Carbon nanotube / glassy carbon composite thin film, and preparation method and application thereof

Abstract

This invention proposes a carbon nanotube / glassy carbon composite film, its preparation method, and its applications. The method utilizes an alcohol spraying process to densify the carbon nanotube film. Subsequently, glassy carbon is loaded onto the carbon nanotube film using chemical vapor deposition, reducing the contact resistance between carbon nanotubes and hindering the relative movement between single-walled carbon nanotubes, thus obtaining the carbon nanotube / glassy carbon composite film. This invention employs a two-step densification method—alcohol spraying and glassy carbon loading—to give the carbon nanotube / glassy carbon composite film high strength, electromagnetic shielding effectiveness, and electrothermal properties.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials technology, and in particular to a carbon nanotube / glass carbon composite film, its preparation method, and its application. Background Technology

[0002] With the continuous development of intelligent, portable, and wearable electronic devices, the demand for high-performance electromagnetic shielding materials is becoming increasingly urgent. These materials not only need to possess excellent electromagnetic shielding performance, but also must meet various functional and performance requirements to adapt to different application scenarios. Traditional metallic electromagnetic shielding materials are limited by their high density, poor flexibility, low corrosion resistance, and inefficient thermal conversion performance, and are no longer suitable for the diverse needs of modern electronic devices.

[0003] In the current context, carbon-based materials, including carbon nanotubes, graphene, and carbon nanofibers, are leading a new trend in the field of electromagnetic shielding materials. These materials, with their superior properties such as high strength, excellent conductivity, outstanding corrosion resistance, and lightweight, are widely regarded as ideal alternatives to traditional metals. However, the requirements for high-performance electromagnetic shielding materials go beyond shielding performance; they also include multiple standards such as mechanical strength, flexibility, reliability, wear resistance, and durability to adapt to the diverse application scenarios of modern electronic devices. Notably, the normal operation of electronic devices within a specific temperature range is crucial for many applications. Therefore, integrating Joule heating properties into electromagnetic shielding materials has become an indispensable trend. This functional integration allows the material to generate localized heating by controlling the current, thereby effectively managing the temperature of the device. The importance of Joule heating properties is particularly significant in specific applications such as anti-icing, de-icing, and temperature sensors.

[0004] In summary, high-performance electromagnetic shielding materials have become a key driving force in the evolution of electronic devices. Meanwhile, the superior performance and versatility of carbon-based materials have made them a highly sought-after material choice to meet the diverse needs of modern electronic devices.

[0005] Patent document CN112176313 A discloses a glassy carbon / carbon nanotube thin film composite material and its preparation method and application. Glassy carbon is directly deposited on the carbon nanotube thin film by vapor phase chemical deposition to obtain the glassy carbon / carbon nanotube thin film composite material. The tensile strength of this material is 80-90 MPa, and there is a problem that the mechanical strength needs to be further improved. Moreover, the direct deposition of glassy carbon on the surface of the carbon nanotube thin film is also prone to causing the carbon nanotube thin film to crack, resulting in the inability to effectively deposit glassy carbon. Summary of the Invention

[0006] This invention proposes a carbon nanotube / glass carbon composite film, its preparation method, and its application. Alcohol spraying is used to improve the density of the carbon nanotube film, increase the contact between carbon nanotubes, hinder their relative movement, and reduce the contact resistance. Finally, glass carbon is loaded onto the carbon nanotubes using chemical vapor deposition to form an interconnected welded network. This welded network further hinders the relative movement between carbon nanotubes, thereby improving the mechanical properties of the carbon nanotube film.

[0007] The technical solution of this invention is achieved as follows: a method for preparing a carbon nanotube / glassy carbon composite film, comprising the following steps:

[0008] (1) A carbon nanotube film is formed by spraying it with alcohol to create a dense carbon nanotube film.

[0009] (2) Glassy carbon is loaded onto a densified carbon nanotube film by chemical vapor deposition to obtain a carbon nanotube / glassy carbon composite film.

[0010] Furthermore, in step (1), the alcohol spraying method is as follows: the alcohol spraying flow rate is 3 mL / min to 10 mL / min, and the spraying time is 1 min to 3 min. The morphology of carbon nanotubes in the internal structure of the densified carbon nanotube film will be different depending on the nozzle flow rate and spraying time.

[0011] A dense carbon nanotube film is formed by spraying carbon nanotube film with alcohol. The alcohol spraying is carried out by using a sprayer to increase the contact between carbon nanotubes and obtain a dense carbon nanotube film.

[0012] Further, in step (2), the method of loading glassy carbon onto the densified carbon nanotube film by chemical vapor deposition is as follows: ferrocene and 1,2-dichlorobenzene are used as carbon sources, hydrogen-argon mixture is used as carrier gas, reaction temperature is 900℃, deposition time is 1-3h, and carbon nanotube / glassy carbon composite film is obtained.

[0013] Furthermore, in step (1), the carbon nanotube film is prepared by chemical vapor deposition.

[0014] Further, in step (1), the carbon nanotube film is prepared as follows: using ferrocene, sublimed sulfur and xylene as carbon sources, under a hydrogen-argon mixed gas atmosphere, the reaction temperature is 1200℃ to obtain a carbon nanotube film.

[0015] A carbon nanotube / glassy carbon composite film is prepared using the aforementioned preparation method.

[0016] Furthermore, the carbon nanotube / glass carbon composite film comprises a densified carbon nanotube film with glass carbon loaded on its surface, forming an interconnected welded network.

[0017] Application of carbon nanotube / glass carbon composite films in electromagnetic shielding.

[0018] The beneficial effects of this invention are:

[0019] Carbon nanotube films contain extremely long carbon nanotubes, reaching lengths of tens of centimeters. These nanotubes form an interwoven network structure with strong interactions between them. However, the films are still prone to breakage during glassy carbon loading. To address this issue, this invention utilizes an alcohol spraying method to shrink the carbon nanotube film in its thickness direction, increasing the interactions between the nanotubes, reducing their contact resistance, and resulting in a denser carbon nanotube film that prevents breakage during subsequent glassy carbon loading. Furthermore, chemical vapor deposition is used to load glassy carbon onto the carbon nanotubes, welding adjacent nanotubes to form a welded network. This network hinders relative movement between the nanotubes, significantly improving the mechanical strength, electromagnetic shielding, and electrothermal properties of the carbon nanotube fibers. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is an electron microscope image of the carbon nanotube / glassy carbon composite film of the present invention;

[0022] Figure 2 This is a mechanical curve of the carbon nanotube / glass carbon composite film of the present invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1

[0025] A method for preparing a carbon nanotube / glassy carbon composite film includes the following steps:

[0026] (1) A carbon nanotube film is formed by spraying it with alcohol to create a dense carbon nanotube film.

[0027] Continuous carbon nanotube thin films were prepared using chemical vapor deposition, as detailed below:

[0028] Ferrocene and sublimed sulfur were used as catalysts and dispersed in xylene at concentrations of 50 mg / mL and 1 mg / mL, respectively, to prepare carbon sources. 10 mL of carbon source was placed upstream of the gas flow and slowly pushed into the tube furnace at a rate of 360 μL / h using a precision injection pump. Under a hydrogen-argon mixed gas atmosphere with a hydrogen concentration of 20%, the gas flow rate was set to 2000 sccm, the reaction zone temperature was set to 1200℃, and carbon nanotube films were continuously grown and collected for 3 h to obtain a uniform carbon nanotube film with a thickness of 3 mm.

[0029] A 3 mm thick carbon nanotube film was fixed along its length and width. Alcohol was sprayed evenly onto the carbon nanotube film using a sprayer at a flow rate of 5 mL / min for 3 min, causing it to shrink in the thickness direction and resulting in a denser carbon nanotube film. At this point, the fracture stress of the carbon nanotube film was 30 MPa.

[0030] (2) Glassy carbon is loaded onto a densified carbon nanotube thin film by chemical vapor deposition, as follows:

[0031] Ferrocene was used as a catalyst, and a carbon source was prepared by dispersing it in 1,2-dichlorobenzene at a concentration of 60 mg / mL. The densified carbon nanotube film was placed in the reaction zone of chemical vapor deposition. 30 mL of carbon source was placed upstream of the gas, and the carbon source was slowly pushed into the tube furnace at a rate of 10 mL / h using a precision injection pump. A hydrogen-argon mixture with a hydrogen concentration of 10% was used as the carrier gas, and the gas flow rate was set to 3000 sccm. The carbon source with catalyst was introduced into the chemical vapor deposition reaction zone at a temperature of 900℃ and deposited for 3 h to obtain a carbon nanotube / glassy carbon composite film.

[0032] The conductivity of the carbon nanotube / glass carbon composite film prepared in Example 1 was tested using a four-probe testing technique, and the thickness of the film was measured using a scanning electron microscope. The conductivity of the composite film was calculated to be 2000 S / cm.

[0033] The carbon nanotube / glassy carbon composite film prepared in Example 1 was cut into sections with a length of 2 cm and a width of 0.5 cm. Both ends of the film were fixed to the fixed clamp and the moving clamp of the stretching machine, respectively. The length of the composite film exposed between the clamps was 1 cm. The stretching speed was 0.5 mm / min, and the elongation and stress of the carbon nanotube and glassy carbon composite film were recorded simultaneously until the film broke. The thickness of the carbon nanotube and glassy carbon composite film was tested using a scanning electron microscope, and the film strength was calculated to be 500 MPa.

[0034] The carbon nanotube / glassy carbon composite film prepared in Example 1 was cut with a length and width of 22.86±0.01mm×10.16±0.01mm. Its electromagnetic parameters were tested using a vector network analyzer, and the electromagnetic shielding effectiveness of the 7μm thick carbon nanotube and glassy carbon composite film was calculated to be 70dB.

[0035] The carbon nanotube / glass carbon composite film prepared in Example 1 was cut into sections with a length and width of 1cm × 2cm. The two ends of the film were connected to silver wire electrodes through silver paste. A Keithley 2400 was used to provide DC voltage, which can reach 200°C at a voltage of 3V.

[0036] Example 2

[0037] This embodiment is basically the same as Embodiment 1, except that the alcohol spraying flow rate is 3 mL / min and the spraying time is 3 min.

[0038] Example 3

[0039] This embodiment is basically the same as embodiment 1, except that the alcohol spraying flow rate is 10 mL / min and the spraying time is 1 min.

[0040] Comparative Example 1

[0041] This embodiment is basically the same as embodiment 1, except that: in step (1), the carbon nanotube film with a thickness of 3 mm is not densified with alcohol and directly enters step (2) and is placed in the reaction zone of chemical vapor deposition. During the glass carbon deposition process, the carbon nanotube film is easily damaged, causing the glass carbon to not be loaded onto the carbon nanotubes, resulting in poor mechanical strength.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A carbon nanotube / glassy carbon composite film, characterized in that, The carbon nanotube / glass carbon composite film includes a densified carbon nanotube film with glass carbon loaded on it, forming an interconnected welding network. The carbon nanotube / glass carbon composite film is used in electromagnetic shielding; The method for preparing the carbon nanotube / glassy carbon composite film includes the following steps: (1) A carbon nanotube film with a thickness of 3 mm is fixed in the length and width directions, and the carbon nanotube film is formed into a dense carbon nanotube film by spraying with alcohol. (2) Glassy carbon was loaded onto a densified carbon nanotube film by chemical vapor deposition to obtain a carbon nanotube / glassy carbon composite film; The tensile strength of the carbon nanotube / glass carbon composite film is 500 MPa; The electromagnetic shielding effectiveness of a 7μm thick carbon nanotube / glass carbon composite film is 70 dB. The two ends of the carbon nanotube / glass carbon composite film are connected to silver wire electrodes through silver paste, and the temperature reaches 200 °C at a voltage of 3V.

2. The method for preparing a carbon nanotube / glassy carbon composite film according to claim 1, characterized in that, In step (1), the alcohol spraying method is as follows: the alcohol spraying flow rate is 3 mL / min ~ 10 mL / min, and the spraying time is 1 min ~ 3 min.

3. The method for preparing a carbon nanotube / glassy carbon composite film according to claim 1, characterized in that, In step (1), the carbon nanotube film is prepared by chemical vapor deposition.

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