Method for preparing high-density uniform boron nitride nanotube film

Abstract

The invention discloses a method for preparing a high-density uniform boron nitride nanotube film. According to the method, a high-temperature annealing method is adopted, a stainless steel substrate is subjected to electrochemical polishing in advance, after the surface is mixed and infiltrated through double catalyst sources, the stainless steel substrate is put into a high-temperature area of a tubular furnace for growth of boron nitride nanotubes, and the high-compactness boron nitride nanotube film can be obtained. A mixture of a catalyst and a source body on the surface of stainless steel can form various nucleation clusters such as triangular nucleation clusters and quadrilateral nucleation clusters, nucleation sites are formed on the nucleation clusters, boron nitride nanotubes are generated, a whole uniform and compact boron nitride nanotube film is finally formed, the boron nitride nanotubes have excellent mechanical, optical and thermodynamic properties, and the boron nitride nanotubes have excellent mechanical, optical and thermodynamic properties. The method has extremely high application potential in the aspects of nano photonics, microelectronic devices and the like. The preparation method is simple and rapid in preparation process and low in cost, and further possibility is provided for industrial application of the boron nitride nanotube material.

Description

Technical Field

[0001] The invention belongs to the field of materials and relates to a method for preparing boron nitride nanotubes, in particular to a method for preparing a highly dense and uniform boron nitride nanotube film. Background Art

[0002] Boron nitride nanotubes have a similar structure to carbon nanotubes, both of which are tubular nanomaterials formed by curling up a hexagonal lattice structure. The basic lattice of boron nitride nanotubes is a hexagonal network of alternating boron atoms and nitrogen atoms, forming a sp 2 Strong covalent bonds of hybridization. The high thermal conductivity and thermal stability of boron nitride nanotubes make them ideal thermal management materials, which can be used for heat dissipation of electronic equipment and thermal protection materials in other high temperature environments. Boron nitride nanotubes are mid-infrared optically transparent and infrared active, and are suitable for optical devices in the infrared band, such as infrared detectors, filters and optical sensors. Although boron nitride nanotubes show excellent performance in theory, their research and development in practical applications are still in the early stages. The existing preparation process of boron nitride nanotubes is relatively complicated, the yield is low and uneven, especially compared with carbon nanotubes, the preparation method of BNNT has not been fully explored. The present invention adopts a simple and efficient method to achieve the preparation of high-density and uniform thin films of boron nitride nanotubes, which provides an important reference for boron nitride nanotubes to play an important role in high-tech fields (such as aerospace, electronic devices, infrared optics and energy materials). Summary of the invention

[0003] The purpose of the present invention is to provide a method for preparing a high-density and uniform boron nitride nanotube film.

[0004] The above technical problem of the present invention is solved by the following scheme.

[0005] The invention discloses a method for preparing a high-density and uniform boron nitride nanotube film, comprising: electrochemically polishing a stainless steel substrate, and then growing boron nitride nanotubes by a high-temperature annealing method.

[0006] In the above method, the stainless steel substrate is 304 or 316 stainless steel.

[0007] The thickness of the 304 or 316 stainless steel substrate is 100-1500 μm, preferably 1000 μm.

[0008] The ratio of the deionized water, phosphoric acid, ethanol, isopropanol and urea in milliliters is 9:10:5:2. The volume of the commonly used polishing liquid can be 300 mL. The amount of urea is 0.8-1.0 g per 100 mL of the total amount of other components.

[0009] The voltage is 10-15V; specifically 12V;

[0010] The current is 3-6A; specifically 5A;

[0011] The time is 15-20 minutes; specifically 18 minutes.

[0012] The purpose of the electrochemical polishing is to remove surface contaminants and oxide layers;

[0013] In the growth step, the temperature is 1000-1200°C;

[0014] The heating rate is 30-40 minutes to heat to 1000-1200°C; specifically, it can be 35 minutes to heat to 1100°C;

[0015] Maintain at 1100°C for 10-60 minutes; specifically, 30-60 minutes;

[0016] The mixing ratio of nitrogen and hydrogen used is 1-20:1-10; specifically 9:1;

[0017] The flow rate of the nitrogen and hydrogen mixed gas is 20-50 sccm, specifically 30 sccm.

[0018] In the growth step, the boron source used is boron powder; specifically, nano-grade high-purity boron powder;

[0019] In the growth step, the catalyst used is a dual catalyst, specifically iron and aluminum oxide; more specifically nano-iron and nano-aluminum oxide.

[0020] In the growth step, the boron source, nano-alumina and nano-iron are mixed with ethanol (2-10 mL) at a mass ratio of 12:4:1, and uniformly mixed by water bath ultrasound for 10-20 min to obtain a dual catalyst source mixture;

[0021] The dual catalyst source mixture infiltrates the stainless steel substrate; specifically, spin coating.

[0022] The method further comprises: after the growth is completed, the tube furnace is rapidly cooled to 100° C. and then the hydrogen is turned off, and after the tube furnace is cooled to room temperature, the introduction of the nitrogen and hydrogen mixed gas is stopped.

[0023] In addition, the highly dense and uniform boron nitride nanotube film prepared according to the above method also falls within the protection scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is an image of a uniform boron nitride nanotube film prepared in Example 1.

[0025] Figure 2 is a scanning electron microscope image of the boron nitride nanotubes prepared in Example 1.

[0026] Figure 3 This is the Raman spectrum of the boron nitride nanotube film prepared in Example 1.

[0027] Figure 4 This is an image of a uniform boron nitride nanotube film prepared in Example 2.

[0028] Figure 5 This is a scanning electron microscope image of the boron nitride nanotubes prepared in Example 2.

[0029] Figure 6 This is an optical microscope image of the boron nitride nanotubes prepared in Example 3. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below by way of embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] Example 1

[0032] The cut stainless steel substrate (2×1.5cm) was electrochemically polished with a polishing solution consisting of 104mL of deionized water, 115mL of phosphoric acid, 58mL of ethanol, 23mL of isopropanol and 2.8g of urea; after polishing, it was ultrasonically cleaned for 10min and the surface was infiltrated with the dual catalyst source mixture; after the tube furnace was heated to 1050°C, the stainless steel with the surface infiltrated with the dual catalyst source mixture was placed in the center of the tube furnace, and a nitrogen and hydrogen mixed gas with a flow rate of 30sccm was introduced for 50min, and then cooled to room temperature and the introduction of the nitrogen and hydrogen mixed gas was stopped, and the growth was completed.

[0033] Figure 1 This is the stainless steel substrate taken out from the tube furnace after the tube furnace has cooled to room temperature in this embodiment. The white surface is the boron nitride nanotube film; Figure 2 This is a scanning electron microscope image of the boron nitride nanotubes prepared in this example, where the boron nitride nanotubes are interwoven to form a boron nitride nanotube film; Figure 3 for Figure 1 This is a Raman spectrum of the boron nitride nanotube film prepared in this example.

[0034] Example 2

[0035] The cut stainless steel substrate (2×1.5cm) was electrochemically polished, and the polishing liquid used was composed of 104mL of deionized water, 115mL of phosphoric acid, 58mL of ethanol, 23mL of isopropanol and 2.8g of urea; after polishing, ultrasonic cleaning was carried out for 10min, and the surface was infiltrated with the dual catalyst source mixture; after the tube furnace was heated to 1100℃, the stainless steel with the surface infiltrated with the dual catalyst source mixture was placed in the center of the tube furnace, and a nitrogen and hydrogen mixed gas with a flow rate of 20sccm was introduced for 40min, and the introduction of the nitrogen and hydrogen mixed gas was stopped when it was cooled to room temperature, and the growth was completed.

[0036] Figure 4 This is the stainless steel substrate taken out from the tube furnace after the tube furnace has cooled to room temperature in this embodiment. The white surface is the boron nitride nanotube film; Figure 5 This is a scanning electron microscope image of the boron nitride nanotubes prepared in this example.

[0037] Example 3

[0038] The cut stainless steel substrate (2×1.5cm) was electrochemically polished, and the polishing liquid used was composed of 104mL of deionized water, 115mL of phosphoric acid, 58mL of ethanol, 23mL of isopropanol and 2.8g of urea; after polishing, ultrasonic cleaning was carried out for 10min, and the surface was infiltrated with the dual catalyst source mixture; after the tube furnace was heated to 1100℃, the stainless steel with the surface infiltrated with the dual catalyst source mixture was placed in the center of the tube furnace, and a nitrogen and hydrogen mixed gas with a flow rate of 20sccm was introduced for 10min, and the introduction of the nitrogen and hydrogen mixed gas was stopped when it was cooled to room temperature, and the growth was completed.

[0039] Figure 6 The optical microscope image of the boron nitride nanotubes prepared in this example shows the initial stage of the growth of the boron nitride nanotube film, where the nucleation sites on the clusters grow into individual boron nitride nanotubes.

[0040] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0041] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing a high-density uniform boron nitride nanotube film, characterized in that: The stainless steel substrate needs to be electrochemically polished, the dual catalyst and the source body are mixed and infiltrated into the substrate surface, and then the boron nitride nanotubes are grown by high temperature annealing method.

2. The method for preparing a high-density uniform boron nitride nanotube film according to claim 1, characterized in that: The stainless steel substrate is 304 or 316 stainless steel with a thickness of 100-1500 μm.

3. The method for preparing a high-density uniform boron nitride nanotube film according to claim 1, characterized in that: The polishing liquid used for the electrochemical polishing is composed of deionized water, phosphoric acid, ethanol, isopropanol and urea, and the specific dosage ratio is 9:10:5:

2. The dosage of urea is 0.8-1.0g per 100ml of the total amount of other components.

4. A method for preparing a high-density uniform boron nitride nanotube film according to claims 1-3, characterized in that: The electrochemical polishing voltage is 10-15V; specifically 12V; The current is 3-6A; specifically 5A; The time is 15-20 minutes; specifically 18 minutes.

5. The method for preparing a high-density uniform boron nitride nanotube film according to claim 1, characterized in that: In the growth step, the temperature is 1000-1200°C; The heating rate is 30-40min to 1000-1200℃; Keep for 10-60 minutes; specifically 50 minutes; The mixing ratio of nitrogen and hydrogen used is 1-20:1-10; specifically 9:1; The flow rate of the nitrogen and hydrogen mixed gas is 20-50 sccm.

6. The method for preparing a high-density uniform boron nitride nanotube film according to claim 1, characterized in that: In the growth step, the boron source used is boron powder, specifically nano-level high-purity boron powder.

7. The method for preparing a high-density uniform boron nitride nanotube film according to claim 1, characterized in that: In the growth step, the catalyst used is a dual catalyst, specifically iron and aluminum oxide; more specifically nano-iron and nano-aluminum oxide.

8. The method for preparing a high-density and uniform boron nitride nanotube film according to claim 1, characterized in that: The boron source, nano-alumina and nano-iron are respectively mixed with ethanol (2-10 mL) at a mass ratio of 12:4:1, and uniformly mixed by water bath ultrasound for 10-20 min.

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