Method for preparing high-conductivity graphene brass

Abstract

The application discloses a preparation method of high-conductivity graphene brass. The silver-coated carbon nanotube is combined with graphene to form a one-dimensional+two-dimensional three-dimensional interpenetrating conductive framework, the interface resistance problem of the carbon nanotube and copper is solved by bridging with a silver layer, the carbon nanotube can be riveted on the surface of the graphene as a welding point, and then a high-efficiency electronic transmission highway is formed. After the framework is established, the wettability and the compatibility with copper powder are further improved by surface modification with phosphate and the like, and the formed composite material is obviously improved in conductivity and other performances.

Description

Technical Field

[0001] This invention relates to the field of materials technology, specifically to a method for preparing highly conductive graphene brass. Background Technology

[0002] Brass, a copper-based alloy with good electrical and thermal conductivity and machinability, such as conventional C26200 brass, is widely used in electronic components, conductive connectors, heat dissipation parts, and precision structural components. However, conventional C26200 brass has drawbacks, such as insufficient conductivity and low strength, making it difficult to meet the requirements of high-power, high-reliability service applications.

[0003] To improve the overall performance of brass, existing technologies mainly employ alloying, ceramic particle reinforcement, and carbon nanotube (CNT) or graphene reinforcement. Among these, carbon nanotubes and graphene possess ultra-high conductivity, high aspect ratio, high modulus, and high strength, making them ideal copper-based reinforcing phases. However, existing methods suffer from three major drawbacks: Poor dispersion of the reinforcing phase: Carbon nanotubes are prone to entanglement and aggregation, and graphene is prone to stacking of sheets. When directly mixed into the copper matrix, it is difficult to form a uniform network, which not only reduces the reinforcement efficiency, but also easily forms stress concentration defects and deteriorates the mechanical properties.

[0004] Weak interfacial bonding and high contact resistance: The chemical inertness of carbon nanotubes and graphene surfaces makes it easy to form voids, oxide layers or debonding interfaces with the copper substrate. This not only hinders load transfer and reduces strength, but also increases interfacial contact resistance and weakens conductivity, making it difficult to achieve a synergistic improvement in conductivity and strength, which needs to be improved. Summary of the Invention

[0005] To address at least one of the aforementioned technical deficiencies, the present invention provides the following technical solution: This application discloses a method for preparing highly conductive graphene brass, including the following steps: Step 1: Preparation of Ag@CNTs / graphene composite slurry Silver-plated carbon nanotubes and graphene powder are added to a solvent and processed to form a slurry; Step 2: Surface Modification Add dioleoyl phosphite, borate ester, and polytetrafluoroethylene to the slurry formed in step one, and sonicate at 55-65℃ for 2-4 hours. After solid-liquid separation, Ag@CNTs / graphene composite reinforced powder is obtained. Step 3: Mix with copper substrate The composite reinforced powder formed in step two is mixed with copper powder and then spray-dried. Step 4: Sinter the spray-dried composite powder to obtain the desired copper material.

[0006] Further, in step one: silver nitrate and reducing agent are added to the dispersion of carbon nanotubes, and ultrasonic treatment is performed at a temperature of 60-80℃ to reduce and deposit anions on the surface of carbon nanotubes. After drying, Ag@CNTs are obtained. The mass ratio of silver nitrate, reducing agent and carbon nanotubes is 6:6-10:3-5.

[0007] Further, in step one: the prepared Ag@CNTs and graphene are added to a solvent and subjected to high-energy ultrasonic treatment to form a slurry. The high-energy ultrasonic treatment parameters are: power 800-1000W, time 1-3h, and the mass ratio of carbon nanotubes to graphene is 1:2-4.

[0008] Further, in step two: the mass ratio of carbon nanotubes, dioleoyl phosphite, borate ester, and polytetrafluoroethylene is 3-5:3-5:1-2:0.5-1.

[0009] Further, in step three: the composite reinforced powder formed in step two is mixed with copper powder and ethanol, and stirred with a high-speed planetary stirrer at a speed of 1000-1500 r / min for 30-60 min, and then spray-dried. The mass ratio of carbon nanotubes to copper powder is 0.3-0.5:95-96.

[0010] Further, in step four: during sintering, the heating rate is 80-100℃ / min, the sintering temperature is 750-800℃, the axial pressure is 50-60MPa, and the holding time is 5-10min.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention first combines silver-coated carbon nanotubes with graphene to form a one-dimensional + two-dimensional three-dimensional interwoven conductive framework. The silver layer is used as a bridge to solve the interfacial resistance problem between carbon nanotubes and copper. At the same time, it can also serve as a solder point to rivet the carbon nanotubes onto the graphene surface, thereby forming a high-speed electron transport path. After the framework is established, surface modification with phosphate esters and other materials can further improve the wettability and compatibility with copper powder. The resulting composite material shows significant improvement in conductivity and other properties. Detailed Implementation

[0012] The present invention will be further described below with reference to specific embodiments.

[0013] Example 1 A method for preparing highly conductive graphene brass includes the following steps: Step 1: Preparation of Ag@CNTs / Graphene Composite Slurry Silver-plated carbon nanotubes and graphene powder are added to a solvent and processed to form a slurry.

[0014] Carbon nanotube pretreatment: Take multi-walled carbon nanotubes (diameter 10–20 nm, length 5–10 μm, purity ≥98%), add them to 50 times their weight of deionized water, and ultrasonically disperse for 30 min to obtain carbon nanotube dispersion.

[0015] Silver plating reaction: By mass, weigh silver nitrate and reducing agent (glucose) and add them to the above dispersion according to the ratio of silver nitrate: reducing agent: carbon nanotubes of 6:8:4; react in a 70℃ water bath and sonicate (300 W power) for 2 h to reduce and deposit silver ions on the surface of carbon nanotubes.

[0016] Drying: Centrifuge the silver-plated reaction solution (8000 rpm / min, 10 min), wash three times each with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12 h to obtain Ag@CNTs powder.

[0017] Slurry preparation: The mass ratio of carbon nanotubes to graphene is 1:3. Take Ag@CNTs and graphene (sheet diameter 5–10 μm, number of layers 5–10), and add N,N-dimethylformamide (DMF) at a mass ratio of 20 times the sum of the two. Disperse evenly by high-energy ultrasonication (900 W, 2 h) to obtain Ag@CNTs / graphene composite slurry.

[0018] Step 2: Surface Modification Dioleoyl phosphite, borate ester, and polytetrafluoroethylene were added to the slurry formed in step one. After ultrasonic reaction and solid-liquid separation, Ag@CNTs / graphene composite reinforced powder was obtained.

[0019] The mass ratio of carbon nanotubes: dioleoyl phosphite: borate ester: polytetrafluoroethylene is 4:4:1.5:0.8. Dioleoyl phosphite, borate ester, and polytetrafluoroethylene (particle size 0.2–0.5 μm) are added to the slurry formed in step one, with the polytetrafluoroethylene added when the reaction time is halfway through. The reaction is ultrasonically treated (200 W) at 60 °C for 3 h. After the reaction is completed, the mixture is centrifuged (8000 rpm / min, 10 min), washed three times with anhydrous ethanol, and vacuum dried at 60 °C for 12 h to obtain the composite reinforced powder.

[0020] Step 3: Mix with copper substrate The composite reinforced powder formed in step two is mixed with copper powder and then spray-dried.

[0021] The mass ratio of carbon nanotubes to copper powder (C26200 brass powder, particle size 5–10 μm) was 0.4:95.5. The composite reinforcing powder, copper powder, and anhydrous ethanol (1 / 2 the mass of copper powder) were added to a high-speed planetary mixer and stirred at 1200 rpm / min for 45 min. The mixture was then spray-dried (inlet air temperature 180℃, outlet air temperature 80℃) to obtain the composite powder.

[0022] Step 4: Sintering and Shaping The composite powder, which has been spray-dried and shaped, is sintered to obtain the desired copper material.

[0023] The composite powder was loaded into a graphite mold and hot-pressed under vacuum (0.6 Pa) with a heating rate of 90℃ / min, a sintering temperature of 780℃, an axial pressure of 55 MPa, and a holding time of 8 min. After cooling to room temperature in the furnace, the highly conductive graphene brass material was obtained.

[0024] Example 2 A method for preparing highly conductive graphene brass includes the following steps: Step 1: Preparation of Ag@CNTs / Graphene Composite Slurry Silver-plated carbon nanotubes and graphene powder are added to a solvent and processed to form a slurry.

[0025] Carbon nanotube pretreatment: Take multi-walled carbon nanotubes (diameter 10–20 nm, length 5–10 μm, purity ≥98%), add them to 50 times their weight of deionized water, and ultrasonically disperse for 30 min to obtain carbon nanotube dispersion.

[0026] Silver plating reaction: By mass, weigh silver nitrate and reducing agent (glucose) according to the ratio of silver nitrate: reducing agent: carbon nanotubes of 6:9:3 and add them to the above dispersion; react in a 70℃ water bath and sonicate (300 W power) for 2 h to reduce and deposit silver ions on the surface of carbon nanotubes.

[0027] Drying: Centrifuge the silver-plated reaction solution (8000 rpm / min, 10 min), wash three times each with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12 h to obtain Ag@CNTs powder.

[0028] Slurry preparation: The mass ratio of carbon nanotubes to graphene is 1:2.5. Take Ag@CNTs and graphene (sheet diameter 5–10 μm, number of layers 5–10), and add N,N-dimethylformamide (DMF) at a mass ratio of 20 times the sum of the two. Disperse evenly by high-energy ultrasonication (900 W, 2 h) to obtain Ag@CNTs / graphene composite slurry.

[0029] Step 2: Surface Modification Dioleoyl phosphite, borate ester, and polytetrafluoroethylene were added to the slurry formed in step one. After ultrasonic reaction and solid-liquid separation, Ag@CNTs / graphene composite reinforced powder was obtained.

[0030] The mass ratio of carbon nanotubes: dioleoyl phosphite: borate ester: polytetrafluoroethylene is 3:4:2:0.8. Dioleoyl phosphite, borate ester, and polytetrafluoroethylene (particle size 0.2–0.5 μm) are added to the slurry formed in step one. The polytetrafluoroethylene is added when the reaction time is halfway through. The reaction is ultrasonically treated (200 W) at 60 °C for 3 h. After the reaction is completed, the mixture is centrifuged (8000 rpm / min, 10 min), washed three times with anhydrous ethanol, and vacuum dried at 60 °C for 12 h to obtain composite reinforced powder.

[0031] Step 3: Mix with copper substrate The composite reinforced powder formed in step two is mixed with copper powder and then spray-dried.

[0032] The mass ratio of carbon nanotubes to copper powder (C26200 brass powder, particle size 5–10 μm) is 0.4:96. The composite reinforcing powder, copper powder, and anhydrous ethanol (1 / 2 the mass of copper powder) are added to a high-speed planetary mixer and stirred at 1200 rpm / min for 45 min. The mixture is then spray-dried (inlet air temperature 180℃, outlet air temperature 80℃) to obtain the composite powder.

[0033] Step 4: Sintering and Shaping The composite powder, which has been spray-dried and shaped, is sintered to obtain the desired copper material.

[0034] The composite powder was loaded into a graphite mold and hot-pressed under vacuum (0.6 Pa) with a heating rate of 90℃ / min, a sintering temperature of 760℃, an axial pressure of 55 MPa, and a holding time of 8 min. After cooling to room temperature in the furnace, the highly conductive graphene brass material was obtained.

[0035] Example 3 A method for preparing highly conductive graphene brass includes the following steps: Step 1: Preparation of Ag@CNTs / Graphene Composite Slurry Silver-plated carbon nanotubes and graphene powder are added to a solvent and processed to form a slurry.

[0036] Carbon nanotube pretreatment: Take multi-walled carbon nanotubes (diameter 10–20 nm, length 5–10 μm, purity ≥98%), add them to 50 times their weight of deionized water, and ultrasonically disperse for 30 min to obtain carbon nanotube dispersion.

[0037] Silver plating reaction: By mass, weigh silver nitrate and reducing agent (glucose) and add them to the above dispersion according to the ratio of silver nitrate: reducing agent: carbon nanotubes of 6:8:5; react in a 70℃ water bath and sonicate (300 W power) for 2 h to reduce and deposit silver ions on the surface of carbon nanotubes.

[0038] Drying: Centrifuge the silver-plated reaction solution (8000 rpm / min, 10 min), wash three times each with deionized water and anhydrous ethanol, and vacuum dry at 60℃ for 12 h to obtain Ag@CNTs powder.

[0039] Slurry preparation: The mass ratio of carbon nanotubes to graphene is 1:4. Take Ag@CNTs and graphene (sheet diameter 5–10 μm, number of layers 5–10), and add N,N-dimethylformamide (DMF) at a mass ratio of 20 times the sum of the two. Disperse evenly by high-energy ultrasonication (900 W, 2 h) to obtain Ag@CNTs / graphene composite slurry.

[0040] Step 2: Surface Modification Dioleoyl phosphite, borate ester, and polytetrafluoroethylene were added to the slurry formed in step one. After ultrasonic reaction and solid-liquid separation, Ag@CNTs / graphene composite reinforced powder was obtained.

[0041] The mass ratio of carbon nanotubes: dioleoyl phosphite: borate ester: polytetrafluoroethylene is 4:5:2:0.8. Dioleoyl phosphite, borate ester, and polytetrafluoroethylene (particle size 0.2–0.5 μm) are added to the slurry formed in step one. The polytetrafluoroethylene is added when the reaction time is halfway through. The reaction is ultrasonically treated (200 W) at 60 °C for 3 h. After the reaction is completed, the mixture is centrifuged (8000 rpm / min, 10 min), washed three times with anhydrous ethanol, and vacuum dried at 60 °C for 12 h to obtain composite reinforced powder.

[0042] Step 3: Mix with copper substrate The composite reinforced powder formed in step two is mixed with copper powder and then spray-dried.

[0043] The mass ratio of carbon nanotubes to copper powder (C26200 brass powder, particle size 5–10 μm) was 0.4:95.5. The composite reinforcing powder, copper powder, and anhydrous ethanol (1 / 2 the mass of copper powder) were added to a high-speed planetary mixer and stirred at 1200 rpm / min for 45 min. The mixture was then spray-dried (inlet air temperature 180℃, outlet air temperature 80℃) to obtain the composite powder.

[0044] Step 4: Sintering and Shaping The composite powder, which has been spray-dried and shaped, is sintered to obtain the desired copper material.

[0045] The composite powder was loaded into a graphite mold and hot-pressed under vacuum (0.6 Pa) with a heating rate of 90℃ / min, a sintering temperature of 780℃, an axial pressure of 55 MPa, and a holding time of 8 min. After cooling to room temperature in the furnace, the highly conductive graphene brass material was obtained.

[0046] Comparative Example 1 Compared with Example 1, the difference is that step one is omitted in this example. In this example, carbon nanotubes and graphene are directly mixed and reacted with dioleoyl phosphite, borate ester, polytetrafluoroethylene, etc., and silver powder is added in step three.

[0047] Comparative Example 2 The difference compared to Example 1 is that the carbon nanotubes are not silver-plated in step one of this example.

[0048] The materials prepared above were tested, and the results are shown in Table 1.

[0049] Table 1

[0050] It can be seen that the graphene brass material formed by the process of this invention exhibits excellent conductivity and compressive strength, making it suitable for widespread application.

[0051] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing high-conductivity graphene brass, characterized by, Includes the following steps: Step 1: Preparation of Ag@CNTs / graphene composite slurry Silver-plated carbon nanotubes and graphene powder are added to a solvent and processed to form a slurry; Step 2: Surface Modification Add dioleoyl phosphite, borate ester, and polytetrafluoroethylene to the slurry formed in step one, and sonicate at 55-65℃ for 2-4 hours. After solid-liquid separation, Ag@CNTs / graphene composite reinforced powder is obtained. Step 3: Mix with copper substrate The composite reinforced powder formed in step two is mixed with copper powder and then spray-dried. Step 4: Sinter the spray-dried composite powder to obtain the desired copper material.

2. The method for preparing highly conductive graphene brass as described in claim 1, characterized in that: Step 1: Add silver nitrate and reducing agent to the dispersion of carbon nanotubes, and sonicate at 60-80℃ to reduce and deposit anions on the surface of carbon nanotubes. After drying, Ag@CNTs are obtained. The mass ratio of silver nitrate, reducing agent and carbon nanotubes is 6:6-10:3-5.

3. The method for preparing highly conductive graphene brass as described in claim 1, characterized in that: Step 1: Add the prepared Ag@CNTs and graphene to a solvent and treat with high-energy ultrasound to form a slurry. High-energy ultrasound treatment parameters: power 800-1000W, time 1-3h, and the mass ratio of carbon nanotubes to graphene is 1:2-4.

4. The method for preparing highly conductive graphene brass as described in claim 1, characterized in that: Step 2: The mass ratio of carbon nanotubes, dioleoyl phosphite, borate ester, and polytetrafluoroethylene is 3-5:3-5:1-2:0.5-1.

5. The method for preparing highly conductive graphene brass as described in claim 1, characterized in that: Step 3: Mix the composite reinforced powder formed in Step 2 with copper powder and ethanol, and stir with a high-speed planetary stirrer at a speed of 1000-1500 r / min for 30-60 min. Then spray dry the mixture. The mass ratio of carbon nanotubes to copper powder is 0.3-0.5:95-96.

6. The method for preparing highly conductive graphene brass as described in claim 1, characterized in that: Step 4: During sintering, the heating rate is 80-100℃ / min, the sintering temperature is 750-800℃, the axial pressure is 50-60MPa, and the holding time is 5-10min.

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