JP3658622B2 - Method for producing boron carbide nanowire - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The invention of this application relates to a method for producing boron carbide nanowires. More specifically, the invention of this application relates to boron carbide nanowires that are useful as lightweight, high heat-resistant, high-strength materials in fields such as heat-resistant and fire-resistant clothing, neutron absorbers for the nuclear industry, and thermal and electrical energy conversion. It is.
[0002]
[Prior art]
A plasma CVD method is known as a method for synthesizing a boron carbide nanomaterial (see, for example, Non-Patent Document 1). In addition, a method for producing an oriented boron carbide nanowire using porous alumina as a template has been proposed (see, for example, Non-Patent Document 2).
[0003]
Furthermore, a method for synthesizing boron carbide nanowires using carbon nanotubes as a template has also been proposed (see, for example, Non-Patent Document 3).
[0004]
[Non-Patent Document 1]
Zhang, D. and 4 others, Journal of Material Science Letters (J. Mater. Sci. Lett.) 1999, Volume 1, p. 349
[Non-Patent Document 2]
Pender, M. et al., Chemical Materials (Chem. Mater.), 2000, Vol. 12, p. 280
[Non-Patent Document 3]
Dai, H. and 4 others, Nature, 1995, Volume 375, p. 769
[0005]
[Problems to be solved by the invention]
However, the above-described method has problems such that a large amount of boron carbide nanowires cannot be produced and the production cost is high.
[0006]
The invention of this application has been made in view of such circumstances, and a new method for producing a boron carbide nanowire that can be easily manufactured simply by heating a raw material at a high temperature and can solve the above problems. Providing is a problem to be solved.
[0007]
[Means for Solving the Problems]
The invention of this application, as to solve the above problem, boron, boron oxide and carbon was added B ₄ N ₃ O ₂ H, is reacted at a high temperature of 1000 ° C. to 2100 ° C. in a nitrogen atmosphere, carbonized provides a method for manufacturing boron carbide nanowires characterized that you coat the surface of the boron nanowires boron nitride (claim 1).
[0008]
The invention of this application relates to the invention of claim 1 and provides, as one aspect, that the carbon is carbon black (claim 2).
[0011]
Hereinafter, the manufacturing method of the boron carbide nanowire of the invention of this application will be described in more detail with reference to examples.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
For example, boron, boron oxide and carbon are placed in a cylindrical crucible, the crucible is placed in a high frequency induction heating furnace, heated to a high temperature of 1000 ° C. to 2100 ° C. in an argon stream, and kept at that temperature for about 2 hours. React. If it is lower than 1000 ° C., the reaction rate decreases and the yield in a short time decreases. When the temperature exceeds 2100 ° C., the evaporation of the raw material, the shape change of the product, etc. occur. After completion of the reaction, a black-gray fibrous deposit is deposited on the upper wall of the crucible. This deposit is a boron carbide nanowire. Varying the molar ratio of starting materials in the raw material yields various forms of the product. For example, when the molar ratio of carbon is increased, the content of nanowires is increased, and when the molar ratio of carbon is decreased, many products such as flakes are formed.
[0014]
Also , when B ₄ N ₃ O ₂ H is added to the raw materials boron, boron oxide and carbon and heated to a high temperature of 1000 ° C. to 2100 ° C. in a nitrogen atmosphere, the surface of the boron carbide nanowire is coated with boron nitride. .
[0015]
When carbon black is used as the raw material carbon, carbon black is suitable because it is amorphous and inexpensive.
[0016]
Since the manufacturing method of the boron carbide nanowire of the invention of this application only heats the raw material as described above, it has a great economic advantage over any of the manufacturing methods previously proposed. It also makes it possible to produce a large amount of boron carbide nanowires.
[0017]
【Example】
( Reference Example 1)
Carbon black, boron powder (purity 99%) and boron oxide (purity 99.99%) were placed in a cylindrical crucible in a molar ratio of 1: 2: 1. This crucible was placed in a high frequency induction heating furnace, rapidly heated in an argon stream, heated to 1650 ° C. within 15 minutes and held at this temperature for 2 hours. After the reaction was completed, a fibrous product was deposited on the upper wall of the crucible.
[0018]
The crystal structure of the product was analyzed by X-ray diffraction. The result is the X-ray diffraction pattern shown in FIG. This X-ray diffraction pattern is consistent with the structure of B ₄ C (a = 5.6003Å, c = 12.086Å) or B ₁₃ C ₂ (a = 5.6330Å, c = 12.1640Å), and shows other structures It was found that it was a high purity boron carbide.
[0019]
The results of observing the product with a scanning electron microscope are the photographs in FIGS. 2a and 2b.
[0020]
It was confirmed from the photographs of FIGS. 2a and 2b that the nanowire was very homogeneous. The diameter of the nanowire was 50 nm to 200 nm.
( Reference Example 2)
The same procedure as in Reference Example 1 was performed except that the molar ratio of carbon black, boron powder and boron oxide was changed to 1: 8: 4. In Reference Example 2, the number of moles of carbon black is reduced compared to Reference Example 1. As shown in the scanning electron micrographs of the products in FIGS. 3a and 3b, it was confirmed that flaky materials and platelet-like materials were generated in addition to boron carbide nanowires. Also, as shown in the scanning electron micrograph of FIG. 3c, bent nanowires were also obtained.
( Reference Example 3)
The same procedure as in Reference Example 1 was conducted except that carbon black containing 0.5 wt% iron and 0.1 wt% nickel was used as a starting material. As is apparent from FIG. 4a showing a scanning electron micrograph of the product, it was confirmed to be a nanowire. It is also confirmed that, in addition to nanowires having a diameter of 50 nm to 200 nm, nanowires having a diameter of 10 nm to 30 nm, which is smaller than the nanowire, are generated.
[0021]
Furthermore, from the scanning electron micrograph shown in FIG. 4b, it was confirmed that the tip of the nanowire was spherical. The spherical portion was found to be mainly composed of an iron component from the energy dispersive X-ray diffraction pattern shown in FIG. 4c.
(Example 1 )
It was added 20 wt% of B ₄ N ₃ O ₂ H relative to the total amount of the raw materials used in Reference Example 1, was produced carbon boron nanowires in the same manner as in Reference Example 1 in a nitrogen gas atmosphere. As shown in the transmission electron micrograph of FIG. 5, it was confirmed that the surface of the boron carbide nanowire was coated with boron nitride.
[0022]
Of course, the invention of this application is not limited by the above embodiments and examples. It goes without saying that various aspects are possible with respect to details such as the molar ratio of the starting materials, heating conditions, and the amount of additive added.
[0023]
【The invention's effect】
As described above in detail, the invention of this application makes boron carbide promising as a lightweight, high heat-resistant, high-strength material in fields such as heat-resistant and fire-resistant clothing, neutron absorbers for the nuclear industry, and thermal / electric energy conversion. A large amount of nanowires can be manufactured, and the manufacturing cost can be kept low.
[Brief description of the drawings]
1 is an X-ray diffraction pattern of a product obtained in Reference Example 1. FIG.
FIGS. 2a and 2b are scanning electron micrographs of the product obtained in Reference Example 1, respectively.
3 is a scanning electron micrograph of the product obtained in Reference Example 2, respectively.
4 a and b are scanning electron micrographs of the product obtained in Reference Example 3, respectively, and c is an energy dispersive X-ray diffraction pattern of a spherical tip.
5 is a scanning electron micrograph of the product obtained in Example 1. FIG.

Claims (2)

Wherein boron added B ₄ N ₃ O ₂ H boron oxide and carbon, are reacted at a high temperature of 1000 ° C. to 2100 ° C. in a nitrogen atmosphere, that you cover the surface of the boron carbide nanowires boron nitride A method for producing boron carbide nanowires. The method for producing a boron carbide nanowire according to claim 1 , wherein the carbon is carbon black .

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