CN118289763A

CN118289763A - Silicon carbide powder synthesizing equipment and synthesizing method

Info

Publication number: CN118289763A
Application number: CN202410383432.9A
Authority: CN
Inventors: 苗双柱
Original assignee: China University of Mining and Technology CUMT
Current assignee: China University of Mining and Technology CUMT
Priority date: 2024-04-01
Filing date: 2024-04-01
Publication date: 2024-07-05

Abstract

The invention discloses silicon carbide powder synthesizing equipment and a synthesizing method, comprising a furnace body, a furnace cover, a seed crystal box, a transmission device, a cooling device, a heating device and a furnace body control system, wherein a growth chamber is formed in the furnace body, a crucible is arranged in the growth chamber, temperature measuring holes are coaxially formed in the side wall of the furnace body and the side wall of the crucible, and the temperature measuring holes in the side wall of the crucible are sealed by quartz glass; the furnace cover is assembled on the upper part of the furnace body and is used for sealing the furnace body; the seed crystal box is assembled at the upper part of the crucible, and a discharging mechanism is arranged at the bottom of the seed crystal box; the conveying device is connected with the growth chamber and is used for conveying carbon powder into the crucible; the cooling device is used for cooling the furnace body; the heating device comprises an induction coil, and the induction coil is used for heating the crucible; the furnace body control system is used for controlling the transmission device, the cooling device and the heating device to work or stop working. The invention can control the grain size of the silicon carbide powder and improve the stacking density of the silicon carbide powder, so that thicker silicon carbide crystals can be grown by using the silicon carbide powder.

Description

Silicon carbide powder synthesizing equipment and synthesizing method

Technical Field

The invention relates to the technical field of semiconductors, in particular to silicon carbide powder synthesis equipment and a silicon carbide powder synthesis method.

Background

In the related art, silicon carbide is an ideal material for manufacturing high-power, high-temperature, high-frequency and radiation-proof devices as a representative of wide-gap semiconductor materials in the technical field of semiconductor materials, but since high-quality silicon carbide single crystals are difficult to obtain and the application of the material is limited, the improvement of the quality of the silicon carbide crystals is a very important research topic, wherein the preparation process has strict requirements on the particle size, the purity and the tap density distribution of powder, and the adoption of proper silicon carbide powder is one of key factors for improving the quality and the growth yield of the silicon carbide single crystals. The existing silicon carbide powder is generally obtained by adopting a solid phase synthesis mode, and because of inherent plasticity of the solid phase synthesis method, the produced silicon carbide powder is long, is in a needle shape or a flake shape, and has small bulk density, the silicon carbide powder synthesized by the mode needs to be broken and screened, the particle size cannot be ensured, the tap density is only between 1.1 and 1.4g/cm ³, and the corresponding powder porosity is about 60 percent, so that the bulk density of the silicon carbide powder is lower when the silicon carbide crystal is prepared, and the silicon carbide crystal with the thickness cannot grow.

Disclosure of Invention

In order to solve the problems, the invention provides silicon carbide powder synthesis equipment and a synthesis method, which can control the grain size of silicon carbide powder and improve the bulk density of the silicon carbide powder, so that thicker silicon carbide crystals can be grown by using the silicon carbide powder.

The invention provides silicon carbide powder synthesizing equipment which comprises a furnace body, a furnace cover, a seed crystal box, a transmission device, a cooling device, a heating device and a furnace body control system, wherein a growth chamber is formed in the furnace body, a crucible is arranged in the growth chamber, temperature measuring holes are coaxially formed in the side wall of the furnace body and the side wall of the crucible, and the temperature measuring holes in the side wall of the crucible are sealed by quartz glass; the furnace cover is assembled on the upper part of the furnace body and is used for sealing the furnace body; the seed crystal box is assembled at the upper part of the crucible, and a discharging mechanism is arranged at the bottom of the seed crystal box; the conveying device is connected with the growth chamber and is used for conveying carbon powder into the crucible; the cooling device is used for cooling the furnace body; the heating device is an induction coil, and the induction coil is used for heating the crucible; the furnace body control system is used for controlling the transmission device, the cooling device and the heating device to work or stop working.

Preferably, the side walls of the furnace body and the furnace cover are hollow structures, and the cooling device is respectively connected to the hollow structures of the furnace body and the furnace cover through cooling circulation pipelines.

Preferably, the temperature measuring Kong Kaishe is arranged at the upper part and the lower part of the crucible and the side wall of the furnace body, the temperature measuring holes on the side wall of the furnace body are correspondingly provided with infrared thermometers for detecting the temperature in the crucible in real time, and the infrared thermometers are electrically connected with the furnace body control system.

Preferably, the discharging mechanism comprises first discharging holes, a discharging plate and a rotating part, wherein the first discharging holes are uniformly distributed at the bottom of the seed crystal box; the discharging plate is arranged at the bottom of the inner side of the seed crystal box, is a hollowed-out plate, and is uniformly provided with baffle plates;

The rotary part is connected with the furnace body control system and the discharging plate respectively, the furnace body control system drives the discharging plate to rotate through the rotary part, and the discharging plate has two states:

In the first state, the rotating part drives the discharging plate to rotate, so that the first discharging hole and the baffle are staggered, and at the moment, the discharging plate is in an open state;

and in the second state, the rotating part drives the discharging plate to rotate, so that the first discharging hole is coincided with the baffle, and at the moment, the discharging plate is in a closed state.

Preferably, the rotating component comprises a stepping motor, a first rotating shaft and a second rotating shaft, wherein the stepping motor is arranged outside the furnace body, the stepping motor is connected with the furnace body control system, one end of the first rotating shaft is connected with an output shaft of the stepping motor, the other end of the first rotating shaft stretches into the growth chamber, one end of the second rotating shaft is arranged at the center of the discharging plate, the other end of the second rotating shaft stretches out of the seed crystal box upwards, the other ends of the first rotating shaft and the second rotating shaft are provided with saw-tooth shapes, and the other ends of the two rotating shafts are meshed with each other.

The furnace cover is characterized by further comprising a lifting mechanism, wherein the lifting mechanism comprises a base, a lifting rod, a cross rod and a vertical rod, the lower end of the lifting rod is arranged on the base, the lower end of the vertical rod is arranged on the upper surface of the furnace cover, the left end of the cross rod is connected with the upper end of the lifting rod, the right end of the cross rod is connected with the upper end of the vertical rod, and the lifting rod is connected with the furnace body control system.

Preferably, the conveying device comprises a powder box, a conveying pipe and a solid particle conveying pump, wherein the powder box is arranged outside the furnace body, one end of the conveying pipe is connected with the lower part of the side wall of the powder box, the other end of the conveying pipe penetrates through the furnace body and the side wall of the crucible and is positioned inside the crucible, the solid particle conveying pump is connected to the conveying pipe, and the solid particle conveying pump is connected with the furnace body control system.

The silicon carbide powder synthesizing method using the equipment comprises the following steps:

S1: taking 100-200 mesh silicon carbide seed crystals, placing the silicon carbide seed crystals into the seed crystal box, and simultaneously filling carbon powder into the transmission device;

S2: filling a cosolvent containing Si and carbon powder into the crucible, assembling the seed crystal box filled with silicon carbide seed crystals on the upper part of the crucible, and covering a furnace cover on the furnace body;

S3: the furnace body control system controls the heating device to work, the induction coil in the furnace body starts heating, the thermometer detects the temperature in the crucible in real time, detected temperature data are transmitted to the furnace body control system in real time, the temperature of the upper part of the crucible reaches 1750-1850 ℃ in 4-5h, the temperature of the lower part of the crucible reaches 1200-1400 ℃, the upper part of the crucible is a high temperature area, the lower part of the crucible is a cooling area, materials in the crucible are dissolved into liquid, the temperature of the crucible gradually decreases from top to bottom, when the temperature of the high temperature area of the crucible reaches 1750-1850 ℃, the temperature of the cooling area of the crucible reaches 1200-1400 ℃, the heating device is controlled to maintain the current temperature, at the moment, the materials in the crucible are dissolved into liquid, the furnace body control system controls the transmission device to start, carbon powder in the transmission device is transmitted into the crucible and is added into the solution to form a solution in a carbon supersaturated state, and after the transmission device works for 8-10h, the control system controls the transmission device to stop working;

S4: controlling the discharging mechanism to be opened in a staged manner, opening the discharging mechanism once every 18-22min, wherein the opening time is 10-20s each time, when the discharging mechanism is opened, the silicon carbide crystal seeds in the crystal seed box are scattered into the solution in the crucible, the silicon carbide crystal seeds grow in a high temperature area under the action of buoyancy due to the supersaturation state of the solution, the grain size and the weight are gradually increased along with the continuous growth of the silicon carbide crystal seeds to form silicon carbide powder with large grain size, when the gravity of the silicon carbide powder is larger than the buoyancy, the silicon carbide powder gradually drops from the high temperature area to the low temperature area, the grain size growth rate of the silicon carbide powder is gradually slowed down to 0, and finally the silicon carbide powder drops in a cooling area at the bottom of the crucible for cooling;

S5: after the synthesis time of the silicon carbide powder reaches 10-12h, reducing carbon elements in the solution, wherein at the moment, the furnace body control system controls the transmission device to be started, and continuously conveying carbon powder into the crucible at the conveying speed of 5-10g/min;

S6: and (3) repeating the steps S4-S5 and 18-22h, completing the synthesis of the silicon carbide powder, controlling the heating device to stop working by the furnace body control system, cooling for 5-10h, controlling the lifting device to drive the furnace cover to lift by the furnace body control system, opening the furnace body, taking out the crucible, separating the seed crystal box from the upper part of the crucible, and pouring out the silicon carbide powder.

Compared with the prior art, the invention has the following advantages:

1) The invention can control the grain size of the silicon carbide powder, and in the charging procedure of the silicon carbide seed crystal, the silicon carbide seed crystals with different grain sizes can be adopted to cooperate with the silicon carbide powder growth process, thereby controlling the grain size of the silicon carbide and improving the large grain size effective productivity of the silicon carbide powder. Compared with the traditional silicon carbide powder synthesis process, the silicon carbide powder produced by the invention does not need to be crushed, and can directly produce the yield of the required target particle size.

2) The silicon carbide single crystal is adopted to synthesize the silicon carbide powder, and the growth process is less influenced by gravity, so that the formed silicon carbide powder is spherical, the bulk density of the silicon carbide powder is increased, and thicker silicon carbide crystals can be grown by adopting the silicon carbide powder in the same crucible volume.

3) The device is simple, low in cost and simple in control method.

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.

Drawings

FIG. 1 is a schematic perspective view of a silicon carbide powder synthesizing apparatus according to one embodiment of the invention;

FIG. 2 is a schematic cross-sectional view of a silicon carbide powder synthesizing apparatus according to an embodiment of the invention;

FIG. 3 is a schematic view of a partially enlarged structure of a silicon carbide powder synthesizing apparatus according to an embodiment of the invention;

FIG. 4 is a schematic view showing an open state of a discharge plate of a silicon carbide powder synthesizing apparatus according to an embodiment of the invention;

FIG. 5 is a schematic view showing a closing state of a discharge plate of a silicon carbide powder synthesizing apparatus according to an embodiment of the invention;

FIG. 6 is a schematic view of a discharge plate structure of a silicon carbide powder synthesizing apparatus according to one embodiment of the invention;

FIG. 7 is a schematic view of a seed box structure of a silicon carbide powder synthesizing apparatus according to one embodiment of the invention.

Reference numerals:

1000-silicon carbide powder synthesizing equipment;

100-furnace body; 111-a temperature measuring hole; 112-a growth chamber; 113-a support table;

120-furnace cover;

130-a transmission device; 131-a powder box; 132-a feed delivery tube;

140-a cooling device; 141-a cooling circulation line;

150-a discharging mechanism; 151-stepper motor; 152-a first rotation axis; 153-a second rotation axis; 154: a discharge plate; 155-a baffle; 156-rack;

160-lifting device; 161-lifting rod; 162-cross bar; 163-vertical bars;

170-a furnace body control system;

200-crucible;

300-seed box; 310-a first discharge hole;

400-induction coil;

500-base.

Detailed Description

Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.

The following disclosure provides many different embodiments, or examples, for implementing different structures of the invention. In order to simplify the present disclosure, components and arrangements of specific examples are described below. Of course, they are merely examples and are not of interest. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art will recognize the applicability of other processes and/or the use of other materials.

Referring to fig. 1 to 5, a silicon carbide powder synthesizing apparatus 1000 according to an embodiment of the present invention is described below, and referring to fig. 1 and 2, the apparatus includes a furnace body 100, a furnace cover 120, a seed box 300, a transmission device 130, a cooling device 140, a heating device, and a furnace body control system, the furnace body control system is disposed in an electric control device 170, a growth chamber 112 is formed in the furnace body 100, a support table 113 is disposed in the growth chamber 112, a crucible 200 is disposed on the support table 113, temperature measuring holes 111 are coaxially formed on a side wall of the furnace body 100 and a side wall of the crucible 200 for observing a temperature in the crucible 200, the temperature measuring holes 111 on the side wall of the crucible 200 are sealed by quartz glass, and of course the temperature measuring holes 111 on the side wall of the furnace body 100 can also be sealed by quartz glass to reduce heat dissipation in the furnace body 100; the furnace cover 120 is assembled at the upper part of the furnace body 100 for sealing the furnace body 100; the seed crystal box 300 is assembled on the upper part of the crucible 200, and the bottom of the seed crystal box 300 is provided with a discharging mechanism 150; the conveying device 130 is connected with the growth chamber 112 and is used for conveying carbon powder into the crucible 200; the cooling device 140 is used for cooling the furnace body 100; the heating device is an induction coil 400, the induction coil 400 is divided into three groups, namely an upper group, a middle group and a lower group, which are respectively surrounded on the upper part, the middle part and the lower part of the crucible 200 and are used for heating the crucible 200, the upper group, the middle group and the lower group of coils are all connected with a furnace body control system in the furnace body control system, the furnace body control system is used for respectively controlling the heating power of the three groups of coils, specifically, the three groups of induction coils 400 are used for heating the upper, middle and lower parts of the crucible 200, the number of the induction coils 400 on the upper part of the crucible 200 is n1, the number of the induction coils 400 on the middle part of the crucible 200 is n2, the number of the induction coils 400 on the lower part of the crucible 200 is n3, n1 is more than n2 is more than n3, and the furnace body control system is used for controlling the transmission device 130, the cooling device 140 and the heating device to work or stop working.

Referring to fig. 1 and 2, in some embodiments, the side walls of the furnace body 100 and the furnace cover 120 of the present embodiment are hollow structures, and the cooling device 140 is connected to the hollow structures of the furnace body 100 and the furnace cover 120, respectively, through a cooling circulation line 141. Specifically, the cooling water in the cooling device 140 of the embodiment enters the hollow structures of the furnace body 100 and the furnace cover 120 from the cooling circulation pipeline 141, so as to cool the side walls of the furnace body 100 and the furnace cover 120, and prevent production accidents caused by overhigh temperatures of the furnace body 100 and the furnace cover 120.

Referring to fig. 1, in some embodiments, temperature measuring holes 111 of the present embodiment are formed at upper and lower portions of a side wall of a crucible 200 and a furnace body 100, and infrared thermometers are correspondingly installed at the temperature measuring holes 111 on the side wall of the furnace body 100 and used for detecting the temperature in the crucible 200 in real time, and the infrared thermometers are electrically connected with a furnace body control system. Specifically, the temperature measuring instrument can be erected on the side wall of the furnace body 100 through a supporting frame and is coaxially arranged with the temperature measuring hole 111.

Referring to fig. 2 to 5, in some embodiments, the discharging mechanism 150 of the present embodiment includes a first discharging hole 310, a discharging plate 154, and a rotating member, and referring to fig. 7, the first discharging holes 310 are uniformly distributed at the bottom of the seed box 300; the discharge plate 154 is arranged at the bottom of the inner side of the seed crystal box 300, referring to fig. 6, the discharge plate 154 is a hollow plate, baffle plates 155 are uniformly distributed on the hollow plate, specifically, the diameter of the baffle plates 155 is the same as or slightly larger than that of the first discharge holes 310, the rotating parts are respectively connected with the furnace body control system and the discharge plate 154, the furnace body control system drives the discharge plate 154 to rotate through the rotating parts, and the discharge plate 154 has two states:

In the first state, the rotating component drives the discharging plate 154 to rotate, and the rotating component drives the discharging plate 154 to rotate, so that the first discharging holes 310 and the baffle 155 are staggered, and at the moment, the discharging plate 154 is in an open state, as shown in fig. 4;

In the second state, the rotating component drives the discharging plate 154 to rotate, so that the first discharging hole 310 and the baffle 155 are overlapped, and at this time, the discharging plate 154 is in a closed state, as shown in fig. 5;

During operation, silicon carbide seed crystals are contained in the seed crystal box 300, when the discharging plate 154 is in an open state, namely, the first discharging hole 310 and the baffle 155 are staggered, at this time, the silicon carbide seed crystals in the seed crystal box 300 can fall into the solution in the crucible 200 through the first discharging hole 310, and synthesis of silicon carbide powder is performed. When the silicon carbide seed crystal is not required to be conveyed into the crucible 200, the furnace body control system can control the discharge plate 154 to be in a closed state, namely, the first discharge hole 310 is overlapped with the baffle 155, the first discharge hole 310 is blocked by the baffle 155, the silicon carbide seed crystal cannot fall into the crucible 200, and the control method is simple and easy to implement.

Referring to fig. 2, in some embodiments, the rotating part of the present embodiment includes a stepping motor 151, a first rotating shaft 152 and a second rotating shaft 153, the stepping motor 151 is installed on the outside of the furnace body 100 through a bracket 156, the stepping motor 151 is connected with a furnace body control system, one end of the first rotating shaft 152 is connected with an output shaft of the stepping motor 151, the other end extends into the growth chamber 112, one end of the second rotating shaft 153 is installed at the center of the discharging plate 154, the other end extends upward out of the seed box 300, the other ends of the first rotating shaft 152 and the second rotating shaft 153 are both provided with a saw tooth shape, and the other ends of the two rotating shafts are engaged with each other. In this embodiment, the rotation of the discharging plate 154 is controlled by clicking and rotating the shaft, so that the discharging plate 154 is in an opened or closed state, and other structures can be adopted to realize the function of opening or closing the discharging.

Referring to fig. 2, in some embodiments, the present embodiment further includes a lifting mechanism, the lifting mechanism includes a base 500, a lifting rod 161, a cross rod 162 and a vertical rod 163, the lifting rod 161 and the support 156 of the stepper motor 151 are all installed on the base 500, the vertical rod 163 is installed on the upper surface of the furnace cover 120 and is located at the center position of the furnace cover 120, the left end (left side in fig. 2) of the cross rod 162 is connected to the upper end of the lifting rod 161, the right end of the cross rod 162 is connected to the upper end of the vertical rod 163, and the lifting rod 161 is connected to the furnace body control system. The lifting mechanism is arranged in the embodiment, and the main reason is that the furnace cover 120 is convenient for a worker to remove or cover the furnace cover from the upper part of the furnace body 100, so that the furnace body 100 is opened or closed, the worker can realize the opening or closing of the furnace body 100 only by controlling the lifting rod 161 to ascend or descend through the furnace body control system, time and labor are saved, and the working efficiency is improved. The lift bar 161 is preferably an electric telescopic bar in this embodiment, although other lift bars 161, either pneumatic or hydraulic, may be selected.

Referring to fig. 2, in some embodiments, the conveying device 130 of the present embodiment includes a powder box 131, a conveying pipe 132, and a solid particle conveying pump (not shown in the drawings), where the powder box 131 is disposed outside the furnace body 100, one end of the conveying pipe 132 is connected to a lower portion of a sidewall of the powder box 131, and the other end of the conveying pipe passes through the furnace body 100 and a sidewall of the crucible 200 to be located inside the crucible 200, the solid particle conveying pump is connected to the conveying pipe 132, and the solid particle conveying pump is connected to a furnace body control system. In this embodiment, the powder box 131 is used for containing carbon powder, when carbon powder needs to be added into the crucible 200, the furnace body control system controls the solid particle delivery pump to work, and the carbon powder in the powder box 131 is delivered into the solution in the crucible 200 through the delivery pipe 132 under the action of the solid particle delivery pump, so that the addition of the carbon powder is completed. The solid particle transfer pump of this embodiment is preferably a screw pump.

The silicon carbide powder synthesis method based on the equipment comprises the following steps:

S1: taking 100-200 mesh silicon carbide seed crystals, placing the silicon carbide seed crystals into a seed crystal box 300, and simultaneously filling carbon powder into a powder box 131;

s2: filling a cosolvent containing Si and carbon powder into the crucible 200, and assembling a seed crystal box 300 filled with silicon carbide seed crystals on the upper part of the crucible 200 to seal the crucible 200, controlling a lifting device 160 to descend through a furnace body control system to drive a furnace cover 120 to descend, so that the furnace cover 120 covers the upper part of the furnace body 100 to seal the furnace body 100;

S3: the furnace body control system controls the heating device to work, namely the induction coil 400 is electrified, the induction coil 400 in the furnace body 100 starts heating, meanwhile, the thermometer detects the temperature in the crucible 200 in real time and transmits the detected temperature data to the furnace body control system in real time, the temperature in the upper part (high temperature area) of the crucible 200 reaches 1750-1850 ℃ in 4-5 hours, the temperature in the lower part (cooling area) of the crucible 200 reaches 1200-1400 ℃, the material in the crucible 200 is dissolved into liquid, the temperature of the crucible 200 gradually decreases from top to bottom, when the temperature in the high temperature area of the crucible 200 reaches 1750-1850 ℃ and the temperature in the low temperature area of the crucible 200 reaches 1200-14000 ℃, the heating device is controlled to maintain the current temperature, at this time, the furnace body control system controls the transmission device 130 to start, the carbon powder in the transmission device 130 is transmitted into the crucible 200 through the material pipe 132 and added into the solution to form a solution in a carbon supersaturated state, and after the transmission device 130 works for 8-10 hours, the furnace body control system controls the transmission device 130 to stop working;

S4: the discharging mechanism 150 is controlled to be opened in a staged manner, the discharging mechanism is opened every 18-22min, the opening time is 10-20s each time, when the discharging mechanism 150 is opened, silicon carbide crystal seeds in the crystal seed box 300 are scattered into solution in the crucible 200, the silicon carbide crystal seeds grow in a high temperature area under the action of buoyancy due to the supersaturation state of the solution, the grain size and the weight become larger gradually along with the continuous growth of the silicon carbide crystal seeds to form silicon carbide powder with large grain size, and the silicon carbide single crystal is single crystal seed crystal, so that the powder density is 3.2g/cm ³; when the gravity of the silicon carbide powder is greater than the buoyancy, the silicon carbide powder gradually falls from a high temperature area to a low temperature area, the grain size growth rate of the silicon carbide powder gradually becomes slow until the grain size is 0, and finally the silicon carbide powder falls into a cooling area at the bottom of the crucible 200 for cooling;

s5: after the synthesis time of the silicon carbide powder reaches 10-12h, the carbon element in the solution is reduced, at the moment, the furnace body control system controls the transmission device 130 to be started, and carbon powder is continuously conveyed into the crucible 200 at the conveying speed of 5-10g/min;

S6: and (3) repeating the steps S4-S5 and 18-22h, completing the synthesis of the silicon carbide powder, controlling the heating device to stop working by the furnace body control system, driving the furnace cover 120 to ascend by the lifting device 160 by the furnace body control system after cooling for 5-10h, opening the furnace body 100, taking out the crucible 200, separating the seed crystal box 300 from the upper part of the crucible 200, and pouring out the silicon carbide powder.

Example 1

S1: taking 100-mesh silicon carbide seed crystals, placing the silicon carbide seed crystals into a seed crystal box 300, and simultaneously filling carbon powder into a powder box 131;

S2: a cosolvent Si _0.7Cr_0.3 and carbon powder are filled in the crucible 200, a seed crystal box 300 filled with silicon carbide seed crystal is assembled at the upper part of the crucible 200 to seal the crucible 200, and a furnace cover 120 is covered at the upper part of the furnace body 100 by controlling a lifting rod 161 to descend through a furnace body control system to seal the furnace body 100; of course, Si_XAl_1-X、Si_XTi_1-X、Si_XV_1-X、Si_XCr_1-X、Si_XNi_1-X、Si_XGa_1-X、Si_XGe_1-X and the like can also be selected as the cosolvent, and Si _0.7Cr_0.3 is preferred in the embodiment.

S3: the staff starts the heating device through the furnace control system, the induction coil 400 in the furnace 100 starts heating, in order to be convenient for description, the upper part in the crucible 200 is defined as a high temperature area, the lower part is defined as a cooling area, meanwhile, the infrared thermometer detects the temperatures of the high temperature area and the cooling area in the crucible 200 in real time, and transmits the detected temperatures to the furnace control system in real time, the temperature of the high temperature area of the crucible 200 reaches 1800 ℃ within 5 hours, the temperature of the crucible 200 gradually decreases from the high temperature area to the cooling area, the temperature gradient is 3 ℃/mm, the temperature of the cooling area of the crucible 200 is 1200 ℃, when the temperature of the high temperature area received by the furnace control system is 1800 ℃, the heating device is controlled to maintain the current temperature, at this time, the material in the crucible 200 is dissolved into liquid, the furnace control system controls the operation of the solid particle conveying pump, carbon powder in the powder box 131 is conveyed into the solution in the crucible 200 through the conveying pipe 132 under the action of the solid particle conveying pump, the solid particle conveying pump forms a solution in a carbon supersaturated state, and after the furnace body pump works for 9 hours, the control system controls the solid particle conveying pump to stop working;

S4: the furnace body control system controls the discharge plate 154 to be opened in stages, the discharge plate is opened once every 20min, the opening time length is 10s each time, and silicon carbide powder enters the synthesis stage, and the method is specifically as follows:

The furnace body control system controls the stepping motor 151 to rotate for a set angle, the stepping motor 151 rotates to drive the first rotating shaft 152 to rotate, the first rotating shaft 152 drives the second rotating shaft 153 to rotate, the discharging plate 154 is driven to rotate, the first discharging holes 310 and the baffle 155 are staggered, the discharging plate 154 is opened, silicon carbide seed crystals in the seed crystal box 300 are scattered into solution in the crucible 200 through the first discharging holes 310, after 10 seconds, the furnace body control system controls the stepping motor 151 to reset, the discharging plate 154 is closed, and the silicon carbide seed crystals stop falling into the solution; due to the supersaturation state of the solution, under the action of buoyancy, the silicon carbide seed crystal grows in a high-temperature region, the grain diameter and the weight become larger gradually along with the continuous growth of the silicon carbide seed crystal to form silicon carbide powder with large grain diameter, when the gravity of the silicon carbide powder is larger than the buoyancy, the silicon carbide powder gradually drops from the high-temperature region to a cooling region, the grain diameter growth rate of the silicon carbide powder becomes slow gradually until the grain diameter is 0, and finally the silicon carbide powder drops in the cooling region at the bottom of the crucible 200 to be cooled;

S5: after the synthesis time of the silicon carbide powder reaches 10 hours, the carbon element in the solution is reduced, at the moment, the furnace body control system controls the solid particle conveying pump to be started, and carbon powder is conveyed into the crucible 200 at the conveying speed of 5g/min;

S6: after repeating steps S4 to S5 for 20 hours, the silicon carbide powder is synthesized, the furnace body control system controls the heating device to stop working, controls the lifting rod 161 to lift after cooling for 5 hours, the furnace cover 120 lifts along with the lifting rod, the furnace body 100 is opened, a worker takes out the crucible 200, the seed crystal box 300 is separated from the upper part of the crucible 200, and the silicon carbide powder is poured out.

Because the temperature in the cooling zone of crucible 200 is low, there is sometimes no or little participation in the reaction of the solution in this zone, and therefore, it is necessary to screen the silicon carbide powder from the solution in the cooling zone through a screen, and finally obtain the silicon carbide powder.

Example 2

The method of this embodiment is the same as that of the embodiment, except that: in step S3, the crucible 200 is gradually reduced from the high temperature region to the cooling region, and the temperature gradient is 5 ℃/mm.

Example 3

The method of this embodiment is the same as that of the embodiment, except that: in step S3, the crucible 200 is gradually reduced from the high temperature region to the cooling region, and the temperature gradient is 10 ℃/mm.

Example 4

The method of this embodiment is the same as that of the embodiment, except that: the temperature of the cooling zone of the crucible 200 in step S3 was 1300 ℃.

Example 5

The method of this embodiment is the same as that of the embodiment, except that: the temperature of the cooling zone of the crucible 200 in step S3 was 1400 ℃.

The grain sizes of the silicon carbide powders obtained in the above examples are shown in the following table:

examples	Particle size (mesh)
		1	33-35
2	43-45
		3	55-59
4	20-22
		5	10-14

As is clear from the above examples, by controlling the temperature of the cooling region, the particle size of the silicon carbide powder can be controlled, because: the higher the temperature of the cooling zone is, the silicon carbide seed crystal grain diameter can continue to grow, the thickness and grain diameter of the obtained silicon carbide powder are larger, and the grain diameter of the silicon carbide powder can be controlled by controlling the temperature gradient, which is because: the larger the temperature gradient, the lower the height of the crucible 200, the shorter the time from the high temperature zone to the cooling zone, the shorter the growth time of the silicon carbide seed particle size, resulting in a small particle size of the finally formed silicon carbide powder. The silicon carbide powder produced by the invention can grow high-quality silicon carbide crystals.

Other components of the silicon carbide powder synthesizing apparatus 1000 and the synthesizing method according to the embodiment of the present invention, such as the stepping motor 151, the crucible 200, the solid particle transfer pump, etc., and the operation thereof, are known to those of ordinary skill in the art, and will not be described in detail herein.

In the description of the present 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", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; the device can be mechanically connected, electrically connected and communicated; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: many changes, modifications, substitutions and variations may be made to the embodiments without departing from the spirit and principles of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. The silicon carbide powder synthesizing equipment is characterized by comprising

The furnace body, the growth chamber is formed inside the furnace body, a crucible is placed in the growth chamber, the side wall of the furnace body and the side wall of the crucible are both coaxially provided with temperature measuring holes, and the temperature measuring holes on the side wall of the crucible are sealed by quartz glass;

the furnace cover is assembled on the upper part of the furnace body and is used for sealing the furnace body;

The seed crystal box is assembled at the upper part of the crucible, and a discharging mechanism is arranged at the bottom of the seed crystal box;

The conveying device is connected with the growth chamber and is used for conveying carbon powder into the crucible;

the cooling device is used for cooling the furnace body;

the heating device is an induction coil and is used for heating the crucible;

and the furnace body control system is used for controlling the transmission device, the cooling device and the heating device to work or stop working.

2. A silicon carbide powder synthesis apparatus as claimed in claim 1, wherein the side walls of the furnace body and the cover are hollow structures, and the cooling means is connected to the hollow structures of the furnace body and the cover respectively via cooling circulation pipes.

3. A silicon carbide powder synthesis apparatus according to claim 1, wherein the temperature measuring Kong Kaishe is provided on the upper and lower portions of the crucible and the side wall of the furnace body, and the temperature measuring holes in the side wall of the furnace body are provided with infrared thermometers for detecting the temperature in the crucible in real time, and the infrared thermometers are electrically connected to the furnace body control system.

4. A silicon carbide powder synthesis apparatus as claimed in claim 3, wherein the discharge mechanism comprises

The first discharging holes are uniformly distributed at the bottom of the seed crystal box;

The discharging plate is arranged at the bottom of the inner side of the seed crystal box, is a hollowed-out plate, and is uniformly provided with baffle plates;

5. A silicon carbide powder synthesis apparatus as claimed in claim 4, wherein the rotating member includes a stepping motor, a first rotating shaft and a second rotating shaft, the stepping motor is mounted outside the furnace body, the stepping motor is connected to the furnace body control system, one end of the first rotating shaft is connected to the output shaft of the stepping motor, the other end of the first rotating shaft extends into the growth chamber, one end of the second rotating shaft is mounted at the centre of the discharge plate, the other end of the second rotating shaft extends upward outside the seed box, the other ends of the first rotating shaft and the second rotating shaft are both provided with a saw-tooth shape, and the other ends of the two rotating shafts are engaged with each other.

6. A silicon carbide powder synthesis apparatus as claimed in claim 4, further comprising a lifting mechanism including a base, a lifting rod, a cross rod and a vertical rod, wherein the lower end of the lifting rod is mounted on the base, the lower end of the vertical rod is mounted on the upper surface of the furnace cover, the left end of the cross rod is connected to the upper end of the lifting rod, the right end of the cross rod is connected to the upper end of the vertical rod, and the lifting rod is connected to the furnace body control system.

7. A silicon carbide powder synthesis apparatus as claimed in claim 6, wherein the transfer means comprises a powder box, a transfer tube and a solid particle transfer pump, the powder box being disposed outside the furnace body, one end of the transfer tube being connected to a lower portion of a side wall of the powder box, the other end of the transfer tube passing through the furnace body and a side wall of the crucible to be located inside the crucible, the solid particle transfer pump being connected to the transfer tube, the solid particle transfer pump being connected to the furnace body control system.

8. A method of synthesizing silicon carbide powder using an apparatus as defined in any one of claims 3-7, comprising the steps of:

S3: the furnace body control system controls the heating device to be electrified, the induction coil in the furnace body starts to heat, meanwhile, the thermometer detects the temperature in the crucible in real time and transmits the detected temperature data to the furnace body control system in real time, the temperature of the upper part of the crucible reaches 1750-1850 ℃ in 4-5 hours, the temperature of the lower part of the crucible reaches 1200-1400 ℃, the upper part of the crucible is a high temperature area, the lower part of the crucible is a cooling area, materials in the crucible are dissolved into liquid, the temperature of the crucible gradually decreases from top to bottom, when the temperature of the high temperature area of the crucible reaches 1750-1850 ℃, the temperature of the cooling area of the crucible reaches 1200-1400 ℃, the heating device is controlled to maintain the current temperature, at this time, the materials in the crucible are dissolved into liquid, the furnace body control system controls the transmission device to start, carbon powder in the transmission device is transmitted into the crucible and is added into the solution to form a solution in a carbon supersaturated state, and after the transmission device works for 8-10 hours, the furnace body control system controls the transmission device to stop working;