Graphene copper batch production method

Abstract

This invention relates to the field of powder metallurgy technology and discloses a method for the mass production of graphene copper. The method comprises the following steps: S1. Micron-sized copper powder is placed in a high-temperature furnace and heat-treated under air or pure oxygen atmosphere to obtain pre-oxidized copper powder; S2. The pre-oxidized copper powder is mixed with a pore-forming agent and a volatile binder, pressed into a blank, and kept at a high-purity hydrogen atmosphere for 24 hours to obtain a three-dimensional interconnected porous pure copper framework; S3. The three-dimensional interconnected porous pure copper framework is pretreated under hydrogen at 850℃-1050℃, and a carbon source gas is introduced for the first vapor phase deposition; S4. The carbon source is stopped, and the framework is annealed in situ at a constant temperature in a pure hydrogen environment, followed by a second slow vapor phase deposition for 30-60 minutes using a carbon source to obtain a graphene-coated porous copper framework; S5. The graphene-coated porous copper framework is hot-pressed to densify, held under pressure, cooled to below 200℃, and demolded to obtain a graphene copper-based composite material. This invention features easily controllable process variables, high batch stability, and low production cost.

Description

Technical Field

[0001] This invention relates to the field of powder metallurgy technology, specifically to a method for the mass production of graphene copper. Background Technology

[0002] In recent years, with the rapid development of artificial intelligence, new energy, 5G communication and other fields, higher performance requirements and low loss standards have been put forward for conductive and thermally conductive materials. The electrical and thermal conductivity of traditional copper-based materials has gradually approached its physical limit, and existing alternatives have obvious shortcomings and cannot meet the stringent requirements of high-end application scenarios. Graphene, with its extremely high theoretical electrical and thermal conductivity as well as excellent physicochemical stability, is recognized as the ideal reinforcement for the next generation of high-performance copper-based composite materials. Currently, the mainstream preparation processes for graphene / copper-based composite materials mainly focus on achieving uniform dispersion of graphene, strengthening interfacial bonding, and promoting large-scale mass production. Existing representative processes include: (1) In-situ chemical vapor deposition: graphene is grown in situ on the surface of copper powder using methane and other carbon sources. This method has uniform dispersion and strong interfacial bonding, and is suitable for the preparation of high-end powders and high-performance components; (2) Wet chemical method (such as the reaction of graphene oxide with copper salt solution): nanoscale dispersion can be achieved, taking into account both mechanical and thermoelectric properties, and is suitable for precision electronic devices; (3) Electrochemical deposition: the process is relatively flexible and is mainly used to prepare ultra-thin coatings, which are suitable for surface coatings of electronic components and flexible devices. However, although the above methods can achieve good comprehensive performance, they generally have common problems such as high equipment requirements, complex process flow, and high preparation cost, which seriously restrict the large-scale industrial application of graphene / copper-based composite materials. Summary of the Invention

[0003] The purpose of this invention is to solve the above-mentioned problems by designing a method for the mass production of graphene copper.

[0004] This invention provides a method for the mass production of graphene copper, the method comprising the following steps: S1. Select micron-sized copper powder and place it in a high-temperature heating furnace at 200°C under air or pure oxygen atmosphere. Heat treatment at 500℃ for 0.5 seconds After 3 hours, pre-oxidized copper powder with a copper oxide / cuprous oxide shell on the surface is obtained; S2. Mix the pre-oxidized copper powder with the pore-forming agent and volatile binder, press it into a blank, and heat it at 700℃. Insulated at 900℃ in a high-purity hydrogen atmosphere for 2 hours A three-dimensional interconnected porous pure copper skeleton was obtained in 4 hours; S3. The three-dimensional interconnected porous pure copper framework is heated to 850℃. Pretreatment at 1050℃ under hydrogen gas followed by initial vapor deposition using carbon source gas. S4. Stop the carbon source and anneal in situ at a constant temperature in a pure hydrogen environment. Then introduce the carbon source again for a second slow vapor deposition for 30-60 minutes to obtain a graphene-coated porous copper framework. S5. The graphene-coated porous copper skeleton is hot-pressed and densified, then cooled under pressure to below 200°C and demolded to obtain the graphene-copper composite material.

[0005] Optionally, in the first implementation of the present invention, the copper powder particle size in step S1 is 5–500 μm, and the copper oxide / cuprous oxide shell thickness is 50–500 nm.

[0006] Optionally, in the second implementation of the present invention, step S2 specifically includes: The pre-oxidized copper powder is mixed with the pore-forming agent and volatile binder in a uniform ratio and then pressed into a porous precursor green body. The porous precursor green body is placed in a tube furnace and kept at a high-purity hydrogen atmosphere of 700℃-900℃ for 2-4 hours. During the high-temperature reduction process, the oxide layer on the surface of the copper powder is reduced in situ to nascent nano-copper active atoms. The active atoms of nascent nano-copper diffuse at the particle contact sites, forming a metallurgical bonding neck. After cooling in the furnace, a three-dimensional interconnected porous pure copper framework is obtained.

[0007] Optionally, in a third implementation of the present invention, in step S2, based on the mass of the pre-oxidized copper powder, the addition ratio of the pore-forming agent is 10 wt%, and the addition ratio of the volatile binder is 2 wt%, wherein the pore-forming agent is one or more of ammonium bicarbonate, urea, and sodium chloride, and the volatile binder is one or more of polyvinyl alcohol, polyethylene glycol, polymethyl methacrylate, and paraffin wax.

[0008] Optionally, in the fourth implementation of the present invention, the porosity of the three-dimensional porous pure copper framework prepared in step S2 is 35%. 65% of the average pore size is 10 μm Between 200μm, the internal pores exhibit a three-dimensional interconnected structure.

[0009] Optionally, in the fifth implementation of the present invention, the specific process of step S3 includes: The three-dimensional interconnected porous pure copper framework is placed in the high temperature constant temperature zone of the gas phase reaction sintering furnace. After evacuating the air, it is pretreated for 20-60 minutes under hydrogen protection at 850℃-1050℃ to remove adsorbed impurities on the surface of the three-dimensional interconnected porous pure copper framework and expose more highly active catalytic sites by thermal etching. Carbon source gas is introduced, and the first vapor deposition is carried out for 5-15 minutes under a deposition pressure of 50-500 Pa, so that carbon atoms nucleate and initially cover the surface of the three-dimensional interconnected porous pure copper framework.

[0010] Optionally, in the sixth implementation of the present invention, the flow ratio of carbon source gas to hydrogen during the first vapor phase deposition in step S3 is 1:5 to 1:10, and the flow ratio of carbon source gas to hydrogen during the second slow vapor phase deposition in step S4 is 1:15 to 1:25. The first vapor phase deposition and the second slow vapor phase deposition are connected by in-situ annealing with intermediate pure hydrogen.

[0011] Optionally, in the seventh implementation of the present invention, the carbon source gas is one or more of methane, ethylene, and acetylene.

[0012] Optionally, in the eighth implementation of the present invention, the specific process of step S5 includes: Graphene-coated porous copper skeletons are placed into high-temperature and high-pressure molds and heated to 750℃-1000℃ under vacuum or inert protective gas. After reaching the set temperature, apply a uniaxial directional pressure of 10-80MPa and maintain the temperature and pressure for 1-3 hours. Under the thermo-coupling effect of high temperature and high pressure, the graphene is embedded in the dense copper grain boundary. Under pressure-maintaining conditions, the material is cooled in the furnace to below 200°C to release pressure and demold, thus obtaining a graphene-copper-based composite material.

[0013] Optionally, in the ninth implementation of the present invention, the heating rate in step S5 is controlled at 3°C / min. 25℃ / min, the high temperature and high pressure resistant mold is made of high-strength and high-purity graphite, alumina ceramic or hard alloy material.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. Abandoning the conventional approach of mechanically and physically mixing graphene and copper powder in traditional processes, we innovatively propose a preparation strategy of first constructing a three-dimensional porous pure copper framework and then performing in-situ chemical vapor deposition. By using the porous copper framework as a three-dimensional growth template, graphene can achieve in-situ and uniform growth in its complex internal pore network, reducing the aggregation of graphene and achieving highly uniform dispersion of graphene in the copper matrix. 2. This invention combines the advantages of high-quality growth by chemical vapor deposition with the large-scale preparation by powder metallurgy. It uses a pre-fabricated porous pure copper skeleton as a three-dimensional template for in-situ secondary vapor phase reaction sintering growth, which solves the technical bottleneck of graphene's easy agglomeration and difficulty in dispersion in metal matrix. 3. This method effectively avoids the tearing and damage to the graphene structure caused by traditional mechanical mixing, and successfully constructs a complete and continuous three-dimensional graphene thermal / electrical network in the copper matrix, releasing the performance potential of graphene. At the same time, this method has the advantages of easy control of process variables, high batch stability, and low production cost for large-scale preparation. Attached Figure Description

[0015] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention.

[0016] Figure 1 A flowchart illustrating a method for mass production of graphene copper provided in an embodiment of the present invention. Detailed Implementation

[0017] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” or “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, apparatus, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0018] For ease of understanding, the specific process of the embodiments of the present invention is described below. Please refer to [link / reference]. Figure 1 The flowchart of the method for mass production of graphene copper provided in this embodiment of the invention includes the following steps: S1. Select micron-sized copper powder and place it in a high-temperature heating furnace at 200°C under air or pure oxygen atmosphere. Heat treatment at 500℃ for 0.5 seconds After 3 hours, pre-oxidized copper powder with a copper oxide / cuprous oxide shell on the surface is obtained; S2. Mix the pre-oxidized copper powder with the pore-forming agent and volatile binder, press it into a blank, and heat it at 700℃. Insulated at 900℃ in a high-purity hydrogen atmosphere for 2 hours A three-dimensional interconnected porous pure copper skeleton was obtained in 4 hours; S3. The three-dimensional interconnected porous pure copper framework is heated to 850℃. Pretreatment at 1050℃ under hydrogen gas followed by initial vapor deposition using carbon source gas. S4. Stop the carbon source and anneal in situ at a constant temperature in a pure hydrogen environment. Then introduce the carbon source again for a second slow vapor deposition for 30-60 minutes to obtain a graphene-coated porous copper framework. S5. The graphene-coated porous copper skeleton is hot-pressed and densified, then cooled under pressure to below 200°C and demolded to obtain the graphene-copper composite material.

[0019] In this embodiment, step S1 involves selecting a certain amount of micron-sized copper powder with a particle size of 5–500 μm and placing it in a high-temperature heating furnace. Under an air or pure oxygen atmosphere, the powder is heat-treated at 200℃–500℃ for 0.5–3 hours. This step aims to control the oxidation temperature and time to allow a uniform copper oxide / cuprous oxide shell layer to grow in situ on the surface of the copper powder, thereby obtaining pre-oxidized copper powder with a core-shell structure, which provides a basis for subsequent high-activity sintering. The thickness of the copper oxide / cuprous oxide shell layer is 50–500 nm.

[0020] In this embodiment, in step S2, the pre-oxidized copper powder is mixed with granular pore-forming agent and volatile binder in a uniform ratio and then pressed into a porous precursor green body with a certain initial strength; then it is placed in a tube furnace and kept at a high-purity hydrogen atmosphere of 700℃-900℃ for 2-4 hours. During this high-temperature reduction process, the oxide layer on the surface of the copper powder is reduced in situ to nascent nano-copper active atoms with extremely high surface energy. These highly active atoms rapidly diffuse at the particle contact sites, forming robust metallurgical bonding necks with a low energy barrier. After furnace cooling, a pure copper framework with high porosity, good structural strength, and three-dimensional interconnected internal pores is obtained. Based on the mass of the pre-oxidized copper powder, the pore-forming agent is added at a ratio of 10 wt%, and the volatile binder is added at a ratio of 2 wt%. The pore-forming agent is one or more of ammonium bicarbonate, urea, and sodium chloride, and the volatile binder is one or more of polyvinyl alcohol, polyethylene glycol, polymethyl methacrylate, and paraffin wax. The porosity of the prepared three-dimensional porous pure copper framework is 35%. 65% of the average pore size is 10 μm Between 200μm, the internal pores exhibit a three-dimensional interconnected structure.

[0021] In this embodiment, step S3 involves placing the prepared three-dimensional porous pure copper framework in the high-temperature constant-temperature zone of a gas-phase reaction sintering furnace. After evacuating and removing the air, the framework is pretreated for 20-60 minutes under hydrogen protection at 850℃-1050℃ to thoroughly remove adsorbed impurities on the framework surface and expose more highly active catalytic sites using thermal etching. Subsequently, a carbon source gas is introduced. During the first gas-phase deposition, the flow ratio of carbon source gas to hydrogen is 1:5 to 1:10. The carbon source gas is one or more mixed gases selected from methane, ethylene, and acetylene. The first deposition is carried out for 5-15 minutes under a deposition pressure of 50-500 Pa. In this stage, a high carbon source concentration is used to promote the rapid "dissolution-precipitation" or catalytic growth of carbon atoms on the complex porous copper surface, achieving large-area rapid nucleation and initial coverage of graphene.

[0022] In this embodiment, step S4 involves shutting off the carbon source gas and maintaining a high-temperature in-situ isothermal annealing process in a pure hydrogen environment for 10-20 minutes. Utilizing the weak etching effect of high-temperature hydrogen on the carbon material, amorphous carbon and unstable graphene edges generated during the primary deposition are preferentially removed, exposing grain boundary defects in the primary graphene network. Subsequently, the carbon source gas is reintroduced, and the flow ratio of carbon source to hydrogen is significantly reduced to 1:15 to 1:25 for a second slow deposition process of 30-60 minutes. Under low carbon source concentration, the grown carbon atoms tend to fill and stitch at the exposed defect sites. After deposition, the furnace is cooled, ultimately obtaining a graphene / porous copper framework with a high-quality, continuous, seamless three-dimensional graphene network fully encapsulated.

[0023] In this embodiment, step S5 involves loading a porous copper framework loaded with graphene into a high-strength mold and heating it to 750℃-1000℃ under vacuum or inert protective gas, with the heating rate controlled at 3℃ / min. 25℃ / min. After reaching the set temperature, apply a uniaxial directional pressure of 10-80MPa and hold for 1-3 hours. Under the thermo-mechanical coupling effect of high temperature and high pressure, the pure copper skeleton undergoes plastic deformation, the pores are completely squeezed and closed, and the adjacent copper matrix undergoes deep metallurgical bonding, embedding the graphene network seamlessly into the dense copper grain boundaries. Finally, the pressure must be maintained while cooling in the furnace to below 200℃ before depressurization and demolding to prevent thermal stress rebound and interface microcracks caused by sudden depressurization at high temperature. This yields a fully dense, highly conductive and thermally conductive graphene / copper-based composite material. The high-temperature and high-pressure resistant mold is made of high-strength, high-purity graphite, alumina ceramic, or hard alloy.

[0024] The present invention has low reaction requirements, is simple to operate, and can achieve mass production. Several practical examples are listed below to illustrate the technical solution of the present invention.

[0025] Case 1. High-purity spherical micron-sized copper powder with a particle size of 50 μm was selected and placed in a high-temperature heating furnace. Under an air atmosphere, it was heat-treated at 300°C for 2 hours to allow a uniform oxide layer to grow in situ on the surface of the copper powder, obtaining pre-oxidized copper powder. This pre-oxidized copper powder was then mixed with ammonium bicarbonate and polyvinyl alcohol in a specific ratio and pressed into a porous precursor. Subsequently, it was placed in a tube furnace and held at 800°C in a pure hydrogen atmosphere for 3 hours to allow for in-situ reduction and sintering. Finally, this porous pure copper framework was placed in a gas-phase reaction sintering furnace, and the air was vented. After gasification, the graphene was pretreated for 30 minutes under hydrogen protection at 1000℃. Then, methane was introduced, with a methane to hydrogen flow ratio of 1:8, and initial deposition was performed for 10 minutes at 200Pa pressure to achieve rapid nucleation and preliminary growth of graphene. The methane gas was then shut off, and the graphene / hydrogen was annealed in situ at a constant temperature for 15 minutes in a pure hydrogen environment. Methane was then reintroduced, and the methane to hydrogen flow ratio was reduced to 1:20 for a second deposition of 45 minutes. After deposition, the graphene / porous copper framework was cooled in the furnace to obtain a fully graphene-coated graphene / porous copper framework. This graphene / porous copper framework was placed in a high-strength mold and heated to 800℃ under vacuum. After reaching the set temperature, a uniaxial pressure of 50MPa was applied and held at that temperature and pressure for 2 hours to achieve densification. Finally, while maintaining a pressure of 50MPa, the framework was cooled in the furnace to below 150℃, and the pressure was released and the mold was demolded to obtain a fully densified graphene / copper-based composite material.

[0026] Case 2. Dendritic irregular micron-sized copper powder with a particle size of 100 μm was selected and placed in a high-temperature furnace. Under a pure oxygen atmosphere, it was heat-treated at 400°C for 1 hour to allow a uniform oxide layer to grow in situ on the surface of the copper powder, obtaining pre-oxidized copper powder. This pre-oxidized copper powder was then mixed with urea and polyethylene glycol in a specific ratio and pressed into a porous precursor. Subsequently, it was placed in a tube furnace and held at 900°C in a pure hydrogen atmosphere for 2 hours to allow for in-situ reduction and sintering, resulting in a three-dimensionally interconnected porous pure copper framework. This porous pure copper framework was then placed in a gas-phase reaction sintering furnace, and after evacuation and air removal, pre-treated at 950°C under hydrogen protection for 40 minutes. Ethylene was then introduced, with an ethylene to hydrogen flow ratio of 1:6, and the process was carried out at a pressure of 300 Pa. The initial deposition lasted 8 minutes, achieving rapid nucleation and preliminary growth of graphene. The ethylene gas was then shut off, and the graphene was annealed in situ at a constant temperature for 12 minutes in a pure hydrogen environment. Subsequently, ethylene was reintroduced, and the ethylene to hydrogen flow ratio was reduced to 1:18 for a second deposition lasting 50 minutes. After deposition, the graphene / porous copper framework was cooled in the furnace to obtain a fully graphene-coated graphene structure. This graphene / porous copper framework was then placed in a high-strength alumina ceramic mold and heated to 900°C under argon protection. Once the set temperature was reached, a uniaxial pressure of 60 MPa was applied and held at that temperature and pressure for 1.5 hours to achieve full densification. Finally, while maintaining a pressure of 60 MPa, the furnace was cooled to below 180°C, and the pressure was released and the mold was demolded, ultimately yielding a fully densified graphene / copper-based composite material.

[0027] Case 3. High-purity spherical copper powder with a particle size of 20 μm was selected and placed in a high-temperature heating furnace. Under an air atmosphere, it was heat-treated at 250°C for 2.5 hours to allow a uniform oxide layer to grow in situ on the surface of the copper powder, obtaining pre-oxidized copper powder. This pre-oxidized copper powder was then mixed with sodium chloride and paraffin in a specific ratio and pressed into a porous precursor. Subsequently, it was placed in a tube furnace and held at 750°C in a pure hydrogen atmosphere for 4 hours to allow for in-situ reduction and sintering, resulting in a three-dimensionally interconnected porous pure copper framework. This porous pure copper framework was placed in a gas-phase reaction sintering furnace, and after evacuation and air removal, it was pre-treated at 900°C under hydrogen protection for 50 minutes. Then, acetylene was introduced, with an acetylene to hydrogen flow ratio of 1:10, at a pressure of 100 Pa. The initial deposition process lasted 12 minutes to achieve rapid nucleation and preliminary growth of graphene. Acetylene gas was then shut off, and the graphene was annealed in situ at a constant temperature in a pure hydrogen environment for 18 minutes. Acetylene was then reintroduced, and the acetylene-to-hydrogen flow ratio was reduced to 1:22 for a second deposition process lasting 35 minutes. After deposition, the graphene / porous copper framework was cooled in the furnace to obtain a fully graphene-coated graphene / porous copper framework. This graphene / porous copper framework was then placed in a high-strength graphite mold and heated to 850°C in a vacuum environment. Once the set temperature was reached, a uniaxial pressure of 30 MPa was applied, and the mold was maintained at this temperature and pressure for 2.5 hours to achieve full densification. Finally, while maintaining a pressure of 30 MPa, the furnace was cooled to below 190°C, and the pressure was released and the mold was demolded, resulting in a fully densified graphene / copper-based composite material.

[0028] Case 4. High-purity spherical copper powder with a particle size of 200 μm was selected and placed in a high-temperature heating furnace. Under an air atmosphere, it was heat-treated at 350°C for 1.5 hours to allow a uniform oxide layer to grow in situ on the surface of the copper powder, obtaining pre-oxidized copper powder. This pre-oxidized copper powder was then mixed with ammonium bicarbonate and polymethyl methacrylate in a specific ratio and pressed into a porous precursor. Subsequently, it was placed in a tube furnace and held at 850°C in a pure hydrogen atmosphere for 2.5 hours to allow for in-situ reduction and sintering, resulting in a three-dimensionally interconnected porous pure copper framework. This porous pure copper framework was placed in a gas-phase reaction sintering furnace, and after evacuation and air removal, it was pre-treated at 1050°C under hydrogen protection for 25 minutes. Then, a mixed carbon source of methane and ethylene was introduced, with a flow rate ratio of 1:7 between the mixed carbon source and hydrogen, at 250 Pa. The initial deposition was performed under atmospheric pressure for 9 minutes to achieve rapid nucleation and preliminary growth of graphene. The mixed carbon source gas was then shut off, and the graphene was annealed in situ at a constant temperature in a pure hydrogen environment for 16 minutes. Subsequently, a mixed carbon source of methane and ethylene was reintroduced, and the flow ratio of the mixed carbon source to hydrogen was reduced to 1:20 for a second deposition of 40 minutes. After deposition, the graphene / porous copper skeleton was cooled in the furnace to obtain a graphene-encapsulated graphene / porous copper skeleton. The graphene / porous copper skeleton was then placed in a high-strength cemented carbide mold and heated to 880°C under argon protection. After reaching the set temperature, a uniaxial pressure of 40 MPa was applied and held at that temperature and pressure for 2 hours to achieve full densification. Finally, while maintaining a pressure of 40 MPa, the graphene / copper-based composite material was cooled in the furnace to below 160°C, depressurized, and demolded to obtain the final fully densified graphene / copper-based composite material.

[0029] Case 5. High-purity ultrafine spherical copper powder with a particle size of 5 μm was selected and placed in a high-temperature heating furnace. Under a pure oxygen atmosphere, it was heat-treated at 220°C for 3 hours to allow a uniform oxide layer to grow in situ on the copper powder surface, obtaining pre-oxidized copper powder. This pre-oxidized copper powder was mixed with urea and polyvinyl alcohol in a specific ratio and pressed into a porous precursor. Subsequently, it was placed in a tube furnace and held at 700°C in a pure hydrogen atmosphere for 3.5 hours to allow for in-situ reduction and sintering, resulting in a three-dimensionally interconnected porous pure copper framework. This porous pure copper framework was placed in a gas-phase reaction sintering furnace, and after evacuation, pretreated at 850°C under hydrogen protection for 60 minutes. Then, methane was introduced, with a methane to hydrogen flow ratio of 1:5, and initial deposition was performed at 50 Pa pressure for 15 minutes, achieving rapid nucleation and preliminary growth of graphene. The methane gas was shut off, and the mixture was in-situ annealed at a constant temperature in a pure hydrogen environment for 20 minutes. Then, methane was reintroduced, and the methane to hydrogen flow ratio was reduced to 1:15 for a second deposition process of 60 minutes. After deposition, the mixture was cooled in the furnace to obtain a graphene / porous copper framework fully coated with graphene. This graphene / porous copper framework was then placed in a high-strength graphite mold and heated to 750°C under vacuum. Once the set temperature was reached, a uniaxial pressure of 80 MPa was applied and held at that temperature and pressure for 1 hour to achieve full densification. Finally, while maintaining the 80 MPa pressure, the mixture was cooled in the furnace to below 120°C, the pressure was released, and the mold was demolded, yielding the fully densified graphene / copper-based composite material.

[0030] For the five groups of graphene / copper-based composite material samples (Case 1, Case 2, Case 3, Case 4, and Case 5) prepared according to the method of this invention, the Archimedes displacement method was used to test the density, the eddy current conductivity meter was used to test the conductivity, the laser scintillation method was used to test the thermal conductivity, and the scanning electron microscope was used to observe the microstructure and graphene dispersion state. The comprehensive performance of the materials was comprehensively tested and systematically analyzed. The experimental results and performance analysis are as follows: The graphene / copper-based composite material prepared in Case 1 achieved a density of 99.3%, with internal pores completely closed under hot-pressing and cooling processes, leaving no residual voids or interface defects, resulting in a uniform and dense overall structure. Its electrical conductivity reached 106.2% IACS, significantly higher than conventional pure copper materials, indicating that the three-dimensional continuous graphene network effectively constructed efficient conductive pathways within the copper matrix, greatly improving the material's conductivity. Its thermal conductivity reached 458 W / (m·K), demonstrating significant advantages in electronic heat dissipation and high-power device thermal conductivity applications, enabling rapid heat conduction and diffusion. Scanning electron microscopy revealed that graphene completely encapsulated the porous copper framework surface. The graphene exhibits no agglomeration, stacking, or structural damage, and is uniformly distributed between copper grain boundaries. The interface is tightly bonded without gaps, cracks, or delamination, demonstrating that secondary chemical vapor deposition and intermediate annealing can effectively repair graphene defects and form a high-quality continuous graphene network. This embodiment utilizes medium-sized spherical copper powder, a single methane carbon source, and a medium-temperature, medium-pressure hot-pressing process. The preparation process is stable and controllable, with high batch-to-batch consistency. The resulting composite material exhibits balanced comprehensive performance, combining excellent electrical conductivity, thermal conductivity, and structural strength. It can meet the usage requirements of most high-end application scenarios such as 5G communication devices, general electronic heat dissipation components, and high-power conductive connectors, possessing significant industrialization potential.

[0031] The graphene / copper-based composite material prepared in Case 2 had a density of 98.9%, slightly lower than that of Example 1. This was mainly due to the slightly larger number of voids formed by the dendritic irregular copper powder particles compared to spherical copper powder, but it remained at a fully dense level, fully meeting the requirements for integrated structural and functional devices. Its electrical conductivity was 103.5% IACS, maintaining excellent conductivity. Although slightly lower than that of Example 1, it was still significantly better than the graphene-copper composite material prepared by the traditional copper-based material and mechanical mixing method. Its thermal conductivity was 435 W / (m·K), demonstrating efficient heat dissipation capabilities, making it suitable for applications with high thermal conductivity requirements. Microscopic morphology observations showed that the graphene along the dendritic... The three-dimensional skeleton constructed from dendritic copper powder grows uniformly on both the inner and outer surfaces, resulting in a robust skeleton structure, sufficient metallurgical bonding, and outstanding mechanical properties. Its tensile strength and hardness are both higher than those of conventional pure copper materials. In this embodiment, dendritic copper powder, ethylene carbon source, and high-temperature and high-pressure processes are used to prepare composite skeletons with higher strength and stronger structural stability. They are not easily deformed or cracked under stress conditions, making them suitable for scenarios with high requirements for mechanical properties and structural reliability. At the same time, the ethylene carbon source has strong deposition stability, the pore-forming agent and binder are reasonably matched, the porous skeleton has good molding effect, the graphene grows uniformly, and the overall process has strong adaptability. It can be used to prepare integrated parts that combine structural support and electrical and thermal conductivity.

[0032] The graphene / copper-based composite material prepared in Case 3 achieved a density of 99.5%, which is among the highest in the five examples. The fine-particle copper powder was densely packed, and the pores were completely closed after hot pressing, with no porosity defects. Its electrical conductivity reached 108.7% IACS, demonstrating excellent conductivity, which is outstanding in conventional single-carbon source systems and can meet the conductivity requirements of high-precision, low-loss electronic components. Its thermal conductivity reached 472 W / (m·K), providing high heat dissipation efficiency and enabling rapid reduction of device operating temperature, thus improving product lifespan and stability. Scanning electron microscopy characterization results showed that the 20μm fine copper powder has a large specific surface area, more complete oxidation-reduction, and more surface active sites. Graphene exhibits more uniform nucleation on its surface, and the highly active acetylene carbon source can achieve high-quality growth under low temperature and low pressure. The amorphous carbon content is extremely low, resulting in fewer graphene defects and higher crystallinity. It presents a continuous and uniform distribution in the copper matrix, without agglomeration, breakage, or interface separation. This embodiment uses fine-particle-size spherical copper powder, acetylene carbon source, and low-temperature and low-pressure processes. While ensuring ultra-high density and excellent electrical and thermal conductivity, it reduces the energy consumption of vapor deposition and hot pressing processes. The prepared composite material has high dimensional accuracy and uniform microstructure, making it suitable for high-end applications with stringent performance and dimensional accuracy requirements, such as high-precision electronic devices, high-frequency communication modules, ultra-thin heat sinks, and precision conductive connectors. It has great application potential.

[0033] The graphene / copper-based composite material prepared in Case 4 had a density of 98.6%. Due to the use of copper powder with a larger particle size of 200 μm, the interparticle porosity was slightly larger, resulting in a slightly lower density than the fine-particle-size examples, but it still met the standards for industrial mass production. Its electrical conductivity was 102.1% IACS, maintaining a stable high-performance conductivity level, far exceeding that of ordinary copper alloy materials. Its thermal conductivity was 426 W / (m·K), demonstrating good heat dissipation capabilities and meeting the performance requirements of most industrial conductive and heat-conducting components. Microstructural observation showed that the three-dimensional porous pure copper framework had large pore sizes, with graphene completely encapsulating the inner walls of the large-pore framework, forming a continuous and interconnected three-dimensional structure. The conductive and thermally conductive network exhibits no localized agglomeration or detachment, resulting in a strong interface bond. This embodiment employs coarse-grained copper powder, a mixed carbon source of methane and ethylene, and a medium-to-high-pressure hot-pressing process. The coarse copper powder raw material is lower in cost and widely available. The mixed carbon source combines the advantages of rapid graphene nucleation with high-quality, slow growth, improving deposition efficiency while ensuring the integrity of the graphene structure. The process has high fault tolerance and strong scalability, making it suitable for large-size, high-volume, and low-cost industrial production. It can be widely applied in cost-sensitive and high-demand scenarios such as electrodes for new energy power batteries, high-power electrical conductive components, and industrial heat dissipation modules. This is the preferred process solution for achieving large-scale mass production of this invention.

[0034] The graphene / copper-based composite material prepared in Case 5 achieved a density of 99.6%, the highest among the five examples. The 5μm ultrafine copper powder exhibited extremely high activity, forming numerous highly active sintering sites after oxidation-reduction, resulting in optimal hot-pressing densification and the absence of any internal pores or defects. Its electrical conductivity reached 109.3% IACS, and its thermal conductivity reached 480 W / (m·K), demonstrating superior overall electrical and thermal conductivity, surpassing existing conventional graphene-copper composite materials and approaching the theoretical performance limit. Microscopic morphology analysis revealed that the porous framework constructed by the ultrafine copper powder had small pore sizes and a large specific surface area, allowing graphene to form an ultrathin, uniform coating layer on its surface, free from agglomeration, wrinkles, and structural damage, facilitating secondary deposition. After annealing, the graphene grain boundary defects are completely repaired, forming a near-perfect continuous three-dimensional graphene network that forms a strong interfacial bond with the copper matrix, without stress concentration or microcracks. This embodiment uses ultrafine copper powder, methane carbon source, and low-temperature high-pressure process to retain the intrinsic properties of graphene to the greatest extent and fully release the advantages of graphene in terms of conductivity, thermal conductivity, reinforcement, and toughening. The prepared composite material has ultra-high density, ultra-high electrical and thermal conductivity, and excellent mechanical properties, which can meet the stringent requirements of extreme working conditions and high-end fields such as high-end chip heat dissipation, high-power new energy devices, ultra-high frequency communication equipment, and aerospace precision conductive components, representing the optimal performance level that the technical solution of this invention can achieve.

[0035] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for mass production of graphene copper, characterized in that, The method includes the following steps: S1. Select micron-sized copper powder and place it in a high-temperature heating furnace at 200°C under air or pure oxygen atmosphere. Heat treatment at 500℃ for 0.5 seconds After 3 hours, pre-oxidized copper powder with a copper oxide / cuprous oxide shell on the surface is obtained; S2. Mix the pre-oxidized copper powder with the pore-forming agent and volatile binder, press it into a blank, and heat it at 700℃. Insulated at 900℃ in a high-purity hydrogen atmosphere for 2 hours A three-dimensional interconnected porous pure copper skeleton was obtained in 4 hours; S3. The three-dimensional interconnected porous pure copper framework is heated to 850℃. Pretreatment at 1050℃ under hydrogen gas followed by initial vapor deposition using carbon source gas. S4. Stop the carbon source and anneal in situ at a constant temperature in a pure hydrogen environment. Then introduce the carbon source again for a second slow vapor deposition for 30-60 minutes to obtain a graphene-coated porous copper framework. S5. The graphene-coated porous copper skeleton is hot-pressed and densified, then cooled under pressure to below 200°C and demolded to obtain the graphene-copper composite material.

2. The method for mass production of graphene copper as described in claim 1, characterized in that, In step S1, the copper powder particle size is 5–500 μm, and the copper oxide / cuprous oxide shell thickness is 50–500 nm.

3. The method for mass production of graphene copper as described in claim 1, characterized in that, The specific process of step S2 includes: The pre-oxidized copper powder is mixed with the pore-forming agent and volatile binder in a uniform ratio and then pressed into a porous precursor green body. The porous precursor green body is placed in a tube furnace and kept at a high-purity hydrogen atmosphere of 700℃-900℃ for 2-4 hours. During the high-temperature reduction process, the oxide layer on the surface of the copper powder is reduced in situ to nascent nano-copper active atoms. The active atoms of nascent nano-copper diffuse at the particle contact sites, forming a metallurgical bonding neck. After cooling in the furnace, a three-dimensional interconnected porous pure copper framework is obtained.

4. The method for mass production of graphene copper as described in claim 1, characterized in that, In step S2, based on the mass of the pre-oxidized copper powder, the addition ratio of the pore-forming agent is 10 wt%, and the addition ratio of the volatile binder is 2 wt%. The pore-forming agent is one or more of ammonium bicarbonate, urea, and sodium chloride, and the volatile binder is one or more of polyvinyl alcohol, polyethylene glycol, polymethyl methacrylate, and paraffin wax.

5. The method for mass production of graphene copper as described in claim 1, characterized in that, The three-dimensional porous pure copper framework prepared in step S2 has a porosity of 35%. 65% of the average pore size is 10 μm Between 200μm, the internal pores exhibit a three-dimensional interconnected structure.

6. The method for mass production of graphene copper as described in claim 1, characterized in that, The specific process of step S3 includes: The three-dimensional interconnected porous pure copper framework is placed in the high temperature constant temperature zone of the gas phase reaction sintering furnace. After evacuating the air, it is pretreated for 20-60 minutes under hydrogen protection at 850℃-1050℃ to remove adsorbed impurities on the surface of the three-dimensional interconnected porous pure copper framework and expose more highly active catalytic sites by thermal etching. Carbon source gas is introduced, and the first vapor deposition is carried out for 5-15 minutes under a deposition pressure of 50-500 Pa, so that carbon atoms nucleate and initially cover the surface of the three-dimensional interconnected porous pure copper framework.

7. The method for mass production of graphene copper as described in claim 1, characterized in that, In step S3, the flow ratio of carbon source gas to hydrogen during the first vapor phase deposition is 1:5 to 1:

10. In step S4, the flow ratio of carbon source gas to hydrogen during the second slow vapor phase deposition is 1:15 to 1:

25. The first vapor phase deposition and the second slow vapor phase deposition are connected by in-situ annealing with intermediate pure hydrogen.

8. The method for mass production of graphene copper as described in claim 7, characterized in that, The carbon source gas is one or more of methane, ethylene, and acetylene.

9. The method for mass production of graphene copper as described in claim 1, characterized in that, The specific process of step S5 includes: Graphene-coated porous copper skeletons are placed into high-temperature and high-pressure molds and heated to 750℃-1000℃ under vacuum or inert protective gas. After reaching the set temperature, apply a uniaxial directional pressure of 10-80MPa and maintain the temperature and pressure for 1-3 hours. Under the thermo-coupling effect of high temperature and high pressure, the graphene is embedded in the dense copper grain boundary. Under pressure-maintaining conditions, the material is cooled in the furnace to below 200°C to release pressure and demold, thus obtaining a graphene-copper-based composite material.

10. The method for mass production of graphene copper as described in claim 9, characterized in that, In step S5, the heating rate is controlled at 3℃ / min. 25℃ / min, the high temperature and high pressure resistant mold is made of high-strength and high-purity graphite, alumina ceramic or hard alloy material.

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