Etching diamond copper composite material containing Mo2C transition layer and preparation method thereof

Abstract

The invention belongs to the technical field of metal-based composite materials, and particularly relates to an etched diamond copper composite material containing a Mo2C transition layer and a preparation method of the etched diamond copper composite material. According to the material, muffle furnace etching is carried out on the surfaces of diamond particles to form regular triangular and rectangular micro-pit structures so as to improve the surface roughness and the specific surface area, and then a nanoscale Mo2C transition layer is generated on the etched diamond surface through a molten salt method. The micro-pit structure obviously enhances the mechanical embedding of the diamond and the copper substrate, and the Mo2C layer realizes a continuous heat conduction channel with low interface thermal resistance through chemical bonding. According to the method, the wettability and bonding strength between diamond and copper are effectively improved, and the thermal conductivity of the composite material reaches 706 W.m <-1 >. K <-1 > under the condition that the volume fraction of diamond is 50 vol% and is improved by about 6.3% compared with that of an unetched sample. The method is simple in process, low in cost, capable of achieving batch preparation and suitable for the field of heat dissipation and packaging of high-power electronic devices.

Description

Technical Field

[0001] This invention belongs to the field of metal matrix composite technology, specifically relating to an etched diamond copper composite material containing a Mo2C transition layer and its preparation method, which is suitable for high thermal conductivity, high reliability electronic packaging and heat dissipation applications. Background Technology

[0002] As electronic devices continue to miniaturize and power density continues to rise, the heat generated by chips and power modules increases significantly. Traditional copper-based heat dissipation materials exhibit problems such as insufficient heat dissipation capacity and decreased reliability in high heat flux density scenarios, highlighting the urgent need for new thermal management materials that combine high thermal conductivity with scalable manufacturing capabilities.

[0003] Diamond / copper (D / Cu) composites combine the ultra-high intrinsic thermal conductivity of diamond with the excellent processability of copper, and are considered to be the next generation of high-performance heat dissipation substrates. However, due to the poor wettability of the diamond / copper interface, weak interfacial bonding, and large interfacial thermal resistance caused by phonon mismatch, cross-interfacial phonon transport is limited, resulting in a significant gap between the actual thermal conductivity of the composite and the theoretical expectations.

[0004] Existing technologies mostly use metallization or coating transition layers (such as Ti, Cr, Zr, Mo, etc.) to improve the interface. Among them, the scheme of forming a metal carbide layer by Mo has better overall performance, but single metallization modification still has problems such as complex process, narrow window and limited improvement in thermal conductivity.

[0005] Therefore, there is a lack of a heat dissipation substrate preparation process that is simple in process, uses universal equipment, is easy to scale up, and can achieve competitive thermal conductivity. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies in terms of cost, interface wetting and bonding, and process complexity, this invention provides a diamond-copper composite material and its preparation method that synergistically constructs interfacial thermal channels through crystal orientation selective etching and a Mo2C transition layer. Compared to processes relying on high pressure or complex procedures (such as SPS discharge plasma sintering and pressure-assisted liquid metal infiltration), this invention introduces a synergistic strategy of "etching + Mo2C transition layer" under conventional vacuum hot pressing conditions. On the one hand, crystal orientation selective micropits enhance mechanical interlocking and the actual contact area; on the other hand, a continuous Mo2C layer constructs a stable heat conduction bridge. This achieves competitive thermal conductivity and a reproducible process window while ensuring process simplicity, equipment versatility, and scalability. This invention achieves a balance of high thermal conductivity, strong interfacial bonding, and low porosity under conventional vacuum hot pressing conditions while maintaining process simplicity and equipment versatility, making it suitable for high heat flux density electronic packaging and heat dissipation scenarios.

[0007] To achieve the above objectives, the present invention provides the following technical solution: An etched diamond-copper composite material containing a Mo2C transition layer, the composite material comprising a copper matrix and diamond particles dispersed in the copper matrix; the diamond particles are etched to form a micropit structure on the surface of the copper matrix; the surface of the diamond particles is coated with a nanoscale Mo2C transition layer generated in situ by molten salt reaction, and a Cu / Mo2C / diamond three-layer interface structure is formed between the diamond particles and the copper matrix; wherein the copper matrix at least partially fills the micropit structure to form mechanical intercalation and reduce interface defects.

[0008] Furthermore, the crystal facets of the diamond particles include a (100) facet and a (111) facet, wherein the (100) facet forms a rectangular etching pit and the (111) facet forms a triangular etching pit; the depth of the micropit is 0.2 to 1.4 μm.

[0009] Furthermore, the surface roughness Sa of the diamond particles is 20–90 nm; the BET specific surface area of ​​the etched diamond particles is not less than 0.014 m². 2 ·g -1 .

[0010] Furthermore, the diamond volume fraction is 30–60 vol%, and the thermal conductivity of the composite material is ≥ 700 W·m. -1 ·K -1 .

[0011] The present invention also discloses a method for preparing the composite material, comprising the following steps: Step 1: Cleaning and drying of diamond particles; Step 2: Use a muffle furnace to oxidize and etch diamond particles in an oxygen-containing atmosphere to form a micro-pit structure on their surface; Step 3: The etched diamond particles are reacted with a molybdenum source under vacuum in a NaCl and KCl molten salt environment to generate a Mo2C transition layer in situ on the diamond surface. The diamond is then cleaned, desalted, and dried. Step 4: Anneal and reduce the copper powder in a hydrogen atmosphere; Step 5: Mix copper powder with Mo2C-coated diamond particles and then vacuum hot-press sinter to form the shape.

[0012] Furthermore, in step two, the temperature of the muffle furnace is 600–800℃, and the holding time is 20–60 min.

[0013] Furthermore, in step three, the mass ratio of NaCl to KCl is 1:1, and the vacuum degree is 1×10⁻⁶. -3 Pa, heating rate 3-5℃ / min, heat to 1100℃ and hold for 30 min.

[0014] Furthermore, in step four, the copper powder is annealed and reduced at 500°C under an H2 atmosphere.

[0015] Furthermore, in step five, the volume fraction of diamond is 30–60 vol.

[0016] Furthermore, the composite material is used in electronic packaging heat dissipation substrates, power device heat dissipation base plates, or high heat flux density heat dissipation components.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention constructs a crystal orientation-selective micropit structure on the diamond surface through oxygen etching at 700℃ for 30 min in a muffle furnace—triangular pits on the (111) facet and rectangular pits on the (100) facet—significantly improving the surface roughness and specific surface area of ​​the particles. Subsequently, it reacts with molybdenum at 1100℃ for 30 min in a NaCl / KCl molten salt environment to generate a dense and continuous Mo2C transition layer in situ on the diamond surface. This layer is then densified with copper powder under vacuum hot pressing to construct a Cu–Mo2C–Diamond continuous interface. This synergistic strategy, on the one hand, promotes the infiltration of the copper phase into the micropits and forms mechanical interlocking at the physical level, reducing interface defects and particle pull-out; on the other hand, it stabilizes the heat transfer channel through the metallurgical bonding of Mo2C with diamond / copper at the chemical level, thereby achieving a unity of strong interfacial bonding and efficient cross-interfacial heat transfer.

[0018] This invention features a simple process, universal equipment, and ease of scalability: the entire process can be completed with only a muffle furnace, a tube furnace, and vacuum hot pressing equipment, avoiding high-pressure or complex discharge plasma processes, thus offering significant engineering and cost advantages. Taking a 50 vol% diamond volume fraction as an example, the measured thermal conductivity of the resulting composite material is 706 W·m. -1 ·K -1 Compared to the unetched control sample, 664 W·m -1 ·K -1 Significantly improved, suitable for high heat flux density electronic packaging substrates, power device heat dissipation base plates, RF / power amplifier heat dissipation modules and laser heat dissipation components and other scenarios. Attached Figure Description

[0019] Figure 1 This is an optical microscopic image of the different crystal planes of diamond particles before and after etching in this invention.

[0020] Figure 2 This is an optical micrograph of the surface morphology of diamond particles etched at 500℃ in Embodiment 1 of the present invention.

[0021] Figure 3This is an optical micrograph of the surface morphology of diamond particles etched at 700℃ in Embodiment 1 of the present invention.

[0022] Figure 4 This is an optical micrograph of the surface morphology of diamond particles etched at 900℃ in Embodiment 1 of the present invention.

[0023] Figure 5 This is a comparison of the Raman spectra of diamond particles before and after etching in this invention.

[0024] Figure 6 These are atomic force microscopy (AFM) two-dimensional and three-dimensional morphology images of the diamond particle surface before and after etching in this invention.

[0025] Figure 7 The figures show the nitrogen adsorption isotherms and BET specific surface area analysis of diamond particles before and after etching in this invention.

[0026] Figure 8 To compare the surface SEM morphology and carbonization layer thickness of the unetched M3 sample in Case 3 after molten salt treatment.

[0027] Figure 9 This is a SEM image of the surface morphology and carbonization layer thickness of the etched N3 sample after molten salt treatment in this invention.

[0028] Figure 10 The images show the cross-sectional SEM microstructure of the diamond-copper composite material prepared from the M3 sample (unetched) and the N3 sample (etched) in this invention.

[0029] Figure 11 The images show a comparison of the SEM morphology of the composite material cross-sections under different diamond volume fractions (30 vol%, 40 vol%, 60 vol%) in the implementation examples and comparative examples of this invention.

[0030] Figure 12 This is a comparison chart of the thermal conductivity and density properties of etched and unetched samples of the present invention at different diamond volume fractions.

[0031] Figure 13 This is a graph showing the trend of thermal conductivity variation of a 50 vol% etched sample at different test temperatures in this invention. Detailed Implementation

[0032] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0033] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0034] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0035] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0036] This invention discloses an etchable diamond-copper composite material containing a Mo2C transition layer, comprising a copper matrix and diamond particles dispersed in the copper matrix; the diamond particles are etched to form a micropit structure on the surface of the copper matrix; the surface of the diamond particles is coated with a nanoscale Mo2C transition layer generated in situ by molten salt reaction, forming a Cu / Mo2C / diamond three-layer interface structure between the diamond particles and the copper matrix; wherein the copper matrix at least partially fills the micropit structure to form mechanical intercalation and reduce interface defects. The crystal planes of the diamond particles include (100) planes and (111) planes. Figure 1 (a) is the (111) surface before etching, (b) is the (111) surface after etching forming a triangular etching pit, (c) is the (100) surface before etching, and (d) is the (100) surface after etching forming a rectangular etching pit.

[0037] The depth of the micro-pit is 0.2–1.4 μm.

[0038] The surface roughness Sa of the diamond particles is 20–90 nm.

[0039] The BET specific surface area of ​​the diamond particles after etching is not less than 0.014 m². 2 ·g -1 Furthermore, its BET specific surface area is more than 50 times that of unetched diamond particles of the same size.

[0040] Preferably, the diamond volume fraction is 50 vol%, and the thermal conductivity of the composite material is ≥ 700 W·m. -1 ·K -1The thermal conductivity of the composite material can be determined by laser scintillation to measure thermal diffusivity, and calculated in conjunction with sample density and specific heat capacity; the preferred test temperature is room temperature (25°C ± 2°C). The aforementioned etched diamond-copper composite material containing a Mo2C transition layer is prepared by etching diamond, then using the etched diamond and copper powder as raw materials, depositing a carbide layer on the diamond surface using a molten salt method, and finally bonding it with copper powder using a vacuum hot pressing method.

[0041] Specifically, the present invention provides a method for preparing an etched diamond-copper composite material containing a Mo2C transition layer, comprising the following steps: Step 1: Take diamond particles with an average particle size of about 50-200 μm and place them in an H2SO4 solution with a concentration of 0.2-1.0 mol / L (preferably 0.5 mol / L) for ultrasonic cleaning for 20-60 min; after removing them, transfer them to a NaOH solution with a concentration of 0.2-1.0 mol / L (preferably 0.5 mol / L) for ultrasonic cleaning for 20-60 min to neutralize the acid residue; then ultrasonically clean them 2-5 times with deionized water, 20-60 min each time, filter and collect for later use.

[0042] Step 2: Place the cleaned diamond from Step 1 in a drying oven at 50-80℃ for 2-3 hours to remove residual moisture.

[0043] Step 3: Place the dried diamond from Step 2 into a muffle furnace and heat it to 600–800℃ in an air atmosphere, holding it at this temperature for 20–60 minutes to form a crystal orientation-selective micropit structure on the diamond surface. After holding, allow it to cool naturally to room temperature with the furnace, obtaining the etched diamond. The oxygen sintered in the muffle furnace can oxidize the C (sp³) on the diamond surface step by step into CO / CO2 and remove atoms. Different crystal faces have different reaction rates, thus growing regular triangular or rectangular etching pits, thereby increasing the surface roughness and specific surface area of ​​the diamond particles. Furthermore, according to… Figure 5 The Raman diagram shows that etching does not change the structure of diamond.

[0044] Step 4: Weigh the diamond and molybdenum powder at a mass ratio of 1:0.65 and mix them thoroughly. Separately, mix NaCl and KCl at a mass ratio of 1:1 and grind them into a mixed salt. Cover the surface of the mixed powder with the mixed salt to form a molten salt reaction system.

[0045] Step 5: Place the charge obtained in Step 4 into a vacuum tube furnace and evacuate to 1×10⁻⁶. -3Pa, heating to 1100℃ at 3-5℃ / min and holding for 30 min, allows the molybdenum source to react with carbon on the diamond surface in situ in a molten salt environment to generate a Mo2C transition layer; after natural cooling to room temperature, the powder is removed, repeatedly washed with deionized water until the salt is completely removed, and then dried to obtain diamond particles with a Mo2C transition layer on the surface.

[0046] Step 6: Place copper powder in a tube furnace and introduce H2 atmosphere. Anneal and reduce at 400-600℃ for 20-60 minutes to remove surface oxides. After cooling, remove and set aside for later use.

[0047] Step 7: Weigh the Mo2C-coated diamond from Step 5 and the reduced copper powder from Step 6 according to the designed diamond volume fraction (preferably 30-60 vol%), and mix them in a mixer for 0.5-2 hours to make them uniform; then load the mixed powder into a pre-prepared mold.

[0048] Step 8: Place the powdered graphite mold in a vacuum hot pressing sintering furnace, heat it to 850°C under vacuum conditions, apply a vertical pressure of 40 MPa and hold it at that temperature for 60 min to densify the composite material; then let it cool naturally to room temperature in the furnace and demold to obtain the diamond copper composite material.

[0049] Implementation Case 1 Take 60g of diamond powder with a particle size of about 200μm and place it in 300ml of 0.5mol / L H2SO4 solution for ultrasonic cleaning for 30min. Then place the cleaned diamond powder in 300ml of 0.5mol / L NaOH solution for ultrasonic cleaning for 30min. Finally, rinse twice with deionized purified water for 30min each time and dry in an oven for 3h.

[0050] The dried diamonds were divided into three groups and placed in muffle furnaces for oxidation etching in air atmosphere. The holding time for each group was 30 minutes, and the etching temperatures were 500°C, 700°C, and 900°C, respectively. After natural cooling, analysis revealed the following: (1) 500°C treatment group (see Figure 2 ): Only a few shallow corrosion spots appeared on the diamond surface, indicating insufficient etching.

[0051] (2) 700°C treatment group (see) Figure 3 ): Dense, uniform, and appropriately deep regular micro-pits are formed on the diamond surface. The (111) face is an inverted triangular pit and the (100) face is a rectangular pit. The diamond crystal structure remains intact, which is the optimal etching morphology.

[0052] (3) 900°C treatment group (see) Figure 4The diamond particles were severely over-oxidized, resulting in blunted edges and powdering and peeling, which damaged the diamond crystal phase.

[0053] Based on the above results, 600-800°C, preferably 700°C, was selected as the optimal etching temperature for subsequent preparation.

[0054] Take the diamond etched at 700°C and mix them evenly at a ratio of Dia / Mo = 1 / 0.65 (g). Then, take 1.25g each of NaCl and KCl, mix and grind them together, and place the mixed salt powder on top. Place the quartz crucible containing the mixed powder in a vacuum tube furnace and heat it at a rate of 4°C / min with a vacuum degree of 1×10⁻⁶. -3 The temperature was raised to 1100°C and held for 30 minutes, then allowed to cool naturally to room temperature. The sintered powder was repeatedly washed in deionized water until all salts were removed (the water was clear and free of turbidity), and dried to obtain surface-metallized diamond. 15g of copper powder was reduced in a tube furnace at 500°C under H2 atmosphere for 30 minutes. 0.334g of surface-metallized diamond and 1.985g of reduced copper powder were weighed and mixed in a mixer for 1 hour until homogeneous. A cylindrical sample with a diameter of 12.7mm and a height of 2.5mm was prepared. The mold was then held at 850°C for 60 minutes in a vacuum hot-pressing sintering furnace and allowed to cool naturally to room temperature. The sintered sample was designated N1.

[0055] Comparison Case 1 The diamond was prepared according to the method described in Example 1, the only difference being that the diamond was not subjected to muffle furnace oxidation etching. The cleaned and dried raw diamond was directly mixed uniformly at a ratio of Dia / Mo = 1 / 0.65 (g) and coated with a mixed salt for molten salt plating. 0.334g of the surface-metallized diamond and 1.985g of reduced copper powder were weighed and mixed in a mixer for 1 hour until uniformly mixed. All other parameters for molten salt plating, copper powder reduction, and vacuum hot pressing sintering were completely consistent with Example 1. The sintered sample was designated M1.

[0056] Implementation Case 2 The sample was prepared according to the method described in Example 1, with the only difference being the adjustment of the feed mass of diamond and copper powder to change the volume fraction. 0.446 g of surface-metallized diamond (etched at the preferred 700°C temperature in Example 1) and 1.702 g of reduced copper powder were weighed on a balance and mixed in a mixer for 1 hour until homogeneous. All other raw material pretreatment, molten salt plating, and vacuum hot pressing sintering parameters were completely consistent with those in Example 1. The sintered sample was designated N2.

[0057] Comparison Case 2 The sample was prepared according to the method described in Comparative Case 1, with the only difference being the mass of diamond and copper powder used. 0.446g of surface-metallized diamond (unetched) and 1.702g of reduced copper powder were weighed and mixed in a mixer for 1 hour until homogeneous. All other process parameters were identical to those in Comparative Case 1. The fired sample was designated M2.

[0058] Implementation Case 3 The sample was prepared according to the method described in Example 1, with the only difference being the adjustment of the feed mass of diamond and copper powder to change the volume fraction. 0.557 g of surface-metallized diamond (using the preferred 700°C etching conditions in Example 1) and 1.418 g of reduced copper powder were weighed on a balance and mixed in a mixer for 1 hour until homogeneous. All other raw material pretreatment, molten salt plating, and vacuum hot pressing sintering parameters were completely consistent with Example 1. The sintered sample was designated N3.

[0059] Comparison Case 3 The sample was prepared according to the method described in Comparative Case 1, with the only difference being the mass of diamond and copper powder used. 0.557g of surface-metallized diamond (unetched) and 1.418g of reduced copper powder were weighed and mixed in a mixer for 1 hour until homogeneous. All other process parameters were identical to those in Comparative Case 1. The fired sample was designated M3.

[0060] Implementation Case 4 The sample was prepared according to the method described in Example 1, with the only difference being the adjustment of the feed mass of diamond and copper powder to change the volume fraction. 0.669 g of surface-metallized diamond (etched at the preferred 700°C temperature in Example 1) and 1.134 g of reduced copper powder were weighed on a balance and mixed in a mixer for 1 hour until homogeneous. All other raw material pretreatment, molten salt plating, and vacuum hot pressing sintering parameters were completely consistent with Example 1. The sintered sample was designated N4.

[0061] Comparison Case 4 The preparation method was the same as in Comparative Case 1, with the only difference being the mass of diamond and copper powder used. 0.669g of surface-metallized diamond (unetched) and 1.134g of reduced copper powder were weighed and mixed in a mixer for 1 hour until homogeneous. All other process parameters were identical to those in Comparative Case 1. The fired sample was designated M4. Experimental Results Analysis To verify the performance advantages of the diamond-copper composite material synergistically constructed by etching and a Mo2C transition layer as described in this invention, the microstructure and thermophysical properties of samples prepared in the above-mentioned implementation examples (N series) and comparative examples (M series) were characterized, and the effects under different process parameters were compared and analyzed. Figure 6As shown in the figure, (a) and (b) are two-dimensional planar morphology diagrams of different crystal planes of diamond particles after etching; (c) is a two-dimensional planar morphology diagram of unetched diamond particles; (d) and (e) are three-dimensional planar morphology diagrams of diamond particles with different crystal planes after etching; (f) is a three-dimensional planar morphology diagram of unetched diamond particles. It can be seen that the roughness of diamond particles after etching is significantly increased. Figure 7 The figures show the nitrogen adsorption isotherms and BET specific surface area analysis results of diamond particles before and after etching in this invention. Figure (a) shows that the specific surface area of ​​the unetched diamond is 0.0002 m². 2 ·g -1 Figure (b) shows a depth of 0.0148 μm after etching. 2 ·g -1 This indicates that the etching process significantly increased the specific surface area of ​​the diamond particles (approximately 74 times). Figure 8 As shown, the microstructure of the unetched M3 sample in Comparative Case 3 after molten salt treatment is illustrated; (a) is a SEM image of the diamond particle surface, showing the coating coverage; (b) is an observation image of the carbide layer thickness. Figure 9 As shown, the microstructure of the N3 sample etched in Example 3 after molten salt treatment is shown; (a) is a SEM image of the diamond particle surface, showing the coating coverage; (b) is an observation image of the carbide layer thickness.

[0062] First, regarding the impact of the core etching process of this invention on material properties, a comparison is made between Example 1 (30 vol% etched sample N1) prepared using the process of this invention and Comparative Example 1 (30 vol% unetched sample M1). Combined with... Figure 12 The thermal conductivity test results show that, under the same diamond volume fraction, the thermal conductivity of the sample in Comparative Case 1 is 519 W·m. -1 ·K -1 The sample in Implementation Case 1 benefited from the mechanical interlocking effect formed by the micro-pits etched on the diamond surface, which effectively reduced the interfacial thermal resistance, increasing its thermal conductivity to 546 W·m. -1 ·K -1 The improvement was approximately 5.2%. This indicates that the physical anchor points constructed by oxidation etching in this invention can significantly enhance the interface heat transfer efficiency, proving the necessity and effectiveness of the etching process.

[0063] Secondly, regarding the selection of temperature parameters in the etching process, based on the diamond surface morphology after different temperature treatments in Implementation Case 1 (see... Figures 2 to 4It can be seen that at 500°C, the oxidation rate of the diamond surface is slow, resulting in only shallow spots, and the etching depth is insufficient to form an effective mechanical interlocking structure. However, at 900°C, the diamond particles undergo excessive oxidation, leading to blunting of the edges and granulation and spalling of the crystals, severely damaging the intrinsic structure of the reinforcement. In contrast, the diamond surface treated at 700°C forms uniformly distributed, appropriately deep, and regular geometric micropits ((111) facets are triangular, and (100) facets are rectangular), and the crystal structure remains intact. Therefore, this invention preferably uses 600-800°C as the optimal etching temperature and 700°C as the best etching temperature. These process parameters maximize the specific surface area and bonding force while ensuring the strength of the diamond skeleton.

[0064] Compared to the expensive processes such as "hydrogen plasma etching" or "vacuum sputtering" used in existing technologies, this invention demonstrates extremely high industrial application value. While existing technologies can also improve interfaces, they rely on high-vacuum equipment, high-purity gas sources, and prolonged plasma bombardment, resulting in high equipment costs and difficulty in large-scale continuous powder processing. In contrast, this invention employs "muffle furnace air oxidation etching," using air as the reaction source, enabling batch processing in conventional heating equipment, making the process extremely simple. More importantly, performance tests show that, as Figure 12 As shown, the sample (50 vol%) of Example 3 prepared using the low-cost process of this invention has a thermal conductivity as high as 706 W·m. -1 ·K -1 This value is comparable to or even surpasses that of similar materials prepared using complex vacuum processes. This demonstrates that the present invention has successfully developed a "low-cost, high-performance" alternative, overcoming the shortcomings of existing high-end heat dissipation materials, such as high production barriers and difficulty in mass production.

[0065] Finally, regarding the effect of the ratio (volume fraction) of diamond to reduced copper powder on the properties of the composite material, a series of samples from Example 1 to Example 4 (corresponding to volume fractions of 30 vol% to 60 vol%) were compared. Figure 10 As shown, the cross-sectional SEM microstructure and partial magnification images of the diamond-copper composite materials prepared from the M3 sample (unetched) and N3 sample (etched) with a volume fraction of 50 vol% in Case 3 are presented. Figure 11 The image shows a comparison of the SEM morphology of the composite material cross-sections of embodiments 1, 2, and 4 of this invention with comparative embodiments 1, 2, and 4, at different diamond volume fractions (30 vol%, 40 vol%, 60 vol%). Experimental data (see [link to relevant documentation]). Figure 12(Figure (a) shows the thermal conductivity comparison, and (b) shows the density performance comparison). With increasing diamond volume fraction, the thermal conductivity of the composite material first increases and then decreases. In the range of 30 vol% to 50 vol%, the introduction of a high thermal conductivity reinforcing phase increases the heat flow channels, significantly improving thermal conductivity; in Example 3 (50 vol%), the material's thermal conductivity reaches a peak of 706 W·m. -1 ·K -1 And the density remained at 6.13 g / cm³. 3 The density was at a high level. However, when the volume fraction was further increased to 60 vol% (Example 4), despite the use of etching processes to improve wettability, the agglomeration effect between particles still caused the density to decrease to 5.44 g / cm³. 3 Increased interface defects lead to a decrease in thermal conductivity. The thermal conductivity of composite materials can be determined by measuring thermal diffusivity using laser scintillation and calculated in conjunction with sample density and specific heat capacity, such as... Figure 13 As shown, at room temperature (25°C ± 2°C), the thermal conductivity of the etched sample with a diamond volume fraction of 50 vol% tends to be high. In summary, this invention selects Example 3 (diamond volume fraction of 50 vol%) as the optimal ratio of diamond to copper powder, at which point the material achieves optimal thermal conductivity while maintaining high density.

[0066] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. An etched diamond-copper composite material containing a Mo2C transition layer, characterized in that: The composite material includes a copper matrix and diamond particles dispersed in the copper matrix; the diamond particles are etched to form a micropit structure on the surface of the copper matrix; the surface of the diamond particles is coated with a nanoscale Mo2C transition layer generated in situ by molten salt reaction, and a Cu / Mo2C / diamond three-layer interface structure is formed between the diamond particles and the copper matrix; wherein the copper matrix at least partially fills the micropit structure to form mechanical intercalation and reduce interface defects.

2. The composite material according to claim 1, characterized in that, The crystal facets of the diamond particles include a (100) facet and a (111) facet, wherein the (100) facet forms a rectangular etching pit and the (111) facet forms a triangular etching pit. The depth of the micro-pit is 0.2–1.4 μm.

3. The composite material according to claim 1, characterized in that: The surface roughness Sa of the diamond particles is 20–90 nm; the BET specific surface area of ​​the etched diamond particles is not less than 0.014 m²·g. -1 .

4. The composite material according to claim 1, characterized in that: The diamond volume fraction is 30–60 vol%, and the thermal conductivity of the composite material is ≥ 700 W·m. -1 ·K -1 .

5. A method for preparing the composite material according to any one of claims 1 to 4, characterized in that, The process includes the following steps: Step 1: Cleaning and drying diamond particles; Step 2: Oxidizing and etching diamond particles in an oxygen-containing atmosphere using a muffle furnace to form a micro-pit structure on their surface; Step 3: Vacuum reaction of the etched diamond particles with a molybdenum source in a NaCl and KCl molten salt environment to generate a Mo2C transition layer in situ on the diamond surface, followed by cleaning, desalting, and drying; Step 4: Annealing and reducing copper powder in a hydrogen atmosphere; Step 5: Mixing copper powder with Mo2C-coated diamond particles and then vacuum hot-pressing and sintering to form the final shape.

6. The method according to claim 5, characterized in that: In step two, the temperature of the muffle furnace is 600–800℃, and the holding time is 20–60 min.

7. The method according to claim 5, characterized in that: In step three, the mass ratio of NaCl to KCl is 1:1, and the vacuum degree is 1×10⁻⁶. -3 Pa, heating rate 3-5℃ / min, heat to 1100℃ and hold for 30 min.

8. The method according to claim 5, characterized in that: In step four, the copper powder is annealed and reduced at 500°C under an H2 atmosphere.

9. The method according to claim 5, characterized in that: In step five, the volume fraction of diamond is 30–60 vol%.

10. The composite material according to any one of claims 1 to 4, characterized in that, The composite material is used in electronic packaging heat dissipation substrates, power device heat dissipation base plates, or high heat flux density heat dissipation components.

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