CN117532002A - A preparation method for flaky diamond metal matrix composite materials with high thermal conductivity and high surface finish - Google Patents

Abstract

A method for preparing a flaky diamond metal matrix composite material with high thermal conductivity and high surface finish, and relates to a method for preparing a diamond metal matrix composite material. In order to solve the problem that existing high thermal conductivity flake diamond metal matrix composite materials are difficult to process. The invention regulates the arrangement direction of single crystal diamond particles through the layering process, thereby providing a good surface state for subsequent precision grinding and polishing, and achieving a higher surface finish. The upper and lower surfaces of the obtained diamond metal matrix composite material are metal layers of specific thickness, which are easy to process and provide convenient conditions for subsequent processing, shaping, precision grinding, electroplating and welding. And due to the improvement of the process method, the overall thermal conductivity of the obtained diamond metal matrix composite material is high, and the process is simple. The preparation cycle is short.

Description

A flaky diamond metal matrix composite material with high thermal conductivity and high surface finish Preparation

Technical field

The invention relates to a method for preparing diamond metal matrix composite materials.

Background technique

With the continuous improvement of the power and integration of various devices, traditional heat-conducting materials have gradually been unable to meet the demand. High-thermal conductive diamond/copper composite materials, as a new generation of thermal management materials, have excellent thermal conductivity and low thermal expansion coefficient. , widely used in integrated heat sinks, laser diode heat sinks, solid-state laser heat sinks, CPU heat sinks or heat sinks, high-power electronic device substrates (such as IGBT substrates), LED and HB-LED heat sinks, RF and microwave packaging Heat sinks, microelectronic packaging heat sinks, thermal management materials for high heat load electronic devices and many other fields can be upgraded to replace traditional thermal conductive materials, significantly reducing device temperature rise.

Due to the high volume fraction and large particle size of diamond in existing flaky diamond metal matrix composite materials, it is unavoidable to process single crystal diamond particles during processing. Because single crystal diamond particles are extremely hard and copper is very soft, this material cannot be threaded, ground, or polished like conventional metal materials. When grinding and polishing, it is not only difficult to achieve the surface finish of conventional metal materials, but also the thermal conductivity of the material will be lost.

The existing flaky high thermal conductivity diamond metal matrix composite materials are coated with copper on the surface of the diamond metal matrix composite materials, so that the surface of the diamond metal matrix composite materials is a metal layer without single crystal diamond particles, which is easier to process, but this method requires the use of Air pressure impregnation equipment and plasma discharge sintering equipment are used to complete the preparation of raw materials, which is not conducive to the development of a batch and low-cost raw material preparation method. Patent CN112974809B melts the base metal or alloy as a whole and allows it to flow around the single crystal diamond particles. It uses a specific device to apply air pressure to compound it to form a diamond-copper composite material. Then, the surface of the diamond-copper composite material and the copper layer are The discharge micro-areas are melted and combined under pressure. The discharge in this method only occurs between the composite material and the surface layer. The surface finish of the composite material prepared by this method is better than 0.8 μm, which is far from meeting the demand. If the surface finish of the prepared composite material can be improved, it will facilitate subsequent grinding and polishing. Therefore, it is urgent to develop a preparation method that can maintain the high thermal conductivity of flake diamond metal matrix composite materials while maintaining its high surface finish.

Contents of the invention

In order to solve the problem that existing high thermal conductivity flake diamond metal matrix composite materials are difficult to process, the present invention proposes a method for preparing high thermal conductivity and high surface finish flake diamond metal matrix composite materials in a single device. The surface smoothness of the prepared flake diamond metal matrix composite material is 0.012 μm-0.04 μm.

The preparation method of the flaky diamond metal matrix composite material with high thermal conductivity and high surface finish of the present invention is carried out according to the following steps:

1. Screen single crystal diamond particles, wash them with acid, alkali and absolute ethanol in sequence, and dry them;

2. The surface of single crystal diamond particles is uniformly plated with a metal coating with a thickness of 10 to 100 nanometers, and the surface roughness of the metal coating is between 1 and 10 nanometers;

3. Spread metal foil on the bottom of the mold;

4. Spread metal powder on the metal foil;

5. Spread single crystal diamond particles on the metal powder. During the tiling process, adjust the arrangement of the single crystal diamond particles under a stereo microscope so that one (100) crystal face of the single crystal diamond particles faces upward and the (100) crystal faces face each other. The tilt angle of the metal foil is 0 to 15°; the gap between adjacent single crystal diamond particles does not exceed 50 μm, and particle stacking does not occur;

6. Fill the gaps between single crystal diamond particles with metal powder until it is flush with the highest point of the single crystal diamond particles;

7. Lay the same metal foil as in step 3 on the surface of the single crystal diamond particles and metal powder;

8. Place the mold in the plasma discharge sintering equipment;

9. Evacuate the plasma discharge sintering equipment, raise the temperature to 100-200°C below the melting point of the metal foil at a speed of 50-60K/min, and keep it warm for 10-60 minutes, so that the metal coating on the diamond surface reacts with the single crystal diamond particles. Generate metal carbides, causing the metal powder to react with single crystal diamond particles to generate metal carbides;

10. Then heat the plasma discharge sintering equipment to 20-50°C below the melting point of the base metal at a speed of 10-20K/min. After reaching the temperature, apply a pressure of 10-50MPa and maintain heat and pressure for 10-60 minutes to achieve pressurized composite;

11. Cool down the plasma discharge sintering equipment to room temperature, release the pressure, remove the vacuum, and demould, and it is completed.

The principles and beneficial effects of the present invention are:

1. The present invention proposes a method for preparing high thermal conductivity flake diamond metal matrix composite materials in a single device. The upper and lower surfaces of the obtained diamond metal matrix composite material are metal layers of a specific thickness, which is easy to process and is suitable for subsequent processing and shaping. , precision grinding, electroplating and welding provide convenient conditions. And due to the improvement of the process method, the overall thermal conductivity of the obtained diamond metal matrix composite material is high, and the process is simple.

2. The present invention uses a discharge plasma sintering method to form a metallurgical bond between single crystal diamond particles coated with metal films, metal powder and metal foil. The reaction time is short, the organizational structure of the interface layer can be controlled, and the thermal stability of the single crystal diamond particles can be controlled. The damage is small, and the present invention can control the arrangement direction of single crystal diamond particles.

3. The present invention has a short preparation cycle and a simple process flow. It can be completed in 3 hours from mold installation to demoulding, and is suitable for mass production.

4. The present invention can achieve more precise control of the thermal conductivity and thermal expansion coefficient of the overall material by controlling the diamond volume fraction, as well as the composition and thickness of the same layer (surface layer).

5. The present invention regulates the arrangement direction of single crystal diamond particles through the layering process, thereby providing a good surface state for subsequent precision grinding and polishing and achieving a higher surface finish.

6. The present invention can realize the preparation of ultra-thin high thermal conductivity diamond metal matrix composite materials with a thickness of 0.12mm. The middle layer of the composite material is single crystal diamond particles, and the upper and lower layers are a metal matrix or an alloy of a metal matrix. The thermal conductivity of the composite material The rate is 700~1000W/(m·K), the surface finish is 0.012μm-0.04μm, and the thickness is 0.12~6mm.

The differences between this application and "A method of coating copper on the surface of diamond/copper composite materials, CN112974809A" are: 1. The equipment used is different. This application only uses one piece of plasma discharge sintering equipment to complete the material preparation, that is, to obtain a monolithic material in which the middle layer is made of diamond particles and the upper and lower surfaces are made of copper or copper alloy. CN112974809A requires the use of two pieces of equipment: air pressure impregnation and plasma discharge sintering to achieve copper coating on the surface of the diamond copper composite material. ②. The composite process of materials is different. In this application, the surface coating of diamond particles and the surrounding copper powder are melted in the integral discharge micro-area and pressed to form a sheet material. CN112974809A is to melt the matrix alloy as a whole, then flow it around the diamond particles, and use a specific device to apply air pressure to compound it to form a diamond-copper composite material. Then, discharge micro-areas occur on the surface of the diamond-copper composite material and the copper layer. Melted and held together by pressure. That is, the range of areas where discharge occurs is different. Discharge in this application occurs throughout the material. The discharge of CN112974809A only occurs between the composite material and the surface layer. In this application, the metal powder is melted in the discharge micro-area and then pressed and compounded, so the entire preparation cycle is short and man-hours are saved. CN112974809A requires the bulk metal to be melted and prepared, and the overall working hours are very long. ③. The properties of the prepared materials are different. The surface finish of the composite material prepared by CN112974809A is better than 0.8 μm. The surface finish of the composite material prepared by this application is 0.012-0.04 μm, and the surface finish is improved by one order of magnitude. Since the (100) crystal plane of the diamond particles is made parallel to the material surface during the laying process, the exposed corners of the diamond particles are reduced, thus enabling higher surface finish to be achieved in subsequent processing. CN112974809A cannot control the arrangement of diamond particles. The angular outcrops of diamond particles will be embedded in the copper layer, which is equivalent to embedding hard points in the soft matrix, making subsequent grinding and polishing difficult.

The differences between this application and "A near-net forming method for ultra-thin thickness diamond/copper composite materials, CN114147223A" are: ①. The properties of the prepared materials are different. The thermal conductivity of the material prepared by CN114147223A is the highest 434W/mK. The thermal conductivity of the material prepared in this application is 700-1000W/mK. ②. This application regulates the degree of discharge by regulating the thickness and surface roughness of the surface coating of diamond particles to obtain an ideal interface and better thermal conductivity. CN114147223A limits the coating element to tungsten, but does not limit the coating thickness and surface roughness. If high-quality interface bonding is to be achieved, in addition to precise control of process parameters, surface roughness also needs to be limited. Surface roughness affects the current distribution, temperature distribution, and sample structure during the plasma discharge process. This application limits the thickness of the coating on the surface of diamond particles to 10 to 100 nanometers, and the surface roughness of the coating to be between 1 and 10 nanometers. This ensures uniform discharge during the material preparation process to a certain extent, ensures that the current and temperature are nearly uniformly distributed within the composite material block during the plasma discharge process, reduces the temperature gradient, and also reduces the inhomogeneity of the structure and composition. CN114147223A only limits the particle size of diamond particles and copper powder, and does not limit the thickness and surface roughness of the tungsten coating. The thermal conductivity of the flaky diamond metal matrix composite material obtained in this application is 700-1000W/mK, and the thermal conductivity of the material prepared by CN114147223A is the highest 434W/mK. (Embodiment 1 of CN114147223A), the lowest thermal conductivity of this application is 266W/mK higher than the highest thermal conductivity of CN114147223A. After the thermal conductivity of the material prepared in this application is improved, the application scope of this material is expanded, it is easier to achieve mass production, and the heat sink device prepared has better heat dissipation effect. ③. This application regulates the arrangement of diamond particles. CN114147223A does not regulate the arrangement of diamond particles. Since the (100) crystal plane of the diamond particles is made parallel to the material surface during the laying process, the exposed corners of the diamond particles are reduced, thus enabling higher surface finish to be achieved in subsequent processing.

The differences between this application and "A metal base diamond product and its preparation method, CN115365505A" are: ①. The preparation process of the material is different. CN115365505A uses a hot pressing sintering method to prepare the material, and applies pressure to the material preform at high temperature to make it Densification, no discharge process. This application uses a plasma discharge sintering method to prepare materials. The material preform is melted and pressurized by discharge in micro-areas in a vacuum environment. This application is simpler and more convenient to implement. ②. This application regulates the arrangement of diamond particles, while CN115365505A does not regulate the arrangement of diamond particles. Since the (100) crystal plane of the diamond particles is made parallel to the material surface during the laying process, the exposed corners of the diamond particles are reduced, thus enabling higher surface finish to be achieved in subsequent processing. The subsequent grinding and polishing of the material in this application is performed on the metal matrix. The grinding and polishing of the material in CN115365505A is performed on the basis of the coexistence of diamond particle outcrops and the metal matrix. Therefore, the grinding and polishing of CN115365505A is more difficult. CN115365505A Example 1 "The diamond is selected from 12/14 mesh uncoated diamonds", the mesh number and size of the screen correspond to 12 mesh: 1397 μm, 14 mesh: 1165 μm. That is, the diamond particle size exceeds 1.1mm. After a series of steps, "the thickness of the diamond product was reduced from 3.25mm to 1mm", indicating that the corners or edges of the diamond particles were ground away. And the surface of the resulting material should be composed of diamond particles and metal. This application does not destroy the diamond particles. Moreover, the upper and lower surfaces of the material obtained by this application are homogeneous surfaces. There is only a metal matrix and no diamond particles exposed, which brings great convenience to subsequent electroplating. ③, CN115365505A Example 1 "The outer matrix is selected from flake copper with a thickness of 1 mm, the inner matrix is selected from flake silver-based alloys with a thickness of 0.5 mm, and the diamond is selected from 12/14 mesh uncoated diamond ". Since diamond does not wet copper or silver, the interface layer between the diamond particles and the surrounding matrix is not an interface layer composed of carbides. This application "uses magnetron sputtering method to uniformly plate a metal coating with a thickness of 50 to 100 nanometers on the surface of diamond particles, and the surface roughness of the coating is between 1 and 10 nanometers." In the subsequent plasma discharge sintering process, the metal coating and Diamond particles react to form metal carbides, so the interface layer between the diamond particles and the surrounding matrix is an interface layer that reacts with each other to form carbides, so the bonding force is stronger.

The differences between this application and "A single-layer diamond abrasive grains ordered arrangement brazing method without template and furnace brazing, CN113524058B" are: 1. The composite process of the materials is different. CN113524058B "Put the substrate to be welded with uniformly arranged diamonds obtained above into a vacuum annealing furnace for brazing, and take out the sample to obtain a brazing tool product with uniformly dense diamonds.""During brazing, in the vacuum annealing furnace The air pressure is controlled below 5×10 ^-3 Pa, the brazing temperature is 900 or 920°C, and the holding time is 5 minutes. CN113524058B has no discharge process. This application uses a plasma discharge sintering method to prepare materials, and the material preform is melted and pressurized by discharge micro-areas in a vacuum environment. In this application, the metal powder is melted in the discharge micro-area and then pressed and compounded. The temperature is low, the time is short, and the thermal damage to the diamond particles is small. ②. The requirements for regulating the arrangement of diamond particles are different. CN113524058B carries out the orderly arrangement of abrasive grains. "First, cut out an appropriate amount of tape and stick it on the lower part of the screen. Then take a certain amount of diamond abrasive grains and spread it on the area where the tape is attached on the lower part of the screen. Use a brush to disperse the stacked diamond particles. , then use compressed air to blow off the diamond abrasive grains on the surface of the tape that are not stuck by the tape, and finally slowly peel off the arranged tape from the screen." The entire process does not control a certain crystal plane of the diamond particles to be parallel to the surface, but only ensures that the diamond particles are not stacked. This application "regulates the arrangement of diamond particles during the layering process so that the (100) crystal plane of the diamond particles is parallel to the upper and lower surfaces of the overall material;". In this application, since the (100) crystal plane of the diamond particles is parallel to the upper and lower surfaces of the overall material, the exposed corners of the diamond particles are reduced, and therefore a higher surface finish can be achieved in subsequent processing. ③. The performance requirements of the prepared materials are different. CN113524058B is to obtain composite materials with high hardness, high strength and good wear resistance, while the purpose of this application is to obtain composite materials with high thermal conductivity. ④. The interface bonding states between diamond particles and matrix are different. CN113524058B does not have the step of controlling the interface, and the surface of the diamond particles is not plated. If the base metal is a metal that can react with diamond to form carbide, such as aluminum or iron, the interface bonding will be stronger. If the base metal is copper, silver, or other metal that does not wet diamond, the interface bonding will be very weak. The plan adopted in this application is to "first raise the temperature to 100-200°C below the melting point of the base metal at a speed of 50-60K/min and keep it for 10-60 minutes to control the interface; then raise the temperature to the melting point of the base metal at a speed of 10-20K/min. below 20~50℃, then apply pressure of 10~50MPa, maintain heat and pressure for 10~60min to achieve pressure compounding; raise the temperature to 100~200℃ below the melting point of the metal foil at a speed of 50~60K/min and keep it warm for 10~60min , the metal coating on the diamond surface reacts with the single crystal diamond particles to form metal carbides, and the metal powder reacts with the single crystal diamond particles to form metal carbides; then the temperature is raised to 20~ below the melting point of the base metal at a speed of 10~20K/min. 50°C, after reaching the temperature, apply a pressure of 10 to 50MPa and keep the temperature and pressure for 10 to 60 minutes to achieve pressurized composite;" it is possible to obtain higher thermal conductivity by controlling the interface layer between diamond particles and metal matrix.

The differences between this application and "A diamond-layered copper-based high thermal conductivity composite material and its preparation method, CN109808258A" are: 1. The composite process of the materials is different. CN109808258A is prepared through pier pressing, welding, and hot pressing processes, and there is no discharge sintering process. The entire process takes place at 200°C below the melting point. In this application, the metal powder is melted in discharge micro-areas and then pressed and compounded, so the entire preparation process has fewer steps, a shorter cycle, and saves man-hours. The technical solution of this application requires the manual assembly of metal foils, diamond particles, and metal foils; and then the preparation is completed in plasma discharge sintering equipment. The technical solution of CN109808258A requires that metal foil, copper mesh or foamed copper, diamond particles, and metal foil be cold-pressed and assembled first; then the cold-pressed and assembled materials are subjected to ultrasonic rolling solid phase welding; and then heated in a vacuum state. Pressure diffusion welding. The overall process is many, the cycle is long, and the working hours are long. ②. CN109808258A does not provide the surface finish of the prepared material. CN109808258A records that the diamond particles are evenly dispersed on the copper mesh or copper foam, and the mesh number of the copper mesh is 35-150 mesh. According to the mesh size comparison table, 35 mesh is 0.425mm, and 150 mesh is 0.425mm. The mesh size is 0.106mm. CN109808258A simply disperses diamond particles on a copper mesh or copper foam without any requirements on the direction of the diamond particles. Therefore, in the final material obtained, it is very likely that the edges or tips of the diamond particles are at the top and bottom. On the layer of copper foil, diamond particles even appeared during the subsequent pressurization process. Seriously affects the surface quality of the material. In this application, diamond particles with metal coating are laid flat on the surface of metal sheets; during the laying process, the arrangement of the diamond particles is controlled so that the (100) crystal plane of the diamond particles is parallel to the upper and lower surfaces of the overall material. Making the (100) crystal plane of the diamond particles parallel to the surface of the material reduces the outcropping of edges and corners of the diamond particles, thus enabling higher surface finish to be achieved in subsequent processing. ③. The interface bonding states between diamond particles and matrix are different. CN109808258A does not give the thermal conductivity of the prepared material. According to claim 5 of CN109808258A, the surface of the diamond particles is coated with a thin metal layer by magnetron sputtering or cold spraying. The thickness of the thin layer is between 1-20 μm, in the embodiment, it is 15 μm and 16 μm. In claim 6, metal foil, copper mesh or foamed copper, diamond particles, and metal foil are sequentially placed to complete the cold pressing assembly of the material; the cold pressed assembled material is subjected to ultrasonic rolling solid phase welding; and thermal processing is performed in a vacuum state. "Pressure diffusion welding to complete the preparation of diamond-layered copper-based high thermal conductivity composite materials" without interface control steps and processes. At present, cold spraying cannot evenly coat the surface of granular powder materials and can only evenly coat the surface of bulk materials. Coating. This application adopts "Use magnetron sputtering method to uniformly coat the surface of diamond particles with a metal coating with a thickness of 50 to 100 nanometers, and the surface roughness of the coating is between 1 and 10 nanometers." At the same time, it adopts "with a temperature of 50 to 60K/min The temperature is raised to 100-200°C below the melting point of the metal foil and kept for 10-60 minutes, so that the metal coating on the diamond surface reacts with the single crystal diamond particles to form metal carbides, and the metal powder reacts with the single crystal diamond particles to form metal carbides. ; Then, the temperature is raised to 20-50°C below the melting point of the base metal at a speed of 10-20K/min. After reaching the temperature, a pressure of 10-50MPa is applied and the temperature and pressure are maintained for 10-60min to achieve the technical solution of "pressure compounding", which can achieve control The interface layer between the diamond particles and the metal matrix (the metal coating on the diamond surface reacts with the diamond particles to form metal carbides, and the metal powder reacts with the diamond particles to form metal carbides) to obtain higher thermal conductivity. The diamond particles of this application The thickness of the surface coating is more than 1 order of magnitude different from that of CN109808258A. If the interface layer is too thick, it will increase the interface thermal resistance and reduce the thermal conductivity of the material. (4) This application uses a single layer of diamond particles, which is easier to achieve thermal short circuit in principle, that is There is no interfacial thermal resistance between multiple layers, so the overall thermal conductivity of the material can be greatly improved. CN109808258A is a multi-layer diamond particle. The copper mesh or copper foam will remain in the matrix, introducing a new interface and reducing the copper content. Thermal conductivity of the substrate.

Description of drawings

Figure 1 is a cross-sectional photograph of the flaky diamond metal matrix composite material in Example 1. In the figure, a is a (100) crystal plane of a single crystal diamond particle;

Figure 2 shows the surface morphology of single crystal diamond particles of the flaky diamond metal matrix composite material in Example 1;

Figure 3 shows the surface morphology of single crystal diamond particles of the flaky diamond metal matrix composite material in Example 2.

Detailed ways

The technical solution of the present invention is not limited to the specific implementations listed below, but also includes any reasonable combination between specific implementations.

Specific Embodiment 1: In this embodiment, the preparation method of the flaky diamond metal matrix composite material with high thermal conductivity and high surface finish is carried out according to the following steps:

1. Screen single crystal diamond particles, wash them with acid, alkali and absolute ethanol in sequence, and dry them;

2. The surface of single crystal diamond particles is uniformly plated with a metal coating with a thickness of 10 to 100 nanometers, and the surface roughness of the metal coating is between 1 and 10 nanometers;

3. Spread metal foil on the bottom of the mold;

4. Spread metal powder on the metal foil;

5. Spread single crystal diamond particles on the metal powder. During the tiling process, adjust the arrangement of the single crystal diamond particles under a stereo microscope so that one (100) crystal face of the single crystal diamond particles faces upward and the (100) crystal faces face each other. The tilt angle of the metal foil is 0 to 15°; the gap between adjacent single crystal diamond particles does not exceed 50 μm, and particle stacking does not occur;

6. Fill the gaps between single crystal diamond particles with metal powder until it is flush with the highest point of the single crystal diamond particles;

7. Lay the same metal foil as in step 3 on the surface of the single crystal diamond particles and metal powder;

8. Place the mold in the plasma discharge sintering equipment;

9. Evacuate the plasma discharge sintering equipment, raise the temperature to 100-200°C below the melting point of the metal foil at a speed of 50-60K/min, and keep it warm for 10-60 minutes, so that the metal coating on the diamond surface reacts with the single crystal diamond particles. Generate metal carbides, causing the metal powder to react with single crystal diamond particles to generate metal carbides;

10. Then heat the plasma discharge sintering equipment to 20-50°C below the melting point of the base metal at a speed of 10-20K/min. After reaching the temperature, apply a pressure of 10-50MPa and maintain heat and pressure for 10-60 minutes to achieve pressurized composite;

11. Cool down the plasma discharge sintering equipment to room temperature, release the pressure, remove the vacuum, and demould, and it is completed.

1. This embodiment proposes a method for preparing high thermal conductivity flake diamond metal matrix composite materials in a single device. The upper and lower surfaces of the obtained diamond metal matrix composite material are metal layers of a specific thickness, which is easy to process and is suitable for subsequent processing. Forming, precision grinding, electroplating and welding provide convenient conditions. And due to the improvement of the process method, the overall thermal conductivity of the obtained diamond metal matrix composite material is high, and the process is simple.

2. This embodiment uses a discharge plasma sintering method to form a metallurgical bond between single crystal diamond particles coated with metal films, metal powder and metal foil. The reaction time is short, the organizational structure of the interface layer can be controlled, and the single crystal diamond particles Thermal damage is small, and this embodiment can control the arrangement direction of single crystal diamond particles.

3. This embodiment has a short preparation cycle and a simple process flow. It can be completed in 3 hours from mold installation to demoulding, and is suitable for mass production.

4. This embodiment can achieve more precise control of the thermal conductivity and thermal expansion coefficient of the overall material by controlling the diamond volume fraction, as well as the composition and thickness of the same layer (surface layer).

5. This embodiment regulates the arrangement direction of single crystal diamond particles through the layering process, thereby providing a good surface state for subsequent precision grinding and polishing, and achieving a higher surface finish.

6. This embodiment can realize the preparation of ultra-thin high thermal conductivity diamond metal matrix composite materials with a thickness of 0.12mm. The middle layer of the composite material is single crystal diamond particles, and the upper and lower layers are a metal matrix or an alloy of a metal matrix. The thermal conductivity of the composite material The conductivity is 700~1000W/(m·K), the surface finish is 0.012μm-0.04μm, and the thickness is 0.12~6mm.

Specific Embodiment 2: The difference between this embodiment and Specific Embodiment 1 is that the size of the single crystal diamond particles described in step one is 100 μm to 1200 μm.

Specific Embodiment 3: The difference between this embodiment and Specific Embodiment 1 or 2 is that the metal plating material in step two is W, Cr, Mo, Ti or Zr.

Specific Embodiment 4: The difference between this embodiment and one of Embodiments 1 to 3 is that the metal plating layer described in step 2 is prepared by a magnetron sputtering process, the temperature is 300~400°C, the current is 0.5~1.5A, and the resulting metal The coating is polycrystalline.

Specific Embodiment 5: The difference between this embodiment and one of Specific Embodiments 1 to 4 is that the thickness of the metal foil in step three is 0.01 to 3 mm.

Specific Embodiment Six: The difference between this embodiment and one of the specific embodiments one to five is that the material of the metal foil in step three is copper, copper alloy, aluminum, aluminum alloy, silver or silver alloy.

Specific Embodiment 7: The difference between this embodiment and one of Specific Embodiments 1 to 6 is that the metal powder described in step 4 is Cu powder, Al powder, Ag powder, Ti powder, Cr powder, B powder, Si powder, Zr One or more of powder, W powder, and Mo powder; the diameter of the metal powder does not exceed 100 μm, and the shape of the metal powder is spherical.

Specific Embodiment 8: The difference between this embodiment and one of Specific Embodiments 1 to 7 is that the metal powder described in step 6 is Cu powder, Al powder, Ag powder, Ti powder, Cr powder, B powder, Si powder, Zr One or more of powder, W powder, and Mo powder; the diameter of the metal powder does not exceed 100 μm, and the shape of the metal powder is spherical.

Specific Embodiment 9: The difference between this embodiment and any one of Specific Embodiments 1 to 8 is that in step 9, the plasma discharge sintering equipment is evacuated to a vacuum degree of 10 to 100 Pa.

Specific Embodiment 10: The difference between this embodiment and one of Specific Embodiments 1 to 9 is that the cooling rate when cooling to room temperature in step 11 is 20-40K/min.

Example 1

The preparation method of the flaky diamond metal matrix composite material with high thermal conductivity and high surface finish in this embodiment is carried out according to the following steps:

1. Screen single crystal diamond particles, wash them with acid, alkali and absolute ethanol in sequence, and dry them;

The single crystal diamond particle size is 700 μm;

2. A metal coating with a thickness of 100 nanometers is evenly plated on the surface of single crystal diamond particles, and the surface roughness of the metal coating is 10 nanometers;

The metal plating material is Ti;

The metal coating is prepared by a magnetron sputtering process, the temperature is 300°C, the current is 0.5A, and the resulting metal coating is in a polycrystalline state;

3. Spread metal foil on the bottom of the mold;

The thickness of the metal foil is 0.2mm;

The metal foil is made of pure copper;

4. Spread metal powder on the metal foil;

The metal powder is Cu powder; the diameter of the metal powder is 15 μm, and the shape of the metal powder is spherical;

5. Spread single crystal diamond particles on the metal powder. During the tiling process, adjust the arrangement of the single crystal diamond particles under a stereo microscope so that one (100) crystal face of the single crystal diamond particles faces upward and the (100) crystal faces face each other. The tilt angle of the metal foil is 0 to 15°; the gap between adjacent single crystal diamond particles does not exceed 50 μm, and particle stacking does not occur;

6. Fill the gaps between single crystal diamond particles with metal powder until it is flush with the highest point of the single crystal diamond particles;

The metal powder is Cu powder; the diameter of the metal powder is 15 μm, and the shape of the metal powder is spherical;

7. Lay the same metal foil as in step 3 on the surface of the single crystal diamond particles and metal powder;

8. Place the mold in the plasma discharge sintering equipment;

9. Evacuate the plasma discharge sintering equipment, raise the temperature to 100°C below the melting point of the metal foil at a speed of 50K/min, and keep it warm for 10 minutes, so that the metal coating on the diamond surface reacts with the single crystal diamond particles to generate metal carbides. Metal powder reacts with single crystal diamond particles to form metal carbide;

In step nine, evacuate the plasma discharge sintering equipment until the vacuum degree is 10Pa;

10. Then heat the plasma discharge sintering equipment to 20°C below the melting point of the base metal at a speed of 20K/min. After reaching the temperature, apply a pressure of 10MPa and maintain heat and pressure for 20 minutes to achieve pressurized composite;

11. The plasma discharge sintering equipment is cooled to room temperature, the pressure is released, the vacuum is removed, and the mold is demoulded, and it is completed;

The cooling rate when cooling to room temperature in step 11 is 20K/min.

The thermal conductivity of the flaky diamond copper-based composite material obtained by using the method of Example 1 is 900W/mK. By controlling the arrangement of the single crystal diamond particles in the middle layer and the interface between the single crystal diamond particles and the metal matrix, the preparation of single-layer diamond-copper-based composite materials with high thermal conductivity is achieved. Figure 1 shows the flake diamond metal matrix in Example 1 Cross-sectional photo of the composite material, a in the picture is a (100) crystal plane of the single crystal diamond particle; Figure 2 is the surface morphology of the single crystal diamond particle of the flake diamond metal matrix composite material in Example 1; the thickness of the composite material is 1.1 mm, the thickness of the diamond layer is 0.7mm, and the total thickness of the upper and lower copper layers is 0.4mm.

Example 2

The preparation method of the flaky diamond metal matrix composite material with high thermal conductivity and high surface finish in this embodiment is carried out according to the following steps:

1. Screen single crystal diamond particles, wash them with acid, alkali and absolute ethanol in sequence, and dry them;

The single crystal diamond particle size is 100 μm;

2. A metal coating with a thickness of 50 nanometers is evenly plated on the surface of single crystal diamond particles, and the surface roughness of the metal coating is 10 nanometers;

The metal plating material is W;

The metal coating is prepared by a magnetron sputtering process, the temperature is 400°C, the current is 1.5A, and the resulting metal coating is in a polycrystalline state;

3. Spread metal foil on the bottom of the mold;

The thickness of the metal foil is 0.01mm;

The metal foil is made of pure copper;

4. Spread metal powder on the metal foil;

The metal powder is Cu powder; the diameter of the metal powder does not exceed 100 μm, and the shape of the metal powder is spherical;

5. Spread single crystal diamond particles on the metal powder. During the tiling process, adjust the arrangement of the single crystal diamond particles under a stereo microscope so that one (100) crystal face of the single crystal diamond particles faces upward and the (100) crystal faces face each other. The tilt angle of the metal foil is 0 to 15°; the gap between adjacent single crystal diamond particles does not exceed 50 μm, and particle stacking does not occur;

6. Fill the gaps between single crystal diamond particles with metal powder until it is flush with the highest point of the single crystal diamond particles;

The metal powder is Cu powder; the diameter of the metal powder does not exceed 100 μm, and the shape of the metal powder is spherical;

7. Lay the same metal foil as in step 3 on the surface of the single crystal diamond particles and metal powder;

8. Place the mold in the plasma discharge sintering equipment;

9. Evacuate the plasma discharge sintering equipment, raise the temperature to 100°C below the melting point of the metal foil at a speed of 50K/min, and keep it warm for 20 minutes, so that the metal coating on the diamond surface reacts with the single crystal diamond particles to generate metal carbides. Metal powder reacts with single crystal diamond particles to form metal carbide;

In step nine, evacuate the plasma discharge sintering equipment until the vacuum degree is 10Pa;

10. Then heat the plasma discharge sintering equipment at a speed of 20K/min to 25°C below the melting point of the base metal. After reaching the temperature, apply a pressure of 15MPa and maintain heat and pressure for 60 minutes to achieve pressurized composite;

11. The plasma discharge sintering equipment is cooled to room temperature, the pressure is released, the vacuum is removed, and the mold is demoulded, and it is completed;

The cooling rate when cooling to room temperature in step 11 is 20K/min.

Figure 3 shows the surface morphology of single crystal diamond particles of the flaky diamond metal matrix composite material in Example 2. The thermal conductivity of the flaky diamond copper-based composite material obtained in Example 2 is 750W/mK. By controlling the arrangement of single-crystal diamond particles in the middle layer and the interface combination between single-crystal diamond particles and the metal matrix, a single-layer diamond-copper-based composite material with high thermal conductivity is obtained. The thickness of the composite material is 0.12mm, the thickness of the diamond layer is 0.1mm, the thickness of the upper and lower copper layers are both 0.01mm, and the surface finish is better than 0.012μm.

Example 3

The preparation method of the flaky diamond metal matrix composite material with high thermal conductivity and high surface finish in this embodiment is carried out according to the following steps:

1. Screen single crystal diamond particles, wash them with acid, alkali and absolute ethanol in sequence, and dry them;

The single crystal diamond particle size is 425 μm;

2. A metal coating with a thickness of 10 nanometers is evenly plated on the surface of single crystal diamond particles, and the surface roughness of the metal coating is 1 nanometer;

The metal plating material is Ti;

The metal coating is prepared by a magnetron sputtering process, the temperature is 320°C, the current is 0.7A, and the resulting metal coating is in a polycrystalline state;

3. Spread metal foil on the bottom of the mold;

The thickness of the metal foil is 3mm;

The metal foil is made of pure copper;

4. Spread metal powder on the metal foil;

The metal powder is Ti powder; the diameter of the metal powder does not exceed 30 μm, and the shape of the metal powder is spherical;

5. Spread single crystal diamond particles on the metal powder. During the tiling process, adjust the arrangement of the single crystal diamond particles under a stereo microscope so that one (100) crystal face of the single crystal diamond particles faces upward and the (100) crystal faces face each other. The tilt angle of the metal foil is 0 to 15°; the gap between adjacent single crystal diamond particles does not exceed 50 μm, and particle stacking does not occur;

6. Fill the gaps between single crystal diamond particles with metal powder until it is flush with the highest point of the single crystal diamond particles;

The metal powder is Ti powder; the diameter of the metal powder does not exceed 30 μm, and the shape of the metal powder is spherical;

7. Lay the same metal foil as in step 3 on the surface of the single crystal diamond particles and metal powder;

8. Place the mold in the plasma discharge sintering equipment;

9. Evacuate the plasma discharge sintering equipment, raise the temperature to 120°C below the melting point of the metal foil at a speed of 55K/min, and keep it warm for 20 minutes, so that the metal coating on the diamond surface reacts with the single crystal diamond particles to generate metal carbides. Metal powder reacts with single crystal diamond particles to form metal carbide;

In step nine, the plasma discharge sintering equipment is evacuated to a vacuum degree of 100Pa;

10. Then the plasma discharge sintering equipment is heated to 50°C below the melting point of the base metal at a speed of 10K/min. After reaching the temperature, a pressure of 10MPa is applied and the heat and pressure are maintained for 60 minutes to achieve pressurized composite;

11. The plasma discharge sintering equipment is cooled to room temperature, the pressure is released, the vacuum is removed, and the mold is demoulded, and it is completed;

The cooling rate when cooling to room temperature in step 11 is 40K/min.

The thermal conductivity of the flake diamond aluminum-based composite material obtained in Example 4 is 710W/mK. By controlling the arrangement of the single crystal diamond particles in the middle layer and the interface combination between the single crystal diamond particles and the metal matrix, a single layer with high thermal conductivity is obtained. Diamond copper matrix composites. The thickness of the composite material is 0.2mm, the thickness of the diamond layer is 0.1mm, the thickness of the upper and lower copper layers are both 0.05mm, and the surface finish is better than 0.012μm.

Example 4

The preparation method of the flaky diamond metal matrix composite material with high thermal conductivity and high surface finish in this embodiment is carried out according to the following steps:

1. Screen single crystal diamond particles, wash them with acid, alkali and absolute ethanol in sequence, and dry them;

The single crystal diamond particle size is 100 μm;

2. A metal coating with a thickness of 50 nanometers is evenly plated on the surface of single crystal diamond particles, and the surface roughness of the metal coating is 10 nanometers;

The metal plating material is W;

The metal coating is prepared by a magnetron sputtering process, the temperature is 380°C, the current is 1.2A, and the resulting metal coating is in a polycrystalline state;

3. Spread metal foil on the bottom of the mold;

The thickness of the metal foil is 0.05mm;

The material of the metal foil is pure aluminum;

4. Spread metal powder on the metal foil;

The metal powder is Al powder; the diameter of the metal powder does not exceed 50 μm, and the shape of the metal powder is spherical;

5. Spread single crystal diamond particles on the metal powder. During the tiling process, adjust the arrangement of the single crystal diamond particles under a stereo microscope so that one (100) crystal face of the single crystal diamond particles faces upward and the (100) crystal faces face each other. The tilt angle of the metal foil is 0 to 15°; the gap between adjacent single crystal diamond particles does not exceed 50 μm, and particle stacking does not occur;

6. Fill the gaps between single crystal diamond particles with metal powder until it is flush with the highest point of the single crystal diamond particles;

The metal powder is Al powder; the diameter of the metal powder does not exceed 50 μm, and the shape of the metal powder is spherical;

7. Lay the same metal foil as in step 3 on the surface of the single crystal diamond particles and metal powder;

8. Place the mold in the plasma discharge sintering equipment;

9. Evacuate the plasma discharge sintering equipment, raise the temperature to 100°C below the melting point of the metal foil at a speed of 60K/min, and keep it warm for 60 minutes, so that the metal coating on the diamond surface reacts with the single crystal diamond particles to generate metal carbides. Metal powder reacts with single crystal diamond particles to form metal carbide;

In step nine, evacuate the plasma discharge sintering equipment to a vacuum degree of 50Pa;

10. Then heat the plasma discharge sintering equipment to 30°C below the melting point of the base metal at a speed of 15K/min. After reaching the temperature, apply a pressure of 25MPa and keep the temperature and pressure for 30 minutes to achieve pressurized composite;

11. The plasma discharge sintering equipment is cooled to room temperature, the pressure is released, the vacuum is removed, and the mold is demoulded, and it is completed;

The cooling rate when cooling to room temperature in step 11 is 30K/min.

The thermal conductivity of the flaky diamond-aluminum matrix composite material obtained in Example 4 is 710 W/mK. By controlling the arrangement of single-crystal diamond particles in the middle layer and the interface combination between single-crystal diamond particles and the metal matrix, a single-layer diamond-copper-based composite material with high thermal conductivity is obtained. The thickness of the composite material is 0.2mm, and the thickness of the diamond layer is 0.1mm. , the thickness of the upper and lower copper layers are both 0.05mm, and the surface finish is better than 0.012μm.

Example 5

The preparation method of the flaky diamond metal matrix composite material with high thermal conductivity and high surface finish in this embodiment is carried out according to the following steps:

1. Screen single crystal diamond particles, wash them with acid, alkali and absolute ethanol in sequence, and dry them;

The single crystal diamond particle size is 700 μm;

2. The surface of single crystal diamond particles is evenly coated with a metal coating with a thickness of 30 nanometers, and the surface roughness of the metal coating is 10 nanometers;

The metal plating material is W;

The metal coating is prepared by a magnetron sputtering process, the temperature is 350°C, the current is 1A, and the resulting metal coating is in a polycrystalline state;

3. Spread metal foil on the bottom of the mold;

The thickness of the metal foil is 3mm;

The material of the metal foil is pure aluminum;

4. Spread metal powder on the metal foil;

The metal powder is Al powder; the diameter of the metal powder does not exceed 100 μm, and the shape of the metal powder is spherical;

5. Spread single crystal diamond particles on the metal powder. During the tiling process, adjust the arrangement of the single crystal diamond particles under a stereo microscope so that one (100) crystal face of the single crystal diamond particles faces upward and the (100) crystal faces face each other. The tilt angle of the metal foil is 0 to 15°; the gap between adjacent single crystal diamond particles does not exceed 50 μm, and particle stacking does not occur;

6. Fill the gaps between single crystal diamond particles with metal powder until it is flush with the highest point of the single crystal diamond particles;

The metal powder is Al powder; the diameter of the metal powder does not exceed 100 μm, and the shape of the metal powder is spherical;

7. Lay the same metal foil as in step 3 on the surface of the single crystal diamond particles and metal powder;

8. Place the mold in the plasma discharge sintering equipment;

9. Evacuate the plasma discharge sintering equipment, raise the temperature to 200°C below the melting point of the metal foil at a speed of 58K/min, and keep it warm for 30 minutes, so that the metal coating on the diamond surface reacts with the single crystal diamond particles to generate metal carbides. Metal powder reacts with single crystal diamond particles to form metal carbide;

In step nine, evacuate the plasma discharge sintering equipment to a vacuum degree of 30Pa;

10. Then the plasma discharge sintering equipment is heated to 40°C below the melting point of the base metal at a speed of 18K/min. After reaching the temperature, a pressure of 50MPa is applied and the heat and pressure are maintained for 10 minutes to achieve pressurized composite;

11. The plasma discharge sintering equipment is cooled to room temperature, the pressure is released, the vacuum is removed, and the mold is demoulded, and it is completed;

The cooling rate when cooling to room temperature in step 11 is 25K/min.

The thermal conductivity of the flaky diamond-aluminum matrix composite material obtained in Example 5 is 850 W/mK. By controlling the arrangement of single-crystal diamond particles in the middle layer and the interface combination between single-crystal diamond particles and the metal matrix, a single-layer diamond-copper-based composite material with high thermal conductivity is obtained. The thickness of the composite material is 6.7mm, and the thickness of the diamond layer is 0.7mm. , the thickness of the upper and lower copper layers are both 3mm, and the surface finish is better than 0.012μm.

Example 6

The preparation method of the flaky diamond metal matrix composite material with high thermal conductivity and high surface finish in this embodiment is carried out according to the following steps:

1. Screen single crystal diamond particles, wash them with acid, alkali and absolute ethanol in sequence, and dry them;

The single crystal diamond particle size is 100 μm;

2. A metal coating with a thickness of 80 nanometers is evenly plated on the surface of single crystal diamond particles, and the surface roughness of the metal coating is 10 nanometers;

The metal coating material is Zr;

The metal coating is prepared by a magnetron sputtering process, the temperature is 300°C, the current is 1.2A, and the resulting metal coating is in a polycrystalline state;

3. Spread metal foil on the bottom of the mold;

The thickness of the metal foil is 0.02mm;

The metal foil is made of pure silver;

4. Spread metal powder on the metal foil;

The metal powder is Ag powder; the diameter of the metal powder does not exceed 20 μm, and the shape of the metal powder is spherical;

5. Spread single crystal diamond particles on the metal powder. During the tiling process, adjust the arrangement of the single crystal diamond particles under a stereo microscope so that one (100) crystal face of the single crystal diamond particles faces upward and the (100) crystal faces face each other. The tilt angle of the metal foil is 0 to 15°; the gap between adjacent single crystal diamond particles does not exceed 50 μm, and particle stacking does not occur;

6. Fill the gaps between single crystal diamond particles with metal powder until it is flush with the highest point of the single crystal diamond particles;

The metal powder is Ag powder; the diameter of the metal powder does not exceed 100 μm, and the shape of the metal powder is spherical;

7. Lay the same metal foil as in step 3 on the surface of the single crystal diamond particles and metal powder;

8. Place the mold in the plasma discharge sintering equipment;

9. Evacuate the plasma discharge sintering equipment, raise the temperature to 100°C below the melting point of the metal foil at a speed of 50K/min, and keep it warm for 20 minutes, so that the metal coating on the diamond surface reacts with the single crystal diamond particles to generate metal carbides. Metal powder reacts with single crystal diamond particles to form metal carbide;

In step nine, the plasma discharge sintering equipment is evacuated to a vacuum degree of 40Pa;

10. Then heat the plasma discharge sintering equipment to 20°C below the melting point of the base metal at a speed of 20K/min. After reaching the temperature, apply a pressure of 30MPa and maintain heat and pressure for 20 minutes to achieve pressurized composite;

11. The plasma discharge sintering equipment is cooled to room temperature, the pressure is released, the vacuum is removed, and the mold is demoulded, and it is completed;

The cooling rate when cooling to room temperature in step 11 is 30K/min.

The thermal conductivity of the flaky diamond silver-based composite material obtained in Example 6 is 890 W/mK. By controlling the arrangement of single-crystal diamond particles in the middle layer and the interface combination between single-crystal diamond particles and the metal matrix, a single-layer diamond-copper-based composite material with high thermal conductivity is obtained. The thickness of the composite material is 0.14mm, and the thickness of the diamond layer is 0.1mm. , the thickness of the upper and lower copper layers are both 0.02mm, and the surface finish is better than 0.012μm.

Claims (10)

1. A preparation method of a high-heat conductivity high-surface-finish lamellar diamond metal-based composite material is characterized by comprising the following steps of: the preparation method of the high-heat conductivity high-surface-finish lamellar diamond metal-based composite material comprises the following steps:

1. Screening monocrystalline diamond particles, sequentially carrying out acid washing, alkali washing and absolute ethyl alcohol washing, and drying;

2. uniformly plating a metal coating with the thickness of 10-100 nanometers on the surface of the monocrystalline diamond particles, wherein the surface roughness of the metal coating is 1-10 nanometers;

3. paving a metal foil on the bottom of the die;

4. paving metal powder on the metal foil;

5. spreading monocrystalline diamond particles on the metal powder, and adjusting the arrangement of the monocrystalline diamond particles under a split microscope in the spreading process to enable one (100) crystal face of the monocrystalline diamond particles to face upwards and the inclination angle of the (100) crystal face relative to the metal foil to be 0-15 degrees; gaps between adjacent single crystal diamond particles do not exceed 50 μm, while no stacking of particles occurs;

6. filling metal powder in the gaps of the monocrystalline diamond particles until the metal powder is level with the highest point of the monocrystalline diamond particles;

7. spreading metal foils which are the same as those in the third step on the surfaces of the monocrystalline diamond particles and the metal powder;

8. placing the mold in a plasma discharge sintering device;

9. vacuumizing the plasma discharge sintering equipment, heating to 100-200 ℃ below the melting point of the metal foil at the speed of 50-60K/min, and preserving heat for 10-60 min to enable the metal coating on the diamond surface to react with the monocrystalline diamond particles to generate metal carbide, and enabling the metal powder to react with the monocrystalline diamond particles to generate metal carbide;

10. Then heating the plasma discharge sintering equipment to 20-50 ℃ below the melting point of the matrix metal at the speed of 10-20K/min, applying the pressure of 10-50 MPa after reaching the temperature, and carrying out heat preservation and pressure maintaining for 10-60 min to realize pressurized compounding;

11. and cooling the plasma discharge sintering equipment to room temperature, releasing pressure, discharging vacuum and demoulding.

2. The method for preparing the high-thermal-conductivity high-surface-finish lamellar diamond metal-based composite material according to claim 1, wherein the method comprises the following steps of: the grain size of the single crystal diamond in the step one is 100-1200 mu m.

3. The method for preparing the high-thermal-conductivity high-surface-finish lamellar diamond metal-based composite material according to claim 1, wherein the method comprises the following steps of: and in the second step, the metal coating is W, cr, mo, ti or Zr.

4. The method for preparing the high-thermal-conductivity high-surface-finish lamellar diamond metal-based composite material according to claim 1, wherein the method comprises the following steps of: and step two, preparing the metal coating by adopting a magnetron sputtering process, wherein the temperature is 300-400 ℃, the current is 0.5-1.5A, and the obtained metal coating is in a polycrystalline state.

5. The method for preparing the high-thermal-conductivity high-surface-finish lamellar diamond metal-based composite material according to claim 1, wherein the method comprises the following steps of: and step three, the thickness of the metal foil is 0.01-3 mm.

6. The method for preparing the high-thermal-conductivity high-surface-finish lamellar diamond metal-based composite material according to claim 1, wherein the method comprises the following steps of: and step three, the metal foil is made of copper, copper alloy, aluminum alloy, silver or silver alloy.

7. The method for preparing the high-thermal-conductivity high-surface-finish lamellar diamond metal-based composite material according to claim 1, wherein the method comprises the following steps of: the metal powder is one or more of Cu powder, al powder, ag powder, ti powder, cr powder, B powder, si powder, zr powder, W powder and Mo powder; the diameter of the metal powder is not more than 100 mu m, and the shape of the metal powder is spherical.

8. The method for preparing the high-thermal-conductivity high-surface-finish lamellar diamond metal-based composite material according to claim 1, wherein the method comprises the following steps of: the metal powder is one or more of Cu powder, al powder, ag powder, ti powder, cr powder, B powder, si powder, zr powder, W powder and Mo powder; the diameter of the metal powder is not more than 100 mu m, and the shape of the metal powder is spherical.

9. The method for preparing the high-thermal-conductivity high-surface-finish lamellar diamond metal-based composite material according to claim 1, wherein the method comprises the following steps of: and step nine, vacuumizing the plasma discharge sintering equipment to a vacuum degree of 10-100 Pa.

10. The method for preparing the high-thermal-conductivity high-surface-finish lamellar diamond metal-based composite material according to claim 1, wherein the method comprises the following steps of: in the eleventh step, the cooling speed is 20-40K/min when cooling to room temperature.