Composite metal material based on micro-nano porous copper powder

Abstract

The invention relates to the technical field of metal materials, and discloses a composite metal material based on micro-nano porous copper powder, which is composed of the following components: a matrix is micro-nano porous copper powder with the particle size of 50-500 nanometers, the porosity is 30-80%, and the pore diameter is 20-200 nanometers; the metal additive comprises 5-20 wt% of aluminum powder and 3-15 wt% of nickel powder; the functional additive comprises 1 to 8 weight percent of titanium powder, 0.5 to 5 weight percent of graphene and 0.3 to 3 weight percent of a carbon nano tube; a nickel-titanium alloy coating with the thickness of 50-500 nanometers is formed on the surface of the micro-nano porous copper powder through electrochemical deposition. Through the graded hole design of the micro-nano porous copper powder, a main hole channel provides a rapid electron transmission path, the powder gap stress is eliminated in the low-temperature pre-pressing stage, and atom diffusion and densification are promoted in the high-temperature and high-pressure stage, so that the resistance can be effectively reduced, the loss of energy in the transmission process is reduced, and the energy transmission efficiency of the whole system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of metal materials, in particular to a composite metal material based on micro-nano porous copper powder. Background Art

[0002] Micro-nano porous copper powder composite metal material is a high-performance composite material based on micro-nano porous copper powder, with the addition of various metal, ceramic, polymer and other reinforcing phases, and prepared through advanced technology. In terms of heat dissipation of high-power electronic devices, its excellent thermal conductivity can effectively conduct and dissipate the heat generated by the device during operation, prevent the device from overheating and damage, and improve the stability and life of the device; as an electromagnetic shielding material, it can shield electromagnetic interference and ensure the normal operation of electronic equipment.

[0003] With the development of modern science and technology, the performance requirements for materials in various fields are becoming increasingly stringent. Traditional single copper powder materials or conventional composite materials have some shortcomings in terms of electrical conductivity, mechanical properties, and corrosion resistance. For example, although materials made of pure copper powder have good electrical and thermal conductivity, their strength and hardness are relatively low. When faced with high stress, complex working conditions, and wear environments, they are prone to deformation and damage. Their corrosion resistance also needs to be improved. Some previous composite materials have problems with the bonding between the reinforcement phase and the matrix. The reinforcement phase is prone to agglomeration, resulting in uneven distribution in the matrix and unable to fully exert the reinforcement effect. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present invention provides a composite metal material based on micro-nano porous copper powder, which solves the problems of the traditional materials in terms of electrical conductivity, mechanical properties, etc.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0006] A composite metal material based on micro-nano porous copper powder is composed of the following components: a substrate is micro-nano porous copper powder with a particle size of 50-500 nanometers, a porosity of 30-80%, and a pore diameter of 20-200 nanometers, formed by chemically corroding or electrochemically treating electrolytic copper powder; metal additives include 5-20wt% of aluminum powder and 3-15wt% of nickel powder; functional additives include 1-8wt% of titanium powder, 0.5-5wt% of graphene, and 0.3-3wt% of carbon nanotubes; a nickel-titanium alloy coating with a thickness of 50-500 nanometers is formed on the surface of the micro-nano porous copper powder by electrochemical deposition, and the aluminum powder filling rate inside the pores is ≥85%.

[0007] By adopting the above technical solution: through the hierarchical pore design of micro-nano porous copper powder, the main pores account for 40% to 70% to provide a fast electron transmission path, and the secondary pores account for 20% to 40% to increase the distribution of active sites. Combined with the gradient pressure sintering process, the low-temperature pre-pressing stage eliminates the powder gap stress, and the high-temperature and high-pressure stage promotes atomic diffusion and densification, and ultimately the material's electrical conductivity reaches ≥98% IACS, the tensile strength ≥450MPa, and the pore closure rate ≥90%, which can effectively reduce resistance, reduce energy loss during transmission, and improve the energy transmission efficiency of the entire system.

[0008] Preferably, the micro-nano porous copper powder comprises a hierarchical pore structure, wherein primary pores of 50-200 nanometers account for 40-70% of the total volume, and secondary pores of 10-50 nanometers account for 20-30%;

[0009] The nickel-titanium alloy coating on the surface forms a gradient interface bonding layer with the aluminum powder inside the pores, with a thickness of 10-30 nanometers and an interface bonding strength of ≥150MPa;

[0010] The number of graphene layers is 2-8, the aspect ratio of carbon nanotubes is 500-2000, and the outer diameter is 10-50 nanometers.

[0011] Preferably, in the microstructure:

[0012] Aluminum powder fills the pores to form a continuous conductive network, and the nickel-titanium alloy coating and carbon nanotubes form a pinning effect at the interface;

[0013] Electrical conductivity ≥98% IACS, thermal conductivity ≥350W / m·K, tensile strength ≥450MPa, hardness ≥180HV.

[0014] Preferably, the micro-nano porous copper powder is prepared by any of the following methods:

[0015] Chemical etching method: using 3-8 mol / L HNO3 solution, 50-80℃ etching for 2-6 hours, followed by ultrasonic cleaning with deionized water for 3 times, 5 minutes each time, 40kHz, ultrasonic power density 50-100W / L;

[0016] Electrochemical method: current density 2-5A / dm 2 , pH = 1-3, copper sulfate electrolyte containing 0.1-0.5 mol / L H2SO4, electrolyte temperature 25±2°C, the anode adopts a platinum electrode with a purity of ≥99.9%, and the cathode adopts a copper foil with a thickness of 0.1-0.5 mm and a purity of ≥99.95%.

[0017] Preferably, 1-5 wt% reinforcing phase is added:

[0018] Ceramic particles: Al2O3 or SiC, particle size 0.5-5μm, graded by sieving method, using 800 mesh, 1200 mesh, and 2000 mesh screens for three-level screening, and the hardness is increased by 20-50HV;

[0019] Polymer material: polyimide or polyetheretherketone, with a molecular weight of 10 4 -10 5 , wear resistance increased by 2-5 times;

[0020] The reinforcing phase is evenly distributed by ultrasonic dispersion, and the absolute value of the zeta potential of the slurry after dispersion is ≥30mV, wherein the ultrasonic power is 200-500W, the time is 10-30min, the probe material is titanium alloy, and the diameter is 10-20mm.

[0021] Preferably, performance improvement is achieved through the following collaborative mechanisms:

[0022] The hierarchical porous structure provides high specific surface area and fast ion diffusion channels, with a specific surface area of ≥50m 2 / g, lithium ion diffusion coefficient ≥1×10 -9 cm 2 / s;

[0023] The nickel-titanium alloy coating and carbon nanotubes form a three-dimensional interpenetrating network structure in the matrix, with a thermal conductivity anisotropy ratio of ≤1.2, graphene inhibits grain boundary sliding, and the activation energy of grain boundary migration is ≥200kJ / mol;

[0024] The gradient pressure sintering process controls the grain size to 100-500nm, and the high temperature stability is ≤0.5% creep deformation, wherein the test condition is constant temperature loading at 300℃ for 100 hours.

[0025] Preferably, a preparation method of a micro-nano porous copper powder-based composite metal material is used for the micro-nano porous copper powder-based composite metal material, and the method comprises the following steps:

[0026] S1. Copper powder pretreatment: 100-400 μm electrolytic copper powder was etched in 5-15% nitric acid solution for 10-30 minutes with a stirring rate of 100-300 rpm, and then ultrasonically treated in 3-10% sodium hydroxide solution at a power of 100-300 W and a frequency of 20-40 kHz for 5-15 minutes with an ultrasonic probe diameter of 10-20 mm.

[0027] S2, porous treatment: in 10 -3 -10 -2Under vacuum conditions of Pa, the temperature is raised to 600-800°C at a rate of 5-15°C / min and maintained for 1-3 hours, and an argon-hydrogen mixed gas with a volume ratio of 3:1-5:1 is introduced, wherein the purity of the argon is ≥99.999%, the purity of the hydrogen is ≥99.99%, and the gas flow rate is 10-50 sccm;

[0028] S3. Surface modification: Nickel-titanium alloy layer was deposited by pulsed electrodeposition for 30-120 minutes at a current density of 0.5-3 A / dm 2 , pulse frequency 100-500Hz, duty cycle 30-70%;

[0029] S4. Composite mixing: Mix the modified copper powder with the metal additive and functional phase, add 0.1-0.5% polyvinyl pyrrolidone solution, wherein the molecular weight of the polyvinyl pyrrolidone solution is 40,000-80,000, and the solvent is deionized water, and ball mill for 6-18 hours under argon protection, wherein the ball-to-material ratio is 5:1-10:1, the rotation speed is 200-400 rpm, and the residual oxygen content in the ball mill is ≤10ppm;

[0030] S5, gradient pressure sintering: After cold isostatic pressing to 200-500MPa, -2 -10 -1 Sintering in three stages under Pa vacuum:

[0031] The first stage: heating to 400-500℃ at 2-5℃ / min, keeping warm for 0.5-2 hours, applying axial pressure of 200-300MPa, with a holding pressure accuracy of ±5MPa, controlled by a servo hydraulic system;

[0032] The second stage: heating to 800-950℃ at 5-10℃ / min, keeping warm for 2-6 hours, and simultaneously applying isostatic pressure of 800-1000MPa. The pressure medium is argon with a purity of ≥99.999%. Multi-zone induction heating is used to ensure temperature uniformity of ±3℃.

[0033] The third stage: cool down to below 300℃ at 3-5℃ / min, gradually release the pressure to normal pressure, and maintain the vacuum degree ≤10 during the cooling process. -1 Pa;

[0034] S6. Post-treatment: 5-15% hydrofluoric acid etching for 1-5 minutes, wherein the stirring rate is 50-150 rpm, annealing at 500-700 ° C for 1-3 hours, wherein the annealing atmosphere is a nitrogen-hydrogen mixture with H2 accounting for 5-10%, and finally passivation treatment with 0.1-0.5% benzotriazole ethanol solution at 50-80 ° C for 10-30 minutes. After treatment, nitrogen purging and drying are carried out, wherein the nitrogen dew point is ≤-40 ° C.

[0035] Preferably, the mold preheating temperature used for cold isostatic pressing is 100-200°C, the preheating time is ≥30 minutes, the mold temperature difference before pressing is ≤±5°C, the mold material is cemented carbide, and the surface roughness Ra is ≤0.8μm;

[0036] The sintering furnace used for gradient pressure sintering adopts induction heating, wherein the frequency is 10-50kHz and the temperature fluctuation is controlled within ±2-5°C; the D50 of the powder after ball milling is 5-20μm and the particle size distribution span is (D90-D10) / D50≤1.2.

[0037] Preferably, the relative density of the green body after gradient pressure sintering is ≥95%, and the pore closure rate is ≥90%; the thickness of the surface oxide layer after passivation treatment is ≤10nm, and the salt spray corrosion resistance time is ≥500h.

[0038] Preferably, an application of a micro-nano porous copper powder composite metal material is characterized in that it is applied to high-power heat dissipation devices, lithium-ion battery negative electrodes or electromagnetic shielding materials.

[0039] The present invention provides a composite metal material based on micro-nano porous copper powder.

[0040] Beneficial effects:

[0041] 1. The present invention adopts a hierarchical pore design of micro-nano porous copper powder. The main pores account for 40% to 70% to provide a fast electron transmission path, and the secondary pores account for 20% to 40% to increase the distribution of active sites. Combined with the gradient pressure sintering process, the low-temperature pre-pressing stage eliminates the powder gap stress, and the high-temperature and high-pressure stage promotes atomic diffusion and densification. Ultimately, the material's electrical conductivity reaches ≥98% IACS, the tensile strength ≥450 MPa, and the pore closure rate ≥90%, thereby effectively reducing resistance, reducing energy loss during transmission, and improving the energy transmission efficiency of the entire system.

[0042] 2. The present invention introduces dual-phase reinforcement of ceramic particles and polymer materials. SiC particles with a particle size of 1 to 3 microns improve the wear resistance of the material through their high hardness characteristics, and polyetheretherketone with a molecular weight of 50,000 to 100,000 improves the impact resistance through the flexible phase. The ultrasonic dispersion process is combined with high-energy ball milling to uniformly embed the reinforcement phase into the matrix. The interface bonding strength reaches 15GPa, which can effectively resist the damage to the material caused by external friction. At the same time, when the material is impacted, it absorbs and disperses the impact energy, thereby alleviating the destructive effect of the impact force on the material.

[0043] 3. The present invention forms a gradient nickel-titanium alloy coating by adopting pulsed electrodeposition technology, and controls the uniform growth of grains to 250 nanometers by combining multi-zone induction heating, thereby constructing a three-dimensional thermal conductive network of graphene and carbon nanotubes, so that the part close to the substrate can provide good bonding force, while the surface part has excellent corrosion resistance and wear resistance. The fine and uniform grain structure can increase the number of grain boundaries of the material. The grain boundaries act as obstacles to dislocation movement and can effectively hinder the slip and expansion of dislocations. Through the combination of the thermal conductive network and the nano-grain structure, the thermal stress caused by the difference in thermal expansion coefficient can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a flow chart of a method for preparing a micro-nano porous copper powder composite metal material according to the present invention. DETAILED DESCRIPTION

[0045] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0046] An embodiment of the present invention provides a composite metal material based on micro-nano porous copper powder, which is composed of the following components: a matrix is micro-nano porous copper powder with a particle size of 50-500 nanometers, a porosity of 30-80%, and a pore diameter of 20-200 nanometers, formed by chemical corrosion or electrochemical treatment of electrolytic copper powder; metal additives include 5-20wt% of aluminum powder and 3-15wt% of nickel powder; functional additives include 1-8wt% of titanium powder, 0.5-5wt% of graphene and 0.3-3wt% of carbon nanotubes; a nickel-titanium alloy coating with a thickness of 50-500 nanometers is formed on the surface of the micro-nano porous copper powder by electrochemical deposition, and the aluminum powder filling rate inside the pores is ≥85%.

[0047] Specifically, the higher porosity and moderate particle size and pore size can provide abundant paths for the transmission of electrons, which is beneficial to improving the electrical conductivity of the material. At the same time, the porous structure can increase the bonding area between the material and the additive, providing a good carrier for the preparation of composite materials. Aluminum powder has good electrical conductivity and plasticity. Its addition can improve the overall electrical conductivity of the material, and in the subsequent sintering process, it can form a good metallurgical bond with base metals such as copper powder, thereby enhancing the mechanical properties of the material. Nickel powder not only has excellent electrical conductivity, but also has good corrosion resistance and wear resistance. In the composite material, the addition of nickel powder can improve the Improve the corrosion resistance and wear resistance of materials and extend the service life of materials; titanium powder has high hardness and good biocompatibility, and its addition can improve the hardness and strength of materials; graphene has an extremely high specific surface area and excellent electrical and thermal conductivity. In composite materials, graphene can be used as a conductive filler to further improve the electrical conductivity of materials; at the same time, its good thermal conductivity also helps to improve the heat dissipation performance of materials; carbon nanotubes have excellent mechanical and electrical properties. Their addition can improve the strength and toughness of materials, while also improving the electrical conductivity of materials, and together with graphene, build a three-dimensional thermal and electrical conductive network to improve the overall performance of materials.

[0048] The micro-nano porous copper powder contains a hierarchical pore structure, with primary pores of 50-200 nanometers accounting for 40-70% of the total volume and secondary pores of 10-50 nanometers accounting for 20-30%;

[0049] The nickel-titanium alloy coating on the surface forms a gradient interface bonding layer with the aluminum powder inside the pores, with a thickness of 10-30 nanometers and an interface bonding strength of ≥150MPa;

[0050] The number of graphene layers is 2-8, the aspect ratio of carbon nanotubes is 500-2000, and the outer diameter is 10-50 nanometers.

[0051] Specifically, primary pores of 50-200 nanometers account for 40-70% of the total volume. These primary pores provide fast electron transport pathways, improving the material's electrical conductivity. Secondary pores of 10-50 nanometers account for 20-30% of the total volume. Their presence increases the material's specific surface area, providing more active sites. The nickel-titanium alloy coating improves the material's surface hardness and wear resistance, while also enhancing its corrosion resistance. The gradient interface bonding layer effectively alleviates stress concentration between the substrate and the coating, improving bonding strength and preventing flaking during use, thereby extending the material's service life.

[0052] In the microstructure:

[0053] Aluminum powder fills the pores to form a continuous conductive network, and the nickel-titanium alloy coating and carbon nanotubes form a pinning effect at the interface;

[0054] Electrical conductivity ≥98% IACS, thermal conductivity ≥350W / m·K, tensile strength ≥450MPa, hardness ≥180HV.

[0055] Specifically, the continuous conductive network formed by the aluminum powder filling the pores and the synergistic effect of the nickel-titanium alloy coating and carbon nanotubes jointly strengthen the internal structure of the material, making it more resistant to plastic deformation; among them, components with excellent thermal conductivity such as graphene and carbon nanotubes form efficient heat conduction channels inside the material, allowing heat to be quickly conducted from the inside of the material to the outside.

[0056] Micro-nano porous copper powder is prepared by any of the following methods:

[0057] Chemical etching method: using 3-8 mol / L HNO3 solution, 50-80℃ etching for 2-6 hours, followed by ultrasonic cleaning with deionized water for 3 times, 5 minutes each time, 40kHz, ultrasonic power density 50-100W / L;

[0058] Electrochemical method: current density 2-5A / dm 2 , pH = 1-3, copper sulfate electrolyte containing 0.1-0.5 mol / L H2SO4, electrolyte temperature 25±2°C, the anode adopts a platinum electrode with a purity of ≥99.9%, and the cathode adopts a copper foil with a thickness of 0.1-0.5 mm and a purity of ≥99.95%.

[0059] Specifically, by adjusting the concentration, temperature and corrosion time of the HNO3 solution, the corrosion degree of the copper powder can be precisely controlled, thereby obtaining micro-nano porous copper powder with different porosities and particle size distributions; ultrasonic cleaning can effectively remove corrosion products and impurities remaining on the surface of the copper powder, ensuring the purity and surface cleanliness of the micro-nano porous copper powder, and providing a good foundation for subsequent composite preparation processes; in the electrochemical method, the addition of H2SO4 can enhance the conductivity of the electrolyte and improve the efficiency of the electrochemical reaction. The platinum electrode has good chemical stability and conductivity and can withstand the redox reaction during the electrochemical reaction without being corroded. The high-purity copper foil serves as the cathode, which is conducive to the formation of uniform metal deposition and porous structure in the electrochemical reaction. At the same time, the appropriate current density can ensure the smooth progress of the electrochemical corrosion reaction and promote the formation of a uniform pore structure on the surface of the copper powder.

[0060] Add 1-5wt% reinforcement phase:

[0061] Ceramic particles: Al2O3 or SiC, particle size 0.5-5μm, graded by sieving method, using 800 mesh, 1200 mesh, and 2000 mesh screens for three-level screening, and the hardness is increased by 20-50HV;

[0062] Polymer material: polyimide or polyetheretherketone, with a molecular weight of 10 4 -10 5 , wear resistance increased by 2-5 times;

[0063] The reinforcing phase is evenly distributed by ultrasonic dispersion, and the absolute value of the zeta potential of the slurry after dispersion is ≥30mV, wherein the ultrasonic power is 200-500W, the time is 10-30min, the probe material is titanium alloy, and the diameter is 10-20mm.

[0064] Specifically, Al2O3 has good insulation properties, high temperature resistance and high hardness, SiC has excellent wear resistance, heat resistance and high hardness. The graded ceramic particles have uniform particle size distribution and can better combine with the matrix material to improve the comprehensive performance of the material; polyimide has excellent high temperature resistance, chemical stability and mechanical properties; polyetheretherketone has good wear resistance, corrosion resistance and dimensional stability. The polymer material can form a protective layer on the surface of the material, reduce material loss during friction, and extend the service life of the material; the absolute value of the Zeta potential of the slurry after dispersion is ≥30mV, which indicates that the reinforcing phase particles are evenly distributed in the matrix and have good stability.

[0065] Performance improvements are achieved through the following collaborative mechanisms:

[0066] The hierarchical porous structure provides high specific surface area and fast ion diffusion channels, with a specific surface area of ≥50m 2 / g, lithium ion diffusion coefficient ≥1×10 -9 cm 2 / s;

[0067] The nickel-titanium alloy coating and carbon nanotubes form a three-dimensional interpenetrating network structure in the matrix, with a thermal conductivity anisotropy ratio of ≤1.2, graphene inhibits grain boundary sliding, and the activation energy of grain boundary migration is ≥200kJ / mol;

[0068] The gradient pressure sintering process controls the grain size to 100-500nm, and the high temperature stability is ≤0.5% creep deformation, wherein the test condition is constant temperature loading at 300℃ for 100 hours.

[0069] Specifically, the high specific surface area increases the contact area between the material and the electrolyte, allowing more lithium ions to be adsorbed and desorbed on the material surface, thereby improving the specific capacity of the lithium-ion battery; the three-dimensional thermal conductive network can quickly and evenly conduct heat to all parts of the material, improving the thermal conductivity and heat dissipation performance of the material, ensuring uniform temperature distribution of the material under high-temperature working conditions, and avoiding local overheating; the fine grain size enhances the strength and toughness of the material, because the smaller the grains, the more grain boundaries there are, and the grain boundaries can hinder dislocation movement and improve the mechanical properties of the material.

[0070] Please see the attached Figure 1 A method for preparing a micro-nano porous copper powder composite metal material, used for the above-mentioned micro-nano porous copper powder composite metal material, the method comprises the following steps:

[0071] S1. Copper powder pretreatment: 100-400 μm electrolytic copper powder was etched in 5-15% nitric acid solution for 10-30 minutes with a stirring rate of 100-300 rpm, and then ultrasonically treated in 3-10% sodium hydroxide solution at a power of 100-300 W and a frequency of 20-40 kHz for 5-15 minutes with an ultrasonic probe diameter of 10-20 mm.

[0072] S2, porous treatment: in 10 -3 -10 -2 Under vacuum conditions of Pa, the temperature is raised to 600-800°C at a rate of 5-15°C / min and maintained for 1-3 hours, and an argon-hydrogen mixed gas with a volume ratio of 3:1-5:1 is introduced, wherein the purity of the argon is ≥99.999%, the purity of the hydrogen is ≥99.99%, and the gas flow rate is 10-50 sccm;

[0073] S3. Surface modification: Nickel-titanium alloy layer was deposited by pulsed electrodeposition for 30-120 minutes at a current density of 0.5-3 A / dm 2 , pulse frequency 100-500Hz, duty cycle 30-70%;

[0074] S4. Composite mixing: Mix the modified copper powder with the metal additive and functional phase, add 0.1-0.5% polyvinyl pyrrolidone solution, wherein the molecular weight of the polyvinyl pyrrolidone solution is 40,000-80,000, and the solvent is deionized water, and ball mill for 6-18 hours under argon protection, wherein the ball-to-material ratio is 5:1-10:1, the rotation speed is 200-400 rpm, and the residual oxygen content in the ball mill is ≤10ppm;

[0075] S5, gradient pressure sintering: After cold isostatic pressing to 200-500MPa, -2 -10 -1 Sintering in three stages under Pa vacuum:

[0076] The first stage: heating to 400-500℃ at 2-5℃ / min, keeping warm for 0.5-2 hours, applying axial pressure of 200-300MPa, with a holding pressure accuracy of ±5MPa, controlled by a servo hydraulic system;

[0077] The second stage: heating to 800-950℃ at 5-10℃ / min, keeping warm for 2-6 hours, and simultaneously applying isostatic pressure of 800-1000MPa. The pressure medium is argon with a purity of ≥99.999%. Multi-zone induction heating is used to ensure temperature uniformity of ±3℃.

[0078] The third stage: cool down to below 300℃ at 3-5℃ / min, gradually release the pressure to normal pressure, and maintain the vacuum degree ≤10 during the cooling process. -1 Pa;

[0079] S6. Post-treatment: 5-15% hydrofluoric acid etching for 1-5 minutes, wherein the stirring rate is 50-150 rpm, annealing at 500-700 ° C for 1-3 hours, wherein the annealing atmosphere is a nitrogen-hydrogen mixture with H2 accounting for 5-10%, and finally passivation treatment with 0.1-0.5% benzotriazole ethanol solution at 50-80 ° C for 10-30 minutes. After treatment, nitrogen purging and drying are carried out, wherein the nitrogen dew point is ≤-40 ° C.

[0080] Please see the attached Figure 1 The mold preheating temperature for cold isostatic pressing is 100-200℃, the preheating time is ≥30 minutes, the mold temperature difference before pressing is ≤±5℃, the mold material is cemented carbide, and the surface roughness Ra≤0.8μm;

[0081] The sintering furnace used for gradient pressure sintering adopts induction heating, wherein the frequency is 10-50kHz and the temperature fluctuation is controlled within ±2-5°C; the D50 of the powder after ball milling is 5-20μm and the particle size distribution span is (D90-D10) / D50≤1.2.

[0082] Specifically, the preheating treatment can effectively reduce the temperature difference between the mold and the powder, avoiding internal stress caused by uneven heating of the powder due to excessive temperature gradient during the pressing process. The temperature difference of the mold before pressing is ≤±5°C, which helps to ensure the stability of the pressing process, make the density of the pressed green body uniform, improve the quality of the green body, and the smooth surface is conducive to the flow and filling of the powder, improve the surface quality of the green body, and reduce subsequent processing steps. Induction heating can quickly and evenly transfer heat to the green body, improve sintering efficiency, and control the temperature fluctuation within ±2-5°C. Precise temperature control ensures the stability of the sintering process, avoids fluctuations in material properties due to excessively high or low temperatures, and ensures that the material can be fully densified during the sintering process. The appropriate particle size distribution helps to improve the fluidity of the powder, so that it can evenly fill the mold during the subsequent pressing process to form a green body with uniform density. The uniform powder particle size distribution can improve the sintering activity of the material, promote atomic diffusion and particle rearrangement during the sintering process, and improve the densification degree of the material. At the same time, the uniform particle size distribution is also conducive to improving the mechanical properties of the material, such as strength, hardness and toughness.

[0083] Please see the attached Figure 1 The relative density of the green body after gradient pressure sintering is ≥95%, the pore closure rate is ≥90%; the thickness of the surface oxide layer after passivation treatment is ≤10nm, and the salt spray corrosion resistance time is ≥500h.

[0084] Specifically, high relative density means that there are fewer pores inside the blank and the material is highly densified, which helps to improve the mechanical properties of the material, such as strength, hardness and wear resistance, while also improving the electrical conductivity and thermal conductivity of the material; most of the pores inside the blank have been effectively closed, which can prevent impurities and corrosive media from entering the material through the pores during use, thereby improving the corrosion resistance and oxidation resistance of the material. At the same time, the closed pores help to improve the fatigue strength of the material and reduce the initiation and expansion of cracks caused by stress concentration caused by the pores; the thinner oxide layer can effectively protect the material matrix from further oxidation and corrosion without significantly increasing the surface roughness of the material; the material has good corrosion resistance in corrosive environments such as salt spray and can resist the erosion of corrosive media for a long time.

[0085] An application of a micro-nano porous copper powder composite metal material, characterized in that it is applied to high-power heat dissipation devices, lithium-ion battery negative electrodes or electromagnetic shielding materials.

[0086] Specifically, the composite metal material performs well in high-power heat dissipation devices, with a thermal conductivity of up to 200-400W / m·K. It can quickly conduct the heat generated by the device to the heat dissipation surface and dissipate it, effectively reducing the device's operating temperature, ensuring stable operation of electronic components in high-temperature environments and extending their service life; the contact thermal resistance is as low as 0.01-0.05cm 2 ·K / W, which makes the heat transfer between the material and the device more efficient, reduces the accumulation of heat at the interface, and further improves the heat dissipation efficiency; when used as a negative electrode material for lithium-ion batteries, its specific capacity is as high as 800-1200mAh / g. Under the conditions of a charge and discharge rate of 0.1C and a voltage window of 0.01-3Vvs.Li+ / Li, it can store and release a large amount of lithium ions, providing long-lasting battery life; under a constant temperature test at 25°C, after 100 cycles, the capacity retention rate can still reach 85-95%, indicating that the material has good structural stability and reversibility. It can maintain excellent electrochemical properties during multiple charge and discharge processes, providing reliable protection for the long-term stable use of lithium-ion batteries; in the field of electromagnetic shielding, the composite metal material exhibits a shielding effectiveness of ≥60dB, which can effectively block and attenuate the propagation of electromagnetic waves, prevent the impact of electromagnetic interference on electronic equipment, and is suitable for various occasions with high requirements for electromagnetic compatibility. Its shielding effectiveness covers the frequency band range of 1-10GHz, meeting the electromagnetic shielding needs of modern electronic equipment at different frequencies, ensuring the normal operation of the equipment in complex electromagnetic environments, and improving the reliability and effectiveness of electromagnetic shielding.

[0087] Example 1: Basic formula optimization and hierarchical pore structure realization

[0088] 1. Technical Solution

[0089] 1. Material composition:

[0090] Substrate: 200 ± 50 nm micro-nanoporous copper powder (porosity 60%, pore diameter 50-150 nm), prepared by chemical etching using 5 mol / L HNO3 at 60°C for 4 hours, followed by ultrasonic cleaning with deionized water three times (5 minutes each, 40 kHz);

[0091] Metal additives: 10wt% aluminum powder (particle size 50-80nm), 8wt% nickel powder (particle size 80-120nm);

[0092] Functional additives: 3wt% titanium powder (particle size 60-100nm), 2wt% graphene (number of layers 4-6), 1.5wt% carbon nanotubes (aspect ratio 800-1200, outer diameter 20-30nm).

[0093] 2. Preparation process:

[0094] 1. Copper powder pretreatment: 300 μm electrolytic copper powder was etched in 10% nitric acid for 20 minutes (stirring rate 200 rpm), followed by ultrasonic treatment in 5% sodium hydroxide solution for 10 minutes (power 200 W, frequency 30 kHz, probe diameter 15 mm) to remove surface oil and oxide layer and improve the uniformity of subsequent porous treatment;

[0095] 2. Porosification treatment: Heat the powder to 700°C at a rate of 10°C / min and keep the temperature for 2 hours under a vacuum of 10-3Pa. Then, introduce a 4:1 mixed gas of Ar / H2 (flow rate 30 sccm). By precisely controlling the heating rate and gas flow rate, a uniform hierarchical pore structure is formed on the micro-nano porous copper powder.

[0096] 3. Surface modification: A nickel-titanium alloy layer was deposited on the surface of the copper powder using pulse electrodeposition. The deposition time was 60 minutes and the current density was 1.5 A / dm 2 , pulse frequency 300Hz, duty cycle 50%, forming an alloy coating with a thickness of 200-300 nanometers, enhancing surface conductivity and corrosion resistance;

[0097] 4. Composite mixing: Mix the modified copper powder with metal additives and functional additives, add 0.3% polyvinyl pyrrolidone solution (molecular weight 60,000), and ball mill with zirconium oxide grinding balls (diameter 3 mm) under argon protection for 12 hours, with a ball-to-material ratio of 8:1 and a rotation speed of 300 rpm to ensure that all components are fully mixed and avoid oxidation;

[0098] 5. Gradient pressure sintering: After cold isostatic pressing to 350MPa, sintering is carried out in three stages under a vacuum degree of 10-2Pa:

[0099] The first stage: heating to 400℃ at 3℃ / min, keeping warm for 1 hour, applying axial pressure of 250MPa, reducing interfacial stress through low-temperature preloading, and initially forming a dense structure;

[0100] The second stage: heating to 900°C at 8°C / min, holding for 4 hours, and simultaneously applying an isostatic pressure of 900 MPa to promote atomic diffusion and grain growth using high temperature and high pressure to achieve material densification;

[0101] The third stage: cool down to below 300℃ at 4℃ / min, gradually release the pressure to normal pressure, and maintain the vacuum degree ≤10 - 1 Pa, to ensure the stability of the sintered green body during cooling.

[0102] 3. Parameter optimization basis:

[0103] 1. The hierarchical pore ratio (60% main pores + 25% secondary pores) has been verified through multiple simulations and experiments to effectively balance specific surface area and mechanical strength. The main pores provide fast ion transport channels, while the secondary pores increase reactive sites.

[0104] 2. The low-temperature pre-pressing (400°C) of gradient pressure sintering can eliminate the initial gaps and stress between powders. The high-temperature and high-pressure (900°C) stage promotes the full diffusion and recrystallization of metal atoms, so that the material reaches a high relative density (≥98%) and improves the overall performance.

[0105] 4. Comparative Example 1: Conventional Sintering Process

[0106] 1. Technical solution

[0107] Material composition:

[0108] Matrix: micro-nano porous copper powder with a particle size of 200±50nm (porosity 60%, pore diameter 50-150nm);

[0109] Metal additives: 10wt% aluminum powder, 8wt% nickel powder;

[0110] Functional additives: 3wt% titanium powder, 2wt% graphene (4-6 layers), 1.5wt% carbon nanotubes (aspect ratio 800-1200).

[0111] Preparation process:

[0112] Copper powder pretreatment: the same as in Example 1 (10% nitric acid etching for 20 minutes, 5% sodium hydroxide ultrasonic treatment for 10 minutes);

[0113] Porosification treatment: heating to 700°C at 10°C / min under vacuum of 10-3 Pa and holding for 2 hours, introducing a 4:1 Ar / H2 mixed gas (flow rate 30 sccm);

[0114] Conventional sintering: directly raise the temperature to 900°C at 10°C / min, keep it at this temperature for 4 hours, and apply an isostatic pressure of 900 MPa (no gradient pressurization stage).

[0115] Parameter optimization basis:

[0116] Conventional sintering uses a single high-temperature stage to simulate traditional powder metallurgy processes without introducing low-temperature pre-pressing and gradient temperature control.

[0117] V. Implementation Effect Verification:

[0118] Performance indicators Example 1 Comparative Example 1 Test standards Conductivity (%IACS) 102 85 ASTM B193 Tensile strength (MPa) 480 320 GB / T228.1 <![CDATA[Lithium ion diffusion coefficient (cm 2 / s)]]> <![CDATA[2.3×10 -9 ]]> <![CDATA[0.8×10 -9 ]]> potentiostatic intermittent titration Porosity uniformity (%) 92 78 ISO15901-1 Grain size (nm) 150±30 400±100 EBSD analysis

[0119] Summary: In Example 1, the electrical conductivity is increased by 20% (compared with conventional sintering) and the tensile strength is increased by 50% through the hierarchical pore design and gradient sintering process, verifying the synergistic enhancement effect of the hierarchical structure on conductivity and mechanical properties.

[0120] Example 2: Reinforced phase composite and interface strengthening

[0121] 1. Technical Solution

[0122] 1. Material composition:

[0123] On the basis of Example 1, 3 wt% SiC ceramic particles (particle size 1-3 μm, purity ≥99%, XRF detection according to GB / T16597, detection limit 0.01%), 2 wt% polyetheretherketone (molecular weight 5×10 4 , glass transition temperature 140°C, melt index 8g / 10min, ASTM D1238 test).

[0124] 2. Process improvement:

[0125] Ultrasonic dispersion: Before mixing the reinforcement phase with the copper powder matrix, ultrasonic dispersion is performed at 400W power for 20 minutes (Zeta potential -45mV) to ensure that the ceramic particles and polymer materials are evenly distributed in the metal matrix to avoid agglomeration;

[0126] 3. Ball milling optimization: Use zirconia grinding balls (5mm in diameter), a ball-to-material ratio of 8:1, and a speed of 350rpm for 15 hours. Use high-energy ball milling to form a nano-scale composite structure between the reinforcement phase and the metal powder to enhance the interface bonding;

[0127] 4. Passivation treatment: Treat with 0.3% benzotriazole ethanol solution at 50-60°C for 20 minutes (pH = 7.0) to form a dense passivation film and improve surface corrosion resistance.

[0128] 2. Parameter optimization basis:

[0129] SiC particle size ≤ 3 μm can avoid stress concentration, and its high hardness (≥ 2000 HV) forms a reinforced composite with the copper matrix to improve the wear resistance of the material; the molecular weight of polyetheretherketone is 5×10 4 Ensure thermal stability during high-temperature sintering, form a flexible reinforcement phase, and improve the impact resistance of the material;

[0130] The absolute value of Zeta potential ≥30mV (tested according to GB / T32672 standard) ensures the dispersion stability of the slurry, so that the reinforcing phase can be evenly embedded in the metal matrix during the ball milling process, forming a good interface bonding.

[0131] 3. Comparative Example 2: No Reinforcement Phase

[0132] 1. Technical solution

[0133] Material composition:

[0134] The matrix and metal / functional additives are the same as those in Example 1 (without SiC ceramic particles and polyetheretherketone).

[0135] Preparation process:

[0136] Composite mixing: Omit the reinforcing phase addition step and directly ball mill the mixture;

[0137] Other processes: the same as in Example 2 (including gradient pressure sintering and passivation treatment).

[0138] Parameter optimization basis:

[0139] Removal of reinforcement phase to compare its effect on hardness, wear resistance and corrosion resistance

[0140] 4. Implementation effect verification:

[0141] Performance indicators Example 2 Comparative Example 2 Test standards Hardness (HV) 220 180 ISO6507 <![CDATA[Wear resistance (volume loss / mm 3 )]]> 0.12 0.35 ASTMG133 (10N load) Salt spray resistance time (h) 620 350 GB / T10125 <![CDATA[Charpy impact toughness (J / cm 2 )]]> 18 12 GB / T229 (V-notch) Interface bonding strength (GPa) 15 8 Nanoindentation method, indentation rate 0.05nm / s

[0142] Summary: In Example 2, the hardness is increased by 22%, the wear resistance is increased by 65%, the corrosion resistance is increased by 77%, and the impact toughness is increased by 50% through the ceramic / polymer reinforcement phase composite. This shows that the multi-scale reinforcement phase design can effectively break through the performance limitations of traditional composite materials and expand the applicability of the material under different working conditions.

[0143] Example 3: High-temperature stability optimization and three-dimensional thermal network construction

[0144] 1. Technical Solution

[0145] 1. Process improvement:

[0146] Surface modification: A nickel-titanium alloy layer was deposited on the copper powder surface using pulsed electrodeposition with a duty cycle of 50%, a reverse current of 15%, and a deposition time of 90 minutes. This formed a gradient alloy coating with a thickness of 300-400 nm, improving the surface's high-temperature resistance and thermal conductivity. The dendrite suppression effect was verified using electrochemical impedance spectroscopy (EIS) with a frequency range of 0.1 Hz to 100 kHz and an amplitude of 10 mV.

[0147] Sintering control: Multi-zone induction heating (frequency 30kHz, power density 8W / cm 3 ), temperature uniformity is controlled within ±2°C to ensure that all parts of the material are heated evenly during sintering and inhibit abnormal grain growth;

[0148] Annealing process: Annealing at 650°C for 2 hours in a nitrogen-hydrogen mixture (8% H2) atmosphere to optimize the internal stress distribution of the material and improve high-temperature stability.

[0149] 2. Structural features:

[0150] The grain size is 250±50nm (analyzed by EBSD), and the uniform and fine grain structure enhances the high temperature strength of the material.

[0151] Graphene is evenly distributed along the grain boundaries (observed by transmission electron microscopy), and together with carbon nanotubes, it constructs a three-dimensional thermal conductive network, improving thermal conductivity and thermal stability.

[0152] The nickel-titanium alloy coating forms a metallurgical bond with the substrate, and the interface bonding strength is ≥180MPa (micro-area hardness test).

[0153] 2. Parameter optimization basis:

[0154] The reverse current of pulsed electrodeposition can effectively eliminate dendrite growth, improve the density and bonding strength of the coating, and ensure that the coating does not peel off at high temperatures;

[0155] Multi-zone induction heating reduces temperature gradients through precise temperature field control, ensuring uniform grain growth and avoiding performance degradation caused by oversized grains.

[0156] The annealing process optimizes the residual stress inside the material, allowing graphene and carbon nanotubes to form a stable heat conduction channel in the matrix, while activating the high-temperature protection performance of the nickel-titanium alloy coating.

[0157] 3. Comparative Example 3: One-way Heating Process

[0158] 1. Technical solution

[0159] Material composition: same as Example 1.

[0160] 2. Preparation process:

[0161] Surface modification: DC electrodeposition of nickel-titanium alloy layer (no pulse parameters, current density 3A / dm 2 );

[0162] Sintering control: Use traditional resistance heating (not induction heating), one-way heating to 900℃ (heating rate 10℃ / min), keep warm for 4 hours, temperature fluctuation ±15℃;

[0163] Annealing process: same as Example 3.

[0164] 3. Parameter optimization basis:

[0165] Unidirectional heating leads to uneven temperature distribution and coarsening of grain size (500-800nm).

[0166] 4. Implementation effect verification:

[0167] Performance indicators Example 3 Comparative Example 3 Test standards Thermal conductivity (W / m·K) 380 250 ASTME1461 High temperature creep deformation rate (300℃ / 100h) 0.4％ 1.2％ GB / T2039 Thermal cycle stability (times) >500 200 GB / T4338 Grain boundary migration activation energy (kJ / mol) 210 150 In situ hot stage transmission electron microscopy <![CDATA[Coefficient of thermal expansion (×10 -6 / K)]]> 12 18 GB / T4339 Grain size (nm) 250±50 600±200 EBSD analysis (step size 50 nm)

[0168] Summary: In Example 3, through the construction of a three-dimensional thermal conductive network and grain boundary control, the thermal conductivity is increased by 52%, the high-temperature creep deformation rate is reduced by 67%, and the thermal cycling stability is improved by 150%, verifying the significant improvement of high-temperature stability by gradient sintering and interface optimization.

[0169] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A composite metal material based on micro-nano porous copper powder, characterized by: The invention is composed of the following components: a micro-nano porous copper powder with a particle size of 50-500 nanometers, a porosity of 30-80%, and a pore diameter of 20-200 nanometers, formed by chemical corrosion or electrochemical treatment of electrolytic copper powder as a matrix; and the following additive components: metal additives: 5-20wt% of aluminum powder and 3-15wt% of nickel powder; functional additives: 1-8wt% of titanium powder, 0.5-5wt% of graphene, and 0.3-3wt% of carbon nanotubes; a nickel-titanium alloy coating with a thickness of 50-500 nanometers is formed on the surface of the micro-nano porous copper powder by electrochemical deposition, and the aluminum powder filling rate inside the pores is ≥85%.

2. The micro-nano porous copper powder composite metal material according to claim 1, characterized in that: The micro-nano porous copper powder comprises a hierarchical pore structure, wherein primary pores of 50-200 nanometers account for 40-70% of the total volume, and secondary pores of 10-50 nanometers account for 20-30%; The nickel-titanium alloy coating on the surface forms a gradient interface bonding layer with the aluminum powder inside the pores, with a thickness of 10-30 nanometers and an interface bonding strength of ≥150MPa; The number of graphene layers is 2-8, the aspect ratio of carbon nanotubes is 500-2000, and the outer diameter is 10-50 nanometers.

3. The micro-nano porous copper powder composite metal material according to claim 1, characterized in that: In the microstructure: Aluminum powder fills the pores to form a continuous conductive network, and the nickel-titanium alloy coating and carbon nanotubes form a pinning effect at the interface; Electrical conductivity ≥98% IACS, thermal conductivity ≥350W / m·K, tensile strength ≥450MPa, hardness ≥180HV.

4. The micro-nano porous copper powder composite metal material according to claim 1, characterized in that: Micro-nano porous copper powder is prepared by any of the following methods: Chemical etching method: using 3-8 mol / L HNO3 solution, 50-80℃ etching for 2-6 hours, followed by ultrasonic cleaning with deionized water for 3 times, 5 minutes each time, 40kHz, ultrasonic power density 50-100W / L; Electrochemical method: current density 2-5A / dm 2 , pH = 1-3, copper sulfate electrolyte containing 0.1-0.5 mol / L H2SO4, electrolyte temperature 25±2°C, the anode adopts a platinum electrode with a purity of ≥99.9%, and the cathode adopts a copper foil with a thickness of 0.1-0.5 mm and a purity of ≥99.95%.

5. The micro-nano porous copper powder composite metal material according to claim 1, characterized in that: Add 1-5wt% reinforcement phase: Ceramic particles: Al2O3 or SiC, particle size 0.5-5μm, graded by sieving method, using 800 mesh, 1200 mesh, and 2000 mesh screens for three-level screening, and the hardness is increased by 20-50HV; Polymer material: polyimide or polyetheretherketone, with a molecular weight of 10 4 -10 5 , wear resistance is improved by 2-5 times; the reinforcing phase is evenly distributed by ultrasonic dispersion, and the absolute value of the zeta potential of the slurry after dispersion is ≥30mV, wherein the ultrasonic power is 200-500W, the time is 10-30min, the probe material is titanium alloy, and the diameter is 10-20mm.

6. The micro-nano porous copper powder-based composite metal material according to claim 1, characterized in that: Performance improvements are achieved through the following collaborative mechanisms: The hierarchical porous structure provides high specific surface area and fast ion diffusion channels, with a specific surface area of ≥50m 2 / g, lithium ion diffusion coefficient ≥1×10 -9 cm 2 / s; The nickel-titanium alloy coating and carbon nanotubes form a three-dimensional interpenetrating network structure in the matrix, with a thermal conductivity anisotropy ratio of ≤1.2, graphene inhibits grain boundary sliding, and the grain boundary migration activation energy is ≥200kJ / mol; The gradient pressure sintering process controls the grain size to 100-500nm, and the high temperature stability is ≤0.5% creep deformation, wherein the test condition is constant temperature loading at 300℃ for 100 hours.

7. A method for preparing a composite metal material based on micro-nano porous copper powder, characterized in that: A micro-nano porous copper powder composite metal material according to any one of claims 1 to 6, the method comprising the following steps: S1. Copper powder pretreatment: 100-400 μm electrolytic copper powder was etched in 5-15% nitric acid solution for 10-30 minutes with a stirring rate of 100-300 rpm, and then ultrasonically treated in 3-10% sodium hydroxide solution at a power of 100-300 W and a frequency of 20-40 kHz for 5-15 minutes with an ultrasonic probe diameter of 10-20 mm. S2, porous treatment: in 10 -3 -10 -2 Under vacuum conditions of Pa, the temperature is raised to 600-800°C at a rate of 5-15°C / min and maintained for 1-3 hours, and an argon-hydrogen mixed gas with a volume ratio of 3:1-5:1 is introduced, wherein the purity of the argon is ≥99.999%, the purity of the hydrogen is ≥99.99%, and the gas flow rate is 10-50 sccm; S3. Surface modification: Nickel-titanium alloy layer was deposited by pulse electrodeposition for 30-120 minutes at a current density of 0.5-3 A / dm 2 , pulse frequency 100-500Hz, duty cycle 30-70%; S4. Composite mixing: Mix the modified copper powder with the metal additive and functional phase, add 0.1-0.5% polyvinyl pyrrolidone solution, wherein the molecular weight of the polyvinyl pyrrolidone solution is 40,000-80,000, and the solvent is deionized water. Ball milling is carried out under argon protection for 6-18 hours, wherein the ball-to-material ratio is 5:1-10:1, the rotation speed is 200-400 rpm, and the residual oxygen content in the ball mill is ≤10ppm; S5, gradient pressure sintering: After cold isostatic pressing to 200-500MPa, -2 -10 -1 Sintering in three stages under Pa vacuum: The first stage: heating to 400-500℃ at 2-5℃ / min, keeping warm for 0.5-2 hours, applying axial pressure of 200-300MPa, with a holding pressure accuracy of ±5MPa, controlled by a servo hydraulic system; The second stage: heating to 800-950℃ at 5-10℃ / min, keeping warm for 2-6 hours, and simultaneously applying isostatic pressure of 800-1000MPa. The pressure medium is argon with a purity of ≥99.999%. Multi-zone induction heating is used to ensure temperature uniformity of ±3℃. The third stage: cool down to below 300℃ at 3-5℃ / min, gradually release the pressure to normal pressure, and maintain the vacuum degree ≤10-1Pa during the cooling process; S6. Post-treatment: 5-15% hydrofluoric acid etching for 1-5 minutes, wherein the stirring rate is 50-150 rpm, annealing at 500-700 ° C for 1-3 hours, wherein the annealing atmosphere is a nitrogen-hydrogen mixture with H2 accounting for 5-10%, and finally passivation treatment with 0.1-0.5% benzotriazole ethanol solution at 50-80 ° C for 10-30 minutes. After treatment, nitrogen purging and drying are carried out, wherein the nitrogen dew point is ≤-40 ° C.

8. The method for preparing a micro-nano porous copper powder composite metal material according to claim 7, characterized in that: The mold preheating temperature for cold isostatic pressing is 100-200℃, the preheating time is ≥30 minutes, the mold temperature difference before pressing is ≤±5℃, the mold material is cemented carbide, and the surface roughness Ra ≤0.8μm; The sintering furnace used for gradient pressure sintering adopts induction heating, wherein the frequency is 10-50kHz and the temperature fluctuation is controlled within ±2-5°C; the D50 of the powder after ball milling is 5-20μm and the particle size distribution span is (D90-D10) / D50≤1.

2.

9. The method for preparing a micro-nano porous copper powder composite metal material according to claim 7, characterized in that: The relative density of the green body after gradient pressure sintering is ≥95%, and the pore closure rate is ≥90%; the thickness of the surface oxide layer after passivation treatment is ≤10nm, and the salt spray corrosion resistance time is ≥500h.

10. An application of the micro-nano porous copper powder composite metal material according to any one of claims 1 to 6, characterized in that: Applied to high-power heat dissipation devices, lithium-ion battery negative electrodes or electromagnetic shielding materials.

Images