Preparation method of high-strength high-conductivity copper-silver-carbon composite material

Abstract

The application discloses a preparation method of high-strength high-conductivity copper-silver-carbon composite material. The surface oxide layers of copper powder and silver particles are removed first, the copper powder and the silver particles are put into a crucible of a vacuum melting furnace and are melted to obtain a copper-silver alloy melt, the temperature of the copper-silver alloy melt is reduced and the physical form of the copper-silver alloy melt is changed from liquid state to semi-solid state, carbon material is added and stirring is continued under the condition of turbulent stirring in vacuum, so that the carbon material is dispersed and suspended in the semi-solid copper-silver alloy melt, the copper-silver alloy melt is cast in a preheated casting mold, and the copper-silver-carbon composite material is obtained after demolding. The application not only solves the problem of uneven dispersion of carbon material caused by carbon floating, but also prepares the copper-silver-carbon composite material with lower cost and better relative comprehensive performance.

Description

Technical Field

[0001] This invention relates to the field of high-strength, high-conductivity copper-silver-carbon composite materials, and in particular to a method for producing such a composite material. Background Technology

[0002] The conductor material of the magnetic field winding coil must have both high strength and high conductivity. It is usually required that its strength is greater than 700MPa and its conductivity is greater than 75% IACS. At present, copper-silver alloy materials mainly meet these requirements. Compared with other alloys, copper-silver alloys have a better mechanical properties and conductivity matching relationship.

[0003] This is because both Cu and Ag have a face-centered cubic crystal structure. After appropriate deformation and heat treatment processes, such as tensile deformation and intermediate heat treatment, copper-silver alloys possess high strength while maintaining good electrical conductivity due to the absence of introduced additional scattering. Studies have shown that copper-silver alloys with a silver content of <8wt% exhibit increased tensile strength to 400-800 MPa and decreased electrical conductivity to 60%-90% IACS compared to pure copper after the addition of silver.

[0004] As the requirements for magnetic field strength continue to increase, both strength and conductivity need to be further improved to meet these requirements. However, copper-silver alloys are typical work-hardening alloys, and further improvement in mechanical properties often requires drastic plastic processing. During this process, dislocations accumulate, and the higher the processing rate, the greater the dislocation density, which in turn reduces electrical conductivity.

[0005] While increasing the silver content can improve mechanical properties, Ag is more expensive than Cu, making it crucial to improve overall performance without increasing the Ag content. Most researchers have tried to control the microstructure by adding elements such as Zr and Sc to Cu-Ag alloys. Although this can improve tensile strength, the severe defects formed inside the material lead to a significant decrease in electrical conductivity.

[0006] Currently, strengthening materials by adding second-phase particles into the matrix has the least impact on conductivity. Therefore, finding suitable additive phases to enable Cu-Ag alloys to achieve high strength while maintaining good conductivity has gradually become a research focus.

[0007] Due to their outstanding characteristics such as light weight, excellent physical properties, high strength, thermal stability, and high electrical conductivity, carbon materials are increasingly being used in composite materials, such as graphene and carbon nanotubes. Numerous experiments have demonstrated that graphene has a good enhancing effect on the mechanical properties of metallic materials.

[0008] However, the quality, distribution, and integrity of carbon materials in the matrix significantly affect the electrical conductivity of composite materials. One pressing issue is the uniform dispersion of carbon materials in a metal matrix. Chinese patents with publication numbers CN108677040, CN108425033, CN108570574, CN108611521, and CN108342609 disclose different methods for adding carbon materials to copper-based alloy composite materials. These methods involve alloying pure copper, pure silver ingots, pure copper powder, pure silver powder, and graphene powder using argon gas protection, stirring the liquid alloy melt using mechanical stirring, and simultaneously cooling, holding, casting, and post-processing the alloy melt to prepare the composite material.

[0009] However, in the aforementioned patented technologies, there is a problem of carbon material floating during the stirring of the liquid alloy melt. This prevents the carbon material from being fully distributed in the alloy melt. The aforementioned patented technologies do not disclose how to solve the problem of carbon material floating, which makes it impossible to directly prepare copper-silver-carbon composite materials with good dispersion in actual production processes. Summary of the Invention

[0010] To address the shortcomings of existing technologies, the purpose of this invention is to provide a semi-solid stirred casting method for preparing carbon-reinforced copper-silver alloys. This method overcomes the problem of uneven dispersion of carbon materials floating in molten metal, achieving a uniform distribution of carbon materials. The addition of carbon materials provides highly conductive channels, enhancing electron transport and improving conductivity, resulting in composite materials with excellent overall performance. This method is simple to prepare and suitable for large-scale industrial production.

[0011] To achieve the above objectives, the technical solution adopted by this invention is: a method for preparing a high-strength, high-conductivity copper-silver-carbon composite material, comprising the following steps:

[0012] Step 1, Pretreatment, to remove the surface oxide layer of copper powder and silver particles;

[0013] The pretreatment specifically includes oxide layer removal treatment, which involves placing copper powder and silver particles separately inside a tube furnace and heating them in a hydrogen and argon atmosphere to remove the oxide layer on the surface of the copper powder and silver particles.

[0014] Before removing the oxide layer, copper powder and silver particles were ultrasonically cleaned separately. The copper powder and silver particles were put into an ultrasonic cleaner for ultrasonic cleaning and then dried.

[0015] Then, copper powder and silver particles are placed in a tube furnace to remove the oxide layer. The temperature of the tube furnace is raised to 200-800℃, and a mixed atmosphere of hydrogen and argon is introduced and kept at that temperature for 1-3 hours to remove the oxide layer on the surface of the copper powder and silver particles. Then, the furnace is cooled to room temperature.

[0016] After copper powder is separately put into an ultrasonic cleaner, it is sequentially subjected to ultrasonic cleaning with alcohol, ultrasonic cleaning with distilled water, and drying, and the process is repeated multiple times.

[0017] After the silver particles are individually put into the ultrasonic cleaner, they are sequentially subjected to ultrasonic cleaning with alcohol, ultrasonic cleaning with distilled water, and drying, and the process is repeated multiple times.

[0018] Alcohol ultrasonic cleaning involves first adding alcohol to an ultrasonic cleaner, then activating the ultrasonic waves to perform ultrasonic cleaning.

[0019] Distilled water ultrasonic cleaning treatment involves first adding distilled water to the ultrasonic cleaner, and then starting the ultrasonic cleaner to perform ultrasonic cleaning, thus achieving ultrasonic cleaning of distilled water.

[0020] Step 2, smelting process: copper powder and silver particles are put into the crucible of a vacuum smelting furnace. The molar ratio of copper powder to silver particles is 400 to 100:1. Vacuum high-temperature smelting is carried out. During the smelting process, the vacuum degree (gas pressure) of the vacuum smelting furnace is kept below 5 MPa to obtain copper-silver alloy melt.

[0021] Step 3: Transformation and Maintenance of Physical State. The temperature of the copper-silver alloy melt is lowered and maintained by controlling the temperature of the vacuum melting furnace, keeping it within the corresponding semi-solid temperature range. The temperature of the copper-silver alloy melt is lowered to 1000–1080°C, transforming its physical state from liquid to semi-solid. After this transformation, the temperature is maintained at 1000–1080°C for heat preservation, ensuring the melt remains in a semi-solid state. Finally, a stirring paddle is used to turbulently agitate the semi-solid copper-silver alloy melt under vacuum.

[0022] Step 4: While performing turbulent stirring under vacuum, add carbon material and continue stirring. Add carbon material at a molar mass ratio of 0.1-0.5% mol. Carbon material includes, but is not limited to, graphene, carbon nanotubes, graphite and carbon quantum dots. Maintain the temperature of the copper-silver alloy melt at 1000-1080℃. During stirring, the physical state of the copper-silver alloy melt remains semi-solid, allowing the carbon material to be uniformly dispersed and suspended in the semi-solid copper-silver alloy melt. The semi-solid copper-silver alloy melt fixes and stabilizes the carbon material dispersed inside it.

[0023] Before stirring, the surface of the stirring paddle is coated with high-temperature adhesive and then inserted into the semi-solid copper-silver alloy melt. The copper-silver alloy melt is mechanically stirred by the stirring paddle at a speed of 800-1200 rpm.

[0024] Step 5: Preheat the casting mold to a temperature of 400-500℃, then pour the copper-silver alloy melt into the preheated casting mold. After demolding, a copper-silver-carbon composite material is obtained.

[0025] To address the shortcomings of existing technologies, this invention adds a small amount of carbon material to the alloy material, employs vacuum induction melting, and utilizes an innovative semi-solid stirring process. This ensures that the carbon material has high dispersion and a relatively intact structure within the matrix. The microstructure of the semi-solid alloy features solid particles suspended in a liquid matrix. The uniformly dispersed carbon material can effectively bear tensile stress, and the carbon material located at the grain boundaries of the copper-silver alloy acts as dislocation pinning, hindering dislocation movement and migration, thereby enhancing the mechanical properties of the composite material. Semi-solid forming effectively reduces porosity and shrinkage defects during the casting process, improving the density and mechanical properties of the casting. The carbon material achieves strong interfacial bonding with the matrix, and its high electron mobility enhances the overall charge transfer rate, thus improving conductivity.

[0026] The advantages of this invention compared to the prior art are: this invention not only solves the problem of uneven dispersion of carbon materials caused by carbon floating, but also produces copper-silver-carbon composite materials with lower cost and better overall performance. Attached Figure Description

[0027] Figure 1 This is a metallographic image of the grains in Example 1.

[0028] Figure 2 This is a physical image of Example 1.

[0029] Figure 3 for Figure 2 The left view of the actual object. Detailed Implementation

[0030] Example 1

[0031] A method for preparing a high-strength, high-conductivity copper-silver-carbon composite material. Figures 1 to 3 As shown, the carbon material added in this embodiment is graphene powder, and the process includes the following steps:

[0032] Step 1: Weigh high-purity copper and silver and place them in an ultrasonic cleaner. Wash them three times with circulating alcohol and distilled water for 10 minutes each time to remove surface contaminants and grease. After drying, weigh 16 mol of high-purity copper and 0.18 mol of silver, with a copper-silver molar ratio of 800:9. Place them separately in a tube furnace and heat at 350℃ for 1 hour in H2 (50 sccm / min) and Ar (500 sccm / min) atmospheres to remove the surface oxide layer. Then cool to room temperature with the furnace.

[0033] Step 2: Place the copper and silver blocks inside the vacuum induction furnace. Once the vacuum level reaches below 5 MPa, turn on the melting equipment to melt the metal. Set the temperature to 1100℃ and the melting time to 2 hours.

[0034] Step 3: When the alloy melt temperature drops to a semi-solid temperature of 1000-1080℃, add graphene powder (0.1 mol). Then insert a standard single stirring paddle. The stirring paddle needs to be preheated to 400-500℃ for at least 30 minutes before insertion. The stirring paddle must be coated with high-temperature adhesive before use to prevent contamination of the molten pool environment; the mechanical stirring speed is 1000 rpm, and stirring is performed for 5-15 minutes.

[0035] Step 4: After all the micron-sized graphene particles are dispersed in the melt, pour the mixture into an iron mold preheated to 400–500°C for 1–2 hours, and allow it to cool at room temperature to obtain Sample 1, the copper-silver graphene composite material. Figures 1 to 3 As shown in Table 1, the conductivity (%IACS), elongation (%), and tensile strength (MPa) of sample 1 were tested respectively.

[0036] Example 2

[0037] A method for preparing a high-strength, high-conductivity copper-silver-carbon composite material, wherein the carbon material added in this embodiment is carbon nanotube powder, includes the following steps:

[0038] Step 1: Weigh high-purity copper and silver and place them in an ultrasonic cleaner. Wash them three times with circulating alcohol and distilled water for 10 minutes each time to remove surface contaminants and grease. After drying, weigh 16 mol of high-purity copper and 0.18 mol of silver, with a copper-silver ratio of 800:9. Place them separately in a tube furnace and heat at 350°C for 1 hour in H2 (50 sccm / min) and Ar (500 sccm / min) atmospheres to remove the surface oxide layer. Then cool to room temperature with the furnace.

[0039] Step 2: Place the copper and silver blocks inside the vacuum induction furnace. Once the vacuum level reaches below 5 MPa, turn on the melting equipment to melt the metal. Set the temperature to 1100℃ and the melting time to 2 hours.

[0040] Step 3: When the alloy melt temperature drops to a semi-solid temperature of 1000-1080℃, add carbon nanotube powder (0.1 mol). Then insert a standard single stirring paddle. The stirring paddle needs to be preheated to 400-500℃ for at least 30 minutes before insertion. The stirring paddle must be coated with high-temperature adhesive before use to prevent contamination of the molten pool environment; the mechanical stirring speed is 1000 rpm, and stirring is performed for 5-15 minutes.

[0041] Step 4: After all the micron-sized carbon nanotube particles are dispersed in the melt, they are cast into an iron mold preheated at 400-500℃ for 1-2 hours and cooled at room temperature to obtain sample 2, copper-silver carbon nanotube composite material. The conductivity (%IACS), elongation (%) and tensile strength (MPa) of sample 2 are tested and shown in Table 1.

[0042] Example 3

[0043] A method for preparing a high-strength, high-conductivity copper-silver-carbon composite material, wherein the carbon material added in this embodiment is carbon-carbon quantum dots, includes the following steps:

[0044] Step 1: Weigh high-purity copper and silver and place them in an ultrasonic cleaner. Wash them three times with circulating alcohol and distilled water for 10 minutes each time to remove surface contaminants and grease. After drying, weigh 16 mol of high-purity copper and 0.18 mol of silver, with a copper-silver ratio of 800:9. Place them separately in a tube furnace and heat at 350°C for 1 hour in H2 (50 sccm / min) and Ar (500 sccm / min) atmospheres to remove the surface oxide layer. Then cool to room temperature with the furnace.

[0045] Step 2: Place the copper and silver blocks inside the vacuum induction furnace. Once the vacuum level reaches below 5 MPa, turn on the melting equipment to melt the metal. Set the temperature to 1100℃ and the melting time to 2 hours.

[0046] Step 3: When the alloy melt temperature drops to a semi-solid temperature of 1000–1080°C, add 0.1 mol of carbon quantum dots. Then insert a standard single-stirring paddle. The paddle must be preheated to 400–500°C for at least 30 minutes before insertion. Before use, the paddle must be coated with high-temperature adhesive to prevent contamination of the molten pool environment. The mechanical stirring speed is 1000 rpm, and stirring time is 5–15 minutes.

[0047] Step 4: After all the carbon quantum dot particles are dispersed in the melt, the mixture is cast into an iron mold preheated at 400-500℃ for 1-2 hours and cooled at room temperature to obtain sample 3, a copper-silver-carbon quantum dot composite material. The conductivity (%IACS), elongation (%), and tensile strength (MPa) of sample 3 are tested and shown in Table 1.

[0048] Example 4

[0049] A method for preparing pure copper material includes the following steps:

[0050] Step 1: Weigh high-purity copper into an ultrasonic cleaner and wash it three times with circulating alcohol and distilled water for 10 minutes each time to remove surface contaminants and grease. After drying, weigh 16 mol of high-purity copper and place it in a tube furnace at 350°C for 1 hour in an atmosphere of H2 (50 sccm / min) and Ar (500 sccm / min) to remove the surface oxide layer. Then, cool the furnace to room temperature.

[0051] Step 2: Place the copper block inside the vacuum induction furnace. Once the vacuum level reaches below 5 MPa, turn on the melting equipment to melt the copper. Set the temperature to 1100℃ and the melting time to 2 hours.

[0052] Step 3: Insert a standard single stirring paddle. The stirring paddle needs to be preheated to 400-500℃ for at least 30 minutes before insertion. Before use, the stirring paddle must be coated with high-temperature adhesive to prevent contamination of the molten pool environment; the mechanical stirring speed is 1000 rpm, and stirring is performed for 5-15 minutes.

[0053] Step 4: The sample was cast into an iron mold preheated at 400-500℃ for 1-2 hours and cooled at room temperature to obtain sample 4 copper ingot. The conductivity (%IACS), elongation (%) and tensile strength (MPa) of sample 4 were tested and are shown in Table 1.

[0054] Example 5

[0055] A method for preparing a copper-silver composite material includes the following steps:

[0056] Step 1: Weigh high-purity copper and silver and place them in an ultrasonic cleaner. Wash them three times with circulating alcohol and distilled water for 10 minutes each time to remove surface contaminants and grease. After drying, weigh 16 mol of high-purity copper and 0.18 mol of silver, with a copper-silver ratio of 800:9. Place them separately in a tube furnace and heat at 350°C for 1 hour in H2 (50 sccm / min) and Ar (500 sccm / min) atmospheres to remove the surface oxide layer. Then cool to room temperature with the furnace.

[0057] Step 2: Place the copper and silver blocks inside the vacuum induction furnace. Once the vacuum level reaches below 5 MPa, turn on the melting equipment to melt the metal. Set the temperature to 1100℃ and the melting time to 2 hours.

[0058] Step 3: When the alloy melt temperature drops to a semi-solid temperature of 1000-1080℃, insert a standard single stirring paddle. The stirring paddle needs to be preheated to 400-500℃ for at least 30 minutes before insertion. The stirring paddle must be coated with high-temperature adhesive before use to prevent contamination of the molten pool environment; the mechanical stirring speed is 1000 rpm, and stirring is performed for 5-15 minutes.

[0059] Step 4: Cast the copper-silver composite material into an iron mold preheated at 400-500℃ for 1-2 hours, and then cool it at room temperature.

[0060] Comparative Example 1

[0061] The Chinese patent with publication number CN108677040 has a silver content of 24%.

[0062] A method for preparing a copper-based alloy billet with good electrical conductivity includes the following steps:

[0063] (1) Using pure copper ingots, pure silver ingots, pure silver powder and graphene powder as raw materials, the composition is 87wt% pure copper ingots, 10wt% pure silver ingots, 2wt% pure silver powder and 1wt% graphene powder, with a total of 100%. The diameter of the pure silver powder is 0.05-100μm, and its surface oxide is removed after reduction treatment.

[0064] (2) First, mix pure copper ingots and pure silver ingots and heat them to 1100℃ to melt them into an alloy melt. After holding the temperature for 10 minutes, use argon gas to protect the surface of the melt and add pure silver powder and graphene powder. Use mechanical stirring to fully stir the alloy melt for 1-5 minutes. At the same time, lower the temperature of the alloy melt to 1000℃ and hold it for 10-15 minutes to make the alloy melt solidify rapidly and form a semi-solid mixed structure melt.

[0065] (3) The semi-solid mixed structure melt is poured into a mold cooled by circulating water to form an ingot, and cooled to room temperature at a rate of 80℃ / min to obtain a copper-based alloy billet.

[0066] Comparative Example 2

[0067] The Chinese patent with publication number CN108425033 has a silver content of 24%.

[0068] A method for preparing a high-yield-strength copper-based alloy billet includes: mixing 75 wt% pure copper ingots and 14 wt% pure silver ingots, heating the mixture to 1050-1700℃ to melt it into an alloy melt, holding it at this temperature for 10 min, protecting the melt surface with argon gas, and adding 10 wt% pure silver powder and 1 wt% graphene powder. The alloy melt is then mechanically stirred for 1-5 min, while simultaneously lowering the temperature to 900-1600℃ and holding it for 10-15 min to allow the alloy melt to solidify rapidly and form a semi-solid mixed structure. The semi-solid mixed structure melt is then poured into a mold cooled by circulating water to form an ingot, and cooled to room temperature at a rate of 50-200℃ / min to obtain the copper-based alloy billet. The copper-based alloy billet is then heated to 7... The forging process involves forging the ingot at 00-720℃ for 1 hour, then distributing the forging along three orthogonal directions (longitudinal, transverse, and axial) with a forging reduction of 20-40% in each direction. The forged ingot is then air-cooled to room temperature, then heated to 500℃ and held for 1 hour. This process is repeated three times, with the forging reduction in each direction being 10-30%. The forged ingot is then air-cooled to room temperature, then heated to 400℃ and held for 1 hour. This process is repeated three times, with the forging reduction in each direction being 10-30%. Finally, the forged ingot is air-cooled to room temperature, then heated to 300℃ and held for 1 hour. This process is repeated three times, with the forging reduction in each direction being 10-30%.

[0069] Comparative Example 3

[0070] The Chinese patent with publication number CN108570574 states that the silver content is 30%.

[0071] A method for preparing a graphene-containing copper-based alloy billet includes the following steps:

[0072] (1) Using pure copper ingots, pure silver ingots, pure copper powder and graphene powder as raw materials, the composition is 65wt% pure copper ingots, 30wt% pure silver ingots, 4wt% pure copper powder and 1wt% graphene powder, wherein the diameter of the pure copper powder is 50-100μm, and its surface oxide is removed after reduction treatment.

[0073] (2) First, mix pure copper ingots and pure silver ingots and heat them to 1050°C to melt them into an alloy melt. After holding the temperature for 10 minutes, add pure copper powder and graphene powder. Stir the alloy melt thoroughly for 1-5 minutes using mechanical stirring. At the same time, lower the temperature of the alloy melt to 900°C and hold it for 10-15 minutes to allow the alloy melt to solidify rapidly and form a semi-solid mixed structure melt.

[0074] (3) The semi-solid mixed structure melt is poured into a mold cooled by circulating water to form an ingot, and cooled to room temperature at a rate of 50-200℃ / min to obtain a high-strength, high-conductivity copper-based alloy billet containing graphene.

[0075] Comparative Example 4

[0076] The Chinese patent with publication number CN108611521 states that the silver content is 12%.

[0077] A method for preparing copper-based alloy billets includes the following steps:

[0078] (1) Using pure copper ingots, pure silver ingots, pure copper powder and graphene powder as raw materials, its composition is 85wt% pure copper ingots, 12wt% pure silver ingots, 2wt% pure copper powder and 1wt% graphene powder.

[0079] (2) First, mix pure copper ingots and pure silver ingots and heat them to 1100°C to melt them into an alloy melt. After holding the temperature for 10 minutes, use argon gas to protect the surface of the melt and add pure copper powder and graphene powder. Stir the alloy melt thoroughly for 3 minutes. At the same time, lower the temperature of the alloy melt to 900°C and hold it for 10 minutes to allow the alloy melt to solidify rapidly and form a semi-solid mixed structure melt.

[0080] (3) The semi-solid mixed structure melt is poured into a mold cooled by circulating water to form an ingot, and cooled to room temperature at a rate of 80℃ / min to obtain a copper-based alloy billet.

[0081] The conductivity, elongation, and tensile strength of samples 1 to 4 of each embodiment of the present invention were tested and are shown in Table 1. By comparison, it can be seen that the molar ratio of silver in the present invention is 0.18% and the molar ratio of carbon material is 0.1%. However, the conductivity of samples 1 to 4 is greater than the maximum value of 90% IACS recorded in comparative examples 1 to 4, and they have better elongation. This is because the present invention solves the problem of uneven dispersion of carbon material caused by carbon floating. Furthermore, since the present invention significantly reduces the input ratio of relatively expensive silver, it can also reduce production costs, thereby obtaining a copper-silver-graphite composite material with lower production costs and better overall performance.

[0082]

[0083] Table 1 - Comparison of Experimental Data

Claims

1. A method for preparing a high-strength, high-conductivity copper-silver-carbon composite material, characterized in that: Includes the following steps, Step 1, Pretreatment, to remove the surface oxide layer of copper powder and silver particles; Step 2, smelting process: copper powder and silver particles are put into the crucible of a vacuum smelting furnace, wherein the molar ratio of silver is less than 5%, and vacuum high-temperature smelting is carried out to obtain copper-silver alloy melt. Step 3: Transform and maintain the physical state. Lower the temperature of the copper-silver alloy melt to change the physical state of the copper-silver alloy melt from liquid to semi-solid. Perform heat preservation treatment to maintain the physical state of the copper-silver alloy melt as semi-solid. Then use a stirring paddle to turbulently stir the semi-solid copper-silver alloy melt under vacuum. Step 4: While turbulent stirring under vacuum, add carbon material and continue stirring. The mass molar ratio of carbon material is less than 1%, so that the carbon material can be uniformly dispersed and suspended in the semi-solid copper-silver alloy melt. The semi-solid copper-silver alloy melt fixes and stabilizes the carbon material dispersed inside it. Step 5: Cast the copper-silver alloy melt into a preheated casting mold, and obtain the copper-silver-carbon composite material after demolding.

2. The method for preparing a high-strength, high-conductivity copper-silver-carbon composite material according to claim 1, characterized in that: In step 3, the temperature of the copper-silver alloy melt is reduced and maintained by controlling the temperature of the vacuum melting furnace. In steps 3 and 4, the temperature of the copper-silver alloy melt is maintained within the semi-solid temperature range corresponding to the copper-silver alloy melt.

3. The method for preparing a high-strength, high-conductivity copper-silver-carbon composite material according to claim 1, characterized in that: In step 2, the molar mass ratio of copper powder to silver particles is 400–100:

1. In step 4, the carbon material is added at a molar mass ratio of 0.1 to 0.5 mol.

4. The method for preparing a high-strength, high-conductivity copper-silver-carbon composite material according to claim 1, characterized in that: The carbon materials include, but are not limited to, graphene, carbon nanotubes, graphite, and carbon quantum dots.

5. The method for preparing a high-strength, high-conductivity copper-silver-carbon composite material according to claim 3, characterized in that: In step 3, the temperature of the copper-silver alloy melt is reduced to 1000–1080°C, and after the copper-silver alloy melt transforms into a semi-solid state, the temperature of the copper-silver alloy melt is maintained at 1000–1080°C. In step 4, the temperature of the copper-silver alloy melt is maintained at 1000-1080℃, and the physical state of the copper-silver alloy melt remains semi-solid during the stirring process.

6. The method for preparing a high-strength, high-conductivity copper-silver-carbon composite material according to claim 1, characterized in that: In step 4, the surface of the stirring paddle is first coated with high-temperature adhesive, and then the stirring paddle is inserted into the semi-solid copper-silver alloy melt. The copper-silver alloy melt is mechanically stirred by the stirring paddle, and the stirring paddle speed is 800-1200 rpm.

7. The method for preparing a high-strength, high-conductivity copper-silver-carbon composite material according to claim 1, characterized in that: In step 2, the vacuum degree of the vacuum melting furnace is maintained below 5 MPa during the melting process. In step 4, the casting mold is preheated at a temperature of 400-500°C.

8. A method for preparing a high-strength, high-conductivity copper-silver-carbon composite material according to any one of claims 1 to 7, characterized in that: Step 1, the pretreatment includes oxide layer removal treatment, which involves placing the copper powder and the silver particles separately inside a tube furnace and heating them in a hydrogen and argon atmosphere to remove the oxide layer on the surface of the copper powder and silver particles.

9. The method for preparing a high-strength, high-conductivity copper-silver-carbon composite material according to claim 8, characterized in that: In step 1, before removing the oxide layer, the copper powder and the silver particles are ultrasonically cleaned. The copper powder and the silver particles are put into an ultrasonic cleaner for ultrasonic cleaning and then dried. Then, copper powder and silver particles are placed in a tube furnace to remove the oxide layer. The temperature of the tube furnace is raised to 200-800℃, and a mixed atmosphere of hydrogen and argon is introduced and kept at that temperature for 1-3 hours to remove the oxide layer on the surface of the copper powder and silver particles. Then, the furnace is cooled to room temperature.

10. The method for preparing a high-strength, high-conductivity copper-silver-carbon composite material according to claim 9, characterized in that: Step 1, After the copper powder is individually fed into the ultrasonic cleaner, it is sequentially subjected to alcohol ultrasonic washing, distilled water ultrasonic washing, and drying treatment, and the process is repeated multiple times. After the silver particles are individually fed into the ultrasonic cleaner, they are sequentially subjected to ultrasonic washing with alcohol, ultrasonic washing with distilled water, and drying, and the process is repeated multiple times. Alcohol ultrasonic cleaning involves first adding alcohol to an ultrasonic cleaner, then activating the ultrasonic waves to perform ultrasonic cleaning. Distilled water ultrasonic cleaning treatment involves first adding distilled water to the ultrasonic cleaner, and then starting the ultrasonic cleaner to perform ultrasonic cleaning, thus achieving ultrasonic cleaning of distilled water.

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