Synthesis device and synthesis method of silicon carbide powder

Abstract

The application discloses a synthesis device and a synthesis method of silicon carbide powder, and belongs to the technical field of silicon carbide powder synthesis. The synthesis device comprises a reaction crucible, a reaction assembly and a discharging assembly. The reaction crucible defines a reaction cavity, and the bottom of the reaction crucibble is provided with a discharging port. The reaction assembly is provided with a plurality of reaction assemblies arranged in the reaction cavity, which are used for providing a reaction site and conveying the silicon carbide powder generated by the reaction to the bottom of the reaction cavity. The discharging assembly is arranged in the reaction cavity and is used for pushing the silicon carbide powder accumulated at the bottom of the reaction cavity to the discharging port. The upper part of the sidewall of the reaction crucible is provided with a first gas inlet for introducing reaction gas, and the lower part of the sidewall of the reaction crucible is provided with a second gas inlet for introducing carrier gas. The top of the reaction crucible is provided with a gas outlet. The application can reduce the problem of elemental inclusion in the silicon carbide powder, obtain high-purity silicon carbide powder, and continuously discharge the silicon carbide powder, so that the yield and efficiency are improved.

Description

Technical Field

[0001] This invention relates to the field of silicon carbide powder synthesis, and in particular to an apparatus and method for synthesizing silicon carbide powder. Background Technology

[0002] Silicon carbide, as a representative of third-generation semiconductors, plays a crucial role in fields such as new energy. One of the essential raw materials for silicon carbide crystals is silicon carbide powder, and the purity of the silicon carbide powder directly affects the quality of the 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 the raw material. However, current methods for preparing silicon carbide powder suffer from problems such as low synthesis purity, inclusions, and the inability to continuously discharge the powder. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention provides a silicon carbide powder synthesis apparatus that can reduce the problem of elemental inclusions inside silicon carbide powder, improve the purity of silicon carbide powder, and produce high-purity silicon carbide powder; at the same time, it can also perform continuous discharge, thereby improving yield and efficiency.

[0004] The present invention also proposes a method for synthesizing silicon carbide powder using the above-described synthesis apparatus.

[0005] An apparatus for synthesizing silicon carbide powder according to an embodiment of the present invention includes:

[0006] A reaction crucible, which defines a reaction chamber, and a discharge port is provided at the bottom of the reaction crucible;

[0007] The reaction assembly comprises multiple reaction assemblies disposed within the reaction chamber, which serve to provide a reaction site and transport the silicon carbide powder generated by the reaction to the bottom of the reaction chamber;

[0008] A discharge assembly is disposed inside the reaction chamber and is used to push the silicon carbide powder accumulated at the bottom of the reaction chamber to the discharge port;

[0009] The reaction crucible has a first inlet for the reaction gas to enter at the upper part of its sidewall, and a second inlet for the carrier gas to enter at the lower part of its sidewall; the top of the reaction crucible has an outlet.

[0010] According to the silicon carbide powder synthesis apparatus of the present invention, silicon carbide powder can be prepared using a gas containing carbon and silicon atoms as a reaction source. Specifically, the reaction gas is introduced into a reaction crucible, and silicon carbide powder is synthesized by chemical decomposition and synthesis deposition at high temperature. The synthesized silicon carbide powder is deposited on the reaction assembly and transported to the bottom of the reaction chamber. When the silicon carbide powder at the bottom reaches a preset value, the discharge assembly pushes the accumulated silicon carbide powder at the bottom to the outside of the reaction crucible through the discharge port. The reaction and discharge can be carried out simultaneously, realizing uninterrupted production and improving efficiency. At the same time, the gas synthesis method is less likely to introduce solid particulate impurities, which can greatly improve the purity of the final silicon carbide powder. This method can control the purity of silicon carbide powder between 99.999% and 99.9999%.

[0011] In some embodiments of the present invention, the reaction component includes:

[0012] A reaction rod, arranged within the reaction chamber, is used to provide a reaction site;

[0013] A collector is disposed on the reaction rod and is reciprocating along the axial direction of the reaction rod to peel off the silicon carbide powder deposited on the reaction rod.

[0014] A drive mechanism connected to the collector to drive the movement of the collector on the reaction rod.

[0015] In some embodiments of the present invention, the reaction rod is provided with a silicon carbide layer.

[0016] In some embodiments of the present invention, the driving mechanism includes:

[0017] A first screw is disposed inside the reaction chamber and is rotatably mounted on the reaction crucible;

[0018] A first motor is located outside the reaction crucible and connected to the first screw.

[0019] A connecting plate is disposed on the first screw and can reciprocate along the axial direction of the first screw as the first screw rotates;

[0020] The first screw is arranged parallel to the reaction rod; the connecting plate is connected to the collector.

[0021] In some embodiments of the present invention, the horizontal cross-section of the reaction crucible is circular, the discharge port is arranged from the center to the circumference of the bottom wall of the reaction crucible, and the discharge assembly includes:

[0022] A scraper is rotatably disposed inside the reaction chamber and closely attached to the bottom wall of the reaction chamber; the inner end of the scraper penetrates through the center of the bottom wall of the reaction crucible and extends to the outside of the reaction crucible, and the outer end of the scraper is close to the inner side wall of the reaction crucible.

[0023] A rotary motor is located below the reaction crucible, and the output end of the rotary motor is connected to the end of the scraper that extends outside the reaction crucible.

[0024] In some embodiments of the present invention, the horizontal cross-section of the bottom of the reaction crucible is square, the discharge port is arranged along a direction parallel to any one of the side walls of the reaction crucible, and the discharge assembly includes:

[0025] A pusher plate is movably disposed within the reaction chamber and is in close contact with the bottom wall and the inner side wall connected to the bottom wall of the reaction chamber; the pusher plate is arranged parallel to the discharge port;

[0026] The second screw is rotatably mounted inside the reaction crucible and is arranged perpendicular to the pusher plate;

[0027] The second motor is located outside the reaction crucible and is connected to the second screw;

[0028] The push plate is mounted on the second screw and can reciprocate along the axial direction of the second screw as the second screw rotates.

[0029] In some embodiments of the present invention, the reaction crucible is provided with a partition that divides the reaction chamber into an upper chamber and a lower chamber; the reaction assembly is disposed in the upper chamber and the discharge assembly is disposed in the lower chamber; the partition has a first working state and a second working state. In the first working state, the partition is horizontally arranged in the reaction chamber to isolate the upper chamber and the lower chamber; in the second working state, the partition is inclinedly arranged in the reaction chamber to connect the upper chamber and the lower chamber.

[0030] In some embodiments of the present invention, a tantalum carbide layer is provided on the inner wall of the reaction crucible.

[0031] According to an embodiment of the present invention, a method for synthesizing silicon carbide powder using the above-described synthesis apparatus includes:

[0032] In the first stage, the vacuum device is connected to the vent at the top of the reaction crucible, and the vacuum device is activated to evacuate the crucible to a vacuum level of 6 × 10⁻⁶. -6 mbar;

[0033] In the second stage, reactive gas is introduced into the reaction crucible through the first inlet, with the total inlet flow rate controlled at 300-400 sccm. The reactive gas is a uniformly mixed carbon source gas and silicon source gas, with a molar ratio of carbon atoms in the carbon source gas to silicon atoms in the silicon source gas of 1:1. Argon gas is introduced into the reaction crucible through the second inlet, with the argon flow rate controlled at 70-150 sccm. Simultaneously, the vacuum device is controlled to maintain the internal pressure of the reaction crucible at 100-120 mbar for 30-60 minutes.

[0034] In the third stage, heating begins until the inside of the reaction crucible gradually reaches a stable temperature field; at the same time, the flow rate of the reaction gas is increased to 500-600 sccm, and the reaction gases begin to react to synthesize silicon carbide powder.

[0035] In the fourth stage, during the synthesis of silicon carbide powder, the synthesized silicon carbide powder is periodically conveyed to the bottom of the reaction crucible, and the discharge component is controlled to push the silicon carbide powder accumulated at the bottom of the reaction crucible to the discharge port and discharged through the discharge port.

[0036] In some embodiments of the present invention, the heating stage in the third stage includes a pre-stage and a post-stage. In the pre-stage, heating begins, raising the temperature to 800-900°C within 1 hour. In the post-stage, heating continues, gradually stabilizing the temperature at 1000-1100°C within 3 hours.

[0037] According to the synthesis method for preparing silicon carbide powder using a synthesis apparatus in the embodiments of the present invention, silicon carbide powder is prepared by using a gas containing carbon atoms and silicon atoms as a reaction source. This method is less likely to introduce solid particulate impurities and can greatly improve the purity of the final silicon carbide powder. At the same time, the reaction and discharge can be carried out simultaneously, realizing uninterrupted production and improving yield and efficiency.

[0038] 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

[0039] Figure 1 This is a schematic diagram of an apparatus for synthesizing silicon carbide powder according to an embodiment of the present invention;

[0040] Figure 2 yes Figure 1 Top view of the crucible lid;

[0041] Figure 3 yes Figure 1 A schematic diagram of the bottom of the crucible body;

[0042] Figure 4 yes Figure 1A diagram illustrating the usage status of the data;

[0043] Figure 5 yes Figure 1 A schematic diagram showing the collector being moved to the bottom of the reaction rod;

[0044] Figure 6 This is a schematic diagram of an apparatus for synthesizing silicon carbide powder according to another embodiment of the present invention;

[0045] Figure 7 yes Figure 6 Top view of the crucible lid;

[0046] Figure 8 yes Figure 6 Cross-sectional view of the bottom push plate of the intermediate reaction crucible;

[0047] Figure 9 yes Figure 6 A top view of the bottom of the reaction crucible.

[0048] Figure label:

[0049] Silicon carbide powder synthesis apparatus 100;

[0050] Reaction crucible 10; reaction chamber 101; crucible body 11; crucible lid 12; first air inlet 13; second air inlet 14; material outlet 15; air outlet 16;

[0051] Reaction assembly 20; reaction rod 21; collector 22; drive mechanism 23; first screw 231; first motor 232; connecting plate 233;

[0052] Discharge assembly 30; scraper 31; rotary motor 32; pusher plate 33; second screw 34; second motor 35;

[0053] partition 40;

[0054] 50 motor;

[0055] Vacuum device 60;

[0056] Gas flow controller 70;

[0057] 80mm discharge hopper;

[0058] Infrared thermometer 90;

[0059] 200g of silicon carbide powder;

[0060] Quartz dome 300;

[0061] Induction coil 400. Detailed Implementation

[0062] 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.

[0063] 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.

[0064] The following is for reference. Figures 1-9 An apparatus 100 for synthesizing silicon carbide powder according to an embodiment of the present invention includes: a reaction crucible 10, a reaction assembly 20, and a discharge assembly 30.

[0065] Reference Figures 1 to 9 As shown, the reaction crucible 10 defines a reaction chamber 101. The upper part of the side wall of the reaction crucible 10 has a first inlet 13 for introducing reaction gas, and the lower part of the side wall has a second inlet 14 for introducing carrier gas. The top of the reaction crucible 10 has an outlet 16, and the bottom of the reaction crucible 10 has a discharge port 15. Multiple reaction components 20 are disposed within the reaction chamber 101, providing a reaction site and conveying the generated silicon carbide powder to the bottom of the reaction chamber 101. A discharge component 30 is disposed within the reaction chamber 101, pushing the silicon carbide powder 200 accumulated at the bottom of the reaction chamber 101 to the discharge port 15. A discharge hopper 80 is provided at the discharge port 15 at the bottom of the reaction crucible 10. The discharge hopper 80 has a valve, and by controlling the valve, the silicon carbide powder 200 entering the discharge hopper 80 from the discharge port 15 is discharged to the outside of the reaction crucible 10. The reaction gas introduced into the reaction chamber 101 through the first inlet 13 may include a carbon source gas and a silicon source gas in a certain molar ratio. The specific molar ratio is determined by the content of carbon atoms in the carbon source gas and silicon atoms in the silicon source gas. For example, the reaction gas may be methane-silicon and acetylene in a molar ratio of 2:1, or methane-silicon and ethylene in a molar ratio of 2:1, as long as the molar ratio of carbon atoms in the carbon source gas to silicon atoms in the silicon source gas is 1:1. Correspondingly, the carrier gas introduced into the reaction chamber 101 through the second inlet 14 may be argon or krypton, etc.

[0066] Specifically, refer to Figures 1 to 9As shown, the reaction crucible 10 may include a crucible body 11 and a crucible lid 12. The crucible body 11 is a hollow structure with an open top, and the crucible lid 12 is located on top of the crucible body 11. The crucible body 11 and the crucible lid 12 together define the reaction chamber 101 to provide reaction space. At the same time, the reaction crucible 10 (i.e., the crucible body 11 and the crucible lid 12) may be made of graphite, thereby giving it high-temperature resistance. Similar to the growth crucible for preparing silicon carbide crystals using the PVT method, the entire reaction crucible 10 is placed inside a quartz cover 300. The outside of the reaction crucible 10 may be provided with a heat insulation layer, and an induction coil 400 is provided around the outer ring of the heat insulation layer. The induction coil 400 is used to provide a thermal field to facilitate the provision of the temperature conditions required for silicon carbide powder synthesis. For example, the induction coil 400 may be arranged outside the reaction crucible 10 directly opposite the reaction assembly 20. The first gas inlet 13 is located on the upper part of the side wall of the crucible body 11 to introduce reaction gas into the reaction chamber 101. There can be multiple first gas inlets 13, which can be arranged in multiple layers, with multiple inlets per layer. Multiple first gas inlets 13 in the same layer are evenly distributed along the circumferential direction of the crucible body 11 on the side wall. Correspondingly, the second gas inlet 14 is located on the lower part of the side wall of the crucible body 11, that is, below the first gas inlet 13, to introduce carrier gas into the reaction chamber 101. There can also be multiple second gas inlets 14, which are also evenly distributed along the circumferential direction of the crucible body 11 on the side wall. Multiple reaction components 20 can be evenly distributed within the reaction chamber 101 to ensure uniformity throughout the reaction chamber 101 while the reaction proceeds. The reaction assembly 20 can be installed on the crucible cover 12, located at the top of the entire reaction chamber 101. When the reaction gas starts to react, the generated silicon carbide powder will be deposited on the reaction assembly 20 and can be detached from the reaction assembly 20 and transported to the bottom of the reaction chamber 101. Then, the discharge assembly 30 at the bottom pushes the silicon carbide powder accumulated at the bottom to the discharge port 15 to achieve continuous operation of growing and discharging at the same time.

[0067] Understandably, a vacuum device 60 is first connected to the outlet 16 to evacuate the reaction crucible 10, thereby removing air impurities from the reaction chamber 101 and preventing the introduction of impurities that could reduce purity. Next, a uniformly mixed carbon source gas and silicon source gas are introduced into the reaction crucible 10 through the first inlet 13, wherein the molar ratio of carbon atoms in the carbon source gas to silicon atoms in the silicon source gas is 1:1; simultaneously, argon gas is introduced as the carrier gas through the second inlet 14. It is important to note that the vacuum device 60 remains operational while the reaction gas and carrier gas are being introduced to maintain stable pressure inside the reaction chamber 101. Then, under the action of the external induction coil 400, the temperature of the reaction crucible 10 gradually increases and transfers heat to the reaction gas inside it. When the temperature rises to 1000-1100℃, crystal growth begins, that is, the reaction gas begins to react, gradually generating silicon carbide powder, which is deposited on the reaction component 20 and then falls off from the reaction component 20 to the bottom of the reaction chamber 101. When the silicon carbide powder at the bottom accumulates to a certain amount, it is discharged outward through the discharge port 15 by the discharge component 30. When the bottom silicon carbide powder has not reached the preset discharge value, the valve on the discharge hopper 80 at the discharge port 15 remains closed. The valve opens only when discharge is required, and during the valve opening process, argon gas is continuously introduced through the second air inlet 14. Since argon gas is heavy, the introduced argon gas will always be at the lower part of the reaction chamber 101, which can prevent the reaction gas in the reaction chamber 101 from moving downwards. This ensures that the reaction gas is always at the upper part of the reaction chamber 101, ensuring the continued progress of the reaction and guaranteeing that the synthesized powder can be transferred out of the reaction crucible 10 without interrupting the reaction. At the same time, the introduction of argon gas can also cool down the silicon carbide powder that falls off from the reaction component 20.

[0068] It should be noted that the reaction component 20 can also be made of graphite. On the one hand, it can serve as a reaction site. More reaction components 20 can provide a larger specific surface area and more reaction sites, thereby increasing the yield. On the other hand, it can serve as a heat source. Due to the use of induction heating, the graphite reaction component 20 itself can also generate heat, which can reach the reaction temperature more quickly. At the same time, the reaction components 20 are evenly arranged, which can achieve uniform heating and uniform reaction.

[0069] According to the silicon carbide powder synthesis apparatus of the present invention, a gas containing carbon and silicon atoms is used as the reaction source. The reaction gas is introduced into the reaction crucible 10, and silicon carbide powder is synthesized by chemical decomposition and synthesis deposition at high temperature. The synthesized silicon carbide powder is deposited on the reaction component 20 and transported to the bottom of the reaction chamber 101. When the silicon carbide powder at the bottom reaches a preset value, the discharge component 30 pushes the accumulated silicon carbide powder at the bottom to the outside of the reaction crucible 10 through the discharge port. The reaction and discharge can be carried out simultaneously, realizing uninterrupted production and improving efficiency. At the same time, the preparation is carried out by gas synthesis, which is less likely to introduce solid particulate impurities and can greatly improve the purity of the final silicon carbide powder. This method can control the purity of silicon carbide powder between 99.999% and 99.9999%.

[0070] In some embodiments of the present invention, reference is made to... Figures 1 to 9 As shown, the reaction assembly 20 includes a reaction rod 21, a collector 22, and a drive mechanism 23. The reaction rod 21 is arranged inside the reaction chamber 101 to provide a reaction site. The collector 22 is disposed on the reaction rod 21 and can reciprocate along the axial direction of the reaction rod 21 to peel off the silicon carbide powder deposited on the reaction rod 21. The drive mechanism 23 is connected to the collector 22 to drive the collector 22 to move along the reaction rod 21. Both the reaction rod 21 and the collector 22 can be made of graphite to provide high-temperature resistance. The reaction rod 21 can be a square or round rod, vertically arranged inside the reaction chamber 101, with its top end connected to the crucible cover 12. There can be one or more reaction rods 21. Correspondingly, there can also be one or more collectors 22. Each collector 22 has a mounting hole that mates with the reaction rod 21. The collector 22 is fitted onto the reaction rod 21 through the mounting hole and reciprocates along the reaction rod 21 under the drive of the drive mechanism 23. For example, if there is one reaction rod 21, then there is also one collector 22. If there are two reaction rods 21, then there can be one or two collectors 22. If there is one collector 22, then the collector 22 has two mounting holes and can be fitted onto two reaction rods 21 simultaneously. If there are two collectors 22, then the two collectors 22 are fitted onto the two reaction rods 21 one-to-one, and the drive mechanism 23 is connected to all collectors 22 to drive their movement. Similarly, if there are three or more reaction rods 21, then there can be one or more collectors 22, and their specific connection relationship is the same as the principle described above, which will not be repeated here.

[0071] Understandably, initially, the collector 22 can be positioned at the top of the reaction rod 21. When synthesis begins, the reactant gas generates silicon carbide powder on the surface of the reaction rod 21. By controlling the drive mechanism 23, the collector 22 can be moved downwards from the top of the reaction rod 21. The collector 22 exerts a downward force on the silicon carbide powder deposited on the reaction rod 21, peeling the powder off and allowing it to fall to the bottom of the reaction chamber 101 under gravity. Once the collector 22 reaches the bottom of the reaction rod 21, the drive mechanism 23 is then used to move the collector 22 upwards from the bottom of the reaction rod 21 until it returns to its initial state, i.e., reaches the top of the reaction rod 21. During this upward movement, the silicon carbide powder deposited on the reaction rod 21 can also be peeled off. Once the collector 22 reaches the top of the reaction rod 21, the drive mechanism 23 can be controlled to move the collector 22 downwards… Repeating this action removes the silicon carbide powder deposited on the reaction rod 21. In other words, the cooperation of the reaction rod 21, collector 22, and drive mechanism 23 enables automatic growth and peeling of silicon carbide powder, and also achieves continuous operation of growth and peeling simultaneously. Considering the need for crystal particle growth time, the moving speed of the collector 22 should not be too fast; and by controlling the reaction time, the particle size can be controlled. Therefore, the length of the reaction rod 21 can be controlled to be 50-70 cm, so that the time for each cycle of the collector 22 is 30-50 minutes. This avoids excessively long time resulting in excessive powder bonding, and insufficient powder synthesis due to too short time.

[0072] In some embodiments of the present invention, a silicon carbide layer may also be provided on the reaction rod 21. For example, the silicon carbide layer may be a silicon carbide thin film coated on the reaction rod 21. As a homogeneous crystal, the silicon carbide thin film can serve as an adsorption site for crystal seeds, providing a nucleation and attachment surface for crystal formation. Compared to a graphite-based reaction rod 21, the silicon carbide thin film more easily promotes the crystal growth of silicon carbide generated by the reaction of reactive gases on the reaction rod 21, further improving efficiency.

[0073] In some embodiments of the present invention, the driving mechanism 23 may include: a first screw 231, a first motor 232, and a connecting plate 233. The first screw 231 is disposed inside the reaction chamber and rotatably mounted on the reaction crucible 10. For example, the first screw 231 is arranged parallel to the reaction rod 21, both vertically arranged inside the reaction chamber 101. The upper end of the first screw 231 penetrates the crucible cover 12 and extends to the outside of the crucible cover 12. The first motor 232 is disposed outside the reaction crucible 10. The first motor 232 is connected to the first screw 231. Specifically, the first motor 232 is mounted on the outer wall of the crucible cover 12 via a bracket, and its output end is connected to the end of the first screw 231 extending outside the crucible cover 12 to drive the first screw 231 to rotate synchronously. The connecting plate 233 is disposed on the first screw 231 and can reciprocate along the axial direction of the first screw 231 as the first screw 231 rotates. At the same time, the connecting plate 233 is connected to the collector 22 to drive the collector 22 to move synchronously. The first motor 232 is a bidirectional servo motor, and its rotation speed and rotation direction can be set as needed to control the direction and speed of movement of the collector 22 on the reaction rod 21. In the initial state, the connecting plate 233 is located at the top of the first screw 231, and the collector 22 is located at the top of the reaction rod 21.

[0074] Understandably, if there is one collector 22 in the reaction assembly 20, and the collector 22 is fitted onto one or more reaction rods 21, then the connecting plate 233 is connected to the collector 22. When a certain amount of silicon carbide powder is deposited on the reaction rod 21 or after a certain reaction time, the first motor 232 is started. The first screw 231 will rotate under the drive of the first motor 232, and the connecting plate 233 will move downward along the first screw 231, while simultaneously driving the collector 22 to move downward. The collector 22 will exert a downward force on the particles deposited on the reaction rod 21 to peel the silicon carbide powder off the reaction rod 21, and it will fall into the bottom of the reaction chamber 101 under the action of gravity. When the connecting plate 233 moves to the bottom of the first screw 231, the first motor 232 is controlled to rotate in the opposite direction, and the first screw 231 will also rotate in the opposite direction. The connecting plate 233 will move upward along the first screw 231, simultaneously driving the collector 22 upward until the collector 22 returns to its initial state (i.e., reaches the top of the reaction rod 21). Then, the first motor 232 is controlled to rotate in the forward direction, and the first screw 231 rotates in the forward direction... The above actions are repeated to achieve continuous operation of growing and unloading simultaneously. By controlling the first motor 232, the rotation speed and direction of the first screw 232 can be controlled, thereby controlling the reaction time and, consequently, the size of the silicon carbide powder deposited on the reaction rod 21.

[0075] Therefore, if there are multiple collectors 22 and multiple reaction rods 21 in the reaction assembly 20, the multiple reaction rods 21 can be arranged around the first screw 231. The multiple collectors 22 on the reaction rods 21 are all connected to the connecting plate 233 on the first screw 231, that is, the multiple collectors 22 are arranged around the connecting plate 233 and connected to it. When the first motor 232 drives the first screw 231 to rotate, under the action of the connecting plate 233, the multiple collectors 22 can simultaneously move up and down along the corresponding reaction rods 21, realizing the automatic growth and peeling of silicon carbide powder on the reaction rods 21, and also realizing continuous operation of growth and peeling simultaneously, thus improving efficiency. The working process of the first motor 232 is the same as described above and will not be repeated here.

[0076] In some embodiments of the present invention, reference is made to... Figures 1 to 5 As shown, the horizontal cross-section of the bottom of the reaction crucible 10 is circular. For example, the reaction crucible 10 can be a cylindrical structure. In this case, the discharge port 15 can be arranged from the center to the circumference of the bottom wall of the reaction crucible 10, that is, the inner end of the discharge port 15 is close to the center of the bottom wall of the reaction crucible 10, and the outer end is to the side wall of the reaction crucible 10. For example, the discharge port 15 can be arranged along the radial direction of the bottom wall of the reaction crucible 10 (i.e., along the radial direction), or it can be arranged along the line connecting the center to any point on the circumference. In order to discharge all the silicon carbide powder accumulated at the bottom of the reaction chamber 101 to the outside of the reaction crucible 10 through the discharge port 15, the discharge assembly 30 may include: a scraper 31 and a rotary motor 32. The scraper 31 is rotatably disposed in the reaction chamber 101 and closely attached to the bottom wall of the reaction chamber 101. The inner end of the scraper 31 penetrates through the center of the bottom wall of the reaction crucible 10 and extends to the outside of the reaction crucible 10, and the outer end of the scraper 31 is close to the inner side wall of the reaction crucible 10. The rotary motor 32 is disposed below the reaction crucible 10, and the output end of the rotary motor 32 is connected to the end of the scraper 31 that extends to the outside of the reaction crucible 10.

[0077] Specifically, the scraper 31 can be an L-shaped folding plate. One side of the L-shaped folding plate is rotatably mounted at the center of the bottom wall of the reaction crucible 10 and extends to the outside of the reaction crucible 10. The output end of the rotary motor 32 is connected to the end of the L-shaped folding plate that extends below the reaction crucible 10. The length of the other side of the L-shaped folding plate is equal to the radius of the circle. When the rotary motor 32 is working, it can drive the L-shaped folding plate to rotate around the center, so as to give a pushing force to the silicon carbide powder accumulated at the bottom, continuously pushing it into the discharge port 15, and then sending it to the outside of the reaction crucible 10. Since the discharge port 15 is arranged from the center to the circumference, as the L-shaped folding plate rotates, all the silicon carbide powder accumulated at the bottom can be pushed into the discharge port 15.

[0078] Understandably, when silicon carbide powder accumulates to a certain amount at the bottom of the reaction crucible 10, the rotary motor 32 can be activated. Driven by the rotary motor 32, the L-shaped baffle rotates around its center, pushing the silicon carbide powder at the bottom towards the discharge port 15, completing one discharge cycle. When the rotary motor 32 stops, the L-shaped baffle stops rotating, and the silicon carbide powder stops moving towards the discharge port 15. To further control the discharge, a weighing device can be installed at the bottom of the reaction crucible 10, and used in conjunction with this device to determine whether to begin external conveying. For example, a weight sensor can be installed inside the bottom wall of the reaction crucible 10. The weight sensor detects the weight of the silicon carbide powder at the bottom in real time. When the detected value reaches a preset value, a signal is sent to the rotary motor 32 to activate it. The L-shaped baffle then pushes the silicon carbide powder at the bottom, achieving automatic discharge.

[0079] Of course, the scraper 31 can also be of other structures, such as a straight plate. Meanwhile, a power shaft is provided at the center of the bottom wall of the reaction crucible 10, penetrating the bottom wall of the reaction crucible 10. The length of the straight plate is equal to the radius of the circle. The top end of the power shaft is connected to the inner end of the straight plate, and the outer end of the straight plate is connected to the side wall of the reaction crucible 10. The lower end of the power shaft is connected to the output end of the rotary motor 32. When the rotary motor 32 is working, the straight plate will rotate around the power shaft under the action of the power shaft, thereby pushing the silicon carbide powder at the bottom and continuously scraping the silicon carbide powder into the discharge port 15 to complete the discharge.

[0080] In some embodiments of the present invention, reference is made to... Figures 6 to 9 As shown, the horizontal cross-section of the bottom of the reaction crucible 10 is square. For example, the reaction crucible 10 can be a cuboid structure. In this case, the discharge port 15 is arranged parallel to any one of the side walls of the reaction crucible 10, that is, the two ends of the discharge port 15 reach two opposite side walls of the reaction crucible 10. Correspondingly, the discharge assembly 30 may include: a pusher plate 33, a second screw 34, and a second motor 35. The pusher plate 33 is movably disposed in the reaction chamber 101 and is in close contact with the bottom wall of the reaction chamber 101 and the inner side wall connected to the bottom wall. The pusher plate 33 is arranged parallel to the discharge port 15. The second screw 34 is rotatably installed in the reaction crucible 10 and is arranged perpendicular to the pusher plate 33. The second motor 35 is disposed outside the reaction crucible 10 and is connected to the second screw 34. The pusher plate 33 is mounted on the second screw 34 and can reciprocate along the axial direction of the second screw 34 as the second screw 34 rotates. For example, there is one discharge port 15, which is arranged close to the side wall of the reaction crucible 10. In the initial state, the pusher plate 33 is located on the end of the second screw 34 away from the discharge port 15. The second motor 35 is a bidirectional servo motor to drive the second screw 34 to rotate in either the forward or reverse direction.

[0081] Understandably, when silicon carbide powder accumulates to a certain amount at the bottom of the reaction crucible 10, the second motor 35 can be activated. The second motor 35 will drive the second screw 34 to rotate, and the pusher plate 33 will move along the second screw 34 towards the discharge port 15 to push the silicon carbide powder towards the discharge port 15, completing the discharge. Then, the second screw 34 is controlled to rotate in the opposite direction so that the pusher plate 33 returns to its initial state.

[0082] Considering that the reaction is still in progress during the movement of the pusher plate 33, some silicon carbide powder will fall onto the side of the pusher plate 33 away from the discharge port 15. As the pusher plate 33 moves towards its initial state (away from the discharge port), this portion of silicon carbide powder will accumulate at the bottom and will not be pushed to the discharge port 15. To solve this problem, in some embodiments of the present invention, the reaction crucible 10 is provided with a partition 40 that divides the reaction chamber 101 into an upper chamber and a lower chamber; the reaction assembly 20 is disposed in the upper chamber, and the discharge assembly 30 is disposed in the lower chamber; the partition 40 has a first working state and a second working state. In the first working state, the partition 40 is horizontally arranged in the reaction chamber 101 to separate the upper chamber and the lower chamber; in the second working state, the partition 40 is inclinedly arranged in the reaction chamber 101 to connect the upper chamber and the lower chamber. For example, the two ends of the partition 40 are rotatably mounted on the side wall of the reaction crucible 10, and one end extends to the outside of the reaction crucible 10; the outside of the reaction crucible 10 is provided with a power motor 50 connected to the extended end of the partition 40 to drive the partition 40 to rotate, thereby realizing free switching between the first working state and the second working state.

[0083] Under normal circumstances, the partition 40 is in the second working state, with the upper and lower chambers connected. The generated silicon carbide powder can pass through the upper chamber to the lower chamber and fall to the bottom of the reaction chamber 101. When the silicon carbide powder at the bottom accumulates to a certain amount, the second motor 35 starts working, the second screw 34 starts rotating, and the pusher plate 33 moves from its initial state towards the discharge port 15. At the same time, the power motor 50 starts working, driving the partition 40 to switch from the second working state to the first working state. During the movement of the pusher plate 33, the partition 40 remains in the first working state, and the silicon carbide powder generated during this period will fall onto the partition 40. When the pusher plate 33 returns to its initial state, the power motor 50 starts to work, the partition plate 40 rotates, and switches from the first working state to the second working state. The silicon carbide powder on the partition plate 40 will fall back to the bottom of the reaction chamber 101 and be located between the pusher plate 33 and the discharge port 15. This ensures that the silicon carbide powder will not fall onto the side of the pusher plate 33 away from the discharge port 15, thereby avoiding unclean discharge.

[0084] Of course, in addition to adding a partition 40, the number of discharge ports 15 can be increased, and the position of the pusher plate 33 can be adjusted to ensure that the silicon carbide powder at the bottom can be completely discharged. For example, there can be two discharge ports 15, located at both ends of the bottom of the reaction crucible 10, and the pusher plate 33 can be set between the two discharge ports 15. Under the action of the second motor 35 and the second screw 34, the pusher plate 22 can move back and forth between the two discharge ports 15 to completely discharge the silicon carbide powder and avoid the situation of incomplete discharge.

[0085] Considering that some silicon carbide powder will deposit on the inner wall of the reaction crucible 10 during the reaction process, and that the deposited silicon carbide powder cannot be discharged and may affect the operation of the internal reaction components 20 over time, in order to reduce its deposition on the inner wall of the reaction crucible 10, in some embodiments of the present invention, as shown with reference to the figure, a tantalum carbide layer can be provided on the inner wall of the reaction crucible 10. The provision of the tantalum carbide layer can prevent the silicon carbide powder generated in the reaction from depositing on the inner wall of the reaction crucible 10, further improve the removal rate of silicon carbide powder, and ensure that other internal components are not affected and can operate normally.

[0086] According to an embodiment of the present invention, a method for preparing silicon carbide powder using a synthesis apparatus includes: a first stage, connecting a vacuum device 60 to the vent hole at the top of the reaction crucible, and activating the vacuum device to evacuate the air, so that the vacuum degree inside the reaction crucible is 6 × 10⁻⁶. -6 In the second stage, reactant gas is introduced into the reaction crucible through the first inlet, with the total inlet flow rate controlled at 300-400 sccm. The reactant gas is a homogeneous mixture of carbon source gas and silicon source gas, with a molar ratio of carbon atoms in the carbon source gas to silicon atoms in the silicon source gas of 1:1. Argon gas is introduced into the reaction crucible through the second inlet, with the argon flow rate controlled at 70-150 sccm. Simultaneously, the vacuum device is controlled to maintain the internal pressure of the reaction crucible at 100- In the third stage, heating begins at 120 mbar and is maintained for 30-60 minutes until a stable temperature field is gradually reached inside the reaction crucible. Simultaneously, the flow rate of the reaction gas is increased to 500-600 sccm, and the reaction gases begin to react, synthesizing silicon carbide powder. In the fourth stage, during the synthesis of silicon carbide powder, the synthesized silicon carbide powder is periodically conveyed to the bottom of the reaction crucible, and the discharge component is controlled to push the silicon carbide powder accumulated at the bottom of the reaction crucible to the discharge port, and discharged through the discharge port.

[0087] For example, refer to Figures 1 to 9As shown, in one example, in the first stage, the vacuum device 60 can be connected to the outlet 16. Inlet pipes are connected to both the first inlet 13 and the second inlet 14. Valves and gas flow controllers 70 are installed on the inlet pipes. All valves on the inlet pipes and the discharge hopper 80 are closed. The vacuum device 60 is then activated to evacuate the reaction chamber 101, achieving a vacuum level of 6 × 10⁻⁶. -6 mbar can extract air impurities from the reaction crucible 10, preventing impurities from being introduced into subsequent reactions and causing a decrease in purity.

[0088] In the second stage, on one hand, the valve on the inlet pipe connected to the first inlet 13 is opened to introduce reactive gas into the upper part of the reaction chamber 101. The reactive gas is a homogeneous mixture of methane, silicon, and acetylene with a molar ratio of 2:1. The total inlet flow rate of the reactive gas is controlled at 300-400 sccm by the gas flow controller 70. On the other hand, the valve on the inlet pipe connected to the second inlet 14 is opened to introduce argon gas into the bottom of the reaction chamber 101. The argon gas flow rate is controlled at 70-150 sccm. Simultaneously, the top vacuum device 80 is activated to maintain the internal pressure of the reaction chamber 101 at 100-120 mbar. This stage serves as the pre-reaction gas filling stage and requires continuous gas filling and pressure stabilization for 30-60 minutes. Through the control of the first and second stages, the removal of air impurities inside the reaction chamber 101 can be ensured. At the same time, since argon gas and reactive gas have different molar masses, the suction from top to bottom by the vacuum device 80 can keep the gas in the reaction chamber 101 in a stratified state. The overall structure consists of reactant gas at the top and argon gas at the bottom, thus forming a stable first and second phase state.

[0089] In the third stage, heating begins, and the temperature is monitored and controlled via an infrared thermometer 90 inside the quartz dome 300. The entire heating and temperature control process is divided into two stages: a pre-stage and a post-stage. In the pre-stage, the power is controlled to raise the temperature to 800-900℃ within 1 hour; in the post-stage, heating continues, gradually stabilizing the temperature at 1000-1100℃ within 3 hours. This power control method ensures a stable temperature field inside the reaction crucible 10 within a short time. Simultaneously, the reaction gas flow rate is increased to 500-600 sccm to ensure the first phase is in a supersaturated state. At this stage, the reaction begins, and the third phase, silicon carbide powder, begins to synthesize. The entire third stage is expected to last 4 hours, with a stable voltage of 100-120 mbar.

[0090] In the fourth stage, during the synthesis of silicon carbide powder, the silicon carbide powder deposited on the reaction component 20 is periodically peeled off from the reaction component 20. The peeled silicon carbide powder 200 falls to the bottom of the reaction chamber 101 under the action of gravity. The discharge component 30 is controlled to push the silicon carbide powder 200 accumulated at the bottom of the reaction crucible 10 to the discharge port 15, and then discharges it to the outside of the reaction crucible 10 through the discharge port 15. The principle of silicon carbide powder 200 conveying and the coordination of various components during discharge can be found in the above description, and will not be repeated here.

[0091] According to the method for preparing silicon carbide powder using a synthesis apparatus according to an embodiment of the present invention, the inside of the reaction crucible 10 is first evacuated to remove air impurities and avoid the introduction of impurities that would reduce purity. Then, a certain proportion of carbon source gas and silicon source gas are introduced into the reaction crucible 10, and a carrier gas is introduced into the reaction crucible 10 at the same time. With the cooperation of the vacuum device 80, the reaction chamber 101 can be layered with the reaction gas on top and the carrier gas below, which is conducive to the reaction of the reaction gas. Next, silicon carbide powder is synthesized by chemical decomposition and synthesis deposition at high temperature. The synthesized silicon carbide powder is deposited on the reaction component 20 and transported to the bottom of the reaction chamber 101. When the silicon carbide powder at the bottom reaches a preset value, the discharge component 30 pushes the silicon carbide powder accumulated at the bottom to the outside of the reaction crucible 10 through the discharge port. The reaction and discharge can be carried out simultaneously to achieve uninterrupted production and improve efficiency. Meanwhile, the gas synthesis method minimizes the introduction of solid particulate impurities, significantly improving the purity of the final silicon carbide powder. Testing of the synthesized silicon carbide powder revealed a purity between 99.999% and 99.9999%. Furthermore, during the synthesis process, gaseous byproducts such as H2, being relatively light, accumulate at the top of the reaction chamber 101. Simultaneously, with the continuous introduction of reaction gases and the continuous suction of the vacuum device, these gases can be expelled from the reaction crucible 10, maintaining stability within the reaction chamber 101.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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 silicon carbide powder, characterized in that, include: A reaction crucible, which defines a reaction chamber, has a discharge port at the bottom and a discharge hopper at the discharge port at the bottom of the reaction crucible; The reaction assembly comprises multiple reaction assemblies disposed within the reaction chamber, which serve to provide a reaction site and transport the silicon carbide powder generated by the reaction to the bottom of the reaction chamber; A discharge assembly is disposed inside the reaction chamber and is used to push the silicon carbide powder accumulated at the bottom of the reaction chamber to the discharge port; The reaction crucible has a first inlet for the reaction gas to enter on the upper part of its sidewall, and a second inlet for the carrier gas to enter on the lower part of its sidewall; the top of the reaction crucible has an outlet. The reaction assembly includes a reaction rod, a collector, and a drive mechanism. The reaction rod is arranged inside the reaction chamber to provide a reaction site. A silicon carbide layer is provided on the reaction rod. The collector is disposed on the reaction rod and can reciprocate along the axial direction of the reaction rod to peel off the silicon carbide powder deposited on the reaction rod. The drive mechanism is connected to the collector to drive the movement of the collector on the reaction rod. The driving mechanism includes a first screw, a first motor, and a connecting plate. The first screw is disposed inside the reaction chamber and rotatably mounted on the reaction crucible. The first motor is disposed outside the reaction crucible and connected to the first screw. The connecting plate is disposed on the first screw and can reciprocate along the axial direction of the first screw as it rotates. The first screw is arranged parallel to the reaction rod. The connecting plate is connected to the collector.

2. The apparatus for synthesizing silicon carbide powder according to claim 1, characterized in that, The reaction crucible has a circular horizontal cross-section, and the discharge port is arranged from the center to the circumference of the bottom wall of the reaction crucible. The discharge assembly includes: A scraper is rotatably disposed inside the reaction chamber and closely attached to the bottom wall of the reaction chamber; the inner end of the scraper penetrates through the center of the bottom wall of the reaction crucible and extends to the outside of the reaction crucible, and the outer end of the scraper is close to the inner side wall of the reaction crucible. A rotary motor is located below the reaction crucible, and the output end of the rotary motor is connected to the end of the scraper that extends outside the reaction crucible.

3. The apparatus for synthesizing silicon carbide powder according to claim 1, characterized in that, The reaction crucible has a square horizontal cross-section, and the discharge port is arranged parallel to any one of the side walls of the reaction crucible. The discharge assembly includes: A pusher plate is movably disposed within the reaction chamber and is in close contact with the bottom wall and the inner side wall connected to the bottom wall of the reaction chamber; the pusher plate is arranged parallel to the discharge port; The second screw is rotatably mounted inside the reaction crucible and is arranged perpendicular to the pusher plate; The second motor is located outside the reaction crucible and is connected to the second screw; The push plate is mounted on the second screw and can reciprocate along the axial direction of the second screw as the second screw rotates.

4. The apparatus for synthesizing silicon carbide powder according to claim 3, characterized in that, The reaction crucible is provided with a partition that divides the reaction chamber into an upper chamber and a lower chamber; the reaction assembly is located in the upper chamber and the discharge assembly is located in the lower chamber; the partition has a first working state and a second working state. In the first working state, the partition is horizontally arranged in the reaction chamber to separate the upper chamber and the lower chamber. In the second working state, the partition is arranged at an angle inside the reaction chamber so that the upper chamber and the lower chamber are connected.

5. An apparatus for synthesizing silicon carbide powder according to any one of claims 1 to 4, characterized in that, The inner wall of the reaction crucible is provided with a tantalum carbide layer.

6. A method for synthesizing silicon carbide powder using the synthesis apparatus according to claim 1, characterized in that, include: In the first stage, the vacuum device is connected to the vent at the top of the reaction crucible, and the vacuum device is activated to draw a vacuum, so that the vacuum level inside the reaction crucible is [missing information]. ; In the second stage, reactive gas is introduced into the reaction crucible through the first inlet, with the total inlet flow rate controlled at 300-400 sccm. The reactive gas is a uniformly mixed carbon source gas and silicon source gas, with a molar ratio of carbon atoms in the carbon source gas to silicon atoms in the silicon source gas of 1:

1. Argon gas is introduced into the reaction crucible through the second inlet, with the argon flow rate controlled at 70-150 sccm. Simultaneously, the vacuum device is controlled to maintain the internal pressure of the reaction crucible at 100-120 mbar for 30-60 minutes. In the third stage, heating begins until the inside of the reaction crucible gradually reaches a stable temperature field; at the same time, the flow rate of the reaction gas is increased to 500-600 sccm, and the reaction gases begin to react to synthesize silicon carbide powder. In the fourth stage, during the synthesis of silicon carbide powder, the synthesized silicon carbide powder is periodically transported to the bottom of the reaction crucible, and the discharge component is controlled to push the silicon carbide powder accumulated at the bottom of the reaction crucible to the discharge port and discharged through the discharge port.

7. The method for synthesizing silicon carbide powder according to claim 6, characterized in that, The heating stage in the third stage includes a pre-stage and a post-stage. In the pre-stage, heating begins, raising the temperature to 800-900℃ within 1 hour. In the post-stage, heating continues, gradually stabilizing the temperature at 1000-1100℃ within 3 hours.

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