide sintered body, silicon carbide single crystal growth, reinforcement material of nanocomposite material, semiconductor jig and crystal It can be used more effectively as a raw material such as silicon carbide nanoceramic having a particle size of 100 nm or less.

Therefore, the development of high purity silicon carbide nanopowder having an average particle diameter of 80 nm or less is required.

Accordingly, the inventors have intensively studied, and the silicon carbide polysiloxane (polysiloxane) and the carbon source at the same time dissolved in an organic solvent and uniformly mixed in the molecular form, and then dried, cured, pyrolyzed and carbon heat reduction through silicon carbide In the case of powder preparation, no additional device for vaporizing polysiloxanes as in the gas phase reaction was needed, and the molar ratio of carbon source and silicon source could be easily adjusted to 1: 1, the stoichiometric molar ratio of silicon carbide. In addition, the reactivity is dramatically improved by uniformly mixing the carbon source and the silicon source, and the average particle diameter is smaller than 80 nm and the purity is higher than 99.99% even at a relatively low temperature of 1600 ° C. or less and carbon heat reduction with a short reaction time. It was confirmed that the production of silicon carbide nanopowder was possible, and based on this, the present invention was completed.

Accordingly, an object of the present invention is to provide a method for producing silicon carbide nanopowders having an average particle diameter of 10 to 80 nm and a purity of 99.99% or more.

Another object of the present invention is to provide a silicon carbide nanopowder prepared by the method for producing the silicon carbide nanopowder.

The present invention provides a method for producing a silicon carbide nanopowder, the first step of preparing a uniform mixture by dissolving a polysiloxane powder and a carbon source in an organic solvent; A second step of drying the prepared liquid mixture; A third step of curing the polysiloxane in the dried mixture; A fourth step of pyrolyzing the mixture cured polysiloxane; And a fifth step of carbon thermally reducing the pyrolyzed mixture.

In addition, the present invention is prepared by a method for producing silicon carbide nanopowder comprising the first step to the fifth step to provide a silicon carbide nanopowder, characterized in that the average particle diameter is 10 to 80nm, purity is 99.99% or more. do.

According to the present invention, by using a silicon source and a carbon source as a raw material that is dissolved in a liquid phase to prepare a mixture of a silicon source and a carbon source in a molecular shape, the reactivity is dramatically improved, so that a relatively low reaction temperature and a short reaction time carbon heat Reduction also enables the production of silicon carbide nanopowders with a small average particle diameter of 80 nm or less. In addition, by using an organic material consisting of only Si, H, O and C as a silicon source and a carbon source, it is possible to prepare a high purity silicon carbide nanopowder having a purity of 99.99% or more by eliminating the possibility of impurities entering during the process. In addition, the high-purity silicon carbide nanopowder according to the present invention can be used as a raw material for the production of various silicon carbide sintered body, silicon carbide single crystal growth, reinforcing material of nanocomposites and jig for semiconductor, in particular, the crystal grain size is 100 nm or less It can be usefully used for the production of silicon carbide nanoceramic.

The present invention relates to a method for producing silicon carbide nanopowder having an average particle diameter of 10 to 80 nm and a purity of 99.99% or more.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

Method for producing a silicon carbide nanopowder of the present invention comprises the first step of producing a uniform mixture by dissolving the polysiloxane powder and carbon source in an organic solvent; A second step of drying the prepared liquid mixture; A third step of curing the polysiloxane in the dried mixture; A fourth step of pyrolyzing the mixture cured polysiloxane; And a fifth step of carbon thermally reducing the pyrolyzed mixture.

In the method for producing the silicon carbide nanopowder of the present invention, the first step is a step in which a polysiloxane powder, which is a silicon source, and a carbon source are dissolved in an organic solvent to prepare a molecularly uniform mixture.

In the conventional production of silicon carbide nanopowders, silica or a silane compound is used as the silicon source. First, in the case of using silica, since silica is not dissolved in an organic solvent, it is difficult to form a homogeneous mixture with a carbon source and thus requires a high reaction temperature exceeding 1600 ° C., and silicon carbide having an average particle diameter of 1 μm or more. Powder is prepared. In addition, when using a silane compound such as methyltrichlorosilane or dimethyldichlorosilane as a silicon source, special care is required for handling due to the corrosiveness and toxicity of the silane compound. The ratio of carbon source to silicon source is difficult to achieve in stoichiometric ratio, and generally contains an excess of free carbon. On the other hand, when polysiloxane is used, the molar ratio of silicon source and carbon source can be easily adjusted to 1: 1, which is the stoichiometric molar ratio of silicon carbide, by dissolving polysiloxane and carbon source simultaneously in an organic solvent without additional equipment, thereby improving reactivity. do. Therefore, it is preferable to use polysiloxane as the silicon source in the liquid phase reaction.

As the polysiloxane, all conventional polysiloxanes may be used, and the compound represented by the following Chemical Formula 1 or Chemical Formula 2 or a copolymer thereof may preferably use a weight average molecular weight of 150 to 5000, and the silicon carbide nano In consideration of the yield as well as the average particle diameter of the powder, it is more preferable to use the compound represented by the formula (1). In addition, when the weight average molecular weight of the polysiloxane is less than 150, the loss of the silicon source is large in the pyrolysis step, and when it exceeds 5000, the pyrolysis and reaction time are long and inefficient.

[RSiO _1.5 ] _n

In Formula 1, R is a hydrogen atom, a hydroxyl group or an alkyl group, n is a value determined by the weight average molecular weight of the polysiloxane is an integer.

[R ₂ SiO] _n

In Formula 2, R is each independently a hydrogen atom, an alkyl group, an alkenyl group or a cyclic group, n is a value determined by the weight average molecular weight of the polysiloxane.

The alkyl group is methyl, ethyl, propyl or butyl, the alkenyl group is vinyl, allyl or hexenyl and the cyclic group can be cyclopentyl, cyclohexane or cyclophenyl.

Since the polysiloxane is dissolved in an organic solvent, any particle size may be used, but in order to shorten the process time and increase efficiency, it is preferable to use an average particle size of 200 μm or less. When the average particle diameter exceeds 200 µm, it takes longer to dissolve.

As the carbon source, one or more selected from the group consisting of phenol resins, xylene resins, and combinations thereof can be used. In the present invention, the "combination" is a concept including both a mixture of each resin powder and a blend of each resin.

Since the carbon source is dissolved in an organic solvent, any particle size may be used, but in order to shorten the process time and increase efficiency, it is preferable to use an average particle size of 200 μm or less. When the average particle diameter exceeds 200 µm, it takes longer to dissolve.

The organic solvent is not particularly limited as long as it dissolves both polysiloxane powder and carbon source, which are silicon sources, and specifically, methanol, ethanol, propanol, butanol or acetone, etc. It can be used individually or in mixture of 2 or more types.

The organic solvent may be used in an amount of 50 to 300 parts by weight based on 100 parts by weight of the total content of the silicon source and the carbon source. When the organic solvent is used in less than 50 parts by weight, the silicon source and the carbon source are not sufficiently dissolved, and when it exceeds 300 parts by weight, it is not economical because it takes a lot of time in the drying step.

By dissolving the silicon source and carbon source in an organic solvent as described above, it is possible to prepare a solution in which silicon and carbon precursors are uniformly mixed in a molecular shape, thereby significantly improving the reactivity of the silicon source and the carbon source. have. In this case, a method of dissolving and mixing the silicon source and the carbon source in an organic solvent includes a magnetic stirring bar, or a method of using a SiC ball and a polypropylene jar.

In the present invention, the second step is a step of completely drying the mixed solution prepared in the first step.

The drying is preferably carried out slowly at 25 to 50 ℃, preferably 40 to 50 ℃. If the temperature is less than 25 ° C, the drying time is long, and if it exceeds 50 ° C, the dried polysiloxane may be softened and separated from the carbon source.

The drying is preferably carried out while stirring. Specifically, the mixed solution is stirred using a magnetic sterling bar, and the temperature of the hot plate is maintained at 25 to 50 ° C. to allow it to be dried slowly until complete drying, and does not cause separation of the silicon source and the carbon source. Any drying method may be used. If not completely dried, the silicon source and the carbon source may be separated during the curing performed after the second step.

In addition, the first step and the second step may be performed simultaneously.

In the present invention, the third step is a step of cross-linking and curing the polysiloxane which is the silicon source in the mixture dried in the second step.

 In the mixture dried in the second step, the silicon source polysiloxane and the carbon source are uniformly mixed in the molecular form. However, if the treatment temperature of the pyrolysis and carbon heat reduction step performed after the third step exceeds the softening temperature of the polysiloxane, there is a possibility that the polysiloxane dried in the second step again melts and eventually separates from the carbon source. have. Therefore, crosslinking curing is essential to prevent the fusion of polysiloxanes.

The curing is preferably carried out for 2 to 48 hours at a temperature of 140 to 200 ℃ under 0.5 to 1 atm. If the temperature is less than 140 ℃ hardening is not made enough, the polysiloxane is melted during the subsequent step carried out after the third step, if the temperature exceeds 200 ℃ no cross-linking curing is ineffective because it is inefficient. In addition, when the curing time is less than 2 hours, crosslinking curing is not sufficiently achieved, and when the curing time exceeds 48 hours, no further crosslinking curing is performed, which is inefficient.

In addition, the curing is preferably carried out by heating at a rate of 0.1 to 2 ℃ / min. If the heating rate is less than 0.1 ℃ / min, the curing time takes too long, if it exceeds 2 ℃ / min, the curing rate proceeds too fast, the curing of the polysiloxane is not sufficiently made, there is a possibility that the polysiloxane is melted.

In the curing, a method of curing by electron beam or radiation irradiation may be used. In addition, although the catalyst may be further added to promote curing of the polysiloxane, it is preferable to carry out without using a catalyst in order to prepare a high purity silicon carbide nanopowder.

In the present invention, the fourth step is to thermally decompose the mixture cured in the third step.

The pyrolysis is preferably carried out by heating at a temperature of 700 to 1200 ℃ for 0.5 to 3 hours in the presence of an inert gas such as nitrogen or argon. If the temperature is below 700 ° C., pyrolysis is insufficient. If it is above 1200 ° C., hard aggregates are formed in the pyrolysis residue.

The pyrolysis is preferably carried out by heating at a rate of 0.5 to 10 ℃ / min. If the heating rate is less than 0.5 ℃ / min is too inefficient due to the pyrolysis time is too long, if it exceeds 10 ℃ / min, some elements of the polysiloxane is released as a gas without being sufficiently decomposed during heating, and some of the silicon source and carbon source Lost.

The polysiloxane cured through the thermal decomposition as described above is converted to amorphous silicon oxycarbide (Siicon oxicarbide, SiO _x C _y ), the phenol resin, xylene resin or a mixture thereof as a carbon source is converted to carbon (C) to silicon oxycarbide And a mixture of carbons.

In the present invention, the fifth step is a carbon heat reduction of a mixture of amorphous silicon oxycarbide (SiO _x C _y ) and carbon pyrolyzed in the fourth step. At this time, the carbon heat reduction reaction is shown in Scheme 2 below.

SiO _x C _y + (1-y + x) C → SiC + xCO ↑

The carbon heat reduction is preferably performed by heating for 0.5 to 3 hours at a temperature of 1450 to 1600 ℃ in the presence of an inert gas. When the reaction temperature is less than 1450 ℃, the reduction reaction is not made sufficiently, and when the temperature exceeds 1600 ℃ it is difficult to control the average particle diameter of the silicon carbide nano-powder manufactured to less than 80 nm. In addition, if the reaction time is less than 0.5 hours, the reduction reaction is not made sufficiently, if more than 3 hours the average particle diameter of the silicon carbide nano-powder to be produced exceeds 80 nm.

The carbon heat reduction is preferably performed by heating at a rate of 1 to 20 ℃ / min. If the heating rate is less than 1 ℃ / min is too inefficient due to the reduction reaction time is too long, the reduction reaction is not sufficiently achieved if it exceeds 20 ℃ / min.

The fourth and fifth steps may be continuously performed in the same heating apparatus.

The silicon carbide nanopowder of the present invention is prepared by the method for producing the silicon carbide nanopowder of the present invention comprising the first step to the fifth step, and has an average particle diameter of 10 to 80 nm, preferably 20 to 80 nm, and purity Is more than 99.99%. If the average particle diameter is less than 10 nm, the filling density is low, and the sinterability is lowered. If the average particle diameter is more than 80 nm, it is difficult to produce silicon carbide nanoceramic having a crystal grain size of 100 nm or less.

As described above, the silicon carbide nanopowder has a high surface energy by finely controlling the average particle diameter of 80 nm or less, thereby allowing the production of a dense material having excellent sinterability and lower temperature than the conventional one.

Hereinafter, preferred examples are provided to aid the understanding of the present invention, but the following examples are merely for exemplifying the present invention, and it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present invention. It is natural that such variations and modifications fall within the scope of the appended claims.

Example 1

62 g of polysiloxane powder having an average particle diameter of 44 µm as a silicon source and a weight average molecular weight of 1500, and 38 g of a phenol resin powder having an average particle diameter of 44 µm as a carbon source were dissolved in 200 ㏄ acetone solvent, and magnetic sterling. Mix using bar. After confirming that the polysiloxane powder and the phenol resin powder were completely dissolved to form a molecularly uniform mixture, the temperature of the hot plate was raised to 45 ° C. and the mixture was completely dried while stirring the magnetic stirrer bar. The dried mixture was heated to 170 ° C. at a rate of 0.5 ° C./min under atmospheric pressure, and maintained at 170 ° C. for 24 hours to crosslink the polysiloxane in the mixed solution. The cured mixture was pyrolyzed by heating to 700 ° C. under an argon atmosphere at a rate of 3 ° C./min and holding at 700 ° C. for 1 hour. The pyrolyzed mixture was then heated to 1450 ° C. at a rate of 3 ° C./min and maintained at 1450 ° C. for 1 hour for carbon thermal reduction.

As a result of observing the prepared silicon carbide nanopowder with a transmission electron microscope, the average particle diameter was 20 nm as shown in FIG. In addition, as a result of analysis using inductively coupled plasma mass spectrometry, the total impurity content of Al, Ca, Na, K, Cr, Fe, Ni, Cu, B, Ti, etc. is less than 50 ppm. Was over 99.995%.

Example 2

60 g of polysiloxane powder having a mean particle size of 44 µm as a silicon source and a weight average molecular weight of 2000 represented by Formula 1, and 40 g of xylene resin powder having an average particle diameter of 88 µm as a carbon source were dissolved in 180 kPa of a butanol solvent and magnetic sterling. Mix using bar. After confirming that the polysiloxane powder and the xylene resin powder were completely dissolved to prepare a molecularly uniform mixture, the temperature of the hot plate was raised to 50 ° C. and the mixture was completely dried while stirring the magnetic stirrer bar. The dried mixture was heated to 200 ° C. at a rate of 1.0 ° C./min under atmospheric pressure, and maintained at 200 ° C. for 6 hours to crosslink the polysiloxane in the mixed solution. The cured mixture was pyrolyzed by heating to 750 ° C. under an argon atmosphere at a rate of 3 ° C./min and held at 750 ° C. for 2 hours. The pyrolyzed mixture was then heated to 1600 ° C. at a rate of 5 ° C./min, and carbon thermally reduced by holding at 1600 ° C. for 2 hours.

The prepared silicon carbide nanopowder was observed with a transmission electron microscope, and the average particle diameter was 70 nm. In addition, as a result of analysis using ICP mass spectrometry, the total impurity content of Al, Ca, Na, K, Cr, Fe, Ni, Cu, B, Ti, and the like was 50 ppm or less, and the purity was 99.995% or more.

Example 3

66 g of polysiloxane powder having an average particle diameter of 44 μm as a silicon source and 2900 weight average molecular weight, 17 g of xylene resin powder having an average particle diameter of 88 μm as a carbon source, and 17 g of phenol resin powder having an average particle diameter of 88 μm Was dissolved in 220 kPa of methanol solvent and mixed using a polypropylene bottle and SiC ball. After confirming that the polysiloxane powder, the xylene resin, and the phenol resin powder were completely dissolved to form a molecularly uniform mixture, the temperature of the hot plate was raised to 50 ° C., and the mixture was completely dried while stirring the magnetic sterling bar. The dried mixture was heated to 160 ° C. at a rate of 2.0 ° C./min under atmospheric pressure, and maintained at 160 ° C. for 48 hours to cross-cure the polysiloxane in the mixed solution. The cured mixture was pyrolyzed by heating to 1000 ° C. under an argon atmosphere at a rate of 2 ° C./min and holding at 1000 ° C. for 1 hour. The pyrolyzed mixture was then heated to 1500 ° C. at a rate of 5 ° C./min, and carbon-heat reduced by holding at 1500 ° C. for 3 hours.

As a result of observing the manufactured silicon carbide nanopowder with a transmission electron microscope, the average particle diameter was 30 nm. In addition, as a result of analysis using the ICP mass spectrometry method, the total impurity content of Al, Ca, Na, K, Cr, Fe, Ni, Cu, B, Ti and the like was 30 ppm or less, and the purity was 99.995% or more.

Example 4

62 g of polysiloxane powder having an average particle diameter of 44 µm as a silicon source and 1500 g of the average molecular weight represented by Formula 2, and 38 g of a phenol resin powder having an average particle diameter of 44 µm as a carbon source were dissolved in acetone solvent of 200 kPa, and magnetic sterling. Mix using bar. After confirming that the polysiloxane powder and the phenol resin powder were completely dissolved to form a molecularly uniform mixture, the temperature of the hot plate was raised to 45 ° C. and the mixture was completely dried while stirring the magnetic stirrer bar. The dried mixture was heated to 170 ° C. at a rate of 0.5 ° C./min under atmospheric pressure, and maintained at 170 ° C. for 24 hours to crosslink the polysiloxane in the mixed solution. The cured mixture was pyrolyzed by heating to 700 ° C. under an argon atmosphere at a rate of 3 ° C./min and holding at 700 ° C. for 1 hour. The pyrolyzed mixture was then heated to 1450 ° C. at a rate of 3 ° C./min and maintained at 1450 ° C. for 1 hour for carbon thermal reduction.

The prepared silicon carbide nanopowder was observed with a transmission electron microscope, and the average particle diameter was 80 nm. In addition, as a result of analysis using the ICP mass spectrometry method, the total impurity content of Al, Ca, Na, K, Cr, Fe, Ni, Cu, B, Ti and the like was 100 ppm or less and the purity was 99.99% or more. That is, the purity was slightly lowered from 99.995% to 99.99% as compared to Example 1 using the polysiloxane represented by the formula (1).

Comparative Example 1

60 g of silica powder having an average particle diameter of 1 μm as a silicon source and 60 g of phenol resin powder having an average particle diameter of 44 μm as a carbon source were dissolved in a 300 kPa acetone solvent and mixed using a magnetic sterling bar. After confirming that the phenol resin powder was completely dissolved and the silica powder was dispersed, a hot liquid was heated to 45 ° C., and the mixture was dried while stirring the magnetic stirrer bar. The dried mixture was pyrolyzed by heating to 700 ° C. under an argon atmosphere at a rate of 3 ° C./min and holding at 700 ° C. for 1 hour. The pyrolyzed mixture was then heated to 1450 ° C. at a rate of 3 ° C./min and maintained at 1450 ° C. for 1 hour for carbon thermal reduction.

As a result of observing the manufactured silicon carbide powder with a scanning electron microscope, the average particle diameter was 450 nm. In addition, as a result of analysis using ICP mass spectrometry, the total impurity content of Al, Ca, Na, K, Cr, Fe, Ni, Cu, B, Ti, W, etc. was 1000 ppm or more and the purity was less than 99.9%. .

Comparative Example 2

62 g of polysiloxane powder having an average particle diameter of 44 µm as a silicon source and a weight average molecular weight represented by the formula (2000), and 30 g of carbon black having an average particle diameter of 20 nm as a carbon source were added to a 300 ㏄ acetone solvent. And mixed using a magnetic sterling bar. After confirming that the polysiloxane powder was completely dissolved and the carbon black dispersed mixture was prepared, the temperature of the hot plate was raised to 45 ° C. and the mixture was completely dried while stirring the magnetic stirrer bar. The dried mixture was heated to 170 ° C. at a rate of 0.5 ° C./min under atmospheric pressure, and maintained at 170 ° C. for 24 hours to crosslink the polysiloxane in the mixed solution. The cured mixture was pyrolyzed by heating to 700 ° C. under an argon atmosphere at a rate of 3 ° C./min and holding at 700 ° C. for 1 hour. The pyrolyzed mixture was then heated to 1450 ° C. at a rate of 3 ° C./min and maintained at 1450 ° C. for 1 hour for carbon thermal reduction.

As a result of observing the manufactured silicon carbide powder with a scanning electron microscope, the average particle diameter was 300 nm. In addition, as a result of analysis using ICP mass spectrometry, the total impurity content of Al, Ca, Na, K, Cr, Fe, Ni, Cu, B, Ti, W, etc. was 1200 ppm or more and the purity was less than 99.9%. .

Comparative Example 3

62 g of polysiloxane powder having a mean particle diameter of 44 µm as a silicon source and a weight average molecular weight of 2000 represented by Formula 1, and 38 g of a phenol resin powder having an average particle diameter of 44 µm as a carbon source were dissolved in acetone solvent of 200 kPa, and magnetic sterling. Mix using bar. After confirming that the polysiloxane powder and the phenol resin powder were completely dissolved to form a molecularly uniform mixture, the temperature of the hot plate was raised to 45 ° C. and the mixture was completely dried while stirring the magnetic stirrer bar. The dried mixture was pyrolyzed by heating to 700 ° C. under an argon atmosphere at a rate of 3 ° C./min and holding at 700 ° C. for 1 hour without curing. The pyrolyzed mixture was then heated to 1450 ° C. at a rate of 3 ° C./min and maintained at 1450 ° C. for 1 hour for carbon thermal reduction.

As a result of X-ray diffraction analysis, the prepared silicon carbide powder contained unreacted carbon and SiO ₂ phase together with silicon carbide powder, and the average particle diameter was 580 nm as observed by scanning electron microscope. In addition, as a result of analysis using the ICP mass spectrometry method, the total impurity content of Al, Ca, Na, K, Cr, Fe, Ni, Cu, B, Ti and the like was 1000 ppm or more and the purity was 99.9% or more.

1 is a transmission electron micrograph of the silicon carbide nano powder according to Example 1 of the present invention.

Claims (13)

As a method for producing silicon carbide nano powder, A first step of dissolving at least one carbon source selected from the group consisting of polysiloxane powders, phenol resins, xylene resins, and combinations thereof in an organic solvent to produce a uniform mixed solution; A second step of drying the prepared liquid mixture; A third step of curing the polysiloxane in the dried mixture; A fourth step of pyrolyzing the mixture cured polysiloxane; And Method for producing a silicon carbide nano powder, characterized in that it comprises a fifth step of thermally decomposing the pyrolyzed mixture. The method of claim 1, The silicon carbide nano powder has an average particle diameter of 10 to 80 nm, the purity of the method of producing a silicon carbide nano powder, characterized in that more than 99.99%. The method of claim 1, The polysiloxane powder is at least one selected from the group consisting of a compound represented by the following formula (1), a compound represented by the formula (2) and copolymers thereof, and a silicon carbide nanopowder having a weight average molecular weight of 150 to 5000. Manufacturing method. [Formula 1] [RSiO _1.5 ] _n In Formula 1, R is a hydrogen atom, a hydroxyl group or an alkyl group, n is a value determined by the weight average molecular weight of the polysiloxane is an integer; [Formula 2] [R ₂ SiO] _n In Formula 2, R is each independently a hydrogen atom, an alkyl group, an alkenyl group or a cyclic group, n is a value determined by the weight average molecular weight of the polysiloxane. The method according to claim 1 or 3, The polysiloxane powder is a method for producing silicon carbide nanopowder, characterized in that the average particle diameter is 200 ㎛ or less. delete The method of claim 1, The carbon source is a method for producing silicon carbide nanopowder, characterized in that the average particle diameter is 200 ㎛ or less. The method of claim 1, The organic solvent is a method for producing silicon carbide nanopowder, characterized in that at least one selected from the group consisting of methanol, ethanol, propanol, butanol and acetone. The method according to claim 1 or 7, The organic solvent is a method for producing silicon carbide nanopowder, characterized in that used in 50 to 300 parts by weight based on 100 parts by weight of the total content of the polysiloxane powder and carbon source. The method of claim 1, The drying of the second step is a method for producing silicon carbide nanopowder, characterized in that is carried out at a temperature of 25 to 50 ℃ while stirring the mixed solution. The method of claim 1, The hardening of the third step is a method for producing silicon carbide nanopowder, characterized in that the heating at a rate of 0.1 to 2 ℃ / min at 0.5 to 1 atm, carried out for 2 to 48 hours at a temperature of 140 to 200 ℃ . The method of claim 1, The pyrolysis of the fourth step is prepared by heating at a rate of 0.5 to 10 ℃ / min in the presence of an inert gas, by heating for 0.5 to 3 hours at a temperature of 700 to 1200 ℃ Way. The method of claim 1, In the fifth step, the carbon heat reduction is performed by heating at a rate of 1 to 20 ° C./min in the presence of an inert gas, and heating the same at a temperature of 1450 to 1600 ° C. for 0.5 to 3 hours. Manufacturing method. A silicon carbide nanopowder manufactured by the method according to claim 1, having an average particle diameter of 10 to 80 nm and a purity of 99.99% or more.

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