Preparation method of high-thermal-conductivity composite material based on flexible graphite paper double-sided growth and vertical arrangement of carbon nanotube arrays

Abstract

The invention relates to a preparation method of a high-thermal-conductivity composite material based on a flexible graphite paper double-sided growth vertically-arranged carbon nanotube array, which comprises the following two steps: high-temperature calcination and chemical vapor deposition: firstly, mixing a certain amount of polycarbosilane with a xylene solution to obtain a polycarbosilane solution; then spin coating is carried out on the two faces of the graphite paper subjected to heat treatment, a polycarbosilane coating is obtained, the polycarbosilane coating is cracked at the high temperature, and the graphite paper containing the silicon carbide coating is obtained. Then chemical vapor deposition is carried out on the two faces of the obtained graphite paper containing the silicon carbide coating to grow regularly-arranged carbon nano tube arrays, the obtained composite material is of an obvious three-dimensional layered structure, the interface bonding force between carbon nano tubes and the surface of the graphite paper is remarkably enhanced, and the composite material has excellent directional heat conduction performance and bending strength; a certain effect is achieved on the practical application of the efficient heat management material.

Description

Technical Field

[0001] The invention relates to a method for preparing a high thermal conductivity composite material based on double-sided growth of vertically arranged carbon nanotube arrays on flexible graphite paper, belonging to the field of composite materials. Background Art

[0002] Thermal management system is a thermal management system based on thermodynamics and heat transfer process, which is widely used in the fields of national economy and national defense. It controls the dissipation, storage and conversion of heat in equipment and device systems. With the rapid development of science and technology, electronic components are constantly developing in the direction of miniaturization and high frequency, and multifunctional integrated circuits with ultra-high integration are constantly being developed and applied, which makes the power consumption of integrated circuits increase sharply and accumulates a lot of heat in a short time, which seriously restricts the service life of the device. Relevant research shows that the design and development of efficient thermal management materials is the key to improving thermal management systems, which not only realizes the thermal management function of equipment and device systems, but also protects equipment and devices from overheating damage.

[0003] High-efficiency thermal management materials can be divided into metal-based, ceramic-based, polymer-based and nano-carbon-based thermal conductive composite materials according to the different composite materials. Among these four high thermal conductivity composite materials, nano-carbon-based composite materials have attracted much attention due to their low density, high thermal conductivity, low thermal expansion coefficient, high mechanical strength and other advantages. Many different nano-carbon-based materials, including graphene, nanobelts, carbon nanotubes, etc., have been explored to construct three-dimensional high thermal conductivity carbon-based composite materials by arranging and assembling low-dimensional carbon materials in a directional manner. Graphite materials and their derivatives such as graphene and carbon nanotubes are considered to be one of the most suitable candidate materials for assembling three-dimensional nano-carbon-based composite materials due to their unique geometric shape, low density, and excellent thermal transmission and mechanical properties.

[0004] Three-dimensional nanocarbon-based composite materials have attracted widespread attention due to their unique three-dimensional structure and advantages such as multi-directional efficient heat conduction. Their characteristics and structural advantages also make them very suitable as efficient thermal management materials. Among them, two-dimensional graphene nanosheets have extremely high in-plane thermal conductivity, which can reach 3000-5000W / (m·k), while one-dimensional carbon nanotubes have extremely high axial thermal conductivity. Therefore, it has become a common method to prepare macroscopic ordered high thermal conductivity composite materials by combining low-dimensional graphene carbon / carbon nanotubes. For example, vertically arranged carbon nanotubes are grown on graphene films, and graphene thermal conductive films are filled with carbon nanotubes as fillers. However, macroscopic nanocarbon-based materials have defects such as orientation, interface, and crystallinity, which seriously restrict their directional thermal conduction performance. It is necessary to adopt effective strategies to reduce defects and optimize their microstructures in order to construct advanced macroscopic thermal management materials.

[0005] Therefore, it is of great significance to design and prepare a three-dimensional nanocarbon-based composite material with the advantages of high thermal conductivity, low density, strong interface bonding, and high mechanical strength. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing a high thermal conductivity composite material based on double-sided growth of vertically arranged carbon nanotube arrays on flexible graphite paper. The vertically arranged carbon nanotube arrays form a strong interface bond with the surface of the graphite paper through carbon-silicon bonds, and are cross-linked and welded together, which effectively avoids the loosening and falling off of the carbon nanotube array on the graphite paper, significantly improves the interface bonding force between the two, and effectively enhances the directional thermal conductivity and mechanical properties of the composite material.

[0007] The present invention adopts the following technical solution:

[0008] The present invention relates to a method for preparing a high thermal conductivity composite material based on double-sided growth of vertically aligned carbon nanotube arrays on flexible graphite paper, the steps of which are as follows:

[0009] 1) Preparation of graphite paper containing silicon carbide coating: Mix a certain amount of polycarbosilane with a xylene solution, and ultrasonically disperse it for a certain period of time to obtain a polycarbosilane solution. Cut the purchased commercial graphite paper into rectangular blocks of 4cm×4cm in size, clamp them with two pieces of quartz glass, put them in the center of a tube furnace, and heat them to 700°C in an argon / hydrogen mixed atmosphere for thermal reduction treatment. Use a spin coater to spin-coat a thin layer of polycarbosilane coating on both sides of the heat-treated graphite paper, and then calcine the graphite paper containing polycarbosilane coating at 1000°C in an argon / hydrogen flow to obtain graphite paper containing silicon carbide coating on both sides;

[0010] 2) Preparation of high thermal conductivity composite material based on graphite paper with vertically aligned carbon nanotubes grown on both sides: Place the graphite paper with silicon carbide coating described in step 1) in a tube furnace. Prepare a catalyst solution of a certain concentration using ferrocene as a catalyst and xylene as a solvent, and heat it to 860°C under argon / hydrogen protection. Then inject the catalyst solution into the tube at a rate of 20 ml / h through a syringe and keep it warm for a certain period of time to obtain a composite material of graphite paper / double-sided vertically aligned carbon nanotubes.

[0011] Preferably, the concentration of polycarbosilane in the polycarbosilane solution in step 1) is 0.05 g / ml, 0.1 g / ml, or 0.15 g / ml.

[0012] Preferably, the ultrasonic dispersion time in step 1) is 30-60 min.

[0013] Preferably, the rotation speed of the spin coating in step 1) is 4000-4500 r / min.

[0014] Preferably, in step 2), the mass ratio of ferrocene to xylene in the catalyst solution is 1:5, 1:10, or 1:15.

[0015] Preferably, the heating rate in step 2) is 8-15°C / min.

[0016] Preferably, in step 2), the holding time at 860° C. is 15 to 30 minutes.

[0017] The present invention prepares a composite material of vertically arranged carbon nanotubes grown on both sides of flexible graphite paper by a two-step method of high-temperature calcination and chemical vapor deposition. The obtained composite material has a distinct three-dimensional layered structure, and the vertically arranged carbon nanotube arrays are evenly distributed on both sides of the graphite paper, which significantly improves the cross-plane thermal conductivity and bending strength of the composite material, and plays an important role in its practical application in high-efficiency thermal management materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a scanning electron microscope image of a cross section of a high thermal conductivity composite material based on vertically aligned carbon nanotubes grown on both sides of flexible graphite paper at a magnification of 200 μm;

[0019] Figure 2 This is a scanning diagram of the X-ray energy spectrum analysis at the cross section of a high thermal conductivity composite material based on double-sided growth of vertically aligned carbon nanotubes on flexible graphite paper; DETAILED DESCRIPTION

[0020] Six embodiments of the present invention are given below to further illustrate the present invention, but not to limit the scope of the present invention.

[0021] Example 1

[0022] 1) Preparation of graphite paper containing silicon carbide coating: 0.05 mg / mL polycarbosilane solution was ultrasonically dispersed for 30 min, and then polycarbosilane was spin-coated on both sides of the graphite paper using a spin coater at a spin coating rate of 4000 r / min for 40 s. The graphite paper containing polycarbosilane coating was placed in a tubular furnace and calcined to obtain graphite paper containing silicon carbide coating on both sides;

[0023] 2) Preparation of a high thermal conductivity composite material based on vertically aligned carbon nanotubes grown on both sides of graphite paper: Place the graphite paper containing silicon carbide coating described in step 1) into a tubular furnace, raise the temperature to 860°C at 8°C / min in an argon / hydrogen protection environment, inject a catalyst solution with a mass ratio of ferrocene to xylene of 1:5 at a rate of 20 ml / h, and keep the temperature for 15 mm to obtain a composite material based on vertically aligned carbon nanotubes grown on both sides of graphite paper.

[0024] Example 2

[0025] 1) Preparation of graphite paper containing silicon carbide coating: 0.1 mg / mL polycarbosilane solution was ultrasonically dispersed for 40 min, and then polycarbosilane was spin-coated on both sides of the graphite paper using a spin coater at a spin coating rate of 4100 r / min for 40 s. The graphite paper containing polycarbosilane coating was placed in a tubular furnace and calcined to obtain graphite paper containing silicon carbide coating on both sides;

[0026] 2) Preparation of a high thermal conductivity composite material based on vertically aligned carbon nanotubes grown on both sides of graphite paper: Place the graphite paper containing silicon carbide coating described in step 1) into a tubular furnace, heat it to 860°C at 10°C / min in an argon / hydrogen protection environment, inject a catalyst solution with a mass ratio of ferrocene to xylene of 1:10 at a rate of 20 ml / h, and keep it warm for 20 minutes to obtain a composite material based on vertically aligned carbon nanotubes grown on both sides of graphite paper.

[0027] Example 3

[0028] 1) Preparation of graphite paper containing silicon carbide coating: 0.15 mg / mL polycarbosilane solution was ultrasonically dispersed for 60 min, and then polycarbosilane was spin-coated on both sides of the graphite paper using a spin coater at a spin coating rate of 4200 r / min for 40 s. The graphite paper containing polycarbosilane coating was placed in a tubular furnace and calcined to obtain graphite paper containing silicon carbide coating on both sides;

[0029] 2) Preparation of a high thermal conductivity composite material based on vertically aligned carbon nanotubes grown on both sides of graphite paper: Place the graphite paper containing silicon carbide coating described in step 1) into a tubular furnace, heat it to 860°C at 15°C / min in an argon / hydrogen protection environment, inject a catalyst solution with a mass ratio of ferrocene to xylene of 1:15 at a rate of 20 ml / h, and keep it warm for 30 minutes to obtain a composite material based on vertically aligned carbon nanotubes grown on both sides of graphite paper.

[0030] Example 4

[0031] 1) Preparation of graphite paper containing silicon carbide coating: 0.15 mg / mL polycarbosilane solution was ultrasonically dispersed for 30 min, and then polycarbosilane was spin-coated on both sides of the graphite paper using a spin coater at a spin coating rate of 4300 r / min for 40 s. The graphite paper containing polycarbosilane coating was placed in a tubular furnace and calcined to obtain graphite paper containing silicon carbide coating on both sides;

[0032] 2) Preparation of a high thermal conductivity composite material based on vertically aligned carbon nanotubes grown on both sides of graphite paper: Place the graphite paper containing silicon carbide coating described in step 1) into a tubular furnace, raise the temperature to 860°C at 10°C / min in an argon / hydrogen protection environment, inject a catalyst solution with a mass ratio of ferrocene to xylene of 1:5 at a rate of 20 ml / h, and keep the temperature for 20 minutes to obtain a composite material based on vertically aligned carbon nanotubes grown on both sides of graphite paper.

[0033] Example 5

[0034] 1) Preparation of graphite paper containing silicon carbide coating: 0.15 mg / mL polycarbosilane solution was ultrasonically dispersed for 30 min, and then polycarbosilane was spin-coated on both sides of the graphite paper using a spin coater at a spin coating rate of 4500 r / min for 40 s. The graphite paper containing polycarbosilane coating was placed in a tubular furnace and calcined to obtain graphite paper containing silicon carbide coating on both sides;

[0035] 2) Preparation of a high thermal conductivity composite material based on vertically aligned carbon nanotubes grown on both sides of graphite paper: Place the graphite paper containing silicon carbide coating described in step 1) into a tubular furnace, raise the temperature to 860°C at 10°C / min in an argon / hydrogen protection environment, inject a catalyst solution with a mass ratio of ferrocene to xylene of 1:10 at a rate of 20 ml / h, and keep the temperature for 30 minutes to obtain a composite material based on vertically aligned carbon nanotubes grown on both sides of graphite paper.

[0036] Example 6

[0037] 1) Preparation of graphite paper containing silicon carbide coating: 0.15 mg / mL polycarbosilane solution was ultrasonically dispersed for 30 min, and then polycarbosilane was spin-coated on both sides of the graphite paper using a spin coater at a spin coating rate of 4500 r / min for 40 s. The graphite paper containing polycarbosilane coating was placed in a tubular furnace and calcined to obtain graphite paper containing silicon carbide coating on both sides;

[0038] 2) Preparation of a high thermal conductivity composite material based on vertically aligned carbon nanotubes grown on both sides of graphite paper: Place the graphite paper containing silicon carbide coating described in step 1) into a tubular furnace, heat it to 860°C at 10°C / min in an argon / hydrogen protection environment, inject a catalyst solution with a mass ratio of ferrocene to xylene of 1:15 at a rate of 20 ml / h, and keep it warm for 30 minutes to obtain a composite material based on vertically aligned carbon nanotubes grown on both sides of graphite paper.

Claims

1. A method for preparing a high thermal conductivity composite material based on double-sided growth of vertically aligned carbon nanotube arrays on flexible graphite paper, characterized in that The preparation steps are as follows: 1) Preparation of graphite paper containing silicon carbide coating: Mix a certain amount of polycarbosilane with a xylene solution, and ultrasonically disperse it for a certain period of time to obtain a polycarbosilane solution. Cut the purchased commercial graphite paper into rectangular blocks of 4cm×4cm in size, clamp them with two pieces of quartz glass, put them in the center of a tube furnace, and heat them to 700°C in an argon / hydrogen mixed atmosphere for thermal reduction treatment. Use a spin coater to spin-coat a thin layer of polycarbosilane coating on both sides of the heat-treated graphite paper, and then calcine the graphite paper containing polycarbosilane coating at 1000°C in an argon / hydrogen flow to obtain graphite paper containing silicon carbide coating on both sides; 2) Preparation of composite materials based on graphite paper with vertically aligned carbon nanotubes grown on both sides: The graphite paper containing silicon carbide coating described in step 1) is placed in a tube furnace. Ferrocene is used as a catalyst and xylene is used as a solvent to prepare a catalyst solution of a certain concentration, and the catalyst solution is injected into the tube at a rate of 20 ml / h through a syringe under an argon / hydrogen protection environment after heating to 860°C, and the temperature is kept for a certain period of time to obtain a composite material of graphite paper / double-sided vertically aligned carbon nanotubes.

2. The preparation method according to claim 1, characterized in that The concentration of polycarbosilane in the polycarbosilane solution in step 1) is 0.05 g / ml, 0.1 g / ml, and 0.15 g / ml.

3. The preparation method according to claim 1, characterized in that The ultrasonic dispersion time in step 1) is 30-60 min.

4. The preparation method according to claim 1, characterized in that The rotation speed of the spin coating in step 1) is 4000-4500 r / min.

5. The preparation method according to claim 1, characterized in that Step 2) The mass ratio of ferrocene to xylene in the catalyst solution is 1:5, 1:10, and 1:

15.

6. The preparation method according to claim 1, characterized in that Step 2) heating rate 8-15°C / min.

7. The preparation method according to claim 1, characterized in that Step 2) The holding time at 860° C. is 15 to 30 minutes.

8. According to the preparation method described in claim 1, a high thermal conductivity composite material based on vertically arranged carbon nanotube arrays grown on both sides of flexible graphite paper is obtained, and the obtained composite material has a distinct three-dimensional layered structure, and the vertically arranged carbon nanotube arrays are evenly distributed on both sides of the graphite paper, which significantly improves the cross-plane thermal conductivity and bending strength of the composite material, and plays a certain role in its practical application in high-efficiency thermal management materials.

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