Multi-airflow alternating temperature calcining device for ultra-long nitride single crystal nanofibers

Abstract

The invention relates to a multi-airflow alternating temperature calcining device for ultra-long nitride single crystal nanofibers. The multi-airflow alternating temperature calcining device comprises a reaction furnace; the mechanical vacuum pressure gauge and the exhaust port are arranged at the top of the reaction furnace; the reaction furnace chamber is arranged in the reaction furnace; the multi-reaction-zone graphite furnace body is arranged in the reaction furnace chamber and comprises a first low-temperature zone, a second high-temperature zone and a third low-temperature zone which are sequentially arranged from bottom to top and are not in contact with one another; the electromagnetic heating controller is arranged on the periphery of the multi-reaction-area graphite furnace body; the graphite boat is movably arranged in the multi-reaction-area graphite furnace body; the movable alumina crucible is arranged in the graphite boat; the graphite columns are arranged at the top and the bottom of the multi-reaction-zone graphite furnace body; the hydraulic cylinder is connected with the graphite column; and a control assembly. Compared with the prior art, the method has the advantages that the nitridation reaction process can be accurately controlled, the fiber quality and the crystal integrity can be improved, and independent and accurate temperature control can be realized.

Description

Technical Field

[0001] This invention relates to the field of nitride calcination equipment technology, and in particular to a multi-flow alternating temperature calcination device for ultra-long nitride single-crystal nanofibers. Background Technology

[0002] Nitride ceramics are a new type of ceramic material that combines the advantages of ceramic materials, such as high temperature resistance, corrosion resistance, and wear resistance, with excellent thermal conductivity and electrical insulation, high-frequency dielectric constant, and low dielectric loss. They play a crucial role in electronic packaging, semiconductors, and extreme high-temperature thermal management, possessing extremely high application value and the potential to generate significant social and economic benefits. Nitride nanofibers, due to their nanometer diameter, exhibit significant surface and nanoscale effects, further expanding the application range of nitride ceramics.

[0003] Currently, nitride nanofibers can be obtained through carbothermal nitridation reduction, combustion, direct nitridation, and chemical vapor deposition. Among these methods, carbothermal reduction readily yields polycrystalline, hollow nitride nanofibers, but at the cost of the intrinsic mechanical and thermal conductivity properties of nitrides. Combustion directly uses nitride particles as raw materials for ultra-high temperature sublimation and recrystallization to prepare nitride whiskers, but the reaction is uncontrollable, and fibers appear as a byproduct of the particles. Direct nitridation and chemical vapor deposition involve nitriding a metal source after liquefaction and vaporization at high temperatures, followed by saturation, deposition, nucleation, and growth to form single-crystal nitride nanofibers. However, since the reaction zone of the existing calcination device is fixed and single (CN116538800A; CN114543523A), nitriding nucleation cannot occur at low temperatures; at ultra-high temperatures, the energy of each crystal facet of the nucleus is very large and the nucleation sites are in a highly active state, which leads to the random distribution of nitrides on each crystal facet during supersaturated deposition, which easily produces dendrites, tandem crystals, and other heteromorphic crystal structures, which also reduces the mechanical and thermal properties of nitride fibers. In addition, there are often a large amount of reactants left over, resulting in low fiber yield.

[0004] Therefore, there is an urgent need to develop a mobile calcination equipment with multiple reaction zones that can precisely control the nitriding reaction process, so as to nitrid most of the metal sources to construct high-yield, crystal-complete ultra-long nitride single-crystal nanofibers. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art by providing a multi-flow alternating temperature calcination device for ultra-long nitride single-crystal nanofibers, which can precisely control the nitriding reaction process, improve fiber quality and crystal integrity, and achieve independent and precise temperature control.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] This invention provides a multi-flow alternating temperature calcination apparatus for ultralong nitride single-crystal nanofibers, comprising:

[0008] Reactor;

[0009] A mechanical vacuum pressure gauge and an exhaust port are installed on the top of the reactor.

[0010] The reaction furnace cavity is located inside the reaction furnace;

[0011] The multi-reaction zone graphite furnace body is disposed inside the reaction furnace cavity. The multi-reaction zone graphite furnace body includes a first low-temperature zone, a second high-temperature zone and a third low-temperature zone arranged sequentially from bottom to top and not in contact with each other. The first low-temperature zone, the second high-temperature zone and the third low-temperature zone are respectively provided with an air inlet and an air outlet. The air inlet is located at the lower left of the corresponding zone and the air outlet is located at the upper right of the corresponding zone.

[0012] An electromagnetic heating controller is installed around the graphite furnace body in the multi-reaction zone.

[0013] A graphite boat that is movably disposed inside the graphite furnace body of the multi-reaction zone;

[0014] A movable alumina crucible disposed inside the graphite boat;

[0015] Graphite columns are disposed at the top and bottom of the graphite furnace body in the multi-reaction zone;

[0016] A hydraulic cylinder connected to the graphite column is used to drive the graphite boat to move between the reaction zones;

[0017] A cooling water inlet is located above the reactor; a cooling water outlet is located below the reactor.

[0018] The control component is connected to the exhaust port, hydraulic cylinder, cooling water outlet, air inlet, electromagnetic heating controller, and cooling water inlet for communication.

[0019] Furthermore, the reactor has a front-opening structure, and the opening direction can be left, right, up, or down, for placing the graphite boat directly above the lower graphite column.

[0020] Furthermore, a solenoid valve and a manual valve are installed at the outlet of the exhaust port; a solenoid valve and a manual valve are also installed at the cooling water inlet. The solenoid valves are three-way solenoid valves.

[0021] Furthermore, the reactor cavity is a quartz cavity, and multiple layers of graphite insulation felt are evenly placed inside the reactor cavity. These multiple layers of graphite insulation felt tightly wrap around the multi-reaction zone graphite furnace, with no gaps between them and the reactor cavity, and holes are left at the corresponding inlet and outlet positions. This serves both as insulation for the internal multi-reaction zone graphite furnace body and as thermal protection for the reactor cavity.

[0022] Furthermore, the first low-temperature zone is provided with a first low-temperature zone outlet and a first low-temperature zone inlet;

[0023] The second high-temperature zone is provided with a second high-temperature zone air outlet and a second high-temperature zone air inlet;

[0024] The third low-temperature zone is provided with a third low-temperature zone air outlet and a third low-temperature zone air inlet.

[0025] The first low-temperature zone air inlet, the second high-temperature zone air inlet, and the third low-temperature zone air inlet are all located outside the reactor cavity, penetrating the multi-reaction zone graphite furnace body, and connected to the inner wall of the multi-reaction zone graphite furnace body through pipes, with each air inlet maintaining the same height from the bottom surface of its respective zone.

[0026] Furthermore, the first low-temperature region is equipped with a first low-temperature region position detector, the second high-temperature region is equipped with a second high-temperature region position detector, and the third low-temperature region is equipped with a third low-temperature region position detector, for detecting the position of the graphite boat.

[0027] Furthermore, the electromagnetic heating controller includes: an infrared temperature monitor, infrared temperature monitoring points, and electromagnetic coils. It is used to accurately monitor and regulate the temperature of the multi-reaction zone graphite furnace body. The second high-temperature zone has more electromagnetic coils than the first and third low-temperature zones, thus providing a higher temperature.

[0028] The infrared temperature monitor is installed on the right side of the electromagnetic heating controller, close to the side wall of the multi-zone reaction graphite furnace.

[0029] The infrared temperature monitoring points are located at the upper left of each region of the multi-region graphite furnace body, 1 cm from the inner wall. They can accurately reflect the actual temperature inside the multi-region graphite furnace body, with a temperature deviation of ±5℃.

[0030] The electromagnetic coil is wound around the outer wall of each region of the multi-region reactive graphite furnace body, and its two ends are connected to the electromagnetic heating controller.

[0031] Furthermore, the graphite boat is initially positioned at the bottom of the multi-zone reaction graphite furnace, i.e., the first low-temperature zone. The graphite boat includes: a graphite boat inlet, a graphite boat outlet, a graphite cap, and a graphite felt. The bottom of the graphite boat has positioning graduations. It is aligned with the positioning graduations on the lower graphite column, ensuring that it is directly above the graphite column and aligned with the inlet and outlet of the multi-zone reaction graphite furnace.

[0032] The air inlet of the graphite boat is located at the lower left of the graphite boat, aligned with the air inlet of the first low-temperature region;

[0033] The gas outlet of the graphite boat is located at the upper right of the graphite boat, aligned with the gas outlet of the first low-temperature region;

[0034] The graphite cap is located above the graphite boat and fits the graphite boat perfectly.

[0035] The graphite felt is placed at the bottom and top of the graphite boat.

[0036] Furthermore, the graphite column includes a lower graphite column and an upper graphite column; the lower graphite column and the upper graphite column are placed symmetrically in the reactor cavity.

[0037] The lower graphite column is initially located at the bottom of the first low-temperature region and is in close contact with the lower part of the graphite boat during initial operation or operation.

[0038] The initial position of the upper graphite column is located at the top of the third low-temperature zone, and during operation, it is in close contact with the graphite cap of the graphite boat.

[0039] Only when the lower graphite column, the graphite boat, and the upper graphite column are tightly fitted together can the graphite boat be heated evenly.

[0040] Furthermore, the hydraulic cylinder includes a lower hydraulic cylinder and an upper hydraulic cylinder;

[0041] The lower hydraulic cylinder is located at the bottom of the reactor chamber and is in close contact with the lower graphite column;

[0042] The upper hydraulic cylinder is located at the top of the reactor chamber and is in close contact with the upper graphite column.

[0043] Furthermore, the control component will control the hydraulic cylinder motion structure through set parameters to control the movement area of ​​the graphite boat located on the hydraulic cylinder motion structure.

[0044] When the control component receives the motion zone command, it feeds back the signal to the hydraulic cylinder motion mechanism, the zone air inlet, the zone electromagnetic heating controller, the zone infrared monitor, and the zone cooling water control component. The upper hydraulic cylinder motion mechanism transports the graphite boat to the designated reaction zone, the zone air inlet solenoid valve opens to deliver the designated atmosphere, the zone electromagnetic heating controller adjusts to the required reaction temperature and adjusts it in real time according to the feedback from the zone infrared monitor, and the zone cooling water inlet solenoid valve opens and supplies / stops water according to the zone infrared monitoring.

[0045] This invention enables precise control of the nitridation reaction process of nitride single-crystal nanofibers, improves the length and crystal structure integrity of nitride nanofibers, and increases the yield of nitride single-crystal nanofibers.

[0046] The working principle is as follows:

[0047] Hydraulic cylinders and graphite columns are installed symmetrically at the top and bottom of the multi-reaction zone graphite furnace body and equipped with infrared emitters to propel the graphite boats to move freely within the multi-reaction zone graphite furnace body and determine their positions. The calcination process begins in the first low-temperature region, with the upper hydraulic cylinder / graphite column at its lowest maximum range and the lower hydraulic cylinder / graphite column at its lowest minimum range, where the metal source vaporizes without being nitrided. When the calcination process moves to the second high-temperature region, the upper and lower hydraulic cylinder / graphite column assemblies receive a motion command and move upwards. When the hydraulic cylinder / graphite column motion assembly reaches the second high-temperature region, the laser position receiver receives a laser signal from the motion assembly, and the hydraulic cylinder stops operating. At this point, the reaction chamber, the inlet and outlet ports of the graphite boat, and the infrared temperature monitoring point are aligned, the corresponding inlet ports begin to open, the electromagnetic coil in the reaction region begins to operate, the nitriding reaction begins, and nitride nucleation occurs. When the calcination process switches to the third low-temperature reaction zone, the hydraulic cylinder / graphite column assembly receives another command and moves upwards, where deposition and slow growth occur on the preferred growth crystal plane (the crystal plane with high crystal energy) at low temperature. Subsequently, it re-enters the second region, generates saturated vapor, and then returns to the third region for further growth. By repeating this process, the nitriding reaction process can be precisely controlled, and ultra-long, high-yield, and crystal-complete nitride single-crystal fibers can be obtained.

[0048] Compared with the prior art, the present invention has the following advantages:

[0049] (1) The nitriding reaction process can be precisely controlled. The multi-flow alternating temperature calcination device for ultra-long nitride single-crystal nanofibers of the present invention is equipped with a multi-reaction zone graphite furnace body, including a first low-temperature reaction zone, a second high-temperature reaction zone, and a third low-temperature reaction zone, which correspond to the metal source gasification zone, the nitriding reaction nucleation zone, and the deposition growth zone of the nitride fiber nitriding reaction, respectively. This makes the nitride raw material nitriding reaction process controllable and the reaction rate increased, thereby precisely controlling the growth of nitride single-crystal fibers. Three independent temperature zones (the first low-temperature zone, the second high-temperature zone, and the third low-temperature zone) are used to correspond to the metal source gasification zone, the nitriding reaction nucleation zone, and the deposition growth zone, respectively. The temperature zones do not contact each other. The reaction conditions of each zone are ensured to be independent by the uniform spacing of the quartz furnace body. The graphite boat driven by the hydraulic cylinder moves back and forth between the temperature zones to achieve precise control of the reaction process.

[0050] (2) Improve fiber quality and crystal integrity. By alternating high-temperature nucleation and low-temperature growth processes, nitrides are deposited on preferential growth crystal planes (crystal planes with high crystal energy), avoiding the formation of heterogeneous crystal structures such as dendrites, striations, and eccentric crystals. The multi-flow alternating temperature calcination device for ultralong nitride single-crystal nanofibers of the present invention is equipped with a hydraulic cylinder / graphite column moving assembly and a movable graphite boat. The reciprocating movement of the graphite boat between various reaction zones is automatically realized through the programmed extension and contraction of the upper and lower hydraulic cylinders, thereby improving the yield and crystal structure integrity of nitride fibers.

[0051] (3) Independent and precise temperature control can be achieved. The multi-flow alternating temperature calcination device for ultra-long nitride single-crystal nanofibers of the present invention has independently set air inlets and outlets, cooling water inlets, infrared temperature monitoring points, laser position detectors, and heating electromagnetic coils in each reaction zone, and the opening positions of each zone are consistent, so as to achieve independent control of reaction conditions and unified operation of each reaction zone. Each temperature zone adopts an independent electromagnetic heating controller and infrared temperature monitoring system; the second high temperature zone has more electromagnetic coils than the first and third low temperature zones, providing a higher temperature; the cooling water system can quickly adjust the temperature and maintain temperature balance. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the multi-flow alternating temperature calcination device for ultralong nitride single-crystal nanofibers in Example 1;

[0053] Figure 2 This is a schematic diagram of the structure of the multi-reaction zone graphite furnace body in Example 1;

[0054] Figure 3 This is a schematic diagram of the electromagnetic heating controller in Example 1;

[0055] Figure 4 This is a schematic diagram of the graphite boat dish in Example 1.

[0056] Attached reference numerals: 1. Reactor; 2. Mechanical vacuum pressure gauge; 3. Exhaust port; 4. Reactor cavity; 5. Multi-reaction zone graphite furnace body; 6. Electromagnetic heating controller; 7. Gas inlet; 8. Graphite boat; 9. Movable alumina crucible; 10. Graphite column; 11. Hydraulic cylinder; 12. Cooling water inlet; 13. Cooling water outlet; 5-1. First low-temperature zone; 5-2. Second high-temperature zone; 5-3. Third low-temperature zone; 5-4. Gas outlet of the first low-temperature zone; 5-5. Gas outlet of the second high-temperature zone. 5-6. Third low-temperature zone air outlet; 5-7. First low-temperature zone position detector; 5-8. Second high-temperature zone position detector; 5-9. Third low-temperature zone position detector; 6-1. Infrared temperature monitor; 6-2. Infrared temperature monitoring point; 6-3. Electromagnetic coil; 7-1. First low-temperature zone air inlet; 7-2. Second high-temperature zone air inlet; 7-3. Third low-temperature zone air inlet; 8-1. Graphite boat air inlet; 8-2. Graphite boat air outlet; 8-3. Graphite cover. Detailed Implementation

[0057] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, algorithms, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0058] Example 1

[0059] This embodiment provides a multi-flow alternating temperature calcination apparatus for ultralong nitride single-crystal nanofibers, such as... Figure 1-4 As shown, it includes:

[0060] Reactor 1;

[0061] A mechanical vacuum pressure gauge 2 and an exhaust port 3 are installed on the top of the reactor 1; the mechanical vacuum pressure gauge 2 is located on the top of the reactor 1; in this embodiment, the range of the mechanical vacuum pressure gauge 2 is -0.1 MPa to 0.3 MPa.

[0062] The reaction chamber 4 is located inside the reaction furnace 1;

[0063] A multi-reaction zone graphite furnace body 5 is disposed inside the reaction furnace cavity 4. The multi-reaction zone graphite furnace body 5 includes a first low-temperature zone 5-1, a second high-temperature zone 5-2, and a third low-temperature zone 5-3 arranged sequentially from bottom to top and not in contact with each other. The first low-temperature zone 5-1, the second high-temperature zone 5-2, and the third low-temperature zone 5-3 are respectively provided with an air inlet 7 and an air outlet. The air inlet 7 is located at the lower left of the corresponding zone, and the air outlet is located at the upper right of the corresponding zone. In this embodiment, the constant temperature range of the first low-temperature zone 5-1 is 800-1200℃, the constant temperature range of the second high-temperature zone 5-2 is 1200-2000℃, and the temperature range of the third low-temperature zone 5-3 is 200-800℃. In this embodiment, all temperature zones have the same spatial size and height of 20cm, with a 5cm interval between temperature zones. The air outlet is located 5cm from the top of the zone, and the air inlet 7 is located 5cm from the bottom of the zone, with an opening diameter of 1-2cm.

[0064] An electromagnetic heating controller 6 is installed around the graphite furnace body 5 in the multi-reaction zone;

[0065] A graphite boat 8 is movably disposed inside the graphite furnace body 5 of the multi-reaction zone;

[0066] The movable alumina crucible 9 is disposed inside the graphite boat 8;

[0067] Graphite columns 10 are disposed at the top and bottom of the graphite furnace body 5 in the multi-reaction zone;

[0068] The hydraulic cylinder 11 connected to the graphite column 10 is used to drive the graphite boat 8 to move between the reaction zones;

[0069] A cooling water inlet 12 is provided above the reactor 1; a cooling water outlet 13 is provided below the reactor 1;

[0070] The control component is communicatively connected to the exhaust port 3, hydraulic cylinder 11, cooling water outlet 13, air inlet 7, electromagnetic heating controller 6, and cooling water inlet 12.

[0071] In a specific embodiment, the reactor 1 has a front-opening door structure, which can open to the left, right, up, or down, for placing the graphite boat 8 directly above the lower graphite column 10. The solenoid valve is a three-way solenoid valve. In this embodiment, the door is switched on and off by a cylinder, a fixing plate, and a latch, which is a four-corner latch.

[0072] In a specific embodiment, a solenoid valve and a manual valve are installed at the outlet of the exhaust port 3. The solenoid valve is a straight-through type. When the gas pressure inside the reactor 1 exceeds 0.15 MPa, the solenoid valve at the exhaust port 3 automatically opens to exhaust gas, stabilizing it to 0–0.01 MPa. The inlet 7 is also equipped with a solenoid valve and a manual valve. The solenoid valve is a straight-through type, and the inlet gas type is an inert gas, such as one or more of argon, nitrogen, ammonia, helium, and carbon dioxide, with a gas flow rate of 0–10 L / min. The cooling water inlet 12 is also equipped with a solenoid valve and a manual valve. A filter screen is installed at the cooling water inlet 12 to prevent impurities in the water from entering the reactor 1. The cooling water assembly is activated when the equipment is turned on.

[0073] In this specific embodiment, the reactor chamber 4 is a quartz cavity, and multiple layers of graphite insulation felt are uniformly placed inside the reactor chamber 4. The multiple layers of graphite insulation felt tightly wrap around the multi-reaction zone graphite furnace 5, with no gaps between it and the reactor chamber 4, and holes are left at the corresponding inlet and outlet positions. This serves both as insulation for the internal multi-reaction zone graphite furnace body 5 and as thermal protection for the reactor chamber 4. In this embodiment, the thickness of the reactor chamber 4 is greater than 10cm, and the multiple layers of graphite insulation felt 4-1 are carbon fiber graphite felt, with a single layer thickness of 5cm, and can withstand 2000℃.

[0074] In a specific embodiment, the first low-temperature region 5-1 is provided with a first low-temperature region air outlet 5-4 and a first low-temperature region air inlet 7-1;

[0075] The second high-temperature zone 5-2 is provided with a second high-temperature zone air outlet 5-5 and a second high-temperature zone air inlet 7-2;

[0076] The third low-temperature zone 5-3 is provided with a third low-temperature zone air outlet 5-6 and a third low-temperature zone air inlet 7-3.

[0077] The first low-temperature zone air inlet 7-1, the second high-temperature zone air inlet 7-2, and the third low-temperature zone air inlet 7-3 are all located outside the reaction furnace cavity 4, penetrating the multi-reaction zone graphite furnace body 5, and connected to the inner wall of the multi-reaction zone graphite furnace body 5 through pipes, and the height of each air inlet from the bottom surface of the zone is consistent.

[0078] In a specific embodiment, the first low-temperature region 5-1 is provided with a first low-temperature region position detector 5-7, the second high-temperature region 5-2 is provided with a second high-temperature region position detector 5-8, and the third low-temperature region 5-3 is provided with a third low-temperature region position detector 5-9, for detecting the position of the graphite boat 8.

[0079] In a specific embodiment, the electromagnetic heating controller 6 includes: an infrared temperature monitor 6-1, an infrared temperature monitoring point 6-2, and an electromagnetic coil 6-3. It is used to accurately monitor and regulate the temperature of the multi-reaction zone graphite furnace body 5. The second high-temperature zone 5-2 has more electromagnetic coils 6-3 than the first low-temperature zone 5-1 and the third low-temperature zone 5-3, thus providing a higher temperature.

[0080] The infrared temperature monitor 6-1 is installed on the right side of the electromagnetic heating controller 6, close to the wall side of the multi-zone reaction graphite furnace body 5.

[0081] The infrared temperature monitoring point 6-2 is located at the upper left of each region of the multi-region reaction graphite furnace body 5, 1 cm away from the inner wall. It can accurately reflect the actual temperature inside the multi-region reaction graphite furnace body 5, with a temperature deviation of ±5℃.

[0082] The electromagnetic coil 6-3 is wound around the outer wall of each region of the multi-region reactive graphite furnace body 5, and its two ends are connected to the electromagnetic heating controller 6.

[0083] When a certain temperature zone requires heating, the electromagnetic heating controller 6 receives a command and activates the electromagnetic coil 6-3, generating a magnetic field around it. Under the influence of this magnetic field, molecules within the corresponding region of the multi-reaction zone graphite furnace body 5 undergo relative motion, causing the furnace body to spontaneously heat up and rapidly generate the required heat. The infrared temperature monitor 6-1 monitors the temperature. When the temperature exceeds the required level, the electromagnetic coil 6-3 reduces its power, and the corresponding cooling water inlet 12 opens to supply cooling water. This system automatically adjusts and records the power based on the temperature, maintaining temperature balance for a short period with a temperature difference not exceeding ±10℃.

[0084] In a specific embodiment, the graphite boat 8 is initially placed at the bottom of the multi-zone reaction graphite furnace body 5, i.e., the first low-temperature zone 5-1. The graphite boat 8 includes: a graphite boat inlet 8-1, a graphite boat outlet 8-2, a graphite cover 8-3, and a graphite felt. The bottom of the graphite boat 8 has positioning scales. It is placed aligned with the positioning scales on the lower graphite column 10, ensuring that it is directly above the graphite column 10 and aligned with the inlet and outlet of the multi-zone reaction graphite furnace body 5.

[0085] The graphite boat inlet 8-1 is located at the lower left of the graphite boat 8 and is aligned with the first low-temperature region inlet 7-1;

[0086] The gas outlet 8-2 of the graphite boat is located on the upper right of the graphite boat 8 and is aligned with the gas outlet 5-4 of the first low temperature region.

[0087] The diameter of the opening of the graphite boat vessel air inlet 8-1 and the graphite boat vessel air outlet 8-2 is 1-2cm; the graphite boat vessel air inlet 8-1 is 5cm away from the bottom of the graphite boat vessel 8, and the graphite boat vessel air outlet 8-2 is 5cm away from the top of the graphite boat vessel 8. The graphite boat vessel 8 can reciprocate in the multi-reaction zone graphite furnace body 5.

[0088] The graphite cap 8-3 is located above the graphite boat 8 and fits tightly with the graphite boat 8;

[0089] The graphite felt 8-4 is placed at the bottom and top of the graphite boat 8.

[0090] In a specific embodiment, the graphite column 10 includes a lower graphite column and an upper graphite column; the lower graphite column and the upper graphite column are placed symmetrically in the reactor chamber 4.

[0091] The lower graphite column is initially located at the bottom of the first low-temperature region 5-1, and is in close contact with the lower part of the graphite boat 8 during initial operation or operation.

[0092] The initial position of the upper graphite column is located at the top of the third low-temperature region 5-3, and during operation, it is in close contact with the graphite cap of the graphite boat 8.

[0093] Only when the lower graphite column, the graphite boat 8, and the upper graphite column are tightly fitted together can the graphite boat 8 be heated evenly.

[0094] In a specific embodiment, the hydraulic cylinder 11 includes a lower hydraulic cylinder and an upper hydraulic cylinder; in this embodiment, the maximum displacement of the hydraulic cylinder 11 is 50cm, the moving speed is 0.5~5cm / s (can be moved in jog or programmed), and the diameter of the pressure head is 15cm.

[0095] The lower hydraulic cylinder 11-1 is located at the bottom of the reactor chamber 4 and is in close contact with the lower graphite column;

[0096] The upper hydraulic cylinder 11-2 is located at the top of the reactor chamber 4 and is in close contact with the upper graphite column.

[0097] In a specific embodiment, the control component controls the moving structure of the hydraulic cylinder 11 through set parameters, thereby controlling the moving area of ​​the graphite boat 8 located on the moving structure of the hydraulic cylinder 11. In this embodiment, the control component includes a controller, which is a microcontroller or a processor based on x86, RISC-V, or ARM architectures.

[0098] When the control component receives the motion zone command, it feeds back the signal to the hydraulic cylinder 11 motion mechanism, the zone air inlet, the zone electromagnetic heating controller, the zone infrared monitor, and the zone cooling water control component. The upper hydraulic cylinder 11 motion mechanism transports the graphite boat 8 to the designated reaction zone. The zone air inlet solenoid valve opens to deliver the designated atmosphere. The zone electromagnetic heating controller is adjusted to the required reaction temperature and adjusted in real time according to the feedback from the zone infrared monitor. The zone cooling water inlet solenoid valve opens and supplies / stops water according to the zone infrared monitoring.

[0099] The multi-flow alternating temperature calcination apparatus for ultralong nitride single-crystal nanofibers in this embodiment is used for the preparation of aluminum nitride single-crystal nanofibers, including the following steps: restoring the reaction chamber from a vacuum state to an atmospheric pressure state and opening the furnace door; mixing aluminum particles, aluminum chloride particles, and iron powder and placing them in an alumina crucible, and placing it in the center of the graphite boat 8; placing the graphite felt and graphite boat 8 sequentially on the graphite column 10 of the lower hydraulic cylinder, aligning the scale lines and air inlet and outlet, covering the graphite boat cover 8-3 and the graphite felt, and opening the upper... The hydraulic cylinder is pressed tightly against the top layer of graphite felt, and the furnace door of the reactor is closed; the furnace is evacuated to a vacuum state, and the calcination program is set; the calcination program is started, and the graphite boat 8 reacts first in the first low temperature region 5-1, and then moves to the second high temperature region 5-2 and runs back and forth between the second high temperature region 5-2 and the third low temperature region 5-3, so as to achieve precise control of the nitride single crystal nanofiber nitridation reaction process, and obtain a large number of ultra-long aluminum nitride single crystal nanofibers with complete crystal structure and hexagonal wurtzite structure. During the calcination process, the cylinder moving speed is 3 cm / s. The first low-temperature zone 5-1 is 1000℃, calcined for 2 hours, with a heating rate of 10℃ / min, an argon atmosphere, and a gas flow rate of 0.6 L / min. The second high-temperature zone 5-2 is 1600℃, with a single calcination time of 10 min, a heating rate of 100℃ / min, a nitrogen atmosphere, and a gas flow rate of 0.4 L / min. The third low-temperature zone 5-3 is 600℃, with a single calcination time of 20 min, a heating rate of 5℃ / min, a nitrogen atmosphere, and a gas flow rate of 1 L / min. The second high-temperature zone 5-2 and the third low-temperature zone 5-3 alternate 15 times, with no temperature drop between them during the alternation. During cooling, the cooling rate of each zone is 20℃ / min.

[0100] This invention enables precise control of the nitridation reaction process of nitride single-crystal nanofibers, improves the length and crystal structure integrity of nitride nanofibers, and increases the yield of nitride single-crystal nanofibers.

[0101] Components not described in detail in this embodiment are all existing components that can be purchased through public channels.

[0102] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A multi-flow alternating temperature calcination apparatus for ultralong nitride single-crystal nanofibers, characterized in that, include: Reactor (1); A mechanical vacuum pressure gauge (2) and an exhaust port (3) are installed on the top of the reactor (1); The reactor chamber (4) is located inside the reactor (1); A multi-reaction zone graphite furnace body (5) is disposed inside the reaction furnace cavity (4). The multi-reaction zone graphite furnace body (5) includes a first low-temperature zone (5-1), a second high-temperature zone (5-2), and a third low-temperature zone (5-3) arranged sequentially from bottom to top and not in contact with each other. The first low-temperature zone (5-1), the second high-temperature zone (5-2), and the third low-temperature zone (5-3) are respectively provided with an air inlet (7) and an air outlet. Electromagnetic heating controller (6) is installed around the graphite furnace body (5) in the multi-reaction zone; A graphite boat (8) is movably disposed inside the graphite furnace body (5) of the multi-reaction zone; The movable alumina crucible (9) is disposed inside the graphite boat (8); Graphite columns (10) are disposed at the top and bottom of the multi-reaction zone graphite furnace body (5); A hydraulic cylinder (11) connected to the graphite column (10) is used to drive the graphite boat (8) to move between the reaction zones; A cooling water inlet (12) is provided above the reactor (1); a cooling water outlet (13) is provided below the reactor (1); The control component is connected to the exhaust port (3), hydraulic cylinder (11), cooling water outlet (13), air inlet (7), electromagnetic heating controller (6), and cooling water inlet (12) respectively.

2. The multi-flow alternating temperature calcination apparatus for ultralong nitride single-crystal nanofibers according to claim 1, characterized in that, The reactor (1) has a front-opening structure, and the opening direction can be left, right, up or down.

3. The multi-flow alternating temperature calcination apparatus for ultralong nitride single-crystal nanofibers according to claim 1, characterized in that, A solenoid valve and a manual valve are installed at the outlet of the exhaust port (3); a solenoid valve and a manual valve are also installed at the cooling water inlet (12).

4. The multi-flow alternating temperature calcination apparatus for ultralong nitride single-crystal nanofibers according to claim 1, characterized in that, The reaction furnace cavity (4) is a quartz cavity, and multiple layers of graphite insulation felt are evenly placed inside the reaction furnace cavity (4).

5. The multi-flow alternating temperature calcination apparatus for ultralong nitride single-crystal nanofibers according to claim 1, characterized in that, The first low-temperature zone (5-1) is provided with a first low-temperature zone outlet (5-4) and a first low-temperature zone inlet (7-1); The second high-temperature zone (5-2) is provided with a second high-temperature zone air outlet (5-5) and a second high-temperature zone air inlet (7-2); The third low-temperature zone (5-3) is provided with a third low-temperature zone air outlet (5-6) and a third low-temperature zone air inlet (7-3).

6. The multi-flow alternating temperature calcination apparatus for ultralong nitride single-crystal nanofibers according to claim 1, characterized in that, The first low-temperature region (5-1) is equipped with a first low-temperature region position detector (5-7), the second high-temperature region (5-2) is equipped with a second high-temperature region position detector (5-8), and the third low-temperature region (5-3) is equipped with a third low-temperature region position detector (5-9), which are used to detect the position of the graphite boat (8).

7. The multi-flow alternating temperature calcination apparatus for ultralong nitride single-crystal nanofibers according to claim 1, characterized in that, The electromagnetic heating controller (6) includes: an infrared temperature monitor (6-1), an infrared temperature monitoring point (6-2), and an electromagnetic coil (6-3).

8. The multi-flow alternating temperature calcination apparatus for ultralong nitride single-crystal nanofibers according to claim 1, characterized in that, The graphite boat (8) includes: a graphite boat air inlet (8-1), a graphite boat air outlet (8-2), a graphite cap (8-3), and a graphite felt; the bottom of the graphite boat (8) has positioning scales.

9. The multi-flow alternating temperature calcination apparatus for ultralong nitride single-crystal nanofibers according to claim 1, characterized in that, The graphite column (10) includes a lower graphite column and an upper graphite column; the lower graphite column and the upper graphite column are placed symmetrically in the reactor cavity (4).

10. The multi-flow alternating temperature calcination apparatus for ultralong nitride single-crystal nanofibers according to claim 1, characterized in that, The hydraulic cylinder (11) includes a lower hydraulic cylinder and an upper hydraulic cylinder; The lower hydraulic cylinder (11-1) is located at the bottom of the reactor chamber (4); The upper hydraulic cylinder (11-2) is located at the top of the reactor chamber (4).

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