Synthesis apparatus of high-purity silicon carbide powder

Abstract

The application discloses a kind of synthesis devices of high-purity silicon carbide powder, synthesis device includes: crucible;Bin, bin is located in crucible and is fixed in the top of crucible, bin and crucible between limit out loading area, loading area is equipped with the partition vertical board;Silicon material switch door and carbon material switch door, silicon material switch door is used to open or close silicon material export, carbon material switch door is used to open or close carbon material export;Uniform bin;Driving motor and rotating shaft, the top of rotating shaft is equipped with first-stage scraper;Second-stage multi-hole plate, driving motor is driven first-stage scraper and second-stage multi-hole plate synchronous rotation by rotating shaft;Second-stage scraper, second-stage scraper is multiple and located above second-stage multi-hole plate;Side heater group and bottom heater, side heater group includes multiple resistance heating rings, and each resistance heating ring is independently controlled.According to the synthesis device of the application, the problem of elemental inclusion in silicon carbide powder can be reduced, which is beneficial to improve the purity of silicon carbide powder.

Description

Technical Field

[0001] This invention relates to the field of silicon carbide raw materials, and in particular to an apparatus for synthesizing high-purity silicon carbide powder. Background Technology

[0002] Silicon carbide, as a representative of third-generation semiconductors, plays an important role in fields such as new energy. One of the key raw materials for silicon carbide crystals is high-purity silicon carbide powder. The purity of silicon carbide powder directly affects the quality of silicon carbide crystals, significantly influencing their conductivity, dislocation density, and impurity content. Therefore, obtaining high-quality silicon carbide crystals requires high-purity silicon carbide powder as a raw material.

[0003] In the related technologies, silicon carbide powder synthesis devices generally synthesize silicon carbide powder by uniformly mixing carbon and silicon materials and then heating them. However, the synthesized product contains inclusions, resulting in low purity of silicon carbide powder. Furthermore, it is easy to synthesize silicon carbide powder particles with multiple crystal forms, resulting in a low proportion of homogeneous crystal forms. Therefore, how to improve the synthesis purity of silicon carbide powder and increase the proportion of homogeneous crystal forms is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] This invention is based on this. In actual research, the inventors discovered that in related technologies, after carbon and silicon materials are uniformly mixed and heated, the synthesized product contains hard solids that cannot be crushed. Even after these hard solids are returned to the furnace, they still cannot become loose. Only a thin outer layer reacts to form SiC. This is because silicon materials are in close contact with each other. Silicon materials have a low melting point. When silicon materials begin to sublimate, they react with the surrounding carbon powder to form a hard silicon carbide shell on the surface of the silicon materials. This shell prevents further sublimation of silicon, which leads to a decrease in product purity.

[0005] Therefore, the present invention provides a device for synthesizing high-purity silicon carbide powder, which can reduce the problem of elemental inclusions inside silicon carbide powder and improve the purity of silicon carbide powder.

[0006] An apparatus for synthesizing high-purity silicon carbide powder according to an embodiment of the present invention includes: a crucible; a hopper, the hopper being disposed inside the crucible and fixed to the top of the crucible, a loading area defining a loading zone between the hopper and the crucible, the loading zone being provided with a dividing vertical plate, the dividing vertical plate dividing the loading zone into a silicon material zone and a carbon material zone spaced apart in the left-right direction, the bottom of the silicon material zone having a silicon material outlet, the bottom of the carbon material zone having a carbon material outlet; a silicon material switch door and a carbon material switch door, the silicon material switch door being disposed at the silicon material outlet, the silicon material switch door being used to open or close the... A silicon material outlet is provided, and a carbon material switch door is located at the carbon material outlet. The carbon material switch door is used to open or close the carbon material outlet. A material equalization silo is connected below the material silo. The bottom of the material equalization silo is provided with a perforated plate. When the silicon material switch door opens the silicon material outlet and the carbon material switch door closes the carbon material outlet, only silicon material falls into the material equalization silo through the silicon material outlet. When the silicon material switch door closes the carbon material outlet and the carbon material switch door opens the carbon material outlet, only carbon material falls into the material equalization silo through the carbon material outlet. A drive motor and... A rotating shaft, with the drive motor positioned below the crucible, extends into the crucible from its bottom. The output of the drive motor is connected to the rotating shaft. A primary scraper is located at the top of the rotating shaft within the material equalization hopper. A secondary perforated plate is positioned below and spaced apart from the material equalization hopper. The secondary perforated plate is fixedly connected to the rotating shaft, and its outer periphery is clearance-fitted with the inner wall of the crucible. The drive motor drives the primary scraper and the secondary perforated plate via the rotating shaft. The perforated plate rotates synchronously; there are multiple secondary scrapers located above the secondary perforated plate, arranged around the rotation axis, and the secondary scrapers are fixedly connected to the inner circumferential wall of the crucible via connecting rods; there are side heater groups and a bottom heater, the side heater group surrounds the bottom of the crucible and is located below the secondary perforated plate, the side heater group includes multiple levels of resistance heating rings, the multiple levels of resistance heating rings are arranged at intervals in the vertical direction, each level of resistance heating ring is independently controlled, and the bottom heater is located at the bottom of the crucible.

[0007] The high-purity silicon carbide powder synthesis apparatus according to embodiments of the present invention uses a drive motor to rotate a primary scraper and a secondary perforated plate. Simultaneously, the primary scraper cooperates with the primary perforated plate, and the secondary scraper cooperates with the secondary perforated plate, enabling automated, quantitative, and uniform layering of the powder. Furthermore, the synthesis apparatus can continuously adjust the carbon-silicon ratio during the synthesis process, allowing for timely adjustments to the synthesis process without affecting subsequent synthesis. The layer-by-layer layering and synthesis methods effectively improve powder purity. The separate, layer-by-layer heating method ensures uniform heating of the powder, resulting in stable crystal structure and reducing elemental inclusions within the silicon carbide powder, thus contributing to improved silicon carbide powder purity.

[0008] In some embodiments of the present invention, the particle size of the carbon material and the silicon material is in the range of 0.3mm-0.5mm. A silicon material orifice plate is provided at the silicon material outlet, and the silicon material orifice plate is uniformly provided with a plurality of silicon material through holes, each of which has a diameter of 2.5mm-3mm. A carbon material orifice plate is provided at the carbon material outlet, and the carbon material orifice plate is uniformly provided with a plurality of carbon material through holes, each of which has a diameter of 2mm-2.5mm.

[0009] In some embodiments of the present invention, the silicon material switching door includes a first motor, a first telescopic mechanism, and a first door body. The first motor is connected to the left side wall of the crucible, and the first motor is connected to the first telescopic mechanism to drive the first door body to move in the left-right direction. The first door body is uniformly provided with a plurality of first through holes, the diameter of which is equal to the diameter of the silicon material through hole. The carbon material switching door includes a second motor, a second telescopic mechanism, and a second door body. The second motor is connected to the right side wall of the crucible, and the second motor is connected to the second telescopic mechanism to drive the second door body to move in the left-right direction. The second door body is uniformly provided with a plurality of second through holes, the diameter of which is equal to the diameter of the carbon material through hole.

[0010] In some embodiments of the present invention, the primary porous plate is uniformly provided with a plurality of primary holes, the diameter of the primary holes being 1mm-1.5mm, and the spacing between two adjacent primary holes being 0.3mm-0.5mm; the secondary porous plate is uniformly provided with a plurality of secondary holes, the diameter of the secondary holes being 1mm-1.5mm, and the spacing between two adjacent secondary holes being 0.3mm-0.5mm.

[0011] In some embodiments of the present invention, the secondary porous plate extends obliquely downward in the direction from the center to the edge of the secondary porous plate, and the angle between the secondary porous plate and the rotation axis is α, where α satisfies: 55°≤α≤70°.

[0012] In some embodiments of the present invention, the synthesis apparatus further includes: a growth chamber, wherein the crucible is located within the growth chamber; a silicon material transfer pipe, wherein the silicon material transfer pipe passes through the growth chamber and its outlet is connected to the silicon material zone; and a carbon material transfer pipe, wherein the carbon material transfer pipe passes through the growth chamber and its outlet is connected to the carbon material zone.

[0013] In some embodiments of the present invention, the synthesis apparatus further includes: a tray, which is movably disposed at the bottom of the crucible and has a clearance notch suitable for avoiding the rotation axis; and two weighing units, which are symmetrically arranged about the rotation axis and each weighing unit is connected to the tray via a support rod.

[0014] In some embodiments of the present invention, the synthesis apparatus further includes: a first argon gas channel, which is connected to the silicon material zone and is provided with a first flow control valve; and a second argon gas channel, which is connected to the carbon material zone and is provided with a second flow control valve.

[0015] In some embodiments of the present invention, the synthesis apparatus further includes: a control unit, which is communicatively connected to the bottom heater, the side heater group, the drive motor, the silicon material switch gate, the carbon material switch gate, the first flow control valve, and the second flow control valve. The multi-stage resistance heating ring is divided into a bottom heating ring group and a multi-stage gradient heating ring. The control unit is configured to: S1: Before synthesizing the silicon carbide powder, the control unit controls the first flow control valve and the second flow control valve to open to introduce argon gas; S2: After a preset time of argon gas introduction, the control unit controls the bottom heater temperature to be heated to 1900℃-2000℃, and simultaneously controls the bottom heating ring group to be heated to 1850-1900℃; S3: Heating the bottom heater and the bottom heating ring group for 3 hours. After -5 hours, the control unit controls the rotating shaft to rotate via the drive motor, thereby driving the primary scraper and the secondary perforated plate to rotate at a speed of 0.2 rad / s - 1 rad / s; S4: After the drive motor has been working for 2 minutes, the control unit controls the silicon material switch to open the silicon material outlet and controls the carbon material switch to close the carbon material outlet and maintain this for 5 minutes - 10 minutes. Then, the control unit controls the silicon material switch to close the silicon material outlet and controls the carbon material switch to open the carbon material outlet and maintain this for 5 minutes - 10 minutes. This process is repeated a preset number of times so that the silicon material and the carbon material are laid down layer by layer from the primary perforated plate. At the same time, after the drive motor has been working for 2 minutes, the control unit controls the gradient heating ring to open one level every 1 hour until all the multiple levels of the gradient heating ring are opened.

[0016] In some embodiments of the present invention, the control unit is configured to: in step S4, the control unit obtains the amount of powder falling per unit time based on the values ​​of the weighing unit and the timer, and controls the flow rate of the first flow control valve and the second flow control valve based on the amount of powder falling per unit time.

[0017] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a synthesis apparatus according to an embodiment of the present invention, wherein a first switch door closes the silicon material outlet and a second switch door closes the carbon material outlet;

[0019] Figure 2 yes Figure 1 Enlarged view of point A in the middle:

[0020] Figure 3 This is a top view of a hopper and a partition plate according to an embodiment of the present invention;

[0021] Figure 4 This is a schematic diagram of the structure of the first gate and the second gate according to an embodiment of the present invention;

[0022] Figure 5 This is a schematic diagram of a synthesis apparatus according to an embodiment of the present invention, wherein a first switch door opens the silicon material outlet and a second switch door closes the carbon material outlet;

[0023] Figure 6 yes Figure 5 Enlarged view of point B in the middle;

[0024] Figure 7 yes Figure 5 Enlarged view of point C in the middle;

[0025] Figure 8 This is a schematic diagram of a synthesis apparatus according to an embodiment of the present invention, wherein a first switch door closes the silicon material outlet and a second switch door opens the silicon material outlet;

[0026] Figure 9 yes Figure 8 Enlarged view of point D in the middle;

[0027] Figure 10 This is an XRD analysis diagram of silicon carbide powder synthesized by a synthesis apparatus according to an embodiment of the present invention.

[0028] Figure label:

[0029] Synthesis apparatus 100;

[0030] Crucible 10; Synthesis area 11;

[0031] 20. Material hopper; vertical partition plate; silicon material zone; silicon material outlet; silicon material perforated plate; silicon material through hole; carbon material zone; carbon material outlet; carbon material perforated plate; carbon material through hole; carbon material through hole;

[0032] Silicon material switch door 31; first motor 311; first telescopic mechanism 312; first door body 313; first through hole 3131;

[0033] Carbon material switch door 32; second motor 321; second telescopic mechanism 322; second door body 323; second through hole 3231;

[0034] 40. Material distribution bin; 41. Primary perforated plate; 411. Primary hole; 42. Primary scraper; 43. First clearance hole; 44. Second clearance hole;

[0035] Drive motor 50; Rotating shaft 51; Secondary perforated plate 52; Secondary hole 521;

[0036] Secondary scraper 70; connecting rod 71;

[0037] Side heater assembly 81; bottom heating ring assembly 811; gradient heating ring 812; bottom heater 82;

[0038] Growth chamber 91; Quartz tube 911; Silicon material transfer tube 92; Carbon material transfer tube 93; Support plate 94; Circumvention notch 941; Weighing unit 95; Support rod 96; First argon gas channel 97; First flow control valve 971; Second argon gas channel 98; Second flow control valve 981;

[0039] Silicon material 200; Carbon material 300. Detailed Implementation

[0040] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0041] The following disclosure provides numerous different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. Additionally, examples of various specific processes and materials are provided in this invention; however, those skilled in the art will recognize the applicability of other processes and / or the use of other materials.

[0042] The following is for reference. Figures 1-10 An apparatus 100 for synthesizing high-purity silicon carbide powder according to an embodiment of the present invention is described.

[0043] Reference Figure 1 and Figure 2 As shown, the high-purity silicon carbide powder synthesis apparatus 100 according to an embodiment of the present invention includes: a crucible 10, a hopper 20, a silicon material switch door 31, a carbon material switch door 32, a drive motor 50, a rotating shaft 51, a primary scraper 42, a secondary perforated plate 52, a side heater group 81, and a bottom heater 82.

[0044] Reference Figure 1 and Figure 2 As shown, the hopper 20 is located inside the crucible 10 and fixed to the top of the crucible 10. A loading area is defined between the hopper 20 and the crucible 10. A dividing vertical plate 21 is provided in the loading area, which divides the loading area into a silicon material area 22 and a carbon material area 23 that are spaced apart in the left and right directions. The bottom of the silicon material area 22 has a silicon material outlet 221, and the bottom of the carbon material area 23 has a carbon material outlet 231.

[0045] For example, such as Figure 2 and Figure 3 As shown, the hopper 20 is made of graphite and is funnel-shaped. The open end of the top of the hopper 20 is connected to the inner top wall of the crucible 10. The dividing vertical plate 21 is vertically arranged in the middle of the equalization hopper 40, and the front and rear ends of the dividing vertical plate 21 are connected to the inner peripheral wall of the hopper 20 (see reference). Figure 3 The silicon material zone 22 and the carbon material zone 23 have the same volume, and the silicon material outlet 221 and the carbon material outlet 231 have the same shape and area.

[0046] Reference Figure 1 and Figure 2As shown, the silicon material switch door 31 is located at the silicon material outlet 221, and is used to open or close the silicon material outlet 221. The carbon material switch door 32 is located at the carbon material outlet 231, and is used to open or close the carbon material outlet 231. It should be noted that the silicon material switch door 31 and the carbon material switch door 32 transmit signals to the control unit of the synthesis device 100, and the silicon material switch door 31 and the carbon material switch door 32 are controlled independently. It can be understood that by setting separate silicon material zones 22 and carbon material zones 23 in the silo 20, the traditional process of pre-mixing silicon and carbon materials is not required, which can save mixing time and avoid the introduction of impurities.

[0047] Reference Figure 1 and Figure 2 As shown, the uniform material hopper 40 is located below the hopper 20. The bottom of the uniform material hopper 40 is equipped with a perforated plate 41. When the silicon material switch door 31 opens the silicon material outlet 221 and the carbon material switch door 32 closes the carbon material outlet 231 (refer to...) Figure 6 Only silicon material 200 falls into the equalization silo 40 through silicon material outlet 221. When silicon material switch door 31 closes carbon material outlet 231 and carbon material switch door 32 opens carbon material outlet 231, only carbon material 300 falls into the equalization silo 40 through carbon material outlet 231.

[0048] Therefore, the laying sequence and amount of silicon material 200 and carbon material 300 can be controlled by controlling the opening sequence and opening time of silicon material switch 31 and carbon material switch 32. For example, the control unit can control silicon material switch 31 to open silicon material outlet 221, control carbon material switch 32 to close carbon material outlet 231 and maintain this for 5-10 minutes, then control silicon material switch 31 to close silicon material outlet 221, control carbon material switch 32 to open carbon material outlet 231 and maintain this for 5-10 minutes, and repeat this process a preset number of times to ensure that silicon material 200 and carbon material 300 are laid down layer by layer from the primary porous plate 41 (refer to...). Figure 8 ).

[0049] Reference Figure 1 and Figure 2 As shown, the drive motor 50 is located below the crucible 10. For example, the drive motor 50 is located below the growth chamber 91 described below. The rotating shaft 51 passes through the crucible 10 from the bottom. The output end of the drive motor 50 is connected to the rotating shaft 51. The top end of the rotating shaft 51 is provided with a primary scraper 42, which is located in the equalization bin 40.

[0050] Reference Figure 1 and Figure 2 As shown, the secondary perforated plate 52 is located below and spaced apart from the material distribution bin 40, for example, referring to... Figure 8As shown, the vertical distance L between the secondary porous plate 52 and the uniform material hopper 40 can be 30mm-50mm. In other words, the vertical distance L between the secondary porous plate 52 and the uniform material hopper 40 can be any value between 30mm and 50mm. It can be understood that the bottom surface of the secondary porous plate 52 and the crucible 10 define the synthesis area 11 of silicon carbide powder. By setting the value of L within a reasonable range and cooperating with the rotation of the rotating shaft 51, it is beneficial to control the amount of powder falling onto the secondary porous plate 52 within the set range, thereby improving the uniformity of the powder in the synthesis area 11.

[0051] Reference Figure 1 As shown, the secondary porous plate 52 is fixedly connected to the rotating shaft 51. The outer periphery of the secondary porous plate 52 is in clearance fit with the inner peripheral wall of the crucible 10. For example, the gap between the outer periphery of the secondary porous plate 52 and the inner peripheral wall of the crucible 10 can be 0.2mm-0.3mm. The drive motor 50 drives the primary scraper 42 and the secondary porous plate 52 to rotate synchronously through the rotating shaft 51. There are multiple secondary scrapers 70 located above the secondary porous plate 52. The multiple secondary scrapers 70 are arranged around the rotating shaft 51. The secondary scrapers 70 are fixedly connected to the inner peripheral wall of the crucible 10 through the connecting rod 71. It can be understood that by driving the primary scraper 42 and the secondary porous plate 52 to rotate through the drive motor 50, the falling powder falls evenly through the primary porous plate 41 and the second multilayer plate to the synthesis area 11 at the bottom of the crucible 10. The falling powder is laid layer by layer in the synthesis area 11, which can form a multilayer stacked powder layout with a bottom silicon material 200 and an upper carbon material 300.

[0052] Reference Figure 1 As shown, the side heater assembly 81 surrounds the bottom of the crucible 10 and is located below the secondary porous plate 52. The side heater assembly 81 includes a multi-stage resistance heating ring, which is arranged at intervals in the vertical direction. Each stage of the resistance heating ring is independently controlled. The bottom heater 82 is located at the bottom of the crucible 10.

[0053] Optionally, such as Figure 1As shown, the side heater assembly 81 may include ten levels of resistance heating rings. These ten levels of resistance heating rings are divided into a bottom heating ring assembly 811 and multi-level gradient heating rings 812. The bottom heating ring assembly 811 includes first to fourth levels of resistance heating rings at the bottom, and six levels of resistance heating rings at the top, which are gradient heating rings 812. Each level of resistance heating ring is independently controlled by the control system. After the reaction begins, one level is activated every hour. The activation temperature of the next higher-level gradient heating ring 812 is 8°C-10°C lower than the temperature of the bottom heating ring assembly 811. For example, the heating temperature of the bottom heating ring group 811 is 1900 degrees Celsius. The opening temperature of the next-level gradient heating ring 812 is 10 degrees Celsius lower than that of the bottom heating ring group 811. That is to say, the opening temperature of the next-level gradient heating ring 812 (the fifth resistance heating ring from the bottom) is 1890 degrees Celsius, the next-level gradient heating ring 812 (the 10th resistance heating ring from the bottom) is 1880 degrees Celsius, and so on, with the opening temperature of the topmost gradient heating ring 812 being 1840 degrees Celsius. It can be understood that the main purpose of this design is to ensure a suitable temperature gradient inside the crucible 10, so that the bottom temperature of the synthesis region 11 of the crucible 10 is higher than that of the top. Under the action of this temperature gradient, the gas after the silicon material 200 sublimates is provided with power, causing the silicon material 200 to move upward after sublimation, thereby contacting the carbon material 300 to react.

[0054] Understandably, by using the silicon material switching gate 31 and the carbon material switching gate 32 in combination, the silicon material 200 and carbon material 300 can be controlled to fall into the homogenizing hopper 40 in batches, with the silicon material 200 falling first and the carbon material 300 falling later, and so on. At the same time, due to the rotation of the primary scraper 42 and the secondary perforated plate 52, the falling powder falls evenly into the synthesis area 11 at the bottom of the crucible 10 through the primary perforated plate 41 and the secondary perforated plate 52. The falling powder is laid layer by layer in the synthesis area 11, forming a multi-layer powder layout with a lower layer of silicon material 200 and an upper layer of carbon material 300. While the powder is being laid, the side heater group 81 gradually heats from the bottom to the top, so that the layered powder, together with the independently partitioned multi-level resistance heating ring, achieves layered synthesis, thereby ensuring that the powder is heated evenly and producing a stable crystal form of the powder.

[0055] Compared to the traditional method of uniformly mixing silicon and carbon materials and then heating, the high-purity silicon carbide powder synthesis apparatus 100 of this embodiment of the invention, during the synthesis of silicon carbide powder, utilizes the low melting point of silicon material 200. The sublimated silicon vapor rises and reacts with the upper-layered carbon material 300, generating silicon carbide powder in the area where carbon material 300 is present. This significantly optimizes the purity of the synthesized powder, thereby increasing the silicon carbide product content and reducing impurity concentration. Furthermore, the uniform synthesis temperature in the synthesis region 11 and the layered synthesis improve the ratio of homogeneous crystals, which is beneficial for improving the synthesis quality of silicon carbide powder. In addition, the synthesis apparatus 100 can continuously adjust the carbon-silicon ratio during the synthesis process, allowing for timely adjustments to the synthesis process without affecting subsequent synthesis.

[0056] In view of this, the high-purity silicon carbide powder synthesis apparatus 100 according to the present invention drives the primary scraper 42 and the secondary porous plate 52 to rotate via the drive motor 50. At the same time, the primary scraper 42 cooperates with the primary porous plate 41, and the secondary scraper 70 cooperates with the secondary porous plate 52, which can realize the automated quantitative layering and uniform spreading of powder. Meanwhile, the synthesis apparatus 100 can continuously adjust the carbon-silicon ratio during the synthesis process, adjust the synthesis process in a timely manner as needed, and will not affect subsequent synthesis. Moreover, the method of layer-by-layer spreading and layered synthesis can effectively improve the purity of powder. The separate layer-by-layer heating method ensures uniform heating of powder, resulting in stable crystal form of powder. At the same time, silicon vapor can sublimate normally and will not form a carbon coating shell on the surface of silicon material 200, resulting in a more complete reaction.

[0057] In some embodiments of the present invention, reference is made to... Figure 1 As shown, the particle size of carbon material 300 and silicon material 200 both range from 0.3mm to 0.5mm. In other words, silicon material 200 and carbon material 300 have the same particle size, and the particle size can take any value between 0.3mm and 0.5mm.

[0058] Reference Figure 2 As shown, a silicon material outlet 221 is provided with a silicon material perforation plate 222, and the silicon material perforation plate 222 is uniformly provided with a plurality of silicon material through holes 223. The diameter of each silicon material through hole 223 is 2.5mm-3mm. For example, the diameter of the silicon material through hole 223 can be 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm or 3mm, etc. A carbon material outlet 231 is provided with a carbon material perforation plate 232, and the carbon material perforation plate 232 is uniformly provided with a plurality of carbon material through holes 233. The diameter of the carbon material through holes 233 is 2mm-2.5mm. For example, the diameter of the carbon material through holes 233 can be 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm or 2.5mm.

[0059] It is understandable that by making the particle size of carbon material 300 and silicon material 200 the same, and by making the diameter of each silicon material through-hole 223 2.5mm-3mm and the diameter of the carbon material through-hole 233 2mm-2.5mm, combined with controlling the time for each fall of carbon material 300 and silicon material 200 to be the same, it is possible to control the molar ratio of the lower silicon material 200 and the upper carbon material 300 to be maintained at 1-1.1, that is, the silicon-carbon molar ratio is relatively high. This allows for a higher silicon content in the atmosphere during synthesis, which can compensate for silicon loss (because silicon has a low melting point and is easily sublimated, some silicon is easily carried away by the carrier gas), which is beneficial to further improve the synthesis purity of silicon carbide.

[0060] In some embodiments of the present invention, reference is made to... Figure 5 and Figure 6 As shown, the silicon material switching door 31 includes a first motor 311, a first telescopic mechanism 312, and a first door body 313. The first motor 311 is connected to the left side wall of the crucible 10. The first motor 311 is connected to the first telescopic mechanism 312 to drive the first door body 313 to move in the left-right direction. The first door body 313 is uniformly provided with a plurality of first through holes 3131, the diameter of which is equal to the diameter of the silicon material through hole 223. The carbon material switching door 32 includes a second motor 321, a second telescopic mechanism 322, and a second door body 323. The second motor 321 is connected to the right side wall of the crucible 10. The second motor 321 is connected to the second telescopic mechanism 322 to drive the second door body 323 to move in the left-right direction. The second door body 323 is uniformly provided with a plurality of second through holes 3231, the diameter of which is equal to the diameter of the carbon material through hole 233. For example, the first telescopic mechanism 312 and the second telescopic mechanism 322 are both linearly telescopic screw mechanisms. Before the synthesis begins, refer to... Figure 2 As shown, the first through hole 3131 and the silicon material through hole 223 are completely misaligned in the vertical direction, and the second through hole 3231 and the carbon material through hole 233 are completely misaligned in the vertical direction.

[0061] It is understandable that by setting the first motor 311 and the second motor 321, it is convenient to achieve independent control of the first gate 313 and the second gate 323. By setting multiple first through holes 3131 in the first gate 313 and multiple second through holes 3231 in the second gate 323, the first gate 313 only needs to move a very small distance to open and close the silicon material through hole 223, and the second gate 323 only needs to move a very small distance to open and close the carbon material through hole 233. This helps to reduce the energy consumption of the first motor 311 and the second motor 321, and the short stroke also helps to reduce energy consumption.

[0062] Optionally, refer to Figure 6As shown, the left and right sides of the equalization bin 40 are respectively provided with a first clearance hole 43 and a second clearance hole 44, and the first door body 313 and the second door body 323 are both formed into rectangular plates (refer to...). Figure 4 The first door 313 is movably disposed in the material distribution bin 40 through the first clearance hole 43, and the second door 323 is movably disposed in the material distribution bin 40 through the second clearance hole 44. Thus, the structure is compact and easy to implement.

[0063] In some embodiments of the present invention, reference is made to... Figure 2 As shown, the primary perforated plate 41 is uniformly provided with a plurality of primary holes 411, the diameter of which is 1mm-1.5mm. For example, as shown... Figure 2 As shown, the diameter of the primary hole 411 can be 1mm, 1.2mm, 1.3mm, 1.4mm or 1.5mm, etc., and the primary hole 411 can be formed as a vertical hole.

[0064] Optionally, such as Figure 1 As shown, the spacing between two adjacent primary holes 411 is 0.3mm-0.5mm. For example, the spacing between two adjacent primary holes 411 can be 0.3mm, 0.4mm, or 0.5mm. It can be understood that by making the diameter of the primary holes 411 1mm-1.5mm and the spacing between two adjacent primary holes 411 0.3mm-0.5mm, the size of the primary holes 411 can be appropriate and the arrangement can be dense. At the same time, in conjunction with the primary scraper 42, it is beneficial to ensure that the powder flows out evenly through the primary perforated plate 41.

[0065] Reference Figure 2 As shown, the secondary perforated plate 52 is uniformly provided with a plurality of secondary holes 521. The diameter of the secondary holes 521 is 1mm-1.5mm. For example, the diameter of the secondary holes 521 can be 1mm, 1.2mm, 1.3mm, 1.4mm or 1.5mm, etc. The secondary holes 521 can be formed as vertical holes.

[0066] Optionally, refer to Figure 2 As shown, the spacing between adjacent secondary holes 521 is 0.3mm-0.5mm. For example, the spacing between two adjacent secondary holes 521 can be 0.3mm, 0.4mm, or 0.5mm. It can be understood that by making the diameter of the secondary holes 521 1mm-1.5mm and the spacing between two adjacent secondary holes 521 0.3mm-0.5mm, the size of the secondary holes 521 can be appropriate and the arrangement can be dense. At the same time, in conjunction with the secondary scraper 70, it is beneficial to ensure that the powder flows out of the secondary perforated plate 52 evenly.

[0067] In some embodiments of the present invention, reference is made to... Figure 5 and Figure 7As shown, the secondary porous plate 52 extends downwards at an angle from its center to its edge. The angle between the secondary porous plate 52 and the rotating shaft 51 is α, which satisfies the condition: 55° ≤ α ≤ 70°. For example, α can take values ​​of 55°, 58°, 60°, 62°, 66°, or 70°. It is understood that by ensuring the angle α between the secondary porous plate 52 and the rotating shaft 51 is between 55° and 70°, it is possible to avoid an excessively large value of α, which helps ensure the powder disperses evenly downwards; conversely, it is possible to avoid an excessively small value of α, which helps prevent the powder from concentrating at the bottom.

[0068] In some embodiments of the present invention, reference is made to... Figure 1 As shown, the synthesis apparatus 100 further includes: a growth chamber 91, a silicon material transfer pipe 92, and a carbon material transfer pipe 93. The crucible 10 is located inside the growth chamber 91. The silicon material transfer pipe 92 passes through the growth chamber 91, and its outlet is connected to the silicon material zone 22. The carbon material transfer pipe 93 passes through the growth chamber 91, and its outlet is connected to the carbon material zone 23. The inlet of the silicon material transfer pipe 92 is connected to the silicon material source. A silicon material control valve is provided between the silicon material transfer pipe 92 and the silicon material source to control whether the silicon material source feeds into the silicon material transfer pipe 92. The carbon material transfer pipe 93 is connected to the carbon material source, and a carbon material regulating valve is provided between the carbon material transfer pipe 93 and the carbon material source to control whether the carbon material source feeds into the carbon material transfer pipe. It is understandable that by setting up silicon material transfer pipe 92 and carbon material transfer pipe 93, continuous feeding can be achieved during the synthesis process, which is beneficial to increasing the amount of silicon carbide powder synthesized. Optionally, the synthesis apparatus 100 also includes a quartz tube 911, with the crucible 10 located inside the quartz tube 911, thereby improving the heat preservation effect on the crucible 10.

[0069] In some embodiments of the present invention, the synthesis apparatus 100 further includes a tray 94 and a weighing unit 95. The tray 94 is movably disposed at the bottom of the crucible 10 and has a clearance notch 941 suitable for avoiding the rotation shaft 51. There are two weighing units 95, which are symmetrically arranged about the rotation shaft 51. Each weighing unit 95 is connected to the tray 94 via a support rod 96. The weighing unit 95 is suitable for measuring the weight of the powder on the tray 94 in real time. It can be understood that during the synthesis process, the weighing unit 95 can work with the timer of the control unit to obtain the weight of the powder falling onto the tray 94 per unit time, thereby determining whether the powder falling speed is too fast or too slow. Technicians can operate and adjust in a timely manner, which is beneficial to further improve the synthesis quality of silicon carbide powder.

[0070] In some embodiments of the present invention, reference is made to... Figure 1As shown, the synthesis apparatus 100 further includes: a first argon gas channel 97 and a second argon gas channel 98. The first argon gas channel 97 is connected to the silicon material zone 22 and is equipped with a first flow control valve 971. The second argon gas channel 98 is connected to the carbon material zone 23 and is equipped with a second flow control valve 981. It can be understood that by setting the first flow control valve 971 and the second flow control valve 981, when the weighing unit 95 determines that the falling speed of the powder per unit time is too slow, the flow rates of the first flow control valve 971 and the second flow control valve 981 can be appropriately increased; when the weighing unit 95 determines that the falling speed of the powder per unit time is too fast, the flow rates of the first flow control valve 971 and the second flow control valve 981 can be appropriately decreased. This allows the falling speed of the powder to be controlled within a reasonable range, which is beneficial to ensuring the synthesis purity of the silicon carbide powder.

[0071] In some embodiments of the present invention, the synthesis apparatus 100 further includes: a control unit, which is communicatively connected to the bottom heater 82, the side heater group 81, the drive motor 50, the silicon material switch 31, the carbon material switch 32, the first flow control valve 971, and the second flow control valve 981. The multi-stage resistance heating ring is divided into a bottom heating ring group 811 and a multi-stage gradient heating ring 812. The control unit is configured to: S1: Before synthesizing silicon carbide powder, the control unit controls the first flow control valve 971 and the second flow control valve 981 to open to introduce argon gas; S2: After a preset time of argon gas introduction, the control unit controls the bottom heater 82 to heat to 1900℃-2000℃, and simultaneously controls the bottom heating ring group 811 to heat to 1850-1900℃; S3: Heat the bottom heater 82 and the bottom heating ring group 811 for 3 hours. After -5 hours, the control unit controls the rotating shaft 51 to rotate via the drive motor 50, thereby driving the primary scraper 42 and the secondary perforated plate 52 to rotate at a speed of 0.2 rad / s-1 rad / s; S4: After the drive motor 50 has been working for 2 minutes, the control unit controls the silicon material switch door 31 to open the silicon material outlet 221 and controls the carbon material switch door 32 to close the carbon material outlet 231 and maintain this for 5 minutes-10 minutes. Then, the control unit controls the silicon material switch door 31 to close the silicon material outlet 221 and controls the carbon material switch door 32 to open the carbon material outlet 231 and maintain this for 5 minutes-10 minutes. This process is repeated a preset number of times so that the silicon material 200 and carbon material 300 are laid down layer by layer from the primary perforated plate 41. At the same time, after the drive motor 50 has been working for 2 minutes, the control unit controls the gradient heating ring 812 to open one level every 1 hour until all the multi-level gradient heating rings 812 are opened.

[0072] Understandably, by driving the primary scraper 42 and the secondary perforated plate 52 to rotate via the drive motor 50, and with the primary scraper 42 cooperating with the primary perforated plate 41 and the secondary scraper 70 cooperating with the secondary perforated plate 52, automated, quantitative, and uniform layering of powder can be achieved. Furthermore, the layer-by-layer layering and synthesis method effectively improves powder purity. The separate, layer-by-layer heating method ensures uniform heating of the powder, resulting in stable crystal structure. Simultaneously, silicon vapor can sublimate normally, preventing the formation of a coating on the surface of the silicon material 200, thus ensuring a more complete reaction.

[0073] In some embodiments of the present invention, the control unit is configured to: in step S4, control the flow rates of the first flow control valve 971 and the second flow control valve 981 based on the amount of powder falling per unit time fed back by the weighing device. It is understood that by setting the first flow control valve 971 and the second flow control valve 981, when the weighing unit 95 determines that the powder falling speed per unit time is too slow, the flow rates of the first flow control valve 971 and the second flow control valve 981 can be appropriately increased; when the weighing unit 95 determines that the powder falling speed per unit time is too fast, the flow rates of the first flow control valve 971 and the second flow control valve 981 can be appropriately decreased. This allows the powder falling speed to be controlled within a reasonable range, which is beneficial for ensuring the synthesis purity of silicon carbide powder.

[0074] For example, in some specific embodiments of the present invention, both carbon material 300 and silicon material 200 have a particle size of 0.3mm-0.5mm, the diameter of silicon material through-hole 223 is selected as 2.5mm, the diameter of the first through-hole 3131 is selected as 2.5mm, the diameter of carbon material through-hole 233 is selected as 2mm, the diameter of the second through-hole 3231 is selected as 2mm, the diameter of the primary hole 411 is 1.2mm, the spacing between two adjacent primary holes 411 is 0.4mm, the diameter of the secondary hole 521 is 1.2mm, the spacing between two adjacent secondary holes 521 is 0.4mm, the angle α between the secondary perforated plate 52 and the rotating shaft 51 is selected as 58°, and the side heater assembly 81 includes: ten The bottom heating ring group 811 includes a bottom first-stage resistance heating ring, a second-stage resistance heating ring, a third-stage resistance heating ring, and a fourth-stage resistance heating ring. The heating temperature of the bottom heating ring group 811 is 1900 degrees Celsius. The opening temperature of the next-level gradient heating ring 812 is 10 degrees Celsius lower than that of the bottom heating ring group 811. That is to say, the opening temperature of the next-level gradient heating ring 812 (the fifth resistance heating ring from the bottom) is 1890 degrees Celsius, the next-level gradient heating ring 812 (the 1st resistance heating ring from the bottom) is 1880 degrees Celsius, and so on, with the opening temperature of the topmost gradient heating ring 812 being 1840 degrees Celsius.

[0075] The control system is set as follows: S1: Before synthesizing silicon carbide powder, the control unit controls the first flow control valve 971 and the second flow control valve 981 to open, and controls the flow rate to about 100 sccm to introduce argon gas. It also controls the silicon material switch gate 31 to close multiple silicon material through holes 223 and controls the carbon material switch gate 32 to close multiple carbon material through holes 233. At this time, silicon material 200 and carbon material 300 cannot flow to the homogenizing bin 40, but argon gas can flow to the growth area of ​​the crucible 10 through the gap between the homogenizing bin 40 and the crucible 10.

[0076] S2: After argon gas is introduced for a preset time to allow the pressure inside the growth chamber 91 to reach 150 mbar-200 mbar, the control unit controls the bottom heater 82 to heat to 1950°C, and simultaneously controls the bottom heating ring assembly 811 to heat to 1900°C.

[0077] S3: After the bottom heater 82 and the bottom heating ring group 811 have been heated for 4 hours, the control unit controls the rotating shaft 51 to rotate through the drive motor 50, so as to drive the first-stage scraper 42 and the second-stage perforated plate 52 to rotate at a speed of 0.5 rad / s.

[0078] S4: After the drive motor 50 operates for 2 minutes, the control unit controls the silicon material switch door 31 to open the silicon material outlet 221 and controls the carbon material switch door 32 to close the carbon material outlet 231 and maintain this for 8 minutes. Then, the control unit controls the silicon material switch door 31 to close the silicon material outlet 221 and controls the carbon material switch door 32 to open the carbon material outlet 231 and maintain this for 8 minutes. This process is repeated a preset number of times to ensure that the silicon material 200 and carbon material 300 are laid down layer by layer from the first-stage porous plate 41. At the same time, after the drive motor 50 operates for 2 minutes, the control unit controls the gradient heating ring 812 to open one level every 1 hour until all ten gradient heating rings 812 are opened.

[0079] Furthermore, when the silicon material switch gate 31 opens multiple silicon material through holes 223 and the carbon material switch gate 32 closes multiple carbon material through holes 233, if the weighing unit 95 detects that the weight of the powder falling per unit time is less than 7g / min, the flow rate of argon gas in the first flow control valve 971 is controlled to a preset high speed (e.g., 160sccm); if the weighing unit 95 detects that the weight of the powder falling per unit time is greater than 7g / min, the flow rate of argon gas in the first flow control valve 971 is controlled to a preset low speed (e.g., 50sccm).

[0080] When the silicon material switching gate 31 closes multiple silicon material through-holes 223 and the carbon material switching gate 32 opens multiple carbon material through-holes 233, if the weighing unit 95 detects that the weight of powder falling per unit time is less than 3 g / min, the flow rate of argon gas in the second flow control valve 981 is controlled to a preset high speed (e.g., 130 sccm). If the weighing unit 95 detects that the weight of powder falling per unit time is greater than 3 g / min, the flow rate of argon gas in the second flow control valve 981 is controlled to a preset low speed (e.g., 60 sccm). This helps to maintain the molar ratio of the lower silicon material 200 and the upper carbon material 300 at 1-1.1, i.e., a higher silicon-carbon molar ratio. This allows for a higher silicon content in the atmosphere during synthesis, which can compensate for silicon loss and further improve the purity of silicon carbide synthesis.

[0081] After numerous experiments by the inventors, the particle size of the silicon carbide powder synthesized in the embodiments of this invention is basically maintained between 0.5-1.8 mm, with a proportion exceeding 80%. The normal crystal growth process requires silicon carbide powder with a particle size between 0.45-2.5 mm, i.e., between 8 mesh and 40 mesh. The experimental results meet the requirements. In contrast, the yield of traditionally synthesized silicon carbide powder is approximately 30%-40%, with the remaining particle size falling outside the usable range. Therefore, the synthesis apparatus 100 of this invention can significantly increase the usable amount and yield of silicon carbide powder. Furthermore, purity analysis shows that the purity of the powder synthesized by the synthesis apparatus 100 of this invention can reach 6N (99.9999%), fully meeting the requirements for silicon carbide crystal growth.

[0082] Specifically, refer to Figure 10 As shown, XRD analysis revealed that the highest diffraction peak of the synthesized product from the synthesis apparatus 100 in this embodiment of the invention is SiC, indicating that the raw materials reacted completely and the product is essentially SiC.

[0083] In addition to XRD analysis, GDMS data can reflect the purity of silicon carbide powder. Detailed data are shown in the table below.

[0084]

[0085]

[0086] The purity of the GDMS-detected data was 99.999934%.

[0087] In summary, as can be seen from the XRD and GDMS detection data, the synthesis apparatus 100 according to the embodiment of the present invention can effectively control the reaction product to be high-purity silicon carbide powder. Compared with traditional methods, the yield of silicon carbide powder produced by the synthesis apparatus 100 according to the embodiment of the present invention can be greatly improved, and it is beneficial to avoid the generation of silicon carbide powder with excessively large or small particle sizes.

[0088] Other configurations and operations of the apparatus 100 for synthesizing high-purity silicon carbide powder according to embodiments of the present invention are known to those skilled in the art and will not be described in detail here.

[0089] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0090] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0091] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0092] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0093] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0094] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. An apparatus for synthesizing high-purity silicon carbide powder, characterized in that, include: crucible; A hopper is located inside the crucible and fixed to the top of the crucible. A loading area is defined between the hopper and the crucible. A dividing vertical plate is provided in the loading area, which divides the loading area into a silicon material area and a carbon material area spaced apart in the left-right direction. The bottom of the silicon material area has a silicon material outlet, and the bottom of the carbon material area has a carbon material outlet. A silicon material switch gate and a carbon material switch gate are provided. The silicon material switch gate is located at the silicon material outlet and is used to open or close the silicon material outlet. The carbon material switch gate is located at the carbon material outlet and is used to open or close the carbon material outlet. A uniform material silo is connected below the material silo. The bottom of the uniform material silo is provided with a perforated plate. When the silicon material switch door opens the silicon material outlet and the carbon material switch door closes the carbon material outlet, only the silicon material falls into the uniform material silo through the silicon material outlet. When the silicon material switch door closes the silicon material outlet and the carbon material switch door opens the carbon material outlet, only the carbon material falls into the uniform material silo through the carbon material outlet. The system includes a drive motor and a rotating shaft. The drive motor is located below the crucible, and the rotating shaft extends into the crucible from the bottom. The output end of the drive motor is connected to the rotating shaft, and a primary scraper is provided at the top of the rotating shaft. The primary scraper is located inside the equalization bin. A secondary perforated plate is located below and spaced apart from the material equalization bin. The secondary perforated plate is fixedly connected to the rotating shaft. The outer periphery of the secondary perforated plate is clearance-fitted with the inner peripheral wall of the crucible. The drive motor drives the primary scraper and the secondary perforated plate to rotate synchronously through the rotating shaft. A secondary scraper, wherein there are multiple secondary scrapers located above the secondary perforated plate, the multiple secondary scrapers are arranged around the rotating shaft, and the secondary scrapers are fixedly connected to the inner peripheral wall of the crucible by connecting rods; The crucible has a side heater assembly and a bottom heater. The side heater assembly surrounds the bottom of the crucible and is located below the secondary porous plate. The side heater assembly includes multiple levels of resistance heating rings, which are arranged at intervals in the vertical direction. Each level of resistance heating ring is independently controlled. The bottom heater is located at the bottom of the crucible.

2. The apparatus for synthesizing high-purity silicon carbide powder according to claim 1, characterized in that, The particle size of both the carbon material and the silicon material is in the range of 0.3mm-0.5mm. A silicon material orifice plate is provided at the silicon material outlet, and the silicon material orifice plate is uniformly provided with a plurality of silicon material through holes, each of which has a diameter of 2.5mm-3mm. A carbon material orifice plate is provided at the carbon material outlet, and the carbon material orifice plate is uniformly provided with a plurality of carbon material through holes, each of which has a diameter of 2mm-2.5mm.

3. The apparatus for synthesizing high-purity silicon carbide powder according to claim 2, characterized in that, The silicon material switching door includes a first motor, a first telescopic mechanism, and a first door body. The first motor is connected to the left side wall of the crucible, and the first motor is connected to the first telescopic mechanism to drive the first door body to move in the left-right direction. The first door body is uniformly provided with a plurality of first through holes, the diameter of which is equal to the diameter of the silicon material through hole. The carbon material switching door includes a second motor, a second telescopic mechanism, and a second door body. The second motor is connected to the right side wall of the crucible, and the second motor is connected to the second telescopic mechanism to drive the second door body to move in the left-right direction. The second door body is uniformly provided with a plurality of second through holes, the diameter of which is equal to the diameter of the carbon material through hole.

4. The apparatus for synthesizing high-purity silicon carbide powder according to claim 1, characterized in that, The primary perforated plate is uniformly provided with a plurality of primary holes, the diameter of which is 1mm-1.5mm and the spacing between two adjacent primary holes is 0.3mm-0.5mm. The secondary perforated plate is uniformly provided with a plurality of secondary holes, the diameter of which is 1mm-1.5mm and the spacing between two adjacent secondary holes is 0.3mm-0.5mm.

5. The apparatus for synthesizing high-purity silicon carbide powder according to claim 1, characterized in that, The secondary porous plate extends downward at an angle from its center to its edge, and the angle between the secondary porous plate and the rotation axis is α, where α satisfies: 55°≤α≤70°.

6. The apparatus for synthesizing high-purity silicon carbide powder according to claim 1, characterized in that, Also includes: A growth chamber, wherein the crucible is located within the growth chamber; A silicon material transfer pipe is installed in the growth chamber, and the outlet of the silicon material transfer pipe is connected to the silicon material zone. A carbon material transfer pipe is installed in the growth chamber, and the outlet of the carbon material transfer pipe is connected to the carbon material zone.

7. The apparatus for synthesizing high-purity silicon carbide powder according to claim 1, characterized in that, Also includes: A tray, which is movably disposed at the bottom of the crucible, is provided with a clearance notch suitable for avoiding the rotation axis; The weighing unit comprises two units, which are symmetrically arranged about the rotation axis. Each weighing unit is connected to the pallet via a support rod. The weighing unit is adapted to measure the weight of the powder on the pallet in real time.

8. The apparatus for synthesizing high-purity silicon carbide powder according to claim 7, characterized in that, Also includes: A first argon gas channel is connected to the silicon material area, and the first argon gas channel is equipped with a first flow control valve. The second argon gas channel is connected to the carbon material zone, and the second argon gas channel is equipped with a second flow control valve.

9. The apparatus for synthesizing high-purity silicon carbide powder according to claim 8, characterized in that, Also includes: The control unit is communicatively connected to the bottom heater, the side heater group, the drive motor, the silicon material switch gate, the carbon material switch gate, the first flow control valve, and the second flow control valve. The multi-stage resistance heating ring is divided into a bottom heating ring group and a multi-stage gradient heating ring. The control unit is configured as follows: S1: Before synthesizing the silicon carbide powder, the control unit controls the first flow control valve and the second flow control valve to open to introduce argon gas; S2: After a preset time of argon gas introduction, the control unit controls the bottom heater temperature to 1900℃-2000℃, and simultaneously controls the bottom heating ring assembly to 1850-1900℃. S3: After the bottom heater and the bottom heating ring assembly have been heated for 3-5 hours, the control unit controls the rotating shaft to rotate via the drive motor, thereby driving the first-stage scraper and the second-stage perforated plate to rotate at a speed of 0.2 rad / s-1 rad / s. S4: After the drive motor has been running for 2 minutes, the control unit controls the silicon material switch to open the silicon material outlet and controls the carbon material switch to close the carbon material outlet for 5-10 minutes. Then, the control unit controls the silicon material switch to close the silicon material outlet and controls the carbon material switch to open the carbon material outlet for 5-10 minutes. This process is repeated a preset number of times to ensure that the silicon material and the carbon material are laid down layer by layer from the first-stage porous plate. At the same time, after the drive motor has been running for 2 minutes, the control unit controls the gradient heating ring to open one level every 1 hour until all the gradient heating rings are opened.

10. The apparatus for synthesizing high-purity silicon carbide powder according to claim 9, characterized in that, The control unit is configured as follows: In step S4, the control unit obtains the amount of powder falling per unit time based on the values ​​of the weighing unit and the timer, and controls the flow rate of the first flow control valve and the second flow control valve based on the amount of powder falling per unit time.

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