Graphene copper-based composite material with high thermal conductivity and preparation method and application thereof

Abstract

The invention provides a high-heat-conductivity graphene copper-based composite material and a preparation method and application thereof. The method comprises the steps that (1) graphene layers are deposited on the two sides of a copper foil through a chemical vapor deposition method, a graphene copper foil material is obtained, the thickness of the copper foil ranges from 8 micrometers to 35 micrometers, and the thickness of the graphene layer on the single side ranges from 0.34 nm to 4 nm; and (2) multiple layers of graphene copper foil materials are stacked and subjected to hot pressing, and the graphene copper-based composite material is obtained. The graphene copper-based composite material prepared through the method has excellent heat conductivity, and the method is easy to operate, high in production efficiency, low in cost and suitable for large-area popularization.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite materials, and in particular relates to a graphene copper-based composite material and a preparation method and application thereof. Background Art

[0002] In recent years, the power density demand of electronic devices has been increasing, and they are constantly developing towards miniaturization and micro-miniaturization. The power density per unit volume has increased, and heat has been concentrated. The heating problem of conductor materials in electronic products has become a key factor restricting their development. Traditional materials usually cannot meet strict thermal requirements, resulting in overheating of components and shortened life. Conductive materials will generate resistance loss (I²R) when current passes through, resulting in local heat concentration. Therefore, there are two main ways to improve the heat concentration of conductor materials, namely, improving the electrical conductivity of the material to reduce resistance loss, and improving the thermal conductivity of the material to improve heat dissipation efficiency.

[0003] Copper is one of the most widely used conductive materials, which is mainly due to its excellent properties. Copper has electrical and thermal conductivity second only to silver. At room temperature, the electrical conductivity of pure copper is about 5.8×10 7 S / m, and the thermal conductivity is about 385 W / (m·K). Therefore, copper and its composite materials are widely used in high-performance electronic devices and thermal management systems. Graphene is a two-dimensional crystalline material with a hexagonal honeycomb structure formed by sp² hybridization of carbon atoms, which has excellent electrical, thermal and mechanical properties. Graphene has an extremely high electron mobility, which can reach 200,000 cm² / Vs at room temperature. At the same time, its theoretical thermal conductivity is as high as 5300 W / mK. It is of great research value to apply graphene to the preparation of copper-based materials and improve the thermal conductivity of materials. Although graphene and copper are composited to prepare graphene-copper composite materials, the preparation method is too complicated, the production cost is high, or the thermal conductivity of the obtained graphene-copper composite materials is not significantly improved, or even because of the poor combination of graphene and copper, the thermal conductivity of the obtained composite materials is lower than that of pure copper. Therefore, how to achieve efficient and low-cost graphene and copper effective compounding, compared with pure copper, the thermal conductivity of the composite material is significantly improved, which is of great significance. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the prior art to at least a certain extent. To this end, one object of the present invention is to provide a high thermal conductivity graphene copper-based composite material and a preparation method and application thereof.

[0005] In a first aspect of the present invention, the present invention provides a method for preparing a high thermal conductivity graphene copper-based composite material, the method comprising: (1) A graphene layer is deposited on both sides of a copper foil by chemical vapor deposition to obtain a graphene copper foil material, wherein the thickness of the copper foil is 8 μm to 35 μm, and the thickness of the graphene layer on one side is 0.34 nm to 4 nm; (2) stacking and hot pressing multiple layers of the graphene copper foil material to obtain a graphene copper-based composite material.

[0006] According to the preparation method of the above-mentioned high thermal conductivity graphene copper-based composite material provided by the present invention, copper foil with double-sided graphene layer grown by chemical vapor deposition (CVD) is used as raw material, and the preparation of graphene film can be completed by a suspended vertical furnace. The carbon source is decomposed by heating at high temperature and reacts with the copper substrate, thereby continuously growing on the surface to form a graphene layer of a certain thickness, wherein the carbon atoms of the graphene lattice are in direct contact with the copper atoms of the copper substrate through van der Waals force, which greatly improves the contact between graphene and copper, minimizes the interface thermal resistance, is beneficial to the interface heat transfer, and further improves the thermal conductivity of the graphene copper-based composite material.

[0007] On the basis of the above-mentioned chemical vapor deposition graphene, the inventors found that the thickness of the copper foil and the thickness of the deposited graphene layer have a decisive influence on the thermal conductivity of the graphene copper-based composite material. Specifically, by controlling the thickness of the copper foil to 8μm~35μm and the thickness of the single-sided graphene layer to 0.34nm~4nm, the thermal conductivity of the graphene copper-based composite material can be effectively improved. If the thickness of the single-sided graphene layer is too thick, not only the high thermal conductivity of the graphene is not fully utilized, but the thermal conductivity of the graphene copper-based composite material will be significantly reduced, even lower than the thermal conductivity of pure copper. Therefore, the present invention can greatly improve the thermal conductivity of the graphene copper-based material by controlling the thickness of the graphene layer and the thickness of the copper foil. It may be because controlling the thickness of the graphene layer can improve the good interface bonding between the graphene and the copper matrix, which reduces the interface thermal resistance; at the same time, the quasi-continuous directional arrangement of graphene constructs a fast heat transfer path, thereby increasing the in-plane thermal conductivity of the copper-based composite material by 12.5%.

[0008] Then, the multiple layers of the graphene copper foil materials formed above are stacked and hot pressed to prepare a graphene copper-based composite material having a layered structure (such as Figure 1 ), by adjusting the hot pressing temperature, pressure and time, the graphene copper foil forms a good metallurgical bond and reduces the interface thermal resistance. Graphene forms a quasi-continuous directional arrangement in the copper matrix material (such as Figure 2 ), constructing a fast heat transfer path, which can improve the thermal conductivity of graphene copper-based composites.

[0009] Therefore, the graphene copper-based composite material prepared by the method has excellent thermal conductivity, and the method is easy to operate, has high production efficiency, low cost, and is suitable for large-scale promotion.

[0010] According to the method for preparing a high thermal conductivity graphene copper-based composite material provided by the present invention, the thickness of the copper foil is preferably 15 μm to 30 μm. For example, the thickness of the copper foil is 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, etc., or a range between any two of the above values. By controlling the thickness of the copper foil within the above range, the thermal conductivity of the graphene copper-based composite material can be improved.

[0011] According to the preparation method of the high thermal conductivity graphene copper-based composite material provided by the present invention, the thickness of the graphene layer on one side is preferably 0.34nm~2nm. For example, the thickness of the graphene layer on one side is approximately 0.34nm, 0.5nm, 1nm, 1.5nm, 2nm, 2.5nm, 3nm, 3.5nm, 4nm, etc., or the range between any two of the above values. By controlling the thickness of the graphene layer on one side within the above range, the thermal conductivity of the graphene copper-based composite material can be improved.

[0012] According to the preparation method of the high thermal conductivity graphene copper-based composite material provided by the present invention, the gases used in the chemical vapor deposition method are methane and hydrogen, the volume ratio of the methane to the hydrogen is 1:(2-4), and the graphene growth time is 5min-40min. The growth gases used are methane, hydrogen and argon, and the growth thickness of the graphene is regulated by adjusting the ratio of methane and hydrogen, the growth time, etc.

[0013] According to the method for preparing a high thermal conductivity graphene copper-based composite material provided by the present invention, in step (2), the number of layers of the graphene copper foil material used in the lamination is not less than 5 layers, preferably 10 to 50 layers.

[0014] According to the method for preparing the high thermal conductivity graphene copper-based composite material provided by the present invention, the temperature of the hot pressing is 700°C to 1000°C. For example, the temperature of the hot pressing is 700°C, 800°C, 900°C, 1000°C, etc., or a range between any two of the above values. By controlling the temperature of the hot pressing within the above range, a good metallurgical bond can be formed between the graphene and the copper foil, the interface thermal resistance can be reduced, and the thermal conductivity of the graphene copper-based composite material can be improved.

[0015] According to the preparation method of the high thermal conductivity graphene copper-based composite material provided by the present invention, the hot pressing time is 0.5h~6h. For example, the hot pressing time is 0.5h, 1h, 2h, 3h, 4h, 5h, 6h, etc., or the range between any two of the above values. Controlling the hot pressing time within the above range can form a good metallurgical bond between the graphene and the copper foil, reduce the interface thermal resistance, and improve the thermal conductivity of the graphene copper-based composite material.

[0016] According to the preparation method of the high thermal conductivity graphene copper-based composite material provided by the present invention, the pressure of the hot pressing is 10MPa~50MPa. For example, the pressure of the hot pressing is 10MPa, 20MPa, 30MPa, 40MPa, 50MPa, etc., or the range between any two values ​​of the above. Controlling the pressure of the hot pressing within the above range can form a good metallurgical bond between the graphene and the copper foil, reduce the interface thermal resistance, and improve the thermal conductivity of the graphene copper-based composite material.

[0017] Preferably, the multi-layer graphene copper foil material is stacked and hot pressed, the hot pressing temperature is 700° C. to 1000° C., the hot pressing time is 1 h to 6 h, and the hot pressing pressure is 10 MPa to 50 MPa.

[0018] In a second aspect of the present invention, the present invention provides a high thermal conductivity graphene copper-based composite material, which is prepared by the above method. Thus, the graphene copper-based composite material has a high thermal conductivity, specifically, the thermal conductivity of the graphene copper-based composite material is 425W / (m·K)-460W / (m·K).

[0019] In the third aspect of the present invention, the present invention proposes the application of the above-mentioned high thermal conductivity graphene copper-based composite material in the field of electric drive devices or electric control equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 It is a schematic diagram of the hot pressing process of the high thermal conductivity graphene copper-based composite material provided by the present invention; Figure 2 This is an electron microscope photograph of the cross section of the high thermal conductivity graphene copper-based composite material provided by the present invention. DETAILED DESCRIPTION

[0022] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The present invention is described below with reference to specific embodiments. It should be noted that these embodiments are merely illustrative and do not limit the present invention in any way.

[0023] Example 1 The preparation method of the high thermal conductivity graphene copper-based composite material of this embodiment is as follows: (1) Using a suspended vertical furnace, graphene was deposited on both sides of a 25 μm thick copper foil by chemical vapor deposition (CVD) to prepare graphene copper foil. The growth gases used were methane, hydrogen and argon. The thickness of the single-sided graphene layer was adjusted to 1.8 nm~2 nm by adjusting the ratio of methane and hydrogen, the growth time and the growth pressure.

[0024] (2) The copper foil with graphene layers deposited on both sides was cut into the same size, and 25 layers of the copper foil with graphene layers deposited on both sides were stacked. The copper foil size was 5 cm × 5 cm. The copper foil was placed in a hot press furnace and hot pressed at 950°C and 10 MPa for 2 h to obtain a graphene copper-based composite material.

[0025] The thermal conductivity of the graphene copper-based composite material provided in this embodiment is measured, and the specific method is as follows: The graphene copper-based composite material obtained by hot pressing is cut into discs with a diameter of 25.4 mm, and the upper and lower surfaces of the discs are polished to a thickness of 0.5 (± 0.01) mm. The surface should be flat and the parallel error should be within 0.5% of the thickness for thermal conductivity testing. First, in accordance with the national standard "Plastic Differential Scanning Calorimetry (DSC) Part 4: Determination of Specific Heat Capacity" (GB / T19466.4-2016), the specific heat capacity (Cp, unit: J / (kg·K)) of the graphene copper-based composite material is tested by DSC, Cp=0.4 J / (kg·K). The density of the graphene copper-based composite material is measured by the volume method, ρ=8.89 kg / m 3 The thermal diffusivity (α, unit: mm) of the graphene copper composite disc was measured using a NETZSCH laser thermal conductivity meter (LFA 467) in accordance with the national standard "Flash Method for Measurement of Thermal Diffusivity or Thermal Conductivity" (GBT22588-2008) and a matching NETZSCH In-Plane mold. 2 / s), α=126.56 mm 2 / s. Finally, the thermal conductivity (λ, unit W / (m·K)) of the graphene copper matrix composite sample was calculated by the formula: The calculated thermal conductivity is 450.05 W / (m·K).

[0026] Example 2 The preparation method of the high thermal conductivity graphene copper-based composite material of this embodiment is as follows: (1) Using a suspended vertical furnace, graphene was deposited on both sides of a 25 μm thick copper foil by chemical vapor deposition (CVD) to prepare graphene copper foil. The growth gases used were methane, hydrogen and argon. The thickness of the single-sided graphene layer was adjusted to 3-4 nm by adjusting the ratio of methane and hydrogen, the growth time and the growth pressure.

[0027] (2) The copper foil with graphene layers deposited on both sides was cut into the same size, and 25 layers of the copper foil with graphene layers deposited on both sides were stacked. The copper foil size was 50 cm × 50 cm. The copper foil was placed in a hot press furnace and hot pressed at 1000°C and 10 MPa for 3 h to obtain a graphene copper-based composite material.

[0028] The thermal conductivity of the graphene copper-based composite material provided in this embodiment is measured. The measurement process is the same as in Example 1. The specific heat capacity of the graphene copper-based composite material is measured to be Cp=0.4 J / (kg·K). The density of the graphene copper-based composite material is measured by the volume method to be ρ=8.89 kg / m 3 , the thermal diffusion coefficient is λ=122.15 mm 2 / s, the calculated thermal conductivity is 434.37W / (m·K).

[0029] Example 3 The preparation method of the high thermal conductivity graphene copper-based composite material of this embodiment is as follows: (1) Graphene was deposited on both sides of a 35 μm thick copper foil by chemical vapor deposition (CVD) in a suspended vertical furnace to prepare graphene copper foil. The growth gases used were methane, hydrogen and argon. The thickness of the single-sided graphene layer was adjusted to 0.34 nm~0.5 nm by adjusting the ratio of methane and hydrogen, the growth time and the growth pressure.

[0030] (2) Cut the copper foil with graphene layers deposited on both sides into the same size, stack 25 layers of the copper foil with graphene layers deposited on both sides, and place the graphene copper foil stack with a copper foil size of 50 cm × 50 cm in a hot press furnace, and hot press at 900°C and 10 MPa for 1.5 h to obtain a graphene copper-based composite material.

[0031] The thermal conductivity of the graphene copper-based composite material provided in this embodiment is measured. The measurement process is the same as in Example 1. The specific heat capacity Cp of the graphene copper-based composite material is measured by DSC method, which is 0.4 J / (kg·K). The density of the graphene copper-based composite material is measured by volume method, which is ρ=8.89 kg / m 3 , the thermal diffusion coefficient is λ=120.32 mm 2 / s, and the calculated thermal conductivity is 427.86 W / (m·K).

[0032] Comparative Example 1 In this comparative example, a hot pressed pure copper comparison sample was prepared, and the preparation method thereof is as follows: (1) A copper foil with a thickness of 25 μm was cut into a size of 5 cm × 5 cm. 25 layers of copper foil were stacked and placed in a hot pressing furnace. They were hot pressed at 950 °C and 10 MPa for 2 h to obtain a hot pressed pure copper comparison sample.

[0033] The thermal conductivity of the graphene copper-based composite material provided in this comparative example was measured. The measurement process was the same as in Example 1. The specific heat capacity of hot-pressed pure copper was measured to be Cp=0.39 J / (kg·K). The density of the graphene copper-based composite material was measured by the volume method to be ρ=8.89 kg / m 3 , the thermal diffusion coefficient is λ=113.04 mm 2 / s, and the calculated thermal conductivity is 387.95 W / (m·K).

[0034] Comparative Example 2 The difference between the preparation method of the graphene copper-based composite material of this comparative example and that of Example 1 is as follows: (1) Using a suspended vertical furnace, graphene was deposited on both sides of a 25 μm thick copper foil by chemical vapor deposition (CVD) to prepare graphene copper foil. The growth gases used were methane, hydrogen and argon. The thickness of the single-sided graphene layer was adjusted to 5 nm~6 nm by adjusting the ratio of methane and hydrogen, the growth time and the growth pressure.

[0035] The thermal conductivity of the graphene copper-based composite material provided in this comparative example was measured. The measurement process was the same as in Example 1. The specific heat capacity Cp of the graphene copper-based composite material was measured by DSC method, which was 0.40 J / (kg·K). The density of the graphene copper-based composite material was measured by volume method, which was ρ=8.89 kg / m 3 , the thermal diffusion coefficient is λ=116.12mm 2 / s, the calculated thermal conductivity is 412.92W / (m·K).

[0036] Comparative Example 3 The difference between the preparation method of the graphene copper-based composite material of this comparative example and that of Example 1 is as follows: (1) Graphene was deposited on both sides of a 25 μm thick copper foil by chemical vapor deposition (CVD) in a suspended vertical furnace to prepare graphene copper foil. The growth gases used were methane, hydrogen and argon. The thickness of the single-sided graphene layer was adjusted to 9-10 nm by adjusting the ratio of methane and hydrogen, the growth time and the growth pressure.

[0037] The thermal conductivity of the graphene copper-based composite material provided in this comparative example was measured. The measurement process was the same as in Example 1. The specific heat capacity Cp of the graphene copper-based composite material was measured by DSC method, which was 0.40 J / (kg·K). The density of the graphene copper-based composite material was measured by volume method, which was ρ=8.89 kg / m 3 , the thermal diffusion coefficient is λ=108.5mm 2 / s, the calculated thermal conductivity is 385.83W / (m·K).

[0038] Comparative Example 4 The preparation method of the graphene copper-based composite material of this comparative example is as follows: (1) Using a suspended vertical furnace, graphene was deposited on both sides of a copper foil with a thickness of 45 μm by chemical vapor deposition (CVD) to prepare graphene copper foil. The growth gases used were methane, hydrogen and argon. The thickness of the single-sided graphene layer was adjusted to 3.5-3.8 nm by adjusting the ratio of methane and hydrogen, the growth time and the growth pressure.

[0039] (2) The copper foil with graphene layers deposited on both sides was cut into the same size, and 25 layers of the copper foil with graphene layers deposited on both sides were stacked. The copper foil size was 50 cm × 50 cm. The copper foil was placed in a hot press furnace and hot pressed at 1000°C and 10 MPa for 3 h to obtain a graphene copper-based composite material.

[0040] The thermal conductivity of the graphene copper-based composite material provided in this comparative example was measured. The measurement process was the same as in Example 1. The specific heat capacity of the graphene copper-based composite material was measured to be Cp=0.39 J / (kg·K). The density of the graphene copper-based composite material was measured by the volume method to be ρ=8.89 kg / m 3 , the thermal diffusion coefficient is λ=115.35 mm 2 / s, the calculated thermal conductivity is 399.93W / (m·K).

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a high thermal conductivity graphene copper-based composite material, characterized in that: include: (1) A graphene layer is deposited on both sides of a copper foil by chemical vapor deposition to obtain a graphene copper foil material, wherein the thickness of the copper foil is 8 μm to 35 μm, and the thickness of the graphene layer on one side is 0.34 nm to 4 nm; (2) stacking and hot pressing multiple layers of the graphene copper foil material to obtain a graphene copper-based composite material.

2. The method according to claim 1, characterized in that: The copper foil has a thickness of 15 μm to 30 μm.

3. The method according to claim 1, characterized in that: The thickness of the graphene layer on one side is 0.34nm~2nm.

4. The method according to any one of claims 1 to 3, characterized in that: The gases used in the chemical vapor deposition method are methane and hydrogen, the volume ratio of the methane to the hydrogen is 1:(2-4), and the graphene growth time is 5 min-40 min.

5. The method according to any one of claims 1 to 3, characterized in that: In step (2), the number of layers of the graphene copper foil material used in the stacking process is not less than 5 layers, preferably 10 to 50 layers.

6. The method according to claim 1, characterized in that: The temperature of the hot pressing is 700°C to 1000°C; And / or, the hot pressing time is 0.5h~6h.

7. The method according to claim 1 or 6, characterized in that: The hot pressing pressure is 10MPa~50MPa.

8. A high thermal conductivity graphene copper-based composite material, characterized in that: The method is prepared by any one of claims 1 to 7.

9. The composite material according to claim 8, characterized in that: The thermal conductivity of the high thermal conductivity graphene copper-based composite material is 425W / (m·K)-460W / (m·K).

10. Application of the high thermal conductivity graphene copper-based composite material according to claim 8 or 9 in the field of electric drive devices or electric control equipment.

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