A strained copper-graphene composite material and preparation method thereof

Abstract

The present invention relates to the technical field of metal-based composite materials, and in particular to a strained copper-graphene composite material and a preparation method thereof. The preparation method comprises: dispersing graphene in a parallel and oriented manner in a copper matrix to form a solid sample; first pressurizing and heating the solid sample, and then keeping the temperature and pressure; then cooling it to below 100°C at a rate of 2-10°C / s, and then unloading the pressure at a rate of 0.5-5MPa / s to obtain a strained copper-graphene composite material. The present invention generates strained copper in the copper-based graphene composite material by controlling matching cooling and unloading rates, thereby significantly improving the mechanical properties, thermal conductivity, and electrical conductivity of the copper-based graphene composite material. The present invention provides a new material design concept and engineering technology route for the preparation of high-strength, high-conductivity copper-based composite materials.

Description

Technical Field

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

[0002] Copper is a key nonferrous metal, one of the first discovered and used by humans. Due to its excellent electrical conductivity, heat transfer, ductility, strong tensile strength, and corrosion resistance, it is widely used in the power industry, machinery manufacturing, and defense industry. Furthermore, copper's abundant reserves and high recycling rate make it relatively low-cost and suitable for a wide range of applications.

[0003] Although copper's electrical conductivity (5.8 × 10^7 S / m in the International Annealed Copper Standard, 100% IACS) is already quite high, there are still ways to further improve its performance. Here are some possible approaches:

[0004] (1) Purification: By improving the purity of copper, the effects of impurities and grain boundaries on electrical conductivity can be reduced. Purification methods can include improvements in refining and smelting technology, as well as the use of higher purity raw materials.

[0005] (2) Alloying: The electrical conductivity of copper can be improved by adding appropriate alloying elements such as tin, nickel, zirconium, etc. These alloying elements can change the crystal structure and electronic structure of copper, thereby improving electrical conductivity.

[0006] (3) Pressing and deformation treatment: Through pressing and deformation treatment, the crystal structure and grain boundary arrangement of copper can be changed, thereby improving its conductivity. These methods can include cold working, extrusion, rolling and stretching.

[0007] (4) Conductive coating: By coating the copper surface with conductive materials such as silver, gold, copper-nickel alloy, etc., its conductivity can be improved. This method can increase the surface conductivity while maintaining the basic properties of copper. It should be noted that although these methods may improve the conductivity of copper, factors such as cost, feasibility and performance requirements need to be comprehensively considered in practical applications. In addition, continuous scientific research and technological innovation may introduce new methods and materials to further improve the conductivity of copper and promote the development of the field of conductive materials. In recent years, research on the introduction of carbon material reinforcements represented by graphene into copper matrix has gradually emerged. Its unique structure gives it high strength (tensile strength ~ 130GPa), high modulus (elastic modulus ~ 1TPa), high conductivity (electron mobility ~ 2×10 5 cm 2 ·V -1 ·s -1 ) characteristics, providing an opportunity for copper-based composite materials to achieve higher electrical conductivity while ensuring strength.

[0008] Many preparation processes for copper-based graphene composite materials are disclosed in the prior art. However, these preparation processes are all proposed to improve a single property among the mechanical properties, electrical conductivity or thermal conductivity of the composite materials. For example, the preparation process disclosed in CN110079785A improves the electrical conductivity of the copper-based graphene composite material; the preparation process disclosed in CN113716552A improves the thermal conductivity of the copper-based graphene composite material.

[0009] How to provide a new and simple method for preparing copper-based graphene composite materials so that the copper-based graphene composite materials simultaneously have excellent mechanical properties, electrical conductivity, thermal conductivity and other properties has always been the common pursuit of researchers in this field. Summary of the Invention

[0010] In order to solve the above technical problems, the present invention is proposed.

[0011] First, the present invention provides a method for preparing a strained copper-graphene composite material, comprising:

[0012] Graphene is dispersed in a parallel and oriented manner in a copper matrix to form a solid sample;

[0013] The solid sample is first pressurized and heated, and then kept at the same temperature and pressure;

[0014] The temperature is then lowered to below 100° C. at a rate of 2-10° C. / s, and then the pressure is released at a rate of 0.5-5 MPa / s to obtain the strained copper-graphene composite material.

[0015] The present invention finds that by controlling the cooling and pressure relief rate, the difference in mechanical properties between graphene and the copper matrix can be utilized, and the parallel distributed graphene sheets are used as stress concentration points to induce 1nm-100nm lattice distortion during the deformation of the copper matrix on both sides of the graphene. Compared with unstrained copper, the strained copper is subjected to GPa-level pressure and has a smaller lattice spacing. Relative to the entire block, the strained copper provides a high-speed channel for electron transmission, reduces the lattice constant of copper, and increases the interaction between copper atoms, thereby significantly improving the electrical conductivity of the copper itself. At the same time, the presence of the lattice distortion zone forms a large residual stress, which greatly enhances the mechanical properties of the composite material.

[0016] When the cooling rate and the stress relief rate do not match, for example, if the cooling rate is too fast, the unevenness of the copper matrix structure will be greatly increased, and the conductivity and mechanical properties of the material will be poor after stress relief; if the cooling rate is too slow, it will not be conducive to the formation of lattice distortion during the stress relief stage, and the generation of strained copper cannot be successfully induced; if the stress relief rate is too fast, it will be detrimental to the maintenance of residual stress inside the material. If the stress relief rate is too slow, the residual stress inside the material will be too large, thereby affecting the formation process of strained copper, and ultimately leading to poor mechanical properties, thermal conductivity and electrical conductivity of the material.

[0017] Preferably, the temperature is lowered to below 100° C. at a rate of 5-8° C. / s, and then the pressure is released at a rate of 1-2 MPa / s to obtain the strained copper-graphene composite material.

[0018] When the cooling and pressure relief rate is controlled within the above range, the lattice distortion effect can be further enhanced, so that the electrical and thermal conductivity and mechanical properties of the composite material are further significantly improved.

[0019] Preferably, the temperature of the heat preservation and pressure preservation is above 700° C., and the pressure is above 100 MPa.

[0020] Preferably, during the pressurization process, the pressure is increased to above 100 MPa at a pressurization rate of 0.5-5 MPa / s; more preferably 4-5 MPa / s;

[0021] And / or, during the heating process, the temperature is raised to 300° C. at a heating rate of 2-10° C. / s, and then raised to above 700° C. at a heating rate of 10-20° C. / s and kept at this temperature and pressure.

[0022] When the above-mentioned heating and pressurizing scheme is adopted, the temperature and pressure conditions can better provide an interface driving force for the extension of graphene and copper foil. As the temperature and pressure are continuously applied, the graphene and the nearby copper matrix are both in a high-energy state. Then, the above-mentioned cooling and pressure relief conditions are adopted to better induce lattice distortion of atoms at the graphene-copper interface and form a pressure-maintaining state, thereby further improving the overall performance of the composite material.

[0023] In a specific implementation process, the heating and pressurizing, heat preservation and pressure maintenance, and cooling and pressure relief processes are performed under an inert atmosphere. The inert atmosphere includes but is not limited to at least one of nitrogen, argon, hydrogen, and vacuum atmosphere.

[0024] The purpose of the inert atmosphere is to prevent oxidation of copper during processing.

[0025] Preferably, the heat preservation and pressure preservation are for 0.5-5 hours, more preferably for 1-3 hours.

[0026] More preferably, the maximum pressure of the pressurization is 100-300 MPa.

[0027] In a specific implementation process, the equipment for adjusting the temperature and pressure includes but is not limited to a hot pressing sintering furnace, a hot isostatic pressing sintering furnace, and a spark plasma sintering furnace.

[0028] Preferably, the graphene sheets are distributed in parallel in the copper matrix, and the grain size of the graphene sheets is 10-200 μm.

[0029] Preferably, in a single-layer graphene sheet, the spacing between graphene sheets is less than 0.01 μm.

[0030] In a specific implementation process, the method of dispersing graphene in parallel in a copper matrix includes: selecting graphene copper foil grown by chemical vapor deposition for stacking and compounding, or liquid-phase spin-coating graphene sheets on copper foil and then stacking and compounding.

[0031] Preferably, the thickness of the copper matrix between parallel adjacent graphene sheets is 20-30 μm.

[0032] Preferably, the strained copper-graphene composite material contains 20-50 layers of parallel distributed graphene sheets.

[0033] Preferably, the graphene is graphene that has not been chemically modified.

[0034] Furthermore, the present invention provides a strained copper-graphene composite material, which is prepared by the preparation method in any of the above embodiments.

[0035] In the strained copper-graphene composite material of the present invention, the strained copper is distributed within a range of 1 nm to 1 μm around the graphene layer, and the rest is a strain-free copper matrix.

[0036] In the strained copper-graphene composite material of the present invention, the crystal orientation of the copper matrix perpendicular to the direction of the graphene sheet is (111).

[0037] Furthermore, the present invention provides applications of the strained copper-graphene composite material in the fields of electricity, electronics, and machinery industries.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The present invention generates strained copper in a copper-based graphene composite material by controlling matching cooling and stress-relieving rates, thereby significantly improving the mechanical, thermal, and electrical conductivity of the copper-based graphene composite material. The preparation process of the present invention is simple and effective, improving the mechanical, thermal, and electrical conductivity of the copper-based graphene composite material, and is readily applicable for industrial scale-up. This invention provides a new material design approach and engineering technology for the preparation of high-strength, high-conductivity copper-based composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is the Raman area scan image and single spectrum of the high-quality graphene film grown on the copper foil in Example 1.

[0041] Figure 2 Schematic diagram of the structure of the strained copper-graphene composite material in Example 1.

[0042] Figure 3 This is a microscopic scanning electron microscope structure diagram of the copper / graphene interface of the strained copper-graphene composite material in Example 1. DETAILED DESCRIPTION

[0043] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0044] Where specific techniques or conditions are not specified in the examples, all methods were performed according to conventional methods, techniques or conditions described in literature in the field, or according to product specifications. Reagents and instruments used, for which the manufacturers are not specified, are conventional products that can be purchased through regular channels.

[0045] The graphene in the following examples is unmodified graphene prepared by chemical vapor deposition. The preparation method is referred to CN102275907A. Raman spectroscopy results show that the G peak and 2D peak are obvious, the D peak is relatively low, and the square resistance after transfer is 300-450 ohms / □.

[0046] Example 1

[0047] This embodiment provides a strained copper-graphene composite material, and the preparation method thereof is as follows:

[0048] (1) Using chemical vapor deposition, 100% graphene coverage was grown on a single surface of a 25 μm polycrystalline rolled copper foil with a sheet diameter of 10 μm. 40 layers of graphene copper foil were stacked to form a 1 mm thick solid sample. The Raman area scan and single spectrum of the graphene film grown on the copper foil are shown in Figure 2. Figure 1 shown.

[0049] (2) Using a 2000T vacuum hot pressing sintering furnace in an atmosphere of 5% hydrogen in an argon-hydrogen mixture, the pressure was increased to 100MPa at a pressure rate of 4.5MPa / s, and then the temperature was increased to 300℃ at a heating rate of 5℃ / s, and then the temperature was increased to 850℃ at a heating rate of 14℃ / s and kept at this temperature for 2h.

[0050] (3) The temperature was lowered to 100°C at a rate of 6°C / s, and then the pressure was released at a rate of 1 MPa / s to obtain a strained copper-graphene composite material. The structural diagram is shown in FIG. Figure 2 As shown in the microscopic scanning electron microscope structure diagram Figure 3 shown.

[0051] Example 2

[0052] This embodiment provides a strained copper-graphene composite material, and the preparation method is different from that of Example 1 only in that:

[0053] (2) Pressurize to 100 MPa at a pressurization rate of 6 MPa / s.

[0054] Example 3

[0055] This embodiment provides a strained copper-graphene composite material, and the preparation method is different from that of Example 1 only in that:

[0056] (2) The temperature was raised to 300°C at a heating rate of 12°C / s, and then raised to 850°C at a heating rate of 22°C / s and kept at this temperature and pressure.

[0057] Example 4

[0058] This embodiment provides a strained copper-graphene composite material, and the preparation method is different from that of Example 1 only in that:

[0059] (3) The temperature was lowered to 100°C at a rate of 2°C / s, and then the pressure was released at a rate of 0.5 MPa / s to obtain a strained copper-graphene composite material.

[0060] Example 5

[0061] This embodiment provides a strained copper-graphene composite material, and the preparation method is different from that of Example 1 only in that:

[0062] (3) The temperature was lowered to 100°C at a rate of 10°C / s, and then the pressure was released at a rate of 5 MPa / s to obtain a strained copper-graphene composite material.

[0063] Comparative Example 1

[0064] This comparative example provides a copper-based graphene composite material, and the preparation method is different from that of Example 1 only in that:

[0065] (3) The temperature was lowered to 100°C at a rate of 1°C / s, and then the pressure was released at a rate of 0.2 MPa / s to obtain a copper-based graphene composite material.

[0066] Comparative Example 2

[0067] This comparative example provides a copper-based graphene composite material, and the preparation method is different from that of Example 1 only in that:

[0068] (3) The temperature was lowered to 100°C at a rate of 15°C / s, and then the pressure was released at a rate of 10 MPa / s to obtain a copper-based graphene composite material.

[0069] Test example

[0070] The electrical conductivity, tensile strength, ductility and thermal conductivity of the composite materials prepared in the above examples and comparative examples were tested.

[0071] The electrical conductivity test was conducted in accordance with the group standard "Measurement of Electrical Conductivity of Graphene-Copper Thin Film Materials by the Van der Pauw Method" (T / CSTM 00591-2022). The tensile strength test was conducted in accordance with the national standard "Tensile Test of Metallic Materials" (GB / T 228.1-2010). The ductility test was conducted in accordance with the national standard "Tensile Test of Metallic Materials" (GB / T 228.1-2010). The thermal conductivity test was conducted in accordance with the national standard "Method for Determination of Thermal Conductivity of Metals at High Temperature" (GB / T 3651-2008).

[0072] The test results are shown in Table 1.

[0073] Table 1

[0074]

[0075]

[0076] 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 various embodiments of the present invention.

Claims

1. A method for preparing a strained copper-graphene composite material, characterized in that: include: Graphene is dispersed in a copper matrix in a parallel and oriented manner to form a solid sample; wherein the graphene sheets are distributed in parallel in the copper matrix, and the solid sample contains 20-50 layers of parallel graphene sheets; the thickness of the copper matrix between adjacent parallel graphene sheets is 20-30 μm; and the grain size of the graphene sheets is 10-200 μm; The solid sample is first pressurized and heated, and then kept warm and pressurized; the pressurization and heating, and then the heat preservation and pressure preservation are pressurized to above 100 MPa at a pressurization rate of 4-5 MPa / s, then heated to 300° C. at a heating rate of 2-10° C. / s, and then heated to above 700° C. at a heating rate of 10-20° C. / s, and kept warm and pressurized; The temperature is then lowered to below 100° C. at a rate of 5-8° C. / s, and then the pressure is released at a rate of 1-2 MPa / s to obtain the strained copper-graphene composite material.

2. The preparation method according to claim 1, characterized in that In a single-layer graphene sheet, the spacing between graphene sheets is less than 0.01 μm.

3. The preparation method according to claim 1, characterized in that The graphene is graphene that has not been chemically modified.

4. A strained copper-graphene composite material, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 3.

5. The strained copper-graphene composite material according to claim 4, characterized in that: The crystal orientation of the copper matrix perpendicular to the graphene sheet is (111); the strained copper is distributed within the range of 1nm-1μm around the graphene sheet.

6. Application of the strained copper-graphene composite material according to claim 4 or 5 in the fields of electric power, electronics and machinery industries.

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