Preparation method of high-strength and high-thermal-conductivity copper-based composite material and high-strength and high-thermal-conductivity copper-based composite material

Abstract

The invention belongs to the technical field of diamond copper composite materials, and particularly relates to a preparation method of a high-strength and high-thermal-conductivity copper-based composite material and the high-strength and high-thermal-conductivity copper-based composite material. The preparation method of the high-strength and high-thermal-conductivity copper-based composite material comprises the following steps that (1) diamond particles and copper-aluminum alloy powder are mixed and then subjected to heat treatment in an inert atmosphere, and diamond-copper mixed powder is obtained; and 2) mixing the diamond-copper mixed powder obtained in the step 1) with an oxygen source, performing compression molding, and performing internal oxidation reduction sintering. Aluminum carbide and Cu-Al-C are generated on the surface of diamond in situ through interface reaction to improve the interface bonding strength of the diamond and a copper matrix, Al2O3 nanoparticles are generated in situ through internal oxidation-reduction-sintering, the interface bonding capacity and the heat conduction performance are further improved, and then preparation of the high-strength and high-heat-conduction copper-based composite material is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of diamond copper composite material, and particularly relates to a preparation method of high-strength high-thermal-conductivity copper-based composite material and the high-strength high-thermal-conductivity copper-based composite material. BACKGROUND

[0002] Modern electronic equipment not only requires heat dissipation materials to have higher thermal conductivity, but also requires these materials to be able to play a role in extremely limited space, while taking into account lightweight and cost-effectiveness. Diamond copper composite material combines the advantages of high thermal conductivity and low thermal expansion coefficient of diamond, and is widely used in electronic packaging, aerospace and other fields.

[0003] At present, the preparation methods of diamond copper composite material mainly include powder metallurgy, liquid phase infiltration, and discharge plasma sintering. However, the traditional preparation methods have the following defects: 1) weak interface bonding: the wettability between diamond and copper is poor, and voids or brittle phases (such as graphitized carbon) are easily formed at the interface, resulting in a decrease in mechanical properties; 2) thermal conduction bottleneck: impurities are easily introduced on the surface of the processed diamond, reducing the thermal conduction efficiency.

[0004] Diamond surface modification and matrix alloying are common means to improve the interface bonding strength. Matrix alloying refers to adding carbide elements to the metal matrix copper, so that a carbide coating is formed at the diamond / copper interface during the infiltration process, thereby improving the interface bonding strength between the diamond-copper two phases. However, due to the difficulty in controlling the content of strong carbide elements, it is difficult to form a complete carbide coating at the interface, and too much carbide coating reduces the thermal conductivity of the composite material, and the alloying elements partially dissolve into the copper matrix, resulting in a decrease in the thermal conductivity of the copper matrix.

[0005] Diamond surface modification refers to coating carbide on the surface of diamond, which can form a chemical bond with diamond and become a binder and filler at the diamond-copper interface, thereby effectively reducing the interface thermal resistance and improving the thermal conductivity of the composite material. At present, the commonly used carbide forming elements are Cr, Ti, Mu, B and W, and the commonly used methods are magnetron sputtering, molten salt method and vacuum micro evaporation, resulting in a complex preparation process of diamond coating and high cost, and the mechanical properties and thermal conductivity are still poor. SUMMARY

[0006] The purpose of the present application is to provide a preparation method of high-strength high-thermal-conductivity copper-based composite material, which solves the problems of poor mechanical properties and thermal conductivity and complex preparation process of diamond coating in the existing preparation method.

[0007] The second purpose of the present application is to provide a high-strength high-thermal-conductivity copper-based composite material, which solves the problems of poor mechanical properties and thermal conductivity and complex preparation process of diamond coating in the existing copper-based composite material.

[0008] To solve the above technical problems, the technical scheme of the preparation method of the high-strength and high-thermal-conductivity copper-based composite material of the present application is as follows: A preparation method of a high-strength and high-thermal-conductivity copper-based composite material, comprising the following steps: 1) mixing diamond particles and copper-aluminum alloy powder and then performing heat treatment at 700-900 DEG C in an inert atmosphere to obtain diamond copper mixed powder; 2) mixing the diamond copper mixed powder obtained in step 1) with an oxygen source and then performing compression molding and internal oxidation reduction sintering.

[0009] The present application is an improvement on the prior art, and the provided preparation method of a high-strength and high-thermal-conductivity copper-based composite material can improve the interfacial bonding strength of diamond and copper matrix by performing heat treatment at 700-900 DEG C to cause interfacial reaction of diamond and copper-aluminum alloy to generate Al4C3 and Cu-Al-C mixture in situ; and the internal oxidation of the residual aluminum element in the copper-aluminum alloy with the oxygen element in the oxygen source generates Al2O3 nanoparticles in situ, which not only fills the interfacial gap but also serves as a thermal conduction path to improve the thermal conductivity of the composite material; and the unreacted oxygen source is reduced by reduction, and finally a high-strength and high-thermal-conductivity copper-based composite material is obtained by sintering.

[0010] The copper-based composite material prepared by the provided preparation method of a high-strength and high-thermal-conductivity copper-based composite material has excellent mechanical properties and thermal conductivity, and the tensile strength is above 350 MPa and the thermal conductivity is above 620 W / m•K. The provided preparation method improves the interfacial bonding strength by in-situ generation of aluminum carbide and Cu-Al-C mixture through interfacial reaction and internal oxidation, and generates nano-Al2O3 to improve the interfacial bonding and thermal conductivity, without the need for plating a transition layer or complex alloying treatment on the surface of the diamond, and the process is simple, the cost is reduced, and it is suitable for existing powder metallurgy production lines.

[0011] To further improve the thermal conductivity and mechanical properties of the composite material, preferably, the volume ratio of the diamond particles to the copper-aluminum alloy powder in step 1) is (50-70):(50-30), and the aluminum content in the copper-aluminum alloy powder is ≥1wt%. With the increase of the aluminum content, the content of the in-situ generated Al2O3 nanoparticles increases, and the stability of the composite material also greatly improves, which can significantly improve the thermal fatigue resistance of the material.

[0012] To further improve the performance of subsequent internal oxidation reduction sintering, preferably, the aluminum content in the copper-aluminum alloy powder is 1-2wt%. Too high aluminum content can easily lead to incomplete internal oxidation.

[0013] To further improve the interfacial bonding ability of diamond and copper matrix, preferably, the temperature of the heat treatment in step 1) is 700-750 DEG C, and the heat treatment time is 1-4h.

[0014] In order to further reduce the energy consumption, preferably, the time of the heat treatment is 1-1.2h.

[0015] In order to further improve the generation of Al2O3 nanoparticles, preferably, the molar ratio of the oxygen element of the oxygen source in the step 2) to the aluminum element in the copper-aluminum alloy powder in the step 1) is (1.2-1.5):1.

[0016] In order to further improve the interface bonding strength, preferably, the surface of the diamond particles in the step 1) is plated with an aluminum layer, and the thickness of the aluminum layer is 1-1.5μm.

[0017] In order to further improve the internal oxidation-reduction-sintering performance, preferably, the temperature of the internal oxidation in the step 2) is 850-950℃, the time of the internal oxidation is 2-6h; the temperature of the reduction is 880-980℃, the time of the reduction is 2-6h; the temperature of the sintering is 900-960℃, and the time of the sintering is 2-6h.

[0018] In order to further improve the thermal conductivity of the composite material, preferably, the oxygen source in the step 2) is cuprous oxide. The oxygen element in the cuprous oxide forms Al2O3 nanoparticles with the aluminum element in the internal oxidation process, and is reduced into elemental copper in the reduction process, and does not introduce new impurities.

[0019] The technical scheme of the high-strength high-thermal-conductivity copper-based composite material of the present application is as follows: The high-strength high-thermal-conductivity copper-based composite material obtained by the preparation method of the high-strength high-thermal-conductivity copper-based composite material.

[0020] The high-strength high-thermal-conductivity copper-based composite material of the present application is obtained by the preparation method, and has excellent mechanical properties and thermal conductivity, with a tensile strength of more than 350MPa and a thermal conductivity of more than 620 W / m•K. DETAILED DESCRIPTION

[0021] The technical concept of the preparation method of the high-strength high-thermal-conductivity copper-based composite material provided by the present application is as follows: The prior art improves the interface bonding strength by surface modification of diamond and alloying of the matrix, but the content of strong carbide elements in the alloying matrix is uncontrollable, the surface modification needs to be plated with carbide on the surface of diamond, the process is complex and the cost is high, and the mechanical properties and thermal conductivity are poor.

[0022] The present application generates aluminum carbide and Cu-Al-C in situ on the surface of diamond through interface reaction to improve the interface bonding strength of diamond and copper matrix, and generates Al2O3 nanoparticles in situ through internal oxidation-reduction-sintering to further improve the interface bonding capacity and thermal conductivity.

[0023] The application provides a preparation method of high-strength high-thermal-conductivity copper-based composite material. 1) raw material mixing: diamond particles and copper-aluminum alloy powder are ball-milled to obtain mixed powder.

[0024] The particle size of the selected diamond particles is not higher than 500 μm, and more preferably not higher than 300 μm; the particle size of the copper-aluminum alloy powder is 5-100 μm, and more preferably 5-80 μm. The diamond can be natural or artificial diamond. The diamond particles can be washed to remove surface impurities, and the solution used in the washing process is commercially available concentrated sulfuric acid and hydrogen peroxide. The ball-milling time is 60-120 min.

[0025] Preferably, the volume ratio of the diamond particles to the copper-aluminum alloy powder is (50-70):(50-30), and the content of aluminum in the copper-aluminum alloy powder is ≥1 wt%. More preferably, the content of aluminum in the copper-aluminum alloy powder is 1-2 wt%.

[0026] Preferably, the diamond particles are plated with an aluminum layer, and the thickness of the aluminum layer is 1-1.5 μm. It can be understood that the surface of the diamond particles is plated according to the prior art. Specifically, the aluminum layer is plated on the surface of the diamond particles by using magnetron sputtering.

[0027] 2) interface reaction heat treatment: the mixed powder obtained in step 1) is subjected to heat treatment at 700-900 ℃ in an inert atmosphere to make the diamond particles and the copper-aluminum alloy powder react at the interface to generate aluminum carbide and Cu-Al-C, so as to improve the interface bonding strength of the diamond and the copper matrix; after sintering, the product is naturally cooled to room temperature to obtain a diamond copper mixed powder.

[0028] The inert atmosphere is argon or nitrogen, and the purity of the argon or nitrogen is ≥99.999%.

[0029] Preferably, the heat treatment temperature is 700-750 ℃, and the heat treatment time is 1-4 h. More preferably, the heat treatment time is 1-1.2 h.

[0030] It can be understood that the diamond copper mixed powder product after heat treatment can be adhered or partially agglomerated, and can be further crushed to meet the requirements of powder metallurgy on the particle size of the raw material.

[0031] 3) The diamond copper mixed powder obtained in step 2) is mixed with an oxygen source and then pressed to form an internal oxidation and reduction sintering product. In the internal oxidation process, the remaining aluminum in the copper-aluminum alloy powder is in-situ internally oxidized with oxygen in the oxygen source to generate Al2O3 nanoparticles, which not only fills the interface gap but also serves as a thermal conduction path to improve the thermal conductivity of the composite material. In the reduction process, the oxygen source is reduced.

[0032] It can be understood that the internal oxidation-reduction sintering includes an internal oxidation process, a reduction process and a sintering process; the gas atmosphere in the internal oxidation process is an inert gas atmosphere, and the pressure of the inert gas atmosphere is 2-5 atm. The gas atmosphere in the reduction process and the sintering process is a hydrogen gas atmosphere, and the pressure of the hydrogen gas atmosphere is 2-5 atm.

[0033] In the formula, the oxygen source is cuprous oxide particles (Cu2O), and the oxygen element in the cuprous oxide is formed into Al2O3 nanoparticles with the aluminum element in the internal oxidation process and is reduced into elemental copper in the reduction process, without introducing new impurities.

[0034] The diamond copper mixed powder and the oxygen source are mixed and pressed into a shape by cold isostatic pressing, and the density of the green body after the pressing is 4.5-5.5 g / cm 3 A binder can be added during the mixing to enhance the pressing ability, and the addition amount of the binder is 1-3 wt% of the total mass of the diamond copper mixed powder and the oxygen source, and the binder is selected from one or more of phenolic resin, polyvinyl alcohol. The pressure during the pressing is 200-500 MPa. The pressing can be performed according to the required product shape.

[0035] Preferably, the molar ratio of the oxygen element of the oxygen source to the aluminum element in the copper-aluminum alloy powder in step 1) is (1.2-1.5):1. More preferably, the molar ratio is 1.2:1.

[0036] Preferably, the internal oxidation temperature is 850-950℃, and the internal oxidation time is 2-6h. More preferably, the internal oxidation temperature is 850-920℃.

[0037] Preferably, the reduction temperature is 880-980℃, and the reduction time is 2-6h. More preferably, the reduction temperature is 880-910℃.

[0038] Preferably, the sintering temperature is 900-960℃, and the sintering time is 2-6h. More preferably, the sintering temperature is 900-950℃.

[0039] Specifically, the sintering temperature is 20-50℃ higher than the reduction temperature, so as to better perform powder metallurgy sintering. After the sintering is completed, the sintered body is cooled to 200-300℃ in the furnace to obtain the high-strength high-thermal-conductivity copper-based composite material.

[0040] The embodiments of the application are further described below in combination with specific examples. The chemical reagents involved in the following examples are all commercially available conventional goods, unless otherwise specified.

[0041] First, the preparation method of the high-strength high-thermal-conductivity copper-based composite material of the application and the specific embodiments of the high-strength high-thermal-conductivity copper-based composite material Example 1 The preparation method of the high-strength and high-thermal-conductivity copper-based composite material of the embodiment is as follows: 1) Raw material mixing: diamond particles with a particle size of 100-300 μm are washed with concentrated sulfuric acid and hydrogen peroxide to remove surface impurities, and then the acid-washed diamond particles and 10-50 μm Cu-Al alloy powder (Al content 1 wt%) are ball-mixed at a volume ratio of 60:40 for 90 min to obtain a mixed powder.

[0042] 2) Interface reaction heat treatment: the mixed powder obtained in step 1) is placed in a sintering furnace and heated to 700℃ under an argon atmosphere (purity ≥ 99.999%) for 60 min. At this time, the aluminum in the copper-aluminum alloy powder is partially dissolved and reacts with the diamond to generate Al4C3 and Cu-Al-C in situ, significantly improving the interfacial bonding strength of the diamond and the copper matrix. After sintering is completed, the sintered body is naturally cooled to room temperature to obtain a diamond-copper mixed powder.

[0043] 3) Internal oxidation-reduction-sintering: the diamond-copper mixed powder obtained in step 2) and cuprous oxide particles (Cu2O) are mixed. The amount of cuprous oxide added is 1.2:1 in terms of the molar ratio of oxygen elements to Al elements in the copper-aluminum alloy powder in step 1). Then 3 wt% of phenolic resin based on the total mass of the raw materials (diamond-copper mixed powder and cuprous oxide particles) is added to enhance the pressing forming ability. After mixing, the green body is cold isostatic pressed under a pressure of 200 MPa, and the green body density is controlled to be 5.2 g / cm 3 .

[0044] The green body is loaded into the furnace, nitrogen is introduced to remove air, the nitrogen pressure is maintained at 3 atm, and the temperature is raised to 850℃ for internal oxidation for 2h. At this time, the remaining aluminum elements and oxygen elements in the cuprous oxide are internally oxidized to generate Al2O3 nanoparticles in situ, which not only fills the interfacial gap but also serves as a thermal conduction path, improving the thermal conductivity of the composite material and effectively inhibiting crack propagation, thereby improving the mechanical properties.

[0045] After internal oxidation, hydrogen is introduced to remove nitrogen, the hydrogen pressure is maintained at 3 atm, and reduction is carried out at 880℃ for 2h. At this time, the unreacted cuprous oxide is reduced to elemental copper. During the reduction process, an exhaust port is opened at the bottom of the furnace, and hydrogen is ignited.

[0046] After reduction, the temperature is further raised to 900℃ for sintering for 2h. After sintering is completed, the sintered body is cooled to 200-300℃, and then the hydrogen is turned off to obtain a high-strength and high-thermal-conductivity copper-based composite material.

[0047] The high-strength and high-thermal-conductivity copper-based composite material prepared in this embodiment is the high-strength and high-thermal-conductivity copper-based composite material provided by the present application. The following examples are the same, and will not be repeated hereinafter.

[0048] Example 2 The preparation method of the high-strength high-thermal-conductivity copper-based composite material of the present embodiment is as follows: 1) Raw material mixing: diamond particles with a particle size of 50-200 μm are washed with concentrated sulfuric acid and hydrogen peroxide to remove surface impurities, and then the acid-washed diamond particles and 20-80 μm Cu-Al alloy powder (Al content 2 wt%) are ball-mixed at a volume ratio of 60:40 for 60 min to obtain a mixed powder.

[0049] 2) Interface reaction heat treatment: the mixed powder obtained in step 1) is placed in a sintering furnace and heated to 700℃ under an argon atmosphere (purity ≥ 99.999%) for 60 min. At this time, the aluminum in the copper-aluminum alloy powder is partially dissolved and reacts with the diamond to generate Al4C3 and Cu-Al-C in situ, significantly improving the interface bonding strength of the diamond and the copper matrix. After sintering is completed, the sintered body is naturally cooled to room temperature to obtain a diamond-copper mixed powder.

[0050] 3) Internal oxidation-reduction-sintering: the diamond-copper mixed powder obtained in step 2) and cuprous oxide particles (Cu2O) are mixed. The amount of cuprous oxide added is 1.2:1 in terms of the molar ratio of oxygen elements to Al elements in the copper-aluminum alloy powder in step 1). Then, 2 wt% of polyvinyl alcohol (PVA) based on the total mass of the raw materials (diamond-copper mixed powder and cuprous oxide particles) is added to enhance the pressing forming ability (cost lower than that of phenolic resin). After mixing, the green body is cold isostatic pressed under a pressure of 200 MPa, and the green body density is controlled to be 4.8 g / cm 3 .

[0051] The green body is loaded into the furnace, nitrogen is introduced to remove air, the nitrogen pressure is maintained at 3 atm, and the temperature is raised to 920℃ for internal oxidation for 6 h. At this time, the remaining aluminum elements and oxygen elements in the cuprous oxide are internally oxidized to generate Al2O3 nanoparticles in situ, which not only fill the interfacial gaps but also serve as thermal conduction paths to improve the thermal conductivity of the composite material. In addition, due to the high Al content in the Cu-Al alloy powder, the generated Al2O3 nanoparticles have high content and uniform distribution, which can significantly improve the thermal fatigue resistance of the material.

[0052] After internal oxidation, hydrogen is introduced to remove nitrogen, the hydrogen pressure is maintained at 3 atm, and reduction is carried out at 900℃ for 6 h. At this time, the unreacted cuprous oxide is reduced to elemental copper. During the reduction process, an exhaust port is opened at the bottom of the furnace, and hydrogen is ignited.

[0053] After reduction, the temperature is further raised to 950℃ for sintering for 6 h. After sintering is completed, the sintered body is cooled to 200-300℃, and then the hydrogen is turned off to obtain a high-strength high-thermal-conductivity copper-based composite material.

[0054] Example 3 The preparation method of the high-strength and high-thermal-conductivity copper-based composite material of the present embodiment is as follows: 1) Raw material mixing: diamond particles with a particle size < 50 μm and Cu-Al alloy powder (Al content 2 wt%) with a particle size of 5-20 μm are ball-mixed at a volume ratio of 70:30 for 120 min to obtain a mixed powder.

[0055] 2) Interface reaction heat treatment: the mixed powder obtained in step 1) is placed in a sintering furnace and heated to 700℃ under an argon atmosphere (purity ≥ 99.999%) for 60 min. At this time, the aluminum in the copper-aluminum alloy powder is partially dissolved and reacts with the diamond to generate Al4C3 and Cu-Al-C in situ, significantly improving the interface bonding strength between the diamond and the copper matrix. After sintering is completed, the sintered body is naturally cooled to room temperature to obtain a diamond-copper mixed powder.

[0056] 3) Internal oxidation-reduction-sintering: the diamond-copper mixed powder obtained in step 2) and cuprous oxide particles (Cu2O) are mixed. The amount of cuprous oxide added is 1.2:1 in terms of the molar ratio of oxygen elements to Al elements in the copper-aluminum alloy powder in step 1). Then, 3 wt% of phenolic resin based on the total mass of the raw materials (diamond-copper mixed powder and cuprous oxide particles) is added. After mixing, the green body is cold isostatic pressed under a pressure of 200 MPa to form a compact. The density of the compact is controlled to be 5.0 g / cm 3 .

[0057] The compact is loaded into a furnace tube, nitrogen is introduced to replace the air, the nitrogen pressure is maintained at 3 atm, and the temperature is raised to 920℃ for internal oxidation for 4 h. At this time, the remaining aluminum elements and oxygen elements in the cuprous oxide are internally oxidized to generate Al2O3 nanoparticles in situ, which not only fill the interface gaps but also serve as thermal conduction paths to improve the thermal conductivity of the composite material.

[0058] After internal oxidation is completed, hydrogen is introduced to replace the nitrogen, the hydrogen pressure is maintained at 3 atm, and reduction is carried out at 910℃ for 4 h. At this time, the unreacted cuprous oxide is reduced to elemental copper. During the reduction process, an exhaust port is opened at the bottom of the furnace body and hydrogen is ignited.

[0059] After reduction is completed, the temperature is further raised to 930℃ for sintering for 4 h. After sintering is completed, the sintered compact is cooled to 200-300℃ with the furnace, and then the hydrogen is turned off to obtain a high-strength and high-thermal-conductivity copper-based composite material.

[0060] Example 4 The preparation method of the high-strength and high-thermal-conductivity copper-based composite material of the present embodiment is as follows: 1) Raw material mixing: Diamond particles with particle size <50 μm are coated with an Al coating using magnetron sputtering on the surface, the thickness of the Al coating is 1 μm, then the diamond particles with the Al coating and Cu-Al alloy powder (Al content 2 wt%) of 5-20 μm are ball-mixed at a volume ratio of 70:30 for 120 min to obtain a mixed powder.

[0061] 2) Interface reaction heat treatment: The mixed powder obtained in step 1) is placed in a sintering furnace, heated to 700℃ under an argon atmosphere (purity ≥99.999%), and kept for 60 min, at which time the aluminum in the copper-aluminum alloy powder is partially dissolved and reacts with the diamond to generate Al4C3 and a Cu-Al-C mixture in situ, significantly improving the interface bonding strength of the diamond and the copper matrix; after sintering is completed, it is naturally cooled to room temperature to obtain a diamond-copper mixed powder.

[0062] 3) Internal oxidation-reduction-sintering: The diamond-copper mixed powder obtained in step 2) and cuprous oxide particles (Cu2O) are mixed, the amount of cuprous oxide added is according to the molar ratio of oxygen element to Al element in the copper-aluminum alloy powder in step 1) is 1.2:1, then 3wt% of phenolic resin based on the total mass of the raw materials (diamond-copper mixed powder and cuprous oxide particles) is added, and after mixing, the green body is pressed into a compact body by cold isostatic pressing under a pressure of 200Mpa, and the density of the green body is controlled to be 5.0g / cm 3 .

[0063] The compact body is loaded into the furnace, nitrogen is introduced to exhaust the air, the nitrogen pressure is maintained at 3atm, and the temperature is raised to 920℃ for internal oxidation for 4h, at which time the remaining aluminum element and the oxygen element in the cuprous oxide are internally oxidized to generate Al2O3 nanoparticles, which not only fill the interface gap, but also serve as a thermal conduction path to improve the thermal conductivity of the composite material.

[0064] After internal oxidation is completed, hydrogen is introduced to exhaust the nitrogen, the hydrogen pressure is maintained at 3atm, and reduction is carried out at 910℃ for 4h, at which time the unreacted cuprous oxide is reduced to elemental copper, and during the reduction process, an exhaust port is opened at the bottom of the furnace and hydrogen is ignited.

[0065] After reduction is completed, continue to heat to 930℃ for sintering for 4h, after sintering is completed, the sintered compact is cooled to 200-300℃, then the hydrogen is turned off, and a high-strength high-thermal-conductivity copper-based composite material is obtained.

[0066] Example 5 The preparation method of the high-strength high-thermal-conductivity copper-based composite material of the present embodiment is as follows: 1) Raw material mixing: diamond particles with particle size <50 μm were coated with an Al coating using magnetron sputtering on the surface, the thickness of the Al coating was 1 μm, then the diamond particles with the Al coating and Cu-Al alloy powder (Al content 2 wt%) of 5-20 μm were ball-mixed at a volume ratio of 50:50 for 120 min to obtain a mixed powder.

[0067] 2) Interface reaction heat treatment: the mixed powder obtained in step 1) was placed in a sintering furnace and heated to 700℃ under an argon atmosphere (purity ≥99.999%), and kept for 60 min, at this time, the aluminum in the copper-aluminum alloy powder was partially dissolved and reacted with the diamond to generate Al4C3 and Cu-Al-C in situ, significantly improving the interface bonding strength of the diamond and the copper matrix; after sintering, it was naturally cooled to room temperature to obtain a diamond-copper mixed powder.

[0068] 3) Internal oxidation-reduction-sintering: the diamond-copper mixed powder obtained in step 2) and cuprous oxide particles (Cu2O) were mixed, the amount of cuprous oxide added was according to the molar ratio of oxygen element to Al element in the copper-aluminum alloy powder in step 1) was 1.2:1, then 3wt% of phenolic resin based on the total mass of the raw materials (diamond-copper mixed powder and cuprous oxide particles) was added, and then mixed and cold isostatic pressed into a green body under a pressure of 200Mpa, the green body density was controlled to be 5.0g / cm 3 .

[0069] The green body was loaded into the furnace, nitrogen was introduced to exhaust the air, the nitrogen pressure was maintained at 3atm, and the temperature was raised to 920℃ for internal oxidation for 4h, at this time, the remaining aluminum element and the oxygen element in the cuprous oxide were in-situ internal oxidized to generate Al2O3 nanoparticles, which not only filled the interface gap, but also served as a thermal conduction path to improve the thermal conductivity of the composite material.

[0070] After internal oxidation, hydrogen was introduced to exhaust the nitrogen, the hydrogen pressure was maintained at 3atm, and reduction was carried out at 910℃ for 4h, at this time, the unreacted cuprous oxide was reduced to elemental copper, and during the reduction process, an exhaust port was opened at the bottom of the furnace and the hydrogen was ignited.

[0071] After reduction, the temperature was continuously raised to 930℃ for sintering for 4h, after sintering, the sintered body was cooled to 200-300℃ with the furnace, then the hydrogen was turned off, and a high-strength high-thermal-conductivity copper-based composite material was obtained.

[0072] Example 2 Example 1 The preparation method of the copper-based composite material of this example is as follows: 1) raw material mixing forming: the diamond particles with a particle size of <50 μm, Cu-Al alloy powder (Al content 2wt%) of 5~20 μm, cuprous oxide particles (Cu2O) are mixed, and 3wt% of phenolic resin is added for enhancing the pressing forming ability, and after mixing, the green body is cold isostatic pressed, and the green body density is controlled to be 5.0g / cm 3 . Among them, Cu2O is dosed according to the molar ratio of oxygen element to Al element in the Cu-Al alloy powder is 1.2:1, and the diamond and Cu-Al alloy powder are in a volume ratio of 70:30.

[0073] 2) internal oxidation-reduction-sintering: the green body obtained in step 1) is loaded into a furnace, nitrogen is introduced to exhaust air, the nitrogen pressure is maintained at 3atm, and the temperature is raised to 920℃ for internal oxidation for 4h. After internal oxidation, hydrogen is introduced to exhaust nitrogen, and the hydrogen pressure is maintained at 3atm, and the reduction is carried out at 910℃ for 4h. During the reduction process, an exhaust port is opened at the bottom of the furnace body and the hydrogen is ignited.

[0074] After reduction, continue to heat to 930℃ for sintering for 4h, and after sintering, the sintered body is cooled to 200~300℃, then the hydrogen is turned off, and a copper-based composite material is obtained.

[0075] Three, experimental example The copper-based composite materials obtained in the examples and comparative examples are tested for performance, the bending strength is tested according to GB / T 232-2024 "Metallic Materials Bending Test Method", and the thermal conductivity is tested according to GB / T22588-2008 "Flash Method for Measuring Thermal Diffusivity or Thermal Conductivity", and the test results are shown in Table 1.

[0076] Table 1 Performance test results of copper-based composite materials

[0077] The increase of the volume fraction of diamond is crucial to the improvement of the thermal conductivity of the composite material, the copper-based composite material prepared by the present application can ensure that the volume fraction of diamond reaches more than 50%, and the Al2O3 nanoparticles in the copper-based composite material prepared by the present application can further improve the thermal conductivity as a thermal conduction path, and the thermal conductivity reaches more than 620 W / m•K; at the same time, the Al4C3 layer and Cu-Al-C mixture generated in situ on the surface of the diamond can improve the interface bonding ability, and further improve the mechanical properties, and the bending strength reaches 350MPa, and a high-strength and high-thermal-conductivity copper-based composite material is obtained.

[0078] The copper-based composite material obtained by the present application does not need high-cost diamond particle size gradient distribution technology, and the thermal conductivity is close to the thermal conductivity (800~1000W / m•K) of the high-end diamond / copper composite material product of Element Six company.

[0079] In addition, compared with Example 1, as the aluminum content increases (Examples 2-3), the content of generated Al2O3 nanoparticles is further increased, thereby improving the bending strength of the material. And compared with Example 3, Example 4 pre-coats an Al layer on the surface of the diamond, which can further improve the bending performance and thermal conductivity.

[0080] Compared with Example 3, the inner oxidation-reduction-sintering of Comparative Example 1 is carried out by directly mixing, which can greatly reduce the bending performance and thermal conductivity.

[0081] The preparation method of the copper-based composite material provided by the application can flexibly match the requirements of different application scenarios (such as high thermal conductivity and high bending strength) by adjusting the Al content, the volume fraction of the diamond, and the sintering parameters; and without additional plating of a transition layer or complex equipment, the application is suitable for existing powder metallurgy production lines, the process is simplified, and the cost is reduced by more than 30%.

[0082] Finally, it should be noted that: the above only describes the preferred embodiments of the application and is not used to limit the application, although the application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or make equivalent replacement for some technical features, any modification, equivalent replacement, improvement, etc. within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A method for preparing a high-strength and high-thermal-conductivity copper-based composite material, characterized in that: The following steps are involved: 1) Diamond particles and copper-aluminum alloy powder are mixed and heat treated at 700-900°C in an inert atmosphere to obtain diamond-copper mixed powder; 2) The diamond-copper mixed powder obtained in step 1) is mixed with an oxygen source and then pressed into a shape, and subjected to internal redox sintering.

2. The method for preparing the high-strength and high-thermal-conductivity copper-based composite material according to claim 1, wherein: The volume ratio of the diamond particles to the copper-aluminum alloy powder in step 1) is (50-70): (50-30), and the aluminum content in the copper-aluminum alloy powder is ≥1 wt%.

3. The method for preparing the high-strength and high-thermal-conductivity copper-based composite material according to claim 1, wherein: The aluminum content in the copper-aluminum alloy powder is 1~2wt%.

4. The method for preparing the high-strength and high-thermal-conductivity copper-based composite material according to claim 1, wherein: The heat treatment temperature in step 1) is 700-750° C., and the heat treatment time is 1-4 hours.

5. The method for preparing the high-strength and high-thermal-conductivity copper-based composite material according to claim 1, wherein: The heat treatment time is 1~1.2h.

6. The method for preparing the high-strength and high-thermal-conductivity copper-based composite material according to claim 1, wherein: The molar ratio of the oxygen element in the oxygen source in step 2) to the aluminum element in the copper-aluminum alloy powder in step 1) is (1.2-1.5):

1.

7. The method for preparing the high-strength and high-thermal-conductivity copper-based composite material according to claim 1, wherein: The surface of the diamond particles in step 1) is coated with an aluminum layer, and the thickness of the aluminum layer is 1-1.5 μm.

8. The method for preparing the high-strength and high-thermal-conductivity copper-based composite material according to any one of claims 1 to 6, characterized in that: In step 2), the internal oxidation temperature is 850-950° C., and the internal oxidation time is 2-6 hours; the reduction temperature is 880-980° C., and the reduction time is 2-6 hours; the sintering temperature is 900-960° C., and the sintering time is 2-6 hours.

9. The method for preparing the high-strength and high-thermal-conductivity copper-based composite material according to claim 1, wherein: The oxygen source in step 2) is cuprous oxide.

10. A high-strength and high-thermal-conductivity copper-based composite material obtained by the method for preparing the high-strength and high-thermal-conductivity copper-based composite material according to any one of claims 1 to 9.

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