KR20150000316A - Silicon carbide powder - Google Patents

Abstract

Disclosed in the present invention is a mixed silicon carbide which includes a first silicon carbide powder and a second silicon carbide powder having different average diameters (D50), and has the concentration of total impurities of 5 ppm or less. Provided in the present invention is a mixed silicon carbide powder having the grain growth ratio controlled in the step of growing silicon carbide powder. The mixed silicon carbide powder according to an embodiment of the present invention comprises a first silicon carbide powder having D50 of 10-50 μm, and having D90/D10 of 5 or less; and a second silicon carbide powder having D50 of 100-400 μm, and having D90/D10 of 4 or less.

Description

Silicon Carbide Powder {SILICON CARBIDE POWDER}

The present invention relates to an ultra high purity silicon carbide mixed powder having a particle size range of two or more peaks.

Silicon carbide (SiC) is physically and chemically stable and has excellent heat resistance and thermal conductivity, and is excellent in high temperature stability, high temperature strength and abrasion resistance. Accordingly, silicon carbide is widely used as a structural material for industry, and recently it is also applied to the semiconductor industry. For this purpose, high purity silicon carbide powder is required.

The silicon carbide powder can be produced by an Acheson method, a carbon thermal reduction method, a CVD (Chemical Vapor Deposition) method, or the like. The silicon carbide powder thus produced has a low purity and requires a high purity treatment.

Various techniques for obtaining high purity silicon carbide powder have been proposed. For example, there is a method of improving the purity of silicon carbide by limiting the molar ratio of carbon to silicon.

The silicon carbide powders thus prepared are controlled in packing density by mixing the particles having a large particle size with the small particles at an appropriate ratio in order to increase the packing density.

However, in the process of pulverizing silicon carbide fine powder, impurities are introduced in the process of mixing particles having a large particle size and small particles, and since such impurities are very difficult to be controlled and controlled, it is impossible to obtain high quality silicon carbide such as a high purity sintered body or a single crystal raw material there is a problem.

The present invention provides a silicon carbide mixed powder in which the grain growth rate is controlled in the step of growing silicon carbide powder.

The present invention provides a silicon carbide mixed powder having a high purity with a particle size range of two or more peaks.

The silicon carbide mixed powder according to an embodiment of the present invention may include a first silicon carbide powder having a D ₅₀ of 10 μm to 50 μm and a D ₉₀ / D ₁₀ of 5 or less; And a second silicon carbide powder having a D ₅₀ of 100 탆 to 400 탆 and a D ₉₀ / D ₁₀ of 4 or less, wherein the total impurity concentration is 5 ppm or less.

In the silicon carbide mixed powder according to an embodiment of the present invention, the packing density is 1.7 g / cm ³ to 2.1 g / cm ³ .

In the silicon carbide mixed powder according to an embodiment of the present invention, the first silicon carbide powder is in a beta phase and the second silicon carbide powder is in an alpha phase.

In the silicon carbide mixed powder according to an embodiment of the present invention, the ratio of D ₅₀ of the second silicon carbide powder to D ₅₀ of the first silicon carbide powder is 2 to 40.

In the silicon carbide mixed powder according to an embodiment of the present invention, the volume of the second silicon carbide powder and the volume ratio of the first silicon carbide powder are 1 to 4.

According to the present invention, since the grain growth rate can be controlled in the step of growing the silicon carbide powder, the silicon carbide mixed powder having a high filling density can be produced without separately pulverizing and mixing the silicon carbide fine powder.

Further, since the silicon carbide fine powder is not pulverized and mixed, a high-purity silicon carbide mixed powder can be produced.

Further, since the growth of the silicon carbide powder can be controlled with the optimum particle diameter, the packing density of the mixed powder can be maximized.

1 is a flowchart of a method for producing a silicon carbide mixed powder according to an embodiment of the present invention,
2 is a SEM photograph of a silicon carbide mixed powder produced according to an embodiment of the present invention,
FIG. 3 is a graph showing particle size and volume relation of the silicon carbide mixed powder produced according to an embodiment of the present invention,
4 is a SEM photograph of a silicon carbide mixed powder produced according to another embodiment of the present invention,
FIG. 5 is a graph showing particle size and volume relation of a silicon carbide mixed powder produced according to another embodiment of the present invention,
6 is data obtained by measuring the impurity concentration of the silicon carbide mixed powder produced according to another embodiment of the present invention,
7 is a SEM photograph of a silicon carbide mixed powder produced according to another embodiment of the present invention,
FIG. 8 is a graph showing particle size and volume relation of a silicon carbide mixed powder produced according to another embodiment of the present invention,
9 is an SEM photograph of the silicon carbide mixed powder produced according to Comparative Example 1,
10 is a graph showing the particle size and volume relationship of the silicon carbide mixed powder produced according to Comparative Example 1,
11 is an SEM photograph of the silicon carbide mixed powder produced according to Comparative Example 2,
FIG. 12 is a graph showing particle size and volume relationship of the silicon carbide mixed powder produced according to Comparative Example 2. FIG.

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.

Terms including ordinals, such as first, second, 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 of a method for producing a silicon carbide mixed powder according to an embodiment of the present invention.

Referring to FIG. 1, a method of manufacturing a silicon carbide powder according to an embodiment of the present invention includes: preparing a silicon carbide fine powder (S10); growing a silicon carbide fine powder to form a silicon carbide mixed powder (Step S20).

The step (S10) of preparing silicon carbide fine powder includes a step of mixing a silicon source and a carbon source, and a step of heat-treating the mixed silicon source and carbon source to produce silicon carbide fine powder.

First, in the step of mixing the silicon source and the carbon source, the Si source and the C source are mixed at an appropriate ratio.

The silicon source is one of a variety of materials that can provide silicon. The silicon source may be at least one selected from the group consisting of, for example, fumed silica, silica, silica sol, silica gel, quartz powder and mixtures thereof.

The carbon source may be a solid carbon source or an organic carbon compound. The solid carbon source may be at least one selected from the group consisting of, for example, graphite, carbon black, carbon nanotubes (CNT), fullerene, and mixtures thereof.

The organic carbon compound may be selected from the group consisting of phenol resin, franc resin, xylene resin, polyimide, polyurethane, polyvinyl alcohol, polyacrylonitrile, , Polyvinyl acetate, cellulose, and mixtures thereof.

The silicon source and carbon source may be mixed either wet or dry. The silicon source and the carbon source may be mixed by using, for example, a ball mill, an attrition mill, a 3 roll mill or the like. The mixed powder can be recovered using, for example, a sieve.

The step of producing the silicon carbide fine powder can be divided into a carbonization process and a synthesis process. The carbonization process is performed at, for example, 600 ° C to 1000 ° C, and the synthesis process can be performed for a predetermined time (for example, 3 hours) under the condition of 1300 ° C to 1700 ° C, for example.

The produced silicon carbide fine powder mostly has a beta phase, and the average particle diameter (D ₅₀ ) may be about 0.5 to 20 μm. And preferably has a size of 1 to 10 mu m.

The process of preparing the silicon carbide fine powder as described above is merely an example, and a beta-phase silicon carbide fine powder can be produced by various methods.

In the step S20 of growing a silicon carbide mixed powder having different grain sizes by growing silicon carbide fine powder, a beta-phase silicon carbide powder is heat-treated at a high temperature to grow powder of a desired grain size in a desired ratio.

Specifically, in the step of forming the silicon carbide mixed powder, at least one of a heat treatment temperature, a growth time, a temperature raising rate, and an atmospheric gas is controlled so that grain size of the silicon carbide powder is varied.

At this time, the silicon carbide powder to be grown is grown so that the particle size distribution has two or more peaks.

Generally, when the beta-phase silicon carbide powder is heat-treated at a high temperature, evaporation-condensation occurs due to a high vapor pressure difference between the beta-phase silicon carbide and the alpha phase silicon carbide, and the particles can grow rapidly due to recrystallization.

In one embodiment of the present invention, the powder of silicon carbide is non-uniformly grown to control the particle size distribution to have two or more peaks.

That is, when the particle size distribution has two or more peaks, it means that the silicon carbide fine powder is mixed with the first silicon carbide powder growing to the first size and the second silicon carbide powder growing to the second size.

Specifically, the beta-phase silicon carbide powder grows to a size of about 30 탆 at the high-temperature grain growth, and a certain amount of the β-phase powder grows into the α-phase powder depending on the process temperature. The ingrown alpha phase powder grows from about 100 탆 to 400 탆.

When only a part of the beta-phase silicon carbide powder is grown in the alpha phase and the remainder is controlled to remain in the beta phase, the silicon carbide powder grown in the alpha phase grows into a powder having a relatively large diameter, and the remaining silicon carbide The powder grows into a powder having a relatively small particle diameter.

That is, in the step of growing silicon carbide, the ratio of the desired size of powder can be controlled through the grain growth control.

Therefore, silicon carbide powders having different sizes can be produced without increasing the packing density by crushing and mixing the silicon carbide in order to increase the packing density, so that a powder having a high packing density can be produced.

In addition, since the process of pulverizing and mixing the silicon carbide powders produced is omitted, the risk of introduction of external impurities is eliminated, and high purity silicon carbide powder can be produced.

For example, when the silicon carbide fine powder having a particle size of 1.5 μm is heat-treated for 1 to 10 hours in an argon atmosphere at a temperature of about 1900 ° C. to 2100 ° C., the first silicon carbide powder having an average particle size (D ₅₀ ) , And an average particle size (D ₅₀ ) of 100 to 400 탆 can be produced.

At this time, the second silicon carbide powder has a bimodal structure while growing in an alpha phase. The first silicon carbide powder and the second silicon carbide powder may be agglomerated to grow and may be pulverized if necessary.

That is, when the crystal is grown at 1900 ° C to 2100 ° C, the transition from the beta phase to the alpha phase occurs, so that the rate of transition and the size of grown particles can be controlled by adjusting the heat treatment time.

However, this is an illustrative example, and it is also possible to produce powders in which powders having two or more specific particle size distributions are mixed at an appropriate ratio by controlling at least one of growth temperature, growth time, heating rate and atmosphere gas at the time of grain growth have.

Hereinafter, the present invention will be described in more detail with reference to Examples of the present invention, but the scope of the present invention is not limited by the following Examples.

Example 1 Preparation of Silicon Carbide Mixed Powder

The silicon carbide fine powder having an average particle diameter of 1.5 탆 was heat-treated at a temperature of about 2150 캜 for 150 minutes in an argon atmosphere to prepare a silicon carbide mixed powder. SEM photographs of the silicon carbide powder thus prepared are shown in FIG. 2, and a graph of the particle size and the volume of the silicon carbide mixed powder produced is shown in FIG.

Example 2 Preparation of Silicon Carbide Mixed Powder

The silicon carbide fine powder used in Example 1 was heat-treated at a temperature of about 2150 ° C for 180 minutes in an argon atmosphere to prepare a silicon carbide mixed powder. SEM photographs of the silicon carbide powders were shown in FIG. 4, and a graph showing the particle size and the volume of the silicon carbide mixed powder was shown in FIG. The impurity analysis data is shown in Fig.

Example 3 Preparation of Silicon Carbide Mixed Powder

The silicon carbide fine powder used in Example 1 was heat-treated at a temperature of about 2100 ° C for 100 minutes in a vacuum atmosphere of 10 mbar to prepare a silicon carbide mixed powder. SEM photographs of the silicon carbide powder were shown in FIG. 7, and a graph of the particle size and volume of the silicon carbide mixed powder was shown in FIG.

≪ Comparative Example 1 &

The silicon carbide fine powder used in Example 1 was heat-treated at a temperature of about 2000 캜 for 60 minutes in an argon atmosphere to prepare a silicon carbide mixed powder. SEM photographs of the silicon carbide powders were shown in FIG. 9, and a graph of particle size and volume of the silicon carbide mixed powder was shown in FIG.

≪ Comparative Example 2 &

The silicon carbide fine powder used in Example 1 was heat-treated at a temperature of about 2200 캜 for 300 minutes in an argon atmosphere to prepare a silicon carbide mixed powder. SEM photographs of the silicon carbide powders were shown in FIG. 11, and a graph of the particle size and volume of the silicon carbide mixed powder was shown in FIG.

<Analysis result>

Referring to FIGS. 2 and 3, the silicon carbide mixed powder produced by Example 1 has a second silicon carbide powder 20 having an average particle diameter of about 200 占 퐉 and a first silicon carbide powder 20 having an average particle diameter of about 35 占 퐉 (10) are present at the same time.

It can also be seen that the volume of the second silicon carbide powder 20 is larger than the volume of the first silicon carbide powder 10. This is because the time for silicon carbide to grow is long and sufficient heat energy is supplied.

It can be seen that the first silicon carbide powder has a particle size distribution having a first peak P1 and the second silicon carbide powder has a particle size distribution having a second peak P2. The particle size distribution of the first silicon carbide powder D90 / D10) is 5 or less, and the particle size distribution (D90 / D10) of the second silicon carbide powder is 4 or less.

3, the volume fraction can be calculated by integrating the particle size distribution curve. As a result, it can be understood that the ratio of the volume of the second silicon carbide powder to the volume of the first silicon carbide powder is in the range of 1 to 4. It was also confirmed that the filling density of the silicon carbide mixed powder prepared in Example 1 was 1.78 g / cm ³ .

Referring to FIGS. 4 and 5, the silicon carbide mixed powder produced by Example 2 has a second silicon carbide powder 20 having an average particle diameter of about 250 μm and a first silicon carbide powder having an average particle diameter of about 40 μm (10) are present at the same time.

Further, it can be seen that the volume of the second silicon carbide powder 20 is larger than that of the silicon carbide mixed powder produced by the first embodiment. This is considered to be due to the grain growth for a relatively longer period of time in Example 2. 5, the filling density of the silicon carbide mixed powder was 2.02 g / cm ³ , which was larger than that of Example 1.

Referring to FIG. 6, the silicon carbide mixed powder prepared in Example 2 was found to have a total impurity concentration of 5 ppm or less.

The particle size distribution (D90 / D10) of the first silicon carbide powder was 5 or less and the particle size distribution (D90 / D10) of the second silicon carbide powder was 4 or less.

Referring to FIGS. 7 and 8, the silicon carbide mixed powder produced in Example 3 had a larger volume of the second silicon carbide powder 20 than the mixed powder of silicon carbide produced in Examples 1 and 2 . However, the packing density was 1.95 g / cm &lt; ³ &gt;

9 to 10, it can be seen that Comparative Example 1 does not have a sufficient time required for grain growth control and has a single peak with an average grain size of about 70 μm. Therefore, since the mixed powder could not be obtained, the filling density was also measured to be very low as 1.2 g / cm ³ .

11 and 12, in the case of Comparative Example 2, silicon carbide powder having an average grain size of about 350 mu m was produced by grain growth for too long, and the packing density was also measured as 1.65 g / cm &lt; ³ &gt; .

As a result, it can be seen that the first silicon carbide powder and the second silicon carbide powder having different average particle diameters can be manufactured by appropriately controlling the temperature and time of grain growth.

Further, by controlling the average particle size is so possible to manufacture a mixed powder of different packing density is 1.7 g / cm ³ do not need to mix a silicon carbide powder produced separately, Or more, and the impurity concentration can be remarkably lowered.

Claims (7)

Wherein the first silicon carbide powder and the second silicon carbide powder have different average particle diameters (D ₅₀ )
Silicon carbide mixed powder having a total impurity concentration of 5 ppm or less.
The method according to claim 1,
Filling density of 1.7g / cm ³ to 2.1g / cm ³ of silicon carbide powder mixture.
The method according to claim 1,
Wherein the first silicon carbide powder is a beta phase, and the second silicon carbide powder is an alpha phase.
The method according to claim 1,
Wherein the second average grain size of the silicon carbide powder (D ₅₀₎ and a ratio of 2 to 40 silicon carbide mixed powder of first average grain size of the silicon carbide powder (D _50).
The method according to claim 1,
Wherein the first silicon carbide powder has an average particle diameter (D ₅₀ ) of 10 탆 to 50 탆, and the first silicon carbide powder has an average particle diameter (D ₅₀ ) of 100 탆 to 400 탆.
6. The method of claim 5,
Wherein the first silicon carbide powder has a particle size distribution (D ₉₀ / D ₁₀ ) of 5 or less and the second silicon carbide powder has a particle size distribution (D ₉₀ / D ₁₀ ) of 4 or less.
The method according to claim 1,
Wherein the volume of the second silicon carbide powder and the volume ratio of the first silicon carbide powder are 1 to 4.

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