Aluminum nitride nanofiber material production reaction furnace device

Abstract

The invention relates to a reaction furnace device for producing an aluminum nitride nanofiber material. The reaction furnace device comprises a heat transfer rod, a reaction furnace, a reaction kettle, a graphite crucible, an aluminum oxide boat, a graphite column and a hydraulic cylinder, the hydraulic air cylinder is used for pushing the graphite column, the single-layer movable crucible is pushed upwards to sequentially penetrate through the low-temperature area, the high-temperature area and the low-temperature area, and meanwhile different gases are introduced in a matched mode, so that directional and stable growth of nanofibers is achieved. Holes are formed in the side wall of the reaction kettle, and the positions of the holes are consistent with those of the holes in the side surface of the single-layer movable crucible, so that different airflows can be introduced into the three temperature zones. Compared with the prior art, the invention effectively solves the problems of insufficient crystal whisker growth length, disordered crystal lattices and the like caused by fixed crucible position, single gas and constant temperature in the existing reaction kettle, and the technology has important significance on continuous production of alumina nanofibers.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum nitride production equipment, in particular to a reactor device for producing aluminum nitride nanofiber materials. Background Art

[0002] Aluminum nitride materials have attracted much attention due to their outstanding physical and chemical properties, including high thermal conductivity, low dielectric constant, low dielectric loss, and excellent electrical insulation properties. In addition, the thermal expansion coefficient of aluminum nitride is similar to that of silicon, which gives it broad application prospects in the fields of refractory materials, ceramic substrates, and electronic packaging materials. The unique advantage of aluminum nitride nanofibers lies in their significant surface effects and nanoscale effects, which makes them of great value in the production of micro-wires and micro-fiber materials. At the same time, aluminum nitride nanofibers can also be used as reinforcing units in composite materials to effectively improve their thermodynamic properties. Therefore, in recent years, aluminum nitride nanofibers have received widespread attention from researchers.

[0003] Currently, the most commonly used method for preparing aluminum nitride nanofibers is the carbothermal reduction method. This method first synthesizes aluminum oxide nanofibers and then converts them into aluminum nitride nanofibers through a carbothermal reduction reaction. Another common preparation method is vapor deposition. This method can control the growth direction and position of aluminum nitride nanofibers by introducing nematic liquid crystals as templates or designing substrate materials with special morphologies, thereby achieving controllable growth of nanomaterials. In addition, by adjusting the catalyst conditions, gas flow rate, and its mixing ratio, a VS / VLS growth mode can be achieved, thereby obtaining nanofibers with specific morphologies. Some researchers have also prepared nanofibers by using self-made precursor materials, combining secondary growth, physical deposition, and chemical deposition. However, these preparation methods still face many challenges, such as thick and long fibers, poor morphology, diverse crystal forms, complex preparation processes, high costs, and difficulty in achieving large-scale continuous production. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a reactor device for producing aluminum nitride nanofiber materials, which solves the problems of insufficient fiber length, small aspect ratio and impure crystal form in the preparation process of aluminum nitride nanofibers in the prior art.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] The present invention provides a reactor device for producing aluminum nitride nanofiber materials, comprising: a heat transfer rod, a reactor, a graphite column and a hydraulic cylinder;

[0007] A reactor is provided in the reactor, and the top of the reactor is fixedly connected to the inner wall of the reactor top through a heat transfer rod, and a plurality of graphite felts are provided between the top of the reactor and the top of the reactor.

[0008] The reactor is equipped with a reaction kettle, a graphite boat and an alumina crucible;

[0009] The graphite boat is arranged in the reaction kettle, and the alumina crucible is arranged in the graphite boat;

[0010] The reactor is vertically provided with a low temperature zone, a high temperature zone, and a low temperature zone in sequence from bottom to top;

[0011] The hydraulic cylinder can lift the alumina crucible from bottom to top and displace it along the low-temperature zone, high-temperature zone, and low-temperature zone of the reactor, perform crystal precipitation and crystal nucleation in the low-temperature zone, realize crystal nucleus growth and whisker generation in the high-temperature zone, and finally complete the final sedimentation of the whiskers in the low-temperature zone.

[0012] Furthermore, the alumina crucible is used to hold sample raw materials and substrate materials;

[0013] The reactor has a diameter of 300 mm and a height of 600 mm.

[0014] Furthermore, the alumina crucible is a single-layer movable crucible, wherein a plurality of evenly distributed circular holes are provided on the side wall of the crucible for introducing airflow.

[0015] Furthermore, the diameter of the opening on the upper side wall of the single-layer movable crucible is 0.5 to 1 cm.

[0016] Furthermore, zone temperature adjustment is adopted. The temperature range of the first low-temperature zone from bottom to top in the vertical direction is set to 800-1000°C, the nucleation time of the aluminum nitride nanofiber material is 0.5-2h, the temperature range of the high-temperature zone is set to 1500-1800°C, the growth time of the aluminum nitride nanofiber material is 1-3h, and the temperature range of the second low-temperature zone is set to 600-800°C, and the deposition time of the aluminum nitride nanofiber material is 2-3h.

[0017] Furthermore, the single-layer movable crucible can be driven by a hydraulic cylinder to push the graphite column upward and lift it through the low-temperature zone, high-temperature zone and low-temperature zone of the reactor in sequence.

[0018] Furthermore, the side walls of the low-temperature zone and the high-temperature zone of the reactor are both provided with an open hole structure, and the open hole structure can be at the same height as the side wall open hole position of the alumina boat.

[0019] Furthermore, the temperature change process in the reactor is coordinated with multiple gas flows, which are one or more combinations of argon, helium, and carbon dioxide in the low temperature zone, and one or more combinations of nitrogen and ammonia in the high temperature zone.

[0020] Furthermore, the gas introduction rate is 1 to 5 L / min.

[0021] Furthermore, the reactor needs to be evacuated before ventilation and before the furnace is opened, and the vacuum degree range is -0.5 to -0.1 MPa.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The present invention precisely controls the growth morphology and orientation of aluminum nitride nanofibers by dividing the reactor into three temperature zones: a low-temperature zone, a high-temperature zone, and a low-temperature zone. The fiber growth process includes crystal precipitation and nucleation in the low-temperature zone, nucleation growth and whisker formation in the high-temperature zone, and final whisker sedimentation in the low-temperature zone.

[0024] (2) The present invention introduces a highly inert gas as a protective gas in the low-temperature zone and introduces nitrogen and other reactive gases into the high-temperature zone. By regulating multiple gas flows, the controllable synthesis of aluminum nitride nanofibers is achieved.

[0025] (3) The present invention utilizes a movable single-layer graphite crucible, which, under the action of a hydraulic cylinder, pushes the graphite column through the low-temperature zone, the high-temperature zone, and the low-temperature zone in sequence. The sidewall of the graphite crucible is provided with an opening structure, which is consistent with the position and height of the openings in each temperature zone, thereby ensuring that the corresponding atmosphere is introduced into each temperature zone and effectively preventing airflow mixing. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the overall structure of a reactor for producing aluminum nitride nanofiber materials according to the present invention;

[0027] Numbers in the figure: 1. Mechanical vacuum gauge; 2. Furnace top air inlet; 3. Heat transfer rod; 4. Reactor; 5. Reactor; 6. Cooling water discharge port; 7. Graphite crucible; 8. Alumina crucible; 9. Reaction substrate material; 10. Graphite column; 11. Hydraulic cylinder. DETAILED DESCRIPTION

[0028] The technical problem to be solved by the present invention is that due to insufficient preparation conditions, the growth direction of aluminum nitride nanofibers is difficult to control, the growth length is insufficient, and the lattice is disordered.

[0029] The present synthesis method utilizes a variable temperature, multi-flow process. The variable temperature section of the reactor utilizes the principles of a three-zone tubular furnace, with a staggered arrangement of low-temperature, high-temperature, and low-temperature zones from bottom to top. Each zone is controlled by a separate heating element, and three infrared thermometers are used to display the temperature in real time. Holes are drilled into the sidewalls of the graphite crucible, matching the height and size of the holes in the reactor's temperature zones. A hydraulic cylinder propels the graphite column upward, ensuring the introduction of the specified atmosphere into each temperature zone.

[0030] In general, the purpose of the present invention is to provide a reactor for producing aluminum nitride nanofiber materials, which includes a heat transfer rod, a reactor, a graphite column and a hydraulic cylinder.

[0031] In one embodiment of the present invention, the reactor has a diameter of 300 mm and a height of 600 mm.

[0032] A reactor is provided in the reactor, and the top of the reactor is fixedly connected to the inner wall of the reactor top through a heat transfer rod. A plurality of graphite felts are included between the top of the reactor and the top of the reactor to effectively prevent heat loss.

[0033] The reactor comprises a reaction kettle, a graphite boat and an alumina crucible, wherein the graphite boat is used to hold containers and raw materials, and the alumina crucible is used to hold sample raw materials and reaction substrate materials. The reaction substrate materials have vertically arranged pores of different shapes, which are prepared by freeze-drying.

[0034] The alumina crucible is a single-layer movable crucible, wherein the side wall of the crucible has evenly distributed circular holes for introducing air flow.

[0035] In one embodiment of the present invention, the diameter of the circular hole on the side wall of the crucible is 0.5 to 1 cm.

[0036] The single-layer movable crucible is driven by a hydraulic cylinder, and the graphite column pushes the crucible upward, passing through the low-temperature zone, high-temperature zone and low-temperature zone of the reactor in sequence.

[0037] In an embodiment of the present invention, the reactor is configured to have a low-temperature zone, a high-temperature zone, and a low-temperature zone arranged alternately, and adopts zone temperature adjustment. The temperature range of the first low-temperature zone is set to 800-1000°C, the nucleation time is 0.5-2h, the temperature range of the high-temperature zone is set to 1500-1800°C, the growth time is 1-3h, and the temperature range of the second low-temperature zone is set to 600-800°C, and the deposition time is 2-3h.

[0038] The side walls of the low-temperature zone and the high-temperature zone of the reactor are both provided with an opening structure, and the opening position of the side wall of the alumina boat is at the same height to ensure the flow of air into each temperature zone and avoid mixing of gases between the zones;

[0039] In one embodiment of the present invention, the temperature-changing process in the reactor is combined with multiple gas flows, which are one or more combinations of argon, helium, and carbon dioxide in the low-temperature zone and one or more combinations of nitrogen and ammonia in the high-temperature zone.

[0040] In one embodiment of the present invention, the gas is introduced at a rate of 1 to 5 L / min.

[0041] In one embodiment of the present invention, the reactor needs to be vacuumed before ventilation and before the furnace is opened, and the vacuum degree range is -0.5 to -0.1 MPa.

[0042] The growth mechanism of the present invention is as follows: when the gaseous reactants reach saturated vapor pressure, crystals precipitate and form crystal nuclei. The crystal nuclei grow in a directionally controlled manner under the action of aluminum nitride vapor, and ultimately generate whiskers. The aluminum nitride nanofiber material is prepared using the gas-solid growth mechanism. During the whisker formation process, due to the difference in the crystal face energy of different crystal faces, the crystal faces with larger crystal face energy have a stronger attraction to gaseous molecules. Therefore, the aluminum nitride vapor preferentially deposits on the crystal faces with larger crystal face energy. This causes the growth rate of the crystal faces with larger crystal face energy to be significantly faster than that of the crystal faces with smaller crystal face energy, ultimately forming whiskers with a certain aspect ratio. In addition, the supersaturation of the aluminum nitride vapor plays an important role in the nucleation and growth of the crystals. When the supersaturation of the aluminum nitride vapor in the reaction system is low, crystal nuclei cannot form; if the supersaturation of the aluminum nitride vapor is too high, the whiskers will become coarse, and even aluminum nitride dendrites will be generated. Only when the supersaturation reaches a certain level can the crystal nuclei be generated and continue to grow into whiskers.

[0043] The present invention will be described in detail below 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.

[0044] Example 1

[0045] This embodiment provides a reactor for producing aluminum nitride nanofiber materials. Figure 1 , including a mechanical vacuum gauge, a furnace top air inlet, a heat transfer rod 3, a reaction furnace 4, a graphite column 10 and a hydraulic cylinder 11, a cooling water outlet and a furnace bottom air inlet.

[0046] In a specific implementation, a reactor 5 is provided in the reactor 4, and the top of the reactor 5 is fixedly connected to the inner wall of the top of the reactor 4 through a heat transfer rod 3, and a plurality of graphite felts are contained between the top of the reactor 4 and the top of the reactor 5;

[0047] In specific implementation, the diameter of the reaction furnace 4 is 300 mm and the height is 600 mm;

[0048] In a specific implementation, the reaction furnace 4 includes a reaction kettle 5, a graphite boat 7 and an alumina crucible 8, wherein the graphite boat 7 is used to hold containers and raw materials, and the alumina crucible 8 is used to hold sample raw materials and substrate materials 9;

[0049] In a specific implementation, the alumina crucible 8 is a single-layer movable crucible, wherein the side wall of the crucible has evenly distributed circular holes to introduce airflow;

[0050] In a specific implementation, the diameter of the opening on the side wall of the single-layer movable crucible is 0.5 cm;

[0051] In specific implementation, the single-layer movable crucible is driven by the hydraulic cylinder 11 to push the graphite column 10 upward and lift it, passing through the low temperature zone, high temperature zone and low temperature zone of the reactor in sequence;

[0052] In specific implementation, the reactor is set to a staggered arrangement of low-temperature zone, high-temperature zone, and low-temperature zone, and adopts zone temperature adjustment. The temperature range of the first low-temperature zone is set to 800°C, the nucleation time is 1 hour, the temperature range of the high-temperature zone is set to 1600°C, the growth time is 2 hours, and the temperature range of the second low-temperature zone is set to 600°C, and the deposition time is 3 hours.

[0053] In specific implementation, the side walls of the low temperature zone and the high temperature zone of the reactor are both provided with an opening structure, and the opening position of the side wall of the alumina boat is at the same height;

[0054] In specific implementation, the temperature change process in the reactor 5 is combined with multiple gas flows, argon is introduced in the low temperature zone, and nitrogen is introduced in the high temperature zone;

[0055] In specific implementation, the gas introduction rate is 1 to 5 L / min;

[0056] In specific implementation, the reactor needs to be evacuated before ventilation and before the furnace is opened, and the vacuum degree range is -0.5 to -0.1 MPa.

[0057] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. 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 present invention, should be within the scope of protection of the present invention.

Claims

1. A reactor device for producing aluminum nitride nanofiber material, characterized in that: include: It comprises a heat transfer rod (3), a reaction furnace (4), a graphite column (10) and a hydraulic cylinder (11); A reaction kettle (5) is arranged in the reaction furnace (4), and the top of the reaction kettle (5) is fixedly connected to the inner wall of the top of the reaction furnace (4) through a heat transfer rod (3), and a plurality of graphite felts are arranged between the top of the reaction furnace (4) and the top of the reaction kettle (5); The reaction furnace (4) is provided with a reaction kettle (5), a graphite boat (7), and an alumina crucible (8); The graphite boat (7) is arranged in the reaction kettle (5), the graphite boat (7) is arranged in the reaction kettle (5), and the alumina crucible (8) is arranged in the graphite boat (7); The reaction kettle (5) is provided with a low temperature zone, a high temperature zone, and a low temperature zone in sequence from bottom to top in the vertical direction; The hydraulic cylinder (11) can lift the alumina crucible (8) from bottom to top and displace it along the low temperature zone, high temperature zone, and low temperature zone of the reaction kettle (5), perform crystal precipitation and crystal nucleus formation in the low temperature zone, achieve crystal nucleus growth and whisker generation in the high temperature zone, and finally complete the final sedimentation of the whiskers in the low temperature zone.

2. The aluminum nitride nanofiber material production reactor device according to claim 1, characterized in that: The alumina crucible (8) is used to hold sample raw materials and substrate materials (9); The reaction furnace (4) has a diameter of 300 mm and a height of 600 mm.

3. The aluminum nitride nanofiber material production reactor device according to claim 1, characterized in that: The alumina crucible (8) is a single-layer movable crucible, wherein a plurality of evenly distributed circular holes are provided on the side wall of the crucible for introducing airflow.

4. The aluminum nitride nanofiber material production reactor device according to claim 3, characterized in that: The diameter of the opening on the upper side wall of the single-layer movable crucible is 0.5-1 cm.

5. The aluminum nitride nanofiber material production reactor device according to claim 3, characterized in that: And zone temperature control is adopted. The temperature range of the first low-temperature zone from bottom to top in the vertical direction is set to 800-1000°C, the nucleation time of the aluminum nitride nanofiber material is 0.5-2h, the temperature range of the high-temperature zone is set to 1500-1800°C, the growth time of the aluminum nitride nanofiber material is 1-3h, the temperature range of the second low-temperature zone is set to 600-800°C, and the deposition time of the aluminum nitride nanofiber material is 2-3h.

6. The aluminum nitride nanofiber material production reactor device according to claim 3, characterized in that: The single-layer movable crucible can drive the graphite column (10) to be pushed and lifted upwards by the hydraulic cylinder (11), and sequentially passes through the low-temperature zone, the high-temperature zone and the low-temperature zone of the reaction kettle.

7. The aluminum nitride nanofiber material production reactor device according to claim 5, characterized in that: The side walls of the low temperature zone and the high temperature zone of the reaction kettle (5) are both provided with an open hole structure, and the open hole structure can be at the same height as the side wall open hole position of the alumina boat (7).

8. The aluminum nitride nanofiber material production reactor device according to claim 3, characterized in that: The temperature change process in the reactor (5) is coordinated with multiple gas flows, which are one or more combinations of argon, helium and carbon dioxide in the low temperature zone, and one or more combinations of nitrogen and ammonia in the high temperature zone.

9. The aluminum nitride nanofiber material production reactor device according to claim 8, characterized in that: The gas introduction rate is 1 to 5 L / min.

10. The aluminum nitride nanofiber material production reactor device according to claim 8, characterized in that: The reactor (5) needs to be evacuated before ventilation and before the furnace is turned on, and the vacuum degree range is -0.5 to -0.1 MPa.

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