Device and method for preparing boron nitride nanotube by using direct-current plasma

Abstract

The invention discloses a device and a method for preparing a boron nitride nanotube by using direct current plasma, and relates to the technical field of nano materials, the device comprises a gas supply cylinder group, the gas supply cylinder group is communicated with a master control terminal, the master control terminal can convey reaction gas to a plasma spray gun, a powder feeding module can convey a boron-containing raw material to the plasma spray gun, and the plasma spray gun is communicated with the powder feeding module; the plasma spray gun can generate direct-current plasmas, boron-containing raw materials and reaction gas are mixed and react to form boron nitride nanotubes, the output end of the plasma spray gun is communicated with the water-cooling cavity, and the boron nitride nanotubes formed through the reaction are discharged into the water-cooling cavity and cooled in the water-cooling cavity. The direct current is utilized to generate plasma, the plasma is combined with the boron-containing raw material and the reaction gas to prepare the boron nitride nanotube with high quality, the water cooling cavity can effectively cool the boron nitride nanotube, the stability of the boron nitride nanotube in the synthesis process and the quality of a final product are ensured, and the structures are matched for use to realize large-scale preparation of the boron nitride nanotube.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterials, and in particular to a device and method for preparing boron nitride nanotubes by utilizing direct current plasma. Background Art

[0002] Boron nitride nanotubes (BNNTs) are a nanomaterial with unique properties. Their thermal conductivity rivals that of carbon nanotubes, and they possess excellent insulation and thermal stability. They are used in sensors, high-temperature composites, high-strength fibers, and ceramic composites. Furthermore, BNNTs possess excellent piezoelectric properties, biocompatibility, and hydrogen storage capabilities, leading to their widespread application in aerospace, hydrogen storage materials, and biomedicine.

[0003] BNNTs can be synthesized using a variety of methods, including arc discharge, laser ablation, mechanical ball milling, carbon nanotube replacement, and chemical vapor deposition (CVD). Arc discharge, the earliest method used to prepare BNNTs, uses refractory metals and metal borides as electrodes to generate BNNTs through discharge in a specific atmosphere. Laser ablation uses a laser to bombard boron-containing compounds in a high-pressure gas atmosphere, generating BNNTs through a high-temperature reaction. Mechanical ball milling is a low-temperature method that produces BNNTs by milling boron powder and then annealing it in a high-temperature nitrogen atmosphere. The carbon nanotube replacement method, based on the similar structure of BNNTs and carbon nanotubes (CNTs), chemically replaces carbon atoms in CNTs with boron and nitrogen atoms to produce BNNTs. Chemical vapor deposition is a promising method for the large-scale synthesis of BNNTs, producing BNNTs through a chemical reaction between gaseous reactants and solid reactants.

[0004] The above synthesis methods generally have the following problems: when ensuring product quality, the single preparation yield is low and it is not easy to prepare in large quantities; when preparing in large quantities, the product quality is low and it is not easy to prepare high-quality boron nitride nanotubes.

[0005] In view of this, how to provide a high-quality, high-yield BNNTs synthesis device and method is a problem that technical personnel in this field urgently need to solve. Summary of the Invention

[0006] The purpose of the present invention is to provide a device and method for preparing boron nitride nanotubes using direct current plasma, so as to solve the problems existing in the prior art.

[0007] To achieve the above object, the present invention provides the following solution: The present invention provides a device for preparing boron nitride nanotubes using DC plasma, comprising:

[0008] A gas supply cylinder group, wherein the gas supply cylinder group is connected to the master control terminal;

[0009] Plasma spray gun, the gas supply cylinder group can deliver multiple reaction gases to the master control terminal, and the master control terminal can deliver one reaction gas or a mixture of multiple reaction gases to the plasma spray gun;

[0010] a powder feeding module, the powder feeding module being capable of feeding boron-containing raw materials to the plasma spray gun;

[0011] The plasma spray gun is capable of generating direct current plasma and mixing the boron-containing raw material with the reaction gas to react and form boron nitride nanotubes. The output end of the plasma spray gun is connected to the water-cooling cavity. The boron nitride nanotubes formed by the reaction are discharged into the water-cooling cavity and cooled in the water-cooling cavity.

[0012] Furthermore, the gas supply cylinder group delivers nitrogen-containing gas, hydrogen-containing gas and arc starting gas to the master control terminal.

[0013] Preferably, the gas supply cylinder group delivers nitrogen, argon, and ammonia to the master control terminal, wherein argon is the arc starting gas. The flow rate of the nitrogen is 1-200 L / min, the flow rate of the argon is 20-500 L / min, and the flow rate of the ammonia is 1-200 L / min.

[0014] Furthermore, it also includes:

[0015] A transfer box electrically connected to the plasma power supply;

[0016] A water chiller, the water-cooling cavity has a water inlet and a water outlet, the water chiller is respectively connected to the adapter box and the water inlet of the water-cooling cavity; the adapter box can integrate the direct current generated by the plasma power supply with the cooling water transported by the water chiller to form a charged water flow, and the adapter box transports the charged water flow to the plasma spray gun through a water cable.

[0017] Furthermore, the powder feeding module includes a powder feeding gas cylinder and a powder feeder, the powder feeding gas cylinder and the powder feeder are connected, and the powder feeder is connected to the plasma spray gun through a powder feeding pipe.

[0018] Furthermore, the water-cooling cavity includes an upper cooling cavity and a lower cooling cavity that are connected in one piece, the upper cooling cavity is connected to the output end of the plasma spray gun, the lower cooling cavity has a sliding feeding door, and the upper cooling cavity and the lower cooling cavity are both provided with a water inlet and a water outlet.

[0019] Furthermore, it also includes an exhaust gas treatment module, which includes an exhaust pipe and an exhaust gas treatment device. One end of the exhaust pipe is connected to the lower cooling cavity, and the other end is connected to the exhaust gas treatment device. The exhaust pipe is provided with a safety valve and a pressure gauge.

[0020] The present invention also provides a method for preparing boron nitride nanotubes using direct current plasma, comprising the following steps:

[0021] S1: Cooling the water-cooling cavity with cooling water:

[0022] S2: Control the plasma spray gun to generate DC plasma;

[0023] S3: feeding boron-containing raw materials and reaction gases into a plasma spray gun to prepare boron nitride nanotubes;

[0024] S4: Boron nitride nanotubes are sent into a water-cooling chamber through a plasma spray gun for cooling.

[0025] The present invention discloses the following technical effects:

[0026] 1. This invention utilizes direct current (DC) to generate plasma, combined with boron-containing raw materials and reaction gases, to produce high-quality boron nitride nanotubes. A water-cooled chamber effectively cools the boron nitride nanotubes, ensuring their stability during the synthesis process and the quality of the final product. The use of DC plasma significantly reduces overall equipment costs. The coordinated use of a plasma spray gun, gas supply cylinder assembly, powder feeding module, water-cooled chamber, and master control terminal enables large-scale production of boron nitride nanotubes.

[0027] 2. The present invention specifically defines the components and flow rates of the reaction gases. Nitrogen-containing gas, hydrogen-containing gas, and arc-ignition gas are delivered to the plasma spray gun via a gas supply cylinder assembly and a master control terminal. This allows for precise control of the flow rates and ratios of the reaction gases, thereby improving the synthesis efficiency and quality of boron nitride nanotubes.

[0028] 3. The adapter box integrates the direct current generated by the plasma power supply with the cooling water delivered by the chiller to form a charged water flow, and transmits it to the plasma spray gun through a water cable. This design not only improves the stability of the plasma, but also enhances the controllability of the reaction.

[0029] 4. The tail gas treatment module includes a tail gas pipe and a tail gas treatment device, which can effectively treat the tail gas generated during the reaction process and ensure the safe operation of the system through a safety valve and a pressure gauge. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 This is a structural layout diagram of the present invention;

[0032] Figure 2 This is a microscopic diagram of the boron nitride nanotubes prepared in Example 1;

[0033] Among them, 1. Gas supply cylinder group; 2. Master control terminal; 3. Plasma power supply; 4. Adapter box; 5. Chiller; 6. Powder feeding cylinder; 7. Powder feeder; 8. Plasma spray gun; 9. Upper cooling chamber; 10. Lower cooling chamber; 11. Safety valve; 12. Pressure gauge; 13. Exhaust gas treatment device. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] Example 1

[0037] An embodiment of the present invention provides an apparatus for preparing boron nitride nanotubes using direct current plasma, comprising: a gas supply cylinder group 1, the gas supply cylinder group 1 being connected to a master control terminal 2; a plasma spray gun 8, the gas supply cylinder group 1 being capable of delivering a plurality of reaction gases to the master control terminal 2, and the master control terminal 2 being capable of delivering a single reaction gas or a mixture of a plurality of reaction gases to the plasma spray gun 8; a powder feeding module, the powder feeding module being capable of delivering a boron-containing raw material to the plasma spray gun 8; and a water-cooling cavity, the plasma spray gun 8 being capable of generating direct current plasma and reacting a mixture of the boron-containing raw material and the reaction gas to form boron nitride nanotubes, the output end of the plasma spray gun 8 being connected to the water-cooling cavity, and the boron nitride nanotubes formed by the reaction being discharged into the water-cooling cavity and cooled therein.

[0038] The gas supply cylinder group 1 delivers nitrogen-containing gas, hydrogen-containing gas, and arc-starting gas to the master control terminal 2. The nitrogen-containing gas can be nitrogen or other nitrogen-containing gases, and the hydrogen-containing gas can be other hydrogen-containing gases such as ammonia and hydrogen. In this embodiment, the gas supply cylinder group 1 delivers nitrogen, argon, and ammonia to the master control terminal 2, wherein argon is the arc-starting gas. The flow rate of nitrogen is 100 L / min, the flow rate of argon is 260 L / min, and the flow rate of ammonia is 100 L / min. Argon is used for arc starting and maintaining plasma generation, nitrogen is used to provide a nitrogen source, and ammonia is used as a catalyst. The plasma spray gun 8 uses pure argon for arc starting. When the DC plasma is stable, the flow rates of the three gases are adjusted to achieve the above parameters.

[0039] This embodiment further includes: an adapter box 4 electrically connected to the plasma power supply 3; a water chiller 5; a water-cooled chamber having a water inlet and a water outlet, the water chiller 5 being connected to the adapter box 4 and the water inlet of the water-cooled chamber, respectively; the adapter box 4 is capable of integrating the direct current generated by the plasma power supply 3 with the cooling water delivered by the water chiller 5 to form a charged water flow, which is then delivered to the plasma spray gun 8 via a water cable. The water pressure of the water chiller 5 is 0.2-1 MPa, preferably 0.6 MPa in this embodiment.

[0040] In the present embodiment, the powder feeding module includes a powder feeding gas cylinder 6 and a powder feeder 7, the powder feeding gas cylinder 6 and the powder feeder 7 are connected, and the powder feeder 7 is connected to the plasma spray gun 8 through a powder feeding pipe. Boron-containing raw materials include but are not limited to boron powder, ammonia borane, etc., and also include other boron-containing substances. Boron powder is preferably used in this embodiment. The powder feeder 7 uses gas transportation to feed the boron-containing raw material into the plasma spray gun 8. The powder feeding amount of the powder feeder 7 is 5-100g / min, and the carrier gas flow rate is 5-50L / min. The preferred powder feeding amount in this embodiment is 50g / min, and the carrier gas flow rate is 30L / min.

[0041] The plasma spray gun 8 is respectively provided with a water cable inlet, a water cable outlet (output end), a gas inlet and an internal powder feeding inlet. The water cable inlet is connected to the water cable, the water cable outlet is connected to the water-cooled chamber, the gas inlet is connected to the master control terminal 2, and the internal powder feeding inlet is connected to the powder feeding pipeline. In addition to being used to control the flow and proportion of the reaction gas, the master control terminal 2 is also connected to the adapter box 4, the chiller 5 and the powder feeder 7 respectively to control the start and stop of each device and the flow of boron-containing raw materials and cold water. In addition to having the function of water and electricity integration, the adapter box 4 is also responsible for the arc starting of the plasma spray gun 8. The plasma temperature generated by the plasma spray gun 8 is 3000-12000°C, and the preferred temperature in this embodiment is 7500°C.

[0042] In this embodiment, the water-cooling chamber includes an upper cooling chamber 9 and a lower cooling chamber 10, which are integrally connected. The upper cooling chamber 9 is connected to the output of the plasma spray gun 8, while the lower cooling chamber 10 has a sliding access door. This sliding access door ensures a sealed function during the preparation of boron nitride nanotubes, preventing air and water leakage. Both the upper cooling chamber 9 and the lower cooling chamber 10 are equipped with a water inlet and outlet.

[0043] In this embodiment, an exhaust gas treatment module is also included, which includes an exhaust pipe and an exhaust gas treatment device 13. One end of the exhaust pipe is connected to the lower cooling cavity 10, and the other end is connected to the exhaust gas treatment device 13. A safety valve 11 and a pressure gauge 12 are provided on the exhaust pipe.

[0044] The method for preparing boron nitride nanotubes is described in detail below in conjunction with the above embodiments, including the following steps:

[0045] S1: Start the control terminal to control the chiller 5 to start and cool the water-cooled cavity with cooling water:

[0046] S2: Control the plasma spray gun 8 to generate DC plasma and simultaneously supply pure argon gas to the plasma spray gun 8. When the DC plasma is stable, nitrogen, argon and ammonia are supplied to the plasma spray gun 8 according to a preset ratio and flow rate;

[0047] S3: boron powder is fed to the plasma spray gun 8. Under the high temperature of the plasma, the boron powder reacts with the reaction gas to form boron nitride nanotubes.

[0048] S4: The boron nitride nanotubes are fed into the water cooling chamber through the plasma spray gun 8 for cooling. The sliding material taking door of the lower cooling chamber 10 is opened to take out the boron nitride nanotubes.

[0049] The boron nitride nanotubes prepared in this embodiment are as follows Figure 2 As shown, it should be noted that the quality of boron nitride nanotubes is reflected in the diameter (the smaller the better) and the number of tube walls (the fewer the number of tube walls, the better). The boron nitride nanotubes prepared in this embodiment have mostly single-layer walls, and a small amount have multi-layer walls (about 3 layers). The diameter is about 10 nm, and the yield is about 40 g / h.

[0050] Example 2

[0051] This example differs from Example 1 in that the nitrogen flow rate is 1 L / min, the argon flow rate is 20 L / min, and the ammonia flow rate is 1 L / min. The tube wall is mostly single-layer, with a small amount having multilayer walls (approximately 3 layers). The diameter is approximately 10 nm, and the yield is approximately 20 g / min.

[0052] Example 3

[0053] The difference between this embodiment and embodiment 1 is that the flow rate of nitrogen is 200 L / min, the flow rate of argon is 500 L / min, the flow rate of ammonia is 200 L / min, the tube wall is mostly single-layer, and a small amount is multi-layer tube wall (about 3 layers), the diameter is about 10 nm, and the yield is about 100 g / min.

[0054] Example 4

[0055] This example differs from Example 1 in that nitrogen gas is used at 10 L / min, argon at 30 L / min, and ammonia at 5 L / min. The tube walls are mostly single-layer, with a small amount having multilayer walls (approximately three layers). The diameter is approximately 10 nm, and the yield is 50 g / min. Compared to Example 3, Example 3 has a higher yield, but requires a higher plasma power supply. Example 4 requires a lower power supply. At the same power, Example 4 has a higher yield than Example 3, making it the optimal example.

[0056] In the description of the present invention, it should be understood that the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0057] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A device for preparing boron nitride nanotubes using direct current plasma, characterized in that: include: A gas supply cylinder group (1), wherein the gas supply cylinder group (1) is connected to a master control terminal (2); A plasma spray gun (8), wherein the gas supply cylinder group (1) is capable of delivering a plurality of reaction gases to the master control terminal (2), and the master control terminal (2) is capable of delivering a single reaction gas or a mixture of a plurality of reaction gases to the plasma spray gun (8); a powder feeding module, the powder feeding module being capable of feeding boron-containing raw materials to the plasma spray gun (8); The plasma spray gun (8) is capable of generating direct current plasma and mixing the boron-containing raw material with the reaction gas to form boron nitride nanotubes. The output end of the plasma spray gun (8) is connected to the water-cooling cavity, and the boron nitride nanotubes formed by the reaction are discharged into the water-cooling cavity and cooled in the water-cooling cavity.

2. The device for preparing boron nitride nanotubes using direct current plasma according to claim 1, characterized in that: The gas supply cylinder group (1) delivers nitrogen-containing gas, hydrogen-containing gas and arc-starting gas to the master control terminal (2).

3. The device for preparing boron nitride nanotubes using direct current plasma according to claim 2, characterized in that: The gas supply cylinder group (1) delivers nitrogen, argon and ammonia to the master control terminal (2), wherein argon is the arc starting gas.

4. The device for preparing boron nitride nanotubes using direct current plasma according to claim 3, characterized in that: The flow rate of the nitrogen gas is 1-200 L / min, the flow rate of the argon gas is 20-500 L / min, and the flow rate of the ammonia gas is 1-200 L / min.

5. The device for preparing boron nitride nanotubes using direct current plasma according to claim 1, characterized in that: Also includes: A transfer box (4), wherein the transfer box (4) is electrically connected to the plasma power supply (3); A water chiller (5), the water-cooling cavity having a water inlet and a water outlet, the water chiller (5) being connected to the adapter box (4) and the water inlet of the water-cooling cavity respectively; the adapter box (4) being capable of integrating the direct current generated by the plasma power supply (3) with the cooling water delivered by the water chiller (5) to form a charged water flow, and the adapter box (4) delivering the charged water flow to the plasma spray gun (8) via a water cable.

6. The device for preparing boron nitride nanotubes using direct current plasma according to claim 1, characterized in that: The powder feeding module comprises a powder feeding gas cylinder (6) and a powder feeder (7), the powder feeding gas cylinder (6) and the powder feeder (7) are in communication, and the powder feeder (7) is in communication with the plasma spray gun (8) via a powder feeding pipeline.

7. The device for preparing boron nitride nanotubes using direct current plasma according to claim 1, characterized in that: The water-cooling cavity comprises an upper cooling cavity (9) and a lower cooling cavity (10) which are connected in one piece. The upper cooling cavity (9) is connected to the output end of the plasma spray gun (8). The lower cooling cavity (10) has a sliding material taking door. Both the upper cooling cavity (9) and the lower cooling cavity (10) are provided with a water inlet and a water outlet.

8. The device for preparing boron nitride nanotubes using direct current plasma according to claim 7, characterized in that: The exhaust gas treatment module further comprises an exhaust gas treatment module, wherein the exhaust gas treatment module comprises an exhaust gas pipe and an exhaust gas treatment device (13), one end of the exhaust gas pipe is connected to the lower cooling cavity (10), and the other end is connected to the exhaust gas treatment device (13), and a safety valve (11) and a pressure gauge (12) are provided on the exhaust gas pipe.

9. A method for preparing boron nitride nanotubes using direct current plasma, characterized in that: The following steps are involved: S1: Cooling the water-cooling cavity with cooling water: S2: Control the plasma spray gun (8) to generate DC plasma; S3: feeding boron-containing raw materials and reaction gases to a plasma spray gun (8) to prepare boron nitride nanotubes; S4: The boron nitride nanotubes are sent into a water-cooling chamber through a plasma spray gun (8) for cooling.

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