A graphite crucible cover and a CVD graphene powder system

Abstract

The present invention relates to a graphite crucible cover and a CVD graphene system, wherein the graphite crucible cover comprises a detachably connected upper cover and a bottom plate; a heat insulation area is arranged in a cavity surrounded by the upper cover and the bottom plate. The present invention provides a graphite crucible cover, which effectively blocks heat transfer by arranging a heat insulation area inside the graphite crucible cover, and can play a good role in heat preservation for liquid copper inside the graphite crucible, thereby reducing the energy consumption of graphene powder manufacturing and saving costs.

Description

Technical Field

[0001] The invention belongs to the technical field of graphene powder manufacturing, relates to a graphite crucible cover, and in particular to a graphite crucible cover and a CVD graphene system. Background Art

[0002] The commonly used methods for preparing graphene powders at present include oxidation-reduction, liquid phase exfoliation, supercritical exfoliation and CVD methods. Among them, although the oxidation-reduction method can obtain graphene powders with fewer layers, the large amount of strong oxidants used in the preparation process not only seriously damages the crystal structure of graphene, resulting in a decrease in electrical and thermal conductivity, but also the discharge of waste liquid containing a large amount of strong acid and strong oxidants will seriously pollute the environment; in liquid phase exfoliation and supercritical exfoliation, although the graphite crystal structure can be well preserved, the number of layers is uncontrollable, the thickness is very large, and the thickness range is very wide.

[0003] Graphene powder prepared by CVD method is currently recognized as the best quality graphene material, which is of great significance to the development of downstream high-end applications. However, since the CVD method grows graphene powder by bubbling graphene in molten liquid copper, the copper liquid splashes seriously during the ventilation growth process, and the graphite crucible cover becomes an indispensable supporting product to prevent the copper liquid from splashing.

[0004] CN 105066694A discloses a graphite crucible cover, including a graphite crucible cover body made of natural graphite, the crucible cover body is a conical structure, the interior of the crucible cover is a conical cavity, four mutually symmetrical circular holes are arranged on the curved surface of the side of the crucible cover body, the circular holes connect the external air with the internal cavity of the crucible cover, the cone top of the crucible cover body is provided with a hook ring, and the cone vertex angle in the vertical section of the crucible cover body is an acute angle. Through the above method, the structure of the graphite crucible cover is simple, different from the ordinary flat crucible cover, the graphite crucible cover is a cavity cone shape, the cone vertex angle is set to an acute angle, and a through hole is arranged on the side of the cone, which can not only effectively prevent the heated object in the crucible from jumping out, but also ensure that the external air can freely enter and exit the graphite crucible for oxidation reaction, which is highly practical and has certain economic benefits and market prospects.

[0005] CN 215261160U relates to a crucible cover mechanism for a graphite crucible, comprising a crucible body and a crucible cover body, wherein the crucible cover body is correspondingly mounted above the crucible body, a mounting groove is provided on the lower end surface of the crucible cover body, a plurality of connecting seats are provided on the top of the mounting groove, a plurality of lower end surfaces of the connecting seats are provided with clamping grooves corresponding to the crucible body, a heat dissipation groove is provided on the upper end of the crucible cover body, a plurality of temperature regulating sheets are provided in the heat dissipation groove, a plurality of limiting grooves are provided on the inner wall of the heat dissipation groove corresponding to the plurality of temperature regulating sheets, a liquid discharge hole is provided at the center position of the bottom end of the crucible body, a positioning hole is provided at the center position of the top end of the crucible cover, a sealing rod is provided in the positioning hole, and a sealing tip is provided at the bottom end of the sealing rod corresponding to the liquid discharge hole; the design of the connecting seat facilitates installation; the design of the temperature regulating sheet strengthens heat dissipation; the design of the sealing rod facilitates liquid discharge.

[0006] In the above technical solution, due to the high thermal conductivity of graphite, the graphite crucible cover can quickly conduct and radiate the huge radiant heat generated by the high-temperature liquid copper in the crucible. In order to maintain a certain growth temperature, it is necessary to increase the heating power additionally, which will inevitably increase energy consumption.

[0007] Therefore, how to reduce energy consumption and improve the thermal insulation effect in the preparation of graphene powder is a technical problem that urgently needs to be solved in the field of graphene powder manufacturing technology. Summary of the invention

[0008] In view of the problems existing in the prior art, the present invention provides a graphite crucible cover and a CVD-made graphene system. By filling the cavity composed of the upper cover and the bottom plate with an insulating material with a low thermal conductivity to obtain an insulating zone, heat transfer can be effectively blocked, and the liquid copper inside the graphite crucible can be well insulated.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a graphite crucible cover, comprising an upper cover and a bottom plate that are detachably connected; a heat insulation area is provided in a cavity enclosed by the upper cover and the bottom plate.

[0011] The present invention provides a graphite crucible cover, which effectively blocks heat transfer by arranging a heat insulation area inside the graphite crucible cover, and can play a good heat preservation role for liquid copper inside the graphite crucible, thereby reducing the energy consumption of graphene powder manufacturing and saving costs.

[0012] Preferably, the insulation zone filling volume accounts for 60-90% of the cavity volume, for example, it can be 60%, 65%, 70%, 80%, 85% or 90%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0013] Preferably, the thermal insulation area is filled with thermal insulation material.

[0014] Preferably, the thermal insulation material comprises any one of alumina fiber, silica fiber, silicon carbide fiber, aluminum silicate fiber, mullite fiber, carbon fiber or expanded graphite, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of alumina fiber and silica fiber, a combination of silica fiber and silicon carbide fiber, a combination of silicon carbide fiber and aluminum silicate fiber, a combination of aluminum silicate fiber and mullite fiber, a combination of mullite fiber and carbon fiber, a combination of carbon fiber or expanded graphite, a combination of alumina fiber, silica fiber, silicon carbide fiber, a combination of silicon carbide fiber, aluminum silicate fiber, mullite fiber and carbon fiber, or a combination of silicon carbide fiber, aluminum silicate fiber, mullite fiber, carbon fiber or expanded graphite, preferably silica fiber.

[0015] The heat insulation area provided by the present invention plays a heat insulation role by filling the heat insulation material. The heat insulation material has a low thermal conductivity.

[0016] Preferably, a threaded structure is provided on the upper cover and the bottom plate for connection.

[0017] The upper cover and the bottom plate of the graphite crucible cover provided by the present invention are connected by threads, so as to facilitate disassembly.

[0018] Preferably, the upper cover comprises a top plate and a side ring.

[0019] Preferably, the top plate and the side ring have the same outer diameter.

[0020] The top plate and the side rings of the present invention are an integrated structure.

[0021] Preferably, a top plate air inlet is arranged at the center of the top plate, and a bottom plate air inlet is arranged at the center of the bottom plate.

[0022] Preferably, a low-temperature section air inlet pipe is connected between the top plate air inlet and the bottom plate air inlet.

[0023] Preferably, a threaded structure is provided on the top plate air inlet, the bottom plate air inlet and the low temperature section air inlet pipe for connection.

[0024] Preferably, a boss is provided at the bottom of the tube wall of the low-temperature section air inlet pipe, and the boss is horizontally fitted with the bottom plate.

[0025] Preferably, the diameter of the boss is 1.5-2.5 times the diameter of the low-temperature section intake pipe, for example, it can be 1.5 times, 1.7 times, 2 times, 2.2 times or 2.5 times, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] Preferably, a sealing gasket is provided between the boss and the bottom plate.

[0027] Preferably, the sealing gasket comprises an expanded graphite paper sealing gasket.

[0028] Preferably, a top plate exhaust port is provided on the top plate, and a bottom plate exhaust port is provided on the bottom plate.

[0029] The centers of the top plate exhaust port and the bottom plate exhaust port are on the same axis.

[0030] Preferably, an exhaust pipe is connected between the top plate exhaust port and the bottom plate exhaust port.

[0031] Preferably, a threaded structure is provided on the top plate exhaust port, the bottom plate exhaust port and the exhaust pipe for connection.

[0032] Preferably, a boss is provided at the bottom of the pipe wall of the exhaust pipe, and the boss is horizontally fitted with the bottom plate.

[0033] Preferably, the diameter of the boss is 1.5-2.5 times the diameter of the exhaust pipe, for example, it can be 1.5 times, 1.7 times, 2 times, 2.2 times or 2.5 times, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] Preferably, a sealing gasket is provided between the boss and the bottom plate.

[0035] The thickness of the gasket is 0.5-2 mm, for example, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm or 2 mm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0036] The outer diameter of the washer is the same as the outer diameter of the boss.

[0037] Preferably, the sealing gasket comprises an expanded graphite paper sealing gasket.

[0038] The low-temperature section air inlet pipe and the exhaust pipe provided by the present invention are both connected to the top plate and the bottom plate of the graphite crucible cover through a threaded structure, which is convenient for maintenance and disassembly.

[0039] The low-temperature section air inlet pipe and the boss on the bottom pipe wall are an integrated structure, and the exhaust pipe and the boss on the bottom pipe wall are an integrated structure.

[0040] The present invention provides bosses at the bottom of the low-temperature section air inlet pipe and the bottom of the exhaust pipe, and provides sealing gaskets between the bosses and the bottom plate, which can effectively prevent the graphite crucible cover from being vibrated due to the vibration generated by bubble bursting when the mixed gas is introduced into the liquid copper for growth, thereby preventing the parts of the graphite crucible cover from being loosened.

[0041] The graphite crucible cover provided by the present invention is provided with an air inlet pipe, which is divided into a low-temperature section air inlet pipe and a high-temperature section air inlet pipe. The upper part of the low-temperature section air inlet pipe is connected to an external air inlet pipeline, and the lower part is connected to the high-temperature section air inlet pipe. The lower part of the high-temperature section air inlet pipe leads to the interior of the graphite crucible. The entire air inlet pipe is divided into two parts for easy installation and disassembly.

[0042] The low-temperature section and the high-temperature section intake pipe are both made of graphite, and the length ratio of the low-temperature section intake pipe to the high-temperature section intake pipe is 1:1 to 1:5, for example, it can be 1:1, 1:2, 1:3, 1:4 or 1:5, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0043] Preferably, the top plate is provided with a small hole which penetrates the cavity.

[0044] The aperture of the small hole is 0.1 mm-5 mm, for example, it can be 0.1 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 4 mm or 5 mm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0045] The number of the small holes is 1-20, for example, 1, 5, 8, 10, 15 or 20.

[0046] The invention provides a small hole on the top plate of the crucible cover at any position for relieving pressure to prevent the gas inside the crucible cover cavity from expanding during high-temperature heating, thereby causing the crucible cover to crack.

[0047] In a second aspect, the present invention provides a CVD-processed graphene powder system, wherein the CVD-processed graphene powder system comprises the graphite crucible cover as described in the first aspect.

[0048] Preferably, the CVD graphene powder system includes a heating system.

[0049] The graphite crucible cover provided by the invention is placed inside the heating system during use, so that during the heating process, even if the splashed copper droplets contact the bottom plate, they will not solidify and can drip back into the graphite crucible.

[0050] The base plate is located inside the heating system.

[0051] The system refers to an equipment system, a device system or a production device.

[0052] According to the above technical scheme, the beneficial effects of the present invention are as follows:

[0053] (1) The present invention provides a graphite crucible cover, which effectively blocks heat transfer by arranging a heat insulation area inside the graphite crucible cover, thereby providing a good heat preservation effect for liquid copper inside the graphite crucible, reducing the energy consumption of graphene powder manufacturing and saving costs.

[0054] (2) The various components of the graphite crucible cover provided by the present invention are connected and fastened by a threaded structure, which is convenient for maintenance and disassembly.

[0055] (3) The present invention provides bosses at the bottom of the low-temperature section air inlet pipe and the bottom of the exhaust pipe, and provides sealing gaskets between the bosses and the bottom plate, which can effectively prevent the graphite crucible cover from being vibrated due to the vibration caused by bubble bursting when the mixed gas is introduced into the liquid copper for growth, thereby preventing the parts of the graphite crucible cover from being loosened.

[0056] (4) The graphite crucible cover provided by the present invention is placed inside the heating system during use, so that when a mixed gas is introduced into liquid copper to grow graphene powder, even if the splashing copper droplets contact the bottom plate, they will not solidify and can drip back into the graphite crucible. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is a schematic structural diagram of the graphite crucible cover provided by the present invention.

[0058] Figure 2 This is a schematic structural diagram of the exhaust pipe provided by the present invention being connected to the base plate.

[0059] Figure 3 This is a schematic diagram of the structure of the graphite crucible cover provided in Comparative Example 1.

[0060] Among them, 1-upper cover, 2-bottom plate, 3-insulation area, 4-low temperature section air intake pipe, 5-intake pipe boss, 6-exhaust pipe, 7-exhaust pipe boss, 8-heating system. DETAILED DESCRIPTION

[0061] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0062] Example 1

[0063] This embodiment provides a graphite crucible cover ( Figure 1 ) and CVD graphene powder system.

[0064] The graphite crucible cover comprises an upper cover 1 and a bottom plate 2 which are detachably connected. A threaded structure is arranged on the upper cover 1 and the bottom plate 2 for connection.

[0065] A heat insulation area 3 is arranged in the cavity enclosed by the upper cover 1 and the bottom plate 2. The volume of the heat insulation area 3 is 60% of the internal volume of the cavity. The heat insulation area 3 is filled with alumina fibers as a heat insulation material.

[0066] The upper cover 1 includes a top plate and a side ring, the top plate and the side ring have the same outer diameter. The top plate is provided with small holes penetrating the cavity, the aperture of the small holes is 2.5 mm, and the number of the small holes is 10.

[0067] A top plate air inlet is arranged at the center of the top plate, and a bottom plate air inlet is arranged at the center of the bottom plate 2; a low-temperature section air inlet pipe 4 is connected between the top plate air inlet and the bottom plate air inlet; a threaded structure is arranged on the top plate air inlet, the bottom plate air inlet and the low-temperature section air inlet pipe 4 for connection.

[0068] A boss 5 is provided at the bottom of the wall of the low-temperature section air inlet pipe 4, and the boss 5 and the bottom plate 2 are located at the same horizontal plane. The diameter of the boss 5 is twice the diameter of the low-temperature section air inlet pipe 4. An expanded graphite paper sealing gasket is provided between the boss 5 and the bottom plate 2.

[0069] The top plate is provided with a top plate exhaust port, and the bottom plate 2 is provided with a bottom plate exhaust port; an exhaust pipe 6 is connected between the top plate exhaust port and the bottom plate exhaust port; a threaded structure is provided on the top plate exhaust port, the bottom plate exhaust port and the exhaust pipe 6 for connection.

[0070] A boss 7 is provided at the bottom of the exhaust pipe 6, and the boss 7 is located at the same horizontal plane as the bottom plate 2. The diameter of the boss 7 is twice the diameter of the exhaust pipe 6. An expanded graphite paper sealing gasket is provided between the boss 7 and the bottom plate 2.

[0071] The CVD graphene powder system includes a heating system 8 and the graphite crucible cover. The bottom plate 2 is arranged inside the heating system 8.

[0072] The graphite crucible cover can effectively block heat transfer and play a good role in heat preservation for the liquid copper inside the crucible. When the copper mass in the crucible is constant and the heating power is 5KW, the temperature of the liquid copper in the crucible is 1280° C. At the same time, in the process of growing graphene powder by introducing mixed gas into the liquid copper, the splashed copper droplets will not solidify when contacting the bottom plate, and will be completely returned to the graphite crucible. There is no adhesion of copper on the bottom plate, so that the exhaust will not be blocked.

[0073] Example 2

[0074] This embodiment provides a graphite crucible cover ( Figure 1 ) and CVD graphene powder system.

[0075] The graphite crucible cover comprises an upper cover 1 and a bottom plate 2 which are detachably connected. A threaded structure is arranged on the upper cover 1 and the bottom plate 2 for connection.

[0076] The cavity enclosed by the upper cover 1 and the bottom plate 2 is provided with a heat insulation area 3. The volume of the heat insulation area 3 is 70% of the internal volume of the cavity. The heat insulation area 3 is filled with silicon dioxide fiber as a heat insulation material.

[0077] The upper cover 1 includes a top plate and a side ring, the top plate and the side ring have the same outer diameter. The top plate is provided with small holes penetrating the cavity, the aperture of the small holes is 0.1 mm, and the number of the small holes is 20.

[0078] A top plate air inlet is arranged at the center of the top plate, and a bottom plate air inlet is arranged at the center of the bottom plate 2; a low-temperature section air inlet pipe 4 is connected between the top plate air inlet and the bottom plate air inlet; a threaded structure is arranged on the top plate air inlet, the bottom plate air inlet and the low-temperature section air inlet pipe 4 for connection.

[0079] A boss 5 is provided at the bottom of the tube wall of the low temperature section air inlet pipe 4, and the boss 5 is located at the same horizontal plane as the bottom plate 2. The diameter of the boss 5 is 1.5 times the diameter of the low temperature section air inlet pipe 4. An expanded graphite paper sealing gasket is provided between the boss 5 and the bottom plate 2.

[0080] The top plate is provided with a top plate exhaust port, and the bottom plate 2 is provided with a bottom plate exhaust port; an exhaust pipe 6 is connected between the top plate exhaust port and the bottom plate exhaust port; a threaded structure is provided on the top plate exhaust port, the bottom plate exhaust port and the exhaust pipe 6 for connection.

[0081] The exhaust pipe 6 ( Figure 2 ) is provided with a boss 7 at the bottom of the pipe wall, and the boss 7 and the bottom plate 2 are located at the same horizontal plane. The diameter of the boss 7 is 1.5 times the diameter of the exhaust pipe 6. An expanded graphite paper sealing gasket is provided between the boss 7 and the bottom plate 2.

[0082] The CVD graphene powder system includes a heating system 8 and the graphite crucible cover. The bottom plate 2 is arranged inside the heating system 8.

[0083] The graphite crucible cover can effectively block heat transfer and play a good role in heat preservation for the liquid copper inside the crucible. When the copper mass in the crucible is constant and the heating power is 5KW, the temperature of the liquid copper in the crucible is 1283° C. At the same time, in the process of growing graphene powder by introducing mixed gas into the liquid copper, the splashed copper droplets will not solidify when contacting the bottom plate, and will be completely returned to the graphite crucible. There is no adhesion of copper on the bottom plate, so that the exhaust will not be blocked.

[0084] Example 3

[0085] This embodiment provides a graphite crucible cover ( Figure 1 ) and CVD graphene powder system.

[0086] The graphite crucible cover comprises an upper cover 1 and a bottom plate 2 which are detachably connected. A threaded structure is arranged on the upper cover 1 and the bottom plate 2 for connection.

[0087] A heat insulation area 3 is arranged in the cavity enclosed by the upper cover 1 and the bottom plate 2. The volume of the heat insulation area 3 is 80% of the internal volume of the cavity. The heat insulation area 3 is filled with silicon carbide fibers as heat insulation material.

[0088] The upper cover 1 includes a top plate and a side ring, wherein the top plate has the same outer diameter as the side ring. A small hole penetrating the cavity is arranged on the top plate, wherein the diameter of the small hole is 5 mm, and the number of the small hole is 1.

[0089] A top plate air inlet is arranged at the center of the top plate, and a bottom plate air inlet is arranged at the center of the bottom plate 2; a low-temperature section air inlet pipe 4 is connected between the top plate air inlet and the bottom plate air inlet; a threaded structure is arranged on the top plate air inlet, the bottom plate air inlet and the low-temperature section air inlet pipe 4 for connection.

[0090] A boss 5 is provided at the bottom of the tube wall of the low temperature section air inlet pipe 4, and the boss 5 is located at the same horizontal plane as the bottom plate 2. The diameter of the boss 5 is 2.5 times the diameter of the low temperature section air inlet pipe 4. An expanded graphite paper sealing gasket is provided between the boss 5 and the bottom plate 2.

[0091] The top plate is provided with a top plate exhaust port, and the bottom plate 2 is provided with a bottom plate exhaust port; an exhaust pipe 6 is connected between the top plate exhaust port and the bottom plate exhaust port; a threaded structure is provided on the top plate exhaust port, the bottom plate exhaust port and the exhaust pipe 6 for connection.

[0092] The exhaust pipe 6 ( Figure 2 ) is provided with a boss 7 at the bottom of the pipe wall, and the boss 7 is located at the same horizontal plane as the bottom plate 2. The diameter of the boss 7 is 2.5 times the diameter of the exhaust pipe 6. An expanded graphite paper sealing gasket is provided between the boss 7 and the bottom plate 2.

[0093] The CVD graphene powder system includes a heating system 8 and the graphite crucible cover. The bottom plate 2 is arranged inside the heating system 8.

[0094] The graphite crucible cover can effectively block heat transfer and play a good role in heat preservation for the liquid copper inside the crucible. When the copper mass in the crucible is constant and the heating power is 5KW, the temperature of the liquid copper in the crucible is 1285° C. At the same time, when the mixed gas is introduced into the liquid copper to grow graphene powder, the splashed copper droplets will not solidify when they contact the bottom plate, and will be completely returned to the graphite crucible. There is no adhesion of copper on the bottom plate, so that the exhaust will not be blocked.

[0095] Example 4

[0096] This embodiment provides a graphite crucible cover ( Figure 1 ) and CVD graphene powder system. Except that the diameter of the low temperature section intake pipe boss 5 is 1.1 times the diameter of the low temperature section intake pipe 4, and the diameter of the exhaust pipe boss 7 is 1.1 times the diameter of the exhaust pipe 6, the rest is the same as Example 1.

[0097] When mixed gas is introduced into liquid copper to grow graphene powder, bubbles burst and violent vibrations will occur. The combined area between the boss and the bottom plate of the crucible cover is too small to provide effective reinforcement. The threaded connections of the exhaust pipe and the air intake pipe will loosen due to the violent vibrations, causing them to fall off. The threaded connection between the bottom plate of the crucible cover and the side ring of the upper cover will also loosen due to the vibration, and may even cause the bottom plate to fall off.

[0098] Example 5

[0099] This embodiment provides a graphite crucible cover and a CVD graphene powder system, which is the same as Embodiment 1 except that the exhaust pipe has no boss and there is no expanded graphite paper sealing gasket between the exhaust pipe and the bottom plate.

[0100] When a mixed gas is introduced into liquid copper to grow graphene powder, vibration is generated due to the bursting of bubbles, and various parts of the graphite crucible cover provided in this embodiment are easily vibrated and loosened.

[0101] Example 6

[0102] This embodiment provides a graphite crucible cover and a system for preparing graphene powder by CVD method, which is the same as that of Embodiment 1 except that the bottom plate is located outside the heating system.

[0103] During the heating process, a large amount of solid copper is easily adhered to the bottom plate of the graphite crucible cover provided in this embodiment.

[0104] Example 7

[0105] This embodiment provides a graphite crucible cover and a CVD graphene powder system, which is the same as Embodiment 1 except that the thermal insulation material is replaced with carbon fiber.

[0106] When the mass of copper in the crucible is constant and the heating power is 5KW, the temperature of the liquid copper in the crucible is 1272℃.

[0107] Example 8

[0108] This embodiment provides a graphite crucible cover and a CVD graphene powder system, which is the same as Embodiment 1 except that the thermal insulation material is replaced with expanded graphite.

[0109] When the mass of copper in the crucible is constant and the heating power is 5KW, the temperature of the liquid copper in the crucible is 1268℃.

[0110] Comparative Example 1

[0111] This comparative example provides a graphite crucible cover ( Figure 3 ) and CVD graphene powder system.

[0112] The graphite crucible cover comprises an upper cover, and the upper cover comprises a top plate and a side ring, and the top plate has the same outer diameter as the side ring.

[0113] A top plate air inlet is arranged at the center of the top plate, and the top plate air inlet is connected to an air inlet pipe. A top plate exhaust port is arranged on the top plate, and the top plate exhaust port is connected to an exhaust pipe.

[0114] The graphite crucible cover provided in this comparative example adopts an inverted cup-shaped structure composed of a top plate and a graphite ring to reduce the problem of rapid heat transmission and large-scale heat loss caused by the high thermal conductivity of graphite. However, the high-temperature liquid copper generates huge heat radiation, and the inherent high-efficiency heat conduction and high-efficiency heat radiation characteristics of graphite make the thermal insulation effect unsatisfactory. Compared with Example 1, when the copper mass in the crucible is constant and the heating power is 5KW, the temperature of the liquid copper in the crucible is 1240°C.

[0115] At the same time, since most of the internal space of the inverted cup-shaped structure composed of the top plate and the graphite ring is in the non-heating zone, when a mixed gas is introduced into liquid copper to grow graphene powder, the splashing small copper droplets drill into the graphite micropores. Then, as the copper droplets continue to splash, the copper droplets in the non-heating zone inside the crucible cover continue to condense and bond, eventually resulting in a large amount of solid copper bonding to the graphite crucible cover, and causing the exhaust of the graphite crucible cover to be blocked.

[0116] Comparative Example 2

[0117] This comparative example provides a graphite crucible cover and a CVD graphene powder system, which is the same as Example 1 except that there is no insulation zone, that is, the insulation zone is replaced with graphite.

[0118] Since high-temperature liquid copper produces huge heat radiation, graphite has high thermal conductivity and high-efficiency heat radiation characteristics. The insulation effect of the liquid metal in the graphite crucible in this comparative example is not ideal. When the copper mass in the crucible is constant and the heating power is 5KW, the temperature of the liquid copper in the crucible is 1220°C.

[0119] The present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A graphite crucible cover, characterized in that: The graphite crucible cover comprises a detachably connected upper cover and a bottom plate; a heat insulation area is provided in the cavity surrounded by the upper cover and the bottom plate; The upper cover comprises a top plate and a side ring; the top plate is provided with small holes penetrating the cavity; the aperture of the small holes is 0.1 mm-5 mm; the number of the small holes is 1-20; A top plate air inlet is provided at the center of the top plate, and a bottom plate air inlet is provided at the center of the bottom plate; a low-temperature section air inlet pipe is connected between the top plate air inlet and the bottom plate air inlet; a first boss is provided at the bottom of the tube wall of the low-temperature section air inlet pipe, and the first boss is horizontally attached to the bottom plate; a first sealing gasket is provided between the first boss and the bottom plate; The top plate is provided with a top plate exhaust port, and the bottom plate is provided with a bottom plate exhaust port; an exhaust pipe is connected between the top plate exhaust port and the bottom plate exhaust port; A second boss is arranged at the bottom of the pipe wall of the exhaust pipe, and the second boss is horizontally fitted with the bottom plate; a second sealing gasket is arranged between the second boss and the bottom plate.

2. The graphite crucible cover according to claim 1, characterized in that: The volume of the thermal insulation zone accounts for 60-90% of the volume of the cavity.

3. The graphite crucible cover according to claim 1, characterized in that: The heat insulation area is filled with heat insulation material.

4. The graphite crucible cover according to claim 3, characterized in that: The thermal insulation material includes any one of alumina fiber, silicon dioxide fiber, silicon carbide fiber, aluminum silicate fiber, mullite fiber, carbon fiber or expanded graphite, or a combination of at least two thereof.

5. The graphite crucible cover according to claim 4, characterized in that: The thermal insulation material is silica fiber.

6. The graphite crucible cover according to claim 1, characterized in that: The upper cover and the bottom plate are provided with a thread structure for connection.

7. The graphite crucible cover according to claim 1, characterized in that: The top plate has the same outer diameter as the side ring.

8. The graphite crucible cover according to claim 1, characterized in that: The top plate air inlet, the bottom plate air inlet and the low temperature section air inlet pipe are provided with threaded structures for connection.

9. The graphite crucible cover according to claim 1, characterized in that: The diameter of the first boss is 1.5-2.5 times the diameter of the low-temperature section intake pipe.

10. The graphite crucible cover according to claim 1, characterized in that: The first sealing gasket comprises an expanded graphite paper sealing gasket.

11. The graphite crucible cover according to claim 1, characterized in that: The top plate exhaust port, the bottom plate exhaust port and the exhaust pipe are provided with threaded structures for connection.

12. The graphite crucible cover according to claim 1, characterized in that: The diameter of the second boss is 1.5-2.5 times the diameter of the exhaust pipe.

13. The graphite crucible cover according to claim 1, characterized in that: The second sealing gasket comprises an expanded graphite paper sealing gasket.

14. A CVD graphene powder system, characterized in that: The CVD graphene powder system comprises the graphite crucible cover as described in any one of claims 1-13.

15. The CVD graphene powder system according to claim 14, characterized in that: The CVD graphene powder system includes a heating system.

16. The CVD graphene powder system according to claim 15, characterized in that: The graphite crucible cover is located inside the heating system.

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