A method for preparing graphene-nanotwinned copper composite material

Abstract

This invention relates to the technical field of graphene composite material preparation, specifically to a method for preparing a graphene-nanotwinned copper composite material, which is prepared using a pulsed composite electrodeposition process, including the following steps: (1) preparing a copper sulfate electroplating solution containing a brightener, a leveling agent, and a dispersant, and uniformly dispersing graphene in the electroplating solution to form the final composite plating solution; (2) using an inert electrode as the cathode and a copper-phosphorus plate as the anode, placing the cathode and anode in the composite plating solution, and performing pulsed electrodeposition to obtain a composite material with a gradient structure of copper grains as the matrix and graphene as the reinforcing phase. The graphene / gradient nanotwinned copper composite material prepared by the method of this invention has the characteristics of good graphene dispersion, fine matrix twin layers, and excellent composite material hardness and thermal conductivity. This method is suitable for large-scale industrial applications.

Description

Technical Field

[0001] This invention relates to the technical field of graphene composite material preparation, specifically to a method for preparing a graphene-nanotwinned copper composite material. Background Technology

[0002] Graphene is a material composed of carbon atoms arranged in sp... 2 Graphene is a two-dimensional material composed of hexagonal, honeycomb-like, ordered structures formed by hybridization. Since its discovery, graphene has attracted considerable attention from researchers. It possesses excellent thermal and electrical conductivity, and its theoretical specific surface area is as high as 2630 m². 2 / g, with a carrier mobility of approximately 15000 cm⁻¹ at room temperature. 2 / (V·s), with a thermal conductivity as high as 5300 W / mK and as low as 10 -6 Graphene has a resistivity of Ω·cm. It also possesses extremely high strength and Young's modulus, with a strength of up to 130 GPa, making it the strongest known material.

[0003] Copper-based composite materials have experienced rapid growth in the past decade due to their excellent thermal conductivity, good mechanical properties, and higher electrical conductivity compared to other materials. These advantages have led to their widespread application in the electronics industry. Pure copper foil with a twinned structure, prepared by electro-pulse deposition, can achieve a yield strength of up to 900 MPa and a tensile strength of up to 1068 MPa, with an electrical conductivity reaching 96.9 ± 1.1% of the international standard for annealed copper. While adding oxides and carbides to the copper matrix as reinforcing materials can improve its mechanical properties, their electrical and thermal properties are insufficient to meet the requirements of electronic components. Therefore, novel carbon derivatives such as carbon nanotubes, carbon nanofibers, and graphene, due to their excellent electrical, thermal, and mechanical properties, are considered ideal reinforcing materials for the matrix, attracting widespread attention from the academic community and resulting in numerous related commercial experiments.

[0004] Currently, copper-graphene composites are typically prepared using powder metallurgy. However, powder metallurgy struggles to achieve nanotwinned copper structures and good graphene dispersion within the matrix. Electrodeposition can produce nanotwinned copper structures, but its drawback lies in the requirement to set the voltage based on the desired current density. During electrodeposition, the resistance of the plating solution and the cathode changes, making it impossible to maintain a constant pulsed current density throughout the entire process under pulsed conditions. Therefore, a special process is needed to achieve continuous pulsed current electrodeposition for preparing graphene-nanotwinned copper composites. Furthermore, adding graphene to the electrodeposition solution can lead to agglomeration, uneven deposition, and decreased composite density. This study addresses these issues by improving the plating solution formulation and employing ultrasonic homogenization technology, achieving better bonding at the copper-carbon interface. Traditional DC electrodeposition suffers from ablation at high current densities. This patent utilizes an adjusted electrodeposition formulation and improved apparatus to achieve electrodeposition at high current densities, further enhancing the density of the electrodeposited composite material.

[0005] Based on the above problems, this patent proposes a method for preparing a graphene-nanotwinned copper composite material with high hardness and high thermal conductivity by solving the problems of obtaining a high-density twinned copper matrix and dispersing and compositing graphene. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing graphene-nanotwinned copper composite material. The obtained graphene / gradient nanotwinned copper composite material has the characteristics of good graphene dispersion, fine matrix twin layers, and excellent composite material hardness and thermal conductivity. This method is suitable for large-scale industrial applications.

[0007] The solution adopted by this invention to achieve its objective is: a method for preparing graphene-nanotwinned copper composite material, which is prepared using a pulsed composite electrodeposition process, including the following steps:

[0008] (1) Prepare a copper sulfate electroplating solution containing brightener, leveling agent and dispersant, and uniformly disperse graphene in the electroplating solution to form the final composite plating solution;

[0009] (2) An inert electrode is used as the cathode and a copper-phosphorus plate is used as the anode. The cathode and anode are placed in a composite plating solution and pulse electrodeposition is performed to obtain a composite material with a gradient structure of copper grains as the matrix and graphene as the reinforcing phase.

[0010] Preferably, in step (1), the copper sulfate electroplating solution contains CuSO4 and additives, wherein the concentration of CuSO4 in the composite plating solution is 0.1-1M, and the additives include polyethylene glycol, sodium dodecyl sulfate and NaCl, wherein the concentration of polyethylene glycol in the composite plating solution is 0.05-0.1g / L, the concentration of sodium dodecyl sulfate is 0.05-0.1g / L, and the concentration of NaCl is 0-100mg / L.

[0011] Preferably, in step (1), the brightener is a polysulfide organic sulfonate, the leveling agent is a mercapto heterocyclic compound, the dispersant is a variety of surfactants, and the concentration of the brightener in the composite plating solution is 0.01-0.1 g / L, the concentration of the leveling agent is 0.01-0.1 g / L, and the concentration of the dispersant is 0.01-0.1 g / L.

[0012] Preferably, in step (1), the composite plating solution further includes a cuprous ion oxidant, wherein the cuprous ion oxidant is hydrogen peroxide with a concentration of 27.5-35 wt% and an addition amount of 1-10 mL / L.

[0013] This invention features a unique pulse electrodeposition plating solution formulation. Considering the need to disperse graphene and homogenize electrodeposition under high current density, the classic electroplating solution formulation is modified to adapt to the microstructure requirements of composite materials.

[0014] Preferably, in step (1), concentrated sulfuric acid is added to the composite plating solution until the pH of the electrodeposition solution is less than or equal to 1.

[0015] Preferably, in step (1), the graphene is a few-layer graphene sheet with 1 to 3 layers and a sheet diameter of 7 to 12 μm, and the concentration of graphene in the composite plating solution is less than 0.5 g / L.

[0016] Preferably, in step (2), the cathode is any one of stainless steel, graphite, platinum, and titanium. When stainless steel cathode is used, chemical nickel plating pretreatment is performed first. The anode is a copper-phosphorus plate with a phosphorus content of 0.035% to 0.07%. The ratio of the conductive surface area of ​​the anode to the conductive surface area of ​​the cathode is 20 to 5:1. The distance between the cathode and the anode is 1 to 6 cm.

[0017] Preferably, in step (2), the pulse electrodeposition temperature is 5~30℃, and a constant current is used during the pulse electrodeposition process, with the current density set to 20~800mA / cm². 2 The electrodeposition time is 0.5~60h, the pulse frequency is 0.1-0.3 seconds of low conduction time and 1-2 seconds of long disconnection time.

[0018] Preferably, in step (2), the composite plating solution is continuously stirred during the pulse electrodeposition process at a rate of 200~1000 rpm.

[0019] This invention achieves a graphene composite material with a fine nanotwin structure by precisely controlling the current density and stirring rate during the electrodeposition process.

[0020] Preferably, in step (2), ultrasonic oscillation is continuously performed during the pulse electrodeposition process, and the ultrasonic frequency is 10-40KHZ.

[0021] This invention utilizes ultrasonic oscillation technology and variable-speed electromagnetic stirring technology during the electrodeposition process to enhance the reinforcing effect of graphene as a reinforcement in composite materials and mitigate the adverse effects of graphene agglomeration on the material.

[0022] The principle of this invention is as follows:

[0023] This invention utilizes the principle of composite electrodeposition, where graphene and copper ions in the electroplating solution are co-deposited on the cathode. An innovative dispersant is added to the plating solution, and ultrasonic homogenization technology is employed to achieve uniform dispersion of graphene in the material, reducing the generation of cuprous oxide ion slag. Dynamic voltage compensation is used to accurately control the current density, resulting in a uniform, dense, and stable composite material.

[0024] The present invention has the following advantages and beneficial effects:

[0025] The preparation method of this invention has a simple process flow, good scalability, and is suitable for industrial production. It uses simple raw materials, has a high sample qualification rate, and the obtained graphene / gradient nanotwinned copper composite material exhibits good graphene dispersion, fine matrix twin layers, and excellent composite material hardness and thermal conductivity.

[0026] The graphene / gradient nanotwinned copper composite material prepared by this invention has a gradient twinned structure with a twin interlayer spacing between 50-100 nm. At the interface, there is a regular arrangement of the (111) crystal plane orientation of copper crystals and the (100) crystal plane orientation of graphene. The hardness can reach up to 3.5 GPa, and the thermal conductivity is significantly higher than that of pure copper. Attached Figure Description

[0027] Figure 1 This is a regional scanning electron microscope image (GD) of the graphene / twinned copper composite material prepared by adding 0.1 g / L graphene to the plating solution and at a current density of 300 mA / cm² in Example 1 of the present invention.

[0028] Figure 2These are magnified scanning electron microscope (SEM) images of different locations (near substrate region, intermediate region, and surface region) of the graphene / twinned copper composite material prepared in Example 1 of this invention by adding 0.1 g / L graphene to the plating solution and using a current density of 300 mA / cm². (a) 0.1 g near substrate side, (b) 0.1 g intermediate side, (c) 0.1 g surface side;

[0029] Figure 3 This is a TEM image of a sample with 0.1 g / L graphene added to the plating solution in this embodiment;

[0030] Figure 4 A comparison of the impact pit depth and hardness of coarse copper, electrodeposited pure copper (NO), and 0.1 g / L graphene plating solution sample (0.1).

[0031] Figure 5 A comparison of the thermal conductivity of pure copper (Cu) and a 0.1 g / L graphene plating solution sample (0.1 g / L).

[0032] Figure 6 The following are scanning electron microscope images of graphene / twinned copper composite materials prepared at a current density of 300 mA per square centimeter for comparison between the sample without graphene and the sample with 0.3 g / L graphene added in Example 3. (a) and (b) are the sample without graphene, and (c) and (d) are the sample with 0.3 g / L graphene added at a high rotation speed of 600 r / min.

[0033] Figure 7 The image shows a scanning electron microscope (SEM) image of the graphene / twinned copper composite material prepared in Example 3 by adding 0.3 g / L graphene to the plating solution and stirring at a current density of 300 mA / cm² and a stirring rate of 200 r / min.

[0034] Figure 8 The hardness values ​​(points in the figure) of samples prepared using the present invention at concentrations of 0.1 g / L, 0.2 g / L, 0.3 g / L and without graphene are compared with the theoretical hardness values ​​of pure copper at different grain sizes (slanted lines in the figure).

[0035] Figure 9 The images show the Raman spectra of the deposited samples under laser microscopy confocal mode. From top to bottom, they are the Raman peak spectra of the 0.1 g / L and 0.3 g / L samples without graphene, and the graphene powder sample. Detailed Implementation

[0036] To better understand the present invention, the following embodiments are further illustrations of the present invention, but the content of the present invention is not limited to the following embodiments.

[0037] In the examples described below, 0.1, 0.2, and 0.3 represent the concentrations of graphene added to the plating solution as 0.1 g / L, 0.2 g / L, and 0.3 g / L, respectively.

[0038] Example 1

[0039] A method for preparing a graphene-nanotwinned copper composite material includes the following steps;

[0040] (1) A flat stainless steel sheet with an effective deposition area of ​​2*2cm is obtained by wire cutting. The deposition side is polished with 2000-grit sandpaper, and the cathode side facing away from the anode is sealed with insulating tape.

[0041] (2) A copper-phosphorus plate measuring 8*9cm was obtained by wire cutting and used as the anode. The side of the anode facing away from the cathode was sealed with insulating tape and wrapped with polypropylene cloth or other slag-blocking filter cloth for later use;

[0042] (3) The cathode is first immersed in the degreasing solution for 30 minutes at room temperature, and then placed in the activation solution for 10 minutes. After observing that bubbles are generated on its surface and the color changes, it is taken out and placed in the electroless nickel plating solution at 70°C for at least 30 minutes. The bubbles generated in the nickel layer during the electroless nickel plating process are eliminated by using the degassing mode of the ultrasonic cleaner to prevent the formation of holes caused by bubble rupture in the final deposited nickel plating layer.

[0043] (4) The electroplating solution was prepared using deionized water, wherein the graphene was 0.1 g / L, polyethylene glycol was 0.05 g / L, sodium dodecyl sulfate was 0.1 g / L, anhydrous CuSO4 powder was 128 g / L, NaCl was 80 mg, 2-mercaptobenzimidazole was 0.0005 g / L, 1-2-ethylidene thiourea was 0.0005 g / L, sodium polydithiopropane sulfonate (SPS) was 0.01 g / L, hydrogen peroxide (purity 30%) was 3 mg / L, and polyvinylpyrrolidone (PVP) was 15 mg / L;

[0044] (5) Before electroplating, read the pH value of the solution with a pH tester and add concentrated sulfuric acid until the pH is 1;

[0045] (6) Place the cathode and anode plates in the plating solution and connect the circuit. Open the program for manually adjusting the electroplating current density, set the current density to 300 mA per square centimeter, and manually adjust the pulse voltage to a suitable value between 0-20V.

[0046] (7) Adjust the DC power supply of the stirring motor to a constant current mode and adjust the current so that the stirring speed reaches 400 r / min;

[0047] (8) After 60 hours of electroplating, the sample attached to the cathode surface was removed, ultrasonically cleaned in distilled water, rinsed with alcohol and dried to obtain graphene / twinned copper composite material.

[0048] Figure 1 This is a regional scanning electron microscope image (GD) of the graphene / twinned copper composite material prepared in this example by adding 0.1 g / L graphene to the plating solution and at a current density of 300 mA / cm². Figure 2 These are magnified scanning electron microscope (SEM) images of different locations (near substrate region, intermediate region, and surface region) of the graphene / twinned copper composite material prepared in this embodiment by adding 0.1 g / L graphene to the plating solution and using a current density of 300 mA / cm². (a) 0.1 g near substrate side, (b) 0.1 g intermediate side, and (c) 0.1 g surface side. Figure 1 and Figure 2 In the substrate, influenced by the deposited electroless nickel plating layer, the initial crystal grains are relatively small, ranging from several hundred nanometers in size. Graphene sheets are incorporated into the crystals, subsequently growing into columnar twins with consistent orientation. The twin sheet layers are parallel to the growth plane and perpendicular to the grain growth direction. Graphene is distributed at grain boundaries and within the grains. Fine equiaxed crystal structures appear on the surface.

[0049] Figure 3 The image shows a TEM image of a sample with 0.1 g / L graphene added to the plating solution in this embodiment. The image shows a high-density columnar twin structure at the 20-micrometer and thicker sections of the composite material, with a twin layer spacing of up to 50 nm and a total twin layer thickness of up to 1 micrometer. At the interface of the composite material, the graphene (100) and copper (111) crystal planes are connected.

[0050] Figure 4 The comparison of impact pit depth and hardness of samples (0.1 g / L graphene plating solution) for coarse copper, electrodeposited pure copper (NO), and coarse copper (coarse copper), shows that the hardness of the composite material is between 2.5 and 3.5 GPa, which is much higher than the strengthening effect limit that fine grains can provide. This indicates that graphene contributes 1 GPa or more to the hardness of the composite material and has good impact resistance.

[0051] Figure 5 The thermal conductivity of pure copper (Cu) and 0.1 g / L graphene plating solution (0.1) is compared. As can be seen from the figure, the test results of the thermal conductivity of graphene-nanotwinned copper composite material are higher than those of coarse-grained pure copper.

[0052] Example 2

[0053] Add 0.2 g / L of graphene to the electrodeposition solution, stir at 600 rpm, and follow the same steps as in Example 1.

[0054] Example 3

[0055] Add 0.3 g / L of graphene to the electrodeposition solution, stir at 200 rpm, and follow the same steps as in Example 1.

[0056] Example 4

[0057] Add 0.4 g / L of graphene to the electrodeposition solution, stir at 200 rpm, and follow the same steps as in Example 1.

[0058] Comparative Example

[0059] No graphene was added to the electrodeposition solution, and the other steps were the same as in Example 1.

[0060] Figure 6 The following are scanning electron microscope images of graphene / twinned copper composite materials prepared at a current density of 300 mA per square centimeter for comparison between the sample without graphene and the sample with 0.3 g / L graphene added in Example 3. (a) and (b) are the sample without graphene, and (c) and (d) are the sample with 0.3 g / L graphene added at a high rotation speed of 600 r / min.

[0061] Figure 7 The image shows a scanning electron microscope (SEM) image of the graphene / twinned copper composite material prepared in Example 3 by adding 0.3 g / L graphene to the plating solution and stirring at a current density of 300 mA / cm² and a stirring rate of 200 r / min.

[0062] Combination Figure 1-4 The structural characteristics of the graphene-nanotwinned copper composite material prepared by this invention can be seen.

[0063] Figure 8 To compare the hardness values ​​(points in the figure) of the 0.1 g / L, 0.2 g / L, 0.3 g / L samples and the sample without graphene prepared using this invention with the theoretical hardness values ​​of pure copper at different grain sizes (slanted lines in the figure), it can be seen from the figure that the hardness value of the composite material sample with added graphene is much higher than that of pure copper material with the same structure. The contribution of graphene to hardness is as high as about 1.5 GPa.

[0064] Figure 9 The Raman spectra of the deposited samples under laser microscopy confocal mode are shown below. From top to bottom, they are the Raman peak spectra of the 0.1 g / L and 0.3 g / L samples without graphene, and the graphene powder sample. It can be seen from the figure that there are obvious graphene characteristic peaks in the composite material, proving that the pulsed composite electrodeposition technology can effectively realize the composite of twinned copper and graphene.

[0065] The above description is merely a preferred embodiment of the present invention, and should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing a graphene-nanotwinned copper composite material, characterized in that, The process involves pulsed composite electrodeposition, including the following steps: (1) Prepare a copper sulfate electroplating solution containing brightener, leveling agent and dispersant, and uniformly disperse graphene in the electroplating solution to form the final composite plating solution; (2) An inert electrode is used as the cathode and a copper-phosphorus plate is used as the anode. The cathode and anode are placed in a composite plating solution and pulse electrodeposition is performed to obtain a composite material with a gradient structure of copper grains as the matrix and graphene as the reinforcing phase. In step (1), the copper sulfate electroplating solution contains CuSO4 and additives. The concentration of CuSO4 in the composite plating solution is 0.1-1M. The additives include polyethylene glycol, sodium dodecyl sulfate, and NaCl. The concentration of polyethylene glycol, sodium dodecyl sulfate, and NaCl in the composite plating solution is 0.05-0.1g / L, 0.05-0.1g / L, and 0-100mg / L. The brightener is a polysulfide organic sulfonate, the leveling agent is a mercapto heterocyclic compound, and the dispersant is various surfactants. The concentration of brightener, leveling agent, and dispersant in the composite plating solution is 0.01-0.1g / L. In step (2), the pulse electrodeposition temperature is 5~30℃, and a constant current is used during the pulse electrodeposition process, with the current density set to 20~800mA / cm². 2 The electrodeposition time is 0.5~60h, the pulse frequency is 0.1-0.3 seconds of low conduction time and 1-2 seconds of long disconnection time; the composite plating solution is continuously stirred during the pulse electrodeposition process at a rate of 200~1000rpm; and ultrasonic oscillation is continuously performed during the pulse electrodeposition process at an ultrasonic frequency of 10-40KHZ. The prepared graphene-nanotwinned copper composite material has a gradient twinned structure with a twin layer spacing between 50-100 nm. At the interface, there is an arrangement pattern in which the (111) crystal plane orientation of copper crystals and the (100) crystal plane orientation of graphene are connected.

2. The method for preparing the graphene-nanotwinned copper composite material according to claim 1, characterized in that: In step (1), the composite plating solution also includes a cuprous ion oxidant, which is hydrogen peroxide with a concentration of 27.5-35wt% and an addition amount of 1-10mL / L.

3. The method for preparing the graphene-nanotwinned copper composite material according to claim 1, characterized in that: In step (1), concentrated sulfuric acid is added to the composite plating solution until the pH of the electrodeposition solution is less than or equal to 1.

4. The method for preparing the graphene-nanotwinned copper composite material according to claim 1, characterized in that: In step (1), the graphene is a few-layer graphene sheet with 1 to 3 layers and a sheet diameter of 7 to 12 μm. The concentration of graphene in the composite plating solution is less than 0.5 g / L.

5. The method for preparing the graphene-nanotwinned copper composite material according to claim 1, characterized in that: In step (2), the cathode is any one of stainless steel, graphite, platinum, and titanium. When stainless steel cathode is used, chemical nickel plating pretreatment is performed first. The anode is a copper-phosphorus plate with a phosphorus content of 0.035% to 0.07%. The ratio of the conductive surface area of ​​the anode to the conductive surface area of ​​the cathode is 20 to 5:

1. The distance between the cathode and the anode is 1 to 6 cm.

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