A method for preparing hexagonal boron nitride nanowires

Abstract

The present invention relates to a method for preparing hexagonal boron nitride nanowires, which is characterized by comprising the steps of: placing a boride, a porous activated material and a deposition plate in a first low temperature zone, a high temperature zone and a second low temperature zone of a reaction device, respectively, wherein the first low temperature zone, the high temperature zone and the second low temperature zone are arranged in sequence; raising the temperature, introducing a reducing gas into the reaction device, and performing a reduction nitridation reaction in a flowing reducing atmosphere; and stripping off the product deposited on the deposition plate to obtain hexagonal boron nitride nanowires. The method for preparing hexagonal boron nitride nanowires of the present invention is simple and easy to operate, has relatively low requirements on reaction conditions, reduces the production cost of hexagonal boron nitride nanowires, shortens the production cycle, and improves production efficiency. The prepared hexagonal boron nitride nanowires can be used in many fields such as polymer composite materials, military and aerospace, and provides a new idea for the industrialized and efficient preparation of hexagonal boron nitride nanowires.

Description

Technical Field

[0001] The invention relates to the technical field of inorganic non-metallic materials, and in particular to a method for preparing hexagonal boron nitride nanowires. Background Art

[0002] Hexagonal boron nitride is a material with high temperature resistance, corrosion resistance, high thermal conductivity, high insulation and excellent mechanical properties. Boron nitride-based nanomaterials have great potential for practical application in many fields. The characteristics of high temperature resistance and oxidation resistance make hexagonal boron nitride nanowires have broad application prospects in nano devices and products working under harsh conditions such as high temperature oxidizing atmospheres. For example, its stable wide band gap and excellent high temperature oxidation resistance make it possible to become an excellent high temperature wide band gap semiconductor material; excellent mechanical properties make hexagonal boron nitride nanowires a reinforced phase material for composite materials used under high temperature conditions; high insulation and high thermal conductivity characteristics make hexagonal boron nitride nanowires, which can be used to prepare boron nitride composite materials with high thermal conductivity, high insulation and excellent dielectric properties, solving bottleneck problems in industries such as high-frequency communications.

[0003] At present, the main preparation methods of boron nitride nanotubes include arc discharge method, template method, inorganic reaction method, organic precursor method, electrospinning method, mechanical ball milling method and high temperature chemical vapor deposition method. Among them, mechanical ball milling method and high temperature chemical vapor deposition method are the current mainstream preparation methods. However, the mechanical ball milling method usually takes more than 100 hours, which takes a long time. A large amount of impurities will be introduced during the ball milling process. At the same time, the product structure is disordered and the diameter of the product is not easy to control; the yield of the arc method is very low; the boron nitride nanowires prepared by the inorganic reaction method often use a large amount of catalysts, the yield and purity are very low and contain many impurities, which is not conducive to the application of the product in composite materials; the organic precursor method requires environmental protection, which makes the operability complicated, and organic volatiles in the reaction process cause environmental pollution. Although hexagonal boron nitride nanowires can be obtained by the above methods, the yield is generally low, the conditions in the preparation process are harsh, and the environmental pollution is large; it cannot meet the market's urgent demand for hexagonal boron nitride nanowire products and the demand for industrial preparation. Therefore, how to obtain a preparation method for hexagonal boron nitride nanowires with high purity, high yield, low cost and green environmental protection is a difficult problem that needs to be solved urgently. Summary of the invention

[0004] The purpose of the present invention is to solve the above problems and provide a method for preparing hexagonal boron nitride nanowires.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing hexagonal boron nitride nanowires comprises the following steps:

[0007] The boride, the porous activation material and the deposition plate are respectively arranged in the first low-temperature zone, the high-temperature zone and the second low-temperature zone of the reaction device, wherein the first low-temperature zone, the high-temperature zone and the second low-temperature zone are arranged in sequence;

[0008] Raising the temperature, introducing a reducing gas into the reaction device, and performing a reduction nitridation reaction in a flowing reducing atmosphere;

[0009] The product deposited on the deposition plate is peeled off to obtain hexagonal boron nitride nanowires.

[0010] Preferably, the diameter of the hexagonal boron nitride nanowires is 10-30 nm.

[0011] Preferably, the boride comprises one or more of ammonium pentaborate, borax, boric acid or boric oxide.

[0012] Preferably, the boride comprises one or more of boric acid or boron oxide.

[0013] Preferably, the porous activation material comprises one or both of the porous carbon mold or porous carbon powder.

[0014] Preferably, the porous activated material is made of one or more of carbon quantum dots, carbon nanotubes, carbon fibers or graphite.

[0015] Preferably, when the reducing gas is introduced into the reaction device, the flow rate of the reducing gas is 40-1000 mL / min.

[0016] Preferably, during the reduction nitridation reaction, the heating temperature of the reaction device is 1300-1900° C., the heating rate is 3-10° C. / min, and the reaction time of the reduction nitridation reaction is 1-10 h.

[0017] Preferably, during the reduction nitridation reaction, the temperature of the first low temperature zone and / or the second low temperature zone is 1000-1300°C, and the temperature of the high temperature zone is 1500-1700°C.

[0018] Preferably, the deposition plate comprises one or both of a carbon plate or a steel plate.

[0019] The beneficial effects produced by the present invention include at least:

[0020] The method for preparing hexagonal boron nitride nanowires of the present invention is to divide the reaction device into three temperature zones, gasify the boride in the first low-temperature zone in a flowing high-temperature reducing atmosphere and blow it to the high-temperature zone, and after being activated by the porous activation material in the high-temperature zone, deposit it on the deposition plate in the second low-temperature zone to form hexagonal boron nitride nanowires with a diameter of 10-30nm. The method for preparing hexagonal boron nitride nanowires of the present invention is simple and easy to operate, has relatively low requirements on reaction conditions, reduces the production cost of hexagonal boron nitride nanowires, shortens the production cycle, and improves production efficiency. The prepared hexagonal boron nitride nanowires can be used in many fields such as polymer composites, military and aerospace, and provides a new idea for the industrialized and efficient preparation of hexagonal boron nitride nanowires. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a SEM test image of hexagonal boron nitride nanowires obtained by the preparation method of the present invention;

[0022] Figure 2 Another SEM test image of hexagonal boron nitride nanowires obtained by the preparation method of the present invention;

[0023] Figure 3 This is an XRD test spectrum of hexagonal boron nitride nanowires obtained by the preparation method of the present invention. DETAILED DESCRIPTION

[0024] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0026] In the present invention, descriptions such as “first”, “second”, etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features.

[0027] The method for preparing hexagonal boron nitride nanowires of the present invention particularly relates to a process for preparing hexagonal boron nitride nanowires by vapor deposition in one step using a carbon source as an activator, comprising the steps of:

[0028] The boride, the porous activation material and the deposition plate are respectively arranged in the first low temperature zone, the high temperature zone and the second low temperature zone of the reaction device, wherein the first low temperature zone, the high temperature zone and the second low temperature zone are arranged in sequence;

[0029] Raising the temperature, introducing a reducing gas into the reaction device, and performing a reduction nitridation reaction in a flowing reducing atmosphere;

[0030] The product deposited on the deposition plate is peeled off to obtain hexagonal boron nitride nanowires.

[0031] The method for preparing hexagonal boron nitride nanowires of the present invention is to divide the reaction device into three temperatures, heat and vaporize the boride in the first low temperature zone and flow it to the porous activation material arranged in the high temperature zone along with the flowing reducing gas, and the vaporized boride is fully activated after passing through the porous activation material to be converted into B 2 O 2 and other active substances; and finally, hexagonal boron nitride nanowires are deposited on the deposition plate in the second low temperature zone. The preparation method of hexagonal boron nitride nanowires of the present invention is concise and efficient, has low cost of raw materials, relatively low requirements on reaction conditions, reduces the production cost of hexagonal boron nitride nanowires, shortens the production cycle, improves production efficiency, and has less harm to the environment during the reaction process. The prepared hexagonal boron nitride nanowires can be used in many fields such as polymer composite materials, military and aerospace, and provides a new idea for the industrial and efficient preparation of hexagonal boron nitride nanowires.

[0032] The diameter of the hexagonal boron nitride nanowire is 10-30 nm.

[0033] The boride comprises one or more of ammonium pentaborate, borax, boric acid or boric oxide. Further preferably, the boride comprises one or more of boric acid or boric oxide.

[0034] The porous activation material includes one or both of the porous carbon mold and the porous carbon powder. The porous activation material has a high specific surface area and reducibility, so that the gaseous boride after gasification can be fully activated after passing through, thereby promoting the subsequent efficient transformation of the gaseous boride into the solid hexagonal boron nitride nanowire.

[0035] The porous activation material is made of one or more of carbon quantum dots, nano carbon nanotubes, carbon fibers or graphite, etc. Optionally, when the porous activation material is the porous carbon mold, the porous carbon mold is made into a shape that fits the middle area of ​​the reaction device and is arranged in the reaction device; when the porous activation material is the porous carbon powder, the porous carbon powder is placed in a crucible and arranged in the middle of the reaction device.

[0036] Preferably, when the reducing gas is introduced into the reaction device, the flow rate of the reducing gas is 40-1000 mL / min. The reducing gas comprises a mixture of one or both of ammonia and nitrogen. The reduction nitridation reaction of the present invention is carried out under a flowing reducing atmosphere. There is no specific requirement for the pressure in the reaction device, and it can be carried out under normal pressure. The production and preparation conditions are simple.

[0037] Preferably, during the reduction nitridation reaction, the heating temperature of the reaction device is 1300-1900° C., the heating rate is 3-10° C. / min, and the reaction time of the reduction nitridation reaction is 1-10 h.

[0038] Preferably, during the reduction nitridation reaction, the temperature of the first low temperature zone and / or the second low temperature zone is 1000-1300°C, and the temperature of the high temperature zone is 1500-1700°C.

[0039] Preferably, the deposition plate comprises one or both of a carbon plate and a steel plate. Further, the deposition plate is arranged in a direction parallel to the axial direction of the tube furnace.

[0040] Example 1

[0041] A method for preparing hexagonal boron nitride nanowires comprises the following steps:

[0042] In this embodiment, the reaction device is preferably a tubular furnace, wherein the boride is disposed at the air inlet region of the tubular furnace, the porous activation material is disposed at the middle of the tubular furnace, and the deposition plate is disposed at the air outlet region of the tubular furnace; the boride is boron oxide;

[0043] Optionally, in this embodiment, when the porous carbon mold is selected, the porous carbon mold is made into a shape that matches the furnace diameter of the tubular furnace and is placed in the tubular furnace; when the porous activated material is the porous carbon powder, the porous carbon powder is placed in a crucible and arranged in the middle of the tubular furnace.

[0044] The tube furnace is heated to 1500°C at a rate of 3-5°C / min, and a reduction nitridation reaction is carried out in flowing ammonia or nitrogen for 1-10 hours; then the product deposited on the deposition plate is peeled off to finally obtain hexagonal boron nitride nanowires. Figure 1 and Figure 2 As shown, the diameter of the hexagonal boron nitride nanowires obtained by the present invention is 10-30nm; Figure 3 As shown, the diffraction peaks in the XRD spectrum are diffraction peaks of boron nitride, and no other impurity peaks appear, indicating that the hexagonal boron nitride nanowires obtained by the present invention have high purity and high crystallinity, which lays a good foundation for the preparation of high thermal conductivity materials.

[0045] Example 2

[0046] Compared with Example 1, the preparation method of hexagonal boron nitride nanowires in Example 2 is different in that:

[0047] In this embodiment, the tube furnace is heated to 1700°C at a rate of 5-7°C / min, and the reduction nitridation reaction is carried out in a mixed atmosphere of flowing ammonia and nitrogen for 1-10 hours; then the product deposited on the deposition plate is peeled off to finally obtain hexagonal boron nitride nanowires. The boride is a mixture of boron oxide and boric acid. The diameter of the obtained hexagonal boron nitride nanowires is 10-30nm, with high purity and high crystallinity.

[0048] Example 3

[0049] Compared with Example 1, the preparation method of hexagonal boron nitride nanowires in Example 3 is different in that:

[0050] In this embodiment, the tube furnace is heated to 1900°C at a rate of 7-9°C / min, and the reduction nitridation reaction is carried out in flowing ammonia for 1-10 hours; then the product deposited on the deposition plate is peeled off to finally obtain hexagonal boron nitride nanowires. The boride is a mixture of pyroboric acid and boron oxide. The obtained hexagonal boron nitride nanowires have a diameter of 10-30nm, have high purity and high crystallinity.

[0051] Example 4

[0052] Compared with Example 1, the preparation method of hexagonal boron nitride nanowires in Example 4 is different in that:

[0053] In this embodiment, the tube furnace is heated to 1500°C at a rate of 3-6°C / min, and the reduction nitridation reaction is carried out in flowing ammonia for 1-10 hours; then the product deposited on the deposition plate is peeled off to finally obtain hexagonal boron nitride nanowires. The boride is a mixture of pyroboric acid and boron oxide. The obtained hexagonal boron nitride nanowires have a diameter of 10-30nm, have high purity and high crystallinity.

[0054] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0055] The above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing hexagonal boron nitride nanowires, characterized in that: Includes steps: The boride, the porous activation material and the deposition plate are respectively arranged in the first low-temperature zone, the high-temperature zone and the second low-temperature zone of the reaction device, wherein the first low-temperature zone, the high-temperature zone and the second low-temperature zone are arranged in sequence; Raising the temperature, introducing a reducing gas into the reaction device, and performing a reduction nitridation reaction in a flowing reducing atmosphere; peeling off the product deposited on the deposition plate to obtain hexagonal boron nitride nanowires; The boride comprises one or more of boric acid or boron oxide; The porous activation material includes one or both of a porous carbon mold or a porous carbon powder; During the reduction nitridation reaction, the heating temperature of the reaction device is 1300-1900°C, the heating rate is 3-10°C / min, and the reaction time of the reduction nitridation reaction is 1-10h; During the reduction nitridation reaction, the temperature of the first low temperature zone and / or the second low temperature zone is 1000-1300° C., and the temperature of the high temperature zone is 1500-1700° C.; The deposition plate includes one or both of a carbon plate and a steel plate.

2. The method for preparing hexagonal boron nitride nanowires according to claim 1, characterized in that: The diameter of the hexagonal boron nitride nanowire is 10-30 nm.

3. The method for preparing hexagonal boron nitride nanowires according to claim 1, characterized in that: The porous activated material is made of one or more of carbon quantum dots, carbon nanotubes, carbon fibers or graphite.

4. The method for preparing hexagonal boron nitride nanowires according to claim 1, characterized in that: When the reducing gas is introduced into the reaction device, the flow rate of the reducing gas is 40-1000 mL / min.

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