Preparation apparatus for SiC powder and preparation method for SiC powder

Abstract

The present invention provides a preparation device for high-purity SiC powder and a preparation method for high-purity SiC powder. First, nanoscale SiC powder is loaded as a seed crystal at the inner top of a vertical growth furnace. Secondly, the temperature of the upper cavity of the vertical growth furnace is heated to the growth temperature. Thirdly, a first carrier gas and / or a material gas are introduced into the upper cavity through a first gas preparation chamber. Thirdly, the seed crystal is blown into the reaction chamber by a second carrier gas, and the seed crystal is suspended in the reaction chamber under the action of an upward-moving gas flow. The material gas undergoes a chemical reaction at high temperature and heterogeneously nucleates into high-purity millimeter-scale SiC powder with the seed crystal as the nucleation center. Finally, the above-mentioned millimeter-scale SiC powder is collected by a powder collector. The silicon carbide powder prepared by the above method has high purity and uniform particle size and can be used to prepare high-quality semi-insulating SiC single crystals.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon carbide materials, and particularly relates to a preparation device and a preparation method for SiC powder. Background Art

[0002] SiC is a third-generation semiconductor material with a wide bandgap, high thermal conductivity, high breakdown field strength, high saturation drift velocity, and radiation resistance, and is a key material for manufacturing high-temperature, high-frequency, high-power, radiation-resistant, and ultra-high-voltage power electronic devices. SiC powder, as a raw material required in fields such as single crystal growth of silicon carbide, piezoelectric crystal wafers, and silicon carbide ceramics, its quality directly affects the quality and performance of the finished products. Currently, SiC powder is mainly prepared by the carbothermal reduction method or the sol-gel method. However, these preparation methods are prone to introducing other impurities during the preparation process of silicon carbide powder, resulting in low purity of SiC powder and being unable to meet the growth requirements of SiC single crystals.

[0003] Chemical vapor deposition (CVD) is used to prepare SiC powder through high-temperature gas-phase reactions. Its powder has extremely high purity, especially the impurity content of N element is very low, and it can be used for growing semi-insulating SiC single crystals. However, the SiC powder prepared by the traditional CVD method has the disadvantages of low yield and small particle size (nanoscale), and it is difficult to meet the requirements for industrial preparation of SiC semiconductor devices. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation device and a preparation method for SiC powder, which are used to solve the technical problem that it is difficult for existing CVD devices to prepare SiC powder with high purity and large particle size.

[0005] To solve the above technical problem, the present invention first provides a preparation device for SiC powder, including:

[0006] A vertical growth furnace;

[0007] A seed crystal placement chamber, installed at the inner top of the vertical growth furnace, for loading nanoscale SiC powder as a seed crystal;

[0008] A first gas preparation chamber, installed at the outer bottom of the vertical growth furnace, for mixing and introducing a first carrier gas and / or a material gas into the interior of the vertical growth furnace;

[0009] A second gas preparation chamber, installed outside the vertical growth furnace and communicating with the interior of the seed crystal placement chamber, for introducing a second carrier gas into the seed crystal placement chamber to blow the seed crystal onto the powder collector; and

[0010] Multiple heating components are fixed to the outer sidewall of the vertical growth furnace. The heating components are used to heat the seed crystal located inside the vertical growth furnace to a preset growth temperature, so that the seed crystal reacts with the material gas to heterogeneously nucleate into millimeter-sized SiC powder; and

[0011] A powder collector is installed at the inner bottom end of the vertical growth furnace and is arranged away from the heating components. The powder collector is used to collect millimeter-sized SiC powder.

[0012] Preferably, the seed crystal placement chamber is suspended at the inner top end of the vertical growth furnace through a pipeline connected to the second gas preparation chamber. The seed crystal placement chamber includes a bottom plate, and the bottom plate has a plurality of material leakage holes, and the aperture of the material leakage holes is 1 μm to 5 μm.

[0013] Preferably, one side of the seed crystal placement chamber is fixed to the inner wall of the vertical growth furnace, and the other side of the seed crystal placement chamber is an opening, and the opening is correspondingly arranged with the second air outlet provided in the second gas preparation chamber.

[0014] Preferably, the preparation device further includes a gas distribution plate, and the gas distribution plate is embedded at the bottom end of the vertical growth furnace and is located below the powder collector;

[0015] Wherein, the gas distribution plate is correspondingly connected to the first air outlet of the first gas preparation chamber, and the gas distribution plate has a plurality of first air outlet holes, and the aperture of the first air outlet holes is 5 mm to 10 mm.

[0016] Preferably, the powder collector has a plurality of second air outlet holes, and the aperture of the second air outlet holes is 0.1 mm to 1 mm.

[0017] Preferably, a gas cloth and an air outlet channel are sequentially arranged above the seed crystal placement chamber. The gas cloth is used to block the seed crystal and enable the mixed gas in the vertical growth furnace to flow out through the air outlet channel.

[0018] Preferably, the heating component includes any one of an induction coil for high-frequency heating, a heater for resistance heating, or a lamp for heating.

[0019] Correspondingly, the present invention also provides a method for preparing SiC powder, including:

[0020] S10, providing the SiC powder preparation device as described in any one of the above;

[0021] S20, loading a seed crystal in the seed crystal placement chamber;

[0022] S30, heating the temperature of the upper cavity to the growth temperature through a plurality of heating components installed on the outer sidewall of the upper cavity of the vertical growth furnace;

[0023] S40, introducing the first carrier gas and / or the material gas into the upper cavity through the first gas preparation chamber;

[0024] S50. Introduce the second carrier gas into the seed crystal placement chamber, so that the seed crystal undergoes free-fall motion into the upper cavity, and after reacting with the material gas, heterogeneous nucleation forms millimeter-sized SiC powder.

[0025] S60. Collect the millimeter-sized SiC powder through a powder collector.

[0026] Preferably, in step S30, the growth temperature range is 1200 - 1800 °C; in step S40, the pressure range of the mixed gas introduced from the first gas preparation chamber into the vertical growth furnace is 5 - 50 KPa.

[0027] Preferably, in steps S40 and S50, both the first carrier gas and the second carrier gas include at least one of H 2 , Ar, and N 2 ; the material gas includes any one of (CH 3 ) 2 SiCl 2 , Si(CH 3 ) 4 , and SiCl 3 CH 3 .

[0028] The beneficial effects of the present invention are as follows: Different from the prior art, the present invention provides a preparation device for SiC powder and a preparation method for SiC powder. First, a seed crystal is loaded at the inner top of a vertical growth furnace. Secondly, the temperature of the upper cavity of the vertical growth furnace is heated to a preset growth temperature. Thirdly, the first carrier gas and / or the material gas are introduced into the upper cavity through the first gas preparation chamber. Thirdly, the seed crystal undergoes free-fall motion into the upper cavity through the second carrier gas, and after the seed crystal reacts with the material gas, heterogeneous nucleation forms high-purity millimeter-sized SiC powder. Finally, the above-mentioned millimeter-sized SiC powder is collected through a powder collector, thereby meeting the requirements for industrial preparation of high-purity SiC single crystals. Description of the Drawings

[0029] Figure 1 It is a schematic diagram of the main structure of the SiC powder preparation device provided in Embodiment 1 of the present invention;

[0030] Figure 2 It is a schematic diagram of the structure of the powder collector in the SiC powder preparation device provided in Embodiment 1 of the present invention;

[0031] Figure 3 It is a schematic diagram of the structure of the gas distribution plate in the SiC powder preparation device provided in Embodiment 1 of the present invention;

[0032] Figure 4Schematic diagram of the structure in which the vertical growth furnace in the SiC powder preparation device provided in Embodiment 1 of the present invention is respectively connected to the first gas preparation chamber and the tail gas treatment system;

[0033] Figure 5 Schematic diagram of the main structure of the SiC powder preparation device provided in Embodiment 2 of the present invention;

[0034] Figure 6 Flow chart of the SiC powder preparation method provided in the embodiments of the present invention. Detailed implementation manners

[0035] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] Now, the technical solutions of the present invention will be further described in conjunction with specific embodiments.

[0037] Embodiment 1:

[0038] Please refer to Figures 1 to 4 , Figure 1 Schematic diagram of the main structure of the SiC powder preparation device provided in Embodiment 1 of the present invention; Figure 2 Schematic diagram of the structure of the powder collector 15 in the SiC powder preparation device provided in Embodiment 1 of the present invention; Figure 3 Schematic diagram of the structure of the gas distribution plate 16 in the SiC powder preparation device provided in Embodiment 1 of the present invention; Figure 4 Schematic diagram of the structure in which the vertical growth furnace 10 in the SiC powder preparation device provided in Embodiment 1 of the present invention is respectively connected to the first gas preparation chamber 12 and the tail gas treatment system 18.

[0039] In the embodiment of the present invention, the SiC powder preparation device provided in Embodiment 1 of the present invention includes a vertical growth furnace 10. The diameter of the vertical growth furnace 10 is 500 - 800 mm, and the height is 2000 - 5000 mm. The inner wall of the reaction chamber of the vertical growth furnace 10 is made of graphite material, and the outer wall is made of quartz material.

[0040] In the embodiment of the present invention, the seed crystal placement chamber 11 is installed at the inner top of the vertical growth furnace 10 and is used to load nanoscale SiC powder as the seed crystal 21. The particle size of the seed crystal 21 is 20 - 100 nm, and the seed crystal 21 is prepared by the traditional CVD method.

[0041] In an embodiment of the present invention, the first gas preparation chamber 12 is installed at the outer bottom end of the vertical growth furnace 10, and is used for mixing the first carrier gas and / or the material gas, adjusting the pressure, and introducing the gas into the interior of the vertical growth furnace 10 through the gas inlet channel 102.

[0042] Specifically, the first carrier gas includes at least one of H 2 , Ar, and N 2 ; the material gas includes any one of (CH 3 ) 2 SiCl 2 , Si(CH 3 ) 4 , and SiCl 3 CH 3 ; the material gas may also include other C source gases (such as CH 4 , C 3 H 8 ) and Si source gases (such as SiCl 4 ).

[0043] In an embodiment of the present invention, the second gas preparation chamber 13 is installed outside the vertical growth furnace 10 and communicates with the interior of the seed crystal placement chamber 11, and is used for introducing the second carrier gas into the seed crystal placement chamber 11 to blow the seed crystal 21 onto the powder collector 15; specifically, the second carrier gas includes at least one of H 2 , Ar, and N 2 .

[0044] In an embodiment of the present invention, a plurality of heating components 14 are fixed to the outer side wall of the vertical growth furnace 10 (corresponding to the upper cavity 101 of the reaction chamber, that is, the heating area of the reaction chamber), and the heating components 14 are used to heat the seed crystal 21 located in the vertical growth furnace 10 to a preset growth temperature, so that the seed crystal 21 reacts with the material gas to heterogeneously nucleate into millimeter-sized SiC powder 22.

[0045] In an embodiment of the present invention, the powder collector 15 is installed at the inner bottom end of the vertical growth furnace 10 and is arranged away from the heating components 14 (corresponding to the lower cavity of the reaction chamber, that is, the non-heating area of the reaction chamber), and the powder collector 15 is used to collect millimeter-sized SiC powder 22, and the particle size of the millimeter-sized SiC powder 22 is 0.1 - 1 mm.

[0046] Preferably, the seed crystal placement chamber 11 is suspended at the inner top end of the vertical growth furnace 10 through a pipeline 131 connected to the second gas preparation chamber 13. The seed crystal placement chamber 11 includes a bottom plate 111, and the bottom plate 111 has a plurality of material leakage holes with a pore diameter of 1 μm - 5 μm; wherein, the seed crystal 21 in the seed crystal placement chamber 11 enters the upper cavity 101 of the reaction chamber through the material leakage holes.

[0047] Please refer to Figure 1 and Figure 3 , the preparation device further includes a gas distribution plate 16, which is embedded in the bottom end of the vertical growth furnace 10 and is located below the powder collector 15; wherein, the gas distribution plate 16 is correspondingly connected to the first air outlet of the first gas preparation chamber 12, the gas distribution plate 16 has a plurality of first air holes 161, and the aperture of the first air holes 161 is 5 mm to 10 mm; the first air holes 161 are used to adjust the flow rate of the mixed gas input into the reaction chamber from the first gas preparation chamber 12.

[0048] Please refer to Figure 1 and Figure 2 , the powder collector 15 has a plurality of second air holes 151, and the aperture of the second air holes 151 is 0.1 mm to 1 mm; the mixed gas input into the reaction chamber from the first gas preparation chamber 12 enters the upper cavity 101 of the reaction chamber through the second air holes 151 in the powder collector 15.

[0049] Please refer to Figure 1 , above the seed crystal placement chamber 11, a gas cloth 17 and an air outlet channel 103 are sequentially arranged. The gas cloth 17 is used to block the seed crystal 21 and enable the mixed gas in the vertical growth furnace 10 to flow out through the air outlet channel 103.

[0050] Please refer to Figure 4 , Figure 4 is a schematic structural diagram of the heating assembly 14 being respectively connected to the first gas preparation chamber 12 and the tail gas treatment system 18 in the SiC powder preparation device provided in Embodiment 1 of the present invention; wherein, the SiC powder preparation device further includes a tail gas treatment system 18, and the tail gas treatment system 18 includes a cold trap, a chemical impurity removal component, a particle filtration component, an air pump, and a washing component. The cold trap is used to cool the gas flowing out through the air outlet channel 103, and the washing component includes a NaOH solution for absorbing the chloride gas (such as HCl) in the mixed gas.

[0051] In the embodiment of the present invention, the first gas preparation chamber 12 includes a first gas cylinder 121, a carbon raw material, a silicon raw material, and a plurality of MFCs (micro functional circuits); the first gas cylinder loads at least one of H 2 , Ar, and N 2 , the carbon raw material and the silicon raw material are placed in a constant temperature container 122, and the gas in the first gas cylinder 121 is used as a carrier gas and is transported to the first gas preparation chamber 12 by the bubbling method.

[0052] In the embodiment of the present invention, the heating assembly 14 includes any one of an induction coil for high-frequency heating, a heater for resistance heating, or a lamp for heating, and preferably an induction coil for high-frequency heating.

[0053] In an embodiment of the present invention, the preparation apparatus for SiC powder further includes a control system 20, which is used to adjust the gas flow rate and velocity in the first gas preparation chamber 12, and monitor and control the pressure and growth temperature of the mixed gas in the vertical growth furnace 10.

[0054] Embodiment 2:

[0055] Please refer to Figure 5 , Figure 5 , which is a schematic diagram of the main structure of the SiC powder preparation apparatus provided in Embodiment 2 of the present invention; the main structure of the SiC powder preparation apparatus provided in Embodiment 2 of the present invention is substantially the same as that of the SiC powder preparation apparatus provided in Embodiment 1 of the present invention, except that: the installation position of the seed crystal placement chamber 11 is different.

[0056] In an embodiment of the present invention, one side of the seed crystal placement chamber 11 is fixed to the inner wall of the vertical growth furnace 10, and the other side of the seed crystal placement chamber 11 is an opening, and the opening is correspondingly arranged with the second gas outlet provided in the second gas preparation chamber 13.

[0057] Please refer to Figures 1 to 6 , Figure 6 , which is a flowchart of the SiC powder preparation method provided in an embodiment of the present invention; wherein, the above preparation method includes:

[0058] S10, provide a preparation apparatus for SiC powder.

[0059] S20, load nano-scale SiC powder as the seed crystal 21 in the seed crystal placement chamber 11.

[0060] In one embodiment, the particle size of the seed crystal 21 is 20 - 100 nm, preferably 50 nm.

[0061] S30, heat the temperature of the upper cavity 101 to a preset growth temperature through a plurality of heating components 14 installed on the outer wall of the upper cavity 101 of the vertical growth furnace 10;

[0062] In one embodiment, the above preset growth temperature is 1300 °C.

[0063] S40, introduce the first carrier gas and / or material gas into the upper cavity 101 through the first gas preparation chamber 12.

[0064] In one embodiment, the first carrier gas is selected as H 2 , and the material gas is SiCl 3 CH 3 , and the pressure range of the mixed gas introduced from the first gas preparation chamber 12 into the vertical growth furnace 10 is 5 - 50 KPa.

[0065] S50. Introduce the second carrier gas into the seed crystal placement chamber 11 so that the seed crystal 21 undergoes free-fall motion into the upper cavity 101 and reacts with the material gas to heterogeneously nucleate into millimeter-sized SiC powder 22.

[0066] S60. Collect the millimeter-sized SiC powder 22 through the powder collector 15.

[0067] Specifically, the reaction principle of the seed crystal 21 reacting with the material gas to heterogeneously nucleate into millimeter-sized SiC powder 22 is as follows:

[0068] The seed crystal 21 falls into the upper cavity 101 of the reaction chamber through the micron-sized leakage hole under the action of gravity. At the same time, SiCl 3 CH 3 successively enters the upper cavity 101 of the reaction chamber through the first air outlet 161 and the second air outlet 151; SiCl 3 CH 3 In a growth environment of 1300 °C, on the one hand, nanometer-sized SiC powder with a particle size equivalent to that of the seed crystal 21 is obtained through homogeneous nucleation, and on the other hand, millimeter-sized SiC powder 22 is nucleated and grown with the seed crystal 21 in the reaction chamber as a carrier through heterogeneous nucleation. The particle size of the millimeter-sized SiC powder 22 is 0.1 - 1 mm.

[0069] Specifically, the reaction equation in the above process is: SiCl 3 CH 3 → SiC + 3HCl.

[0070] The force analysis of SiC powder with different particle sizes is as follows:

[0071] Assume that the SiC powder is a spherical particle (the actual SiC powder is not a spherical particle). The upward buoyancy force F on the SiC powder during the falling process is: F = P * S = P * (πr 2 ), and the gravitational force G on the SiC powder during the falling process is: G = ρ * v * g = ρ * (4 / 3πr 3 ) * g;

[0072] Among them, S is the cross-sectional area of the SiC powder, P is the pressure of the upward air flow on the SiC powder, ρ is the density of the SiC powder, v is the volume of the SiC powder, g is the gravitational acceleration constant, and r is the radius of the SiC powder.

[0073] Specifically, when G = F, then P = 4 / 3ρrg, and r 0 is the critical radius of the SiC powder; therefore, the pressure P of the upward air flow on the SiC powder is linearly and positively correlated with the critical radius r 0 of the SiC powder. 0 shows a linear positive correlation.

[0074] Furthermore, SiC powder with different particle sizes in the reaction chamber is subject to its own gravity and the buoyancy of the upward airflow (the first carrier gas and / or the material gas). Different buoyancies correspond to different critical radii of SiC powder. When the radius of the SiC powder exceeds the critical radius, the SiC powder descends and detaches from the upper cavity 101 and falls onto the powder collector 15 at the bottom of the reaction chamber, thereby obtaining millimeter-sized SiC powder 22. Therefore, by adjusting the flow rate and velocity of the upward airflow, the pressure exerted on the SiC powder can be controlled, and thus the particle size of the prepared millimeter-sized SiC powder 22 can be adjusted.

[0075] Specifically, set the flow rate of H 2 to be 5 - 10 times the flow rate of SiCl 3 CH 3 By adjusting process parameters such as the pressure and flow rate of the mixed gas introduced into the vertical growth furnace 10 from the first gas preparation chamber 12, and combining with fluid mechanics simulation software, the buoyancy F exerted on the silicon carbide powder at the bottom of the reaction chamber of the vertical growth furnace can be obtained. The relationship between the buoyancy F and the particle size corresponding to the millimeter-sized SiC powder 22 is as follows:

[0076] When the buoyancy (drag force) exerted on the silicon carbide powder at the bottom of the reaction chamber of the vertical growth furnace is 40 Pa, the particle size of the prepared millimeter-sized SiC powder 22 is about 1 mm; when the buoyancy is 4 Pa, the particle size of the prepared millimeter-sized SiC powder 22 is about 0.1 mm; when the buoyancy is 10 Pa, the particle size of the prepared millimeter-sized SiC powder 22 is about 0.25 mm.

[0077] As described above, by adjusting process parameters such as gas flow rate and flow, the buoyancy exerted on the silicon carbide powder in the reaction chamber can be adjusted, and thus high-purity silicon carbide powder with adjustable particle size can be prepared.

[0078] In summary, the present invention provides a preparation device and a preparation method for SiC powder. First, a seed crystal 21 is loaded at the inner top of the vertical growth furnace 10. Secondly, the temperature of the upper cavity 101 of the vertical growth furnace 10 is heated to a preset growth temperature. Thirdly, the first carrier gas and / or the material gas are introduced into the upper cavity 101 through the first gas preparation chamber 12. Thirdly, the seed crystal 21 is made to fall freely into the upper cavity 101 through the second carrier gas, so that the seed crystal 21 reacts with the material gas to heterogeneously nucleate into high-purity millimeter-sized SiC powder 22. Finally, the above-mentioned millimeter-sized SiC powder 22 is collected by the powder collector 15, thereby meeting the requirements for industrial preparation of high-purity SiC single crystals.

[0079] It should be noted that the above embodiments all belong to the same inventive concept. Each embodiment description has its own focus. For the parts not described in detail in individual embodiments, reference can be made to the descriptions in other embodiments.

[0080] The above embodiments only express the implementation manners of the present invention. The descriptions are relatively specific and detailed, but should not be construed as limiting the scope of the invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the inventive concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A preparation device for SiC powder, characterized in that, it includes: A vertical growth furnace; A seed crystal placement chamber, installed at the inner top of the vertical growth furnace, for loading nanoscale SiC powder as a seed crystal; A first gas preparation chamber, installed at the outer bottom of the vertical growth furnace, for mixing and introducing the first carrier gas and / or material gas into the interior of the vertical growth furnace; A second gas preparation chamber, installed outside the vertical growth furnace and communicating with the interior of the seed crystal placement chamber, for introducing the second carrier gas into the seed crystal placement chamber to blow the seed crystal outside the seed crystal placement chamber; And A plurality of heating components, fixed to the outer side wall of the vertical growth furnace, the heating components being used to heat the seed crystal to a preset growth temperature so that the seed crystal reacts with the material gas to heterogeneously nucleate into millimeter-scale SiC powder; And A powder collector, installed at the inner bottom of the vertical growth furnace and set away from the heating components, the powder collector being used to collect the millimeter-scale SiC powder, the powder collector having a plurality of second air outlet holes, and the aperture of the second air outlet holes being 0.1 mm to 1 mm; Wherein, the seed crystal placement chamber is suspended at the inner top of the vertical growth furnace through a pipeline connected to the second gas preparation chamber, the seed crystal placement chamber includes a bottom plate, the bottom plate having a plurality of material leakage holes, and the aperture of the material leakage holes being 1 μm to 5 μm; the preparation device further includes a gas distribution plate, the gas distribution plate being embedded at the bottom of the vertical growth furnace and located below the powder collector; the gas distribution plate is correspondingly connected to the first air outlet of the first gas preparation chamber, and the gas distribution plate has a plurality of first air outlet holes, and the aperture of the first air outlet holes being 5 mm to 10 mm.

2. The preparation device for SiC powder according to claim 1, characterized in that, One side of the seed crystal placement chamber is fixed to the inner wall of the vertical growth furnace, and the other side of the seed crystal placement chamber is an opening, and the opening is correspondingly arranged with the second air outlet arranged in the second gas preparation chamber.

3. The preparation device for SiC powder according to claim 1, characterized in that, A gas cloth and an air outlet channel are sequentially arranged above the seed crystal placement chamber, and the gas cloth is used to block the seed crystal and enable the mixed gas in the vertical growth furnace to flow out through the air outlet channel.

4. The preparation device for SiC powder according to claim 1, characterized in that, The heating component includes any one of an induction coil for high-frequency heating, a heater for resistance heating, or a lamp for heating.

5. A preparation method for SiC powder, characterized in that, it includes: S10, providing the preparation device for SiC powder according to any one of claims 1 to 4; S20, loading the seed crystal in the seed crystal placement chamber; S30, heating the temperature of the upper cavity to the growth temperature through a plurality of heating components installed on the outer side wall of the upper cavity of the vertical growth furnace; S40, introducing the first carrier gas and / or the material gas into the upper cavity through the first gas preparation chamber; S50, Introduce the second carrier gas into the seed crystal placement chamber, so that the seed crystal undergoes free-fall motion into the upper cavity, and after reacting with the material gas, heterogeneous nucleation occurs to form millimeter-sized SiC powder. S60, Collect the millimeter-sized SiC powder through the powder collector.

6. The method for preparing SiC powder according to claim 5, characterized in that, in the step S30, the growth temperature range is 1200~1800°C; in the step S40, the pressure range of the mixed gas introduced from the first gas preparation chamber into the vertical growth furnace is 5~50 KPa.

7. The method for preparing SiC powder according to claim 5, characterized in that, In the step S40 and the step S50, the first carrier gas and the second carrier gas both include H 2 , Ar and N 2 At least one of; the material gas includes (CH 3 ) 2 SiCl 2 、Si(CH 3 ) 4 and SiCl 3 CH 3 Any one of .

Images