Diamond-copper composite material additive manufacturing method

Abstract

The invention discloses a diamond-copper composite material additive manufacturing method. The method comprises the steps that a composite material forming a weakening interface is prepared; under inert atmosphere protection, selective laser melting printing is conducted on the basis of the composite material forming the weakening interface, and a three-dimensional entity of the to-be-machined part with a machinable transient region is obtained; the three-dimensional entity of the to-be-machined part with the machinable transient region is machined, and the diamond-copper composite material part with the precision machining characteristic is obtained; performing low-temperature heat treatment on the diamond-copper composite material part with the precision machining characteristic to obtain a diamond-copper composite material final part capable of being precisely machined; and the diamond-copper composite material final part capable of being precisely machined is subjected to infiltration treatment, and the diamond-copper composite material part with the interface reconstructed is obtained.

Description

Technical Field

[0001] This application belongs to the field of materials preparation and additive manufacturing technology, specifically relating to an additive manufacturing method for diamond-copper composite materials. Background Technology

[0002] With the development of 5G communication, high-performance computing, and power electronic devices, the heat flux density of heat dissipation components has increased dramatically, placing higher demands on heat dissipation materials. Diamond-copper composites, due to their combination of diamond's ultra-high thermal conductivity and copper's good ductility, are considered ideal thermal management materials. However, their industrial applications face severe processing challenges: existing additive manufacturing combined with melt infiltration or powder metallurgy pressureless sintering methods can achieve complex forming or densification, but either it is difficult to perform precision machining on ultra-hard materials after densification, or the introduction of alloying elements affects the thermal and electrical conductivity of the material. Neither method can achieve efficient and precise machining of complex structures while obtaining high-performance materials. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the purpose of this application is to provide an additive manufacturing method for diamond-copper composite materials. This application aims to solve the manufacturing problem of diamond-copper composite materials that are difficult to achieve precision machining while ensuring high thermal conductivity by using a removable weakened interface design and a staged post-processing process.

[0004] To achieve the above objectives, this application provides the following technical solution: A method for additive manufacturing of diamond-copper composite materials, the method comprising: preparing a composite material forming a weakened interface; performing selective laser melting printing on the composite material forming the weakened interface under an inert atmosphere to obtain a three-dimensional solid of a part to be processed having a machinable transient region; machining the three-dimensional solid of the part to be processed having a machinable transient region to obtain a diamond-copper composite material part with precision machining characteristics; subjecting the diamond-copper composite material part with precision machining characteristics to low-temperature heat treatment to obtain a precision-machinable diamond-copper composite material final part; and subjecting the precision-machinable diamond-copper composite material final part to melt infiltration treatment to obtain a diamond-copper composite material part with interface reconstruction.

[0005] Optionally, the preparation of the composite material forming the weakened interface includes: pretreating the diamond particles; coating the surface of the pretreated diamond particles with a tungsten carbide layer to obtain a matrix interface layer; depositing a dense copper layer on the matrix interface layer; and wrapping the surface of the copper-plated diamond particles with a low-melting-point isolation layer to obtain a composite material containing a removable weakened interface.

[0006] Optionally, the pretreatment of the diamond particles includes: cleaning the diamond particles; etching the surface of the cleaned diamond particles; activating the etched diamond particles; and depositing a titanium or chromium metal layer on the surface of the activated diamond particles.

[0007] Optionally, the step of coating the surface of the pretreated diamond particles with a tungsten carbide layer to obtain a matrix interface layer includes: depositing an amorphous carbon-tungsten transition layer on the surface of the pretreated diamond particles in a mixed atmosphere of a tungsten-containing organic precursor and methane; and epitaxially growing a tungsten carbide layer on the surface of the amorphous carbon-tungsten transition layer in a mixed atmosphere of tungsten halides and hydrocarbons.

[0008] Optionally, the step of selective laser melting printing based on the composite material forming the weakened interface under an inert atmosphere to obtain a three-dimensional solid of the part to be processed with a processable transient region includes: spreading the composite material forming the weakened interface on a preheated powder-coated substrate in a selective laser melting device; printing the spread composite material forming the weakened interface separately; repeating the above steps until the three-dimensional structure of the part is printed, obtaining a three-dimensional solid of the part to be processed with overall density and local weakened interfaces.

[0009] Optionally, the step of differentially printing the laid composite material forming the weakened interface includes: printing the main part area of ​​the composite material using high energy density parameters; and printing the processable transient area of ​​the composite material using low energy density parameters.

[0010] Optionally, the step of machining the three-dimensional solid of the part to be machined with a machinable transient region to obtain a diamond-copper composite material part with precision machining characteristics includes: clamping and positioning the three-dimensional solid of the part to be machined with a machinable transient region; setting machining parameters; performing step-by-step machining operations on the clamped three-dimensional solid according to the set machining parameters; and performing transient protection and transfer of the machined three-dimensional solid.

[0011] Optionally, the step of performing low-temperature heat treatment on diamond-copper composite parts with precision machining characteristics to obtain precision-machinable diamond-copper composite final parts includes: heating the diamond-copper composite parts; performing pulsed negative pressure extraction and surface adsorption on the heated diamond-copper composite parts; performing interface purification on the diamond-copper composite parts after pulsed negative pressure extraction and surface adsorption; and cooling the diamond-copper composite parts after interface purification.

[0012] Optionally, the heating treatment of the diamond-copper composite material parts includes: heating the diamond-copper composite material parts through multi-stage gradient heating.

[0013] Optionally, the process of performing melt infiltration treatment on the precision-machinable diamond-copper composite final part to obtain a diamond-copper composite part with reconstructed interface includes: performing melt infiltration on the precision-machinable diamond-copper composite final part using dual-temperature synergistic heating; assisting infiltration of copper liquid in the initial stage of melt infiltration; introducing a trace amount of Ti / Cr precursor vapor to undergo an in-situ reaction at the tungsten carbide-copper liquid interface during the melt infiltration and heat preservation stage; and performing cooling and stress relief treatment on the precision-machinable diamond-copper composite final part after the in-situ reaction to obtain a diamond-copper composite part with reconstructed interface.

[0014] Compared with the prior art, the beneficial effects of this application are as follows: This application constructs a composite material containing a "removable weakened interface" and selectively laser-melts the printing process to form a temporary weak bonding state in a pre-defined processing area, enabling efficient and precise machining. Subsequently, the weakened interface is selectively removed through low-temperature heat treatment and copper melt is infiltrated a second time, restoring the diamond-copper strong interface bonding in the processing area to be consistent with the original material. This ensures that the high thermal conductivity and high electrical conductivity of the composite material are not compromised while fully preserving the complex geometric features. Attached Figure Description

[0015] Figure 1 This is a schematic flowchart of an additive manufacturing method for diamond-copper composite materials according to an embodiment of this application; Figure 2 The image shows a metallographic image of a diamond-copper composite material prepared using traditional methods. Figure 3 This is a metallographic image of the diamond-copper composite material prepared based on this application. Detailed Implementation

[0016] Specific embodiments of this application will now be described in detail with reference to the accompanying drawings. While specific embodiments of this application are shown in the drawings, it should be understood that this application can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this application and to fully convey the scope of this application to those skilled in the art.

[0017] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions in the specification are preferred embodiments for carrying out this application; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of this application. The scope of protection of this application shall be determined by the appended claims.

[0018] To facilitate understanding of the embodiments of this application, the following will provide further explanation and description with reference to the accompanying drawings and specific embodiments, and the accompanying drawings do not constitute a limitation on the embodiments of this application.

[0019] Figure 1 This is a schematic flowchart of an additive manufacturing method for high thermal conductivity diamond-copper composite materials provided in an exemplary embodiment of this application. The method includes the following steps: S100: Prepare a composite material that forms a weakened interface; S200: Under the protection of an inert atmosphere, selective laser melting printing is performed on the composite material that forms the weakened interface to obtain a three-dimensional solid of the part to be processed with a processable transient region. S300: Machining a three-dimensional solid of a workpiece with a machinable transient region to obtain a diamond-copper composite material part with precision machining characteristics; S400: Low-temperature heat treatment is performed on diamond-copper composite parts with precision machining characteristics to obtain precision-machinable diamond-copper composite final parts. S500: Performs melt infiltration treatment on precision-machinable diamond-copper composite final parts to obtain diamond-copper composite parts with reconstructed interfaces.

[0020] In another exemplary embodiment, step S100, the preparation of the composite material forming the weakened interface, includes the following steps: S101: Pretreatment of diamond particles, specifically including: First, place the diamond particles in a mixture of acetone and ethanol and ultrasonically clean them for 15 to 30 minutes. Then rinse them with deionized water until neutral and dry them for later use. Next, the cleaned diamond particles are immersed in a hydrofluoric acid-nitric acid mixed solution (volume ratio 1:3) and etched at 60°C to 80°C for 30 to 60 minutes to form a uniform micron / submicron-scale pit structure on the surface of the diamond particles. This pit structure increases the effective contact area and roughness of the diamond particle surface, providing more physical anchoring points for subsequent coatings, thereby enhancing the mechanical interlocking effect. At the same time, the curvature effect of the pit edges can promote the effective filling and encapsulation of subsequent coating materials during the deposition process, improve interfacial wettability and bonding continuity, and alleviate interfacial stress concentration caused by the mismatch of thermal expansion coefficients, ultimately synergistically improving the adhesion and bonding stability between the coating and the diamond substrate.

[0021] Next, the etched diamond particles are placed in a tube furnace for oxidation activation treatment. The temperature is increased to 500°C to 600°C at a rate of 5°C / min to 10°C / min in an air atmosphere and held for 1 to 2 hours. This generates active groups such as -OH and -COOH on the surface of the diamond particles, thereby improving the surface energy and wettability of the diamond particles.

[0022] Finally, a titanium or chromium metal layer with a thickness of approximately 2 nm to 5 nm is deposited on the oxidized and activated diamond surface using magnetron sputtering or electron beam evaporation. This metal layer can act as a highly efficient catalyst in the subsequent chemical vapor deposition process, promoting the decomposition of the carbon source at a lower temperature and providing a bridge for carbon atom migration, thereby driving the uniform and dense low-temperature epitaxial growth of the tungsten carbide layer on the diamond surface. At the same time, this metal layer can preferentially react with carbon to generate transition carbides (such as TiC and Cr3C2) with high phonon conductivity, forming a gradient interface structure with diamond and tungsten carbide. This not only significantly enhances the interfacial bonding strength through chemical bonding and lattice matching, but also effectively reduces phonon scattering and alleviates thermal mismatch stress, thereby helping to synergistically improve the thermal conductivity of the interface between diamond particles and the copper substrate, and enhance the bonding stability of the interface between the carbide transition layer on the diamond particle surface and the copper substrate.

[0023] S102: A tungsten carbide layer is coated on the surface of the pretreated diamond particles to obtain a matrix interface layer; In this step, this embodiment employs a multi-mode gradient chemical vapor deposition method to achieve tungsten carbide coating. Specifically, it includes: First, introducing a mixed atmosphere of tungsten-containing organic precursors (such as tungsten hexacarbonyl) and methane at a relatively low temperature (e.g., 500°C to 650°C), and forming an amorphous carbon-tungsten transition layer on the pretreated diamond surface through plasma-enhanced chemical vapor deposition. The amorphous structure in this transition layer has isotropic and adjustable atomic packing density and bonding state, allowing its thermal expansion coefficient to achieve a continuous gradient transition between the diamond particles and the subsequently deposited crystalline tungsten carbide or metal layer. At the same time, the carbon-tungsten mixed bonding can form a strong bond with the carbon atoms on the diamond surface, and can also absorb and disperse the interfacial shear stress caused by thermal cycling through its disordered structure, thereby suppressing interfacial delamination or crack initiation caused by abrupt changes in thermal expansion coefficient, and improving the structural stability of the composite material under thermal shock. Subsequently, the temperature is gradually increased in a hydrogen atmosphere (from 5°C / min to 10°C / min, gradually increasing to the medium-high temperature deposition window (e.g., 750°C to 950°C)), and the precursor is switched to a mixture of tungsten halides (e.g., tungsten hexafluoride) and hydrocarbons (e.g., methane, propane, or ethylene). Through pulsed gas inlet and periodic pressure control, the locally short-range ordered tungsten-carbon clusters in the amorphous carbon-tungsten layer are used as epitaxial nucleation sites. Under plasma enhancement or thermal activation, the tungsten and carbon sources decompose and epitaxially grow on the transition layer surface, forming a dense tungsten carbide layer with a columnar nanocrystalline structure. It should be noted that this dense tungsten carbide layer with columnar nanocrystalline structure not only provides excellent interfacial bonding strength and thermal conductivity transfer path, but its grain boundary interstices can also serve as capillary channels during subsequent copper infiltration, enhancing the wetting and coating integrity of diamond particles by molten copper, ultimately forming a continuous, uniform, and thermodynamically stable matrix interface layer.

[0024] S103: Deposit a dense copper layer on the substrate interface layer; In this step, diamond particles with a substrate interface layer are first immersed in an acidic plating bath containing copper ions. Without an applied current, a spontaneous displacement reaction occurs due to the electrochemical potential difference between tungsten carbide and copper, forming an extremely thin but highly continuous nano-copper seed layer on the surface of the substrate interface layer. Subsequently, the process switches to pulsed current electroplating mode. By precisely controlling the pulse frequency, duty cycle, and reverse current amplitude, a dense copper layer without pores and with low internal stress is epitaxially grown layer by layer on the seed layer. At this point, a semi-coherent crystalline match can be formed between the copper layer and the tungsten carbide interface, which helps to improve the interfacial bonding strength and thermal conductivity, providing a highly active metal substrate for the uniform adhesion of the subsequent low-melting-point isolation layer.

[0025] S104: A low-melting-point insulating layer is coated on the surface of copper-plated diamond particles to obtain a composite material containing a removable weakened interface.

[0026] In this step, this embodiment achieves uniform encapsulation of a low-melting-point isolation layer through low-temperature chemical vapor deposition and sol-gel composite technology. Specifically, it includes: first, placing copper-plated diamond particles in a reaction chamber filled with bismuth or bismuth-tin organic precursor vapor, and depositing an amorphous metal-carbon composite transition film on the outside of a dense copper layer under mild conditions of 150°C to 200°C using surface catalytic pyrolysis reaction to enhance interfacial bonding; then immersing the particles in an organic sol containing nano-bismuth particles, and uniformly adhering the sol through ultrasonic assistance and centrifugal spin coating, followed by short-term heat treatment under an inert atmosphere at a recrystallization temperature lower than that of copper, causing the sol to transform into a continuous, dense, and controllable-thickness low-melting-point metal isolation layer. This isolation layer exhibits a layered structure with nanopores at the microscopic level, which can form a separable weak interface through local melting during SLM printing, and can also be completely removed through capillary exudation and volatilization during subsequent heat treatment, thereby achieving a reversible "processing-recovery" function and endowing the composite material with unique transient processability.

[0027] In another exemplary embodiment, step S200, which involves selective laser melting printing based on the composite material forming the weakened interface under an inert atmosphere to obtain a three-dimensional solid of the part to be processed with a machinable transient region, includes the following steps: S201: In a selective laser melting device, a composite material that forms a weakened interface is spread on a preheated powder-coated substrate; In this step, the powder-coated substrate is preheated to 80°C to 120°C in a selective laser melting device under an inert atmosphere (such as high-purity argon with an oxygen content of <100 ppm) to reduce thermal stress. Subsequently, the composite material forming the weakened interface is uniformly spread on the substrate, with a single layer thickness set, for example, to 30 μm to 50 μm, and the smoothness of the powder coating is ensured by using a scraper or roller.

[0028] S202: Differentiate printing on the laid composite material that forms a weakened interface; In this step, during the selected area laser melting printing process, conventional high energy density parameters are used for printing the main body area of ​​the part (non-machinable transient area) to ensure complete overall densification. Specific parameters include: laser power set to 250W to 350W, scanning speed set to 800mm / s to 1200mm / s, scanning spacing set to 0.08mm to 0.12mm, and layer thickness set to 30μm. A checkerboard or stripe rotation scanning strategy is used to optimize heat distribution and forming strength. When printing to the preset machinable transient area (such as the layer containing the mounting surface or holes), the parameters are switched to low energy density, such as: laser power adjusted to 150W to 220W, scanning speed adjusted to 1200mm / s to 1800mm / s, scanning spacing adjusted to 0.10mm to 0.15mm, and energy density controlled at approximately 40J / mm². 3 Up to 70J / mm 3 The melting point is only 50% to 70% of the non-transient region, which allows the low-melting-point isolation layer in the composite material to completely melt and wet the copper layer. At the same time, it avoids the full alloying of copper and tungsten carbide layers or diamond graphitization. After the molten pool solidifies rapidly, the low-melting-point metal can be solidified in the form of a continuous or semi-continuous film between the diamond-copper interface, forming a temporary weak bonding region with a macroscopic hardness reduced to HV 150 to 250. This allows the part to have a locally machinable transient weak interface characteristic while being formed into a dense overall shape.

[0029] In summary, the core purpose of differentiated printing of composite materials is to achieve localized and controllable differentiation of material properties within a single manufacturing process. Specifically, by employing a specific low-energy scanning strategy for areas requiring subsequent precision machining (i.e., the "machinable transient zone"), it is possible to ensure that the low-melting-point insulating layer in this area melts but does not fully alloy with the matrix, thus preserving its weak bonding characteristics. For high-performance areas that do not require machining, standard high-energy parameters are used to achieve a strong metallurgical bond between diamond and the copper matrix. This differentiated energy input strategy ensures that after the part is integrally formed, it not only guarantees the high thermal conductivity and high strength of the main structure but also creates a reversible "machining window" in a predetermined area. This creates the necessary conditions for subsequent efficient and low-loss precision machining, ultimately achieving a balance between structural complexity and functional integrity during the manufacturing process.

[0030] S203: Repeat the above steps until the three-dimensional structure of the part is printed, and obtain a three-dimensional solid of the part to be processed that is dense overall but has a weakened interface in some local (machinable transient areas).

[0031] In another exemplary embodiment, step S300, which involves machining the three-dimensional solid of the part to be machined, which has a machinable transient region, to obtain a diamond-copper composite material part with precision machining features, includes the following steps: S301: Clamping and positioning of a three-dimensional solid part with a machinable transient region; In this step, the present application uses a customized fixture, which is fixed to the rigid surface of the non-transient area of ​​the part by three-point positioning or contour support. At the same time, optical scanning or contact probe is used to help identify the precise position of the transient area in the machine tool coordinate system, so as to achieve full-domain rigid constraint of the part and precise alignment of the transient area during the machining process, providing a stable and reliable process foundation for subsequent precision milling or drilling.

[0032] S302: Set machining parameters; In this step, considering the characteristics of the "machinable transient zone"—low hardness (HV150 to 250) but easy interface peeling—fine-grained carbide multi-flute end mills and diamond-coated drills are selected, with a cutting edge rake angle ≥10° to ensure sharpness. The cutting parameters are optimized as follows: milling speed 4000 rpm to 6000 rpm, feed rate 300 mm / min to 600 mm / min, depth of cut ≤0.2 mm; drilling speed 2000 rpm to 4000 rpm with a stepped feed strategy. Simultaneously, micro-lubrication and low-temperature mist cooling are employed to strictly control the temperature rise in the cutting zone below 100°C, preventing premature softening of the low-melting-point isolation layer or interface healing, ensuring a stable and efficient machining process.

[0033] S303: Perform step-by-step machining operations on the clamped three-dimensional solid according to the set machining parameters; In this step, this embodiment follows the principle of "surface first, then hole; roughing first, then finishing" to process the three-dimensional solid in stages. Specifically, it includes: First, the mounting surface is precision milled using a spiral infeed to ensure flatness ≤ 0.02 mm and roughness Ra ≤ 1.0 μm; then, H7 grade precision holes are drilled and 6H grade threads are tapped, with periodic chip removal to avoid chip accumulation; second, the irregular contour is finished after leaving a 0.05 mm to 0.10 mm allowance.

[0034] The above processing is monitored in real time by acoustic emission sensors. If an abnormal increase is detected (indicating a risk of interface peeling), the process is immediately paused and the parameters are adjusted to achieve controllability and adaptability of the processing.

[0035] It should be noted that the purpose of adopting the above-mentioned step-by-step machining strategy is to ensure the geometric accuracy and surface quality of the machinable transient zone by controlling the accumulation of machining stress and heat in stages. Specifically, the spiral entry milling first establishes a high-precision mounting reference plane, providing a reliable positioning reference for subsequent hole machining; then, high-precision holes are drilled and tapped, and periodic chip removal effectively avoids chip entanglement and heat concentration, ensuring the quality of the hole wall and the integrity of the thread; finally, a small amount of material is used for fine finishing of the irregular contour, which releases the residual stress that may have been introduced by the previous machining while avoiding overcutting. Ultimately, the part can efficiently and stably achieve the precision dimensional requirements and excellent surface integrity in a weakened state, and lay a reliable geometric foundation for subsequent heat treatment and performance recovery processes.

[0036] S304: Perform transient protection and sequence transfer on the completed 3D solid.

[0037] In this step, the processed parts are placed in a 100°C vacuum drying oven to remove adsorbed moisture and prevent moisture-induced oxidation during subsequent heat treatment. They are then packaged in argon-filled sealed bags containing an oxygen indicator and labeled "Processed - Pending Post-Processing". The transfer process uses a constant temperature and humidity (e.g., controlling ambient humidity <30% and temperature set between 20°C and 25°C) inert atmosphere transport box with a built-in vibration-damping structure and a real-time environmental monitoring module. Temperature, humidity, and vibration data are wirelessly transmitted in real-time to ensure that the parts maintain the integrity of the weakened interface structure and a "zero-contamination" environment before entering the heat treatment and melt infiltration recovery processes. This achieves a precise, closed-loop protection system with full traceability and controllable status.

[0038] In another exemplary embodiment, step S400, which involves performing low-temperature heat treatment on the diamond-copper composite material part with precision machining characteristics to obtain a precision-machinable diamond-copper composite material final product, includes the following steps: S401: Multi-stage gradient heating treatment for diamond-copper composite parts; In this step, the diamond-copper composite part is placed in a high vacuum (≤10). -3In a heat treatment furnace under a dynamic inert atmosphere (high-purity argon, dew point ≤ -60℃), a three-step gradient heating method is used for heating treatment: First, the temperature is increased to 120℃ to 150℃ at a rate of 3℃ / min to 5℃ / min and held for 20min to allow adsorbed gases and residual lubricants to volatilize; then, the temperature is slowly increased to the lower limit of the melting range of the low-melting-point isolation layer material (such as Bi or Bi-Sn alloy) (approximately 140℃ to 160℃) at a rate of 1℃ / min to 2℃ / min, and held at this temperature for 30min to 60min to induce partial melting of the isolation layer but not complete flow; finally, the temperature is increased to the target temperature of 250℃ to 300℃ at a rate of 5℃ / min to 8℃ / min (adjusted according to the specific low-melting-point alloy composition, usually 20℃ to 50℃ higher than its melting point) to enter the main treatment stage.

[0039] The purpose of this application's three-step gradient heating method is to achieve controlled melting and migration of weakened interface layers (such as Bi or Bi-Sn alloys). Specifically, it includes: first, removing adsorbed gases and residual lubricants in a low-temperature range (120°C to 150°C) to prevent interference with interfacial reactions or the formation of porosity defects; then, triggering localized melting of the isolation layer in a slow heating range near the melting point (140°C to 160°C) while suppressing its overall flow, providing a buffer for the gradual softening of the interface layer and the release of internal stress; finally, completing the complete melting and capillary migration of the isolation layer in a rapid heating range above the melting point (250°C to 300°C), ensuring the thorough removal of the weakened interface while avoiding abnormal grain growth in the copper matrix or thermal stress concentration at the diamond-copper interface due to sudden temperature increases. This gradient heating strategy not only ensures the integrity and uniformity of weakened interface removal but also maximizes the maintenance of the microstructural stability of the composite material matrix, laying a clean and low-stress foundation for subsequent secondary melting and infiltration to achieve high-performance interface reconstruction.

[0040] S402: Pulse negative pressure extraction and surface adsorption of heated diamond-copper composite parts; In this step, during the main heat preservation stage at 250℃ to 300℃, the system periodically applies a pulsed negative pressure environment (e.g., at 1 atmosphere and 10) inside the furnace. -1 The frequency of Pa is alternated between 1Hz and 2Hz. The pressure difference drives the molten low-melting-point metal droplets to migrate to the surface along the micro-gap of the diamond-copper interface. At the same time, a porous zeolite or activated carbon fiber adsorption layer is arranged around the parts to selectively capture the volatilized metal vapors such as bismuth and tin, and prevent them from recondensing on the surface of the parts or contaminating the furnace.

[0041] S403: Interface purification of diamond-copper composite parts after pulse negative pressure extraction and surface adsorption; In this step, during the later stage of heat preservation, a trace amount of hydrogen gas (2% to 5% by volume) is introduced into the furnace to stimulate low-temperature hydrogen plasma (power density 50 W / m³). 2 Up to 200W / m 2 The temperature is kept ≤350℃. The reduction effect of hydrogen free radicals is used to remove trace oxides that may form at the interface and to promote the carbothermic reduction and volatilization of low melting point metal residues. The plasma treatment time is controlled between 10 min and 30 min to avoid overheating that could lead to recrystallization of the copper matrix or deformation of processing features.

[0042] S404: Cooling diamond-copper composite parts after interface purification.

[0043] In this step, after heat preservation and purification, the temperature is slowly cooled to below 80°C at a rate of 0.5°C / min to 1.0°C / min. This ultra-slow cooling process allows the interfacial micro-gaps to remain stable in an open state under the action of surface tension, avoiding premature closure due to thermal shrinkage, which would affect the subsequent backfilling of the molten copper. The entire cooling process is maintained in a vacuum or inert atmosphere to prevent oxidation.

[0044] In another exemplary embodiment, step S500, which involves performing melt infiltration treatment on the precision-machinable diamond-copper composite material final part to obtain a diamond-copper composite material part with reconstructed interfaces, includes the following steps: S501: Dual-temperature synergistic heating is used to melt and infiltrate precision-machinable diamond-copper composite material final parts; In this step, a precision-machinable diamond-copper composite material final part is placed in the main temperature zone within a dedicated melting and infiltration furnace, and heated to 1080°C to 1150°C at a rate of 5°C / min to 10°C / min. Simultaneously, the temperature of a secondary temperature zone containing a high-purity oxygen-free copper block (the melting and infiltration source) is independently controlled, ensuring it reaches above its melting point (approximately 1100°C to 1160°C) slightly later than the final material part. This creates a directional temperature gradient, driving the molten copper to continuously penetrate into the final material part along a decreasing temperature path. Furthermore, a dynamic micro-reducing atmosphere (such as an H2-Ar mixture with an H2 volume fraction of 3% to 8%) is continuously introduced into the furnace to simultaneously suppress oxidation and promote interfacial wetting of the final material part.

[0045] S502: In the initial stage of melting and infiltration, high-frequency ultrasonic vibration is applied to the copper liquid to assist in infiltration; In this step, high-frequency ultrasonic vibration (frequency 20 kHz to 40 kHz, power density 50 W / cm³) is immediately applied during the initial stage of copper melt infiltration. 2 Up to 150 W / cm 2The process utilizes cavitation to break up the interfacial gas film, thereby enhancing the wetting and spreading of the copper liquid on the nano gaps. Simultaneously, pulsed gas pressure (pressure from 0.1 MPa to 0.5 MPa, power from 0.5 Hz to 1.0 Hz) is applied, and the copper liquid is driven to penetrate deep into the three-dimensional interfacial network inside the material through periodic pressure fluctuations, thus achieving complete filling of high aspect ratio micro gaps.

[0046] S503: During the melting and infiltration heat preservation stage, a trace amount of Ti / Cr precursor vapor is introduced to cause an in-situ reaction at the tungsten carbide-copper liquid interface; In this step, during the melting and infiltration holding stage, a trace amount of Ti / Cr precursor vapor (concentration ≤500ppm) is introduced into the atmosphere to cause an in-situ reaction at the tungsten carbide-copper liquid interface, generating a nanocomposite transition layer (such as TiC-Cu) of a certain thickness (e.g., 5mm to 20 nm) to improve the interfacial bonding strength and thermal matching. Simultaneously, an axial static magnetic field (0.5T to 1.5T) is applied during the reaction process to accelerate atomic migration and defect healing using the magnetostrictive diffusion effect, and the temperature field uniformity is dynamically controlled (within ±5℃) using infrared thermography to avoid local overheating damage.

[0047] S504: Cooling and stress-relieving treatment is performed on the precision-machinable diamond-copper composite material final part after the in-situ reaction to obtain the diamond-copper composite material part after interface reconstruction.

[0048] In this step, after the melting and infiltration heat preservation is completed, this embodiment implements a three-stage graded cooling process to achieve interface structure locking and stress release of the final composite material part. Specifically, it includes: First, the final composite material part is cooled from the melting temperature to 900°C at a relatively fast cooling rate of 30°C / min to 50°C / min, which promotes the rapid solidification of the newly formed metallurgical bond at the interface, locks the microstructure, and inhibits abnormal grain growth; then, the temperature is further reduced to 500°C at a slow cooling rate of 2°C / min to 5°C / min. During this stage, the internal stress accumulated due to the thermal expansion difference of the heterogeneous materials is effectively released through a sufficient thermal relaxation process, avoiding the initiation of microcracks at the interface; finally, the active temperature control system is turned off, and the final composite material part is allowed to cool naturally to room temperature with the furnace to further equalize the residual stress distribution, and finally obtains a diamond-copper composite material part with residual stress ≤50 MPa, high dimensional stability, and no interface damage after interface reconstruction.

[0049] Below, this application verifies the superiority of the diamond-copper composite additive manufacturing method described in this application by comparing the experimental group and the control group. The experimental group (i.e., the method of this application) strictly followed the complete process flow of steps S100 to S500 of this application to prepare standard test parts (e.g., small blocks with precision mounting planes). The control group was set up as follows: The first group was the traditional melt infiltration method, in which Cr7C3 and copper layers were plated on the surface of diamond particles, and without selective laser melting (SLM) printing and interface weakening processes, green blanks of the same shape were directly obtained by cold pressing, followed by pressureless melt infiltration to obtain comparative samples; the second group was the direct machining method, in which fully densified diamond-copper composite material blocks were prepared using the aforementioned traditional melt infiltration method, and then polycrystalline diamond (PCD) tools were used to directly mill the surface to simulate the severe machining difficulties faced by high-hardness composite materials in the prior art.

[0050] Through the systematic comparison between the experimental group and the control group, it can be shown that compared with the traditional melt infiltration method, which has many interface defects and uneven performance, and the technical bottleneck of direct processing method, which is difficult to form precisely due to the hardness of the material, the additive manufacturing method based on "removable weakened interface" proposed in this application successfully achieves temporary machinability in local areas while maintaining the ultra-high thermal conductivity (720 W / m·K) and high electrical conductivity (92% IACS) of diamond-copper composite materials. This allows complex precision features (such as mounting surfaces and high-precision hole systems) to be completed efficiently through conventional machining. The interface performance is then fully restored and strengthened through subsequent heat treatment and melt infiltration processes, ultimately obtaining parts with high interface bonding strength (85 MPa), uniform performance, and excellent reliability. This systematically solves the key manufacturing problem of the difficulty in coordinating "forming-processing-performance" of high-performance diamond-copper composite materials.

[0051] Furthermore, this application provides performance comparison data between the experimental group and the control group, as shown in Table 1: Table 1

[0052] The data in Table 1 clearly demonstrate that, compared to the traditional infiltration method (control group A) and the direct processing method (control group B), the diamond-copper composite material prepared using the method of this application (experimental group) exhibits significant advantages in key properties. For example, the thermal conductivity is as high as 720 ± 15 W / m·K, the interfacial shear strength is increased to 85 ± 5 MPa, the volumetric conductivity reaches 92 ± 2 %IACS, and the hardness distribution is uniform (the processing recovery zone is consistent with the main body). The three-point bending strength reaches 480 ± 20 MPa. At the same time, the microstructure shows that the interface is continuous, dense, and defect-free, and the thermal conductivity retention rate after thermal cycling exceeds 98%. These findings comprehensively verify the breakthrough effect of this method in achieving a unified high performance, high reliability, and excellent machinability.

[0053] Figure 2 The metallographic morphology of diamond-copper composite materials prepared by conventional methods is shown. Figure 2 Obvious structural defects can be observed in the interface area: the bonding between the diamond particles and the copper matrix is ​​discontinuous, with unwetting gaps and pores visible in some areas. There is a clear mechanical contact boundary at the interface, and some particle edges show microcracks and interface peeling. This indicates that the interface bonding under traditional processes is mainly physical adhesion, with weak metallurgical bonding, which easily becomes a key area for stress concentration and increased thermal resistance.

[0054] Figure 3 The metallographic structure of the composite material prepared based on the method of this application is presented. Figure 3 It can show a significantly optimized interface structure: diamond particles are uniformly and densely wrapped by the copper matrix, the interface transition layer is continuous and without obvious pores or cracks; after low-temperature heat treatment and melt infiltration reconstruction, the original weakened interface region has formed a metallurgical bonding interface with gradient composition and nanocomposite structure, realizing tight bonding and good wetting between diamond-tungsten carbide-copper.

[0055] pass Figure 2 and Figure 3 The comparison fully demonstrates that this application, through the process route of "removable weakened interface - precision machining - interface reconstruction", not only achieves the machinability of complex structures, but also fundamentally improves the interface integrity of composite materials, providing key microstructure guarantees for obtaining diamond-copper composite materials with high thermal conductivity and high reliability.

[0056] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for additive manufacturing of diamond-copper composite materials, characterized in that, The method includes: Prepare composite materials that form weakened interfaces; Under the protection of an inert atmosphere, selective laser melting printing is performed on the composite material that forms the weakened interface to obtain a three-dimensional solid of the part to be processed with a processable transient region. Machining is performed on a three-dimensional solid of a part to be machined that has a machinable transient region to obtain a diamond-copper composite material part with precision machining characteristics; Low-temperature heat treatment is performed on diamond-copper composite parts with precision machining characteristics to obtain precision-machinable diamond-copper composite final parts. A precision-machinable diamond-copper composite material final part is subjected to melt infiltration treatment to obtain a diamond-copper composite material part with reconstructed interface.

2. The method according to claim 1, characterized in that, The preparation of the composite material that forms a weakened interface includes: Pre-treatment of diamond particles; A tungsten carbide layer is coated on the surface of the pretreated diamond particles to obtain a matrix interface layer; A dense copper layer is deposited on the substrate interface layer; A low-melting-point insulating layer is coated onto the surface of copper-plated diamond particles to obtain a composite material containing a removable weakened interface.

3. The method according to claim 2, characterized in that, The pretreatment of diamond particles includes: Clean the diamond particles; Etching is performed on the surface of the cleaned diamond particles; Activation treatment is performed on the etched diamond particles; Titanium or chromium metal layers are deposited on the surface of activated diamond particles.

4. The method according to claim 2, characterized in that, The process of coating the surface of pretreated diamond particles with a tungsten carbide layer to obtain a matrix interface layer includes: An amorphous carbon-tungsten transition layer is deposited on the surface of pretreated diamond particles in a mixed atmosphere of tungsten-containing organic precursor and methane. Tungsten carbide layers are epitaxially grown on the surface of an amorphous carbon-tungsten transition layer in a mixed atmosphere of tungsten halides and hydrocarbons.

5. The method according to claim 1, characterized in that, The selective laser melting printing of the composite material forming the weakened interface, performed under an inert atmosphere, to obtain a three-dimensional solid of the part to be processed with a machinable transient region, includes: In selective laser melting equipment, composite materials that form weakened interfaces are spread on a preheated powder-coated substrate; Differentiated printing is performed on the composite materials that have been laid out to form a weakened interface; Repeat the above steps until the 3D structure of the part is printed, obtaining a 3D solid of the part to be processed that is generally dense and has weakened interfaces in some areas.

6. The method according to claim 5, characterized in that, The process of differentially printing the laid composite material that forms a weakened interface includes: For the main body area of ​​the part in the composite material, high energy density parameters are used for printing; For the processable transient region in the composite material, low energy density parameters are used for printing.

7. The method according to claim 1, characterized in that, The process of machining a three-dimensional solid of a part having a machinable transient region to obtain a diamond-copper composite material part with precision machining characteristics includes: Clamping and positioning of a three-dimensional solid part with a machinable transient region; Set the machining parameters; The clamped 3D solid is processed step by step according to the set processing parameters; Perform transient protection and sequence transfer on the completed 3D solid.

8. The method according to claim 1, characterized in that, The method of performing low-temperature heat treatment on diamond-copper composite material parts with precision machining characteristics to obtain precision-machinable diamond-copper composite material final parts includes: Heating treatment is applied to diamond-copper composite material parts. Pulse negative pressure extraction and surface adsorption were performed on diamond-copper composite parts after heating. Interface purification of diamond-copper composite parts after pulse negative pressure extraction and surface adsorption; The diamond-copper composite parts after interface purification are cooled.

9. The method according to claim 8, characterized in that, The heating treatment of the diamond-copper composite material parts includes: Diamond-copper composite parts are heated by multi-stage gradient heating.

10. The method according to claim 1, characterized in that, The process of performing melt infiltration treatment on precision-machinable diamond-copper composite material final parts to obtain diamond-copper composite material parts with reconstructed interfaces includes: Dual-temperature synergistic heating is used to melt-infiltrate precision-machinable diamond-copper composite material final parts; In the initial stage of melting and infiltration, auxiliary infiltration is performed on the molten copper; During the melting and infiltration heat preservation stage, a trace amount of Ti / Cr precursor vapor is introduced to undergo an in-situ reaction at the tungsten carbide-copper liquid interface. Cooling and stress-relieving treatments are performed on precision-machinable diamond-copper composite parts that have undergone in-situ reactions to obtain diamond-copper composite parts with reconstructed interfaces.

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