Metal-based carbon nanotube array composite heat dissipation material and preparation method thereof

Abstract

The invention discloses a metal-based carbon nanotube array composite heat dissipation material and a preparation method thereof, the surface of a metal sheet is coated with a polycarbosilane solution, the polycarbosilane solution is converted into silicon carbide through heat treatment, and then a carbon nanotube array is grown on the surface of a silicon carbide loading layer through a chemical vapor deposition method. The orientation direction of the obtained carbon nanotubes is perpendicular to the plane direction of the metal sheet, the carbon nanotubes are uniformly and compactly distributed on the surface of the metal sheet, the carbon nanotube array and the metal substrate are stably connected through a high-heat-conductivity silicon carbide layer, and heat from the metal substrate is rapidly diffused to the external environment in a heat conduction and heat radiation mode. Aiming at insufficient heat convection of a closed space and a vacuum system, the heat dissipation capability is superior to that of a traditional metal heat dissipation material.

Description

Technical Field

[0001] The invention relates to a carbon nanotube array / metal composite material with high-efficiency heat dissipation performance, belonging to the field of thermal conductive composite materials. Background Art

[0002] With the rapid development of the electronic information industry, high-density integration of electronic components and efficient heat dissipation have become key technologies that limit the performance improvement of electronic products. Statistics show that for every 2°C increase in the temperature of electronic components, the reliability will decrease by 10%, and excessively high temperatures may also bring safety hazards. At present, the heat generated by the electronic component system is mainly conducted to the metal heat dissipation structure with a large specific surface area through thermal interface materials to achieve directional and rapid diffusion to the outside. Generally, thermal interface materials are considered to be the bottleneck of heat transfer, but after years of development, their thermal conductivity has been significantly improved. For example, the thermal conductivity of the liquid metal thermal interface material disclosed in patent CN107053786B can reach 20 to 80W / mK, which is much higher than commercially available thermal interface materials, such as thermal grease, thermal silver glue, and phase change thermal conductive materials (thermal conductivity coefficients are usually no more than 7W / mK). The metal heat dissipation structure with a large specific surface area has gradually become a barrier to heat transfer. Metal heat dissipation is mainly achieved through three methods: heat conduction, heat convection, and heat radiation. As electronic component systems become further miniaturized and denser, it will be difficult to conduct heat away by forced convection. Heat conduction is limited by the low thermal conductivity of air. Therefore, enhancing metal thermal radiation is the preferred option.

[0003] Since the discovery of carbon nanotubes in 1991, their unique mechanical, electrical, thermal and other properties and unique quasi-one-dimensional tubular molecular structure have made them have many potential applications in future high-tech fields such as nanoelectronic devices and hydrogen storage fuel cells. Carbon nanotubes have good heat transfer performance, and their axial thermal conductivity can reach 6000W / (mK), which is one of the materials with the highest thermal conductivity. Therefore, carbon nanotubes are widely used to prepare thermally conductive composite materials. In addition, carbon nanotube arrays with regular orientation are the materials with the highest thermal emissivity known so far. They transmit heat from the substrate to the surrounding environment through infrared thermal radiation. Applying them to metal heat dissipation structures can significantly enhance the comprehensive heat dissipation performance.

[0004] In order to enhance the radiation heat dissipation capacity of metals, a carbon nanotube radiation layer can be introduced on the metal surface. At present, similar patents have been authorized or disclosed. Invention patents with authorization numbers CN203554877U and CN206014744U disclose the technology of introducing a carbon nanotube radiation layer on the metal surface, but the carbon nanotube layer is not an array-oriented structure, but a randomly distributed structure, and has a weak heat radiation capacity. In addition, the use of a polymer layer to bond the carbon nanotube layer to the metal substrate will cause discontinuous heat transfer and reduce the overall heat dissipation performance. Therefore, connecting the carbon nanotube array with high thermal conductivity on the surface of the metal substrate is of great significance to improving the heat dissipation capacity of the metal heat dissipation structure with a large specific surface area. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a carbon nanotube array / metal composite heat dissipation material and a preparation method thereof. The metal substrate and the carbon nanotube array are connected by a high thermal conductivity silicon carbide layer, which has high radiation heat dissipation capacity and overall heat dissipation capacity.

[0006] The technical purpose of the present invention is achieved through the following technical solutions.

[0007] A carbon nanotube array-metal composite heat dissipation material consists of a carbon nanotube array and a metal. The carbon nanotube array is perpendicular to the metal surface and evenly distributed on the metal surface. The carbon nanotube array and the metal are connected via a silicon carbide layer.

[0008] Moreover, in the carbon nanotube array, the carbon nanotube diameter is 20-140nm, the length is greater than 190μm (190-800μm), and the array density is greater than 5×10 7 cm -2 (5~9×10 7 cm -2 ).

[0009] The preparation method of the above material is carried out according to the following steps:

[0010] Step 1: Setting a silicon carbide carrier layer on the metal surface

[0011] The polycarbosilane is uniformly dispersed in xylene to form a carrier layer precursor liquid, and then the carrier layer precursor liquid is uniformly coated on the metal surface, and after drying, it is placed in a tube furnace, and in an inert protective gas and hydrogen mixed atmosphere, the temperature is raised from room temperature 20 to 25°C to 900 to 1000°C for insulation, so as to decompose the polycarbosilane into silicon carbide, and obtain a metal with a silicon carbide carrier layer attached to the surface;

[0012] Step 2, Growth of carbon nanotube arrays

[0013] The metal obtained in step 1 is placed in a tubular furnace and heated to 800-900° C., a catalyst carbon source solution is injected into the tubular furnace through a microinjection pump and kept warm to grow a carbon nanotube array, thereby obtaining a metal having a carbon nanotube array on its surface; ferrocene is uniformly dispersed in xylene to prepare a catalyst carbon source solution, wherein the ferrocene concentration is 0.02-0.06 g / mL.

[0014] Furthermore, the metal is immersed in dilute hydrochloric acid (such as 1M) to remove the surface oxide layer. Subsequently, the surface of the metal sheet is cleaned with deionized water, acetone, and ethanol, and then dried.

[0015] Furthermore, in step 1, the metal is a metal sheet, such as a copper sheet, an aluminum sheet, an aluminum alloy sheet or a stainless steel sheet.

[0016] Furthermore, in step 1, the thickness of the metal sheet is 50 to 300 μm, preferably 100 to 300 μm.

[0017] Moreover, in the carrier layer precursor solution of step 1, the concentration of polycarbosilane is 0.01 to 0.15 g / mL, preferably 0.5 to 0.1 g / mL.

[0018] Furthermore, in step 1, the inert protective gas is argon, helium or nitrogen.

[0019] Moreover, in step 1, the inert protective gas flow rate is 500-1000 sccm, and the hydrogen gas flow rate is 30-80 sccm.

[0020] Furthermore, in step 1, during drying, the metal uniformly coated with the carrier layer precursor solution is placed in a forced air drying oven and dried at 60-80° C. for 1-3 hours.

[0021] Furthermore, in step 1, the temperature is increased from room temperature (20-25°C) to 900-1000°C at a heating rate of 10-15°C / min and maintained for 1-5 hours, preferably at 950-1000°C for 1-3 hours.

[0022] Furthermore, in step 2, the temperature is increased from room temperature 20 to 25°C to 800 to 900°C at a heating rate of 10 to 15°C / min and maintained for 10 to 60 minutes, preferably at 860 to 900°C for 20 to 40 minutes.

[0023] Furthermore, in step 2, a medical syringe is used to inject the catalyst carbon source solution into the tube furnace at a uniform rate of 10 to 30 mL / h under the action of a microinjection pump.

[0024] The present invention uses chemical vapor deposition to in-situ grow carbon nanotube arrays on the surface of metal sheets. The obtained carbon nanotubes have a diameter of 20 to 140 nm, a length of more than 190 μm (190 to 800 μm), and an array density of more than 5×107 cm -2 (5~9×10 7 cm -2 ). The orientation direction of the carbon nanotubes is perpendicular to the plane direction of the metal sheet, and they are evenly and densely distributed on the surface of the metal sheet, which plays a role in quickly diffusing the heat from the metal substrate to the external environment through heat conduction and heat radiation. The carbon nanotube array and the metal substrate are firmly connected through the silicon carbide layer, and the thermal conductivity of silicon carbide is better than that of traditional polymer adhesives, which significantly reduces the interfacial thermal resistance. The resulting sheet is easy to process into the desired shape, and its heat dissipation capacity is better than that of traditional metal heat dissipation materials for insufficient heat convection in confined spaces and vacuum systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of the carbon nanotube array / metal composite material of the present invention.

[0026] Figure 2 This is a scanning electron microscope image of a copper sheet with a silicon carbide carrier layer on its surface.

[0027] Figure 3 Energy dispersive X-ray spectrogram of copper sheet with silicon carbide carrier layer on the surface (derived from Figure 2 yellow frame).

[0028] Figure 4 This is a scanning electron microscope image of the cross section of the carbon nanotube array / copper sheet obtained in the present invention.

[0029] Figure 5 This is a scanning electron microscope image of the carbon nanotube array obtained in the present invention. DETAILED DESCRIPTION

[0030] Four embodiments of the present invention are given below to further illustrate the present invention, but not to limit the scope of the present invention. Reference Improving thermal conductivity in the through-thickness direction of carbon fibre / SiC composites by growing vertically aligned carbon nanotubes, Carbon 116 (2017) 84-93, for obtaining polycarbosilane and high temperature treatment.

[0031] Example 1

[0032] 1) Surface treatment of metal sheets: A copper sheet with a thickness of 300 μm was immersed in dilute hydrochloric acid to remove the surface oxide layer. The surface of the copper sheet was then cleaned with deionized water, acetone, and ethanol, and dried.

[0033] 2) Attachment of silicon carbide carrier layer: polycarbosilane is dissolved in xylene to prepare a 0.15 g / mL carrier layer precursor solution, the carrier layer precursor solution is dipped with a brush and evenly coated on the surface of the copper sheet obtained in step 1), placed in a forced air drying oven and dried at 80°C for 1 h, then placed in a tubular furnace, 500 sccm argon and 50 sccm hydrogen are introduced for protection, the temperature is raised to 1000°C, and the temperature is kept for 60 min to decompose the polycarbosilane into silicon carbide, and the copper sheet with a silicon carbide carrier layer attached to the surface is obtained by natural cooling.

[0034] 3) Growth of carbon nanotube array: Ferrocene was dissolved in xylene to prepare a catalyst carbon source solution with a concentration of 0.06 g / mL. The metal sheet obtained in step 2) was placed in a tube furnace and heated to 860°C. After reaching the set temperature, the catalyst carbon source solution was injected into the tube furnace at a rate of 20 mL / h through a micro-injection pump and kept warm for 10 minutes to grow the carbon nanotube array and obtain a copper sheet with a carbon nanotube array on the surface.

[0035] Scanning electron microscopy showed that the length of the carbon nanotubes was 190 μm and the array density was 5×10 7 cm -2 To illustrate the heat dissipation effect of the new material, the carbon nanotube-free side of the obtained sheet was placed on a hot plate at 80°C, and another blank copper sheet was attached at the same time. Using an infrared thermal imager, it was found that the temperature of the carbon nanotube surface of the sheet was 3.4°C higher than that of the blank copper sheet, indicating that the sheet obtained by the present invention has better heat dissipation.

[0036] Example 2

[0037] 1) Surface treatment of metal sheets: A copper sheet with a thickness of 300 μm was immersed in dilute hydrochloric acid to remove the surface oxide layer. The surface of the copper sheet was then cleaned with deionized water, acetone, and ethanol, and dried.

[0038] 2) Attachment of silicon carbide carrier layer: polycarbosilane is dissolved in xylene to prepare a 0.15 g / mL carrier layer precursor solution, the carrier layer precursor solution is dipped with a brush and evenly coated on the surface of the copper sheet obtained in step 1), placed in a forced air drying oven and dried at 80°C for 1 h, then placed in a tubular furnace, 500 sccm argon and 50 sccm hydrogen are introduced for protection, the temperature is raised to 1000°C, and the temperature is kept for 60 min to decompose the polycarbosilane into silicon carbide, and the copper sheet with a silicon carbide carrier layer attached to the surface is obtained by natural cooling.

[0039] 3) Growth of carbon nanotube array: Ferrocene was dissolved in xylene to prepare a catalyst carbon source solution with a concentration of 0.06 g / mL. The metal sheet obtained in step 2) was placed in a tubular furnace and heated to 860°C. After reaching the set temperature, the catalyst carbon source solution was injected into the tubular furnace at a rate of 20 mL / h through a microinjection pump and kept warm for 30 minutes to grow the carbon nanotube array and obtain a copper sheet with a carbon nanotube array on the surface.

[0040] Scanning electron microscopy measured the carbon nanotube length to be 510 μm and the array density to be 8×10 7 cm -2 To illustrate the heat dissipation effect of the new material, the carbon nanotube-free side of the obtained sheet was placed on a hot plate at 80°C, and another blank copper sheet was attached at the same time. Using an infrared thermal imager, it was found that the temperature of the carbon nanotube surface of the sheet was 4.6°C higher than that of the blank copper sheet, indicating that the sheet obtained by the present invention has better heat dissipation.

[0041] Example 3

[0042] 1) Surface treatment of metal sheets: A copper sheet with a thickness of 300 μm was immersed in dilute hydrochloric acid to remove the surface oxide layer. The surface of the copper sheet was then cleaned with deionized water, acetone, and ethanol, and dried.

[0043] 2) Attachment of silicon carbide carrier layer: polycarbosilane is dissolved in xylene to prepare a 0.15 g / mL carrier layer precursor solution, the carrier layer precursor solution is dipped with a brush and evenly coated on the surface of the copper sheet obtained in step 1), placed in a forced air drying oven and dried at 80°C for 1 h, then placed in a tubular furnace, 500 sccm argon and 50 sccm hydrogen are introduced for protection, the temperature is raised to 1000°C, and the temperature is kept for 60 min to decompose the polycarbosilane into silicon carbide, and the copper sheet with a silicon carbide carrier layer attached to the surface is obtained by natural cooling.

[0044] 3) Growth of carbon nanotube array: Ferrocene was dissolved in xylene to prepare a catalyst carbon source solution with a concentration of 0.06 g / mL. The metal sheet obtained in step 2) was placed in a tubular furnace and heated to 860°C. After reaching the set temperature, the catalyst carbon source solution was injected into the tubular furnace at a rate of 20 mL / h through a microinjection pump and kept warm for 60 minutes to grow the carbon nanotube array and obtain a copper sheet with a carbon nanotube array on the surface.

[0045] Scanning electron microscopy measured the carbon nanotube length to be 790 μm and the array density to be 9×10 7 cm -2 To illustrate the heat dissipation effect of the new material, the carbon nanotube-free side of the obtained sheet was placed on a hot plate at 80°C, and another blank copper sheet was attached at the same time. Using an infrared thermal imager, it was found that the temperature of the carbon nanotube surface of the sheet was 4.9°C higher than that of the blank copper sheet, indicating that the sheet obtained by the present invention has better heat dissipation.

[0046] Example 4

[0047] 1) Surface treatment of metal sheets: immerse aluminum foil with a thickness of 50 μm in dilute hydrochloric acid to remove the surface oxide layer, and take it out immediately when a small amount of bubbles emerge. Then use deionized water, acetone, and ethanol to clean the surface of the aluminum sheet and dry it.

[0048] 2) Attachment of silicon carbide carrier layer: polycarbosilane is dissolved in xylene to prepare a 0.15 g / mL carrier layer precursor solution, the carrier layer precursor solution is dipped with a brush and evenly coated on the surface of the aluminum sheet obtained in step 1), placed in a forced air drying oven and dried at 80°C for 1 h, then placed in a tubular furnace, 500 sccm argon and 50 sccm hydrogen are introduced for protection, the temperature is raised to 1000°C, and the temperature is kept for 60 min to decompose the polycarbosilane into silicon carbide, and the aluminum sheet with a silicon carbide carrier layer attached to the surface is obtained by natural cooling.

[0049] 3) Growth of carbon nanotube array: Ferrocene was dissolved in xylene to prepare a catalyst carbon source solution with a concentration of 0.02 g / mL. The aluminum sheet obtained in step 2) was placed in a tube furnace and heated to 860°C. After reaching the set temperature, the catalyst carbon source solution was injected into the tube furnace at a rate of 20 mL / h through a microinjection pump and kept warm for 10 minutes to grow the carbon nanotube array and obtain an aluminum sheet with a carbon nanotube array on the surface.

[0050] Scanning electron microscopy showed that the length of the carbon nanotubes was 210 μm and the array density was 5×10 7 cm -2 To illustrate the heat dissipation effect of the new material, the carbon nanotube-free side of the obtained sheet was placed on a hot plate at 80°C, and another blank aluminum sheet was attached at the same time. Using an infrared thermal imager, it was found that the temperature of the carbon nanotube surface of the sheet was 2.6°C higher than that of the blank aluminum sheet, indicating that the sheet obtained by the present invention has better heat dissipation.

[0051] By adjusting the process parameters according to the present invention, the preparation of new materials can be achieved, and the performance is basically consistent with that of the present invention. After the surface is modified by the carbon nanotube array, the heat dissipation performance of the metal material is significantly better than that of the original metal material.

[0052] The present invention is described above by way of example. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacement that can be made by those skilled in the art without inventive effort falls within the protection scope of the present invention.

Claims

1. A metal-based carbon nanotube array composite heat dissipation material, characterized in that: It consists of a carbon nanotube array and metal. The carbon nanotube array is perpendicular to the metal surface and evenly distributed on the metal surface. The carbon nanotube array and the metal are connected by a silicon carbide layer.

2. The metal-based carbon nanotube array composite heat dissipation material according to claim 1, characterized in that: In the carbon nanotube array, the diameter of the carbon nanotube is 20-140nm, the length is 190-800μm, and the array density is 5-9×10 7 cm -2 The metal is a metal sheet, such as a copper sheet, an aluminum sheet, an aluminum alloy sheet or a stainless steel sheet; the thickness of the metal sheet is 50 to 300 μm, preferably 100 to 300 μm.

3. A method for preparing a metal-based carbon nanotube array composite heat dissipation material, characterized in that: Follow the steps below: Step 1: Setting a silicon carbide carrier layer on the metal surface The polycarbosilane is uniformly dispersed in xylene to form a carrier layer precursor liquid, and then the carrier layer precursor liquid is uniformly coated on the metal surface, and after drying, it is placed in a tube furnace, and in an inert protective gas and hydrogen mixed atmosphere, the temperature is raised from room temperature 20 to 25°C to 900 to 1000°C for insulation, so as to decompose the polycarbosilane into silicon carbide, and obtain a metal with a silicon carbide carrier layer attached to the surface; Step 2, Growth of carbon nanotube arrays The metal obtained in step 1 is placed in a tubular furnace and heated to 800-900° C., a catalyst carbon source solution is injected into the tubular furnace through a microinjection pump and kept warm to grow a carbon nanotube array, thereby obtaining a metal having a carbon nanotube array on its surface; ferrocene is uniformly dispersed in xylene to prepare a catalyst carbon source solution, wherein the ferrocene concentration is 0.02-0.06 g / mL.

4. The method for preparing a metal-based carbon nanotube array composite heat dissipation material according to claim 3, characterized in that: In the carrier layer precursor solution of step 1, the concentration of polycarbosilane is 0.01-0.15 g / mL, preferably 0.5-0.1 g / mL. The inert protective gas is argon, helium or nitrogen; the inert protective gas flow rate is 500-1000 sccm, and the hydrogen flow rate is 30-80 sccm. In step 1, the temperature is increased from room temperature 20-25°C to 900-1000°C at a heating rate of 10-15°C / min and kept warm for 1-5 hours. In step 2, the temperature is increased from room temperature 20-25°C to 800-900°C at a heating rate of 10-15°C / min and kept warm for 10-60 minutes. Use a medical syringe to inject the catalyst carbon source solution into the tubular furnace at a uniform rate of 10-30 mL / h under the action of a microinjection pump.

5. A metal-based carbon nanotube array composite material prepared according to the preparation method according to any one of claims 1 to 4.

6. An application of the metal-based carbon nanotube array composite material according to claim 5 in the field of thermal management.

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