KR20110021530A - High purity silicon carbide manufacturing method and system - Google Patents

Abstract

PURPOSE: A method and a system for manufacturing high purity silicon carbide powder are provided to be easily implemented under low pressure and low temperature. CONSTITUTION: A mixture composed of silicon source and carbon source is generated in a mixer(110). The mixture is heated in a sealed crucible(120) under the 0.03 to 0.5torr of pressure and the 1300 to 1900 degrees Celsius of temperature. The weight ratio of the silicon source and the carbon source is between 1:1 and 4:1. The silicon source is selected from fumed silica, silica sol, silica gel, fine silica, and quartz powder. The carbon source is selected from carbon black, carbon nano-tube, fullerene, a penol resin, a franc resin, a xylene resin, a monomer containing polyimide, polyurethane, polyacrylonitrile, polyvinyl alcohol, and polyvinyl acetate, a prepolymer, cellulose, pitch and tar.

Description

High Purity Silicon Carbide Powder Manufacturing Method and System {HIGH PURITY SILICON CARBIDE MANUFACTURING METHOD AND SYSTEM}

The present invention relates to a method and system for producing high purity silicon carbide powder.

Silicon carbide (SiC) and boron (B) are reinforcement materials with high tensile modulus. If Al ₂ O ₃ is a representative of oxide ceramics, SiC is widely used as a representative of non-oxide ceramics. SiC fiber is actively pioneered as a reinforcing material for ceramic and metal composite materials. Boron fiber is mainly used as a high-performance epoxy reinforcing material.

In particular, SiC, which has excellent physical properties, will become a popular reinforcing material if only a much more expensive price problem is solved than other reinforcing materials.

Silicon carbide (SiC) is a composite material and is the most important carbide in the field of ceramics. Silicon carbide has a β phase having a cubic crystal structure and an α phase having a hexagonal crystal structure. The β phase is stable in the temperature range of 1400-1800 ° C., and the α phase is formed at 2000 ° C. or higher.

The molecular weight of SiC is 40.1, specific gravity is 3.21, and it decomposes at 2500 degreeC or more.

Since silicon carbide has been the first successful atmospheric pressure sintering by the addition of boron and carbon by Prochazka of GE in the US in the 1970s, SiC is a high-temperature structural material with high temperature strength, excellent wear resistance, oxidation resistance, corrosion resistance and creep resistance. It is a material that attracts attention, and is a high-grade ceramic material currently widely used in mechanical seals, bearings, various nozzles, high temperature cutting tools, fireproof plates, abrasives, reducing materials in steelmaking, and lightning arresters.

Conventional techniques for preparing such SiC powders include the Acheson method, the direct carbonization method, the liquid phase polymer pyrolysis method, and the high temperature auto combustion synthesis method.

The prior art is a silicon carbide by heat treatment at 1350 ℃ to 2000 ℃ by mixing a solid silicon source, such as SiO ₂ , Si, carbon, graphite type carbon source. These prior arts have problems with SiC powder recovery and have limitations of purity and relatively high synthesis temperatures.

In addition, it is difficult to mass-produce silicon carbide, and additional processes such as classification cleaning are required, resulting in a high price of silicon carbide powder produced due to a long manufacturing time.

Therefore, there is an urgent need for a manufacturing method capable of producing silicon carbide powder at a lower cost in the structure of importing all the foreign materials as in Korea, and thus, high-purity uniform silicon carbide powder.

The present invention has been made to solve the above problems, an object of the present invention is to provide a method and system for producing high-purity silicon carbide powder which can be produced inexpensively and easily.

The present invention provides an ultra-high purity silicon carbide manufacturing method for solving the above problems, comprising the steps of: (a) generating a mixture consisting of a silicon source and a carbon source in a mixer; And (b) heating the mixture to a vacuum degree of 0.03 torr or more and 0.5 tor or less, a temperature of 1300 ° C. or more and 1900 ° C. or less to synthesize silicon carbide (SiC) powder.

In addition, the mass ratio of the silicon source and the carbon source of the step (a) is characterized in that 1: 1 to 4: 1.

Here, the silicon source of step (a) is selected from at least one of fumed silica (Fumed Silica), silica sol (silica sol), silica gel (silica gel), fine silica (silica), and quartz powder,

In addition, the carbon source is carbon black (carbon black), carbon nanotubes, praren, phenol (penol) resin, franc resin, xylene (xylene) resin, polyimide (polyimide), polyurethane (polyurethane), poly Acrylonitrile, polyvinyl alcohol, monomers including polyvinyl acetate, prepolymers, celluloses, sugars, pitches, and tars It is characterized in that at least one of the selected.

In addition, the heating temperature of step (b) is characterized in that more than 1600 ℃ 1900 ℃.

In addition, the heating time of step (b) is characterized in that 3 hours.

In particular, the high-purity silicon carbide powder production method further comprises the step of carbonizing the carbon source included in the mixture by heating the mixture between the steps (a) and (b). do.

Here, the carbonizing step is characterized in that the carbonization at a temperature of 700 ℃ to 1200 ℃.

In addition, the carbonizing step is a high-purity silicon carbide powder production method, characterized in that the carbonization at a temperature of 900 ℃ 1100 ℃.

In addition, the ultra-high purity silicon carbide production system for solving the above-described problems of the present invention, a mixer for producing a mixture consisting of a silicon source and a carbon source; And a hermetically sealed crucible for synthesizing silicon carbide (SiC) by heating the mixture to a degree of vacuum above 0.03 torr to 0.5 torr or less, a temperature of 1300 ° C. or more and 1900 ° C. or less.

In addition, the mass ratio of the silicon source and the carbon source is characterized by being 1: 1 to 4: 1.

In addition, the silicon source is dry silica (Fumed Silica), the carbon source is characterized in that the carbon black.

In addition, the heating temperature of the crucible is characterized in that more than 1600 ℃ 1900 ℃.

In addition, the heating time is characterized in that 3 hours.

In particular, the high-purity silicon carbide powder production system is characterized in that it further comprises a carbonizer for heating the mixture to carbonize the carbon source included in the mixture (carbonization).

In addition, the carbonizer is characterized in that the carbonization at a temperature of 700 ℃ to 1200 ℃.

In addition, the carbonizer is characterized in that the carbonization at a temperature of 900 ℃ 1100 ℃.

According to the present invention, it is possible to manufacture at a lower pressure and lower temperature than the conventional silicon carbide manufacturing method, thereby reducing the process cost and easily obtaining silicon carbide powder of high purity.

Hereinafter, with reference to the accompanying drawings will be described in detail a method and system for producing high purity silicon carbide powder according to a preferred embodiment. In the following description, well-known functions or constructions are not described in detail to avoid unnecessarily obscuring the subject matter of the present invention.

1 is a block diagram of a high-purity silicon carbide powder manufacturing method according to a preferred embodiment of the present invention.

Referring to FIG. 1, first, a silicon source and a carbon source are prepared, and in particular, it is preferable to prepare fumed silica as a silicon source and carbon black as a carbon source (S1). However, the silicon source and the carbon source are not limited thereto, and silica sol and silicon dioxide (silica gel, fine silica, quartz powder) may be used as the silicon source. In addition, the carbon source may be a solid carbon such as carbon nanotubes or prarene, or an organic compound having a high residual carbon ratio, for example, a phenol resin, a franc resin, a xylene resin, a polyimide, Monomers or prepolymers of resins such as polyurethane, polyacrylonitrile, polyvinyl alcohol, polyvinyl acetate, prepolymers, cellulose, sugars, and pitch ), Tar, and mixtures thereof may also be used.

Thereafter, such a silicon source and a carbon source are mixed. In particular, 40 g of dry silica as a silicon source and 18 g of carbon black as a carbon source are mixed (S2). When a solid carbon source is used here, the mass ratio of the silicon source and the carbon source is preferably 1: 1 or more and 4: 1 or less. In addition, when a carbon source of an organic material is used, a carbon source of about twice as much mass as a solid carbon source is required, but a liquid carbon source may have some difference depending on the amount of carbon produced during carbonization. Then, the mixture of the silicon source and the carbon source is heated to carbonize the carbon source included in the mixture (S3). It is preferable that such a carbonization process is temperature 700 degreeC or more and 1200 degrees C or less. In addition, it is more preferable to maintain the temperature of the carbonization process at 900 ° C or more and 1100 ° C or less, and the carbonization process may be omitted if the carbon source is not an organic carbon material.

Thereafter, the mixture is heated to a vacuum temperature of more than 0.03torr and less than 0.5torr, and a temperature of 1300 ° C or more and 1900 ° C or less to synthesize silicon carbide (SiC) powder (S4). The heating time is preferably about 3 hours, but is not necessarily limited thereto. Moreover, it is more preferable that heating temperature is 1600 degreeC or more and 1900 degrees C or less. In the synthesis process conditions, the vacuum degree is preferably 1 tor or less, and more preferably heat treatment in a vacuum atmosphere of 0.1 tor or less. However, when the degree of vacuum is 0.03torr or less, mechanical load is high in mass production equipment, and additional equipment is required, making maintenance of equipment difficult and expensive, which is not preferable.

By using this process of the present invention, high purity hydrocarbon powder can be produced at low cost. These effects are shown in Table 1 below in comparison with the case using the conventional method.

Impurity Content (ppm) Comparative example Example 1 Example 2 B 0.1 0.1 0.1 Na 5 0.01 0.5 K 2 0.01 0.5 Al 3 0.5 One Cr One 0.1 0.1 Fe One 0.1 0.1 Ni One 0.1 0.5 Cu 0.1 0.1 0.1 W One 0.1 0.5 Ti 0.05 0.05 0.05 Ca 10 0.5 One

Referring to Table 1, the comparative example shows the case of producing a hydrocarbon powder in a conventional manner. And Example 1 and Example 2 is a case where the hydrocarbon powder is produced using the production method according to the present invention. Here, the common condition in all cases is that 40 g of dry silica having an average particle diameter of 40 nm is selected as the silicon source, and 18 g of carbon black having an average input of 20 nm is selected as the carbon source to perform the mixing step, and the carbonization step is omitted.

In addition, as a difference, a comparative example synthesize | combined three hours at the temperature of 1700 degreeC in argon (Ar) gas atmosphere in a crucible. On the other hand, Example 1 is synthesized in the crucible at 0.1torr or more and 0.5torr or less, 3 hours at a temperature of 1700, Example 2 is synthesized in the crucible for 3 hours at 0.1torr or more and 0.5torr or less, temperature 1600.

As can be seen from the results of the experiment, the impurity contents are much less in Examples 1 and 2 than in Comparative Examples. Therefore, in the case of using the present invention, it is possible to reduce the production cost by using a vacuum state without using argon gas, and to obtain high purity hydrocarbon powder with much less impurities.

2 is a block diagram of a high purity hydrocarbon powder production system according to a preferred embodiment of the present invention.

The high purity hydrocarbon powder production system 100 includes a mixer 110, a crucible 120, and a carbonizer 130. The mixer mixes the silicon source and the carbon source to produce a mixture consisting of the silicon source and the carbon source. Here, the silicon source and the carbon source may be selected from various kinds as described in FIG. 1. In particular, it is preferable that the mass ratio of a silicon source and a carbon source is 1: 1 or more and 4: 1 or less. In addition, the carbonizer 130 is coupled to the mixer 110 and the crucible 120 and carbonizes the carbon source contained in the mixture. Moreover, the temperature carbonized by the carbonizer 130 becomes like this. Preferably it is 700 degreeC or more and 1200 degrees C or less, More preferably, it carbonizes at 900 degreeC or more and 1100 degrees C or less. In particular, the carbonizer 130 may be omitted if the carbon source of the mixture is not an organic carbon material, in which case the mixture moves directly from the mixer 110 to the crucible 120.

In addition, the crucible 120 heats a mixture to more than a vacuum degree of 0.03 torr and 0.5 torr or less, the temperature 1300 degreeC or more and 1900 degrees C or less, and synthesize | combins silicon carbide (SiC) powder. In particular, it is more preferable that the heating temperature of a crucible is 1600 degreeC or more and 1900 degrees C or less. In addition, it is preferable that the heating time in the crucible 130 is 3 hours.

By using such a high purity hydrocarbon production system, low cost and high purity hydrocarbon powder can be produced.

In the foregoing detailed description of the present invention, specific examples have been described. However, various modifications are possible within the scope of the present invention. The technical spirit of the present invention should not be limited to the above-described embodiments of the present invention, but should be determined by the claims and equivalents thereof.

1 is a block diagram of a high-purity silicon carbide powder production method according to a preferred embodiment of the present invention

Figure 2 is a block diagram of a configuration of a high purity hydrocarbon powder production system according to an embodiment of the present invention

Description of the Related Art [0002]

100: high purity hydrocarbon powder production system 110: mixer

120: crucible 130: carbonizer

Claims (8)

(a) producing a mixture of silicon and carbon sources in a mixer; And (b) heating the mixture to a vacuum degree of 0.03 torr or more and 0.5 tor or less, a temperature of 1300 ° C. or more and 1900 ° C. or less to synthesize silicon carbide (SiC) powder. The method of claim 1, Mass ratio of the silicon source and the carbon source of the step (a) is 1: 1 to 4: 1 characterized in that the high purity silicon carbide powder production method. 3. The method of claim 2, The silicon source of step (a) is selected from at least one of fumed silica (Fumed Silica), silica sol (silica sol), silica gel (silica gel), fine silica (silica), and quartz powder, The carbon source is carbon black, carbon nanotube, praren, phenol resin, franc resin, xylene resin, polyimide, polyurethane, polyacrylo At least one of nitrile (polyacrylonitrile), polyvinyl alcohol, monomers including polyvinyl acetate, prepolymer, cellulose, sugar, pitch, and tar The high purity silicon carbide powder manufacturing method characterized by the above-mentioned. The method according to any one of claims 1 to 3, Between step (a) and step (b), Heating the mixture to carbonize the carbon source contained in the mixture (carbonization) further comprising the step of producing a high-purity silicon carbide powder. The method of claim 4, wherein The carbonizing step is a high-purity silicon carbide powder production method, characterized in that the carbonization at a temperature of 700 ℃ 1200 ℃. A mixer for producing a mixture consisting of a silicon source and a carbon source; And And a sealed crucible for synthesizing silicon carbide (SiC) by heating the mixture to a vacuum degree of 0.03 torr or more and 0.5 tor or less, a temperature of 1300 ° C. or more and 1900 ° C. or less. The method of claim 6, Mass ratio of the said silicon source and the said carbon source is 1: 1 or more and 4: 1 or less, The high purity silicon carbide powder manufacturing system characterized by the above-mentioned. The method according to claim 6 or 7, The silicon source is selected from at least one of fumed silica (Fumed Silica), silica sol (silica sol), silica gel (silica gel), fine silica (silica), and quartz powder, The carbon source is carbon black, carbon nanotube, praren, phenol resin, franc resin, xylene resin, polyimide, polyurethane, polyacrylo At least one of nitrile (polyacrylonitrile), polyvinyl alcohol, monomers including polyvinyl acetate, prepolymer, cellulose, sugar, pitch, and tar High purity silicon carbide powder production system, characterized in that selected.

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