A method for preparing a reinforced copper-based composite material with continuous distribution of reinforcement phase

Abstract

This invention discloses a method for preparing a copper-based composite material with a spatially continuous distribution of reinforcing phase. The method includes: step 1, cleaning and roughening the surface of the reinforcing phase fibers to obtain pretreated fibers; step 2, preparing a spatially continuous structure of copper and pretreated fibers to construct a three-dimensional continuous mesh structure; and step 3, densifying the three-dimensional continuous mesh structure to obtain the composite material. Through the interconnected network framework of the reinforcing phase and copper, the method effectively solves problems such as broken thermal conduction paths, interface debonding, and insufficient high-temperature strength in traditional composite materials, significantly improving the thermal conductivity, mechanical properties, and thermal stability of the material, making it suitable for extreme service environments such as high-heat-load divertors.

Description

Technical Field

[0001] This invention belongs to the field of composite material structures for heat dissipation systems of controlled nuclear fusion divertors, and relates to a method for preparing a copper-based composite material with a continuously distributed phase space reinforcement. Background Technology

[0002] Controlled nuclear fusion, as a crucial direction for the development of future clean energy, relies heavily on its core component, the divertor, which must withstand extreme operating conditions, including steady-state heat loads as high as 10-20 MW / m² and high-flux neutron irradiation. The water-cooled heat sink module in the divertor is typically made of copper-based composite materials due to their excellent thermal conductivity and certain mechanical strength. However, under high-temperature and high-irradiation environments, traditional copper-based composite materials face severe challenges: significantly reduced mechanical strength at high temperatures, degradation of thermal conductivity, interfacial cracking caused by thermal expansion mismatch, and even coolant leakage, threatening the safe operation of the reactor.

[0003] Currently, commercial copper-based composite heat sink materials are mainly prepared through traditional processes such as powder metallurgy, mechanical alloying, stirring casting, or ball milling. These methods generally suffer from the following technical bottlenecks: (1) Uneven distribution of reinforcing phase: The reinforcing phases introduced (such as tungsten particles, silicon carbide short fibers, oxide dispersions, etc.) are mostly in low-dimensional dispersion (granular, short fiber or sheet-like), which are prone to agglomeration in the copper matrix, resulting in uneven structure; (2) Poor interface bonding: The wettability between the reinforcing phase and the copper matrix is ​​poor, the interface bonding strength is low, and it is easy to debond under thermal cycling or load, forming micropores or cracks; (3) Broken thermal conduction path: Due to the agglomeration of the reinforcing phase and the presence of pore defects, the migration path of free electrons in the copper matrix is ​​severely hindered, resulting in the overall thermal conductivity being significantly lower than theoretically expected; (4) High temperature performance degradation: The copper matrix softens at high temperature, and the traditional dispersion reinforcement structure cannot effectively transfer and bear the load, resulting in a sharp deterioration of the high temperature mechanical properties of the composite material; (5) Insufficient irradiation stability: Under high dose neutron irradiation, the accumulation of lattice defects and interface degradation further exacerbate the degradation of material performance.

[0004] The aforementioned problems make it difficult for existing copper-based composite materials to simultaneously meet multiple performance requirements such as high thermal conductivity, high strength, good thermal matching, and long-term irradiation stability, which severely restricts the application of divertors in high-power fusion devices.

[0005] Therefore, there is an urgent need to develop a novel method for preparing copper-based composite materials. By optimizing the spatial configuration and interfacial properties of the reinforcing phase, a continuous interpenetrating network structure between the reinforcing phase and the copper matrix in three-dimensional space can be achieved, thereby synergistically improving the high-temperature mechanical properties, thermal conductivity, and thermal stability of the material, and providing a high-performance heat sink material solution for controlled nuclear fusion divertors. Summary of the Invention

[0006] To overcome the above problems, this invention proposes a method for preparing a copper-based composite material with a spatially continuous reinforced phase. The method includes: Step 1, cleaning and roughening the surface of the reinforcing phase fibers to obtain pretreated fibers; Step 2, preparing a spatially continuous structure between copper and the pretreated fibers to construct a three-dimensional continuous mesh structure; Step 3, densifying the three-dimensional continuous mesh structure to obtain the composite material. Through the interconnected network framework of the reinforcing phase and copper, the method effectively solves problems such as broken thermal conduction paths, interface debonding, and insufficient high-temperature strength in traditional composite materials, significantly improving the thermal conductivity, mechanical properties, and thermal stability of the material, making it suitable for extreme service environments such as high-heat-load divertors.

[0007] Specifically, the object of the present invention is to provide the following aspects:

[0008] On the one hand, a method for preparing a copper-based composite material with a continuously distributed phase space is provided, the method comprising:

[0009] Step 1: Clean and roughen the surface of the reinforcing phase fiber to obtain pretreated fiber;

[0010] Step 2: Prepare a spatially continuous structure of copper and pretreated fibers to construct a three-dimensional continuous mesh structure;

[0011] Step 3: The three-dimensional continuous mesh structure is densified to obtain the composite material;

[0012] In step 1, the reinforcing phase fiber is any one of metal fiber, metal oxide fiber, metal nitride fiber, and carbon fiber.

[0013] In step 1, the diameter of the reinforcing phase fiber is 100-500 μm.

[0014] In step 1, the cleaning includes alkaline washing and acid washing. The alkaline washing is used to remove oil from the surface of the reinforcing phase fiber, and the acid washing is used to remove the oxide layer from the surface of the reinforcing phase fiber.

[0015] In step 2, the copper is introduced by means of interfacial composition control.

[0016] Optionally, the interface component regulation refers to introducing a copper coating layer on the surface of the pretreated fiber, wherein the copper coating layer and the pretreated fiber form a composite fiber with a coaxial structure.

[0017] In step 2, the copper is introduced through a co-weaving process with pretreated fibers.

[0018] In step 2, the copper is introduced through melt infiltration after the reinforcing phase fibers are woven into a skeleton.

[0019] In step 3, the densification process is cold rolling or hot isostatic pressing.

[0020] In a second aspect, a composite material prepared by the method described in the first aspect is provided, wherein the copper volume fraction is 70%-95%.

[0021] The beneficial effects of this invention include:

[0022] (1) The method provided by the present invention constructs a spatial continuous grid of the reinforcing phase and combines melting, electroplating and densification processes to achieve high density filling of copper and the reinforcing phase, effectively avoiding the problem of thermal path breakage caused by the agglomeration of the reinforcing phase, sintering pores and interface debonding, and achieving synergistic improvement of mechanical properties and thermal conductivity.

[0023] (2) The method provided by the present invention relies on the spatial continuous grid of the reinforcing phase to enable the load of copper-based composite material to be continuously transmitted, avoiding the stress transmission failure problem caused by the high temperature softening of copper, and greatly enhancing the high temperature mechanical strength of the composite material.

[0024] (3) The method provided by the present invention, by adjusting the braiding structure, copper volume fraction and copper introduction method, designs the relative content and spatial configuration of copper and reinforcing phase within a wide range, thereby achieving a synergistic improvement in high-temperature thermal conductivity, mechanical strength and thermal stability, and improving the long-term safe service capability of copper-based composite heat sink materials in divertors. Attached Figure Description

[0025] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0026] In the attached diagram:

[0027] Figure 1 The three-dimensional continuous mesh structure obtained in Example 1 is shown;

[0028] Figure 2 A macroscopic diagram of the composite material obtained in Example 1 is shown;

[0029] Figure 3 The three-dimensional continuous mesh structure obtained in Example 2 is shown;

[0030] Figure 4 A macroscopic diagram of the composite material obtained in Example 2 is shown;

[0031] Figure 5The three-dimensional continuous mesh structure obtained in Example 3 is shown;

[0032] Figure 6 A macroscopic diagram of the composite material obtained in Example 3 is shown;

[0033] Figure 7 One of the SEM images of the copper-coated tungsten fiber coaxial composite fiber prepared in Example 4 is shown.

[0034] Figure 8 This is the second SEM image of the copper-coated tungsten fiber coaxial composite fiber prepared in Example 4;

[0035] Figure 9 The image shows a SEM image of the three-dimensional continuous mesh structure obtained in Example 4;

[0036] Figure 10 The SEM image of the composite material obtained in Example 4 is shown. Detailed Implementation

[0037] The following will refer to the appendix. Figures 1 to 10 Specific embodiments of the invention will be described in more detail below. While specific embodiments of the invention are shown in the accompanying drawings, it should be understood that the invention 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 the invention and to fully convey the scope of the invention to those skilled in the art.

[0038] 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 are preferred embodiments for carrying out the invention; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of the invention. The scope of protection of this invention is determined by the appended claims.

[0039] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship in the working state of this invention, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0040] To facilitate understanding of the embodiments of the present invention, further explanations and descriptions will be provided below with reference to the accompanying drawings and specific embodiments. The accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0041] In a first aspect, according to the present invention, a method for preparing a copper-based composite material with a continuously distributed phase space is provided, the method comprising:

[0042] Step 1: Clean and roughen the surface of the reinforcing phase fiber to obtain pretreated fiber;

[0043] Step 2: Prepare a spatially continuous structure of copper and pretreated fibers to construct a three-dimensional continuous mesh structure;

[0044] Step 3: The three-dimensional continuous mesh structure is densified to obtain the composite material.

[0045] The above methods will be described in detail below.

[0046] Step 1: Clean and roughen the surface of the reinforcing phase fiber to obtain pretreated fiber.

[0047] In step 1, organic contaminants, oxide layers and other impurities on the surface of the reinforcing phase fiber are removed, and a rough surface with a micro-anchoring structure is constructed to provide a clean and highly active substrate for subsequent interface control, thereby significantly improving the wettability, interfacial bonding strength and thermal conductivity between the copper matrix and the reinforcing phase.

[0048] In step 1, the reinforcing phase fiber can be a metal fiber such as tungsten fiber, tantalum fiber, niobium fiber, molybdenum fiber, or nickel fiber; it can also be a metal oxide fiber such as cerium oxide fiber, lanthanum oxide fiber, or zirconium oxide fiber; or a metal nitride fiber such as silicon nitride fiber or aluminum nitride fiber; or carbon fiber. Preferably, the reinforcing phase fiber is a metal fiber; more preferably, the reinforcing phase fiber is a tungsten fiber or tantalum fiber.

[0049] Among them, metal fibers have high thermal conductivity, and in composite materials, they not only bear loads but also serve as auxiliary heat conduction channels. Tungsten fibers, in particular, have an ultra-high melting point; both the International Thermonuclear Experimental Reactor (ITER) and China use tungsten / copper as plasma-facing materials in divertors, demonstrating high technological maturity. Tantalum fibers show almost no oxidation or corrosion in high-temperature steam and coolant environments, making them particularly suitable for long-term operation of water-cooled modules; they also possess good ductility.

[0050] In step 1, the diameter of the reinforcing phase fiber is 100-500 μm, preferably 100-200 μm, such as 100 μm tungsten fiber or 200 μm tantalum fiber. The constraint for selecting this parameter is that as the diameter of the reinforcing phase fiber increases, the specific surface area is larger, which is beneficial to interfacial bonding. However, an excessively large diameter leads to a sharp decrease in flexibility, making three-dimensional weaving difficult and easily causing local stress concentration, which can become a crack initiation source under thermal cycling or mechanical loading.

[0051] In step 1, the cleaning includes alkaline washing and acid washing, preferably, alkaline washing and acid washing in sequence.

[0052] The alkaline washing process includes: using an aqueous sodium hydroxide solution with a mass concentration of 30-70 g / L to remove oil at 82-95°C for 10-15 min, followed by washing with deionized water and drying with hot air.

[0053] In one embodiment, the alkaline washing comprises: using an aqueous sodium hydroxide solution with a mass concentration of 50 g / L to remove oil at 90°C for 15 min, followed by washing with deionized water until neutral, and then drying with hot air.

[0054] In this invention, during the preparation, drawing, winding, and storage of the reinforcing phase fiber, organic contaminants inevitably adsorb onto its surface, mainly including grease, lubricating oil, release agents, fingerprint residue, and organic components from environmental dust. These contaminants are hydrophobic and have low surface energy, which severely hinders the subsequent wetting and adhesion of the copper matrix on the fiber surface, leading to poor interfacial bonding, increased porosity, and even interfacial debonding. Sodium hydroxide solution effectively removes the above-mentioned organic contaminants through saponification and emulsification.

[0055] Furthermore, the constraints for selecting a sodium hydroxide aqueous solution of 30-70 g / L are as follows: Too low a concentration results in insufficient alkalinity, a slow saponification reaction rate, and difficulty in thoroughly removing stubborn oil stains, especially high-viscosity greases or aged oil films, leading to poor cleaning effects; too high a concentration, while enhancing detergency, may cause excessive corrosion to certain reinforcing phase materials (such as tungsten fibers containing small amounts of impurities or ceramic fibers with microcracks on the surface), even triggering surface grain boundary erosion or hydrogen embrittlement; simultaneously, high-concentration alkaline solutions easily leave crystal residues on the fiber surface, increasing the difficulty of subsequent water washing. A concentration range of 30-70 g / L is suitable for most refractory metal fibers (W, Ta, Mo, Nb) and some silicon carbide, alumina, and other ceramic fibers, demonstrating good versatility. A temperature of 82-95°C effectively accelerates the saponification reaction, ensuring that stubborn oil stains are thoroughly removed within 10-15 minutes.

[0056] Furthermore, after alkaline washing, NaOH, saponification products, and dissolved organic salts remain on the fiber surface. If not removed, these residues will react with H+ during subsequent acid washing. +Reactions can produce precipitates (such as metal hydroxides) or decompose to generate gases during high-temperature processing, leading to interfacial defects. Therefore, it is necessary to rinse with deionized water multiple times (usually 3–5 times) until the pH of the wash solution is close to neutral (pH = 6–8) to ensure that no ions remain on the surface.

[0057] Furthermore, hot air drying completely removes physically adsorbed water in a short time (usually 1-2 hours).

[0058] In step 1, the pickling includes: immersing in a 5%-15% dilute nitric acid aqueous solution at room temperature for 10-20 minutes, followed by rinsing with alcohol and deionized water and drying with hot air.

[0059] In one embodiment, the pickling includes: immersing in a 10% (w / w) dilute nitric acid aqueous solution at room temperature for 15 min, followed by rinsing with alcohol and deionized water until neutral, and then drying with hot air.

[0060] In this invention, although alkaline washing can effectively remove organic contaminants, refractory metal-reinforced fibers (such as tungsten, tantalum, and molybdenum) readily form dense surface oxide layers in air, such as WO3, Ta2O5, and MoO3. These oxides have large wetting angles with the copper substrate, severely hindering the spread of copper liquid or copper plating on their surface; and they easily induce interfacial stress concentration during thermal cycling, leading to the initiation of microcracks. Nitric acid, as a strong oxidizing acid, efficiently removes the aforementioned oxide films. Taking tungsten fibers as an example, HNO3 reacts with surface WO3 to generate soluble tungstic acid (H2WO4) or tungsten nitrate complexes; for tantalum fibers, dilute nitric acid slowly dissolves Ta2O5, especially when microscopic defects or grain boundaries exist on the surface. + It penetrates along the channel and gradually peels off the oxide layer.

[0061] Furthermore, the constraint condition for selecting a 5%-15% dilute nitric acid aqueous solution is: H + Insufficient concentration results in a slow oxide dissolution rate, making it difficult to completely remove dense oxide layers, especially for thick oxide films (such as long-stored tungsten wires). Excessive concentration leads to over-oxidation of metals such as tungsten, generating volatile high-valence oxides (such as WO3 sublimation), causing abnormally increased surface roughness or even pitting corrosion. Alternatively, it may cause tantalum and niobium to develop surface micropores or hydrogen embrittlement risks in high-concentration nitric acid.

[0062] Furthermore, after pickling, nitrate ions (NO3) adhere to the fiber surface. - ), metal ions (W) 6+ Ta 5+ (etc.) and reaction byproducts. If not removed, residual NO3 will remain. - NO may be produced during subsequent high-temperature processing. xGases can induce internal pores; metal ions may redeposit as hydroxides if water washing is insufficient, forming new contaminants. Therefore, it is essential to first use alcohol, followed by ultrasonic rinsing with deionized water 3-5 times until the pH of the washing solution reaches 6-7, ensuring ion-level cleanliness. Hot air drying is then performed to prevent residual moisture from causing secondary oxidation (especially for highly reactive metals such as tantalum and niobium).

[0063] In step 1, the surface roughening treatment includes at least one of mechanical sandblasting, laser texturing, acid-base etching, two-step chemical reconstruction, chelation modification, or physical and chemical vapor deposition, preferably acid-base etching.

[0064] In one embodiment, tungsten fibers are etched using a weak base-silicate synergistic etching process. Preferably, a mixed solution of 2-5 wt% sodium hydroxide and 5-10 g / L sodium silicate is used, and the solution is treated at room temperature for 10-30 min. During this process, NaOH provides a weakly alkaline environment, selectively dissolving impurity phases or micro-oxidized regions at the tungsten grain boundaries. Sodium silicate acts as a corrosion inhibitor and complexing agent, suppressing excessive dissolution of the tungsten bulk. Simultaneously, its hydrolysis products can form a transient silica film on the surface, guiding non-uniform etching and promoting the formation of nanoscale steps and micropores. Excessive NaOH concentration will accelerate overall tungsten corrosion, leading to surface peeling; insufficient NaOH concentration will result in insufficient etching kinetics. Too little sodium silicate will result in insufficient corrosion inhibition, while too much will completely passivate the surface, losing its roughening effect.

[0065] In one embodiment, tantalum fibers are etched using a strong acid, preferably a 30-50 vol% hydrofluoric acid aqueous solution, treated at room temperature for 5-15 minutes, for example, a 40 vol% hydrofluoric acid aqueous solution treated at room temperature for 10 minutes. During this process, HF dissolves the Ta₂O₅ oxide film on the tantalum surface and lightly etches the tantalum metal body, forming micron-sized trenches and island-like protrusions, significantly improving the surface anchoring effect. When the HF concentration is below 30%, the etching rate is too slow, making it difficult to form effective roughness; above 50%, it easily leads to over-corrosion and may even cause hydrogen embrittlement (due to atomic hydrogen generated by HF reduction penetrating into the metal).

[0066] Step 2: Prepare a spatial continuous structure of copper and pretreated fibers to construct a three-dimensional continuous mesh structure.

[0067] In step 2, the copper is copper sheet, copper block or copper fiber with a purity of ≥99.5%.

[0068] In step 2, the copper is introduced in any of the following ways: (a) by blending and weaving with pretreated fibers; (b) by introducing through interfacial component control; or (c) by introducing through melt infiltration after the reinforcing phase fibers are woven into a skeleton.

[0069] In one embodiment, copper is blended and woven with pretreated fibers. In this case, the copper has a purity of ≥99.5% and its diameter is preferably the same as that of the reinforcing phase fiber, which facilitates the obtaining of bundled weaving with excellent mechanical properties.

[0070] At this point, copper fibers and pretreated fibers are bundled together at a volume ratio of 8:1 to 16:1 to form a composite fiber bundle. This composite fiber bundle is then introduced into a three-dimensional loom, employing four-way, five-way, or 2.5D weaving techniques to construct a three-dimensional continuous mesh structure. The surface weaving angle of the constructed three-dimensional continuous mesh structure is 32-40°. This angle range ensures axial mechanical properties while improving transverse strength and shear resistance, and promotes the formation of a uniform, interconnected copper network in three-dimensional space. For example, a five-way structure formed by weaving copper fibers and tungsten fibers at a volume ratio of 10:1 has a surface weaving angle of 39.3°; a four-way structure has an angle of 32.2°.

[0071] Furthermore, copper fibers are bundled with pretreated fibers at a volume ratio of 8:1 to 16:1, corresponding to a copper volume fraction of 70%-95% after densification, which balances high thermal conductivity and high electrical conductivity. If the ratio is lower than 8:1, the thermal conductivity and / or electrical conductivity are insufficient, and it is difficult to form a continuous copper matrix; if it is higher than 16:1, the content of the reinforcing phase fiber is too low, and the strength improvement efficiency is significantly reduced.

[0072] In one embodiment, copper is introduced through interfacial component control, that is, copper is pre-coated onto the surface of pretreated fibers to form coaxial composite fibers, which are then woven. The interfacial component control refers to introducing a copper coating layer onto the surface of the pretreated fibers, forming a coaxial composite fiber with the pretreated fibers, thereby improving the chemical compatibility between the reinforcing phase fibers and the copper matrix. The interfacial component control is selected from any one of electroplating, electroless plating, or magnetron sputtering.

[0073] Preferably, a copper coating layer with a thickness of 1-50 μm is coated onto the surface of the pretreated fibers by electroplating. These copper coating layers interconnect during the subsequent densification process, forming a continuous copper matrix in the composite material, achieving a spatially co-continuous distribution of the reinforcing phase fibers and the copper matrix.

[0074] The constraints for the 1-50μm copper cladding parameters are as follows: if the copper cladding is too thin, although it can improve wettability, it cannot completely cover the micropores or rough peaks and valleys on the fiber surface, resulting in a "pinhole effect". In subsequent weaving, hot pressing or high-temperature treatment, it is easy to cause local cracking or oxidation, losing its protective / transition function; if the copper cladding is too thick, it will lead to significant accumulation of internal stress, which is prone to microcracks, peeling or flaking, especially on curved fibers, and in thermal cycling, the CTE mismatch with tungsten will cause interface warping or blistering.

[0075] Furthermore, tungsten fibers are placed in an electroplating solution, with pretreated tungsten fibers as the cathode and copper sheets as the anode. The current density is controlled at 0.5-2 A / dm², and electroplating is performed at 20-35℃ for 5-10 min. Copper ions are driven to migrate directionally to the surface of the tungsten fibers by an external power source and continuously thicken, forming a copper coating layer with a thickness of 1-50 μm that is tightly bonded to the tungsten fibers. This yields a copper-coated tungsten fiber coaxial composite fiber, thus achieving interface composition control.

[0076] The electroplating solution is a mixture of copper sulfate (180-220 g / L) and sulfuric acid (50-70 g / L). The copper sulfate concentration of 180-220 g / L provides a sufficient copper ion source to support a high deposition rate; the sulfuric acid concentration of 50-70 g / L is used to improve the solution's conductivity and inhibit anolyte passivation. The sulfuric acid concentration cannot be too low, otherwise it will easily lead to anolyte passivation; nor can it be too high, as it will cause corrosion of the equipment or increase the internal stress of the coating. The synergistic effect of these two components results in a dense, low-porosity copper coating, laying the interfacial foundation for the high thermal conductivity and high strength of subsequent composite materials.

[0077] Furthermore, the constraints for a current density of 0.5-2 A / dm² are: too slow a deposition rate (<0.5 μm / min) results in low production efficiency, making it unsuitable for industrial application, and it is susceptible to impurity interference at low currents; exceeding the limiting current density (>2 A / dm²) for Cu... 2+ Rapid depletion at the cathode surface leads to severe concentration polarization, causing the copper coating to char and even exacerbating hydrogen evolution side reactions: 2H + + 2e - → H2↑, causing hydrogen embrittlement.

[0078] Furthermore, the electroplating time is positively correlated with the thickness of the copper cladding layer.

[0079] During weaving, the coaxial composite fibers are introduced into a three-dimensional loom to form a three-dimensional continuous mesh structure with a porosity controlled at 75%-80%. This porosity range ensures that the copper has sufficient deformation space to achieve full densification during the subsequent densification process, while avoiding fiber breakage or interface peeling due to excessively high initial density.

[0080] In one embodiment, the pretreated fibers are woven into a skeleton and then introduced through melt infiltration. Specifically: the pretreated fibers are woven into a four-dimensional, five-dimensional, or 2.5D skeleton using a three-dimensional loom, and then treated at high temperature to obtain a fiber frame; copper blocks are laid on the surface of the fiber frame, and then vacuum melt infiltrate in a vacuum melt infiltration furnace, allowing the liquid copper to spontaneously infiltrate into the pores of the skeleton by capillary action, and after cooling, a three-dimensional continuous mesh structure is obtained.

[0081] Preferably, tantalum fibers are woven into a 2.5D skeleton using a three-dimensional loom. The porosity of the skeleton is controlled at 70%-75% to ensure sufficient copper immersion and to guarantee the strengthening effect of the tantalum fibers on the copper matrix. Subsequently, the skeleton is heated in nitrogen at 350-450℃ for 1-3 hours to complete the high-temperature treatment and obtain a fiber frame. Next, copper blocks of (50-70) mm × (50-70) × (10-20) mm are laid on the surface of the fiber frame. In a vacuum melting furnace, the temperature is increased from room temperature to 1100-1400℃ at a heating rate of 5-10℃ / min under vacuum and held for 30-60 minutes. Under these conditions, the liquid copper spontaneously infiltrates into the three-dimensional interconnected pore network of the fiber frame under capillary action, achieving self-filling. After cooling, a three-dimensional continuous mesh structure is obtained.

[0082] Furthermore, the high-temperature treatment aims to remove trace amounts of lubricating oil, moisture, or organic residues adsorbed on the surface of the tantalum fibers during the weaving process. The temperature should not be lower than 350℃, otherwise the organic matter will not decompose completely; it should not exceed 450℃ to avoid premature recrystallization or surface oxidation of the tantalum, and to prevent fiber embrittlement. The skeleton after impurity removal is called the "fiber frame." Copper is cut into copper blocks to shorten the melting time and improve the uniformity of impregnation. The mold containing the fiber frame and copper blocks is placed as a whole into a vacuum infiltration furnace, and a vacuum of ≤10℃ is applied. -2 Pa is used to maximize the removal of oxygen and water vapor, preventing copper from oxidizing to Cu2O at high temperatures.

[0083] Furthermore, the constraints for the melting and infiltration temperature of 1100-1400℃ are: this temperature is higher than the melting point of copper to ensure sufficient fluidity of the copper; but it does not exceed 1400℃ to prevent excessive interfacial reaction between the strengthening phase and copper, which could generate a brittle phase; the constraints for the holding time of 30-60 min are: if the time is too short, the copper will not fully fill the micropores; if the time is too long, energy consumption will increase and may cause grain coarsening; the constraints for the heating rate of 5-10℃ / min are: to avoid rapid heating that could cause the copper block to boil over or the skeleton to crack due to thermal stress. The ambient temperature is typically 10-40℃.

[0084] Step 3: The three-dimensional continuous mesh structure is densified to obtain the composite material.

[0085] In step 3, a densification process is performed to eliminate residual porosity, improve interfacial bonding strength, and achieve a near-fully dense structure. After densification, the copper volume fraction is 70%-95%, and the copper forms a highly interconnected network. The densification process is performed by cold rolling or hot isostatic pressing.

[0086] Taking cold rolling as an example, a three-dimensional continuous grid structure is placed in a cold rolling mill and rolled in multiple passes at room temperature (20-25℃). The first pass has a reduction rate of 10-20%, and the subsequent passes have a reduction rate of 5-10%, with a total cumulative reduction rate of 60-75%. The interval between passes does not exceed 5 minutes. Stress is relieved by vacuum annealing at 800-950℃ during the interval between passes.

[0087] The constraint condition of selecting the first pass reduction rate of 10-20% is as follows: the first pass needs to provide sufficient deformation to achieve plastic flow and densification of the copper matrix. If the reduction rate is too low, it will not be enough to eliminate porosity and improve interfacial bonding; if the reduction rate is too high, it will cause the fiber and matrix deformation to be inconsistent, leading to edge cracking or fiber breakage.

[0088] The constraint condition of selecting a reduction rate of 5-10% for subsequent passes is as follows: After the large deformation of the first pass, the material is severely work hardened, and it is necessary to reduce the single-pass reduction rate to prevent excessive stress concentration. Multi-pass rolling with a small reduction rate is conducive to uniform strain distribution and promotes the gradual advancement of the densification process.

[0089] The constraint of selecting a total cumulative reduction rate of 60-75% is as follows: this reduction rate range can ensure that the relative density of the composite material reaches more than 99%, while avoiding fiber breakage caused by excessive deformation. When the reduction rate is less than 60%, the residual porosity is too high; when the reduction rate exceeds 75%, the reinforcing phase particles break significantly, and the interface integrity decreases.

[0090] The constraint of selecting the above-mentioned interval time not exceeding 5 minutes is as follows: a short interval time can utilize the deformation heat generated by the previous rolling pass, reduce the material deformation resistance, improve the machinability of subsequent passes, and at the same time avoid surface oxidation caused by long time intervals, ensuring interface cleanliness.

[0091] Taking hot isostatic pressing as an example, a three-dimensional continuous mesh structure is encapsulated in a vacuum stainless steel sheath (vacuum degree ≤10). -1 The material is placed in a hot isostatic pressing (HIP) apparatus and held at 750-850℃ and 100-150 MPa for 2-4 hours. The constraint of 750-850℃ is chosen because this temperature is higher than the recrystallization temperature and significant diffusion temperature of copper, promoting pore spheroidization and closure, but lower than the melting point of copper and the temperature at which the strengthening phase / copper interface reaction is intense, avoiding the formation of brittle phases or excessive fiber grain growth. The constraint of 100-150 MPa is chosen because too low a pressure is insufficient to drive pore collapse; too high a pressure drastically increases the requirements of the equipment and may crush the woven structure. The constraint of 2-4 hours of holding time is chosen to ensure that heat and pressure are uniformly transferred to the interior of the three-dimensional continuous mesh structure, achieving overall densification.

[0092] Secondly, according to the present invention, a composite material prepared by the method described in the first aspect is provided, wherein the composite material is made of reinforcing phase fibers woven into a spatial continuous mesh as a load-bearing skeleton; the copper matrix fills the pores of the continuous mesh skeleton and is tightly bonded to the reinforcing phase fibers to form a spatially interpenetrating continuous network of copper and reinforcing phase, wherein the volume fraction of copper is 70%-95%; the composite material has an axial elastic modulus of 120-130 GPa at 500℃, a tensile strength of 130-140 MPa, and an axial high-temperature thermal conductivity of 340-350 W·m. -1 ·K -1 .

[0093] Example

[0094] The present invention is further described below through specific examples; however, these examples are merely exemplary and do not constitute any limitation on the scope of protection of the present invention.

[0095] Example 1

[0096] A method for preparing copper-based composite materials with continuous distribution of tungsten fibers in a three-dimensional four-way braided structure.

[0097] (1) Tungsten fiber with a diameter of 100 μm was treated as follows: First, it was washed with 50 g / L sodium hydroxide aqueous solution at 90°C for 15 min to remove oil. Then it was washed with deionized water until neutral and dried with hot air. Next, it was soaked in 10% dilute nitric acid solution at room temperature for 15 min to remove the oxide layer on the surface of the tungsten fiber. Then it was washed with alcohol and deionized water until neutral and dried with hot air. Finally, the surface of the tungsten fiber was roughened with a mixed solution of sodium hydroxide (5wt%) and sodium silicate (8g / L) for 20 min. After rinsing with deionized water several times, the pretreated fiber was obtained.

[0098] (2) The pretreated fiber and 100μm copper fiber are bundled together at a volume ratio of 1:10 to form a composite fiber bundle; then the composite fiber bundle is introduced into a three-dimensional loom and a four-way weaving process is adopted to construct a three-dimensional continuous grid structure with a surface weaving angle of 32.2°. Figure 1 The diagram shows a three-dimensional continuous grid structure, in which the bundled yarns are interwoven evenly and regularly, without obvious bending, twisting or loosening, and the yarns form a continuous three-dimensional reinforcing phase structure.

[0099] (3) Encapsulate the three-dimensional continuous mesh structure in a vacuum stainless steel sheath (vacuum degree ≤10). -1 The copper was placed in a hot isostatic pressing apparatus and kept at 850℃ and 150MPa for 3 hours to fully densify the copper, resulting in a three-dimensional four-way braided tungsten fiber continuously distributed reinforced copper-based composite material with a copper volume fraction of 91% after densification. Figure 2The macroscopic image of the prepared composite material is shown, which shows that the copper matrix and the reinforcing phase skeleton are tightly bonded together, and no obvious pores or cracks are observed.

[0100] Through high-temperature tensile testing, the obtained three-dimensional four-way braided tungsten fiber continuously distributed reinforced copper matrix composite material exhibits an axial high-temperature elastic modulus of 122 GPa and a high-temperature tensile strength of 137 MPa at 500℃. Through high-temperature thermal conductivity testing at 500℃, the axial high-temperature thermal conductivity of the obtained three-dimensional four-way braided tungsten fiber continuously distributed reinforced copper matrix composite material is 344 W·m. -1 ·K -1 The prepared composite material has a lower elastic modulus (98 GPa) and thermal conductivity (374 W·m) compared to pure copper (at 400℃). -1 ·K -1 (with a tensile strength of 107 MPa), which significantly improves the high-temperature mechanical strength while maintaining the excellent thermal conductivity of copper.

[0101] Example 2

[0102] A method for preparing a three-dimensional five-directional braided tungsten fiber continuously distributed reinforced copper matrix composite material.

[0103] (1) Tungsten fiber with a diameter of 100 μm was treated as follows: First, it was washed with 50 g / L sodium hydroxide aqueous solution at 90°C for 15 min to remove oil. Then it was washed with deionized water until neutral and dried with hot air. Next, it was soaked in 10% dilute nitric acid solution at room temperature for 15 min to remove the oxide layer on the surface of the tungsten fiber. Then it was washed with alcohol and deionized water until neutral and dried with hot air. Finally, the surface of the tungsten fiber was roughened with a mixed solution of sodium hydroxide (5wt%) and sodium silicate (8g / L) for 20 min. After rinsing with deionized water several times, the pretreated fiber was obtained.

[0104] (2) The pretreated fiber and 100μm copper fiber are bundled together at a volume ratio of 1:10 to form a composite fiber bundle; then the composite fiber bundle is introduced into a three-dimensional loom and a five-way weaving process is adopted to construct a three-dimensional continuous grid structure with a surface weaving angle of 39.3°. Figure 3 The diagram shows a three-dimensional continuous grid structure, in which the bundled yarns are interwoven evenly and regularly, without obvious bending, twisting or loosening, and the yarns form a continuous three-dimensional reinforcing phase structure.

[0105] (3) Encapsulate the three-dimensional continuous mesh structure in a vacuum stainless steel sheath (vacuum degree ≤10). -1 The copper was placed in a hot isostatic pressing apparatus and kept at 850℃ and 150MPa for 3 hours to fully densify the copper, resulting in a three-dimensional five-directional braided tungsten fiber continuously distributed reinforced copper-based composite material with a copper volume fraction of 91% after densification. Figure 4The macroscopic image of the prepared composite material is shown, which shows that the copper matrix and the reinforcing phase skeleton are tightly bonded together, and no obvious pores or cracks are observed.

[0106] Through high-temperature tensile testing, the obtained three-dimensional four-way braided tungsten fiber continuously distributed reinforced copper matrix composite material exhibits an axial high-temperature elastic modulus of 124 GPa and a high-temperature tensile strength of 139 MPa at 500℃. Through high-temperature thermal conductivity testing at 500℃, the obtained three-dimensional five-way braided tungsten fiber continuously distributed reinforced copper matrix composite material exhibits an axial high-temperature thermal conductivity of 347 W·m. -1 ·K -1 The prepared composite material has a lower elastic modulus (98 GPa) and thermal conductivity (374 W·m) compared to pure copper (at 400℃). -1 ·K -1 (with a tensile strength of 107 MPa), which significantly improves the high-temperature mechanical strength while maintaining the excellent thermal conductivity of copper.

[0107] Example 3

[0108] A method for preparing 2.5D braided tantalum fiber continuously distributed reinforced copper matrix composites.

[0109] (1) Treating tantalum fibers with a diameter of 200 μm: First, use 50 g / L sodium hydroxide aqueous solution to wash and remove oil at 90°C for 15 min, then wash with deionized water until neutral and dry with hot air; then soak in 10% dilute nitric acid solution at room temperature for 15 min to remove the oxide layer on the surface of the tantalum fibers, and wash with alcohol and deionized water until neutral and dry with hot air; finally, roughen the surface of the tantalum fibers with 40% hydrofluoric acid solution for 15 min, and obtain the pretreated fibers after multiple rinsing with deionized water.

[0110] (2) Tantalum fibers are woven into a 2.5D skeleton using a three-dimensional loom. The porosity of the skeleton is 70%. Subsequently, the skeleton is heated in nitrogen at 400°C for 2 hours to complete the high-temperature treatment and obtain a fiber frame. Then, a 60×60×15mm copper block is laid on the surface of the fiber frame and heated in a vacuum melting furnace under a vacuum environment (≤10). -2 Pa) was heated from 25℃ to 1150℃ at a heating rate of 10℃ / min and held for 50min; after cooling, a three-dimensional continuous mesh structure was obtained. Figure 5 The diagram shows a three-dimensional continuous grid structure, in which the bundled yarns are interwoven evenly and regularly, without obvious bending, twisting or loosening, and the yarns form a continuous three-dimensional reinforcing phase structure.

[0111] (3) The three-dimensional continuous mesh structure was placed in a cold rolling mill and rolled in multiple passes at room temperature (25°C). The first pass had a reduction rate of 50%, and the subsequent passes had a reduction rate of 15%, with a total cumulative reduction rate of 70%. The interval between passes was 5 minutes. This process fully densifies the copper-based composite material, resulting in a 2.5D braided tantalum fiber continuously distributed reinforced copper-based composite material. Figure 6 The macroscopic image of the prepared composite material is shown, which shows that the copper matrix and the reinforcing phase skeleton are tightly bonded together, and no obvious pores or cracks are observed.

[0112] Example 4

[0113] A method for preparing copper-based composite materials reinforced with continuously distributed tungsten fibers in a mesh structure.

[0114] (1) Tungsten fiber with a diameter of 100 μm was treated as follows: First, it was washed with 50 g / L sodium hydroxide aqueous solution at 90°C for 15 min to remove oil. Then it was washed with deionized water until neutral and dried with hot air. Next, it was soaked in 10% dilute nitric acid solution at room temperature for 15 min to remove the oxide layer on the surface of the tungsten fiber. Then it was washed with alcohol and deionized water until neutral and dried with hot air. Finally, the surface of the tungsten fiber was roughened with a mixed solution of sodium hydroxide (5wt%) and sodium silicate (8g / L) for 20 min. After rinsing with deionized water several times, the pretreated fiber was obtained.

[0115] (2) The pretreated fiber was placed in an electroplating solution device as the cathode and pure copper as the anode. Copper sulfate (200 g / L) and sulfuric acid (60 g / L) were used as the electroplating solution. The current density was controlled at 1 A / dm². Electroplating was carried out at 30 °C for 8 min. Copper ions were driven to migrate directionally to the surface of the tungsten fiber by an external power source and the thickness was continuously increased. Finally, a copper coating layer with a thickness of 30 μm (copper-coated tungsten fiber coaxial composite fiber) was formed on the surface of the pretreated fiber. The fiber was then introduced into a three-dimensional loom and woven into a three-dimensional continuous mesh structure with a porosity of 78%. Figure 7 This shows one of the SEM images of copper-coated tungsten fiber coaxial composite fibers. Figure 8 The second SEM image of the copper-coated tungsten fiber coaxial composite fiber shows that the copper is uniformly, continuously, and completely covered on the surface of the tungsten fiber, and the coating thickness is relatively uniform, achieving the design expectation. Figure 9 The SEM image of the three-dimensional continuous grid structure shows that the bundled yarns are interwoven evenly and regularly, without obvious bending, twisting or loosening, and the yarns form a continuous three-dimensional reinforcing phase structure.

[0116] (3) The three-dimensional continuous mesh structure is placed in a cold rolling mill and rolled in multiple passes at room temperature (25°C). The first pass has a reduction rate of 10%, and the subsequent passes have a reduction rate of 5%, with a total cumulative reduction rate of 70%. Vacuum stress relief annealing is carried out between passes at 900°C to fully densify the copper-based composite material and obtain a woven tungsten fiber continuously distributed reinforced copper-based composite material. Figure 10 The SEM image of the prepared composite material shows that the copper matrix and the reinforcing phase skeleton are tightly bonded, and no obvious pores or cracks were observed.

[0117] As can be seen from the above embodiments, the composite material prepared by the method of the present invention uses reinforcing phase fibers woven into a spatial continuous mesh as a load-bearing skeleton; the copper matrix fills the pores of the continuous mesh skeleton and is tightly bonded to the reinforcing phase fibers, forming a spatially interpenetrating continuous network of copper and reinforcing phase. The volume fraction of copper is 91%; the axial elastic modulus of the composite material at 500℃ is 122-124 GPa, the tensile strength is 133-139 MPa, and the axial high-temperature thermal conductivity is 344-347 W·m. -1 ·K -1 It possesses excellent high-temperature mechanical properties and thermal conductivity.

[0118] The present invention has been described in detail above with reference to preferred embodiments and exemplary examples. However, it should be noted that these specific embodiments are merely illustrative explanations of the invention and do not constitute any limitation on the scope of protection of the invention. Various improvements, equivalent substitutions, or modifications can be made to the technical content and embodiments of the present invention without departing from the spirit and scope of protection of the invention, and all such modifications fall within the scope of protection of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A method for preparing a copper-based composite material with a continuously distributed phase space reinforcement, characterized in that, The method includes: Step 1: Clean and roughen the surface of the reinforcing phase fiber to obtain pretreated fiber; Step 2: Prepare a spatially continuous structure of copper and pretreated fibers to construct a three-dimensional continuous mesh structure; Step 3: The three-dimensional continuous mesh structure is densified to obtain the composite material.

2. The method according to claim 1, characterized in that, Preferably, in step 1, the reinforcing phase fiber is any one of metal fiber, metal oxide fiber, metal nitride fiber, and carbon fiber.

3. The method according to claim 1, characterized in that, In step 1, the diameter of the reinforcing phase fiber is 100-500 μm.

4. The method according to claim 1, characterized in that, In step 1, the cleaning includes alkaline washing and acid washing. The alkaline washing is used to remove oil from the surface of the reinforcing phase fiber, and the acid washing is used to remove the oxide layer from the surface of the reinforcing phase fiber.

5. The method according to claim 1, characterized in that, In step 2, the copper is introduced by means of interfacial composition control.

6. The method according to claim 5, characterized in that, The interface component regulation refers to introducing a copper coating layer on the surface of the pretreated fiber, and the copper coating layer and the pretreated fiber form a coaxial composite fiber.

7. The method according to claim 1, characterized in that, In step 2, the copper is introduced through a co-weaving process with pretreated fibers.

8. The method according to claim 1, characterized in that, In step 2, the copper is introduced through melt infiltration after the reinforcing phase fibers are woven into a skeleton.

9. The method according to claim 1, characterized in that, In step 3, the densification process is cold rolling or hot isostatic pressing.

10. A composite material prepared by the method according to any one of claims 1-9, characterized in that, The volume fraction of copper is 70%-95%.

Images