Method for producing boron powder

Abstract

To provide a simple method for producing boron powder with reduced oxygen content.SOLUTION: A method for producing boron powder comprises a step of heat-treating a boron powder raw material in a hydrogen distribution atmosphere at a temperature of 1000°C or higher.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to a method for producing boron powder. [Background technology]

[0002] Boron (B) powder has been used for a variety of purposes, such as glass applications and boron fiber applications. In recent years, magnesium diboride (MgB 2 ) is being considered for use as a precursor for superconducting materials. Boron used as a precursor for superconducting materials is required to have even less impurities than conventional boron powder. For example, Patent Document 1 reports that the oxygen and nitrogen contents are reduced by heat treating a suspension obtained by adding a strong acid to elemental boron in the presence of alcohol. Patent Document 2 reports a method of removing organic contaminants from contaminated boron powder by heating at about 500°C in a hydrogen atmosphere. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2012-501942 [Patent Document 2] JP 2013-100215 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the method of Patent Document 1, not only are many steps required to reduce the amount of oxygen, but it is difficult to apply general-purpose manufacturing equipment, which tends to increase manufacturing costs. In addition, although the method of Patent Document 2 has a small number of steps, it is not suitable for reducing the amount of oxygen.

[0005] An object of the present disclosure is to provide a simple method for producing boron powder having a reduced oxygen content. [Means for solving the problem]

[0006] The present inventors have investigated the reduction of the oxygen content of boron powder, and as a result, have focused on the heat treatment temperature in hydrogen reduction and found that the oxygen content can be effectively reduced by setting the heat treatment temperature to a specific temperature.

[0007] That is, the present invention is as described in the claims, and the gist of the present disclosure is as follows. [1] A method for producing boron powder, comprising the steps of heat treating a boron powder raw material at 1000°C or higher in a hydrogen flowing atmosphere. [2] The method according to [1] above, wherein the oxygen content of the boron powder raw material is 1.0 ppm by mass or more. [3] The method according to [1] or [2] above, wherein the oxygen content of the boron powder is 10 mass% or less. [4] The method for producing a hydrogen gas according to any one of [1] to [3] above, wherein the hydrogen flow rate in the hydrogen flow atmosphere is 0.1 L / min or more. [5] A method for purifying boron powder, comprising the step of heat-treating boron powder at 1000°C or higher in a hydrogen flowing atmosphere. Effect of the Invention

[0008] The present disclosure provides a simple method for producing boron powder with a reduced oxygen content. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present disclosure will be described in detail below. However, the following description of the components is merely an example of an embodiment of the present disclosure, and the present disclosure is not limited to the contents thereof.

[0010] The present embodiment is a method for purifying boron powder, which is characterized by having a step of heat treating a boron powder raw material in a hydrogen flow atmosphere at 1000° C. or higher. This makes it possible to use general-purpose manufacturing equipment and efficiently reduce oxygen in the boron powder.

[0011] This embodiment includes a step of heat treating the boron powder raw material at 1000° C. or higher in a hydrogen flow atmosphere (hereinafter also referred to as a “heat treatment step”).

[0012] A boron powder raw material is provided in the heat treatment step. The boron powder raw material is a powder of boron (B) and has a high oxygen (O) content. The oxygen content of the boron powder raw material can be, for example, 1 mass ppm or more and 15 mass % or less.

[0013] The BET specific surface area of ​​the boron powder raw material is 10m 2 / g or more 400m 2 For example, it can be exemplified as being equal to or less than 1 / g.

[0014] The shape of the raw material boron powder to be subjected to the heat treatment step may be any shape, but it is preferably a molded body because it is easy to handle after the heat treatment. The molded body may be a molded body obtained by molding using tablet molding.

[0015] In the heat treatment step, the boron powder raw material is heat-treated in a hydrogen atmosphere, and the hydrogen atmosphere is preferably under a hydrogen stream. It is considered that the heat treatment under a hydrogen stream promotes hydrogen reduction of the surface oxide layer present on the surface of the boron powder raw material, and the amount of oxygen is more easily reduced. The flow rate of hydrogen is, for example, 0.1 L / min or more.

[0016] The heat treatment temperature in the heat treatment step is 1000°C or higher, and preferably 1200°C or higher. If the heat treatment temperature is lower than this, the reduction reaction does not proceed. The heat treatment temperature may be any temperature at which boron does not melt, and the upper limit is, for example, 2000°C. A preferred heat treatment temperature is, for example, 1000°C or higher and 2000°C or lower.

[0017] The temperature increase rate up to the heat treatment can be, for example, 30° C. / min or less, and the temperature decrease rate can be, for example, 30° C. / min or less.

[0018] The holding time at the heat treatment temperature may be appropriately adjusted depending on the amount of boron powder raw material used in the treatment and the characteristics of the firing furnace used in the heat treatment, and may be, for example, from 1 hour to 24 hours.

[0019] By undergoing the heat treatment step, the amount of oxygen in the boron powder raw material is reduced; for example, the oxygen content [mass %] is reduced to 50% or less of the oxygen content [mass %] of the boron powder raw material before the heat treatment step.

[0020] The oxygen content of the boron powder obtained by the manufacturing method of this embodiment can be, for example, from 1.0 ppm by mass to 10% by mass.

[0021] The manufacturing method of this embodiment may also be used as a method for purifying boron powder. EXAMPLES

[0022] The present disclosure will be described below with reference to examples. However, the present disclosure is not limited to these examples. (Oxygen content measurement)

[0023] The oxygen content of the boron powder was measured by an inert gas fusion-infrared absorption method using an oxygen / nitrogen analyzer (device name: LECO ON736, manufactured by Leco). (BET specific surface area measurement)

[0024] The BET specific surface area of ​​the boron powder was measured using an automatic specific surface area / pore distribution measuring device (device name: TriStar 3000, manufactured by Shimadzu Corporation). Example 1

[0025] As a boron powder raw material, it has a BET specific surface area of ​​62m 2 The boron powder raw material had an oxygen content of 12.5 mass%. The boron powder raw material was fed at 300 kgf / cm 2 The mixture was uniaxially pressed at a pressure of 1000 g for 1 minute to form a tablet, and the tablet was then placed in a tubular furnace and heat-treated in a hydrogen atmosphere under the following conditions. Heating rate: 20℃ / min Cooling rate: 20℃ / min Hydrogen flow rate: 1L / min Processing temperature: 1400℃ Processing time: 5 hours

[0026] After the heat treatment, the oxygen content of the obtained boron powder was 6.7% by mass. This example confirmed that the oxygen content was reduced by 5.8% by mass, and that the oxygen content was efficiently reduced by treatment in a hydrogen atmosphere at 1000°C or higher.

Claims

1. A method for producing boron powder, comprising the step of heat treating a boron powder raw material at 1000° C. or higher in a hydrogen flowing atmosphere.

2. The method according to claim 1 , wherein the oxygen content of the boron powder raw material is 1.0 ppm by mass or more.

3. The method according to claim 1 or 2, wherein the oxygen content of the boron powder is 10 mass% or less.

4. 3. The method according to claim 1, wherein the flow rate of hydrogen in the hydrogen flow atmosphere is 0.1 L / min or more.

5. A method for purifying boron powder, comprising the step of heat treating boron powder at 1000° C. or higher in a hydrogen flowing atmosphere.