WO2015068976A1

WO2015068976A1 - Silicon carbide powder and method for preparing silicon carbide

Info

Publication number: WO2015068976A1
Application number: PCT/KR2014/010136
Authority: WO
Inventors: 김규미; 조남태; 류해윤
Original assignee: 오씨아이 주식회사
Priority date: 2013-11-08
Filing date: 2014-10-27
Publication date: 2015-05-14
Also published as: KR101525694B1; KR20150053367A

Abstract

The present invention provides a method for preparing a silicon carbide, the method comprising the steps of: preparing a mixed raw material by mixing solid-phase silicon (Si), solid-phase carbon (C) and alpha-phase silicon carbide (SiC) of solid phase; and heat-treating the mixed raw material. A silicon carbide is obtained by the heat-treatment, and the resulting silicon carbide comprises alpha-phase particles and beta-phase particles and has a bimodal particle size distribution showing a peak in each of the first peak particle size and the second peak particle size.

Description

Silicon Carbide Powder and Silicon Carbide Manufacturing Method

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

Silicon carbide powder is generally manufactured and used by a method known as the Acheson process, which is a silicon carbide in alpha phase by thermochemical reduction at high temperature by electrodischarge by mixing silicon powder and carbon source. It is a manufacturing method of the silicon carbide powder which obtains (SiC) powder.

The silicon carbide powder thus prepared has the advantage that the raw material is inexpensive and advantageous for mass production, while it is difficult to control the size of the particles, for example, the particle size, so that an additional grinding process is needed to control the size of the particles. In order to obtain high-purity powder, it is necessary to carry out additional processes such as performing an additional acid treatment process because it is difficult to control the purity. In addition, it is difficult to synthesize nano-size silicon carbide powder.

One embodiment of the present invention is to provide a method for producing silicon carbide having a uniform particle size distribution can obtain a cost reduction effect.

Another embodiment of the present invention provides a silicon carbide powder prepared by the method for producing silicon carbide showing a particle size distribution having two peak particle sizes at different particle sizes, including alpha phase particles and beta phase particles, Separation of silicon carbide powder, silicon carbide powder composed mainly of spherical beta-phase particles with nano-size average particle size, and silicon carbide powder composed mainly of spherical alpha-phase particles with average particle size of micrometer It is intended to provide each powder.

In one embodiment of the present invention, the raw material prepared by mixing the solid silicon (Si), the solid carbon (C) and the solid alpha phase silicon carbide (SiC) is prepared by heat treatment, alpha phase particles and beta phase particles It includes, and provides a silicon carbide powder having a bimodal distribution showing a peak at each of the first peak particle size and the second peak particle size.

The first peak particle size is in the range of 2 μm to 50 μm, the second peak particle size is in the range of 10 nm to 5 μm, and the first peak particle size is greater than the second peak particle size.

Regarding the total volume of the alpha phase particles, particles having a particle size of 0.5 to 2.5 of the first peak particle size may be 70 to 100% by volume.

Regarding the total volume of the alpha phase particles, particles having a particle size of 0.6 to 1.6 of the first peak particle size may be 75 to 85 volume%.

With respect to the total volume of the beta-phase particles, particles having a particle size of 0.1 to 4.0 of the second peak particle size may be 70 to 100% by weight.

Regarding the total volume of the beta-phase particles, particles having a particle size of 0.4 to 2.3 of the second peak particle size may be 75 to 85 volume%.

The volume ratio of particles having a particle size of 0.5 to 2.5 of the first peak particle size to particles having a particle size of 0.1 to 4.0 of the second peak particle size may be 1: 9 to 9: 1.

The volume ratio of the content of the particles having a particle size of 0.6 to 1.6 of the first peak particle size to the particle size of the particles having a particle size of 0.4 to 2.3 of the second peak particle size may be 1: 9 to 9: 1.

When the particle size of 0.5 to 2.5 of the first peak particle size and the particle size of 0.1 to 4.0 of the second peak particle size are present so as not to overlap each other, the content of the particles having the particle size of 0.5 to 2.5 of the first peak particle size and the second peak The sum of the contents of the particles having a particle size of 0.1 to 4.0 of the particle size may be 70 to 100% by volume of the total volume of the silicon carbide powder particles.

When the particle size of 0.6 to 1.6 of the first peak particle size and the particle size of 0.4 to 2.3 of the second peak particle size are present so as not to overlap each other, the content of the particles having the particle size of 0.6 to 1.6 of the first peak particle size and the second peak are The sum of the contents of the particles having a particle size of 0.4 to 2.3 of the particle size may be 75 to 85% by volume of the total volume of the silicon carbide powder particles.

The alpha-phase particles may be spherical, tetrahedral or plate-shaped silicon carbide having an aspect ratio of 1: 1 to 1: 4.

In another embodiment of the present invention, preparing a mixed raw material by mixing the solid silicon (Si), the solid carbon (C) and the solid alpha phase silicon carbide (SiC); And heat treating the mixed raw material, wherein the silicon carbide is reacted by the heat treatment, and the silicon carbide includes alpha phase particles and beta phase particles, and includes a first peak particle size and a second peak particle size. To prepare a method for producing silicon carbide having a bimodal distribution each showing a peak at.

The above-mentioned silicon carbide powder may be produced by the silicon carbide manufacturing method, and the detailed description of the manufactured silicon carbide powder is as described above.

The solid alpha phase silicon carbide (SiC) may be used a silicon carbide powder having an average particle size of 50nm to 50㎛.

As the solid silicon (Si), a silicon powder having an average particle size of 1 nm to 100 μm may be used.

The solid carbon (C) may be a carbon powder having an average particle size of 0.1nm to 10㎛.

Silicon powder is used as the solid silicon (Si), carbon powder is used as the solid carbon (C), and the average particle size of the silicon powder may be larger than the average particle size of the carbon powder.

The molar ratio of the silicon (Si) and the carbon (C) may be 1: 2 to 3: 1.

The content of the silicon carbide (SiC) in the mixed raw material may be 0.1 to 30 wt%.

The mixed raw material may not include silicon oxide.

The heat treatment may be performed at 900 to 2500 ℃.

The heat treatment may be performed under an inert gas or vacuum atmosphere.

The method may further include grinding the obtained silicon carbide.

Separating the obtained silicon carbide using a sieve (sieve) or classifier may be further included.

The silicon carbide powder of the present invention can produce silicon carbide powder having a particle size distribution in which two peak particles exist at different particle sizes. At this time, one of the two peaks has a particle size of approximately nano size, mainly represented by spherical beta-phase particles, and the other peak has a particle size of approximately micrometer size and mainly represented by spherical alpha-phase particles. That is, one mixed raw material may be used to form particles having spherical shapes but different crystal phases.

It can be used as a raw material for sintering by separating only into silicon carbide powder having a particle size of approximately nano size and forming a peak mainly represented by spherical beta-phase particles, and having a particle size of approximately micro size, and mainly of a spherical alpha phase. It can be separated into only silicon carbide powder which forms the peak represented by the particles, and can be used for applications such as heat dissipating materials, inorganic fillers as structural materials, and the like.

1 is a graph showing the particle size distribution of silicon carbide powders obtained in Example 1 and Comparative Example 1. FIG.

FIG. 2 is an SEM image before pulverization and classification of the powder of silicon carbide prepared in Example 1. FIG.

3 is an SEM image of silicon carbide powder having a size of 1 μm or less as a powder of silicon carbide prepared in Example 1. FIG.

4 is a SEM photograph of silicon carbide powder having a size of 10 μm with powder of silicon carbide prepared in Example 1. FIG.

5 is a SEM photograph of the powder of silicon carbide prepared in Comparative Example 1.

Hereinafter, embodiments of the present invention will be described in detail. However, this is presented as an example, by which the present invention is not limited and the present invention is defined only by the scope of the claims to be described later.

In one embodiment of the present invention, the step of preparing a mixed raw material by mixing the solid silicon (Si), the solid carbon (C) and the solid alpha-phase silicon carbide (SiC); And heat-treating the mixed raw material.

In the silicon carbide production method, the reaction is performed by the heat treatment to obtain silicon carbide. At this time, the obtained silicon carbide contains alpha phase particles and beta phase particles, and has a bimodal distribution showing peaks at the first peak particle size and the second peak particle size, respectively.

The 'particle size' refers to the size of the particle, in this specification means the longest diameter in the particle in one particle. The longest diameter means the longest distance among the distances between the two points defined while meeting the surface of the particle on one straight line among the straight lines passing through the center of gravity of the particle.

Specifically, the particle size defined as described above may be measured by a laser diffraction particle size analyzer (Model: LS I3 320, manufactured by BECKMAN COULTER).

The silicon carbide production method of the present invention can produce silicon carbide powder having a particle size distribution in which two peak particle sizes, that is, a first peak particle size and a second peak particle size, exist at different particle sizes. "Peak particle size" means a particle size corresponding to a peak of a graph, and "first peak particle size" and "second peak particle size" are terms for distinguishing two peak particle sizes.

The first peak particle size is within about 2 μm to about 50 μm, the second peak particle size may be within about 10 nm to about 5 μm, and the first peak particle size is greater than the second peak particle size.

The peak formed around the first peak particle size is represented by the spherical alpha phase particles having a mean particle size of the micrometer size mainly among the silicon carbide particles, and the peak formed around the second peak particle size of the other is Among the silicon carbide particles, they are represented by spherical beta-phase particles having mainly nano-sized particle size. As described above, the silicon carbide manufacturing method may be prepared using one mixed raw material to form particles having a spherical shape but having crystal phases of alpha phase and beta phase which are different crystal phases.

Since each peak present in the particle size distribution of the obtained silicon carbide powder is formed in a sharp shape, the silicon carbide powder formed into uniform particles having a narrow particle size distribution by separating and recovering powder particles distributed within a predetermined range around each peak particle size Can be obtained.

That is, silicon carbide powder mainly formed of beta phase particles as silicon carbide powder having a relatively small average particle size while being formed of uniform particles having a narrow particle size distribution; While being formed into uniform particles having a narrow particle size distribution, silicon carbide powder mainly containing alpha phase particles can be obtained as silicon carbide powder having a relatively large average particle size.

For example, a uniform silicon carbide powder having an average particle size in nano size units and a uniform silicon carbide powder having an average particle size in micrometer size units may be obtained, respectively.

Silicon carbide powder having a relatively small particle size, for example, nano-sized particle size, may be used as a raw material for sintering, and the like, and silicon carbide powder having a relatively large particle size, for example, a micrometer-size particle, may dissipate heat. It can be used for applications such as inorganic fillers as materials and structural materials. In another example, depending on the specific use thereof, the silicon carbide powder of small particle size and large particle size may be used without separating in a mixed state, and may also be used as an inorganic filler as a heat radiation material or a structural material.

In the distribution of silicon carbide powder obtained by the silicon carbide production method, in particular, a peak present at a relatively small particle size of the two peaks may have a sharper shape than other peaks, and is constant before and after the peak present at such a small particle size. It is possible to obtain a uniform silicon carbide powder having a very small particle size distribution while having a small particle size in the recovery by separating the powder particles distributed within the error range.

In general, it is very difficult to produce silicon carbide powder having a relatively small particle size, for example, nano-size particle size, and more difficult to form to have a uniform distribution. The silicon carbide production method is of great significance both economically and commercially in that a uniform distribution of silicon carbide powder having a relatively small particle size, for example, a nano-sized particle size, can be obtained.

In one embodiment, in the silicon carbide powder prepared as described above, particles having a particle size of 0.5 to 2.5 of the first peak particle size with respect to the total content of the alpha phase particles may be 70 to 100% by volume. For example, the particles having a particle size of 0.6 to 1.6 of the first peak particle size may be 75 to 85 vol% based on the total content of the alpha phase particles of the silicon carbide powder prepared according to the present invention. Silicon carbide powder having such a distribution means that the first peak is sharply formed, which also means that the powder forming the first peak, that is, the alpha phase particles are formed to have a uniform particle size.

In another embodiment, in the silicon carbide powder prepared as described above, particles having a particle size of 0.1 to 4.0 of the second peak particle size with respect to the total content of the beta phase particles may be 70 to 100% by volume. For example, the particles having a particle size of 0.4 to 2.3 of the second peak particle size may be 75 to 85 vol% based on the total content of the beta phase particles of the silicon carbide powder prepared according to the present invention. Silicon carbide powder having such a distribution means that the second peak is sharply formed, which also means that the powder forming the second peak, that is, the beta phase particles, is formed to have a uniform particle size.

In another embodiment, in the silicon carbide powder prepared as above, the volume ratio of the content of particles having a particle size of 0.5 to 2.5 of the first peak particle size to the particle size of particles having a particle size of 0.1 to 4.0 of the second peak particle size May be from 1: 9 to 9: 1. Specifically, the volume ratio of particles having a particle size of 0.6 to 1.6 of the first peak particle size and particles having a particle size of 0.4 to 2.3 of the second peak particle size may be 1: 9 to 9: 1.

In another embodiment, in the silicon carbide powder prepared as above, when the particle size of 0.5 to 2.5 of the first peak particle size and 0.1 to 4.0 of the second peak particle size are present so as not to overlap each other, the first peak The sum of the content of the particles having a particle size of 0.5 to 2.5 and the content of the particles having a particle size of 0.1 to 4.0 of the second peak particle size may be 70 to 100% by volume of the total volume of the silicon carbide powder particles. For example, the sum of the content of the particles having a particle size of 0.6 to 1.6 of the first peak particle size and the content of the particles having a particle size of 0.4 to 2.3 of the second peak particle size is 75 to 85 of the total volume of the silicon carbide powder particles. Volume%.

The silicon carbide production method is a method in which the direct carbonization method of mixing SiC as a raw material is applied, and a method of effectively obtaining uniform silicon carbide powder with a small particle size.

Since the silicon carbide manufacturing method is a method of applying the direct carbonization method, the recovery rate is much higher than that of the low carbon recovery method. However, in the case of the direct carbonization method, there is a disadvantage in that the particle size distribution of the obtained silicon carbide is very wide, and the method of manufacturing the silicon carbide solves this problem and can obtain a uniform silicon carbide having a high recovery rate and a narrow particle size distribution at the same time. to be. For example, the silicon carbide manufacturing method may have a recovery of about 99 wt% or more.

Solid silicon (Si) in the mixed raw material may be a silicon powder having an average particle size of about 1nm to about 100㎛. The larger the particle size of the silicon powder to be used, the higher the heat treatment temperature and the longer the time, so that the silicon powder having a size in the above range can be suitably used in consideration of reactivity, heat treatment process conditions, economical efficiency, and the like.

Specifically, carbon (C) in the mixed raw material may be carbon black, graphite powder, or the like, and for example, carbon powder having an average particle size of about 0.1 nm to about 10 μm may be used. For example, the average particle size of the silicon powder in the mixed raw material may be larger than the average particle size of the carbon powder.

The molar ratio of the silicon (Si) and the carbon (C) in the mixed raw material may be about 1: 2 to about 3: 1. By blending the raw materials to have the molar ratio, the production of unreacted carbon and unreacted silicon can be minimized to improve yield.

The alpha-phase silicon carbide (SiC) may be used a silicon carbide powder having an average particle size of about 50nm to about 50㎛.

As described above, the silicon carbide manufacturing method uses the alpha-phase silicon carbide (SiC) together with silicon (Si) and carbon (C) as a raw material, and the alpha-phase silicon carbide (SiC) acts as a seed (seed) It is possible to form a particle size distribution with two peaks as described above.

In more detail about this, when silicon (Si) is mixed with carbon (C) and silicon carbide (SiC) with silicon (Si) rather than oxide, and heat treated, the heat generated by the exothermic reaction is smoothly reacted. It is not diffused and the local heat generation becomes severe, resulting in the formation of very unstable SiC gas. These unstable SiC gases form stable beta-phase SiC crystals, some of which are deposited on nearby alpha-phase SiC.

The stable beta-phase SiC crystals are particles that are distributed at peaks present on the lower particle size side of the above-described silicon carbide particle size distribution, and the alpha-phase SiC crystals formed by depositing an unstable SiC gas on the alpha-phase SiC crystals have the aforementioned silicon carbide particle size distribution It becomes the particle | grains distributed in the peak which exists in the larger particle size side of.

Since the particles formed by the beta-phase SiC crystals are usually spherical, the particles distributed at the peak present on the lower particle size side of the silicon carbide particle size distribution described above have a spherical beta-shaped SiC crystal structure.

The particles formed by the alpha-phase SiC crystals are usually not spherical, but the particles distributed at the peaks present on the larger particle size side of the silicon carbide particle size distribution described above have a spherical alpha-phase SiC crystal structure. This is because, as can be seen from the above-described production mechanism, the SiC gas which is unstable in the alpha phase SiC crystal was formed by deposition. Accordingly, the silicon carbide production method has the advantage that the alpha phase particles can obtain spherical silicon carbide particles while having SiC crystals. The term 'spherical' in the present invention encompasses not only the case where the cross section has a perfect circle but also the case where it has an ellipse, that is, usually seen in the form of a sphere. In contrast, the alpha phase particles according to the present invention may have a tetrahedron or an aspect ratio of 1: 1 to 1: 4. Silicon carbide powder having a spherical, tetrahedron or plate-shaped particle shape having an aspect ratio of 1: 1 to 1: 4 or less may have a higher packing density than an amorphous silicon carbide powder prepared through a grinding process. In particular, since the beta-phase particles of the above type have excellent sintering properties, and the alpha-phase particles have excellent heat dissipation properties, the silicon carbide powder or alpha-phase particles and beta containing mainly the alpha-phase particles obtained according to the present invention. When the heat dissipation product is manufactured from silicon carbide powder mixed with phase particles, heat dissipation characteristics of the heat dissipation product may be further improved.

On the other hand, for example, if the mixed raw material includes silicon oxides other than silicon (Si), carbon monoxide (CO) may be produced, and carbon monoxide (CO) may provide a thermal diffusion path so that no local exothermic sites are formed. As a result, as described above, an unstable SiC gas cannot be produced. Therefore, in this case, it becomes impossible to obtain silicon carbide in which two peaks exist in the particle size distribution.

Therefore, the silicon carbide production method does not include silicon oxide in the mixed raw material.

The content of the silicon carbide (SiC) in the mixed raw material may be about 0.1 to about 30% by weight. According to the content of silicon carbide (SiC) contained in the mixed raw material, the peak shape of the obtained silicon carbide particle size distribution can be adjusted.

The meaning of adjusting the peak shape of the obtained silicon carbide means, for example, the content ratio of the small particle size silicon carbide particles to the large particle size silicon carbide particles, the degree to which each peak is sharp, that is, the uniformity of the particles distributed near each peak. It may mean that the sex and the like are controlled.

Heat treatment in the silicon carbide manufacturing method may be performed at about 900 to about 2500 ℃, specifically about 1000 to about 1950 ℃. Since the heat treatment temperature is relatively low, the silicon carbide manufacturing method is cost-effective in terms of economy.

In general, in the heat treatment temperature range, the crystal type of silicon carbide obtained is formed in a beta-phase low-temperature stable phase, whereas the crystal type of silicon carbide obtained by the silicon carbide production method, as described above, The low temperature stable phase of the beta phase is formed together.

As described above, of the two peaks present in the particle size distribution of the silicon carbide powder obtained by the silicon carbide production method, the particles present near the large particle size peak are formed as the high temperature stable phase of the alpha phase, and are located near the low particle size peak. Particles present in the tendency to be formed in the beta-phase low temperature stable phase.

The heat treatment may be performed under an inert gas such as argon, hydrogen, nitrogen, or a vacuum atmosphere.

The silicon carbide production method has an advantage of shortening the heat treatment time. For example, the heat treatment time may be about 1 minute to about 300 minutes.

Since the silicon carbide obtained by the silicon carbide production method can be obtained in the form of aggregated particles, it can be ground by milling to separate such aggregated particles.

Milling methods are known as ball mills, planetary mills, attrition mills, spec mills, beads mills, jet mills, etc. The method may be used without limitation.

As such, the silicon carbide manufacturing method may further include grinding the obtained silicon carbide.

Containers such as jars used for grinding, milling media, etc. may be made of SiC material.

In addition, the pulverized particles may be separated by using a sieve or a classifier to separate the particles about the particle size of each peak forming the two peaks. The sieve may be metal sieve or poly sieve, and the classifier may be a dry classifier or a wet classifier.

As such, the silicon carbide production method may further include separating the silicon carbide obtained by using a sieve or classifier.

In another embodiment of the present invention, the raw material prepared by mixing the solid silicon (Si), solid carbon (C) and solid phase alpha carbide (SiC) is prepared by heat treatment, alpha phase particles and beta phase particles It includes, and provides a silicon carbide powder having a bimodal distribution showing a peak at each of the first peak particle size and the second peak particle size.

The silicon carbide powder is prepared by the above-described method for producing silicon carbide powder, and the detailed description is as described above.

The silicon carbide powder has a particle size distribution in which two peak particle sizes, that is, a first peak particle size and a second peak particle size, exist at different particle sizes. The first peak particle size and the second peak particle size mean particle sizes corresponding to peaks.

The first peak particle size may be present in the range of 2 μm to 50 μm, the second peak particle size may exist in the range of 10 nm to 5 μm, and the first peak particle size may be larger than the second peak particle size.

In one embodiment, in the silicon carbide powder, the particles having a particle size of 0.5 to 2.5 of the first peak particle size with respect to the total content of the alpha phase particles may be 70 to 100% by volume. For example, the particles having a particle size of 0.6 to 1.6 of the first peak particle size may be 75 to 85 vol% based on the total content of the alpha phase particles of the silicon carbide powder prepared according to the present invention.

In another embodiment, in the silicon carbide powder, the particles having a particle size of 0.1 to 4.0 of the second peak particle size with respect to the total content of the beta-phase particles may be 70 to 100% by volume. For example, the particles having a particle size of 0.4 to 2.3 of the second peak particle size may be 75 to 85 vol% based on the total content of the beta phase particles of the silicon carbide powder prepared according to the present invention.

In another embodiment, in the silicon carbide powder, the volume ratio of the content of particles having a particle size of 0.5 to 2.5 of the first peak particle size to the particle size of the particles having a particle size of 0.1 to 4.0 of the second peak particle size is 1: 9. To 9: 1.

In another embodiment, in the silicon carbide powder, when the particle size of 0.5 to 2.5 of the first peak particle size and 0.1 to 4.0 of the second peak particle size are present so as not to overlap each other, 0.5 to of the first peak particle size The sum of the content of the particles having a particle size of 2.5 and the content of the particles having a particle size of 0.1 to 4.0 of the second peak particle size may be 70 to 100% by volume of the total volume of the silicon carbide powder particles.

In another embodiment, in the silicon carbide powder, when the particle size of 0.5 to 2.5 of the first peak particle size and 0.1 to 4.0 of the second peak particle size are present so as not to overlap each other, 0.5 to of the first peak particle size The sum of the content of the particles having a particle size of 2.5 and the content of the particles having a particle size of 0.1 to 4.0 of the second peak particle size may be 75 to 85% by volume of the total volume of the silicon carbide powder particles.

The silicon carbide powder has an advantage of including spherical or tetrahedral or plate-shaped silicon carbide particles having an aspect ratio of 1: 1 to 1: 4 while having an alpha phase SiC crystal.

The following presents specific embodiments of the present invention. However, the embodiments described below are merely for illustrating or explaining the present invention in detail, and thus the present invention is not limited thereto.

(실시예)(Example)

실시예 1Example 1

Si powder having an average particle size of 50 μm, carbon black having an average particle size of 30 nm, and silicon carbide powder having an average particle size of 10 μm were prepared. Si powder, carbon black, and silicon carbide seed thus prepared were mixed to prepare a mixed raw material. Here, the mixing molar ratio of the Si powder and the carbon black was mixed at 1.15: 1, and the silicon carbide seed was added so as to be 15 wt% in the total content of the mixed raw materials and mixed uniformly. The mixed raw material powder thus mixed was put into a graphite crucible and heat-treated at 1700 ° C. for 2 hours under an argon atmosphere to obtain silicon carbide powder.

The obtained silicon carbide powder was observed to have some agglomeration formed and pulverized by ball milling at 350 rpm for 15 hours to separate this agglomeration. The silicon carbide powder separated by ball milling was recovered through a sieve, and the recovery rate of the powder thus recovered was 99 wt%.

실시예 2Example 2

Si powder having an average particle size of 30 μm, carbon black having an average particle size of 30 nm, and alpha phase silicon carbide powder having an average particle size of 1 μm were prepared. Si powder, carbon black, and silicon carbide seed thus prepared were mixed to prepare a mixed raw material. Here, the molar ratio of Si powder and carbon black in the raw material is 1: 1.25, and silicon carbide seed is added so as to be 5 wt% of the total content of the mixed raw material. The mixed raw powder is mixed in a graphite crucible for 1 hour at 1200 ° C. Heat treatment under argon atmosphere afforded silicon carbide powder.

실시예 3Example 3

Si powder having an average particle size of 100 μm, carbon black having an average particle size of 30 nm, and silicon carbide powder having an average particle size of 30 μm were prepared. Si powder, carbon black, and silicon carbide seed thus prepared were mixed to prepare a mixed raw material. Here, the Si powder and carbon black were mixed in a mixing molar ratio of 2: 1, and the silicon carbide seed was added to be 30 wt% in the total content of the mixed raw materials and mixed uniformly. The mixed raw material powder thus mixed was put into a graphite crucible and heat-treated at 1900 ° C. for 5 hours in an argon atmosphere to obtain silicon carbide powder.

비교예 1Comparative Example 1

Silicon carbide powder was prepared in the same manner as in Example 1 except that no silicon carbide seed was added.

실험예 1: 입도 분포Experimental Example 1: Particle Size Distribution

The particle size of the silicon carbide powder obtained in Examples 1-3 and Comparative Example 1 was measured using LS 13 320, BECKMAN COULTER. The distribution is shown in FIG. 1 graphically, and the first peak particle size and the second peak particle size (including when one peak appears) appearing in the graph peaks are shown in Table 1 below.

Table 1

division	First peak particle size	Second peak particle size
Example 1	1 um	10 um
Example 2	50 nm	2 um
Example 3	5 um	30 um
Comparative Example 1	-	10 um

Referring to Figure 1 and Table 1, it can be seen that there are two peaks in the particle size distribution of the silicon carbide powder according to Examples 1 to 3.

On the other hand, in the particle size distribution of the silicon carbide powder according to Comparative Example 1, it can be seen that a single peak appears around 10 μm on average.

In addition, in Examples 1-3, the content of the particles having a particle size of 0.6 to 1.6 of the first peak particle size was measured with respect to the total volume of the prepared particles, and the results are shown in Table 2 below. In addition, in Example 1-3, the content of the particles having a particle size of 0.4 to 2.3 of the second peak particle size with respect to the total volume of the prepared particles was measured, the results are shown in Table 2 below.

TABLE 2

division	Content [volume%] of particles having a particle size of 0.6 to 1.6 of the first peak particle size	Content of particles having a particle size of 0.4 to 2.3 of the second peak particle size [% by volume]	Volume ratio
Example 1	8	72	1: 9
Example 2	40	40	1: 1
Example 3	67	13	5: 1

As shown in FIG. 1, it can be seen that the particle size distribution represented by the silicon carbide powder prepared in Comparative Example 1 is nonuniformly formed through wide distribution. Specifically, it can be seen that the powder of silicon carbide obtained in Comparative Example 1, although having an average particle size in the vicinity of about 10 um, only appears as a single peak and has a very wide particle size distribution over a particle size range of 0.1 um to 250 um. Can be.

In contrast, the particle size distribution of the silicon carbide powder prepared in Example 1 shows a bimodal distribution graph in which peaks are present at particle sizes of 1 μm or less and at particle sizes of about 10 μm, respectively, and each peak forms a sharp curve. It can be seen that the particle size is uniformly formed before and after each peak. Thus, beta-phase particles having a particle size of about 1 micrometer or less, the size of which can be used for sintering by the method of Example 1, and alpha-particles having a particle size of about 10 micrometers, which can be used as a heat dissipation material, are simultaneously Could get In this case, the sum of the content of the particles having a particle size of 0.6 to 1.6 of the first peak particle size and the particles having a particle size of 0.4 to 2.3 of the second peak particle size is about 80% by volume based on the total volume of the silicon carbide powder prepared. Able to know.

In addition, as shown in Table 1, the particle size distribution diagram of the silicon carbide powders prepared in Examples 2 and 3 has a bimodal distribution in which peaks appear at two peak particle sizes, and each of these graphs is also shown in the example of FIG. It has a tendency similar to the particle size distribution of the silicon carbide powder prepared in step 1. From the results in Table 2, at least about 80% by volume of the total volume of the silicon carbide powder prepared is particles having a particle size of 0.6 to 1.6 of the first peak particle size and particles having a particle size of 0.4 to 2.3 of the second peak particle size. It can be seen that consists of. In addition, also in Examples 2 and 3, it can be seen that the particle size distribution formed a sharp curve of the peak at each of the two peak particle size, so that the particle size was uniformly formed before and after each peak.

In Examples 1 to 3, by producing a silicon carbide powder using a mixed raw material containing silicon carbide seeds, it is possible to uniformly control the size of the silicon carbide powder, and to have a bimodal distribution having a uniform particle size distribution It could be confirmed that silicon powder was prepared.

3 is an SEM image of silicon carbide powder having a size of 1 μm or less as a powder of silicon carbide prepared in Example 1. FIG. Referring to FIG. 3, it can be seen that particles having beta-shaped spherical crystals are formed as silicon carbide powder prepared according to the production method of the present invention.

4 is a SEM photograph of silicon carbide powder having a size of 10 μm with powder of silicon carbide prepared in Example 1. FIG. In FIG. 4, particles having an alpha phase spherical crystal can be identified.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of the invention.

Claims

It is manufactured by heat-treating a mixed raw material prepared by mixing solid silicon (Si), solid carbon (C) and solid alpha phase silicon carbide (SiC),

Alpha and beta particles,

Silicon carbide powder having a bimodal distribution each showing a peak at a first peak particle size and a second peak particle size.
The method of claim 1,

The first peak particle size is within 2 μm to 50 μm, the second peak particle size is within 10 nm to 5 μm, and the first peak particle size is greater than the second peak particle size

Silicon carbide powder.
The method of claim 1,

Regarding the total volume of the alpha phase particles, particles having a particle size of 0.5 to 2.5 of the first peak particle size are 70 to 100% by volume.

Silicon carbide powder.
The method of claim 1,

75 to 85% by volume of particles having a particle size of 0.6 to 1.6 of the first peak particle size relative to the total volume of the alpha phase particles.

Silicon carbide powder.
The method of claim 1,

70 to 100% by weight of particles having a particle size of 0.1 to 4.0 of the second peak particle size relative to the total volume of the beta-phase particles.

Silicon carbide powder.
The method of claim 1,

75 to 85% by volume of particles having a particle size of 0.4 to 2.3 of the second peak particle size relative to the total volume of the beta-phase particles.

Silicon carbide powder.
The method of claim 1,

The volume ratio of particles having a particle size of 0.5 to 2.5 of the first peak particle size to particles having a particle size of 0.1 to 4.0 of the second peak particle size is 1: 9 to 9: 1.

Silicon carbide powder.
The method of claim 1,

The volume ratio of particles having a particle size of 0.6 to 1.6 of the first peak particle size to particles having a particle size of 0.4 to 2.3 of the second peak particle size is 1: 9 to 9: 1.

Silicon carbide powder.
The method of claim 1,

When the particle size of 0.5 to 2.5 of the first peak particle size and the particle size of 0.1 to 4.0 of the second peak particle size are present so as not to overlap each other, the content of the particles having the particle size of 0.5 to 2.5 of the first peak particle size and the second peak The sum of the contents of the particles having a particle size of 0.1 to 4.0 of the particle size is 70 to 100% by volume of the total volume of the silicon carbide powder particles.

Silicon carbide powder.
The method of claim 1,

When the particle size of 0.6 to 1.6 of the first peak particle size and the particle size of 0.4 to 2.3 of the second peak particle size are present so as not to overlap each other, the content of the particles having the particle size of 0.6 to 1.6 of the first peak particle size and the second peak are The sum of the contents of the particles having a particle size of 0.4 to 2.3 of the particle size is 75 to 85% by volume of the total volume of the silicon carbide powder particles.

Silicon carbide powder.
The method of claim 1,

The alpha-phase particles are spherical, tetrahedral or plate-shaped silicon carbide particles with an aspect ratio of 1: 1 to 1: 4.

Silicon carbide powder.
Preparing a mixed raw material by mixing solid silicon (Si), solid carbon (C), and solid alpha phase silicon carbide (SiC); And

Heat treating the mixed raw material;

Including,

By the heat treatment, silicon carbide is obtained,

The obtained silicon carbide contains alpha phase particles and beta phase particles, and has a bimodal distribution showing peaks at the first peak particle size and the second peak particle size, respectively.

Silicon Carbide Manufacturing Method.
The method of claim 12,

The first peak particle size is within 2 μm to 50 μm, the second peak particle size is within a range of 10 nm to 5 μm, and the first peak particle size is greater than the second peak particle size

Silicon Carbide Manufacturing Method.
The method of claim 12,

70 to 100% by volume of particles having a particle size of 0.6 to 1.6 of the first peak particle size relative to the total volume of the alpha phase particles

Silicon Carbide Manufacturing Method.
The method of claim 12,

Regarding the total volume of the beta-phase particles, particles having a particle size of 0.4 to 2.3 of the second peak particle size are 70 to 100% by volume.

Silicon Carbide Manufacturing Method.
The method of claim 12,

The volume ratio of particles having a particle size of 0.5 to 2.5 of the first peak particle size to particles having a particle size of 0.1 to 4.0 of the second peak particle size is 1: 9 to 9: 1.

Silicon Carbide Manufacturing Method.
The method of claim 12,

When the particle size of 0.5 to 2.5 of the first peak particle size and the particle size of 0.1 to 4.0 of the second peak particle size are present so as not to overlap each other, the content of the particles having the particle size of 0.5 to 2.5 of the first peak particle size and the second peak The sum of the contents of the particles having a particle size of 0.1 to 4.0 of the particle size is 70 to 100% by volume of the total volume of the silicon carbide powder particles.

Silicon Carbide Manufacturing Method.
The method of claim 12,

The solid alpha phase silicon carbide (SiC) is a silicon carbide powder having an average particle size of 50nm to 50㎛

Silicon Carbide Manufacturing Method.
The method of claim 12,

The solid silicon (Si) using a silicon powder having an average particle size of 1nm to 100㎛

Silicon Carbide Manufacturing Method.
The method of claim 12,

The solid carbon (C) is a carbon powder having an average particle size of 0.1nm to 10㎛

Silicon Carbide Manufacturing Method.
The method of claim 12,

Silicon powder is used as the solid silicon (Si), carbon powder is used as the solid carbon (C), and the average particle size of the silicon powder is larger than the average particle size of the carbon powder.

Silicon Carbide Manufacturing Method.
The method of claim 12,

Molar ratio of the silicon (Si) and the carbon (C) is 1: 2 to 3: 1

Silicon Carbide Manufacturing Method.
The method of claim 12,

The content of the silicon carbide (SiC) in the mixed raw material is 0.1 to 30 wt%

Silicon Carbide Manufacturing Method.
The method of claim 12,

The mixed raw material does not contain silicon oxide

Silicon Carbide Manufacturing Method.
The method of claim 12,

The heat treatment is carried out at 900 to 2500 ℃

Silicon Carbide Manufacturing Method.