Aluminum-coated diamond-aluminum composite material and net-shape forming method thereof

Abstract

The present application belongs to the technical field of composite material preparation, and particularly relates to an aluminum-coated diamond-aluminum composite material and a near-net-shape preparation method thereof. The method comprises the following steps: preparing a copper, silicon carbide or silicon coating on the surface of diamond particles; coating the coated diamond particles with aluminum liquid to form composite particles with an outer aluminum coating; and mixing the composite particles with aluminum powder, and then performing vacuum hot-press sintering at a semi-solid temperature range to realize near-net-shape forming. Through the double modification of "multi-coating + surface aluminum coating" and in combination with the semi-solid vacuum hot-press sintering process, the present application significantly enhances the interface bonding between the diamond and the aluminum matrix and reduces the interface thermal resistance. The surface of the obtained composite material is a dense aluminum layer with low roughness, and no subsequent large-scale machining is required. Through precise size control by a mold, the near-net-shape forming of complex-shaped components can be realized, and the subsequent processing cost is greatly reduced.

Description

Technical Field

[0001] This invention belongs to the field of composite material preparation technology, specifically relating to an aluminum-coated diamond-aluminum composite material and its net near-net-shape preparation method. Background Technology

[0002] As third-generation semiconductor devices (such as GaN and SiC) develop towards higher power density and higher integration, the heat generated increases dramatically, placing extremely high demands on packaging and heat dissipation materials. Diamond has the highest thermal conductivity found in nature, while aluminum combines good thermal conductivity, low density, and low cost. Therefore, diamond-aluminum composites are considered a highly promising next-generation high-performance thermal management material.

[0003] However, diamond and aluminum have extremely poor wettability and a huge difference in their coefficients of thermal expansion. This leads to two key challenges in preparing high-performance composite materials: first, weak interfacial bonding and high interfacial thermal resistance; second, the composite material is extremely difficult and costly to process afterward due to the presence of hard diamond.

[0004] To address these challenges, existing technologies mainly explore two aspects: "interface modification" and "molding process," but both have significant limitations.

[0005] For example, patent document CN113149714A discloses a method for preparing a porous silicon carbide preform, processing it into a specific shape, and then impregnating it with molten aluminum under vacuum pressure. While this method avoids diamond exposure through the surface silicon carbide layer, improving machinability, its process is cumbersome and costly. More importantly, the thermal conductivity of the surface silicon carbide layer is significantly lower than that of the aluminum-diamond material in the core, creating a heat dissipation bottleneck and limiting overall performance. Furthermore, this "preform + impregnation" process has limited near-net-shape forming capability for complex three-dimensional components, and the integrity of the impregnation is difficult to guarantee.

[0006] Another patent document, CN116393677A, discloses a high-throughput preparation method that uses spark plasma sintering pretreatment combined with gas pressure infiltration to study process parameters. This method focuses on high-throughput experimental screening. However, for product manufacturing, its "particle preform + gas pressure infiltration" molding method also fails to solve the problems of surface roughness and machinability after composite material molding, often requiring expensive subsequent finishing. Furthermore, this method still faces challenges in achieving near-net-shape forming of high-density, complex-shaped components.

[0007] In summary, existing technologies struggle to provide a good surface suitable for direct welding and machining while ensuring high thermal conductivity (e.g., CN113149714A); or they focus on experimental research without optimizing the manufacturing process and surface quality of the final product (e.g., CN116393677A). They generally fall short in achieving strong interfacial bonding, low surface roughness, and high-precision near-net-shape forming of complex shapes. Therefore, developing a method for preparing diamond-aluminum composite materials that systematically addresses these issues and offers a relatively simplified process is of significant practical importance. Summary of the Invention

[0008] The purpose of this invention is to provide an aluminum-coated diamond-aluminum composite material and a method for net-to-net forming of the same material, in order to solve the problems of poor interfacial bonding, poor surface quality, high processing difficulty, and difficulty in net-to-net forming of complex shapes in the prior art of diamond-aluminum composite materials.

[0009] The technical solution of the present invention is as follows: On the one hand, a method for preparing aluminum-coated diamond-aluminum composite material is provided, comprising the following steps: S1. Preparation of coated diamond particles: A coating is prepared on the surface of diamond particles, wherein the coating is one of a metallic copper coating, a silicon carbide coating, or a silicon coating. S2. Preparation of aluminum-coated diamond particles: The coated diamond particles obtained in step S1 are spread in a high-temperature mold, and aluminum liquid is poured in to completely immerse them. After cooling, they are crushed and screened to obtain aluminum-coated diamond particles with an outer aluminum layer. S3. Net near-forming sintering: The aluminum-coated diamond particles obtained in step S2 are mixed with aluminum powder and then placed into a mold. The mold is placed in a vacuum hot pressing sintering furnace and pressure is applied within the semi-solid temperature range of aluminum or aluminum alloy for sintering. After cooling and demolding, the net near-forming diamond aluminum composite material is obtained.

[0010] Preferably, in step S1, when the coating is a copper coating, it is prepared by chemical plating; when the coating is a silicon carbide coating, it is prepared by chemical vapor deposition; and when the coating is a silicon coating, it is prepared by physical vapor deposition magnetron sputtering.

[0011] Preferably, step S2 specifically includes: (1) The coated diamond particles are laid in a single layer in a high-temperature mold, and the thickness of the layer is 1.0-1.5 times the diameter of the single particle; (2) Heat industrial pure aluminum or aluminum alloy to 700-850℃ to melt it into molten aluminum; (3) Pour the molten aluminum into the mold at a speed of 5-10 mL / s until the molten aluminum covers the surface of the particles by a height of 0.5-1.0 times the particle diameter, and then let it cool naturally to room temperature; (4) After cooling, the block is crushed and sieved to obtain 20-300 mesh particles, which are aluminum-coated diamond particles.

[0012] Preferably, in step S3, the volume mixing ratio of the aluminum-coated diamond particles to the aluminum powder is 3:(2~7).

[0013] Preferably, in step S3, the process parameters for vacuum hot pressing sintering are: vacuum degree ≤ 5×10⁻³Pa; heating to 300-400℃ at a rate of 5-15℃ / min and holding for 20-30min, then heating to 450-550℃ and holding for 30-60min, then applying a pressure of 30-80MPa at a temperature of 580-650℃ and holding for 40-90min; then cooling to below 200℃ at a rate of 10-25℃ / min and cooling to room temperature in the furnace.

[0014] Preferably, the temperature range of 450-550℃ is the semi-solid temperature range of aluminum or aluminum alloy materials.

[0015] Preferably, in step S3, the mold is a graphite mold customized according to the final shape of the product.

[0016] On the other hand, an aluminum-coated diamond-aluminum composite material is provided, comprising an aluminum matrix and diamond particles dispersed in the aluminum matrix. The surface of the diamond particles has one of a copper coating, a silicon carbide coating, or a silicon coating, and the outer periphery of the coated diamond particles is further covered with an aluminum layer that is metallurgically bonded to the aluminum matrix. The outer surface of the composite material is a dense aluminum or aluminum alloy layer.

[0017] Preferably, when the surface of the diamond particles is coated with a metallic copper coating, the coating forms a metallurgical bonding interface with the aluminum substrate; when the surface of the diamond particles is coated with a silicon carbide coating or a silicon coating, the coating reacts with the aluminum substrate to generate a stable intermediate phase interface.

[0018] Preferably, the composite material has a thermal conductivity of not less than 590 W / (m·K), a density of not less than 90%, and a surface roughness Ra≤1.6μm, and can be directly brazed and conventionally machined.

[0019] Compared with the prior art, the advantages of the present invention are: (1) High interface bonding strength and excellent thermal conductivity: The wettability of diamond and aluminum is improved by the initial modification of the diamond surface coating (Cu, SiC, Si); and the aluminum shell formed by the "aluminum coating" achieves perfect metallurgical bonding with the aluminum matrix during sintering. Under the dual protection, a high-strength and low-thermal-resistance interface is formed, which fully utilizes the high thermal conductivity potential of diamond. The thermal conductivity of the composite material can reach more than 590W / (m·K).

[0020] (2) Good surface quality and strong machinability: The outer surface of the composite material is a dense aluminum layer formed by sintering and fusion, with low roughness (Ra can reach below 1.6μm) and no exposed diamond. The aluminum surface can be directly brazed and welded, and can be precision machined using conventional machining methods, which effectively solves the problems of difficult and high cost of diamond composite material processing, and significantly reduces subsequent processing costs.

[0021] (3) Outstanding near-net forming capability: Combining customized molds and semi-solid sintering process, it can form complex-shaped components (such as heat sinks with ribs, flow channels and steps) in one go with high dimensional accuracy and high material utilization, which is very suitable for mass production of heat dissipation components with integrated structure and function.

[0022] (4) Flexible process and wide adaptability: Three coating solutions are provided, which can be flexibly selected according to the specific requirements of the product such as thermal conductivity, temperature resistance, and cost, and are suitable for different application scenarios such as semiconductor packaging, high temperature wear-resistant devices, and laser heat sinks.

[0023] (5) The process is relatively simple and easy to scale up: Compared with the impregnation method that requires the preparation of porous ceramic preforms, the process flow of the present invention is more direct and the parameter window is clear. Through the effective connection of the two core steps of casting aluminum coating and semi-solid sintering, it is easy to achieve stable process control and large-scale production. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a process flow diagram for preparing the aluminum-coated diamond-aluminum composite material described in this invention. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to specific embodiments.

[0026] Example 1

[0027] like Figure 1 As shown, this embodiment aims to use a copper coating to prepare a high thermal conductivity near-molded heat dissipation substrate for high-power chip packaging, requiring extremely high thermal conductivity and good solderability.

[0028] S1. Preparation of copper-coated diamond particles a. Select synthetic diamond particles with a particle size of 200 μm, ultrasonically clean them with ethanol for 20 min, and dry them in an oven at 110 ℃ for 3 h.

[0029] b. A dense copper coating of approximately 1 μm thickness is deposited on the surface of the cleaned diamond particles using a chemical copper plating process. Specific process parameters are: alkaline copper plating solution, temperature 60℃, and plating time 40 min.

[0030] c. After plating, the particles are dried at 120℃ for 1.5h to obtain copper-coated diamond particles.

[0031] S2. Preparation of aluminum-coated copper diamond particles a. Lay the above-mentioned particles in a single layer in a graphite flat mold, ensuring that the particles do not overlap, with a layer thickness of approximately 250 μm.

[0032] b. Heat industrial pure aluminum (Al≥99.7%) to 750℃ in a resistance furnace to melt it, add 0.2% refining agent to degas it and keep it at that temperature for 25 minutes.

[0033] c. Pour the molten aluminum into the mold at a rate of about 8 mL / s until the molten aluminum submerges the particle layer by about 150 μm (i.e., the total height is about 400 μm), and then allow it to cool naturally in the air to room temperature.

[0034] d. After cooling, the aluminum-diamond composite sheet is crushed, sieved, and 30-300 mesh particles are selected to obtain aluminum-coated copper-coated diamond particles with an aluminum shell uniformly coated on the outside.

[0035] Through this casting process, molten aluminum can evenly coat each coated diamond particle, forming a complete "aluminum shell" after cooling. This "aluminum shell" will serve as a bridge for perfect integration with the aluminum powder matrix during subsequent sintering, and is key to achieving low interfacial thermal resistance and good surface quality.

[0036] S3, Net Near-Shape Sintering a. Mix the above-mentioned aluminum-coated particles with atomized pure aluminum powder (particle size about 30μm) at a volume ratio of 1:1 and mix for 4 hours.

[0037] b. Fill the mixture into a prefabricated graphite mold with a contoured flow channel structure. The mold cavity is the shape of the target heat dissipation substrate (40mm×40mm×3mm, with fins on the back).

[0038] c. Place the mold in a vacuum hot pressing sintering furnace and evacuate to a vacuum level of 5×10⁻⁶. -3 Below Pa. Heat to 350℃ at 10℃ / min and hold for 25 min, then heat to 500℃ (semi-solid range of pure aluminum) and hold for 45 min. Then heat to 620℃, apply a pressure of 50 MPa, and hold at this temperature and pressure for 60 min.

[0039] d. After the heat preservation is completed, the temperature is programmed to drop to 200℃ at a rate of 15℃ / min, and then the power is turned off and the furnace is cooled to room temperature.

[0040] e. Demolding yields a nearly perfectly formed diamond-aluminum composite heat dissipation substrate.

[0041] This process applies pressure to the semi-solid region of aluminum, allowing the aluminum shell on the outer layer of the aluminum-coated particles to fully diffuse and fuse with the aluminum powder matrix, forming a strong interface bond and a dense structure. At the same time, a customized mold directly imparts the final shape to the product, achieving a balance between high performance and near-net-shape forming.

[0042] The substrate underwent performance testing: the thermal conductivity, measured using the laser scintillation method, reached 615 W / (m·K); the density, measured using Archimedes' displacement method, was 99.2%; the surface roughness Ra was 1.2 μm; and the back-side fins were intact with dimensional tolerances within ±0.1 mm. The substrate surface can be directly plated with nickel-gold for chip soldering, or it can be directly machined, such as through drilling.

[0043] Example 2

[0044] This embodiment aims to prepare a high-temperature resistant near-net-shape wear-resistant ring using a silicon carbide coating for wear-resistant components working in high-temperature environments, requiring good high-temperature interface stability and certain mechanical strength.

[0045] S1. Preparation of silicon carbide coated diamond particles a. Select diamond particles with a particle size of 100 μm, and clean and dry them as in Example 1.

[0046] b. A SiC coating with a thickness of approximately 0.5 μm was deposited on the surface of diamond particles using a hot-wire chemical vapor deposition (CVD) system with silane and methane as reactant gases and hydrogen as carrier and diluent gases. The deposition temperature was 1100℃ and the deposition time was 90 min.

[0047] c. Post-coating treatment is the same as in Example 1.

[0048] S2, Preparation of aluminum-silicon carbide coated diamond particles The process is similar to step S2 in Example 1, except that the thickness of the molten aluminum layer is approximately 120 μm, the molten aluminum used is an aluminum-silicon alloy (melted at 800°C), and the molten aluminum is submerged to a height of approximately 80 μm. After cooling and crushing, 30-300 mesh particles are sieved.

[0049] S3, Net Near-Shape Sintering a. Aluminum-coated particles and aluminum-silicon alloy powder are mixed at a volume ratio of 2:3.

[0050] b. Fill the ring-shaped graphite mold (outer diameter 50mm, inner diameter 30mm, height 10mm).

[0051] c. Adjustment of vacuum hot pressing sintering process: Since the semi-solid temperature range of aluminum-silicon alloys is approximately 580-620℃, the second stage holding temperature is set to 590℃ for 50 minutes. The final pressure sintering temperature is 640℃, the pressure is 60MPa, and the holding time is 70 minutes. The cooling process is the same as in Example 1.

[0052] The second stage of heat preservation temperature was set at 590℃, which falls within the semi-solid range of the aluminum alloy. Within this range, the base metal possesses both a certain degree of fluidity and a solid skeleton, enabling it to fully fill the voids under pressure and diffuse and fuse with the aluminum shell of the "aluminum-coated" particles, thereby achieving high density and strong interfacial bonding.

[0053] d. Demolding yields the wear-resistant ring blank.

[0054] This embodiment is designed for high-temperature applications. A silicon carbide coating is selected and matched with an aluminum alloy semi-solid sintering window to ensure the chemical stability and interfacial strength of the coating at high temperatures, so that the composite material can achieve high thermal conductivity while also having good heat resistance.

[0055] Tests showed that the wear-resistant ring composite material has a thermal conductivity of 598 W / (m·K) and a flexural strength of 285 MPa at room temperature. After being placed in an air atmosphere at 400℃ for 100 hours, there was no significant degradation at the interface, and the performance retention rate was over 95%, demonstrating excellent high-temperature stability. The inner and outer circular surfaces of the ring are smooth and can be used directly or subjected to minor fine grinding.

[0056] Example 3

[0057] This embodiment uses a silicon coating to prepare a low-stress, precision, near-net-shape heat sink component. The heat sink has high requirements for matching the coefficient of thermal expansion in optoelectronic device packaging.

[0058] S1. Preparation of silicon-coated diamond particles a. Select diamond particles with a diameter of 200 μm, clean and dry them.

[0059] b. Using a physical vapor deposition (PVD) magnetron sputtering system with high-purity silicon as the target, an amorphous silicon coating with a thickness of approximately 0.8 μm was sputtered onto the surface of diamond particles under an argon atmosphere. Process parameters: Base vacuum 5 × 10⁻⁶ -4 Pa, working air pressure 0.8 Pa, sputtering power 800 W, time 30 min.

[0060] c. Post-coating treatment.

[0061] S2. Preparation of aluminum-silicon coated diamond particles The process is the same as in Example 1, with a thickness of approximately 450 μm, using molten pure aluminum for pouring, and a submersion height of approximately 200 μm. After crushing, 30-300 mesh particles are sieved out.

[0062] S3, Net Near-Shape Sintering a. Aluminum-coated granules and aluminum powder are mixed at a volume ratio of 3.5:6.5.

[0063] b. Fill the precision graphite mold to form a complex heat sink part with multiple positioning posts and screw hole steps.

[0064] c. Vacuum hot pressing sintering: The second stage holding temperature is 480℃ (semi-solid range of pure aluminum), held for 60 min. The final sintering temperature is 600℃, the pressure is 40MPa, and the holding time is 80 min. A slower cooling rate (10℃ / min to 200℃) is used to reduce internal stress.

[0065] Using a slower cooling rate helps reduce residual stress caused by the difference in thermal expansion coefficients between the aluminum matrix and diamond particles, thereby improving the dimensional stability and reliability of composite materials, especially complex-shaped components.

[0066] d. Demolding yields the heat sink part.

[0067] By selecting a silicon coating and an optimized low-temperature slow sintering process, the internal stress caused by thermal mismatch is effectively alleviated while ensuring interfacial bonding, thereby obtaining a near-net-shape component with low stress and high dimensional accuracy suitable for optoelectronic device packaging.

[0068] The thermal conductivity of this component is 602 W / (m·K), and its coefficient of thermal expansion (25-125℃) is 7.8 × 10⁻⁶. -6 / K, with good compatibility with common ceramic substrates. The parts have smooth surfaces, clear step shapes for positioning posts and screw holes, and dimensional accuracy that meets assembly requirements. Only a small amount of tapping is required for the screw holes to be used, achieving true near-net-shape forming.

[0069] Comparative Example 1 An attempt was made to prepare a heat dissipation substrate similar to that of Example 1. First, a thin silicon carbide preform (3 mm thick) with a porosity of 35% was prepared, and flow channel grooves were machined onto it. Then, 200 μm Cu-coated diamond particles, similar to those in Example 1, were filled into the grooves, and a silicon carbide cover plate was placed on top to form a composite blank. Vacuum pressure infiltration was performed: the lower chamber (where the blank was placed) temperature was 650°C, the upper chamber (pure aluminum ingot) temperature was 780°C, argon gas was introduced to pressurize to 6 MPa, and the pressure was held for 10 min. After cooling, the composite material was obtained. Its surface is an aluminum silicon carbide layer. Tests revealed that the overall thermal conductivity was 520 W / (m·K), lower than that of Example 1; the surface roughness Ra was 3.5 μm, which is relatively rough; and due to the difficulty in uniformly applying the infiltration pressure to all parts of the complex flow channels, incomplete infiltration (micropores) appeared at the tips of some narrow fins. The surface needs to be machined and polished before it can be used for welding, and the flow channel shape also needs to be adjusted.

[0070] Comparative Example 2 The same Cu-coated diamond particles as in Example 1 were loaded into a simple stainless steel mold and pretreated by spark plasma sintering (800°C, 20 MPa, 5 min). The pretreated particles were then transferred to a graphite mold (without the aluminum coating step) and directly subjected to gas pressure infiltration (process parameters same as Comparative Example 1). The resulting material had acceptable thermal conductivity in the core, but the surface had exposed diamond particles and a roughness Ra greater than 10 μm, making direct joining or conventional machining impossible. Expensive laser or EDM machining was required for shaping, and the surface still needed to be coated with a metal layer after machining.

[0071] The main performance and process characteristics of Examples 1-3 are compared with those of Comparative Examples 1-2, and the results are summarized in the table below.

[0072] Table 1: Comparison of main properties and process characteristics of composite materials prepared in the embodiments of the present invention and the comparative examples.

[0073] As shown in the table above, Examples 1-3 of the present invention are significantly superior to the comparative examples in terms of thermal conductivity, surface quality, and net near-formability. Comparative Example 1 suffers from poor thermal conductivity and surface quality due to limitations in the surface layer material and impregnation process; Comparative Example 2 completely fails to solve the surface processing problem. The present invention successfully combines high performance with good manufacturability through the synergy of "aluminum coating" and "semi-solid sintering".

[0074] In summary, the near-net-shape diamond / aluminum composite material and its preparation method provided by this invention effectively solve the long-standing problems of interface bonding and processing in the field of high thermal conductivity composite materials through innovative process combinations. The prepared material has excellent comprehensive performance and is especially suitable for advanced electronic packaging and thermal management fields with stringent requirements for heat dissipation, reliability and manufacturing cost.

[0075] The above embodiments are merely illustrative of the technical concept and features of the present invention, intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and should not be construed as limiting the scope of protection of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description, and thus all changes falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention.

Claims

1. A method for preparing an aluminum-coated diamond-aluminum composite material, comprising the following steps: S1. Preparation of coated diamond particles: A coating is prepared on the surface of diamond particles, wherein the coating is one of a metallic copper coating, a silicon carbide coating, or a silicon coating. S2. Preparation of aluminum-coated diamond particles: The coated diamond particles obtained in step S1 are spread in a high-temperature mold, and aluminum liquid is poured in to completely immerse them. After cooling, they are crushed and screened to obtain aluminum-coated diamond particles with an outer aluminum layer. S3. Net near-forming sintering: The aluminum-coated diamond particles obtained in step S2 are mixed with aluminum powder and then placed into a mold. The mold is placed in a vacuum hot pressing sintering furnace and pressure is applied within the semi-solid temperature range of aluminum or aluminum alloy for sintering. After cooling and demolding, the net near-forming diamond aluminum composite material is obtained.

2. The method for preparing aluminum-coated diamond-aluminum composite material according to claim 1, characterized in that, In step S1, when the coating is a copper coating, it is prepared by chemical plating; when the coating is a silicon carbide coating, it is prepared by chemical vapor deposition; and when the coating is a silicon coating, it is prepared by physical vapor deposition magnetron sputtering.

3. The method for preparing an aluminum-coated diamond-aluminum composite material according to claim 1, characterized in that, Step S2 specifically includes: (1) The coated diamond particles are laid in a single layer in a high-temperature mold, and the thickness of the layer is 1.0-1.5 times the diameter of the single particle; (2) Heat industrial pure aluminum or aluminum alloy to 700-850℃ to melt it into molten aluminum; (3) Pour the molten aluminum into the mold at a speed of 5-10 mL / s until the molten aluminum covers the surface of the particles by a height of 0.5-1.0 times the particle diameter, and then let it cool naturally to room temperature; (4) The cooled block is crushed and sieved to obtain 20-300 mesh particles, which are aluminum-coated diamond particles.

4. The method for preparing aluminum-coated diamond-aluminum composite material according to claim 1, characterized in that, In step S3, the volume mixing ratio of the aluminum-coated diamond particles to the aluminum powder is 3:(2~7).

5. The method for preparing aluminum-coated diamond-aluminum composite material according to claim 1, characterized in that, In step S3, the process parameters for vacuum hot pressing sintering are: vacuum degree ≤ 5 × 10⁻⁶. -3 Pa; heat to 300-400℃ at a rate of 5-15℃ / min and hold for 20-30min, continue heating to 450-550℃ and hold for 30-60min, then apply a pressure of 30-80MPa at a temperature of 580-650℃ and hold for 40-90min; then cool to below 200℃ at a rate of 10-25℃ / min and cool to room temperature in the furnace.

6. The method for preparing an aluminum-coated diamond-aluminum composite material according to claim 5, characterized in that, The temperature range of 450-550℃ is the semi-solid temperature range for aluminum or aluminum alloy materials.

7. The method for preparing an aluminum-coated diamond-aluminum composite material according to claim 1, characterized in that, In step S3, the mold is a graphite mold customized according to the final shape of the product.

8. An aluminum-coated diamond-aluminum composite material, comprising an aluminum matrix and diamond particles dispersed in the aluminum matrix, characterized in that, The surface of the diamond particles has one of a copper coating, a silicon carbide coating, or a silicon coating, and the outer periphery of the coated diamond particles is also covered with an aluminum layer that is metallurgically bonded to the aluminum matrix; the outer surface of the composite material is a dense aluminum or aluminum alloy layer.

9. The aluminum-coated diamond-aluminum composite material according to claim 8, characterized in that, When the surface of the diamond particles is coated with metallic copper, the coating forms a metallurgical interface with the aluminum substrate; when the surface of the diamond particles is coated with silicon carbide or silicon, the coating reacts with the aluminum substrate to generate a stable intermediate phase interface.

10. An aluminum-coated diamond-aluminum composite material according to claim 8 or 9, characterized in that, The composite material has a thermal conductivity of not less than 590 W / (m·K), a density of not less than 90%, and a surface roughness Ra≤1.6μm, and can be directly brazed and machined using conventional methods.

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