KR20140119467A - Silicon carbide powder and method for preparing silicon carbide powder - Google Patents

Abstract

The present invention relates to silicon carbide powder and a method for preparing silicon carbide powder. The method for preparing silicon carbide powder includes a step of preparing mixture powder mixing a liquid polymer-based carbon source and a solid silicon source, a step of forming a silicon carbide precursor by performing a first degreasing process on the mixture powder, a step of milling the silicon carbide precursor, and a step of forming silicon carbide precursor by heating the silicon carbide precursor after the milling step.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a silicon carbide powder and a method for producing the silicon carbide powder,

The present invention relates to a process for producing a silicon carbide powder and a silicon carbide powder.

Silicon carbide (SiC) is physically and chemically stable, has good heat resistance and thermal conductivity, and has high temperature stability, high temperature strength and abrasion resistance. Accordingly, silicon carbide is widely used as a material for industrial structural materials, and recently it has also been applied to semiconductor devices.

The silicon carbide powder is divided into a β-phase silicon carbide powder having a cubic crystal structure and an α-phase silicon carbide powder having a hexagonal crystal structure according to the crystal structure.

The α-phase silicon carbide powder is stable at a temperature of over 2000 ㅀ C and can be used for grinding, abrasive, refractory, etc. The β-phase silicon carbide powder is formed by the irreversible transfer of α-form at 1800 ~ 2000 ㅀ C and can be used as raw material for sintering.

The silicon carbide powder is produced by synthesizing a silicon source and a carbon source, and can be manufactured by an Acheson method, a carbon thermal reduction method, a CVD (Chemical Vapor Deposition) method, or the like.

On the other hand, in the case of dry mixing in which a solid silicon source and a liquid carbon source are mixed without using a solvent, coagulation phenomena may occur between the silicon particles and the carbon particles. Such agglomeration phenomenon interferes with the uniform grain growth of the silicon carbide powder and can act as a cause of forming powder having uneven particle size and large scattering.

Accordingly, there is a need for a method for preventing abnormal grain growth and enabling uniform grain growth by minimizing coagulation phenomena between silicon particles and carbon particles during dry mixing.

Korean Patent Laid-Open No. 10-2012-0113949 (Oct. 16, 2012)

Disclosure of Invention Technical Problem [8] The present invention provides a method for producing silicon carbide powder having uniform particle size and dispersibility.

The method for preparing a silicon carbide powder according to an embodiment of the present invention includes preparing a mixed powder by mixing a liquid polymeric carbon source and a solid silicon source, A step of subjecting the silicon carbide precursor to a pulverizing process, and a step of heating the silicon carbide precursor after the pulverizing process to form a silicon carbide powder.

The silicon carbide powder according to an embodiment of the present invention has a particle size (D ₅₀ ) of 1 탆 to 3 탆 and a scattering (D ₉₀ / D ₁₀ ) of 7 to 10.

According to the embodiment of the present invention, the pulverization process is performed on the mixed powder after the degreasing process to minimize the powder agglomeration, so that the change in the mixing ratio at the time of synthesis is minimized. Thereby, neck formation between fine powders is minimized to form a uniform temperature profile, and it is possible to manufacture a silicon carbide powder having a reduced particle size and a uniform particle size.

1 is a flow chart showing an example of a method for producing silicon carbide powder using a general dry mixing process.
FIG. 2 is a view for explaining the coagulation phenomenon occurring during dry mixing. FIG.
3 is a flowchart illustrating a method of manufacturing silicon carbide powder according to an embodiment of the present invention.

The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated and described in the drawings. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms including ordinal, such as second, first, etc., may be used to describe various elements, but the elements are not limited to these terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the second component may be referred to as a first component, and similarly, the first component may also be referred to as a second component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings, wherein like or corresponding elements are denoted by the same reference numerals, and redundant description thereof will be omitted.

1 is a flow chart showing an example of a method for producing silicon carbide powder using a general dry mixing process.

Referring to FIG. 1, a solid source (Si source) and a liquid carbon source (C source) are mixed (S100).

Next, a silicon carbide precursor is obtained from the mixed powder of the step S100 through a degreasing process (S110).

Thereafter, the silicon carbide precursor is heat-treated to form a fine silicon carbide powder (S120).

As described above, when a solid silicon source and a liquid carbon source are mixed through a dry mixing process without using a solvent, aggregation of the powder may occur.

FIG. 2 is a view for explaining the coagulation phenomenon occurring during dry mixing of a carbon source and a silicon source. FIG.

FIG. 2 (a) shows an example of aggregation phenomenon of a mixed powder containing a carbon source and a silicon source, and FIG. 2 (b) shows an example of a powder aggregation phenomenon after the degreasing step. 2 (c) shows an example of the synthesized silicon carbide powder.

Referring to FIG. 2, powder agglomeration occurs during mixing the carbon source and the silicon source, and the powder agglomeration phenomenon is maintained without being eliminated in the degreasing step. This powder aggregation phenomenon leads to a change in the mixing ratio of carbon and silicon due to nonuniform aggregation between molecules. Such a change in the mixing ratio leads to the formation of a neck, which is a connecting portion between the silicon carbide particles, and causes nonuniform powder production. In addition, the residual polymer present in the agglomerated mixed powder during the synthesis process may be discharged out of the system (outside the system, sample surface) and condensed, resulting in clogging or filter clogging.

Accordingly, in one embodiment of the present invention, the powder mixture solidified through the degreasing process is subjected to a pulverizing process to solve the powder aggregation.

FIG. 3 is a flowchart of a method for manufacturing silicon carbide powder according to an embodiment of the present invention.

Referring to FIG. 3, a Si source and a C source are mixed (S200).

Here, the molar ratio of silicon contained in the silicon source to carbon contained in the carbon source may be 1: 1.5 to 1: 3.

The silicon source means a silicon-providing material. The silicon source may be at least one selected from the group consisting of, for example, fumed silica, silica sol, silica gel, silica, quartz powder and mixtures thereof.

A carbon source means a carbon-providing material. The carbon source may be a liquid carbon source, a solid carbon source, or an organic carbon compound. The liquid carbon source may be, for example, a liquid polymer type phenol resin, pitch, or the like. As the solid carbon source, for example, at least one selected from the group consisting of graphite, carbon black, carbon nanotubes (CNT), fullerene, and mixtures thereof may be used. The organic carbon compound used as the carbon source may be selected from the group consisting of phenol resin, franc resin, xylene resin, polyimide, polyurethane, polyvinyl alcohol, But may be at least one selected from the group consisting of polyacrylonitrile, polyvinyl acetate, cellulose and mixtures thereof.

The silicon source and the carbon source can be mixed by a dry mixing process in which a solid silicon source and a liquid carbon source are mixed without using a solvent.

Next, a silicon carbide precursor is obtained from the mixed powder of the step S200 through a primary degreasing process (S210). The primary degreasing process may be carried out by, for example, maintaining the nitrogen atmosphere for a predetermined time (for example, 30 minutes to 5 hours) at, for example, 700 to 1000 ° C.

Next, a milling process is performed on the silicon carbide precursor (S220). The silicon carbide precursor solidified through the first degreasing process is easy to proceed with the grinding process.

The milling process is carried out using a super mixer, a ball mill, an attrition mill, a 3 roll mill, and the like. The pulverizing step may be carried out using a raw material to be introduced, that is, a silicon carbide ball (SiC ball) composed of the same raw material as the silicon carbide precursor, or a Teflon ball, in order to prevent impurities from being mixed. When Teflon balls are used, the impurities incorporated from the ball during the milling process can be evaporated and discharged during the heat treatment process of the synthesis process.

The ratio of the amount of the raw material to be introduced into the ball to the ball, that is, the silicon carbide precursor and the ball, may be 1: 1 to 1: 1.5 in consideration of the working efficiency, the capacity of the ball, and the like. The milling process may be conducted for a predetermined time (e.g., 0.5 to 30 hours) at a speed of 150 to 250 RPM, though not limited thereto.

As the milling process proceeds, powder agglomeration during the mixing process is minimized.

Next, a secondary degreasing process is performed to remove the residual polymer from the pulverized fine powder mixture (S230). The second degreasing process may be carried out by, for example, maintaining the atmosphere of argon (Ar) for a predetermined time (for example, 3 to 5 hours) at, for example, 800 to 900 ° C.

Next, the silicon carbide precursor from which the residual polymer is removed is heat-treated to form a fine silicon carbide powder (S240). Here, the heat treatment may be carried out by maintaining the atmosphere of argon (Ar) for a predetermined time (for example, 0.5 hour to 5 hours) under the condition of 1500 占 폚 to 1800 占 폚, for example, but not limited thereto.

Generally, the silicon carbide powder produced through the dry mixing process has a particle size (D ₅₀ ) of 0.7 μm to 5 μm and a scattering (D ₉₀ / D ₁₀ ) of 10 to 50.

On the other hand, the silicon carbide powder produced according to an embodiment of the present invention is a β-phase silicon carbide powder having a particle size (D ₅₀ ) of 1 μm to 3 μm and a scattering (D ₉₀ / D ₁₀ ) .

As described above, according to one embodiment of the present invention, the pulverization process is performed on the mixed powder after the degreasing process to minimize the powder agglomeration, so that the change in the mixing ratio at the time of synthesis is minimized. Accordingly, the formation of the neck between the fine powders is minimized, and the phenomenon that the thermal conductivity becomes uneven due to the formation of the neck is also minimized. Therefore, it is possible to manufacture a silicon carbide powder having a uniform temperature profile by forming a uniform temperature profile by reducing the temperature deviation due to uniform thermal conductivity, reducing scattering and having a uniform particle size.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims It can be understood that

Claims (1)

A silicon carbide powder having a particle size (D ₅₀ ) of 1 탆 to 3 탆 and a scattering (D ₉₀ / D ₁₀ ) of 7 to 10.

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