Preparation method of graphene reinforced tungsten-copper composite material

Abstract

The invention relates to the technical field of electrical material preparation, in particular to a preparation method of a graphene reinforced tungsten-copper composite material. Comprising the following steps that 40-50 parts by volume of graphene powder and 50-60 parts by volume of copper powder are weighed, stirred and mixed, and premixed graphene copper composite powder is obtained; 25-35 parts by volume of the premixed graphene copper composite powder and 2-4 parts by volume of absolute ethyl alcohol are weighed, mixed and ball-milled, then isostatic pressing forming, vacuum sintering, machining and powdering are conducted, and graphene copper composite powder is obtained; 60-80 parts by mass of tungsten powder, 32-36 parts by mass of copper powder, 4-8 parts by mass of graphene copper composite powder and 5-8 parts by mass of paraffin are weighed, mixed ball milling, cold press molding, vacuum sintering, re-pressing and re-sintering and cooling are conducted, and the graphene reinforced tungsten copper composite material is obtained. According to the preparation method disclosed by the invention, the graphene tungsten copper composite material with excellent mechanical property and electrical property is obtained by combining the graphene copper composite powder with a re-pressing and re-sintering process.

Description

Technical Field

[0001] This invention relates to the field of electrical materials preparation technology, specifically to a method for preparing graphene-reinforced tungsten-copper composite materials. Background Technology

[0002] Tungsten-copper alloys possess properties such as high temperature resistance, arc erosion resistance, weld resistance, low cutoff current, and low thermionic emission. They are widely used in electrical contact materials and high-temperature components in aerospace, especially as electrode materials, heat sinks, and electrical contacts. These alloys require not only good strength but also certain electrical and thermal conductivity. However, tungsten-copper alloys often suffer from poor bonding, low density, and insufficient mechanical properties. To address this, a third phase component, such as rare earth metals and their oxides, alumina-silicon carbide ceramic phases, or other metals, is added to improve the bonding between W and Cu, thereby increasing the density and mechanical properties of the WCu alloy. However, this often leads to a significant decrease in electrical properties. Graphene, hailed as a star material of the 21st century, possesses excellent electrical and thermal conductivity due to its unique two-dimensional planar structure. Its thermal conductivity is more than 10 times that of copper at room temperature, and it boasts the highest strength and hardness among known materials. As a third phase component in tungsten-copper alloys, graphene can synergistically enhance mechanical and electrical properties, improve density and uniformity, and increase the alloy's strength and toughness.

[0003] Patent CN106498209B describes the preparation of a graphene-doped tungsten-copper composite material by mixing nickel-plated graphene with tungsten powder and copper powder, cold pressing, and then melt infiltration and sintering. Patent CN120536772A describes the preparation of a tungsten-copper electrical contact material containing 1-4% graphene and other elements by adding a copper-containing solution to a polydopamine graphene suspension. Patent CN120099350A describes the preparation of a graphene-reinforced copper-based electrical contact material with high copper content and low tungsten content by copper-based treatment of the graphene surface. Although these patents have prepared graphene-tungsten-copper composite materials with synergistically improved mechanical properties and electrical conductivity, they still suffer from problems such as high graphene content, uneven distribution, and localized reactions between graphene and tungsten to form tungsten carbide. In particular, they still cannot meet the stringent requirements of high strength, high conductivity, and high corrosion resistance of tungsten-copper alloys under ultra-high voltage conditions. Therefore, the present invention provides a method for preparing graphene-reinforced tungsten-copper composite material. By pre-preparing graphene-copper composite powder, and then using a repressing and re-firing process, a short-process tungsten-copper composite material with uniform distribution of the reinforcing phase graphene in the tungsten-copper alloy and synergistic improvement in mechanical and electrical properties is obtained. Summary of the Invention

[0004] To address the aforementioned issues, this application provides a method for preparing graphene-reinforced tungsten-copper composite materials. This method utilizes graphene-copper composite powder combined with a repressing and re-firing process to obtain graphene-tungsten-copper composite materials with excellent mechanical and electrical properties.

[0005] To achieve the above objectives, this application provides a method for preparing graphene-reinforced tungsten-copper composite materials, comprising the following steps: S1. Weigh 40-50 parts of graphene powder and 50-60 parts of copper powder by volume and stir to mix to obtain premixed graphene-copper composite powder. S2. Weigh 25-35 parts of premixed graphene copper composite powder and 2-4 parts of anhydrous ethanol by volume, mix and ball mill, then isostatically press, vacuum sinter, machine and powder to obtain graphene copper composite powder. In the above process, during the powder preparation step, the ends of the high-speed rotating graphene-copper alloy rods partially melt under the plasma arc heating effect. Simultaneously, droplets rapidly cooled in an inert gas are ejected under centrifugal force and solidify into tiny spherical graphene-copper composite powder particles due to surface tension. Because graphene and copper have no solubility, only localized zone melting can be used; otherwise, they are prone to agglomeration, making it difficult to form uniformly distributed graphene-copper composite powder.

[0006] S3. Weigh 60-80 parts of tungsten powder, 32-36 parts of copper powder, 4-8 parts of graphene copper composite powder, and 5-8 parts of paraffin wax by mass, mix and ball mill, cold press, vacuum sinter, repress and refire, and cool to obtain a graphene-reinforced tungsten copper composite material.

[0007] In the above process, vacuum sintering removes volatiles such as paraffin wax at high temperatures and promotes shrinkage and densification of the sintered green body. The repressing and refiring process uses pure corundum to fill and compact the green body, which can prevent the copper phase from overflowing and flowing, and also helps to promote its shrinkage and densification.

[0008] Furthermore, the graphene powder and copper powder have the following characteristics: the copper powder has a particle size of 30-50 μm, the graphene powder has a sheet thickness of ≤3 nm, and the sheet size is ≤100 μm.

[0009] Furthermore, the ball milling described in step S2 is performed under the following conditions: air pressure of 1-5 MPa, nitrogen protection, grinding balls of copper with a diameter of 3-8 mm, grinding speed of 500-600 rpm, grinding time of 3-5 h, and the sum of the volume of the material and the grinding balls being 50%-60% of the volume of the ball mill cylinder.

[0010] Furthermore, the isostatic pressing is carried out at a pressurization rate of 8-10 MPa / min, pressurizing to 350-450 MPa, holding pressure for 3-5 min, and the blank size is ≥30 mm in diameter and ≥200 mm in length.

[0011] Furthermore, in step S2, the vacuum sintering is performed with a vacuum degree of 1-1.5 × 10⁻⁶. -3 Pa, heat to 960-1000℃ at a heating rate of 8-10℃ / min, and hold for 1.5-2 hours.

[0012] Furthermore, the machining process involves producing a graphene copper alloy rod with a diameter ≥30mm, one end having an external thread of 10-15mm in length, and thread parameters of M16×1.5mm.

[0013] Furthermore, the powder preparation employs a plasma rotating electrode atomization method with a vacuum degree <10. -2 Pa, filled with 99% pure argon gas to a pressure of 1 atm, motor operating speed of 10000-15000 rpm, plasma gun operating current of 800-1600 A, and push speed of 1.3-2.2 mm / s.

[0014] Furthermore, the ball milling described in step S3 is performed under the following conditions: air pressure of 1-5 MPa, nitrogen protection, grinding balls of tungsten copper with a diameter of 3-8 mm, grinding speed of 500-600 rpm, grinding time of 2-4 h, and material and grinding ball loading coefficient of 1 / 3-1 / 2.

[0015] Furthermore, the cold pressing process is carried out at a temperature of 25-28°C, with a pressurization rate of 8-10 MPa / min, to a pressure of 800-1000 MPa, and then held at that pressure for 2-3 minutes.

[0016] Furthermore, step S3 involves vacuum sintering at a vacuum level of 3-5 × 10⁻⁵. -3 Pa, heated to 1000-1030℃ at a heating rate of 6-8℃ / min, held for 1.5-2h, shrinkage rate is 1-3%.

[0017] Furthermore, the repressing and refiring process is carried out in a steel mold at room temperature with a reduction rate of 2-4%. After demolding, the repressed blank is placed in a corundum crucible and filled and compacted with pure corundum with a particle size of 200-250 mesh. The temperature is raised to 1280-1350℃ at a heating rate of 10-20℃ / min and held for 1.5-2 hours. During this period, hydrogen or decomposed ammonia is introduced at a flow rate of 20-30L / h.

[0018] In summary, this application has the following beneficial effects: The graphene-reinforced tungsten-copper composite material prepared in this application not only has a dense structure and uniform distribution of graphene and copper, but also avoids the conditions for the formation of tungsten carbide between tungsten and graphene. Copper is wrapped around the graphene, preventing the contact between graphene and tungsten. At the same time, the near-spherical powder formed by the atomization of the rotating electrode promotes the bonding between graphene and copper, improves the sintering strength of the subsequent material, and improves the fluidity, making the material mix uniformly, ensuring the homogeneity between the various phases, preventing segregation and sintering defects. It can give full play to the high strength and high conductivity of graphene, so that the strength and toughness of the composite material are synergistically improved, and it also has strong resistance to arc ablation. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A schematic diagram illustrating the principle of powder production via plasma rotating electrode atomization. Figure 2 Microscopic images of graphene sheets with a small number of layers; Figure 3 Image of graphene-copper composite powder prepared for atomization by rotating electrode; Figure 4 The following are SEM images of the tungsten-copper composite material after ablation: (a) is the overall view of the composite material; (b) is the surface morphology of region A in (a) after ablation; (c) is the surface morphology of region B in (a) after ablation; (d) is the EDS spectrum of point A in (b); and (e) is the EDS spectrum of point B in (c). Figure 5 SEM image of the fracture surface of tungsten-copper composite material; Figure 6 The images show the microstructure of graphene-tungsten-copper composite materials. (a) and (b) are W60Cu40; (c) and (d) are W70Cu30; (e) and (f) are W80Cu20. Figure 7 The microstructure diagram is shown in Comparative Example 5; Figure 8 This is a microscopic tissue diagram of Comparative Example 6. Detailed Implementation

[0021] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this invention.

[0022] In the specific embodiments of this application, the purity of graphene is 99%, the purity of copper powder is 99%, the purity of tungsten powder is 99%, and the average particle size of paraffin is 40 μm.

[0023] Example 1 A method for preparing a graphene-reinforced tungsten-copper composite material includes the following steps: S1. Weigh 40 parts graphene powder and 60 parts copper powder by volume and stir and mix (120 rpm, 1-2 h) to obtain premixed graphene-copper composite powder. S2. Weigh 30 parts by volume of premixed graphene copper composite powder and 3 parts by volume, mix and ball mill (gas pressure 3MPa, nitrogen protection, grinding balls are 5mm diameter copper balls, grinding speed 500rpm, grinding time 4h, the sum of the volume of the material and the grinding balls is 55% of the volume of the ball mill cylinder), then isostatically press (pressurize at a rate of 9MPa / min, pressurize to 400MPa, hold pressure for 4min, compact size is 30mm diameter and 200mm length), and vacuum sinter (vacuum degree 1×10⁻⁶). -3 The process involved heating the material to 1000℃ at a rate of 9℃ / min and holding it at that temperature for 1.5 hours; machining it into a graphene copper alloy rod with a diameter of 30mm, a 13mm long external thread at one end, and thread parameters of M16×1.5mm; and preparing the powder using a plasma rotating electrode atomization method (vacuum degree 0.5×10). -2 (The process involves filling the air with 99% pure argon gas to a pressure of 1 atm, setting the motor speed to 13000 rpm, the plasma gun operating current to 1200 A, and the pushing speed to 1.8 mm / s) to obtain graphene-copper composite powder. S3. Weigh out 60 parts by weight of tungsten powder, 32 parts by weight of copper powder, 8 parts by weight of graphene copper composite powder, and 5 parts by weight of paraffin wax. Mix and ball mill (air pressure 3MPa, nitrogen protection, grinding balls are tungsten copper balls with a diameter of 5mm, grinding speed 550rpm, grinding time 3h, material and grinding ball filling coefficient is 1 / 3), cold press forming (temperature 25℃, pressurization rate 9MPa / min, pressurization to 900MPa, holding pressure for 2min), vacuum sintering (vacuum degree 4×10 -3 The process involved heating the material to 1020℃ at a heating rate of 6℃ / min and holding it for 1.5h, followed by re-pressing and re-firing (re-pressing was carried out in a steel mold at room temperature with a reduction rate of 3%, and after demolding, the re-pressed blank was placed in an alumina crucible, filled and compacted with pure alumina with a particle size of 250 mesh, heated to 1310℃ at a heating rate of 15℃ / min and held for 1.5h, during which hydrogen or decomposed ammonia was passed through at a flow rate of 25L / h), and then cooled to 25℃ to obtain a graphene-reinforced tungsten-copper composite material (W60Cu40).

[0024] Example 2 A method for preparing a graphene-reinforced tungsten-copper composite material includes the following steps: S1. Weigh 40 parts graphene powder and 60 parts copper powder by volume and stir and mix (120 rpm, 1-2 h) to obtain premixed graphene-copper composite powder. S2. Weigh 30 parts by volume of premixed graphene copper composite powder and 3 parts by volume, mix and ball mill (gas pressure 3MPa, nitrogen protection, grinding balls are 5mm diameter copper balls, grinding speed 500rpm, grinding time 4h, the sum of the volume of the material and the grinding balls is 55% of the volume of the ball mill cylinder), then isostatically press (pressurize at a rate of 9MPa / min, pressurize to 400MPa, hold pressure for 4min, compact size is 30mm diameter and 200mm length), and vacuum sinter (vacuum degree 1×10⁻⁶). -3 The process involved heating the material to 1000℃ at a rate of 9℃ / min and holding it at that temperature for 1.5 hours; machining it into a graphene copper alloy rod with a diameter of 30mm, a 13mm long external thread at one end, and thread parameters of M16×1.5mm; and preparing the powder using a plasma rotating electrode atomization method (vacuum degree 0.5×10). -2 (The process involves filling the air with 99% pure argon gas to a pressure of 1 atm, setting the motor speed to 13000 rpm, the plasma gun operating current to 1200 A, and the pushing speed to 1.8 mm / s) to obtain graphene-copper composite powder. S3. Weigh out 70 parts tungsten powder, 24 parts copper powder, 6 parts graphene copper composite powder, and 6 parts paraffin wax by mass and mix them in a ball mill (air pressure 3MPa, nitrogen protection, grinding balls are 5mm diameter tungsten copper balls, grinding speed 550rpm, grinding time 3h, material and grinding ball filling coefficient 1 / 3), cold press forming (temperature 25℃, pressurization rate 9MPa / min, pressurization to 900MPa, holding pressure for 2min), vacuum sintering (vacuum degree 4×10 -3 The process involved heating the material to 1020℃ at a rate of 6℃ / min and holding it for 1.5h, followed by re-pressing and re-firing (re-pressing was carried out in a steel mold at room temperature with a reduction rate of 3%, and after demolding, the re-pressed blank was placed in an alumina crucible, filled and compacted with pure alumina of 250 mesh, heated to 1310℃ at a rate of 15℃ / min and held for 1.5h, during which hydrogen or decomposed ammonia was passed through at a flow rate of 25L / h), and then cooled to 25℃ to obtain a graphene-reinforced tungsten-copper composite material (W70Cu30).

[0025] Example 3 A method for preparing a graphene-reinforced tungsten-copper composite material includes the following steps: S1. Weigh 40 parts graphene powder and 60 parts copper powder by volume and stir and mix (120 rpm, 1-2 h) to obtain premixed graphene-copper composite powder. S2. Weigh 30 parts by volume of premixed graphene copper composite powder and 3 parts by volume, mix and ball mill (gas pressure 3MPa, nitrogen protection, grinding balls are 5mm diameter copper balls, grinding speed 500rpm, grinding time 4h, the sum of the volume of the material and the grinding balls is 55% of the volume of the ball mill cylinder), then isostatically press (pressurize at a rate of 9MPa / min, pressurize to 400MPa, hold pressure for 4min, compact size is 30mm diameter and 200mm length), and vacuum sinter (vacuum degree 1×10⁻⁶). -3 The process involved heating the material to 1000℃ at a rate of 9℃ / min and holding it at that temperature for 1.5 hours; machining it into a graphene copper alloy rod with a diameter of 30mm, a 13mm long external thread at one end, and thread parameters of M16×1.5mm; and preparing the powder using a plasma rotating electrode atomization method (vacuum degree 0.5×10). -2 (The process involves filling the air with 99% pure argon gas to a pressure of 1 atm, setting the motor speed to 13000 rpm, the plasma gun operating current to 1200 A, and the pushing speed to 1.8 mm / s) to obtain graphene-copper composite powder. S3. Weigh out 80 parts tungsten powder, 16 parts copper powder, 4 parts graphene copper composite powder, and 8 parts paraffin wax by mass and mix them in a ball mill (air pressure 3MPa, nitrogen protection, grinding balls are 5mm diameter tungsten copper balls, grinding speed 550rpm, grinding time 3h, material and grinding ball filling coefficient 1 / 3), cold press forming (temperature 25℃, pressurization rate 9MPa / min, pressurization to 900MPa, holding pressure for 2min), vacuum sintering (vacuum degree 4×10 -3 The process involved heating the material to 1020℃ at a rate of 6℃ / min and holding it for 1.5h, followed by re-pressing and re-firing (re-pressing was carried out in a steel mold at room temperature with a reduction rate of 3%, and after demolding, the re-pressed blank was placed in an alumina crucible, filled and compacted with pure alumina of 250 mesh, heated to 1310℃ at a rate of 15℃ / min and held for 1.5h, during which hydrogen or decomposed ammonia was passed through at a flow rate of 25L / h), and then cooled to 25℃ to obtain a graphene-reinforced tungsten-copper composite material (W80Cu20).

[0026] Compare with Example 1 This comparative example discloses a method for preparing a graphene-reinforced tungsten-copper composite material, which employs melt infiltration sintering and includes the following steps: S1. Graphene nickel plating: The graphene powder is ultrasonically cleaned in acetone solution for 5 minutes and dried in air. Then, at 60°C, the sample is cleaned in sodium salt solution containing sodium hydroxide for 15 minutes to remove residual grease and other substances adhering to the surface. Finally, it is immersed in 10% H2SO4 solution for 30 seconds to obtain an unoxidized surface. At the end of each cleaning step, it must be cleaned with distilled water and dried in air. The cleaned graphene powder is immediately immersed in chemical nickel plating solution at 90°C and pH 6 for 60 minutes. Then it is taken out, cleaned with water 3 times and then cleaned with anhydrous ethanol 2 times to obtain nickel-plated graphene powder. S2. Mixing: Weigh 24 parts copper powder, 70 parts tungsten powder and 6 parts nickel-plated graphene powder by weight and mechanically mix them in a high-energy ball mill for 60 minutes. Add 20 mL / kg of anhydrous ethanol during mixing to accelerate the mixing efficiency and avoid dust. S3. Forming: According to the size of the parts to be processed and the specific composition requirements, weigh a certain amount of the material mixed in step 2 (the amount weighed depends on the composition of the alloy and the size of the blank. The general calculation method is: the mass weighed = the volume of the blank × the density of the alloy of that composition × 85%) and put it into a steel mold (which determines the size and shape of the parts and is designed in advance) for cold pressing. The selected pressing pressure is 600MPa. S4. Solvent infiltration sintering: The green blank formed by cold pressing in step 3 is placed in a graphite boat. The copper block to be sintered (which can be processed from pure copper profiles or formed from pure copper powder) is placed on the top of the green blank (the specific amount is determined according to the calculation in Table 2). The surrounding area is filled with 100-mesh alumina sand. Then it is placed in a high-temperature atmosphere protection furnace and slowly heated (heating rate is 300℃ / h) to 1350℃. After holding at this temperature for 180 minutes, it is cooled with the furnace. The protective atmosphere used is argon, and the gas flow rate is 2L / h. S5. Post-treatment: The graphene-doped tungsten-copper alloy sintered in step 4 is placed in a solid sandblasting machine for surface treatment. The abrasive particles used are about 0.8 mm in diameter and the impact speed is 4 m / s. This removes some abrasive particles attached to the surface and improves the stress state of the surface, thus obtaining a graphene-reinforced tungsten-copper composite material (W70Cu30).

[0027] Compare with Example 2 This comparative example discloses a method for preparing a graphene-reinforced tungsten-copper composite material, which employs melt infiltration sintering and includes the following steps: S1. Graphene nickel plating: The graphene powder is ultrasonically cleaned in acetone solution for 5 minutes and dried in air. Then, at 60°C, the sample is cleaned in sodium salt solution containing sodium hydroxide for 15 minutes to remove residual grease and other substances adhering to the surface. Finally, it is immersed in 10% H2SO4 solution for 30 seconds to obtain an unoxidized surface. At the end of each cleaning step, it must be cleaned with distilled water and dried in air. The cleaned graphene powder is immediately immersed in chemical nickel plating solution at 90°C and pH 6 for 60 minutes. Then it is taken out, cleaned with water 3 times and then cleaned with anhydrous ethanol 2 times to obtain nickel-plated graphene powder. S2. Mixing: Weigh out 16 parts copper powder, 80 parts tungsten powder and 4 parts nickel-plated graphene powder by weight and mechanically mix them in a high-energy ball mill for 60 minutes. Add 20 mL / kg of anhydrous ethanol during mixing to accelerate the mixing efficiency and avoid dust. S3. Forming: According to the size of the parts to be processed and the specific composition requirements, weigh a certain amount of the material mixed in step 2 (the amount weighed depends on the composition of the alloy and the size of the blank. The general calculation method is: the mass weighed = the volume of the blank × the density of the alloy of that composition × 85%) and put it into a steel mold (which determines the size and shape of the parts and is designed in advance) for cold pressing. The selected pressing pressure is 600MPa. S4. Solvent infiltration sintering: The green blank formed by cold pressing in step 3 is placed in a graphite boat. The copper block to be sintered (which can be processed from pure copper profiles or formed from pure copper powder) is placed on the top of the green blank (the specific amount is determined according to the calculation in Table 2). The surrounding area is filled with 100-mesh alumina sand. Then it is placed in a high-temperature atmosphere protection furnace and slowly heated (heating rate is 300℃ / h) to 1350℃. After holding at this temperature for 180 minutes, it is cooled with the furnace. The protective atmosphere used is argon, and the gas flow rate is 2L / h. S5. Post-treatment: The graphene-doped tungsten-copper alloy sintered in step 4 is placed in a solid sandblasting machine for surface treatment. The abrasive particles used are about 0.8 mm in diameter and the impact speed is 4 m / s. This removes some abrasive particles attached to the surface and improves the stress state of the surface, thus obtaining a graphene-reinforced tungsten-copper composite material (W80Cu20).

[0028] Compare with Example 3 This comparative example discloses a method for preparing graphene-reinforced tungsten-copper composite materials, which employs multi-component sintering and includes the following steps: S1. Graphene oxide was dispersed in deionized water and subjected to ultrasonic treatment. The ultrasonic oscillation power was 800W, the ultrasonic oscillation time was 1h, the ultrasonic frequency was 40KHz, and the pH value was adjusted to 8.5 to obtain a graphene oxide suspension with a concentration of 1.5mg / mL. Dopamine hydrochloride was added to carry out the reaction. The mass ratio of graphene oxide to dopamine hydrochloride was 1:1. The reaction temperature was 60℃ and the reaction time was 28h to obtain a polydopamine-graphene suspension. S2. A copper-containing solution was added to the polydopamine-graphene suspension. The copper-containing solution was a mixed aqueous solution of copper chloride, ethylenediaminetetraacetic acid, boric acid, and dimethylamine borane. The concentrations of copper chloride, ethylenediaminetetraacetic acid, boric acid, and dimethylamine borane were 0.05 mol / L, ethylenediaminetetraacetic acid, boric acid, and dimethylamine borane were 0.15 mol / L, with a mass ratio of graphene oxide to copper chloride of 1:10. The mixture was stirred at room temperature and 500 r / min for 2 h. The precipitate was obtained by centrifugation, washed with deionized water, and then dried under vacuum at 60 °C to obtain the polydopamine / copper-modified graphene material. The polydopamine / copper-modified graphene material prepared in this comparative example, by mass percentage, comprised: 21.8% polydopamine-graphene and 78.2% copper. S3. Weigh out 3.6 parts of polydopamine / copper modified graphene material, 0.12 parts of aluminum powder, 0.78 parts of zirconium powder, 25.5 parts of copper powder, and 70 parts of tungsten powder by weight. Then, ball mill the polydopamine / copper modified graphene material, aluminum powder, and copper powder under an argon protective atmosphere at a speed of 400 r / min for 2 h. Then add tungsten powder and zirconium powder, and ball mill again under an argon protective atmosphere at a speed of 400 r / min for 4 h to obtain a mixture. S4. The mixture is pressed into a blank under a pressure of 350 MPa. Under an argon atmosphere, it is first heated to 800℃ at a heating rate of 20℃ / min and held for 3 hours for pre-sintering. Then, it is heated to 1300℃ at a heating rate of 10℃ / min and held for 1.5 hours for final sintering to obtain a graphene-reinforced tungsten copper composite material (W70Cu30).

[0029] Compare with Example 4 This comparative example discloses a method for preparing graphene-reinforced tungsten-copper composite materials, which employs multi-component sintering and includes the following steps: S1. Graphene oxide was dispersed in deionized water and subjected to ultrasonic treatment. The ultrasonic oscillation power was 800W, the ultrasonic oscillation time was 1h, the ultrasonic frequency was 40KHz, and the pH value was adjusted to 8.5 to obtain a graphene oxide suspension with a concentration of 1.5mg / mL. Dopamine hydrochloride was added to carry out the reaction. The mass ratio of graphene oxide to dopamine hydrochloride was 1:1. The reaction temperature was 60℃ and the reaction time was 28h to obtain a polydopamine-graphene suspension. S2. A copper-containing solution was added to the polydopamine-graphene suspension. The copper-containing solution was a mixed aqueous solution of copper chloride, ethylenediaminetetraacetic acid, boric acid, and dimethylamine borane. The concentrations of copper chloride, ethylenediaminetetraacetic acid, boric acid, and dimethylamine borane were 0.05 mol / L, ethylenediaminetetraacetic acid, boric acid, and dimethylamine borane were 0.15 mol / L, with a mass ratio of graphene oxide to copper chloride of 1:10. The mixture was stirred at room temperature and 500 r / min for 2 h. The precipitate was obtained by centrifugation, washed with deionized water, and then dried under vacuum at 60 °C to obtain the polydopamine / copper-modified graphene material. The polydopamine / copper-modified graphene material prepared in this comparative example, by mass percentage, comprised: 21.8% polydopamine-graphene and 78.2% copper. S3. Weigh out 2.4 parts of polydopamine / copper modified graphene material, 0.08 parts of aluminum powder, 0.52 parts of zirconium powder, 17 parts of copper powder, and 80 parts of tungsten powder by weight. Then, ball mill the polydopamine / copper modified graphene material, aluminum powder, and copper powder under an argon protective atmosphere at a speed of 400 r / min for 2 h. Then add tungsten powder and zirconium powder and ball mill again under an argon protective atmosphere at a speed of 400 r / min for 4 h to obtain a mixture. S4. The mixture is pressed into a blank under a pressure of 350 MPa. Under an argon atmosphere, it is first heated to 800℃ at a heating rate of 20℃ / min and held for 3 hours for pre-sintering. Then, it is heated to 1300℃ at a heating rate of 10℃ / min and held for 1.5 hours for final sintering to obtain a graphene-reinforced tungsten copper composite material (W80Cu20).

[0030] Compare with Example 5 Compared with Example 2, this comparative example uses nickel powder instead of graphene.

[0031] Compare with Example 6 Compared with Example 3, this comparative example does not involve repressing and refiring in step S3.

[0032] Performance testing Depend on Figure 4 Figure (a) shows the surface morphology of the composite material after arc ablation, which is uniform and crack-free, indicating that graphene and copper are well bonded. Figure 4 Figures (b) and (c) are magnified views of region A (copper phase enrichment region) and region B (tungsten phase enrichment region), respectively. Region A has a smooth surface, which proves that copper encapsulates graphene to form a protective layer. Region B has no tungsten carbide phase, which indicates that graphene and tungsten are effectively isolated. Figures (d) and (e) are EDS spectra of point A and point B. Point A is dominated by copper, and point B is dominated by tungsten, and there are no characteristic peaks of tungsten carbide, which verifies the mechanism of copper encapsulating graphene. Figure 5The image shows a SEM image of the fracture surface of a tungsten-copper composite material. From the fracture surface, tungsten particles are uniformly distributed around the copper in a network pattern. During fracture, the tungsten particles (indicated by white arrows) separate from the copper (indicated by yellow arrows), forming cracks. Crack propagation is hindered by the binder phase copper and graphene, which slows down crack growth. When the crack grows to the critical size, the binder phase copper undergoes ductile fracture. The whole process not only increases the strength of the composite material but also improves its ductility and toughness to a certain extent, partially overcoming the difficulty of the contradiction between strength and toughness in materials. Figure 6 Figures show the microstructure of graphene-tungsten-copper composite materials. Figures (a) and (b) show W60Cu40 prepared in Example 1, (c) and (d) show W70Cu30 prepared in Example 2, and (e) and (f) show W80Cu20 prepared in Example 3. As can be seen from the figures, with the increase of tungsten content, the tungsten particle distribution becomes denser, but the copper phase network structure remains intact, proving that the process is applicable to different ratios. Figure 7 and Figure 8 The images show the microstructure of Comparative Examples 5 and 6. The two images clearly show that the tungsten and copper phases are significantly separated, forming uneven regional distributions and exhibiting segregation. This verifies the success of the repressing and re-firing process, ensuring phase homogeneity and overcoming the difficulty of the traditional material's contradiction between strength and toughness.

[0033] Functional tests were performed on the graphene-reinforced tungsten-copper composite materials prepared in Examples 1-3 and Comparative Examples 1-4.

[0034] Density and relative density testing: Tested according to ASTM B962 standard; Hardness testing: Tested according to ASTM E10 standard; Electrical conductivity testing: conducted according to ASTM B193 standard; Bending strength testing: Tested according to ASTM E290 standard; Ablation rate testing: The test was conducted according to ASTM D495, "Standard Test Method for High Voltage, Low Current Dry Arc Resistance". The test results are shown in Tables 1, 2, and 3.

[0035] Table 1: Performance of W60Cu40 prepared in Example 1 category <![CDATA[Density (g / cm 3 )]]> relative density Hardness (HB) Electrical conductivity (%IACS) Flexural strength (MPa) Ablation rate (mg / 10C) Example 1 13.05 99.1% 150 56.3 703 1.12 Table 2: Performance of W70Cu30 prepared by different techniques category <![CDATA[Density (g / cm 3 )]]> relative density Hardness (HB) Electrical conductivity (%IACS) Flexural strength (MPa) Ablation rate (mg / 10C) Compare with Example 1 14.3 98.3% 197 44.6 893 1.79 Compare with Example 3 14.4 98.7% 211 47.5 1121 1.58 Compare with Example 5 14.35 98.5% 191 44.1 913 2.11 Example 2 14.53 99.2% 208 50.1 1103 0.76 Table 3: Performance of W80Cu20 prepared by different techniques category <![CDATA[Density (g / cm 3 )]]> relative density Hardness (HB) Electrical conductivity (%IACS) Flexural strength (MPa) Ablation rate (mg / 10C) Compare with Example 2 15.16 97.2% 231 40.2 1178.07 1.50 Compare with Example 4 15.28 98% 241 38.94 1241.57 1.37 Compare with Example 6 15.15 97% 221 36.7 1123 1.85 Example 3 15.20 99.0% 244 47.06 1223.14 0.32 As shown in Tables 1, 2, and 3, the graphene-reinforced tungsten-copper composite material prepared in the embodiments of this application has excellent mechanical properties. Compared with the two preparation methods of the comparative examples, the preparation method of the embodiments of this application has superior overall performance. From the test results, the overall performance of density, relative density, hardness, electrical conductivity, and bending strength is the best.

[0036] The above description is merely an example and illustration of the concept of this application. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the inventive concept or exceed the scope defined in the claims, they should all fall within the protection scope of this application.

Claims

1. A method of preparing a graphene-reinforced tungsten copper composite material, characterized by, The method comprises the following steps: S1, 40-50 parts by volume of graphene powder and 50-60 parts by volume of copper powder are stirred and mixed to obtain a premixed graphene copper composite powder; S2, 25-35 parts by volume of the premixed graphene copper composite powder and 2-4 parts by volume of anhydrous ethanol are mixed and ball milled, and then isostatic pressing, vacuum sintering, mechanical processing and powdering are performed to obtain a graphene copper composite powder; S3, 60-80 parts by mass of tungsten powder, 32-36 parts by mass of copper powder, 4-8 parts by mass of the graphene copper composite powder and 5-8 parts by mass of paraffin are mixed and ball milled, cold-pressed, vacuum sintered, re-pressed and re-sintered, and cooled to obtain a graphene reinforced tungsten copper composite material.

2. The method for preparing a graphene-reinforced tungsten-copper composite material according to claim 1, characterized in that, The graphene powder and the copper powder, the particle size of the copper powder is 30-50 μm, and the flake thickness of the graphene powder is ≤3 nm and the flake size is ≤100 μm.

3. The method for preparing a graphene-reinforced tungsten-copper composite material according to claim 1, characterized in that, The isostatic pressing is performed at a pressure increasing rate of 8-10 MPa / min, the pressure is increased to 350-450 MPa, and the pressure is maintained for 3-5 min, and the size of the compact is ≥30 mm in diameter and ≥200 mm in length.

4. The method for preparing a graphene-reinforced tungsten-copper composite material according to claim 1, characterized in that, The vacuum sintering in step S2 is performed at a vacuum degree of 1-1.5×10 -3 Pa, and the temperature is raised to 960-1000℃ at a temperature raising rate of 8-10℃ / min, and the temperature is kept for 1.5-2h.

5. The method for preparing a graphene-reinforced tungsten-copper composite material according to claim 1, characterized in that, The mechanical processing is performed to obtain a graphene copper alloy rod with a diameter of ≥30 mm, one end of which has an external thread with a length of 10-15 mm and a thread parameter of M16×1.5 mm.

6. The method for preparing a graphene-reinforced tungsten-copper composite material according to claim 1, characterized in that, The powder is made by plasma rotating electrode atomization method, vacuum degree <10 -2 Pa, pure argon gas with 99% purity, 1 atm, motor rotating speed 10000-15000 rpm, plasma gun working current 800-1600 A, pushing speed 1.3-2.2 mm / s.

7. The method for preparing a graphene-reinforced tungsten-copper composite material according to claim 1, characterized in that, The ball milling in step S3 is performed under the following conditions: the air pressure is 1-5 MPa, nitrogen protection is used, the grinding balls are tungsten copper balls with a diameter of 3-8 mm, the grinding speed is 500-600 rpm, the grinding time is 2-4 h, and the filling coefficient of the material and the grinding balls is 1 / 3-1 / 2.

8. The method for preparing a graphene-reinforced tungsten-copper composite material according to claim 1, characterized in that, The cold-pressing is performed at a temperature of 25-28℃, and the pressure is increased to 800-1000 MPa at a pressure increasing rate of 8-10 MPa / min, and the pressure is maintained for 2-3 min.

9. The method for preparing a graphene-reinforced tungsten-copper composite material according to claim 1, characterized in that, Step S3 vacuum sintering, vacuum degree is 3-5x10 -3 Pa, temperature is raised to 1000-1030℃ at 6-8℃ / min, and the temperature is kept for 1.5-2h, and the shrinkage rate is 1-3%.

10. The method for preparing a graphene-reinforced tungsten-copper composite material according to claim 1, characterized in that, The re-pressing and re-sintering are performed as follows: the re-pressing is performed at room temperature in a steel mold at a reduction rate of 2-4%, then the re-pressed compact is placed in a corundum crucible and buried and tamped with pure corundum with a particle size of 200-250 mesh, the temperature is increased to 1280-1350℃ at a temperature increasing rate of 10-20℃ / min, and the temperature is maintained for 1.5-2 h, and hydrogen gas or decomposed ammonia is passed through during the temperature maintaining process at a flow rate of 20-30 L / h.

Images