阅读说明：本技术 碳纳米管阴极的制作方法、碳纳米管阴极及电子设备 (Method for manufacturing carbon nanotube cathode, carbon nanotube cathode and electronic device ) 是由 洪序达 贺思如 梁栋 郑海荣 于 2021-03-08 设计创作，主要内容包括：本申请公开了一种碳纳米管阴极的制作方法、碳纳米管阴极以及电子设备。该方法包括：提供一导电基板；对所述导电基板进行表面处理,以在所述导电基板的表面形成凹陷结构；利用所述碳纳米管浆料在所述导电基板的所述表面形成碳纳米管层,以形成所述碳纳米管阴极。通过上述方式,本申请能够提高基板和碳纳米管的结合强度,进而提高碳纳米管的场发射电流密度和稳定性,制备工艺简单,易于实现。(The application discloses a manufacturing method of a carbon nanotube cathode, the carbon nanotube cathode and an electronic device. The method comprises the following steps: providing a conductive substrate; carrying out surface treatment on the conductive substrate to form a concave structure on the surface of the conductive substrate; and forming a carbon nanotube layer on the surface of the conductive substrate by using the carbon nanotube slurry to form the carbon nanotube cathode. Through the mode, the bonding strength of the substrate and the carbon nano tube can be improved, the field emission current density and the stability of the carbon nano tube are further improved, the preparation process is simple, and the method is easy to realize.)

1. A method of making a carbon nanotube cathode, the method comprising:

providing a conductive substrate;

carrying out surface treatment on the conductive substrate to form a concave structure on the surface of the conductive substrate;

and forming a carbon nanotube layer on the surface of the conductive substrate by using the carbon nanotube slurry to form the carbon nanotube cathode.

2. The method of claim 1,

the surface treatment of the conductive substrate is performed to form a recessed structure on the surface of the conductive substrate, and the method includes:

cleaning the conductive substrate;

and placing the conductive substrate after the cleaning operation in an alkaline solution to form a concave structure on the surface of the conductive substrate.

3. The method of claim 2,

the cleaning operation of the conductive substrate includes:

performing ultrasonic operation on the conductive substrate;

cleaning the conductive substrate subjected to the ultrasonic operation by using ethanol;

and drying the conductive substrate after the cleaning operation.

4. The method of claim 1,

the method further comprises the following steps:

adding carbon nanotubes, ball milling beads, a binder and metal powder into a ball milling solvent to perform ball milling operation on the carbon nanotubes to form the carbon nanotube slurry.

5. The method of claim 4,

adding carbon nanotubes, ball milling beads, a binder and metal powder into a ball milling solvent to perform ball milling operation on the carbon nanotubes to form the carbon nanotube slurry, comprising:

adding the carbon nano tubes and the ball milling beads into the ball milling solvent, and performing ball milling operation to obtain primary slurry;

adding the binder into the primary slurry, and performing ball milling operation to obtain intermediate slurry;

and adding the metal powder into the intermediate slurry, and performing ball milling operation to obtain the carbon nanotube slurry.

6. The method of claim 4,

the metal powder is one of titanium powder or aluminum powder.

7. The method of claim 1,

forming a carbon nanotube layer on the surface of the conductive substrate by using the carbon nanotube slurry to form the carbon nanotube cathode, including:

printing the carbon nanotube paste on the surface of the conductive substrate using a screen printing technique to form the carbon nanotube cathode.

8. The method of claim 1,

after forming a carbon nanotube layer on the surface of the conductive substrate by using the carbon nanotube slurry to form the carbon nanotube cathode, the method further includes:

placing the carbon nanotube cathode in a vacuum environment with a first preset temperature for heating, and maintaining for a first preset time;

and raising the temperature of the vacuum environment to a second preset temperature, and maintaining for a second preset time to obtain the heated carbon nanotube cathode.

9. The method of claim 8,

the method further comprises the following steps:

and removing the carbide on the surface of the heated cathode of the carbon nano tube.

10. A carbon nanotube cathode, characterized in that the carbon nanotube cold cathode is prepared by the preparation method of claims 1 to 9.

11. An electronic device, characterized in that the electronic device comprises the carbon nanotube cathode of claim 10.

Technical Field

The present disclosure relates to field emission technologies, and in particular, to a method for manufacturing a carbon nanotube cathode, and an electronic device.

Background

Carbon Nanotubes (CNTs) have excellent electrochemical properties, extremely high aspect ratios, and excellent mechanical strength, and thus have been used as electron sources in Field Emission (FE) devices. As a field emission cold cathode material, it has low working voltage, high field emission current density and unique working stability, thus becoming the focus of research in the field of field emission.

In many applications of vacuum microwave equipment, not only is it required to be able to emit a high current density, but also a low deterioration rate of performance during long-term use is required. The carbon nanotube-based field emission device generally includes a substrate and carbon nanotubes coated or printed on or grown on the substrate, but the carbon nanotubes grown ex-situ on the substrate are not stably contacted with the substrate due to being coated by a slurry, so that the current stability and uniformity of the emitter are difficult to control.

In view of the above, it is desirable to provide a carbon nanotube field emission cathode and a method for manufacturing the same, which can provide a carbon nanotube field emission cathode with a large current surface density and uniform stability.

Disclosure of Invention

The application mainly provides a manufacturing method of a carbon nanotube cathode, the carbon nanotube cathode and electronic equipment, and can solve the problem of uneven emission current density caused by unstable contact between a carbon nanotube and a substrate in the prior art.

In order to solve the above technical problems, a first aspect of the present application provides a method for manufacturing a carbon nanotube cathode, the method comprising: providing a conductive substrate; carrying out surface treatment on the conductive substrate to form a concave structure on the surface of the conductive substrate; and forming a carbon nanotube layer on the surface of the conductive substrate by using the carbon nanotube slurry to form the carbon nanotube cathode.

Wherein, the surface treatment is carried out on the conductive substrate to form a concave structure on the surface of the conductive substrate, and the method comprises the following steps: cleaning the conductive substrate; and placing the conductive substrate after the cleaning operation in an alkaline solution to form a concave structure on the surface of the conductive substrate.

Wherein the cleaning the conductive substrate comprises: performing ultrasonic operation on the conductive substrate; cleaning the conductive substrate subjected to the ultrasonic operation by using ethanol; and drying the conductive substrate after the cleaning operation.

Wherein the method further comprises: adding carbon nanotubes, ball milling beads, a binder and metal powder into a ball milling solvent to perform ball milling operation on the carbon nanotubes to form the carbon nanotube slurry.

Adding carbon nanotubes, ball milling beads, a binder and metal powder into a ball milling solvent to perform ball milling operation on the carbon nanotubes to form the carbon nanotube slurry, wherein the step of adding the carbon nanotubes, the ball milling beads, the binder and the metal powder into the ball milling solvent comprises the following steps: adding the carbon nano tubes and the ball milling beads into the ball milling solvent, and performing ball milling operation to obtain primary slurry; adding the binder into the primary slurry, and performing ball milling operation to obtain intermediate slurry; and adding the metal powder into the intermediate slurry, and performing ball milling operation to obtain the carbon nanotube slurry.

Wherein the metal powder is one of titanium powder or aluminum powder.

Wherein the forming a carbon nanotube layer on the surface of the conductive substrate using the carbon nanotube slurry to form the carbon nanotube cathode comprises: printing the carbon nanotube paste on the surface of the conductive substrate using a screen printing technique to form the carbon nanotube cathode.

Wherein after forming a carbon nanotube layer on the surface of the conductive substrate using the carbon nanotube slurry to form the carbon nanotube cathode, the method further comprises: placing the carbon nanotube cathode in a vacuum environment with a first preset temperature for heating, and maintaining for a first preset time; and raising the temperature of the vacuum environment to a second preset temperature, and maintaining for a second preset time to obtain the heated carbon nanotube cathode.

Wherein the method further comprises: and removing the carbide on the surface of the heated cathode of the carbon nano tube.

In order to solve the above technical problems, a second aspect of the present application provides a carbon nanotube cathode, which is prepared by the method for manufacturing the carbon nanotube cathode according to the first aspect.

In order to solve the above technical problem, a third aspect of the present application provides an electronic device including the carbon nanotube cathode as provided in the first aspect described above.

The beneficial effect of this application is: be different from prior art's condition, this application carries out surface treatment to conductive substrate to form sunk structure on conductive substrate's surface, then utilize carbon nanotube thick liquids to form carbon nanotube layer on conductive substrate's surface, with the formation carbon nanotube negative pole, electrically conductive after the surface treatment can combine with carbon nanotube better basically, improves base plate and carbon nanotube's joint strength, and then effectively improves carbon nanotube's field emission current density and stability, and preparation technology is simple, easily operation, easily realization.

Drawings

FIG. 1 is a schematic block flow diagram of one embodiment of a method for fabricating a carbon nanotube cathode according to the present application;

FIG. 2 is a block diagram illustrating the flowchart of an embodiment of step S20 of the present application;

FIG. 3 is a schematic block diagram of an embodiment of the present application for drying and sintering a carbon nanotube cathode;

FIG. 4 is a schematic block flow diagram of another embodiment of a method of fabricating a carbon nanotube cathode according to the present application;

FIG. 5 is a block diagram illustrating the flowchart of step S60 according to an embodiment of the present application;

FIG. 6 is a schematic view of a field emission test of an embodiment of a carbon nanotube cold cathode;

FIG. 7 is a graph showing the results of field emission performance of carbon nanotube cold cathodes tested under DC voltage in accordance with the present application;

FIG. 8 is a graph showing the results of testing the field emission performance of the carbon nanotube cold cathode under AC voltage;

FIG. 9 shows the results of testing the field emission stability of the carbon nanotube cold cathode under AC voltage.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The terms "first" and "second" in this application are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features shown. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. Furthermore, the terms "comprising" and "having," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those skilled in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.

Referring to fig. 1, fig. 1 is a schematic flow chart of an embodiment of a method for manufacturing a carbon nanotube cathode according to the present application. The method for manufacturing the carbon nanotube cathode in this embodiment may include the following steps:

s10, providing a conductive substrate.

The conductive substrate may be a metal or alloy substrate. The conductive substrate is used for preparing and forming a carbon nano tube layer on the surface so as to obtain the carbon nano tube cathode.

And S20, performing surface treatment on the conductive substrate to form a concave structure on the surface of the conductive substrate.

The surface treatment operation of the conductive substrate in the step is to form a concave structure on the surface of the substrate, and the surface treatment is carried out on the surface of the substrate for forming the carbon nano tube layer in the step, so that a hollow nano net structure is formed on the surface of the substrate, the surface contact area of the conductive substrate is increased, and the bonding strength of the conductive substrate and the carbon nano tube layer is further enhanced.

The surface treatment operation in this step may be an alkali treatment operation on the conductive substrate. Referring to fig. 2, fig. 2 is a schematic block diagram illustrating a flow of step S20 according to an embodiment of the present application. The method specifically comprises the following steps:

s201, conducting cleaning operation on the conductive substrate.

The method comprises the steps of cleaning a provided conductive substrate, specifically, firstly carrying out ultrasonic operation on the conductive substrate to clean the conductive substrate by using ultrasonic waves, wherein the ultrasonic cleaning time can be 4-8 hours, after the ultrasonic cleaning is finished, cleaning the conductive substrate subjected to the ultrasonic operation by using ethanol, and then drying the conductive substrate subjected to the cleaning operation.

S202, the conductive substrate after the cleaning operation is placed in an alkaline solution to form a concave structure on the surface of the conductive substrate.

In the step, the conductive substrate after the cleaning operation can be subjected to alkali treatment by using alkali solution, so that the depression of the nano-mesh structure is formed on the surface of the substrate, the specific surface of the conductive substrate is increased, and the bonding strength of the conductive substrate and the carbon nano tube can be effectively improved.

Specifically, in this step, the conductive substrate may be placed in an alkali solution, and after standing at a preset temperature for a preset time, the conductive substrate may be taken out to complete alkali treatment of the substrate.

For example, the alkali solution is a 3M sodium hydroxide solution, in this step, the conductive substrate is placed in the 3M sodium hydroxide solution, and after standing for a predetermined time at a predetermined temperature, the conductive substrate is taken out, so that the conductive substrate after alkali treatment can be obtained.

Wherein the predetermined temperature may be 25 ℃ to 35 ℃, for example, the predetermined temperature is 28 ℃, 30 ℃, 32 ℃; the preset time period may be 22-26 hours, for example, the preset time period is 23 hours, 24 hours, 25 hours.

And S30, forming a carbon nanotube layer on the surface of the conductive substrate by using the carbon nanotube slurry to form a carbon nanotube cathode.

The carbon nanotube slurry can be coated or printed on the surface of the conductive substrate to form a carbon nanotube layer, thereby obtaining the carbon nanotube cathode.

In one embodiment, the carbon nanotube cathode is prepared by printing carbon nanotube paste on the surface of the conductive substrate by a screen printing technique. The silk screen printing refers to that a silk screen is used as a plate base, and a silk screen printing plate with pictures and texts is manufactured by a photosensitive plate making method.

Referring to fig. 3, after step S30, the carbon nanotube cathode may be dried and sintered in a vacuum environment, which includes the following steps:

s31, the carbon nanotube cathode is placed in a vacuum environment with a first predetermined temperature for heating and is maintained for a first predetermined time.

This step performs a drying operation on the carbon nanotube cathode. Wherein the first predetermined temperature may be 150 ℃ to 250 ℃, for example 180 ℃, 200 ℃, 220 ℃; the first predetermined time may be 1 to 3 hours, for example, 1.5 hours, 2 hours, 2.5 hours.

And S32, raising the temperature of the vacuum environment to a second preset temperature and maintaining the temperature for a second preset time to obtain the heated carbon nanotube cathode.

Step S31 is to heat the carbon nanotube cathode to a second preset temperature after drying the carbon nanotube cathode, so as to calcine and remove the glue from the carbon nanotube cathode. Wherein the heating rate is 2-5 deg.C/min, such as 2 deg.C/min, 3 deg.C/min, and 4 deg.C/min.

Wherein the second predetermined temperature may be 600 ℃ to 800 ℃, for example 650 ℃, 700 ℃, 750 ℃; the second predetermined time may be 1 to 3 hours, for example, 1.5 hours, 2 hours, 2.5 hours.

And S33, removing the carbide on the surface of the heated carbon nanotube cathode.

The carbide on the surface of the carbon nanotube cathode can be removed by sticking with 3M adhesive tape.

Thus, the preparation of the carbon nanotube cathode is completed.

The embodiment forms the hollow nano-net structure on the surface of the substrate by performing surface treatment on the substrate, increases the specific surface of the substrate, well improves the bonding strength of the carbon nanotube and the alloy substrate, and further improves the field emission current density and stability of the carbon nanotube.

Referring to fig. 4, fig. 4 is a schematic flow chart diagram of another embodiment of a method for fabricating a carbon nanotube cathode according to the present application. It should be noted that, if the result is substantially the same, the flow sequence shown in fig. 4 is not limited in this embodiment. The method for manufacturing the carbon nanotube cathode comprises the following steps:

s40, providing a conductive substrate.

The conductive substrate can be a substrate made of metal or alloy material, or an insulating substrate plated with a conductive metal layer or alloy layer on the surface, for example, a Ti6Al4V alloy substrate (Ti-6Al-4V is the nominal chemical composition expression method of titanium alloy mark TC4, and the composition of the titanium alloy TC4 material is Ti-6Al-4V, which belongs to (alpha + beta) type titanium alloy, and has good comprehensive mechanical properties and large specific strength). The conductive substrate is used for preparing and forming a carbon nano tube layer on the surface so as to obtain the carbon nano tube cathode.

And S50, performing surface treatment on the conductive substrate to form a concave structure on the surface of the conductive substrate.

The surface treatment operation of the conductive substrate in the step is to form a concave structure on the surface of the substrate, and the surface treatment is carried out on the surface of the substrate for forming the carbon nano tube layer in the step, so that a hollow nano net structure is formed on the surface of the substrate, the surface contact area of the conductive substrate is increased, and the bonding strength of the conductive substrate and the carbon nano tube layer is further enhanced.

The surface treatment operation in this step may be an alkali treatment operation on the conductive substrate. Specifically, reference may be made to step S201 in the previous embodiment, which is not described herein again.

And S60, adding the carbon nano tubes, the ball milling beads, the binder and the metal powder into a ball milling solvent to perform ball milling operation on the carbon nano tubes to form carbon nano tube slurry.

Wherein the particle size of the metal powder is 20 nm-50 μm. In the process of preparing the slurry by ball milling, the metal powder can cause mechanical damage to the carbon nano tube and increase the surface defects of the carbon nano tube, thereby increasing the emission sites of electrons, further reducing the work function of a carbon nano tube cathode system and improving the overall emission efficiency.

Wherein, the binder can be sodium carboxymethyl cellulose, and the ball milling solvent can be terpineol; alternatively, the binder may be polyvinylidene fluoride and the ball milling solvent may be N-methylpyrrolidone.

The metal powder is a metal powder having a low work function, and may be, for example, an aluminum powder or a titanium powder.

Referring to fig. 5, fig. 5 is a schematic block diagram illustrating a flow of step S60 according to an embodiment of the present application. It should be noted that, if the result is substantially the same, the flow sequence shown in fig. 5 is not limited in this embodiment. The preparation of the carbon nanotube slurry in this embodiment specifically includes the following steps:

and S61, adding the carbon nano tubes and the ball milling beads into a ball milling solvent, and performing ball milling operation to obtain primary slurry.

Adding the carbon nano tubes and the ball milling beads into a ball milling solvent, and performing ball milling operation for 2-4 hours to obtain primary slurry.

S62, adding a binder to the primary slurry, and performing a ball milling operation to obtain an intermediate slurry.

In the step, the binder is added into the primary slurry obtained in the step S61, and ball milling operation is performed for 3-5 hours to obtain intermediate slurry.

And S63, adding the metal powder into the intermediate slurry, and performing ball milling operation to obtain the carbon nanotube slurry.

In the step, metal powder is added into the intermediate slurry obtained in the step S62, and the ball milling operation is performed for 1-3 hours to obtain the carbon nanotube slurry. In the process of mechanical ball milling, the metal powder causes mechanical damage to the surface of the carbon nano tube, so that the surface defects of the carbon nano tube are increased, the emission sites of electrons are increased, and the work function is effectively reduced.

And S70, forming a carbon nanotube layer on the surface of the conductive substrate by using the carbon nanotube slurry to form a carbon nanotube cathode.

The carbon nanotube slurry can be coated or printed on the surface of the conductive substrate to form a carbon nanotube layer, thereby obtaining the carbon nanotube cathode.

In one embodiment, the carbon nanotube cathode is prepared by printing carbon nanotube paste on the surface of the conductive substrate by a screen printing technique.

After this step, the carbon nanotube cathode may be dried and sintered in a vacuum environment, and please refer to steps S31 to S33, which are not described herein again.

In the embodiment, on one hand, the conductive substrate is subjected to alkali treatment, a concave structure is formed on the surface of the conductive substrate, the substrate with a larger specific surface is obtained, and the bonding strength between the conductive substrate and the carbon nano tube is effectively improved; on the other hand, in the process of preparing the slurry, the metal powder is added to perform the ball milling operation together with the carbon nanotube to cause mechanical damage to the surface of the carbon nanotube, so that the surface defects of the carbon nanotube are increased, the emission sites of electrons are increased, and the work function is effectively reduced. Therefore, the embodiment can effectively improve the field emission current density and stability of the carbon nanotube, and the preparation process is simple and easy to operate.

The steps (1) to (7) are steps of a method of preparing a carbon nanotube cathode according to a specific embodiment of this embodiment, and include:

(1) providing a Ti6Al4V alloy substrate;

(2) carrying out ultrasonic operation on the Ti6Al4V alloy substrate for 6 hours, cleaning with ethanol, and drying;

(3) placing the dried Ti6Al4V alloy substrate in a 10M NaOH solution, and standing for 24h at the temperature of 30 ℃ to finish the surface treatment of the Ti6Al4V alloy substrate;

(4) preparing carbon nano tube slurry;

comprises the following steps of a to c:

a. ball-milling 0.1-0.5 g of carbon nanotubes, ZrC ball-milled beads and 2-6 mL of terpineol for 3 hours to obtain primary slurry;

b. adding 0.05-0.2 g of sodium carboxymethylcellulose into the primary slurry, and performing ball milling for 4 hours to obtain intermediate slurry;

c. and adding 0.05-0.2 g of titanium powder into the intermediate slurry, and performing ball milling for 2 hours to obtain carbon nanotube slurry.

(5) Printing the carbon nanotube slurry on a Ti6Al4V alloy substrate by a screen printing method to obtain a carbon nanotube cathode;

(6) drying the carbon nanotube cathode in vacuum at 200 ℃ for 2 hours, heating to 700 ℃ at a heating rate of 3 ℃/min, and preserving heat for 2 hours;

(7) and (3) removing carbide on the surface of the carbon nanotube cathode by using a 3M adhesive tape to complete the preparation of the carbon nanotube cathode.

Referring to fig. 6 to 9, fig. 6 is a schematic view of a field emission test of the carbon nanotube cold cathode of the present embodiment, fig. 7 is a schematic view of a field emission performance result of the carbon nanotube cold cathode of the present embodiment under a direct current voltage, fig. 8 is a schematic view of a field emission performance result of the carbon nanotube cold cathode of the present embodiment under an alternating current voltage, and fig. 9 is a schematic view of a field emission stability result of the carbon nanotube cold cathode of the present embodiment under an alternating current voltage, wherein D1 and D2 in fig. 7 and 8 are both experimental results of a control group.

The experimental results show that: the carbon nanotube cold cathode prepared by the embodiment can obtain an opening electric field of 0.79V/mum under the drive of direct current, and can obtain a current density of 85.13mA/cm2 under the electric field strength of 2.38V/mum; can show a current density of 1.226A/cm2 at an electric field strength of 6.1V/mum under the drive of alternating current; and the current density still reached 0.4A/cm2 after driving for 15 hours at an electric field strength of 4.0V/mum. Therefore, the carbon nanotube prepared by the method of the embodiment has larger and more stable field emission current density.

The application also provides a carbon nanotube cathode, which is prepared by the preparation method of the carbon nanotube cathode, and details on the preparation method are not repeated here, and the carbon nanotube cathode prepared by the method enhances the bonding strength of the substrate and the carbon nanotube, so that the field emission current density is higher and more stable.

The present application also provides an electronic device, such as a field emission flat display device or a vacuum electron source, comprising the carbon nanotube cathode provided in the above embodiments, which also has the characteristics of greater and more stable field emission current density due to the improvement of the preparation process in the above embodiments.

The above description is only an example of the present application and is not intended to limit the scope of the present application, and all modifications of equivalent structures and equivalent processes, which are made by the contents of the specification and the drawings, or which are directly or indirectly applied to other related technical fields, are intended to be included within the scope of the present application.