WO2023216407A1 - Preparation method for graphene/copper composite material combining physical vapor deposition and chemical vapor deposition - Google Patents

Abstract

A preparation method for a graphene/copper composite material combining physical vapor deposition (PVD) and chemical vapor deposition (CVD). According to the method, a layer of graphene material is deposited on the surface of a copper foil by means of CVD, a layer of copper material is deposited on the surface of the graphene material by means of PVD, and CVD is re-performed on the surface of the deposited copper material to deposit a graphene material, such that a graphene/copper composite material having a multi-layer structure is prepared by means of repeated deposition. The material is compounded by using two materials of pure copper and graphene; the tensile strength of the composite material is greater than or equal to 200 MPa, and is at the same level as that of pure copper; the conductivity of the composite material is greater than or equal to that of 110% IACS, and compared with the conductivity of pure copper, is increased by 10% or above; and compared with the skin depth of pure copper, the skin depth is increased by 30%. The material can replace a traditional copper material or silver material, is applied to a supercapacitor or a motor driving apparatus, and has the effects of improving the efficiency, reducing the temperature rise, and the like.

Description

Preparation method of graphene/copper composite material combining physical vapor deposition and chemical vapor deposition

cross reference

This application claims the priority of Chinese patent application No. 202210531620.2, titled "Preparation method of graphene/copper composite material combining physical vapor deposition and chemical vapor deposition" submitted on May 13, 2022, and its entire disclosure content This article is incorporated by reference in its entirety.

Technical field

The invention belongs to the field of material technology and relates to a method for preparing a graphene/copper composite material that combines physical vapor deposition and chemical vapor deposition. The composite material has excellent conductive properties.

Background technique

Graphene/copper composite materials are used in the field of power electronic transmission due to their ultra-high electrical conductivity, good mechanical properties and thermal conductivity, especially in replacing traditional copper materials in high-efficiency traction motors, energy-saving transformers, 5G communications and new energy. Applications in automotive and other fields can reduce copper loss, reduce temperature rise and improve efficiency.

Metal copper has the advantages of high electrical conductivity and high thermal conductivity, and is currently the most important conductive material in power systems. However, current purification and single crystallization technologies have approached the physical limits of copper materials, making it difficult to further reduce electrical losses caused by heat generation.

Graphene, as a new two-dimensional planar material, has excellent mechanical properties and ultra-high carrier mobility. Embedding graphene as a reinforcing phase into metallic copper to form a graphene/copper composite material can significantly improve copper's electrical conductivity, mechanics and other comprehensive properties.

In recent years, there have been many studies on graphene/copper composite materials at home and abroad, mainly using in-situ growth to deposit graphene films on the surface of copper powder, and then using powder metallurgy processes for compression molding. The powder metallurgy method mainly improves the strength of composite materials, but the distribution of graphene in the copper matrix is in a disordered state, which cannot bring out the high electron migration ability of graphene, and has limited improvement in conductive performance.

Contents of the invention

The invention provides a method for preparing graphene/copper composite materials. The tensile strength of the graphene/copper composite materials prepared by this method is ≥200MPa, which is at the same level as pure copper; and its electrical conductivity is ≥110% IACS, which is higher than that of pure copper. The conductivity of pure copper is increased by more than 10%; the skin depth is increased by 30% compared to pure copper.

A preparation method of graphene/copper composite material, including:

1) Provide rolled copper foil; use a chemical vapor deposition (CVD) process to prepare a graphene film on the surface of the rolled copper foil to make a copper/graphene material;

2) Using a high-purity sputtering copper target as the material, a physical vapor deposition (PVD) process is used to deposit a copper film on the surface of the copper/graphene material to make a Cu/C/Cu material;

3) Use a chemical vapor deposition process to prepare a graphene film on the surface of the Cu/C/Cu material to make a Cu/C/Cu/C composite material;

4) Using a high-purity sputtering copper target as the material, a physical vapor deposition (PVD) process is used to deposit a copper film on the surface of the Cu/C/Cu/C composite material to obtain a Cu/C/Cu/C/Cu composite material. ;

5) Continue to repeat steps 3) and 4) to make a graphene/copper composite material with a multi-layer structure.

Further, the thickness of the rolled copper foil in step 1) is between 8-25 μm.

Furthermore, before depositing the graphene film, the rolled copper foil needs to be subjected to hydrogen reduction treatment to remove the gas and oxide layer adsorbed on the surface.

Further, the purity of the copper material used is ≥99.9%, such as 99.9%-99.9999%, specifically such as 99.9%, 99.99%, 99.999%, 99.9999%. It is preferred that the purity of the copper material is ≥99.99%. Research has found that as the purity of copper blocks increases, the corresponding raw material costs also increase exponentially. In order to meet actual production needs, copper blocks with a purity of 99.99% are selected. Among them, the performance of the graphene/copper-based composite material prepared from the copper block with a purity of 99.99% is at the same level as that of the copper block with a purity of 99.999%.

Further, the carbon source used in chemical vapor deposition is methane, ethylene, acetylene, etc.

Further, the temperature of the chemical vapor deposition is 950-1000°C.

Further, the number of layers of the graphene film prepared by each chemical vapor deposition is 1-5 layers, such as 1 layer, 2 layers, 3 layers, 4 layers, and 5 layers. Restricted by the preparation technology, the fewer layers of graphene material, the higher the preparation technology and equipment requirements, and the corresponding cost will be higher. Determined by the properties of the material, the number of graphite layers is less than 5, and it still has a different electronic structure from three-dimensional graphite. Single-layer graphene has excellent performance but will produce wrinkles. The wrinkles will destroy the hexagonal symmetrical lattice structure of graphene and generate long-range scattering barriers, resulting in increased resistance. Therefore, the preparation process is extremely important for controlling the number of graphene layers. The grades of graphene layers in this preparation method are divided into single-layer graphene (1 layer), double-layer graphene (2 layers) and multi-layer graphene (3 layers, 4 layers and 5 layers).

Further, the thickness of the copper film prepared by each physical vapor deposition is 1-15 μm, optionally 3-10 μm, such as 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 12 μm, 15 μm .

Further, the background vacuum of each physical vapor deposition reaches 5.5×10 ^-3 Pa or above, and/or the target power density is 1-10W/cm ² , such as 1W/cm ² , 2W/cm ² , 3W/cm ² , 4W/cm ² , 5W/cm ² , 6W/cm ² , 7W/cm ² , 8W/cm ² , 9W/cm ² , 10W/cm ² .

Further, the target current of the physical vapor deposition is 5-20A.

Further, the temperature of the physical vapor deposition is below 500°C.

According to the embodiment of the present invention, the total number of layers of the graphene/copper composite material with a multi-layer structure is 10-1000 layers, specifically, 10 layers, 50 layers, 100 layers, 200 layers, 300 layers, 400 layers, 500 layers layer, 600 layer, 800 layer, 900 layer, 1000 layer. The thickness of the application target product determines the total number of layers of the graphene/copper composite. Due to the different number of layers, the proportion of graphene is also different. According to the test results of electrical properties, when the number of graphene layers increases from 10, 50, and 100 layers, the conductivity will increase slightly, from 108 %IACS increases to 112%IACS. When the total number of layers is greater than 200 layers, the conductivity becomes consistent with the change of the number of layers. The total number of layers refers to the number of layers of all copper films and the number of layers of graphene films.

Further, in the preparation method, the operation of preparing the copper film and the operation of preparing the graphene film are performed in the same chamber. This can avoid the introduction of impurity elements and damage by mechanical stress during the transfer process of the graphene film, ensuring the integrity and uniformity of the graphene film in the copper matrix.

Further, the above method also includes step 6) further processing the prepared graphene/copper composite material with a multi-layer structure. Specifically, mechanical processing equipment can be used to process finished products that meet the required size and surface quality requirements.

The present invention also includes the graphene/copper composite material with a multi-layer structure prepared by the above method. This material can replace traditional copper materials or silver materials and be used in supercapacitors or motor drive devices to improve efficiency and reduce temperature rise.

The invention also provides an equipment for preparing graphene/copper composite materials, which is used to prepare the above-mentioned graphene/copper composite materials, specifically including a CVD deposition system and a PVD deposition system;

In the CVD deposition system, a chemical vapor deposition (CVD) process is used to prepare a graphene film on the surface of the rolled copper foil to make a copper/graphene material;

In the PVD deposition system, a high-purity sputtering copper target is used as the material, and a physical vapor deposition (PVD) process is used to deposit a copper film on the surface of the copper/graphene material to make a Cu/C/Cu material;

Then in the CVD deposition system, a chemical vapor deposition process is used to prepare a graphene film on the surface of the Cu/C/Cu material to make a Cu/C/Cu/C composite material;

In the PVD deposition system, a high-purity sputtering copper target is used as the material, and a physical vapor deposition (PVD) process is used to deposit a copper film on the surface of the Cu/C/Cu/C composite material to obtain Cu/C/Cu/C/ Cu composite materials;

Repeat the above chemical vapor deposition (CVD) process and physical vapor deposition (PVD) process until a graphene/copper composite material with a multi-layer structure is produced.

Compared with the existing technology, the beneficial effects of the present invention are:

(1) In the present invention, the preparation process is simple and reproducible, which is conducive to industrial large-scale production. Through experiments with different number of layers, a graphene/copper composite material with good interface bonding effect was obtained, which improved the conductivity of the material. During the application process of flat-panel transformers, the temperature rise was reduced and the efficiency was improved.

(2) In the present invention, the two materials are compositely deposited in the same chamber, which avoids the introduction of impurity elements and the damage of mechanical stress during the transfer process of the graphene film, and ensures the integrity of the graphene film in the copper matrix. and uniformity.

Description of the drawings

Figure 1 is a schematic structural diagram of equipment used to prepare graphene/copper composite materials according to an embodiment of the present invention.

In Figure 1, 1: CVD deposition system; 2: PVD deposition system; 3: Discharging system; 4: Graphene film deposition area; 5: Material transfer guide; 6: High-purity copper target; 7: Copper film deposition area ;8: Graphene/copper composite.

Figure 2 is a physical photo of the graphene/copper composite material prepared in Example 6 of the present invention.

Figure 3 is a microstructure photograph of the graphene/copper composite material prepared in Example 6 of the present invention.

Detailed ways

The present invention will be described in detail below with reference to examples, but the protection scope of the present invention is not limited to the following examples.

Referring to Figure 1, an embodiment of the present invention provides an equipment for preparing graphene/copper composite materials, including a CVD deposition system 1 and a PVD deposition system 2; in the CVD deposition system 1, a chemical vapor deposition process is used to prepare the graphene/copper composite material on the surface of the rolled copper foil. Graphene film is used to make a copper/graphene material; in the PVD deposition system 2, a high-purity sputtering copper target is used as the material, and a physical vapor deposition process is used to deposit a copper film on the surface of the copper/graphene material to make Cu /C/Cu material; then in the CVD deposition system 2, a chemical vapor deposition process is used to prepare a graphene film on the surface of the Cu/C/Cu material to make a Cu/C/Cu/C composite material; in the PVD deposition system, Using a high-purity sputtering copper target as the material, a physical vapor deposition process is used to deposit a copper film on the surface of the Cu/C/Cu/C composite material to obtain a Cu/C/Cu/C/Cu composite material; repeat the above chemical vapor deposition process deposition process and physical vapor deposition process until a graphene/copper composite material 8 with a multi-layer structure is produced.

Further, the CVD deposition system 1 includes a graphene film deposition area 4, which uses a chemical vapor deposition process to perform chemical vapor deposition.

Further, the PVD deposition system 2 includes a copper thin film deposition area 7, which uses a high-purity sputtering copper target 6 as a material and uses a physical vapor deposition process to deposit a copper thin film.

Furthermore, the above-mentioned equipment also includes a discharging system 3 for transporting out the produced graphene/copper composite material with a multi-layer structure.

Further, the above equipment also includes a material transfer guide 5 for transferring materials (copper/graphene materials, Cu/C/Cu/C composite materials, Cu/C/Cu/C/Cu composite materials, etc.) in the CVD deposition system 1 and the PVD deposition system 2, and transport the produced graphene/copper composite material 8 with a multi-layer structure to the discharging system 3, or further transport it from the discharging system 3.

Further, the CVD deposition system 1 and the PVD deposition system 2 are in the same chamber. This can avoid the introduction of impurity elements and damage by mechanical stress during the transfer process of the graphene film, ensuring the integrity and uniformity of the graphene film in the copper matrix.

The graphene/copper composite materials of the following examples can be prepared using the equipment shown in Figure 1.

The preparation method of graphene/copper composite materials in the following examples is:

The following rolled copper foil has been pre-treated in advance to remove the oxide layer and ensure the cleanliness of the copper foil surface.

Step A: Take the rolled copper foil (the thickness of the copper foil is 10 μm), use methane as the carbon source, and use the CVD process to prepare a graphene film on the surface of the copper foil to obtain a copper/graphene material; for the specific process, see Table 1;

Step B: Take a high-purity sputtering copper target and use the PVD process to deposit a copper film on the surface of the copper/graphene material prepared in step A. The thickness of the copper film and the target power density are shown in Table 1 below; Cu/C/Cu/ composite materials;

Step C: Repeat the CVD process of step A, deposit a graphene film on the surface of the Cu/C/Cu material prepared in step B, and obtain a Cu/C/Cu/C composite material;

Step D: Repeat the PVD process of step B, deposit a copper film on the surface of the Cu/C/Cu/C material prepared in step C, and obtain a Cu/C/Cu/C/Cu composite material;

Step E: Repeat the PVD and CVD processes to finally obtain a graphene/copper composite material with a multi-layer structure.

After further processing, it is made into 100 (length) mm × 100 (width) mm × 2 (height) mm.

Table 1 lists the process parameters and product performance parameters of Examples 1-13.

Figure 2 is a photo of the graphene/copper composite material prepared in Example 6 and Example 7.

Figure 3 is a microstructure photograph of the graphene/copper composite material prepared in Example 6.

Experimental example

The prepared graphene/copper composite material was applied to a flat-panel transformer. The test results are shown in Table 1.

The results of Example 1 and Example 3 can show that after adding graphene, the electrical properties of the copper-based composite material are improved from 100% IACS to 108 IACS. The application verification results show that the temperature rise is reduced and the efficiency is improved.

Comparison between Example 3 and Example 13 found that after the number of graphene layers exceeds 5, the properties of graphene change and will exist in the copper matrix in the form of free carbon, which is equivalent to the existence of impurity elements, thereby producing Lattice defects, on the contrary, inhibit the improvement of electrical conductivity.

Comparative results of Examples 9, 10, and 11 show that as the purity of raw materials increases, the electrical properties improve;

The results of Examples 5, 6, and 7 show that increasing the target power can increase the density of the sputtered copper film, improve the composite effect of copper and graphene, and improve the strength and mechanical properties of the copper-based composite material. The impact on electrical performance is not significant.

The thermal conductivity test is conducted in accordance with GB/T22588-2008; the tensile strength test is conducted in accordance with GB/T228.1-2010; the electrical conductivity test is conducted in accordance with T/CSTM 00591-2022; the efficiency test is conducted in accordance with "GB/18613-2016 Small and Medium-sized Three "Energy efficiency limit value and energy efficiency grade of asynchronous motor"; skin depth test conditions: 100KHz, copper surface temperature 20℃.

Test results show that compared with pure copper, the efficiency is increased by 3.4% and the skin depth is increased by 30%.

Although the present invention has been described in detail with general descriptions and specific embodiments above, it is obvious to those skilled in the art that some modifications or improvements can be made based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Industrial applicability

The invention provides a method for preparing a graphene/copper composite material that combines physical vapor deposition and chemical vapor deposition. The method first uses CVD to deposit a layer of graphene material on the surface of the copper foil, uses PVD to deposit a layer of copper material on the surface of the graphene material, and then performs CVD to deposit the graphene material on the surface of the deposited copper material. Repeated deposition in this way obtains a layer with multiple properties. Layer-structured graphene/copper composites. The material is composed of pure copper and graphene. The tensile strength of the composite material is ≥200MPa, which is at the same level as pure copper. Its conductivity is ≥110% IACS, which is 10% higher than that of pure copper. Above; the skin depth is increased by 30% compared to pure copper. The material can replace traditional copper or silver materials and be used in supercapacitors or motor drives to improve efficiency and reduce temperature rise, and has good economic value and application prospects.

Claims (10)

1. A preparation method of graphene/copper composite material, characterized in that it includes:

   1) Provide rolled copper foil; use a chemical vapor deposition process to prepare a graphene film on the surface of the rolled copper foil to make a copper/graphene material;

   2) Using a high-purity sputtering copper target as the material, a physical vapor deposition process is used to deposit a copper film on the surface of the copper/graphene material to make a Cu/C/Cu material;

   3) Use a chemical vapor deposition process to prepare a graphene film on the surface of the Cu/C/Cu material to make a Cu/C/Cu/C composite material;

   4) Use a high-purity sputtering copper target as the material and use a physical vapor deposition process to deposit a copper film on the surface of the Cu/C/Cu/C composite material to obtain a Cu/C/Cu/C/Cu composite material;

   5) Continue to repeat steps 3) and 4) to make a graphene/copper composite material with a multi-layer structure.
2. The preparation method of graphene/copper composite material according to claim 1, characterized in that the thickness of the rolled copper foil in step 1) is between 8-25 μm; and/or the purity of the copper material used is ≥99.9%, Optional 99.9%-99.9999%.
3. The preparation method of graphene/copper composite material according to claim 1 or 2, characterized in that the carbon source used in the chemical vapor deposition is methane, ethylene, acetylene; and/or the temperature of the chemical vapor deposition is 950 -1000℃.
4. The method for preparing a graphene/copper composite material according to any one of claims 1 to 3, characterized in that the number of graphene thin films prepared by each chemical vapor deposition is 1 to 5 layers.
5. The preparation method of graphene/copper composite material according to any one of claims 1 to 4, characterized in that the thickness of the copper film prepared by physical vapor deposition each time is 1-15 μm; and/or,

   The background vacuum of each physical vapor deposition reaches 5.5×10 ^-3 Pa or above, and/or the target power density is 1-10W/cm ² ; and/or,

   The target current of the physical vapor deposition is 5-20A; and/or,

   The temperature of the physical vapor deposition is below 500°C.
6. The preparation method of graphene/copper composite material according to any one of claims 1-5, characterized in that the total number of layers of the graphene/copper composite material with a multi-layer structure is 10-1000 layers.
7. The method for preparing a graphene/copper composite material according to any one of claims 1 to 6, characterized in that in the preparation method, the operation of preparing the copper film and the operation of preparing the graphene film are performed in the same chamber.
8. A graphene/copper composite material with a multi-layer structure, characterized in that it is prepared by the method described in any one of claims 1-7.
9. An equipment for preparing graphene/copper composite materials, characterized by including a CVD deposition system and a PVD deposition system;

   In the CVD deposition system, a chemical vapor deposition process is used to prepare a graphene film on the surface of the rolled copper foil to produce a copper/graphene material;

   In the PVD deposition system, a high-purity sputtering copper target is used as the material, and a physical vapor deposition process is used to deposit a copper film on the surface of the copper/graphene material to make a Cu/C/Cu material;

   Then in the CVD deposition system, a chemical vapor deposition process is used to prepare a graphene film on the surface of the Cu/C/Cu material to make a Cu/C/Cu/C composite material;

   In the PVD deposition system, a high-purity sputtering copper target is used as the material, and a physical vapor deposition process is used to deposit a copper film on the surface of the Cu/C/Cu/C composite material to obtain Cu/C/Cu/C/Cu composite materials;

   Repeat the above chemical vapor deposition process and physical vapor deposition process until a graphene/copper composite material with a multi-layer structure is produced.
10. The equipment according to claim 9, characterized in that the CVD deposition system and the PVD deposition system are in the same chamber; and/or,

    The equipment also includes a discharging system for transporting out the graphene/copper composite material with a multi-layer structure.

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