KR20210027947A - PREPARATION METHOD OF HIGH PURITY SiC POWDER - Google Patents

Abstract

A manufacturing method of SiC powder according to an embodiment can not only solve environmental problems by using waste SiC, but also can reduce costs, thereby providing high-purity SiC powder with high uniformity and improved yield and productivity.

Description

Manufacturing method of high purity SiC powder {PREPARATION METHOD OF HIGH PURITY SiC POWDER}

The present invention relates to a method for producing high purity silicon carbide (SiC) powder using SiC waste.

Silicon carbide (SiC) is excellent in heat resistance and mechanical strength, has strong properties against radiation, and has the advantage of being able to produce even large-diameter substrates. In addition, silicon carbide has excellent physical strength and chemical resistance, has a large energy band gap, and a high saturation drift rate and breakdown pressure of electrons. Therefore, it is widely used not only for semiconductor devices requiring high power, high efficiency, high breakdown voltage, and large capacity, but also for abrasives, bearings, refractory plates, and the like.

Silicon carbide is produced through various methods such as heat treatment or energization of carbon raw materials such as silicon carbide waste. Conventional methods include Acheson method, reactive sintering method, atmospheric sintering method, or chemical vapor deposition (CVD) method. However, these methods have a problem that carbon raw materials remain, and these residues act as impurities and have a disadvantage in that thermal, electrical, and mechanical properties of silicon carbide may be deteriorated.

For example, in Japanese Patent Laid-Open No. 2002-326876, in order to polymerize or cross-link a silicon source and a carbon source, a silicon carbide precursor that has undergone a heat treatment process is reacted at a high temperature under an inert gas condition such as argon (Ar). Disclosed is a method of manufacturing. However, since such a process is heat-treated at a high temperature of 1,800°C to 2,100°C under vacuum or inert gas conditions, the manufacturing cost is high, and the size of the powder is not uniform.

Moreover, wafers used in the solar cell and semiconductor industry are manufactured by growing from silicon ingots in a crucible made of graphite, etc., and in the manufacturing process, not only waste slurry containing silicon carbide, but also silicon carbide waste adsorbed on the inner wall of the crucible is generated in a significant amount. do. However, up to now, such waste has been landfilled to cause environmental problems, and large disposal costs have been incurred.

Japanese Patent Laid-Open No. 2002-326876

Accordingly, the embodiment aims to solve environmental problems by utilizing silicon carbide (SiC) waste as a resource, as well as to reduce cost, as well as provide a method of manufacturing a high purity SiC powder with high yield and high productivity, and high uniformity.

The method of manufacturing SiC powder according to the embodiment can solve environmental problems and reduce costs by recycling SiC waste (hereinafter, waste SiC). Further, by using the above manufacturing method, high purity SiC powder having high yield and high productivity and excellent uniformity can be obtained.

The method of manufacturing SiC powder according to the embodiment enables environmental problems and cost reduction by recycling SiC waste (hereinafter, waste SiC). Further, by using the above manufacturing method, high purity SiC powder having high yield and high productivity and excellent uniformity can be obtained.

Hereinafter, the invention will be described in detail through embodiments. The implementation is not limited to the content disclosed below, and may be modified in various forms unless the gist of the invention is changed.

In the present specification, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless otherwise stated.

All numbers and expressions indicating amounts of components, reaction conditions, and the like described herein are to be understood as being modified by the term "about" in all cases unless otherwise specified.

A method of manufacturing SiC powder according to an embodiment comprises the steps of cutting waste SiC; Removing graphite from the cut waste SiC; Pulverizing the waste SiC from which the graphite has been removed; Removing the iron (Fe) component from the pulverized waste SiC; And cleaning the waste SiC from which the iron component has been removed.

The raw material used in the method of manufacturing SiC powder according to an embodiment may be waste SiC.

The waste SiC may be a SiC material that is not usable due to product defects among SiC coating materials that are used when growing a SiC single crystal ingot or manufactured by a chemical vapor deposition (CVD) method. Since SiC is an expensive material, when SiC powder is manufactured using such waste SiC, there is an effect of cost reduction and environmental protection.

According to one embodiment, the waste SiC is at least one selected from the group consisting of Li, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn and Mo Impurities may be included in an amount of 0.1 ppm to 15 ppm. For example, the impurities are 0.1 to 13 ppm, 0.3 to 12 ppm, 0.5 to 12 ppm, 0.5 to 10 ppm, 0.5 to 8 ppm, 0.8 to 10 ppm, 1 to 10 ppm, 1 to 8 ppm, 1 to 6 ppm, 0.1 to 5 ppm, 0.5 ppm to 4 ppm, 0.1 ppm to 3 ppm, 0.5 ppm to 3 ppm, 0.5 ppm to 2 ppm.

According to one embodiment, the waste SiC may contain graphite in an amount of 50% by weight or less. For example, the waste SiC may contain graphite in an amount of 45% by weight or less and 40% by weight or less. Specifically, 1 wt% to 50 wt%, 5 wt% to 45 wt%, 5 wt% to 40 wt%, 10 wt% to 40 wt%, 10 wt% to 35 wt%, 10 wt% to 30 wt% Or it may contain 10% by weight to 20% by weight.

Steps to cut waste SiC

According to one embodiment, the waste SiC may be cut and used.

The cutting can be cut to a desired length using a bar cutting machine.

According to one embodiment, the waste SiC may be cut into 0.1 mm to 150 mm. For example, the waste SiC 0.1 mm to 130 mm, 0.1 mm to 100 mm, 0.5 mm to 80 mm, 1 mm to 80 mm, 5 mm to 70 mm, 10 mm to 70 mm or 20 mm to 50 mm Can be cut.

When cutting the waste SiC, it is possible to efficiently crush the waste SiC in a subsequent process. In addition, it is necessary to cut into a constant and appropriate size for smooth graphite removal in a subsequent process.

Steps to remove graphite from waste SiC

A method of manufacturing SiC powder according to an embodiment includes the step of removing graphite from the cut waste SiC.

According to an embodiment, the step of removing graphite may be performed by shot blasting.

In the graphite removal step, a steel cut wire shot may be used, and the steel cut wire shot may be carbon steel, stainless steel, aluminum, zinc, nickel, copper, or It may be made of an alloy, but is not limited thereto.

According to one embodiment, the diameter of the steel cut wire short may be 0.2 mm to 0.8 mm or 0.4 mm to 0.6 mm.

In addition, the graphite removal step may be performed under conditions of 1,000 RPM to 5,000 RPM and 1 KPa to 1 MPa.

More specifically, the graphite removal step may be performed for 80 to 130 minutes at a rotation speed of 60 Hz (3,600 RPM). For example, it may be performed for 90 minutes to 120 minutes or 100 minutes to 110 minutes at a rotation speed of 60 Hz. In addition, if necessary, shot blasting may be performed 2 to 4 times under the above conditions.

If the above range is satisfied, graphite can be more efficiently removed, and the purity of the finally produced SiC can be improved.

[Oxidation step]

The step of removing the graphite may further include the step of oxidizing the waste SiC.

The oxidation step may efficiently remove graphite by oxidizing the graphite adsorbed on the waste SiC (refer to the reaction equation below).

[Reaction Scheme]

C(s) + O ₂ (g) -> CO ₂ (g)

According to one embodiment, the oxidation step may be performed before the shot blasting process. If the oxidation step before the shot blasting process is performed first, graphite can be more easily separated and removed from waste SiC.

According to one embodiment, the oxidation step may be performed after the shot blasting. When the oxidation step is performed after the shot blasting process, fine graphite remaining after the shot blasting process may be removed to further improve the graphite removal rate.

It is important to maintain a constant temperature in the oxidation step. For example, the oxidation step may be performed at 1,200°C or less, 100 to 1,200°C, or 500 to 1,200°C. If it exceeds the above temperature range, since oxygen and SiC react to form silicon oxide (SiO ₂ ), the above temperature range should be noted.

The oxidation step may include a first oxidation step and a second oxidation step.

The first oxidation step is an oxidation step performed before the shot blasting process, and may be performed at 1,200°C or less, 100 to 1,200°C, or 500 to 1,200°C for 5 to 50 hours, 5 to 30 hours, or 9 to 30 hours. .

In addition, the second oxidation step is an oxidation step performed after the shot blasting process, which may be performed at 1,200°C or less, 100 to 1,200°C or 500 to 1,200°C for 5 to 20 hours, 5 to 15 hours, or 6 to 15 hours. I can.

According to one embodiment, the graphite removal step may include a first oxidation step, a shot blasting step, and a second oxidation step.

[??Ching stage]

The graphite removal step may further include a quenching step.

Specifically, in the graphite removal step, after the oxidation step is completed, quenching of rapidly cooling waste SiC may be performed.

In the quenching step, thermal stress is imparted by cooling the waste SiC of high temperature oxidized at 1,200°C or less, 100 to 1,200°C, or 500 to 1,200°C, and thereby may be pulverized.

At this time, cooling may be performed using a refrigerant or a solvent. For example, the quenching step may be performed in one or more solvents selected from the group consisting of tap water, distilled water, deionized water, methanol and ethanol. In this case, the solvent may be used by mixing with one or more refrigerants selected from the group consisting of dry ice, ice pack, and ice. The ice pack may be a commercial product containing a super absorbent polymer (SAP). In addition, in order to keep the temperature of the cooling water constant, a cooling device using a heat exchange device may be used.

The quenching step may be performed at 0 to 60°C or 0 to 50°C.

The quenching step may include a first quenching step and a second quenching step.

The first quenching step and the second quenching step may be performed immediately after the first oxidation step and the second oxidation step, respectively.

According to one embodiment, the graphite removal step may include a first oxidation step, a first quenching step, a shot blasting step, a second oxidation step, and a second quenching step.

Specifically, in the graphite removal step, the cut waste SiC may be primarily oxidized (first oxidation step) to separate the graphite adsorbed on the waste SiC and pulverize the waste SiC by separating the graphite adsorbed on the waste SiC (first quenching step). ). The first quenching step may be performed at 15 to 50°C or 20 to 50°C for 30 seconds or more to less than 10 minutes or 1 minute to less than 10 minutes. The larger the temperature deviation during ching, the finer the size of the pulverized waste SiC becomes, but if it is pulverized too finely, it is difficult to put it into the shot blaster and the shot blasting process does not proceed, so it should be performed within the above temperature range. In addition, since SiC has a high heat transfer coefficient, the quenching time should not exceed 10 minutes.

After completing the first quenching step, the waste SiC is dried and then put into a shot blaster, and a second oxidation step may be performed. The second oxidation step is the same as described above, and the graphite adsorbed on the waste SiC may be completely removed through the second oxidation.

The waste SiC from which the graphite has been completely removed can be pulverized by performing quenching again (second quenching step). The second quenching step may be performed at 0 to 15°C or 0 to 10°C for 1 minute to 10 minutes or 1 minute to 3 minutes. Since the waste SiC of the above step is in a state in which most of the graphite has been removed, pulverization may occur to a fine size, and may be performed at a lower temperature than in the first quenching step. At this time, if the temperature of the solvent is kept low by using a refrigerant such as dry ice as an additive, pulverization efficiency can be further increased due to a continuous crushing effect.

According to one embodiment, the graphite removal step further includes a step of confirming whether the graphite has been removed using an LED lamp in each step, such as after the first quenching step, after the second quenching step, or after shot blasting. You can do it.

In addition, in the step of removing the graphite, sand blasting may be further performed before the shot blasting is performed. By performing sand blasting, the graphite removal rate can be further improved.

The waste SiC after the graphite removal step does not contain graphite.

Crushing waste SiC

The method of manufacturing SiC powder according to an embodiment includes the step of pulverizing the waste SiC from which the graphite has been removed.

According to an embodiment, the grinding step may include a first grinding step and a second grinding step. In addition, the crushing step may be performed using a jaw crusher, a ball mill, a steel ball, or the like.

Specifically, the first grinding step may be performed using a jaw crusher. Specifically, the SiC may be pulverized to a size of 10 μm to 100 mm. For example, the SiC is 10 μm to 1,000 μm, 100 μm to 800 μm, 10 μm to 5,000 μm, 50 μm to 100 mm, 100 μm to 100 mm, 1,000 μm to 100 mm, 0.1 mm to 100 mm, It can be pulverized into 0.1 mm to 80 mm, 10 mm to 80 mm or 30 mm to 50 mm. In addition, the jaw crusher may be performed at a rotation speed of 100 RPM to 800 RPM, 200 RPM to 600 RPM, or 300 RPM to 500 RPM.

In addition, the second grinding step may be performed using a ball mill. Specifically, the SiC may be pulverized into 10 nm to 100 mm. For example, the SiC is 100 nm to 1,000 nm, 300 nm to 1,000 nm, 500 nm to 5,000 nm, 0.1 mm to 100 mm, 0.1 mm to 80 mm, 10 mm to 80 mm, or 30 mm to 50 mm. Can be crushed.

In addition, the second pulverization step may be performed using a steel ball. Specifically, using a steel ball of 1 mm to 40 mm, 1 mm to 35 mm, 3 mm to 30 mm or 5 mm to 30 mm, 20 minutes or more, 20 minutes to 60 minutes, 20 minutes to 50 minutes, 20 minutes To 40 minutes or 20 to 30 minutes.

Step of screening waste SiC

According to one embodiment, after the pulverizing step, it may further include a step of sorting the pulverized waste SiC (hereinafter, a sorting step).

Specifically, in the sorting step, the pulverized waste SiC may be sorted according to a desired size using a sorter. For example, they may be classified according to sizes of less than 100 μm, 100 μm or more and 150 μm, 150 μm or more and 350 μm, and 350 μm or more and less than 5,000 μm, but are not limited thereto.

According to one embodiment, the sorting step may be performed using a twist screen which is a vibration sorting device.

The twist screen may be made of a silicone material having a diameter of 10 mm to 80 mm, 15 mm to 70 mm, or 20 mm to 60 mm using a tapping ball, and performed for 10 to 100 minutes under conditions of 1,000 RPM to 3,000 RPM. Can be. In addition, the pulverized waste SiC may be added to the twist screen at a constant rate, and the input rate may be 1 mm/s to 1,000 mm/s, but is not limited thereto.

Step of removing iron (Fe) component

A method of manufacturing SiC powder according to an embodiment includes removing the iron (Fe) component from the pulverized waste SiC. Specifically, the step of removing the iron component is a step of removing iron components that can be adsorbed on the waste SiC in the pulverization step, and more specifically, removing iron ions that can be adsorbed on the waste SiC in the second grinding step. Step.

This step may be performed using a rotary metal detector. Specifically, the iron component can be effectively removed by controlling the input rate using magnetic force.

At this time, when the rotation speed of the rotating metal detector is 100 RPM or more and 800 RPM or less, the power of the electromagnet is 0.5 kW or more and 3 kW or less, and when the rotation speed of the rotating metal detector is more than 800 RPM and 1,700 RPM or less, the power of the electromagnet may be more than 3 kW and 5.3 kW or less. have.

The waste SiC from which the iron component has been removed by the above step may contain iron in an amount of 1 ppm or less, more specifically 0.5 ppm or less, 0.3 ppm or less, or 0.1 ppm or less.

Cleaning steps

A method of manufacturing SiC powder according to an embodiment includes the step of cleaning waste SiC from which the iron component has been removed.

According to one embodiment, the washing step comprises (a) a first washing step, (b) a leaching step, (c) a first immersion step, (d) a second washing step, and (e) a second immersion step. I can.

According to one embodiment, in the cleaning step, a cleaning liquid containing hydrogen fluoride may be used.

The first washing step (a) may be performed for 1 minute to 300 minutes using ultrapure water or pure water. For example, the step (a) is 1 minute to 250 minutes, 1 minute to 200 minutes, 3 minutes to 150 minutes, 10 minutes to 100 minutes, 15 minutes to 80 minutes, 20 minutes to 60 minutes, 20 minutes to 40 minutes Can be run for minutes.

The leaching step (b) is a step of leaching waste SiC using a cleaning solution containing hydrogen fluoride, and an agitation method may be used. For example, the step (b) is 1 minute to 300 minutes, 1 minute to 250 minutes, 1 minute to 200 minutes, 3 minutes to 150 minutes, 10 minutes to 100 minutes, 15 minutes to 80 minutes, 20 minutes to 60 minutes Minutes, can be carried out for 20 to 40 minutes.

The first deposition step (c) is a step of depositing waste SiC using a cleaning solution containing hydrogen fluoride. For example, the step (c) is 1 minute to 300 minutes, 1 minute to 250 minutes, 1 minute to 200 minutes, 3 minutes to 150 minutes, 10 minutes to 100 minutes, 15 minutes to 80 minutes, 20 minutes to 60 minutes Minutes, can be carried out for 20 to 40 minutes.

The second washing step (d) uses distilled water for 1 minute to 300 minutes, 1 minute to 250 minutes, 1 minute to 200 minutes, 3 minutes to 150 minutes, 10 minutes to 100 minutes, 15 minutes to 80 minutes, 20 It can be carried out for minutes to 60 minutes, 20 minutes to 40 minutes.

The second deposition step (e) is a step of depositing waste SiC using a cleaning solution containing hydrogen fluoride. For example, the step (e) is 1 minute to 300 minutes, 1 minute to 250 minutes, 1 minute to 200 minutes, 3 minutes to 150 minutes, 10 minutes to 100 minutes, 15 minutes to 80 minutes, 20 minutes to 60 minutes Minutes, can be carried out for 20 to 40 minutes.

The steps (a) to (e) may be performed for 2 hours to 5 hours or 3 hours. In the washing step, steps (a) to (e) may be performed 3 or more times or 3 to 5 times.

By performing the cleaning step, there is an advantageous effect in maximizing the purity of the SiC powder.

Measuring the content of other ingredients

The method of manufacturing SiC powder according to an embodiment may further include measuring the content of the iron component after the step of cleaning the waste SiC.

According to one embodiment, the purity of the SiC powder after the cleaning step is 95% to 99.9999%, 95% to 99.99999%, 96% to 99.9999%, 96% to 99.99999%, 97% to 99.9999%, 97% to 99.99999% %, 98% to 99.9999%, 98% to 99.99999%, 99% to 99.9999%, or 99% to 99.99999% purity.

According to one embodiment, the SiC powder after the cleaning step is selected from the group consisting of Li, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn and Mo One or more types of impurities may be included in an amount of 1 ppm or less, 0.8 ppm or less, 0.7 ppm or less, 0.1 to 0.7 ppm, or 0.1 to 0.6 ppm.

According to one embodiment, the average particle diameter of the SiC powder after the cleaning step may be 10 μm to 100 mm. For example, it may be 10 µm to 5,000 µm, 50 µm to 1,000 µm, 100 µm to 2,000 µm, or 1,000 µm to 10,000 µm.

According to one embodiment, the standard deviation of the average particle diameter of the SiC powder after the cleaning step may be 1 µm to 30 µm. For example, it may be 1 µm to 25 µm, 3 µm to 20 µm, or 5 µm to 20 µm.

Claims (19)

Cutting the waste SiC;
Removing graphite from the cut waste SiC;
Pulverizing the waste SiC from which the graphite has been removed;
Removing the iron (Fe) component from the pulverized waste SiC; And
Cleaning the waste SiC from which the iron component has been removed; containing, a method for producing a high-purity SiC powder. The method of claim 1,
The step of removing the graphite is performed by shot blasting, a method for producing a high purity SiC powder. The method of claim 1,
In the step of removing the graphite, the method of producing a high-purity SiC powder further comprising the step of oxidizing the waste SiC. The method of claim 3,
The oxidation step is carried out at 500 to 1,200 ℃, the method of producing a high purity SiC powder. The method of claim 3,
The method of manufacturing a high purity SiC powder, wherein the oxidation step includes a first oxidation step and a second oxidation step. The method of claim 5,
The first oxidation step is performed at 500 to 1,200°C for 5 to 30 hours,
The second oxidation step is carried out at 500 to 1,200 ℃ for 5 to 20 hours, a method of producing a high purity SiC powder. The method of claim 3,
The step of removing the graphite is performed by shot blasting,
A method for producing a high purity SiC powder comprising the step of oxidizing waste SiC before or after the shot blasting. The method of claim 7,
The step of removing the graphite includes a first oxidation step, a shot blasting step, and a second oxidation step. The method of claim 1,
The step of removing the graphite further comprises a quenching (quenching) step, the method of producing a high purity SiC powder. The method of claim 9,
The quenching step is carried out at 0 to 60 ℃, a method for producing a high purity SiC powder. The method of claim 9,
The method of manufacturing a high purity SiC powder, wherein the quenching step includes a first quenching step and a second quenching step. The method of claim 11,
The first quenching step is performed at 15 to 50° C. for 1 minute or more to less than 10 minutes,
The second quenching step is carried out at 0 to 15 ℃ for 1 to 10 minutes, the method of producing a high purity SiC powder. The method of claim 9,
The quenching step is performed in one or more solvents selected from the group consisting of tap water, distilled water, deionized water, methanol, and ethanol. The method of claim 9,
In the quenching step, a solvent is used by mixing with at least one refrigerant selected from the group consisting of dry ice, ice pack, and ice. The method of claim 1,
The step of removing the graphite comprises a first oxidation step, a first quenching step, a shot blasting step, a second oxidation step, and a second quenching step. The method of claim 1,
The step of cleaning the waste SiC is performed using a cleaning liquid containing hydrogen fluoride, a method for producing a high purity SiC powder. The method of claim 1,
After the step of washing the waste SiC, the method of manufacturing a high-purity SiC powder further comprising the step of measuring the content of the iron component. The method of claim 1,
The purity of the SiC powder is 95% to 99.99999%, a method for producing a high purity SiC powder. The method of claim 1,
The SiC powder contains at least one impurity selected from the group consisting of Li, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, and Mo to 1 ppm or less. Containing, a method for producing a high-purity SiC powder.