Surface porous diamond copper composite material and preparation method thereof

Abstract

The invention discloses a preparation method of a surface porous diamond copper composite material, and the surface porous diamond copper composite material is prepared by performing plasma cleaning, metallization treatment, copper plating, pressing and sintering on surface porous diamond powder. According to the preparation method of the diamond copper composite material with the porous surface, the heat conduction mode can be optimized through metallization, the heat conduction efficiency is improved, the problem of non-uniformity caused by a traditional powder mixing mode can be solved through copper electroplating after metallization, the material consistency is improved, the surface state of a sandwich structure is good, and the direct-current hot pressing sintering method is short in time, high in efficiency and low in energy consumption; compared with an existing preparation technology, the impact resistance of the finished material is improved, and the method is easy and convenient to implement and can be widely applied to production.

Description

Technical Field

[0001] This invention belongs to the field of copper-based composite material technology, and relates to a porous diamond copper composite material, as well as a method for preparing the porous diamond copper composite material. Background Technology

[0002] With the increasing power levels of highly integrated devices, higher demands are being placed on the performance of thermal management materials. The heat dissipation problem in electronic devices is becoming increasingly severe, and various fields urgently need a new generation of thermal management solutions that can meet the requirements of efficient heat dissipation. Diamond, with its high thermal conductivity (1800-2000 W / m·K) and low coefficient of thermal expansion (0.8 × 10⁻⁶ W / m·K), is a suitable material for heat dissipation. -6 / K), lightweight (3.52g / cm³) 3 Its advantages make it the preferred choice for enhancers.

[0003] Diamond particle-reinforced metal matrix composites have become a research hotspot for next-generation high-performance electronic packaging materials due to their high thermal conductivity, low coefficient of thermal expansion, high elastic modulus, and good wear resistance. Among common metals, copper has the second highest thermal conductivity after silver, while also possessing advantages such as high machinability and easy availability, making it an excellent metal matrix. The core structure of diamond-copper composites consists of diamond particles as the reinforcing phase forming the framework, and a copper matrix as the continuous phase filling its pores. Through interface treatment optimization, the two are combined to ultimately form a composite structure that combines the high hardness and high thermal conductivity of diamond with the high electrical conductivity and good machinability of copper. This structural design gives it irreplaceable advantages in aerospace, electronic heat dissipation, and other fields. Currently, diamond / copper matrix composites have become one of the main directions in the research and development of next-generation thermal management materials, with broad development prospects in cutting-edge fields such as aerospace, military technology, and rail transportation, as well as civilian fields such as mobile devices and communication base stations. Under current conditions, researchers have solved the problem of low thermal conductivity through surface modification and metallization methods, but significant challenges remain regarding the coefficient of thermal expansion, density, and thermal shock resistance.

[0004] Existing diamond / copper composite materials have a significant drawback: their thermal conductivity decreases sharply with increasing thermal shock cycles during both hot and cold use, resulting in poor thermal shock resistance—an unacceptable limitation for their applications. Our company's experimental data shows that after 800 thermal shock cycles, the thermal conductivity of conventional diamond-copper composite materials decreased from 583 W / mK to 507 W / mK, a reduction of 13.0%. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a porous diamond-copper composite material, which solves the problem of poor thermal shock resistance of diamond-copper composite materials in the prior art.

[0006] Another object of the present invention is to provide a porous diamond-copper composite material.

[0007] The technical solution adopted in this invention is a method for preparing a porous diamond-copper composite material, specifically including the following steps: Step 1: Perform plasma cleaning on the porous diamond powder on the surface; Step 2: Coat the diamond surface with a strong carbon metal; Step 3: Plate a copper layer on the surface of the strong carbon metal; Step 4: Perform heat treatment to obtain diamond copper-based composite material powder; Step 5: Press the powder into a pre-coated copper sheet to obtain a copper-coated preform. Step 6: Place the graphite pressure column and copper-clad preform into the mold in sequence and assemble them into a component; Step 7: Heat and sinter the components; Step 8: Remove excess parts and oxide film generated during sintering from the component to obtain porous diamond copper composite material.

[0008] The technical solution of this invention is also characterized by: The specific operation of step 1 is as follows: place the porous diamond powder in the vacuum chamber of the plasma cleaner, and then use argon gas to generate high-energy plasma through DC power supply to bombard the surface of the porous diamond. At the same time, the ultrasonic vibration platform is used to make each surface of the diamond roll evenly to complete the plasma cleaning of each surface. The particle size of the porous diamond powder on the surface is 5μm~150μm; During the ignition process, the power supply voltage is 1800V~2200V, and the bias voltage is 350V~450V; the plasma cleaning time is 40min~60min.

[0009] The specific operation of step 2 is as follows: use a physical magnetron sputtering coating machine to metallize the porous diamond surface with strong carbon metal, which can be any one of Cr, Zr, W, or Mo; the particle size of the strong carbon metal powder is 0.8μm~5μm; The specific parameters are: coating power of 1200W~1500W, coating time of 10min~30min, and coating thickness of 100nm~300nm.

[0010] The specific steps for step 3 are as follows: Step 3-1: Pre-plat a copper layer on the surface of a strong carbon metal; Pure copper is deposited in a physical magnetron sputtering coating machine. The diamond is uniformly rolled on each side by an ultrasonic vibration platform to complete the copper coating on each side. The specific parameters are: coating power 1200W~1500W, coating time 20min~30min, and coating thickness 100nm~200nm. Step 3-2: Perform a second copper plating; Copper plating is performed using a barrel plating machine; the barrel plating machine has a current of 7A~10A, a speed of 15r / min~30r / min, and a plating thickness of 5nm~50nm.

[0011] The heat treatment in step 4 is carried out in a high-vacuum reduction furnace with a vacuum level not exceeding 5 × 10⁻⁶. -3 Pa, sintering temperature 850℃~950℃, holding time 40min~60min.

[0012] Step 5 specifically consists of the following steps: Step 5-1: Press the powder obtained in step 4 to obtain a preform. The pressure is 60MPa~100MPa, the holding time is 20min~30min, and the density is pressed to more than 90%. The thickness of the pressed powder is 1mm~4mm and the diameter is 10mm~60mm. Step 5-2: Place pure copper sheets on the top and bottom of the preform, and press again to make the copper sheets stably cover the preform, thus obtaining a copper-clad preform; the thickness of the pure copper sheets is 0.05mm~2mm.

[0013] The mold sleeve in step 6 includes a graphite mold sleeve and a steel mold sleeve; The specific assembly operation is as follows: First, put the graphite mold sleeve into the steel mold sleeve, and then put the graphite pressure column, copper-clad preform, and graphite pressure column into the graphite mold sleeve in sequence. The thickness of the graphite pressure column is selected according to the actual needs. After the assembly is completed, the top surface of the upper graphite pressure column is higher than the height of the mold sleeve. The inner diameter of the mold sleeve is selected according to the diameter of the copper-clad preform. If multiple copper-clad preforms need to be sintered simultaneously, multiple copper-clad preforms are stacked between two graphite pillars, with graphite carbon paper separating each pair of copper-clad preforms; the thickness of the graphite carbon paper is 0.5mm~1mm.

[0014] The specific operation of heating and sintering in step 7 is as follows: use a hot pressing sintering machine to heat the component. The hot pressing sintering temperature is 900℃~1050℃, the holding time is 20min~40min, the heating rate is 6℃ / min~8℃ / min, the holding pressure is 40MPa~60MPa, and after the heat is stopped, the pressure is held for 60min~120min, and then the component is taken out after natural cooling to room temperature.

[0015] The specific operation of step 8 is as follows: remove the graphite mold sleeve, steel film sleeve and graphite pressure column from the component, then use a polishing machine to perform preliminary polishing on the copper oxide film generated after the copper sheet is sintered, and finally use dilute hydrochloric acid to remove the remaining copper oxide film on the surface.

[0016] Another technical solution adopted in this invention is a porous diamond-copper composite material, which is prepared by the above-mentioned method for preparing porous diamond-copper composite material. It consists of composite powder and a copper coating layer. The powder consists of porous diamond, a strong carbon metal layer and a copper layer from the inside to the outside. The density of the composite powder is not less than 96%. The particle size of the porous diamond powder is 5μm~150μm.

[0017] The beneficial effects of this invention are: The high specific surface area of ​​porous diamond-copper composite materials can increase interfacial bonding strength and improve thermal shock resistance. In the preparation method of the porous diamond-copper composite materials of this invention, metallization can optimize the heat conduction mode and improve the heat conduction efficiency. After metallization, copper electroplating can solve the unevenness problem caused by traditional powder mixing methods and improve material consistency. The "sandwich" structure has a good surface condition. The DC hot pressing sintering method is short, efficient, and energy-saving. Compared with existing preparation technologies, it improves the impact resistance of the finished material. Moreover, the method is simple to implement and can be widely used in production. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the assembly of components in step 6 of the preparation method of the porous diamond-copper composite material of the present invention; Figure 2 This is a state diagram of the porous diamond surface of the present invention.

[0019] In the diagram, 1. Graphite pressure column, 2. Pure copper sheet, 3. Copper-clad preform, 4. Graphite mold sleeve, 5. Steel mold sleeve, 6. Graphite carbon paper. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0021] This invention also provides a method for preparing the above-mentioned porous diamond-copper composite material, which is specifically implemented according to the following steps: Step 1: Perform plasma cleaning on the porous diamond powder on the surface; The specific operation is as follows: the porous diamond powder is placed in the vacuum chamber of the plasma cleaner, and then argon gas is used to generate high-energy plasma through DC power supply to bombard the surface of the porous diamond. At the same time, the ultrasonic vibration platform is used to make each surface of the diamond roll evenly to complete the plasma cleaning of each surface. The particle size of the surface porous diamond powder ranges from 5 μm to 150 μm; the state of the surface porous diamond is as follows: Figure 1 As shown; During the ignition process, the power supply voltage is 1800V~2200V and the bias voltage is 350V~450V; the plasma cleaning time is 40min~60min.

[0022] Step 2: Coat the diamond surface with a strong carbon metal; The porous diamond surface is metallized with a strong carbon metal using a physical magnetron sputtering coating machine. The strong carbon metal is any one of Cr, Zr, W, and Mo, and the particle size of the strong carbon metal powder is 0.8μm~5μm. The specific parameters are: coating power of 1200W~1500W, coating time of 10min~30min, and coating thickness of 100nm~300nm; The coating is produced by physical magnetron sputtering and ultrasonic vibration platform, resulting in uniform film and controllable thickness. The strong carbon metal is deposited by magnetron sputtering, and after heat treatment, the metal and diamond form a bond with high bonding strength, high thermal shock resistance, and low interfacial thermal resistance between diamond and the substrate.

[0023] Step 3: Plate a copper layer on the surface of the strong carbon metal; The specific steps are as follows: Step 3-1: Pre-plat a copper layer on the surface of a strong carbon metal; After metallization, pure copper is deposited in a physical magnetron sputtering coating machine. The diamond is uniformly rolled on each side by an ultrasonic vibration platform to complete the copper plating on each side. The specific parameters are: coating power 1200W~1500W, coating time 20min~30min, and coating thickness 100nm~200nm. Using magnetron sputtering for copper plating allows for direct follow-up electroplating, eliminating the problem of introducing impurities such as nickel and salts that affect thermal conductivity when electroplating is performed after chemical nickel or copper plating in traditional techniques.

[0024] Step 3-2: Perform a second copper plating; Using a barrel plating machine for copper plating, the copper plating solution includes copper sulfate, sulfuric acid, sodium chloride and polyethylene glycol, which eliminates the problem of uneven mixing caused by the different densities of diamond and copper powder in traditional mixing technology, while ensuring full wetting of the porous diamond on the surface and increasing the bonding force at the interface. The concentration of copper sulfate is 158 g / L; the concentration of sulfuric acid is 45 g / L; the concentration of sodium chloride is 0.1 g / L; the concentration of polyethylene glycol is 0.05 g / L, and the molecular weight is 2000. The barrel plating machine has a current of 7A~10A, a rotation speed of 15r / min~30r / min, and a plating thickness of 5nm~50nm.

[0025] Step 4: Perform heat treatment to obtain diamond copper-based composite material powder; The heat treatment is carried out in a high-vacuum reduction furnace with a vacuum level not exceeding 5 × 10⁻⁶. -3 Pa, sintering temperature 850℃~950℃, holding time 40min~60min; Step 5: Press the powder-coated pure copper sheet 2 to obtain the copper-coated preform 3; The specific steps are as follows: Step 5-1: Press the powder obtained in step 4 to obtain a preform. The pressure is 60MPa~100MPa, the holding time is 20min~30min, and the powder is pressed repeatedly until the density reaches more than 90%. The thickness of the pressed powder is 1mm~4mm and the diameter is 10mm~60mm. Step 5-2: Place pure copper sheet 2 on the top and bottom of the preform, and press it again to make the copper sheet stably cover the preform, to obtain copper-clad preform 3; the thickness of pure copper sheet 2 is 0.05mm~2mm.

[0026] Step 6: Place the graphite pressure column 1 and the copper-clad preform 3 into the mold in sequence and assemble them into a component; like Figure 1 The structure shown includes a graphite mold sleeve 4 and a steel mold sleeve 5. The specific assembly operation is as follows: first, the graphite mold sleeve 4 is placed into the steel mold sleeve 5, and then the graphite pressure column 1, the copper-clad preform 3, and the graphite pressure column 1 are placed into the graphite mold sleeve 4 in sequence. The thickness of the graphite pressure column 1 is selected according to the actual needs. After assembly, the top surface of the upper graphite pressure column 1 is higher than the height of the mold sleeve. The inner diameter of the mold sleeve is selected according to the diameter of the copper-clad preform. If multiple copper-clad preforms 3 need to be sintered simultaneously, multiple copper-clad preforms are stacked between two layers of graphite pressure columns 1, and graphite carbon paper 6 is used to separate each two layers of copper-clad preforms; the thickness of graphite carbon paper 6 is 0.5mm~1mm.

[0027] Step 7: Heat and sinter the components; The specific operation of heating and sintering is as follows: the assembled components are heated on a hot press sintering machine. The specific process parameters are: hot press sintering temperature 900℃~1050℃, holding time 20min~40min, heating rate 6℃ / min~8℃ / min, holding pressure 40MPa~60MPa, holding pressure for 60min~120min after heating is stopped, and then naturally cooled to room temperature and taken out. The copper-based composite material is sintered using a hot-press sintering machine for direct heating, resulting in fast heating speed and high efficiency.

[0028] Step 8: Remove excess parts and oxide film generated during sintering from the component to obtain porous diamond copper composite material.

[0029] Remove the graphite mold sleeve 4, steel film sleeve 5 and graphite pressure column 1 from the component, and then use a polishing machine to perform preliminary polishing on the copper oxide film generated after the copper sheet is sintered. Polish until the roughness required for actual production is achieved, and finally use 1:1 dilute hydrochloric acid to remove the remaining copper oxide film on the surface, thus obtaining a porous diamond copper composite material.

[0030] The present invention also provides a porous diamond-copper composite material, which is prepared according to the above-mentioned method for preparing porous diamond-copper composite material. It consists of composite powder and a copper coating layer. The powder consists of porous diamond, a strong carbon metal layer and a copper layer from the inside to the outside. The density of the composite powder is not less than 96%. The particle size of the porous diamond powder is 5μm to 150μm.

[0031] The porous diamond-copper composite material provided by this invention uses porous diamond. After processing, the diamond surface changes from smooth to full of holes, increasing the specific surface area and the interfacial contact area, thereby improving the interfacial bonding strength and thermal shock resistance. Its thermal conductivity is not less than 600 W / mK, and its thermal expansion coefficient is 5 ppm / ℃ to 10 ppm / ℃. After 800 cycles of thermal shock at 200℃, the thermal conductivity decreases by no more than 5%.

[0032] Example 1 The preparation method of the porous diamond-copper composite material in this embodiment is specifically implemented according to the following steps: Step 1: Perform plasma cleaning on the porous diamond powder on the surface; The porous diamond is placed in the vacuum chamber of a plasma cleaner. Argon gas is used to generate high-energy plasma through a DC power supply to bombard the surface of the foam diamond. The plasma cleaning of each side of the diamond is achieved by rotating the built-in roller. The surface porous diamond particles have a size of 40μm~50μm, the cleaning time is 40min, the ion source voltage is 1800v, ​​and the bias voltage is 350v. Step 2: Coat the diamond surface with a strong carbon metal; The porous diamond surface was metallized by depositing Cr carbide metal in a physical magnetron sputtering coating machine. The specific parameters were: coating power 1200W, coating time 10min, and coating thickness 150nm. Step 3: Plate a copper layer on the surface of the strong carbon metal; Cu was deposited in a physical magnetron sputtering coating machine with the following parameters: coating power 1200W, coating time 20min, and coating thickness 100nm. The copper plating process is then carried out in a barrel plating machine with a current of 7A, a rotation speed of 15r / min, and a plating thickness of 20nm. Step 4: Perform heat treatment to obtain diamond copper-based composite material powder; The heat treatment was carried out in a high vacuum reduction furnace with a vacuum degree not exceeding 5×10-3 Pa, a sintering temperature of 850℃, and a holding time of 50 min. Step 5: Press the powder-coated pure copper sheet 2 to obtain the copper-coated preform 3; The specific steps are as follows: Step 5-1: Press the powder obtained in step 4 to obtain a preform. The pressure is 80 MPa, the holding time is 20 min, and the powder is repeatedly pressed up and down until the density reaches 90%. The thickness of the pressed powder is 1 mm and the diameter is 50 mm. Step 5-2: Place pure copper sheet 2 on the top and bottom of the preform, apply pressure of 10MPa, hold pressure for 30s, and press again to make the copper sheet stably cover the preform, thus obtaining copper-clad preform 3; the thickness of pure copper sheet 2 is 0.05mm. Step 6: Place the graphite pressure column 1 and the copper-clad preform 3 into the mold in sequence and assemble them into a component; Step 7: Heat and sinter the components; The sample was heated on a hot pressing sintering machine with the following specific process parameters: hot pressing sintering temperature 900°C, holding time 20 min, heating rate 6°C / min, holding pressure 50 MPa, holding pressure for 60 min after heating was stopped, and then naturally cooled to room temperature before the sample was taken out. Step 8: Remove excess parts and oxide film generated during sintering from the component to obtain porous diamond copper composite material; The copper layer on the surface is removed by using a polishing machine, and the copper oxide film on the surface is removed by using 1:1 dilute hydrochloric acid, thus obtaining the porous diamond copper composite material of this embodiment.

[0033] The porous diamond-copper composite material prepared in this embodiment was tested and found to have a thermal conductivity of 612 W / (mK), a coefficient of thermal expansion of 5.34 ppm / ℃, and a density of 5.3 g / cm³. 3 After 800 cycles of thermal shock at 200°C, the thermal conductivity decreased to 4.8%.

[0034] Example 2 The preparation method of the porous diamond-copper composite material in this embodiment is specifically implemented according to the following steps: Step 1: Perform plasma cleaning on the porous diamond powder on the surface; The porous diamond is placed in the vacuum chamber of a plasma cleaner. Argon gas is used to generate high-energy plasma through a DC power supply to bombard the surface of the foam diamond. The plasma cleaning of each side of the diamond is achieved by rotating the built-in roller. The surface porous diamond particles have a size of 40μm~50μm, the cleaning time is 40min, the ion source voltage is 2000v, and the bias voltage is 350v. Step 2: Coat the diamond surface with a strong carbon metal; The porous diamond surface was metallized by depositing Cr carbide metal in a physical magnetron sputtering coating machine. The specific parameters were: coating power 1200W, coating time 20min, and coating thickness 260nm. Step 3: Plate a copper layer on the surface of the strong carbon metal; Cu was deposited in a physical magnetron sputtering coating machine with the following parameters: coating power 1400W, coating time 20min, and coating thickness 180nm. The copper plating process is then carried out in a barrel plating machine with a current of 7A, a rotation speed of 15r / min, and a plating thickness of 40nm. Step 4: Perform heat treatment to obtain diamond copper-based composite material powder; The heat treatment was carried out in a high vacuum reduction furnace with a vacuum degree not exceeding 5×10-3 Pa, a sintering temperature of 850℃, and a holding time of 50 min. Step 5: Press the powder-coated pure copper sheet 2 to obtain the copper-coated preform 3; The specific steps are as follows: Step 5-1: Press the powder obtained in step 4 to obtain a preform. The pressure is 80 MPa and the holding time is 20 min. Press repeatedly from top to bottom until the density reaches 90%. The pressing thickness is 2 mm and the diameter is 50 mm. Step 5-2: Place pure copper sheet 2 on the top and bottom of the preform, apply pressure of 10MPa, hold pressure for 30s, and press again to make the copper sheet stably cover the preform, thus obtaining copper-clad preform 3; the thickness of pure copper sheet 2 is 0.8mm. Step 6: Place the graphite pressure column 1 and the copper-clad preform 3 into the mold in sequence and assemble them into a component; Step 7: Heat and sinter the components; The sample was heated on a hot pressing sintering machine with the following specific process parameters: hot pressing sintering temperature 900°C, holding time 20 min, heating rate 8°C / min, holding pressure 50 MPa, holding pressure for 60 min after heating was stopped, and then naturally cooled to room temperature before the sample was taken out. Step 8: Remove excess parts and oxide film generated during sintering from the component to obtain porous diamond copper composite material; The copper layer on the surface is removed by using a polishing machine, and the copper oxide film on the surface is removed by using 1:1 dilute hydrochloric acid, thus obtaining the porous diamond copper composite material of this embodiment.

[0035] The porous diamond-copper composite material prepared in this embodiment was tested and found to have a thermal conductivity of 625 W / (mK), a coefficient of thermal expansion of 5.47 ppm / ℃, and a density of 5.49 g / cm³. 3 After 800 cycles of thermal shock at 200°C, the thermal conductivity decreased to 4.7%.

[0036] Example 3 The preparation method of the porous diamond-copper composite material in this embodiment is specifically implemented according to the following steps: Step 1: Perform plasma cleaning on the porous diamond powder on the surface; The porous diamond is placed in the vacuum chamber of a plasma cleaner. Argon gas is used to generate high-energy plasma through a DC power supply to bombard the surface of the foam diamond. The plasma cleaning of each side of the diamond is achieved by rotating the built-in roller. The surface porous diamond particles have a size of 50μm~60μm, the cleaning time is 60min, the ion source voltage is 2200v, and the bias voltage is 400v. Step 2: Coat the diamond surface with a strong carbon metal; The porous diamond surface was metallized by depositing Cr carbide metal in a physical magnetron sputtering coating machine. The specific parameters were: coating power 1200W, coating time 20min, and coating thickness 300nm. Step 3: Plate a copper layer on the surface of the strong carbon metal; Cu was deposited in a physical magnetron sputtering coating machine with the following parameters: coating power 1400W, coating time 20min, and coating thickness 200nm. The copper plating process is then carried out in a barrel plating machine with a current of 7A, a rotation speed of 15r / min, and a plating thickness of 50nm. Step 4: Perform heat treatment to obtain diamond copper-based composite material powder; The heat treatment was carried out in a high vacuum reduction furnace with a vacuum degree not exceeding 5×10-3 Pa, a sintering temperature of 900℃, and a holding time of 50 min. Step 5: Press the powder-coated pure copper sheet 2 to obtain the copper-coated preform 3; The specific steps are as follows: Step 5-1: Press the powder obtained in step 4 to obtain a preform. The pressure is 100MPa and the holding time is 20min. Press repeatedly up and down until the density reaches more than 90%. The pressing thickness is 4mm and the diameter is 60mm. Step 5-2: Place pure copper sheet 2 on the top and bottom of the preform, apply pressure of 10MPa, hold pressure for 30s, and press again to make the copper sheet stably cover the preform, to obtain copper-clad preform 3; the thickness of pure copper sheet 2 is 1mm. Step 6: Place the graphite pressure column 1 and the copper-clad preform 3 into the mold in sequence and assemble them into a component; Step 7: Heat and sinter the components; The sample was heated on a hot pressing sintering machine with the following specific process parameters: hot pressing sintering temperature 900°C, holding time 20 min, heating rate 8°C / min, holding pressure 50 MPa, holding pressure for 80 min after heating was stopped, and then naturally cooled to room temperature before the sample was taken out. Step 8: Remove excess parts and oxide film generated during sintering from the component to obtain porous diamond copper composite material; The copper layer on the surface is removed by using a polishing machine, and the copper oxide film on the surface is removed by using 1:1 dilute hydrochloric acid, thus obtaining the porous diamond copper composite material of this embodiment.

[0037] The porous diamond-copper composite material prepared in this embodiment was tested and found to have a thermal conductivity of 667 W / (mk), a coefficient of thermal expansion of 5.32 ppm / ℃, a density of 5.65 g / cm3, and a thermal conductivity that decreased to 4.45% after 800 cycles of thermal shock at 200℃.

[0038] Example 4 The preparation method of the porous diamond-copper composite material in this embodiment is implemented according to the following steps: Step 1: Perform plasma cleaning on the porous diamond powder on the surface; Step 2: Coat the diamond surface with a strong carbon metal; The specific operation of step 2 is as follows: use a physical magnetron sputtering coating machine to metallize the porous diamond surface with strong carbon metal, which can be any one of Cr, Zr, W, or Mo; the particle size of the strong carbon metal powder is 0.8μm~5μm; The specific parameters are: coating power of 1200W~1500W, coating time of 10min~30min, and coating thickness of 100nm~300nm; Step 3: Plate a copper layer on the surface of the strong carbon metal; Step 4: Perform heat treatment to obtain diamond copper-based composite material powder; Step 5: Press the powder-coated pure copper sheet 2 to obtain the copper-coated preform 3; Step 6: Place the graphite pressure column 1 and the copper-clad preform 3 into the mold in sequence and assemble them into a component; Step 7: Heat and sinter the components; Step 8: Remove excess parts and oxide film generated during sintering from the component to obtain porous diamond copper composite material.

[0039] Example 5 The preparation method of the porous diamond-copper composite material in this embodiment is implemented according to the following steps: Step 1: Perform plasma cleaning on the porous diamond powder on the surface; Step 2: Coat the diamond surface with a strong carbon metal; Step 3: Plate a copper layer on the surface of the strong carbon metal; The specific steps for step 3 are as follows: Step 3-1: Pre-plat a copper layer on the surface of a strong carbon metal; Pure copper is deposited in a physical magnetron sputtering coating machine. The diamond is uniformly rolled on each side by an ultrasonic vibration platform to complete the copper coating on each side. The specific parameters are: coating power 1200W~1500W, coating time 20min~30min, and coating thickness 100nm~200nm. Step 3-2: Perform a second copper plating; Copper plating is performed using a barrel plating machine; the barrel plating machine has a current of 7A~10A, a speed of 15r / min~30r / min, and a plating thickness of 5μm~50μm. Step 4: Perform heat treatment to obtain diamond copper-based composite material powder; Step 5: Press the powder-coated pure copper sheet 2 to obtain the copper-coated preform 3; Step 6: Place the graphite pressure column 1 and the copper-clad preform 3 into the mold in sequence and assemble them into a component; Step 7: Heat and sinter the components; Step 8: Remove excess parts and oxide film generated during sintering from the component to obtain porous diamond copper composite material.

[0040] Example 6 The preparation method of the porous diamond-copper composite material in this embodiment is implemented according to the following steps: Step 1: Perform plasma cleaning on the porous diamond powder on the surface; Step 2: Coat the diamond surface with a strong carbon metal; Step 3: Plate a copper layer on the surface of the strong carbon metal; Step 4: Perform heat treatment to obtain diamond copper-based composite material powder; Step 5: Press the powder-coated pure copper sheet 2 to obtain the copper-coated preform 3; Step 5 specifically consists of the following steps: Step 5-1: Press the powder obtained in step 4 to obtain a preform. The pressure is 60MPa~100MPa, the holding time is 20min~30min, and the density is pressed to more than 90%. The thickness of the pressed powder is 1mm~4mm and the diameter is 10mm~60mm. Step 5-2: Place pure copper sheet 2 on the top and bottom of the preform, and press it again to make the copper sheet stably cover the preform, to obtain copper-clad preform 3; the thickness of pure copper sheet 2 is 0.05mm~2mm; Step 6: Place the graphite pressure column 1 and the copper-clad preform 3 into the mold in sequence and assemble them into a component; The mold sleeve in step 6 includes a graphite mold sleeve 4 and a steel mold sleeve 5; The specific assembly operation is as follows: First, put the graphite mold sleeve 4 into the steel mold sleeve 5, and then put the graphite pressure column 1, copper-clad preform 3, and graphite pressure column 1 into the graphite mold sleeve 4 in sequence. The thickness of the graphite pressure column 1 is selected according to the actual needs. After the assembly is completed, the top surface of the upper graphite pressure column 1 is higher than the height of the mold sleeve. The inner diameter of the mold sleeve is selected according to the diameter of the copper-clad preform. If multiple copper-clad preforms 3 need to be sintered simultaneously, multiple copper-clad preforms are stacked between two layers of graphite pressure columns 1, and graphite carbon paper 6 is used to separate each two layers of copper-clad preforms; the thickness of graphite carbon paper 6 is 0.5mm~1mm. Step 7: Heat and sinter the components; Step 8: Remove excess parts and oxide film generated during sintering from the component to obtain porous diamond copper composite material.

Claims

1. A method for preparing a porous diamond-copper composite material, characterized in that, The specific steps are as follows: Step 1: Perform plasma cleaning on the porous diamond powder on the surface; Step 2: Coat the diamond surface with a strong carbon metal; Step 3: Plate a copper layer on the surface of the strong carbon metal; Step 4: Perform heat treatment to obtain diamond copper-based composite material powder; Step 5: Press the powder-coated pure copper sheet (2) to obtain a copper-coated preform (3). Step 6: Place the graphite pressure column (1) and the copper-clad preform (3) into the mold in sequence and assemble them into a component; Step 7: Heat and sinter the components; Step 8: Remove excess parts and oxide film generated during sintering from the component to obtain porous diamond copper composite material.

2. The method for preparing the porous diamond-copper composite material according to claim 1, characterized in that, The specific operation of step 1 is as follows: the porous diamond powder is placed in the vacuum chamber of the plasma cleaner, and then argon gas is used to generate high-energy plasma through DC power supply to bombard the surface of the porous diamond. At the same time, the ultrasonic vibration platform is used to make each surface of the diamond roll evenly to complete the plasma cleaning of each surface. The particle size of the porous diamond powder on the surface is 5μm~150μm; During the ignition process, the power supply voltage is 1800V~2200V, the bias voltage is 350V~450V, and the plasma cleaning time is 40min~60min.

3. The method for preparing the porous diamond-copper composite material according to claim 1, characterized in that, The specific operation of step 2 is as follows: a physical magnetron sputtering coating machine is used to metallize the porous diamond surface with strong carbon metal, which is any one of Cr, Zr, W, and Mo; the particle size of the strong carbon metal powder is 0.8μm~5μm. The specific parameters are: coating power of 1200W~1500W, coating time of 10min~30min, and coating thickness of 100nm~300nm.

4. The method for preparing the porous diamond-copper composite material according to claim 1 or 2, characterized in that, The specific operation of step 3 is as follows: Step 3-1: Pre-plat a copper layer on the surface of a strong carbon metal; Pure copper is deposited in a physical magnetron sputtering coating machine. The diamond is uniformly rolled on each side by an ultrasonic vibration platform to complete the copper coating on each side. The specific parameters are: coating power 1200W~1500W, coating time 20min~30min, and coating thickness 100nm~200nm. Step 3-2: Perform a second copper plating; Copper plating is performed using a barrel plating machine; the barrel plating machine has a current of 7A~10A, a speed of 15r / min~30r / min, and a plating thickness of 5nm~50nm.

5. The method for preparing the porous diamond-copper composite material according to claim 1, characterized in that, The heat treatment in step 4 is carried out in a high-vacuum reduction furnace, with a vacuum level not exceeding 5 × 10⁻⁶. -3 Pa, sintering temperature 850℃~950℃, holding time 40min~60min.

6. The method for preparing the porous diamond-copper composite material according to claim 1, characterized in that, Step 5 specifically includes the following steps: Step 5-1: Press the powder obtained in step 4 to obtain a preform. The pressure is 60MPa~100MPa, the holding time is 20min~30min, and the density is pressed to more than 90%. The thickness of the pressed powder is 1mm~4mm and the diameter is 10mm~60mm. Step 5-2: Place pure copper sheets (2) on the top and bottom of the preform and press it again to make the copper sheets stably cover the preform, and obtain copper-clad preform (3); the thickness of the pure copper sheet (2) is 0.05mm~2mm.

7. The method for preparing the porous diamond-copper composite material according to claim 1 or 6, characterized in that, The mold in step 6 includes a graphite mold (4) and a steel mold (5). The specific assembly operation is as follows: First, put the graphite mold sleeve (4) into the steel mold sleeve (5), and then put the graphite pressure column (1), copper-clad preform (3), and graphite pressure column (1) into the graphite mold sleeve (4) in sequence. The thickness of the graphite pressure column (1) is selected according to the actual needs. After the assembly is completed, the top surface of the upper graphite pressure column (1) is higher than the height of the mold sleeve. The inner diameter of the mold sleeve is selected according to the diameter of the copper-clad preform. If multiple copper-clad preforms (3) need to be sintered at the same time, multiple copper-clad preforms are stacked between two layers of graphite pressure columns (1), and graphite carbon paper (6) is used to separate each two layers of copper-clad preforms; the thickness of the graphite carbon paper (6) is 0.5mm~1mm.

8. The method for preparing the porous diamond-copper composite material according to claim 1, characterized in that, The specific operation of heating and sintering in step 7 is as follows: the component is heated using a hot pressing sintering machine. The hot pressing sintering temperature is 900℃~1050℃, the holding time is 20min~40min, the heating rate is 6℃ / min~8℃ / min, the holding pressure is 40MPa~60MPa, and after the heating is stopped, the pressure is held for 60min~120min, and then naturally cooled to room temperature before being taken out.

9. The method for preparing the porous diamond-copper composite material according to claim 7, characterized in that, The specific operation of step 8 is as follows: remove the graphite mold sleeve (4), steel film sleeve (5) and graphite pressure column (1) from the component, then use a polishing machine to perform preliminary polishing on the copper oxide film generated after the copper sheet is sintered, and finally use dilute hydrochloric acid to remove the remaining copper oxide film on the surface.

10. A porous diamond-copper composite material, characterized in that, The composite material is prepared using the method described in any one of claims 1 to 9. It consists of a composite powder and a copper coating layer. The powder consists of a porous diamond, a strong carbon metal layer, and a copper layer from the inside out. The density of the composite powder is not less than 96%. The particle size of the porous diamond powder is 5 μm to 150 μm.

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