Graphene and diamond reinforced copper-based laminar composite material and preparation method thereof

Abstract

The application discloses a graphene and diamond reinforced copper-based laminated composite material and a preparation method thereof. The composite material is composed of surface-modified nickel-plated graphene 0.5-2.5 wt.%, core-shell structure nickel-plated diamond 3-6 wt.% and the balance of copper sheet, with a total of 100 wt.%. The surface-modified graphene is modified graphene using a rutin solution. The surface-modified nickel-plated graphene and the surface nickel-plated diamond are prepared by a chemical plating method. The core-shell structure nickel-plated diamond is realized by ball milling. The application forms a close cross-interlocking bond between the metal matrix and the reinforcing phase, so that the obtained composite material is more compact. The core-shell structure reinforcing phase enhances the comprehensive performance of the composite material by providing its own excellent performance and prolonging the crack path. Finally, the comprehensive performance of the laminated composite material is improved.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, and in particular to a graphene and diamond reinforced copper-based morphological composite material and its preparation method. Background Technology

[0002] Graphene is a novel nanomaterial of carbon, possessing an extremely large specific surface area and high stability, making it considered an ideal catalyst carrier. Graphene / copper composites exhibit high thermal conductivity in the XY plane, but their thermal performance in the perpendicular plane is limited. Diamond / copper composites, due to their high isotropic thermal conductivity, have proven to be the optimal material for effective heat dissipation in integrated and miniaturized devices. Therefore, composites of parallel-oriented graphene, highly thermally conductive diamond particles, and an appropriate proportion of copper can retain all the excellent thermophysical and mechanical properties of these three materials.

[0003] Graphene-diamond reinforced metal matrix composites have superior performance compared to pure metal materials, but they also have at least the following problems: (1) Graphene itself has a large surface free energy; (2) Graphene and diamond and metal matrix have huge differences in structure and performance; (3) Inhomogeneous dispersion of graphene and weak mechanical bonding between graphene and metal matrix; (4) Inhomogeneous dispersion of diamond in metal matrix and weak mechanical bonding with metal matrix. Summary of the Invention

[0004] One of the objectives of this invention is to provide a graphene and diamond-reinforced copper-based composite material to solve the above-mentioned problems.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a graphene and diamond-reinforced copper-based composite material, wherein the composition of the composite material is: 0.5-2.5 wt.% of surface-modified nickel-plated graphene, 3-6 wt.% of core-shell structured nickel-plated diamond, and the balance being copper sheets, totaling 100 wt.%.

[0006] The surface-modified graphene is graphene modified with rutin solution; the surface-modified nickel-plated graphene and the nickel-plated diamond are prepared by chemical plating; the core-shell structured nickel-plated diamond is achieved by ball milling.

[0007] The core-shell structured nickel-plated diamond is located between two layers of copper sheets, forming a layered unit; the surface-modified nickel-plated graphene is located between two layered units, forming an overall layered structure.

[0008] Preferably, the surface-modified nickel-plated graphene and core-shell structured nickel-plated diamond reinforced copper matrix composite material comprises the following components by weight percentage: 0.5-1.5 wt.% surface-modified nickel-plated graphene, 3 wt.% core-shell structured nickel-plated diamond, and the balance being copper sheets.

[0009] Preferably, the surface-modified nickel-plated graphene and core-shell structured nickel-plated diamond reinforced copper-based matrix composite material comprises the following components by weight percentage: 1.5 wt.% surface-modified nickel-plated graphene, 3 wt.% surface-plated diamond, and the balance being copper sheets.

[0010] To address the above issues, it is necessary to improve the dispersion and interfacial bonding of graphene and diamond in the metal matrix. A thin metal film can be deposited on the surface of the reinforcing phase. During the interaction between the reinforcing phase and the matrix, the coating transfers stress concentration areas to these regions, preventing further crack propagation and thus improving the interfacial adhesion of the composite material. Studies have investigated the use of chemical plating to deposit Ni on the surface of copper-based composites. Results show that the presence of Cu / Ni can lead to a tighter bond between the reinforcement and the matrix. This is because the crystal structure of the reinforcing phase differs significantly from that of the matrix, while both Cu and Ni have an FCC structure. After the reinforcing phase surface is coated with a layer of Ni, its structure becomes similar to that of the matrix, resulting in better interfacial wettability and improved interfacial bonding.

[0011] Adding graphene and diamond reinforcements to the matrix can significantly improve the strength of composite materials, but the improvement in toughness is not as obvious, and may even decrease. Core-shell structures can solve this problem well, enhancing both strength and ductility simultaneously, and their overall strengthening and toughening efficiency is superior to previous heterostructures.

[0012] Graphene and diamond possess superior strengthening effects; combining them as a reinforcing phase combines their advantages to enhance the strengthening effect. Furthermore, layered structures can modulate and disrupt shock waves through stress wave scattering, sheet sliding, and sheet interlocking mechanisms. Layered structures are also used in weaponry and blast protection to improve the material's elasticity to impact loads. The core-shell structure's overall strengthening efficiency is superior to previous heterogeneous structures. Therefore, this invention achieves a synergistic effect of multiple strengthening methods, ultimately leading to an improvement in the overall performance of the composite material.

[0013] Compared to traditional non-layered composite materials, the layered composite material of this invention exhibits superior thermal and mechanical properties. On one hand, nickel plating on the surface of the reinforcing phase improves the uniform distribution of the reinforcing phase within the composite material and its interfacial bonding with the copper matrix. On the other hand, the layered structure enhances mechanical properties through the pull-out of the reinforcing phase and the extension of crack initiation paths, while simultaneously creating more thermal and electrical conductive channels, thus improving electrothermal properties. The addition of the core-shell structure hinders dislocation movement and alters crack extension paths, resulting in a combination of high strength and high ductility.

[0014] The second objective of this invention is to provide a method for preparing the above-mentioned surface-modified nickel-plated graphene and core-shell structured nickel-plated diamond-reinforced copper-based composite material, the technical solution of which includes the following steps:

[0015] (1) Graphene was placed in a rutin solution, ultrasonically stirred, allowed to stand, filtered, and vacuum dried to obtain surface-modified graphene.

[0016] (2) The surface-modified graphene or diamond obtained in step (1) is roughened in hydrochloric acid-alcohol solution, sensitized and activated in stannous chloride sensitizer and palladium chloride solution, nickel is plated on the surface by chemical plating, ultrasonic dispersion, standing, filtration and vacuum drying to obtain surface-modified nickel-plated graphene or surface-plated diamond.

[0017] (3) Mix the nickel-plated diamond obtained in step (2) with copper powder and ball mill it to obtain a core-shell structured nickel-plated diamond.

[0018] (4) The copper powder is ball-milled to obtain copper sheets;

[0019] (5) Mix at least one of the surface-modified nickel-plated graphene obtained in step (2) and the core-shell structured nickel-plated diamond obtained in step (3) with the copper sheet obtained in step (4), ball mill, freeze dry, and obtain composite powder.

[0020] (6) The composite powder obtained in step (5) is subjected to vacuum hot pressing sintering, cooling, hot isostatic pressing treatment, and pressure relief cooling to obtain copper-based matrix composite materials with different reinforcing phases.

[0021] As a preferred technical solution, in step (1), the concentration of the rutin aqueous solution is 0.02 ug / mL; the mass ratio of graphene to the volume ratio of rutin aqueous solution is 0.05-0.4 g: 20-80 mL;

[0022] As a preferred technical solution, the ultrasonic dispersion time is 20-40 min; the standing time is 12-36 h; the vacuum drying temperature is 60℃-80℃; and the vacuum drying time is 1-6 h.

[0023] Surface-modified graphene exhibits good dispersibility, low impurity content, and maintains its complete structure.

[0024] The graphene modification method described above employs a novel approach that combines physical and chemical adsorption. This method is highly efficient and reliable, does not generate wastewater or waste acid, and features a simple process that is easy to produce, with stable and reliable modification results.

[0025] As a preferred technical solution, in step (2), the stannous chloride sensitizer is composed of SnCl2 25-35 g / L and HCl 50-70 ml / L; the palladium chloride activator is composed of PdCl2 0.1-0.3 g / L and HCl 5-15 ml / L.

[0026] Sensitization is performed using a weakly acidic stannous chloride sensitizer. The presence of the complexing agent and the relatively low acidity extend the lifespan of the sensitized solution. This also reduces production costs and simplifies wastewater treatment.

[0027] Adding hydrochloric acid to prepare an ionic palladium activation solution can effectively reduce plating defects, improve coating quality, extend the service life of the activation solution, and enhance the activation effect.

[0028] The main salt components in electroless plating are NiSO4·6H2O 25g / L, NaH2PO4·H2O 24g / L, and Na3C6H5O7·2H2O 10g / L. The pH is adjusted to 10–11 using an ammonia solution at 45℃. Only when the electroless plating solution itself remains relatively stable and undergoes a slow, spontaneous oxidation-reduction reaction can the plating solution be guaranteed not to fail due to natural decomposition over a long period.

[0029] After surface modification and nickel plating optimization, the physical bonding between the graphene and diamond reinforced phases and the copper substrate is stronger and the interface is better.

[0030] Among the aforementioned methods for nickel plating on graphene and diamond surfaces, the chemical plating method, applicable to a variety of materials, offers significant advantages, particularly for metallizing non-metallic surfaces. Because chemical plating metallizes the substrate surface, the interfacial wettability and bonding strength between graphene / diamond and copper are significantly improved. The process is simple, easy to produce, and yields stable and reliable results.

[0031] As a preferred technical solution, in step (2), the roughening time is 5-15 min, the ultrasonic dispersion time is 20-40 min, the standing time is 12-36 h, the drying temperature is 60-80 °C, and the drying time is 1-6 h.

[0032] As a preferred technical solution, in step (3), stainless steel balls and stainless steel ball tanks are used for ball milling, the ball milling medium is tert-butanol, the ball milling speed is 100-150 rpm, and the ball milling time is 18-22 h.

[0033] As a preferred technical solution, in step (4), stainless steel balls and stainless steel ball tanks are used for ball milling of copper powder, the ball milling medium is tert-butanol, the ball milling speed is 200-450 rpm, and the ball milling time is 4-8 h.

[0034] As a preferred technical solution, in step (5),

[0035] When the surface-modified nickel-plated graphene obtained in step (2) is ball-milled with the copper sheet obtained in step (4), stainless steel balls and stainless steel ball jars are used, the ball milling medium is tert-butanol, the ball milling speed is 200-450 rpm, and the ball milling time is 1-2 h.

[0036] The surface-modified nickel-plated graphene obtained in step (2), the core-shell structured nickel-plated diamond obtained in step (3), and the copper sheet obtained in step (4) are mixed and ball-milled. Alternatively, when ball-milling and mixing the core-shell structured nickel-plated diamond obtained in step (3) and the copper sheet obtained in step (4), stainless steel balls and stainless steel ball jars are used. The ball milling medium is tert-butanol, the ball milling speed is 100-150 rpm, and the ball milling time is 1-2 hours.

[0037] By optimizing and adjusting the ball mill speed and milling time, the ball milling mixing effect can be better achieved, preventing the core-shell structure from being damaged, and further improving the performance of the composite material after sintering.

[0038] The aforementioned method for preparing nickel-plated diamond with a core-shell structure employs ball milling, a simple and easily manufactured process. Through mechanical alloying, hard diamond particles are embedded into the surface of copper spherical powder. The hard diamond particles act as the shell structure, while the soft copper phase is encapsulated inside, serving as the core structure. This core-shell structure achieves a combination of high strength and high ductility.

[0039] As a preferred technical solution, in step (6), the temperature of vacuum hot pressing sintering is 800-1000℃, the pressure of vacuum hot pressing sintering is 20-40MPa, and the holding time of vacuum hot pressing sintering is 1-3h. In step (8), the temperature of hot isostatic pressing is 800-1000℃, the pressure of hot isostatic pressing is 80-120MPa, and the holding time of hot isostatic pressing is 1-3h.

[0040] By performing hot isostatic pressing with the above-mentioned optimal temperature, pressure, and time parameters, a tight cross-linked bond is formed between the metal matrix and the reinforcing phase in the resulting layered composite material, thereby enhancing the effectiveness of the reinforcing phase.

[0041] In the method for preparing the above-mentioned copper-based layered composite material, the graphene is surface-modified to improve its dispersibility; the graphene and diamond are nickel-plated to strengthen the interfacial bond with the copper matrix, thereby improving the interfacial wettability and bonding strength with copper; the diamond is made into a core-shell structure to meet the requirements of high strength and high toughness. To obtain the layered composite material, copper powder is first ball-milled into copper sheets, then mixed and ball-milled with other raw materials to ensure sufficient interaction between the various materials and obtain composite powder. Finally, the composite powder is vacuum hot-pressed and sintered, hot isostatically pressed, and cooled and depressurized to obtain a surface-modified nickel-plated graphene and a core-shell structured nickel-plated diamond-reinforced copper-based layered composite material. The entire preparation method is simple and easy to implement, highly targeted, and has high conversion efficiency for the surface pretreatment of carbon materials. During ball milling, the components are fully mixed, maximizing their reinforcing effect. The reinforcing phase provides its own excellent properties and extends the crack path, ultimately achieving the designed overall properties of the layered composite material, with better mechanical properties and superior thermal and electrical conductivity.

[0042] Compared with the prior art, the advantages of the present invention are as follows:

[0043] (1) In this invention, the surface of graphene is first modified, and then nickel is plated on the surface of graphene and diamond by chemical plating, thereby reducing the agglomeration of the reinforcement in the matrix.

[0044] (2) The layered structure of the surface-modified nickel-plated graphene and the core-shell structure of the nickel-plated diamond reinforced copper matrix composite material prepared by the present invention is obvious and has a highly directional arrangement, providing more heat conduction channels. Therefore, it can build more electrical and thermal conduction channels, thereby enhancing the electrical and thermal conductivity of the composite material. The reinforcement is made into a core-shell structure and embedded in the layered copper matrix to obtain a combination with high strength and high toughness.

[0045] (3) The copper-based layered composite material prepared by the present invention combines the advantages of the reinforcing phase itself with the synergistic effect of multiple strengthening methods, ultimately leading to the improvement of the overall performance of the layered composite material. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the structure of the layered composite material obtained in Example 11 of the present invention;

[0047] Figure 2 These are the thermal performance test results of nickel-plated diamond-reinforced copper-based matrix composite materials with core-shell structures in some embodiments and comparative examples of the present invention;

[0048] Figure 3 These are the thermal performance test results of some embodiments and comparative examples of graphene and diamond-reinforced copper-based matrix composites of the present invention;

[0049] Figure 4 The electrical performance test results are for surface-modified nickel-plated graphene film-reinforced copper-based matrix composites. Detailed Implementation

[0050] The invention will now be further described with reference to the accompanying drawings.

[0051] Example 1

[0052] Preparation of modified graphene

[0053] Graphene was added to a 0.02 μg / mL rutin aqueous solution and ultrasonically dispersed for 30 min, wherein the weight ratio of graphene to the volume of rutin aqueous solution was 0.1 g: 40 mL; after standing for 24 h, it was filtered to remove the filter residue, and then vacuum dried at 60 °C for 2 h to obtain surface-modified graphene.

[0054] Surface-modified graphene has a smooth surface, allowing observation of many individual graphene particles with minimal size variation.

[0055] Example 2

[0056] Preparation of surface-modified nickel-plated graphene

[0057] Surface-modified graphene was roughened by immersing it in a hydrochloric acid-alcohol solution, then sensitized and activated in a stannous chloride and palladium chloride solution. Nickel was then electrolessly plated onto the graphene surface, followed by filtration and vacuum drying to obtain surface-modified nickel-plated graphene. The roughening solution consisted of anhydrous ethanol and 20 ml / L HCl; the sensitization solution consisted of 30 g / L SnCl2 and 60 ml / L HCl; the activation solution consisted of 0.25 g / L PdCl2 and 10 ml / L HCl; the main salt components in the electroless plating were 25 g / L NiSO4·6H2O, 24 g / L NaH2PO4·H2O, and 10 g / L Na3C6H5O7·2H2O. The pH value was adjusted to 10–11 using an ammonia solution at 45°C.

[0058] Surface-modified graphene reinforcements are unevenly distributed in the copper matrix and prone to agglomeration, which affects the bonding between the reinforcement and the metal matrix, thus impacting the composite material's performance. To address the graphene agglomeration problem, nickel plating is applied to its surface using electroless plating. This reduces agglomeration in the copper matrix, improves interfacial bonding, and avoids agglomeration, resulting in a layered composite material with continuous and clean interfacial bonding. The layered structure can further enhance the electrical and thermal conductivity of the composite material by constructing more conductive and thermally conductive networks.

[0059] Example 3

[0060] Preparation of copper sheets

[0061] Copper powder was ball-milled into sheets using stainless steel balls and a stainless steel ball mill. The ball milling medium was tert-butanol, the ball milling speed was 300 rpm, the ball milling time was 6 hours, and the ball-to-material ratio was 1:3.6. After ball milling, the sheets were freeze-dried to obtain copper sheets.

[0062] Example 4

[0063] Preparation of copper-based composite materials

[0064] Take the surface-modified nickel-plated graphene film from Example 2 and the copper sheet from Example 3; by volume, use stainless steel balls and a stainless steel ball mill to mix 10 parts of the surface-modified nickel-plated graphene film and 90 parts of the copper sheet. The milling medium is tert-butanol, the ball-to-material ratio is 1:3.6, the milling speed is 300 rpm, and the milling time is 1.5 h to ensure uniform powder mixing. After milling, freeze-dry to obtain composite powder; the composite powder is then subjected to vacuum hot pressing sintering. The specific process is as follows: the composite powder... The composite material was placed in a graphite mold with a diameter of 55 mm and sintered under the conditions of sintering pressure of 30 MPa, sintering temperature of 900℃, heating rate of 10℃ / min, and holding time of 1.5 h. Then, it was cooled in the furnace and subjected to hot isostatic pressing. The specific process was as follows: the temperature was rapidly increased from room temperature to 650℃ and pressure was applied. When the temperature reached 900℃, the pressure reached 100 MPa and the temperature and pressure were held for 2 h. Finally, the pressure was released and cooled to obtain a surface-modified nickel-plated graphene film-reinforced copper-based composite material.

[0065] Example 5

[0066] Preparation of copper-based composite materials

[0067] Take the surface-modified nickel-plated graphene film from Example 2 and the copper sheet from Example 3; by volume, use stainless steel balls and a stainless steel ball mill to mix 20 parts of the surface-modified nickel-plated graphene film and 80 parts of the copper sheet. The milling medium is tert-butanol, the ball-to-material ratio is 1:3.6, the milling speed is 300 rpm, and the milling time is 1.5 h to ensure uniform powder mixing. After milling, freeze-dry to obtain composite powder; the composite powder is then subjected to vacuum hot pressing sintering. The specific process is as follows: the composite powder... The composite material was placed in a graphite mold with a diameter of 55 mm and sintered under the conditions of sintering pressure of 30 MPa, sintering temperature of 900℃, heating rate of 10℃ / min, and holding time of 1.5 h. Then, it was cooled in the furnace and subjected to hot isostatic pressing. The specific process was as follows: the temperature was rapidly increased from room temperature to 650℃ and pressure was applied. When the temperature reached 900℃, the pressure reached 100 MPa and the temperature and pressure were held for 2 h. Finally, the pressure was released and cooled to obtain a surface-modified nickel-plated graphene film-reinforced copper-based composite material.

[0068] Example 6

[0069] Preparation of copper-based composite materials

[0070] Take the surface-modified nickel-plated graphene film from Example 2 and the copper sheet from Example 3; by volume, use stainless steel balls and a stainless steel ball jar to ball-mill and mix 30 parts of the surface-modified nickel-plated graphene film and 70 parts of the copper sheet. The ball milling medium is tert-butanol, the ball-to-material ratio is 1:3.6, the ball milling speed is 300 rpm, and the ball milling time is 1.5 h to ensure uniform powder mixing. After ball milling, freeze-dry to obtain composite powder; the composite powder is then subjected to vacuum hot pressing sintering. The specific process is as follows: the composite powder... The composite material was placed in a graphite mold with a diameter of 55 mm and sintered under the conditions of sintering pressure of 30 MPa, sintering temperature of 900℃, heating rate of 10℃ / min, and holding time of 1.5 h. Then, it was cooled in the furnace and subjected to hot isostatic pressing. The specific process was as follows: the temperature was rapidly increased from room temperature to 650℃ and pressure was applied. When the temperature reached 900℃, the pressure reached 100 MPa and the temperature and pressure were held for 2 h. Finally, the pressure was released and cooled to obtain a surface-modified nickel-plated graphene film-reinforced copper-based composite material.

[0071] Example 7

[0072] Preparation of core-shell structured nickel-plated diamond

[0073] Diamond was roughened by immersing in a hydrochloric acid-alcohol solution, then sensitized and activated in a solution of stannous chloride and palladium chloride. Nickel was then electrolessly plated onto the diamond surface, followed by filtration and vacuum drying to obtain nickel-plated diamond. The nickel-plated diamond and copper powder were then ball-milled using stainless steel balls and a stainless steel ball jar. The milling medium was tert-butanol, the milling speed was 150 rpm, and the milling time was 20 hours.

[0074] To address the agglomeration problem of diamond, a chemical plating method was used to plate the diamond surface with nickel. The copper sheet was then combined with the nickel-plated diamond, increasing the coupling area and resulting in a tighter interfacial bond. The diamond particles were tightly embedded in the copper matrix, promoting overall densification during sintering and improving mechanical properties and thermal conductivity. By embedding hard diamond particles into the surface of copper spherical powder, the hard diamond particles act as the shell structure, while the soft copper phase is encapsulated inside, acting as the core structure. This core-shell structure achieves a combination of high strength and high ductility.

[0075] Example 8

[0076] Preparation of copper-based composite materials

[0077] Take the nickel-plated diamond with a core-shell structure from Example 7 and the copper sheet from Example 3; by weight, use stainless steel balls and a stainless steel ball mill to mix 3 parts of the nickel-plated diamond with a core-shell structure and 97 parts of the copper sheet. The milling medium is tert-butanol, the ball-to-powder ratio is 1:3.6, the milling speed is 150 rpm, and the milling time is 1.5 h to ensure uniform powder mixing. After milling, freeze-dry to obtain composite powder; the composite powder is then subjected to vacuum hot pressing sintering. The specific process is as follows: place the composite powder into... A graphite mold with a diameter of 55 mm was sintered under the conditions of sintering pressure of 30 MPa, sintering temperature of 900℃, heating rate of 10℃ / min, and holding time of 1.5 h. The composite material was then cooled in the furnace and subjected to hot isostatic pressing. The specific process was as follows: the temperature was rapidly increased from room temperature to 650℃ and pressure was applied. When the temperature reached 900℃, the pressure reached 100 MPa. The temperature and pressure were held for 2 h, and finally the pressure was released and cooled to obtain a core-shell structured nickel-plated diamond-reinforced copper-based composite material.

[0078] Example 9

[0079] Preparation of copper-based composite materials

[0080] Take the nickel-plated diamond with a core-shell structure from Example 7 and the copper sheet from Example 3; by weight, use stainless steel balls and a stainless steel ball mill to mix 4 parts of the nickel-plated diamond with a core-shell structure and 96 parts of the copper sheet. The milling medium is tert-butanol, the ball-to-powder ratio is 1:3.6, the milling speed is 150 rpm, and the milling time is 1.5 h to ensure uniform powder mixing. After milling, freeze-dry to obtain composite powder; the composite powder is then subjected to vacuum hot pressing sintering. The specific process is as follows: place the composite powder into... A graphite mold with a diameter of 55 mm was sintered under the conditions of sintering pressure of 30 MPa, sintering temperature of 900℃, heating rate of 10℃ / min, and holding time of 1.5 h. The composite material was then cooled in the furnace and subjected to hot isostatic pressing. The specific process was as follows: the temperature was rapidly increased from room temperature to 650℃ and pressure was applied. When the temperature reached 900℃, the pressure reached 100 MPa. The temperature and pressure were held for 2 h, and finally the pressure was released and cooled to obtain a core-shell structured nickel-plated diamond-reinforced copper-based composite material.

[0081] Example 10

[0082] Preparation of copper-based composite materials

[0083] Take the nickel-plated diamond with a core-shell structure from Example 7 and the copper sheet from Example 3; by weight, use stainless steel balls and a stainless steel ball mill to mix 5 parts of the nickel-plated diamond with a core-shell structure and 95 parts of the copper sheet. The milling medium is tert-butanol, the ball-to-powder ratio is 1:3.6, the milling speed is 150 rpm, and the milling time is 1.5 h to ensure uniform powder mixing. After milling, freeze-dry to obtain composite powder; the composite powder is then subjected to vacuum hot pressing sintering. The specific process is as follows: the composite powder is placed in... A graphite mold with a diameter of 55 mm was sintered under the conditions of sintering pressure of 30 MPa, sintering temperature of 900℃, heating rate of 10℃ / min, and holding time of 1.5 h. The composite material was then cooled in the furnace and subjected to hot isostatic pressing. The specific process was as follows: the temperature was rapidly increased from room temperature to 650℃ and pressure was applied. When the temperature reached 900℃, the pressure reached 100 MPa. The temperature and pressure were held for 2 h, and finally the pressure was released and cooled to obtain a core-shell structured nickel-plated diamond-reinforced copper-based composite material.

[0084] Example 11

[0085] Preparation of copper-based composite materials

[0086] Take the surface-modified nickel-plated graphene from Example 2, the copper sheet from Example 3, and the core-shell structured nickel-plated diamond from Example 7; by weight, use stainless steel balls and a stainless steel ball jar to ball-mill and mix 3 parts of core-shell structured nickel-plated diamond, 0.5 parts of nickel-plated graphene nanosheets, and 96.5 parts of copper sheet. The ball milling medium is tert-butanol, the ball-to-powder ratio is 1:3.6, the ball milling speed is 150 rpm, and the ball milling time is 1.5 h to ensure uniform powder mixing. After ball milling, freeze-dry to obtain composite powder; the composite powder is then subjected to vacuum hot pressing sintering, specifically as follows: The composite powder was placed into a graphite mold with a diameter of 55 mm and sintered under the conditions of sintering pressure of 30 MPa, sintering temperature of 900℃, heating rate of 10℃ / min, and holding time of 1.5 h. It was then cooled in the furnace, and the composite material was subjected to hot isostatic pressing (HIP). Specifically, the temperature was rapidly increased from room temperature to 650℃, and pressure was applied until the temperature reached 900℃, at which point the pressure reached 100 MPa. This pressure was maintained for 2 h, and finally, the pressure was released and the material was cooled. This yielded a surface-modified nickel-plated graphene nanosheet and a core-shell structured nickel-plated diamond-reinforced copper-based composite material, the structure of which is as follows: Figure 1 As shown, from Figure 1 As can be seen, the nickel-plated diamond with the core-shell structure is located between two layers of copper sheets, forming a layered unit; the surface-modified nickel-plated graphene is located between two layered units, forming a layered structure as a whole.

[0087] Example 12

[0088] Preparation of copper-based composite materials

[0089] Take the surface-modified nickel-plated graphene from Example 2, the copper sheet from Example 3, and the core-shell structured nickel-plated diamond from Example 7; by weight, use stainless steel balls and a stainless steel ball jar to ball-mill and mix 3 parts of core-shell structured nickel-plated diamond, 1 part of nickel-plated graphene nanosheets, and 96 parts of copper sheet. The ball milling medium is tert-butanol, the ball-to-powder ratio is 1:3.6, the ball milling speed is 150 rpm, and the ball milling time is 1.5 h to ensure uniform powder mixing. After ball milling, freeze-dry to obtain composite powder; the composite powder is then subjected to vacuum hot pressing sintering, specifically as follows: The composite powder was placed into a graphite mold with a diameter of 55 mm and sintered under the conditions of sintering pressure of 30 MPa, sintering temperature of 900℃, heating rate of 10℃ / min, and holding time of 1.5 h. Then, it was cooled in the furnace and the composite material was subjected to hot isostatic pressing. The specific process was as follows: the temperature was rapidly increased from room temperature to 650℃ and the pressure was increased to 100 MPa when the temperature reached 900℃. The temperature and pressure were held for 2 h and then the pressure was released and cooled to obtain surface-modified nickel-plated graphene nanosheets and core-shell structured nickel-plated diamond-reinforced copper-based matrix composite materials.

[0090] Example 13

[0091] Preparation of copper-based composite materials

[0092] The surface-modified nickel-plated graphene from Example 2, the copper sheets from Example 3, and the core-shell structured nickel-plated diamond from Example 7 were used. By weight, 3 parts of core-shell structured nickel-plated diamond, 1.5 parts of nickel-plated graphene nanosheets, and 95.5 parts of copper sheets were ball-milled and mixed using stainless steel balls and a stainless steel ball mill. The ball milling medium was tert-butanol, the ball-to-powder ratio was 1:3.6, the ball milling speed was 150 rpm, and the ball milling time was 1.5 h to ensure uniform powder mixing. After ball milling, the powder was freeze-dried to obtain a composite powder. The composite powder was then subjected to vacuum hot pressing sintering. (Specific process details follow.) The composite powder was placed in a graphite mold with a diameter of 55 mm and sintered under the conditions of sintering pressure of 30 MPa, sintering temperature of 900℃, heating rate of 10℃ / min, and holding time of 1.5 h. Then, it was cooled in the furnace and the composite material was subjected to hot isostatic pressing. The specific process was as follows: the temperature was rapidly increased from room temperature to 650℃ and the pressure was increased to 100 MPa when the temperature reached 900℃. The temperature and pressure were held for 2 h and then the pressure was released and cooled to obtain surface-modified nickel-plated graphene nanosheets and core-shell structured nickel-plated diamond-reinforced copper-based composite materials.

[0093] Comparative Example 1

[0094] Copper-based graphene composite material (surface-modified graphene, without nickel plating)

[0095] To verify the effect of the technique of "re-plating nickel on surface-modified graphene", the only difference between this comparative example and Example 4 is that Example 4 uses "surface-modified and then nickel-plated graphene" from Example 2, while this comparative example uses "surface-modified graphene without nickel plating" from Example 1. The rest is the same as Example 4, and a surface-modified graphene film-reinforced copper-based composite material is obtained.

[0096] Comparative Example 2

[0097] Copper-based composite material (copper powder)

[0098] To verify the effect of the technique of "ball milling copper powder into copper sheets", the only difference between this comparative example and Example 8 is that Example 8 uses "copper sheets" that have been ball milled, while this comparative example uses "copper powder" that has not been ball milled. The rest is the same as Example 8, and a core-shell structured nickel-plated diamond-reinforced copper matrix composite material is obtained.

[0099] Comparative Example 3

[0100] Copper-based composite materials (copper powder)

[0101] To verify the effect of the technique of "ball milling copper powder into copper sheets", the only difference between this comparative example and Example 11 is that Example 11 uses "copper sheets" that have been ball milled, while this comparative example uses "copper powder" that has not been ball milled. The rest is the same as Example 11, and surface-modified nickel-plated graphene nanosheets and core-shell structured nickel-plated diamond reinforced copper matrix composite materials are obtained.

[0102] Comparative Example 4

[0103] Copper-based composite material (without hot isostatic pressing)

[0104] To verify the role of the "hot isostatic pressing" technique, this comparative example is the same as Example 13 except that hot isostatic pressing is not performed, and the rest is the same as Example 13. Surface-modified nickel-plated graphene nanosheets and core-shell structured nickel-plated diamond-reinforced copper-based composite materials were obtained.

[0105] Test Example 1

[0106] Thermal performance testing

[0107] This invention employs a laser flare method to test thermal properties. The following relationships exist between thermal conductivity λ, thermal diffusivity α, specific heat capacity C, and material density ρ:

[0108] λ=αρC (1-1)

[0109] Therefore, if the thermal diffusivity α, specific heat capacity C, and material density ρ of a material can be measured, the thermal conductivity of the material can be calculated using equation (1-1). The thermal diffusivity of a material can be directly obtained using the laser scintillation method. Similarly, the thermal diffusivity of a material can be calculated using the Fourier heat transfer equation, as shown in equation (1-2):

[0110]

[0111] Where L is the thickness of the sample, t 1 / 2 This is the half-heating time. The specific heat capacity is obtained through theoretical calculation using literature values, and the thermal conductivity can be obtained by substituting it into (1-1).

[0112] The present invention tested some embodiments and comparative examples according to the above-described test methods, and the results are as follows: Figure 2 and Figure 3 As shown.

[0113] The samples from Comparative Example 2 and Examples 8, 9, and 10 were named A1, A2, A3, and A4, respectively. Figure 2 The thermal conductivity values ​​of all samples are given. It can be seen that: (1) the thermal conductivity gradually increases with the increase of diamond content in the core-shell structure, indicating that the contribution of diamond to thermal conductivity is positive; (2) the thermal conductivity of A2 is higher than that of A1, indicating that the laminated structure plays an important role in improving thermal conductivity. The diamond particle size and surface remain the same to ensure tight coupling with the copper matrix. Therefore, the uniformity of the interface per unit area does not change, and the only change is the diamond content. Therefore, the heat transfer per unit area (thermal coupling) on ​​the interface can be regarded as a constant, and the change in interface thermal conductivity is caused by the coupling region caused by the change between the interfaces. The interfacial heat transfer of diamond-copper composites is attributed to the synergistic effect of phonons and electrons.

[0114] The samples from Comparative Example 3 and Examples 11, 12, and 13 were named B1, B2, B3, and B4, respectively. Figure 3 The thermal conductivity values ​​of the samples are given. It can be seen that: (1) the thermal conductivity and density of the non-layered composite material of Comparative Example 3 are significantly lower than those of the layered composite material; (2) as the mass fraction of nickel-plated graphene nanosheets increases, the thermal conductivity of the composite material gradually increases, and the thermal conductivity reaches its peak when the mass fraction reaches 1.5 wt.%; however, the increase in the thermal conductivity of the composite material is relatively small, which may be because the content of copper-plated graphene nanosheets is not large.

[0115] The theoretical thermal conductivity values ​​for all samples were calculated. Comparison revealed that the experimental and theoretical trends in thermal conductivity were identical. The experimental values ​​were consistently lower than the theoretical values. This can be explained by the lack of chemical affinity and interfacial bonds between copper and diamond, resulting in insufficient electron-phonon coupling for optimal heat transfer. It could also be due to the neglect of interfacial thermal resistance in the theoretical thermal conductivity calculations. Of course, the imperfect density of the samples also plays a role.

[0116] Test Example 2

[0117] Electrical performance testing

[0118] This invention utilizes a simple two-probe method to test conductivity. The two-probe method involves placing the terminals at the top and bottom of the sample for testing. Simultaneously, parameters such as test pressure and holding time are set in the MRMS software. Once the test begins, the software automatically reads data such as electrode thickness, resistance, resistivity, and conductivity. Resistivity and conductivity are reciprocals of each other.

[0119] This invention utilizes the two-probe method to test some embodiments and comparative examples, and the results are as follows: Figure 4 As shown.

[0120] Figure 4 The test results for Comparative Example 1 and Examples 4, 5, and 6 show that the electrical conductivity of the layered composite material gradually increases with the increase of the nickel-plated graphene film content. This is partly because graphene has a higher electrical conductivity than copper, and partly because graphene is almost unconstrained by carbon atoms, and the planar connections increase the channels for free electrons. Furthermore, with the increase of the nickel-copper graphene film content, its specific surface area and contact with the matrix increase, resulting in a stronger strengthening effect. Since the nickel plating improves the bonding effect between the graphene film and the copper sheet, strengthening the "chain reaction" effect, the electrical conductivity of the layered composite material with added nickel-plated graphene film is much greater than that of the layered composite material without nickel-plated graphene film.

[0121] Test Example 3

[0122] Mechanical property testing

[0123] Compression performance testing: This test can measure the elongation at break and compressive strength σ of a material. bc (MPa). The two cross-sections of the compression specimen need to have good parallelism. The compression specimen of this invention is a small cuboid with dimensions of 5×5×8mm. During the compression test, the beam speed is 0.5mm / min. This invention employs a method of multiple experiments to obtain an average value, testing each sample three times, thereby reducing errors and improving the accuracy of the data.

[0124] Tensile property test: The specimen is stretched at a constant speed along its longitudinal principal axis until it fractures or its stress-strain reaches a predetermined value. The load or elongation experienced by the specimen during this process is then measured. This invention primarily tests tensile strength and elongation at break. The dimensions of the tested specimens are 5×5×40 mm. Similar to the compression test, each specimen was tested three times to minimize error.

[0125] The present invention tested some embodiments and comparative examples, and the results are shown in Table 1.

[0126] Table 1 Test Results

[0127] Group <![CDATA[Apparent density (g / cm 3 )]]> Tensile strength (MPa) Compressive strength (MPa) Example 11 96.45％ 178.15 547.35 Example 12 97.03％ 179.63 550.81 Example 13 97.86％ 267.12 663.33 Comparative Example 3 95.73％ 136.34 298.74 Comparative Example 4 93.59％ 220.15 603.57

[0128] Table 1 shows the tensile stress-strain curves and compressive stress-strain curves (at 40% strain) of the composite materials of Comparative Example 3 and Examples 11, 12, and 13, along with their compressive strength. Firstly, the layered composite material exhibits significantly increased tensile and compressive strengths compared to the non-layered composite material. This is because grinding copper powder into flakes increases its specific surface area and the contact area with the reinforcing phase, thereby increasing the density of the composite material and ultimately enhancing its performance. When the graphene content increases to 1.5 wt.%, the tensile and compressive strengths of sample B4 reach their highest levels. This is partly due to the increased content of the reinforcing phase, and since graphene itself has high strength, the layered structure becomes more pronounced with increasing graphene content. Furthermore, the core-shell structure of the nickel-plated diamond alters the crack propagation direction during tension and compression, creating a gradient strain between the core and shell regions and a large accumulation of graphene nanosheets near the core-shell interface. Therefore, a combination of high strength and high ductility is achieved, with the differences in mechanical properties primarily caused by the structure and content of the reinforcing phase.

[0129] Test Example 4

[0130] Density test

[0131] Density is tested using Archimedes' displacement method, and the theoretical density of the sample is calculated based on the content ratio of each component. Density is essentially the ratio of the sample's actual density to its theoretical density.

[0132] This invention uses the Archimedes method to measure the density of the copper-based layered composite materials prepared in Comparative Example 4 and Examples 11, 12, and 13. The results are shown in Table 1 above. It can be found that the copper-based layered composite materials after hot isostatic pressing (HIP) treatment have higher density, tensile strength, and compressive strength. This is because HIP treatment results in uniform strength in all directions of the composite material, eliminates most defects in the composite material, improves the mechanical properties of the composite material, strengthens the bond between the reinforcing phase and the matrix, and makes the composite material more dense. Ultimately, this, along with other reinforcing effects, leads to an increase in the mechanical properties of the layered composite material.

[0133] This invention prepares surface-modified nickel-plated graphene and core-shell structured nickel-plated diamond-reinforced copper-based composite materials by combining sheet powder metallurgy, electroless plating, vacuum hot pressing sintering, and hot isostatic pressing. The following conclusions can be drawn from this process:

[0134] (1) The layered structure of the surface-modified nickel-plated graphene film-reinforced copper-based composite material is obvious, the interface bonding is continuous and free of impurities, and the layered structure has a highly directional arrangement, thus enabling the construction of more conductive and thermally conductive channels, thereby enhancing the electrical and thermal conductivity of the composite material. At the same time, the study found that the layered structure is more obvious and the performance is better when adding nickel-plated graphene film than when adding unplated graphene film.

[0135] (2) A layered structure of nickel-plated diamond-reinforced copper-based composite material with a core-shell structure was successfully constructed. The nickel-plated diamond in the core-shell structure is distributed along the layers, achieving a combination of high strength and high toughness. The construction of the layered structure not only reduces the interface and provides more heat conduction channels, but also hinders dislocation movement. The transfer of load and the strengthening of fine grains play a role in improving the mechanical properties of the composite material.

[0136] (3) Surface-modified nickel-plated graphene nanosheets and core-shell structured nickel-plated diamond-reinforced copper-based layered composite materials combine the advantages of the two reinforcing phases mentioned above. The reinforcing phases enhance the overall performance of the composite material by providing their own superior properties and extending the crack path. By successfully preparing composite materials with both core-shell and layered structures, the synergistic effect of multiple strengthening methods ultimately leads to an improvement in the overall performance of the layered composite material.

[0137] (4) After hot isostatic pressing, the composite material has uniform strength in all directions. This is because the pressure used in hot isostatic pressing can be applied evenly in all directions of the composite material. At the same time, it eliminates most defects in the composite material, improves the mechanical properties of the composite material, makes the bond between the reinforcing phase and the matrix stronger, and makes the composite material denser.

[0138] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A graphene-diamond-reinforced copper-based composite material, characterized in that, The composite material consists of: 0.5-2.5 wt.% surface-modified nickel-plated graphene, 3-6 wt.% core-shell structured nickel-plated diamond, and the balance being copper sheets, totaling 100 wt.%. Among them, graphene was modified with rutin solution to obtain surface-modified graphene, and nickel was plated on the surface of the surface-modified graphene by chemical plating to obtain nickel-plated graphene with surface modification. Nickel-plated diamond is obtained by electroless plating of nickel onto the surface of diamond. The nickel-plated diamond is then mixed with copper powder and ball-milled to obtain the core-shell structured nickel-plated diamond. Copper powder is ball-milled to obtain copper sheets; Surface-modified nickel-plated graphene, core-shell structured nickel-plated diamond, and copper sheets are mixed, ball-milled, and freeze-dried to obtain composite powder; the composite powder is then subjected to vacuum hot pressing sintering, cooling, hot isostatic pressing treatment, and depressurization cooling to obtain a copper-based composite material. The core-shell structured nickel-plated diamond is located between two layers of copper sheets, forming a layered unit; the surface-modified nickel-plated graphene is located between two layered units, forming an overall layered structure.

2. The graphene and diamond-reinforced copper-based composite material according to claim 1, characterized in that, Graphene was placed in a rutin solution, ultrasonically stirred, allowed to stand, filtered, and vacuum dried to obtain surface-modified graphene. The surface-modified graphene was roughened in a hydrochloric acid-alcohol solution, sensitized and activated in a stannous chloride and palladium chloride solution, nickel was electrolessly plated on the surface, ultrasonically dispersed, allowed to stand, filtered, and vacuum dried to obtain surface-modified nickel-plated graphene. The diamond was roughened in a hydrochloric acid-alcohol solution, sensitized and activated in a solution of stannous chloride and palladium chloride, nickel was electrolessly plated on the surface, ultrasonically dispersed, allowed to stand, filtered, and vacuum dried to obtain nickel-plated diamond.

3. The graphene and diamond-reinforced copper-based composite material according to claim 2, characterized in that, The concentration of the rutin solution is 0.02 ug / mL; the mass ratio of graphene to the volume of the rutin solution is 0.05~0.4g:20~80 mL.

4. The graphene and diamond-reinforced copper-based composite material according to claim 2, characterized in that, The ultrasonic dispersion time is 20-40 min; the settling time is 12-36 h; the vacuum drying temperature is 60℃-80℃; and the vacuum drying time is 1-6 h.

5. The graphene and diamond-reinforced copper-based composite material according to claim 2, characterized in that, The stannous chloride sensitizer has the following components: SnCl2: 25~35 g / L, HCl: 50~70 ml / L; the palladium chloride activator has the following components: PdCl2: 0.1~0.3 g / L, HCl: 5~15 ml / L.

6. The graphene and diamond-reinforced copper-based composite material according to claim 2, characterized in that, The roughening time is 5-15 min, the ultrasonic dispersion time is 20-40 min, the standing time is 12-36 h, the drying temperature is 60-80℃, and the drying time is 1-6 h.

7. The graphene and diamond-reinforced copper-based composite material according to claim 1, characterized in that, When ball milling nickel-plated diamond with copper powder, stainless steel balls and stainless steel ball jars are used, tert-butanol is used as the milling medium, the milling speed is 100~150 rpm, and the milling time is 18~22 hours.

8. The graphene and diamond-reinforced copper-based composite material according to claim 1, characterized in that, When ball milling copper powder, stainless steel balls and stainless steel ball jars are used, tert-butanol is used as the milling medium, the ball milling speed is 200~450 rpm, and the ball milling time is 4~8 hours.

9. The graphene and diamond-reinforced copper-based composite material according to claim 1, characterized in that, When ball milling surface-modified nickel-plated graphene, core-shell structured nickel-plated diamond, and copper sheets, stainless steel balls and stainless steel ball jars are used, tert-butanol is used as the milling medium, the milling speed is 100~150 rpm, and the milling time is 1~2 hours.

10. The graphene and diamond-reinforced copper-based composite material according to claim 1, characterized in that, The temperature of vacuum hot pressing sintering is 800~1000℃, the pressure of vacuum hot pressing sintering is 20~40MPa, and the holding time of vacuum hot pressing sintering is 1~3h; the temperature of hot isostatic pressing is 800~1000℃, the pressure of hot isostatic pressing is 80~120MPa, and the holding time of hot isostatic pressing is 1~3h.

Images