A double-plating modified diamond heat-conducting composite material, a preparation method and application thereof

Abstract

The present application relates to a kind of double plating modified diamond heat-conducting composite material, preparation method and application, steps include first pretreatment diamond particles;First surface treatment process is executed to pretreated diamond particles, and the metal carbide plating layer is formed on the surface of the diamond particles;Second surface treatment process is executed to the diamond particles with metal carbide plating layer, and the electroplated metal layer is formed on the surface of the metal carbide plating layer of diamond particles;Subzone preparation mixed powder and obtain subzone powder with electroplated metal layer of diamond particles are mixed with each subzone powder according to different volume, according to the order of filling layer filling, after filling, sintering is formed, to make modified diamond heat-conducting composite material.The present application generates nanoscale metal carbide plating layer TiC layer and Cr3C2 layer by magnetron sputtering on the surface of diamond, which forms covalent bond with diamond, and the interface bonding strength is significantly improved compared with uncoated layer.

Description

Technical Field

[0001] This invention relates to the field of metal composite material processing, and more particularly to a double-coated modified diamond thermally conductive composite material, its preparation method, and its application. Background Technology

[0002] With the rapid development of microelectronic devices towards higher integration and higher power density, the thermal conductivity of traditional heat dissipation materials (such as pure copper and aluminum-based composites) is no longer sufficient to meet the heat dissipation requirements of next-generation chips. Diamond, due to its ultra-high thermal conductivity and low coefficient of thermal expansion, is considered an ideal reinforcing phase material. Diamond composites, by combining the thermal conductivity advantages of diamond with the processing properties of metals, have become a key material for solving the heat dissipation bottleneck of high-power devices. However, problems such as poor interfacial compatibility between diamond and the metal matrix, and thermal expansion mismatch, result in the actual thermal conductivity of composite materials being far lower than the theoretical value, severely restricting their industrial application.

[0003] Currently, research on diamond materials mainly focuses on improving the surface metallization of diamond and alloying the metal matrix. Improving the surface metallization of diamond requires depositing a metal layer on the diamond surface through chemical plating, which can lead to poor coating uniformity, i.e., low interfacial bonding strength. This is mainly manifested in the weak bonding between diamond and Cu metal, which is prone to debonding. On the other hand, if the melt infiltration method is used, it will lead to the graphitization of diamond, and the equipment cost is high.

[0004] Furthermore, metal matrix alloying involves adding active elements to the Cu metal matrix to generate a carbide layer through interfacial reaction. However, the carbide layer is uncontrollable, and excessive reaction can easily damage the diamond surface. Moreover, promoting interfacial bonding through high-temperature hot pressing is a complex and energy-intensive process, making it difficult to manufacture large-size components. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a double-coated modified diamond thermally conductive composite material, its preparation method and application, so as to solve one or more problems in the prior art.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A method for preparing a double-coated modified diamond thermally conductive composite material, characterized by the following steps:

[0008] First pretreatment of diamond particles;

[0009] The pretreated diamond particles are subjected to a first surface treatment process to form a metal carbide coating on the surface of the diamond particles.

[0010] A second surface treatment process is performed on the diamond particles that form the metal carbide coating to form an electroplated metal layer on the surface of the metal carbide coating of the diamond particles.

[0011] Prepare mixed powder by partitioning and obtain partitioned powder;

[0012] Diamond particles with electroplated metal layers are mixed with powders of different volumes in different zones, and then filled in layers according to the filling sequence. After filling, the mixture is sintered to form a modified diamond thermally conductive composite material.

[0013] The first surface treatment process includes the following steps:

[0014] Install the target material and adjust the target base distance;

[0015] Evacuate the vacuum and introduce high-purity argon gas;

[0016] Turn on the power supply, select the DC magnetron sputtering mode, and first magnetron sputter the diamond particles to deposit Ti. After the Ti magnetron sputtering is completed, magnetron sputter the Cr particles to deposit Cr. The Ti magnetron sputtering time is 40-60 minutes and the power of the Ti magnetron sputtering is 120-180W. The Cr magnetron sputtering time is 50-70 minutes and the power of the Cr magnetron sputtering is 120-180W.

[0017] After magnetron sputtering Cr, the diamond particles with the metal carbide coating are cooled to below 100°C in a vacuum environment, the argon gas supply is stopped, the vent valve is opened, and the diamond particles with the metal carbide coating are removed after the table surface temperature has cooled to room temperature.

[0018] The second surface treatment process includes the following steps:

[0019] Plating solution preparation; second pretreatment of diamond particles for forming metal carbide coatings;

[0020] Diamond particles are mounted and immersed in a plating solution and then subjected to conductive treatment, wherein the current density is 1–3 A / dm³. 2 The temperature is 45-55℃ and the time is 20-50 minutes. The electroplated diamond particles are ultrasonically washed with deionized water for 5-7 minutes and dried at 100-120℃ for 2-3 hours. After drying, they are annealed at 300-400℃ for 30 minutes to form an electroplated metal layer on the surface of the diamond particles.

[0021] The preparation of the mixed powder by partitioning includes the following steps:

[0022] 94 wt% Cu powder and 6 wt% Mo powder are added to a ball mill and mixed at a speed of 300-400 rpm for 4-5 hours to form a first-zone powder; the first-zone powder accounts for 20% of the total thickness of the zone powder.

[0023] 96 wt% Cu powder and 4 wt% Mo powder are added to a ball mill and mixed at a speed of 300-400 rpm for 3-4 hours to form a second-zone powder; the second-zone powder accounts for 30% of the total thickness of the zone powder.

[0024] 99wt% Cu powder and 1wt% Mo powder are added to a ball mill and mixed at a speed of 300-400 rpm for 2-3 hours to form a third-zone powder; the third-zone powder accounts for 50% of the total thickness of the zone powder.

[0025] The first partition powder is mixed with 40% diamond particles by volume to form a first partition mixture; the second partition powder is mixed with 30% diamond particles by volume to form a second partition mixture; and the third partition powder is mixed with 30% diamond particles by volume to form a third partition mixture.

[0026] The layered filling includes the following steps:

[0027] The third-section mixture is first loaded into the vacuum sintering furnace, so that the third-section mixture is located at the bottom of the vacuum sintering furnace, and the third-section mixture is gently pressed flat with a pressure of 0.5 to 0.6 MPa.

[0028] The second partitioned mixture is loaded into the vacuum sintering furnace a second time, so that the second partitioned mixture is located in the middle of the vacuum sintering furnace, and the first partitioned mixture is gently pressed flat with a pressure of 0.5 to 0.6 MPa.

[0029] The first partition mixture is loaded into the vacuum sintering furnace for the third time, so that the first partition mixture is located at the top of the vacuum sintering furnace, and the first partition mixture is gently pressed flat with a pressure of 0.5 to 0.6 MPa.

[0030] The sintering process includes the following steps:

[0031] One heating step: The temperature of the vacuum sintering furnace is raised from room temperature to 600-650℃, with a heating rate of 10℃±5℃ / min.

[0032] Secondary heating: The temperature is increased from 600-650℃ to 800-850℃ at a rate of 5℃ / min;

[0033] One heat preservation: keep warm at 800~850℃ for 30±10min;

[0034] Three heating cycles: After holding the temperature, the temperature is raised from 800-850℃ to 1000-1050℃, with a heating rate of 3℃±5℃ / min;

[0035] Secondary insulation: Insulate at 1000~1050℃ for 2±1h.

[0036] Remove the modified diamond thermally conductive composite material and treat it with a 5-10T pulsed magnetic field for 10-30 minutes.

[0037] A diamond thermally conductive composite material prepared by a double-layer modified diamond thermally conductive composite material preparation method is disclosed. The diamond thermally conductive composite material consists of a core reinforcing phase, a metal matrix, and an interface modification structure dispersed in the metal matrix. The metal matrix includes a main matrix and a doped metal. The interface modification structure includes a magnetron sputtered metal carbide layer and an electroplated metal layer from the inside out. The thickness of the diamond thermally conductive composite material is 1-10 mm, the particle size of the diamond thermally conductive composite material is 50-200 µm, the thermal conductivity of the diamond thermally conductive composite material is 510-560 W / mK, and the coefficient of thermal expansion is 5-7 ppm / K. The metal matrix is ​​copper, and the doped metal is any one of molybdenum, titanium, or chromium.

[0038] The diamond thermally conductive composite material is used as a packaging material for high-power devices.

[0039] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0040] This invention utilizes magnetron sputtering to deposit nanoscale metal carbide coatings, TiC and Cr3C2, onto the surface of diamond. These coatings form covalent bonds with the diamond, resulting in a significantly improved interfacial bonding strength compared to the uncoated surface.

[0041] By adding an electroplating step, an electroplated metal layer is formed on the outer surface of the metal carbide coating, which can act as a thermal bridge to effectively reduce interfacial thermal resistance and thus improve thermal conductivity.

[0042] By adding vector Mo powder to Cu, a uniformly distributed mixed metal matrix is ​​obtained, which allows the diamond interface to react and generate carbides, thereby improving the interfacial bonding strength and thermal conductivity.

[0043] Layered loading enhances interfacial reaction and increases the density of thermal conductivity pathways. Furthermore, layering maintains matrix shape and reduces costs. Staged temperature-controlled sintering promotes the directional diffusion of Mo from the bottom to the surface, forming a continuous Mo2C interfacial layer. This effectively increases the adhesion between diamond particles and the copper matrix by 3-4 times, reduces the interfacial thermal resistance of the composite material, and thus improves its thermal conductivity. Moreover, this method solves the problem of poor wetting between the Cu metal and diamond, avoiding debonding and weak bonding during composite formation, and effectively improving bonding strength. Attached Figure Description

[0044] Figure 1The illustration shows a dual-coated modified diamond thermally conductive composite material, its preparation method, and a scanning electron microscope image of the diamond with dual coatings in application, according to an embodiment of the present invention.

[0045] Figure 2 The image shows a scanning electron microscope (SEM) image of a double-coated modified diamond thermally conductive composite material, its preparation method, and its application according to an embodiment of the present invention. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a further detailed explanation of the double-coated modified diamond thermally conductive composite material, its preparation method, and its application. The advantages and features of this invention will become clearer from the following description. It should be noted that the accompanying drawings are in a very simplified form and use non-precise proportions, used only to facilitate and clearly illustrate the purpose of the embodiments of this invention. Please refer to the accompanying drawings to make the objectives, features, and advantages of this invention more apparent and understandable. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only for illustrative purposes to aid those skilled in the art and are not intended to limit the implementation conditions of this invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by this invention, should still fall within the scope of the technical content disclosed in this invention.

[0047] Example 1:

[0048] A method for preparing a double-coated modified diamond thermally conductive composite material includes the following steps:

[0049] S1: First pretreatment of diamond particles; diamond particles with a particle size of 50-200µm are selected. Specifically, in this Example 1, diamond particles with a particle size of 50µm are selected. The diamond particles are ultrasonically cleaned in a 5% HNO3 solution for 30 minutes. The purpose of acid washing is to remove surface oxides and impurities of the diamond particles. After acid washing, the particles are taken out and rinsed with deionized water until neutral. They are then vacuum dried at 50°C for 1 hour, thereby making the surface of the diamond particles clean.

[0050] S2: Perform a first surface treatment process on the pretreated diamond particles to form a metal carbide coating on the surface of the diamond particles;

[0051] S200: Vacuum magnetron sputtering equipment is used. First, Ti and Cr targets with a purity greater than 99.9% are installed on the magnetron target. The target-substrate distance between the diamond particles and the Ti and Cr targets is adjusted to 50mm.

[0052] S201: Cover the vacuum chamber of the vacuum magnetron sputtering equipment, evacuate the vacuum, and introduce high-purity argon gas.

[0053] S202: Power on, select DC magnetron sputtering mode, and first magnetron sputter to deposit Ti onto diamond particles. After Ti deposition, magnetron sputter to deposit Cr. The Ti deposition time is 40 minutes, and the power is 120W. During magnetron sputtering, high-energy argon ions bombard the target, and the sputtered Ti atoms are deposited on the diamond surface, reacting with the carbon atoms of the diamond to form a TiC layer (titanium carbide). This TiC layer is covalently bonded to the diamond, significantly improving the interfacial bonding strength. The Cr deposition time is 50 minutes, and the power is 120W. Based on the TiC layer, high-energy argon ions bombard the target material, and the sputtered Cr atoms react with free carbon on the diamond surface or residual carbon in TiC to generate a Cr3C2 layer (chromium carbide). This Cr3C2 is a continuous nanocrystalline composite structure, which can effectively improve thermal conductivity. Furthermore, by combining with TiC to form a double coating, the bonding strength between diamond particles and the substrate is increased by 3 to 4 times. The scanning electron microscope image of this diamond with the double coating is shown below. Figure 1 As shown.

[0054] S203: After magnetron sputtering Cr, the diamond particles are cooled to below 100°C in a vacuum environment, the argon gas supply is stopped, the vent valve is opened, and the diamond particles with a double metal carbide coating (i.e., containing a TiC layer and a Cr3C2 layer) are taken out after the table temperature has cooled to room temperature. This double metal carbide coating can reduce phonon scattering, increase the thermal conductivity from 300W / mK to ≥420W / mK, and increase the bonding strength between the diamond particles and the substrate by 3-4 times.

[0055] S3: Perform a second surface treatment process on the diamond particles that form the double-layer metal carbide coating to form an electroplated metal layer on the surface of the double-layer metal carbide coating of the diamond particles.

[0056] S300: Plating solution preparation; second pretreatment of diamond particles for forming a metal carbide coating; wherein the plating solution preparation includes the following steps:

[0057] S3001: Dissolve nickel sulfate and nickel chloride in deionized water at 60°C and stir until completely dissolved.

[0058] S3002: Add boric acid and stir continuously until transparent.

[0059] S3003: After cooling to room temperature, add 1-3 mL / L of brightener and bring the volume to the target volume. In this embodiment, the brightener can be sodium saccharin.

[0060] S3004: Adjust the pH value of the plating solution to 4.0-4.5.

[0061] The second preprocessing includes the following steps:

[0062] S3100: Diamond particles with a double-layer metal carbide coating are immersed in a 0.1% sodium dodecyl sulfate solution and ultrasonically treated for 10 minutes to improve their surface wettability.

[0063] S3101: Immerse in 5% dilute sulfuric acid for 1 minute to remove the surface oxide film and expose the active TiC and Cr3C2 layers.

[0064] S3102: Rinse the diamond particles with deionized water to ensure no residual acid, and then vacuum dry at 80°C for 1 hour.

[0065] S301: Diamond particles with a double-layer metal carbide coating are loaded into a titanium basket as the cathode to ensure uniform particle dispersion, and a nickel plate is used as the anode.

[0066] S302: Place the cathode and anode separately in the plating solution, where the current density is 1–3 A / dm³. 2 The preferred current density is 1.5 A / dm³. 2 The temperature is 45–55℃, preferably 45℃, and the time is 20–50 min, preferably 25 min. A low current density of 1 A / dm² can be used in the initial stage. 2 After maintaining this state for 5 minutes, a dense sublayer is formed, and then the concentration is gradually increased to 1.5 A / dm. 2 This avoids stress cracking in the coating. Simultaneously, by adding a brightener to the plating bath, it can adsorb onto grain growth sites, inhibiting dendrite formation and refining the grains.

[0067] S303: The electroplated diamond particles are ultrasonically washed with deionized water for 5-7 minutes and dried at 100-120℃ for 2-3 hours. After drying, they are annealed at 300-400℃ for 30 minutes to form an electroplated metal layer on the surface of the diamond particles. The electroplated metal layer is specifically a nanocrystalline nickel layer with a thickness of 1.5-5 μm, a bonding strength of 35-40 MPa, a porosity of <0.5%, and a thermal conductivity contribution of 510-530 W / mK.

[0068] S4: Prepare mixed powder by partitioning and obtain partitioned powder.

[0069] S401: Add 94 wt% Cu powder and 6 wt% Mo powder to a ball mill and mix them. The ball mill rotates at 300-400 rpm and the mixing time is 4-5 hours to form a first partition powder. The first partition powder accounts for 20% of the total partition powder thickness.

[0070] S402: Add 96wt% Cu powder and 4wt% Mo powder to a ball mill and mix them. The ball mill rotates at 300-400 rpm and the mixing time is 3-4 hours to form a second partition powder. The second partition powder accounts for 30% of the total partition powder thickness.

[0071] S403: Add 99wt% Cu powder and 1wt% Mo powder to a ball mill and mix them. The ball mill rotates at 300-400 rpm and the mixing time is 2-3 hours to form a third-zone powder. The third-zone powder accounts for 50% of the total thickness of the zone powder.

[0072] S5: Diamond particles with electroplated metal layers are mixed with powder from each zone according to different volumes. Specifically, the powder from the first zone is mixed with diamond particles with a volume fraction of 40% to 50% to form a first zone mixture; the powder from the second zone is mixed with diamond particles with a volume fraction of 30% to 40% to form a second zone mixture; and the powder from the third zone is mixed with diamond particles with a volume fraction of 20% to 30% to form a third zone mixture.

[0073] S6: The first partition mixture, the second partition mixture, and the third partition mixture are filled in layers according to the filling order. The layer filling includes the following steps:

[0074] S600: The third-zone mixture is first loaded into the vacuum sintering furnace, so that the third-zone mixture is located at the bottom of the vacuum sintering furnace, and the third-zone mixture is gently pressed flat with a pressure of 0.5 to 0.6 MPa.

[0075] S601: The second partition mixture is loaded into the vacuum sintering furnace for the second time, so that the second partition mixture is located in the middle of the vacuum sintering furnace, and the second partition mixture is gently pressed flat with a pressure of 0.5 to 0.6 MPa.

[0076] S602: The first partition mixture is loaded into the vacuum sintering furnace for the third time, so that the first partition mixture is located at the top of the vacuum sintering furnace, and the first partition mixture is gently pressed flat with a pressure of 0.5 to 0.6 MPa.

[0077] The above-mentioned layer-by-layer partitioned mixture is lightly pressed after filling, thereby eliminating gaps and making it less prone to cracking during sintering.

[0078] S7: The mixed powder from each zone, after being filled, is subjected to gradient sintering. The sintering process is as follows:

[0079] S700: Single heating: The temperature of the vacuum sintering furnace is raised from room temperature to 600-650℃ at a rate of 10℃±5℃ / min. During this process, the high content of Mo reacts with diamond to form a continuous Mo2C layer.

[0080] Secondary heating: The temperature is increased from 600℃ to 850℃ at a rate of 5℃ / min. During this process, a high concentration of Mo diffuses to the diamond surface and reacts with the diamond to form a localized Mo2C layer.

[0081] First heat preservation: Hold at 800℃ for 30 minutes. During this first heat preservation stage, the temperature deviation must be ≤±5℃ and the time error ≤2 minutes; otherwise, Mo diffusion will be excessive or insufficient. In this stage, Cu is in a solid state, and Mo migrates through solid-phase diffusion. The diffusion coefficient of Mo in solid Cu is (D≈1×10⁻⁶). -14 m 2 The concentration of Mo per second ( / s) is sufficient to achieve surface enrichment, but not enough to achieve complete homogenization. Furthermore, the surface Mo content and the low Mo content in the core form a concentration gradient, driving Mo atoms to migrate to the surface, thereby achieving directional migration of Mo.

[0082] Three heating cycles: After holding the temperature, the temperature is increased from 800℃ to 1000℃, with a heating rate of 3℃±5℃ / min.

[0083] Secondary heat preservation: The temperature is maintained at 1000℃ for 2±1h. During the high heat preservation process, the heating rate should be controlled at ≤±5℃. Too fast a rate will lead to uneven flow of liquid Cu. After the heat preservation is completed, liquid Cu accelerates the local diffusion of Mo, but the overall gradient distribution is preserved. Compared with conventional designs without gradient and without heat preservation temperature, this application can further achieve the preset concentration distribution of Mo, optimize the diffusion path of Mo, enhance the interfacial reaction, improve the gradient transition of the coefficient of thermal expansion, and reduce residual stress.

[0084] Scanning electron microscope image of diamond thermally conductive composite material as shown below Figure 2 As shown, by performing layered packing before sintering, the surface layer is enriched with Mo and the Mo2C layer is made continuous, reducing the interfacial thermal resistance. The low Mo content at the bottom reduces the formation of brittle phases. During sintering, the Mo2C layer forms a gradient interfacial layer through directional diffusion of Mo and reaction with diamond. Due to the gradient Mo diffusion, the interfacial Mo2C layer exhibits a nanocrystalline / amorphous composite structure. The amorphous region can fill the grain boundaries and inhibit crack propagation, while the nanocrystalline region can provide high hardness.

[0085] Furthermore, the interfacial bonding strength of the aforementioned Mo2C layer can reach 147–163 MPa, the flexural strength can reach 180–200 MPa, the thermal conductivity can reach 510–560 W / mK, and the coefficient of thermal expansion can reach 5–7 ppm / K.

[0086] Furthermore, after the above sintering steps are completed, the modified diamond thermally conductive composite material is subjected to a 5-10T pulsed magnetic field for 10-30 minutes. This step can utilize the magnetic field to induce interfacial dislocation rearrangement, reduce residual stress, and further improve thermal conductivity.

[0087] Example 2

[0088] The difference between Example 2 and Example 1 lies in the first surface treatment process performed on the pretreated diamond particles. In Example 1, Ti was deposited by magnetron sputtering first, followed by Cr. In Example 2, Cr was deposited by magnetron sputtering first, followed by Ti. Furthermore, in the electroplating process, a Ni layer was plated in Example 1, while a Cu layer was plated in this example. Additionally, when the cathode and anode were immersed in the plating bath, the current density was increased to 3 A / dm³. 2 This accelerates the Cu deposition rate and lowers the plating bath temperature to 25–35°C, effectively preventing Cu oxidation.

[0089] The electroplating process for preparing mixed powder in sections, layered filling, and sintering is the same as in Example 1. The gradient interface layer formed after sintering includes a composite layer of Mo2C and Cr3C2 and a Ti-Cu solid solution. The gradient interface layer contains trace amounts of Mo reacting with TiC on the diamond surface to form a MO-TI-C ternary compound.

[0090] Specifically, the gradient interface layer has an interface strength of 135±10MPa, a thermal conductivity of 560±8W / mK, a coefficient of thermal expansion of 6.0±0.3 ppm / K, and a bending strength of up to 100%. With further improvements in its thermal conductivity, it can effectively adapt to ultra-high power heat dissipation scenarios, reduce the thermal stress of the package, and replace electroplated Ni with electroplated Cu, thus significantly reducing costs.

[0091] Comparative Example 1 does not include the steps of preparing mixed powder in sections and mixing the sectioned powder with diamond particles of different volumes having electroplated metal layers; the remaining steps are the same as in Example 1.

[0092] Specifically, the technical effects of the aforementioned gradient interface layer are presented in a table below:

[0093]

[0094] As can be seen from the above, gradient layering design can optimize the coefficient of thermal expansion and interfacial bonding strength, while improving thermal conductivity and flexural strength. The double-coating design can solve the problem of insufficient bonding strength of a single interfacial layer, thereby improving the reliability and thermal conductivity of the material.

[0095] The diamond thermally conductive composite material prepared using the above-mentioned method for preparing a double-layer modified diamond thermally conductive composite material comprises a core reinforcing phase, a metal matrix, and an interface-modified structure dispersed in the metal matrix. The core reinforcing phase is composed of diamond particles. The metal matrix includes a main matrix and a doped metal. The interface-modified structure, from the inside out, includes a Mo2C reaction layer, an electroplated metal layer, and a magnetron sputtered metal carbide layer. The thickness of the diamond thermally conductive composite material is 1–10 mm, the particle size of the diamond thermally conductive composite material is 50–200 µm, the thermal conductivity of the diamond thermally conductive composite material is 510–560 W / mK, and the coefficient of thermal expansion is 5–7 ppm / K. The main matrix is ​​copper, and the doped metal is either molybdenum or titanium.

[0096] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0097] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a double-coated modified diamond thermally conductive composite material, characterized in that... The steps include the following: First pretreatment of diamond particles; The diamond particles that have undergone the first pretreatment are subjected to a first surface treatment process to form a metal carbide coating on the surface of the diamond particles. A second surface treatment process is performed on the diamond particles that form a metal carbide coating, so that an electroplated metal layer is formed on the surface of the metal carbide coating of the diamond particles. The process involves preparing a mixed powder by partitioning the powder and obtaining the partitioned powder; the preparation of the mixed powder by partitioning includes the following steps: 94 wt% Cu powder and 6 wt% Mo powder are added to a ball mill and mixed at a speed of 300-400 rpm for 4-5 hours to form a first-zone powder; the first-zone powder accounts for 20% of the total thickness of the zone powder. 96 wt% Cu powder and 4 wt% Mo powder are added to a ball mill and mixed at a speed of 300-400 rpm for 3-4 hours to form a second-zone powder; the second-zone powder accounts for 30% of the total thickness of the zone powder. 99wt% Cu powder and 1wt% Mo powder are added to a ball mill and mixed at a speed of 300-400 rpm for 2-3 hours to form a third-zone powder; the third-zone powder accounts for 50% of the total thickness of the total zone powder. Diamond particles with electroplated metal layers are mixed with powders of different volumes in each zone. Specifically, the powder of the first zone is mixed with 40% diamond particles by volume to form a first zone mixture; the powder of the second zone is mixed with 30% diamond particles by volume to form a second zone mixture; and the powder of the third zone is mixed with 30% diamond particles by volume to form a third zone mixture. The filling is carried out in layers according to the filling sequence, and the layered filling includes the following steps: The third-section mixture is first loaded into the vacuum sintering furnace, so that the third-section mixture is located at the bottom of the vacuum sintering furnace, and the third-section mixture is gently pressed flat with a pressure of 0.5 to 0.6 MPa. The second section of the mixture is loaded into the vacuum sintering furnace a second time, so that the second section of the mixture is located in the middle of the vacuum sintering furnace, and the second section of the mixture is gently pressed flat with a pressure of 0.5 to 0.6 MPa. The first partition mixture is loaded into the vacuum sintering furnace for the third time, so that the first partition mixture is located at the top of the vacuum sintering furnace, and the first partition mixture is gently pressed flat with a pressure of 0.5 to 0.6 MPa. After filling, it is sintered to form a modified diamond thermally conductive composite material.

2. The method for preparing a double-coated modified diamond thermally conductive composite material as described in claim 1, characterized in that: The first surface treatment process includes the following steps: Install the target material and adjust the target base distance; Evacuate the vacuum and introduce high-purity argon gas; Turn on the power supply, select the DC magnetron sputtering mode, and first magnetron sputter the diamond particles to deposit Ti. After the Ti magnetron sputtering is completed, magnetron sputter the Cr particles to deposit Cr. The Ti magnetron sputtering time is 40-60 minutes and the power of the Ti magnetron sputtering is 120-180W. The Cr magnetron sputtering time is 50-70 minutes and the power of the Cr magnetron sputtering is 120-180W. After magnetron sputtering Cr, the diamond particles with the metal carbide coating are cooled to below 100°C in a vacuum environment, the argon gas supply is stopped, the vent valve is opened, and the diamond particles with the metal carbide coating are removed after the table surface temperature has cooled to room temperature.

3. The method for preparing a double-coated modified diamond thermally conductive composite material as described in claim 1, characterized in that: The second surface treatment process includes the following steps: Plating solution preparation; second pretreatment of diamond particles for forming metal carbide coatings; Diamond particles are mounted and immersed in a plating solution and then subjected to conductive treatment, wherein the current density is 1–3 A / dm³. 2 The temperature is 45-55℃ and the time is 20-50 minutes. The electroplated diamond particles are ultrasonically washed with deionized water for 5-7 minutes and dried at 100-120℃ for 2-3 hours. After drying, they are annealed at 300-400℃ for 30 minutes to form an electroplated metal layer on the surface of the diamond particles.

4. The method for preparing a double-coated modified diamond thermally conductive composite material as described in claim 1, characterized in that: Remove the modified diamond thermally conductive composite material and treat it with a 5-10T pulsed magnetic field for 10-30 minutes.

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