A method for preparing single-walled carbon nanotube-copper composite materials
By modifying cobalt nanoparticles onto single-walled carbon nanotubes and using magnetic field-assisted technology, the problems of dispersion and uneven orientation in single-walled carbon nanotube-copper composites were solved, and composite materials with high electrical conductivity, high thermal conductivity and good mechanical properties were prepared.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANDONG CARBON XUN NEW MATERIALS CO LTD
- Filing Date
- 2025-10-11
- Publication Date
- 2026-05-26
AI Technical Summary
In the prior art, the wettability between single-walled carbon nanotubes and copper is insufficient, resulting in poor dispersion and uneven orientation, which limits the electrical and mechanical properties of the composite material.
Single-walled carbon nanotubes were prepared by a flotation catalysis method. After purification by acid washing and high-temperature repair, amorphous TiO2 composite cobalt nanoparticles were added under a nitrogen atmosphere. The single-walled carbon nanotubes were oriented in molten copper by magnetic field-assisted stirring and hot casting, forming strong covalent bonds.
The uniform dispersion and directional arrangement of single-walled carbon nanotubes in a copper matrix were achieved, which improved the electrical conductivity, thermal conductivity and mechanical properties of the composite material.
Smart Images
Figure CN121272249B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of copper composite material technology, specifically relating to a method for preparing single-walled carbon nanotube-copper composite material. Background Technology
[0002] Copper and copper alloys have been widely used in various modern industrial fields. However, with the development of industrial technology, copper and copper alloys can no longer meet the requirements of some fields for high electrical conductivity, high temperature performance, and mechanical properties. Therefore, metal composite materials have become a research hotspot. Single-walled carbon nanotubes are considered an ideal reinforcement for metal matrix composites due to their excellent mechanical strength, high electrical conductivity, and high thermal conductivity.
[0003] The prospects for single-walled carbon nanotube copper-based composite materials are broad. Traditional preparation methods mainly include chemical vapor deposition and powder metallurgy. Powder metallurgy is the most commonly used preparation method for carbon nanotube copper-based composite materials, which mainly includes mechanical mixing, ball milling, hot pressing sintering, and spark plasma sintering. Chemical vapor deposition involves directly growing carbon nanotubes on copper powder or copper substrate and then hot pressing them into shape.
[0004] Currently, traditional preparation techniques face several bottlenecks: First, insufficient wettability between single-walled carbon nanotubes (SUVs) and copper leads to poor dispersion of SUVs. In copper-carbon composites obtained through chemical vapor deposition and hot pressing, the carbon phase is mainly distributed on the surface of the copper foil, requiring multi-layer stacking to improve conductivity. Materials prepared by this method typically exhibit a distinct layered structure, which limits their application range to some extent. Second, the orientation of SUVs within the copper matrix is uneven. As a one-dimensional material, the orientation of SUVs significantly affects their conductivity. If the SUVs are aligned axially, electrons will migrate along the axial direction, achieving room-temperature superconductivity. Chinese patent CN111118583A uses nickel plating to orient the carbon nanotubes in a magnetic field, but the bond between the carbon nanotubes and copper is weak, and the prepared copper plate and carbon nanotubes are stacked layer by layer, preventing uniform dispersion of the carbon nanotubes within the copper matrix. Therefore, how to disperse and orient single-walled carbon nanotubes in a copper matrix is the key to improving the preparation method of single-walled carbon nanotube-copper composite materials. Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing single-walled carbon nanotube-copper composite materials to solve the above-mentioned technical problems.
[0006] To achieve the above-mentioned technical objectives, the technical solution of the present invention is as follows:
[0007] A method for preparing a single-walled carbon nanotube-copper composite material includes the following steps:
[0008] S1. Single-walled carbon nanotubes were prepared using a flotation catalysis method, and the single-walled carbon nanotubes were then subjected to acid washing and high-temperature purification.
[0009] S2. Under a nitrogen atmosphere, amorphous TiO2 composite cobalt nanoparticles modified with single-walled carbon nanotubes were added to molten copper and ultrasonically stirred for 0.5-1 h. After mixing, magnetic field-assisted stirring was performed with the stirring direction parallel to the magnetic field direction. The temperature of the molten copper was reduced to 1100-1150℃ and stirred for 30 min.
[0010] S3. Using hot casting, molten copper is rapidly solidified and hot-drawn into copper rods. During this process, magnetic field assistance is continued. The direction of the magnetic field is parallel to the stirring direction of the molten copper in the melt system and the flow direction of the molten copper in the mold heating system. The mold heating system continuously casts the copper rods along the direction of the magnetic field to obtain single-walled carbon nanotube-copper composite materials.
[0011] As a further improvement, in step S1, the acid washing and high-temperature repair and purification steps are as follows: the single-walled carbon nanotubes are acid washed and purified with a mixed solution of hydrogen peroxide and dilute hydrochloric acid, reacted at 60°C for 1 hour, and then washed with deionized water to obtain crude single-walled carbon nanotubes; wherein the volume ratio of hydrogen peroxide to dilute hydrochloric acid is 1:1; the crude single-walled carbon nanotubes are heat-treated at 1800°C below 90 Pa in a vacuum sintering furnace for 4 hours, and then cooled under vacuum to obtain purified single-walled carbon nanotubes.
[0012] As a further improvement, in step S2, the method for preparing the amorphous TiO2 composite cobalt nanoparticle-modified single-walled carbon nanotubes is as follows: the cobalt nanoparticle-modified single-walled carbon nanotubes are dispersed in anhydrous ethanol, sonicated for 30 min, and tetrabutyl titanate is slowly added dropwise while stirring for 0.5-1 h; under vigorous stirring, a catalyst solution is slowly added dropwise while stirring at room temperature for 12-24 h, the product is collected by filtration, washed three times with anhydrous ethanol, and vacuum dried at 60-80℃ for 12 h to obtain the final product.
[0013] As a further improvement, the mass ratio of the cobalt nanoparticle-modified single-walled carbon nanotubes to tetrabutyl titanate is 1:1.5~3; the catalyst solution is prepared by mixing deionized water and anhydrous ethanol, adding dilute nitric acid dropwise, and mixing well to obtain the catalyst solution; wherein the mass ratio of deionized water, anhydrous ethanol and dilute nitric acid is 1:2:0.05; the catalyst solution is slowly added at a rate of 1~2 drops / second.
[0014] As a further improvement, the preparation method of the cobalt nanoparticle-modified single-walled carbon nanotubes is as follows: gradient oxidized carbon nanotubes are dispersed in deionized water, sonicated for 0.5-1 h, and under a nitrogen atmosphere, CoCl2 solution is added, stirred for 30 min, and the pH is adjusted to 9-10; under vigorous stirring, NaBH4 solution is added dropwise, and the reaction continues for 2 h; after the reaction is completed, the product is separated by precipitation with a magnet, washed 3 times with anhydrous ethanol, and vacuum dried at 60℃ for 12 h to obtain the product.
[0015] As a further improvement, the mass ratio of the gradient oxidized carbon nanotubes to deionized water is 1:20, the concentration of the CoCl2 solution is 0.1 mol / L, the concentration of the NaBH4 solution is 0.2 mol / L, and the volume ratio of the CoCl2 solution, NaBH4 solution, and deionized water is 2:1:4.
[0016] As a further improvement, the method for preparing the gradient oxidized carbon nanotubes is as follows: prepare a mixed acid solution containing concentrated sulfuric acid and concentrated nitric acid, with a volume ratio of concentrated sulfuric acid to concentrated nitric acid of 3:1; add the purified single-walled carbon nanotubes to the mixed acid solution; sonicate at 40°C for 30 min; cool to 20°C and sonicate for 30 min; filter; collect the precipitate; wash with deionized water until neutral; and vacuum dry to obtain the final product.
[0017] As a further improvement, in steps S2 and S3, the specific method of magnetic field assistance is as follows: an electromagnetic coil is wound around the outside of the melt system and the mold heating system, and a directional magnetic field is added, with the magnetic field direction, stirring direction and molten copper flow direction in the mold heating system being parallel.
[0018] As a further improvement, the external magnetic field strength of the melt system is 0.5~1T, and the external magnetic field strength of the casting heating system is 1~2T.
[0019] As a further improvement, in step S3, the process parameters of the hot continuous casting method are: the temperature of the melt system is 1100~1150℃, the temperature at the mold outlet is 1100~1150℃, and the casting speed is 10~15mm / min.
[0020] Due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows:
[0021] This invention employs gradient acid oxidation to introduce active oxygen-containing functional groups, then anchors cobalt nanoparticles at the oxidation sites, forming a cobalt nanoparticle distribution on single-walled carbon nanotubes (SUVs), thus endowing the SUVs with magnetic responsiveness. A sol-gel method is used to coat an amorphous titanium dioxide thin layer as a precursor. Upon addition of molten copper, the titanium dioxide undergoes a carbothermic reaction to generate an ultrathin, continuous, and dense titanium carbide layer. The catalytic effect of the cobalt nanoparticles on the SUV surface lowers the formation temperature of the titanium carbide layer and confines the carbide reaction to the surface of the SUVs, preventing excessive erosion of the SUVs by active titanium, which could damage the SUV walls and affect their superior performance. The titanium carbide layer is strongly covalently bonded to the SUVs on one side and forms a stable metallurgical bond with the copper matrix on the other side, enhancing the interfacial bonding between the SUVs and copper and improving the strength and high conductivity of the composite material.
[0022] This invention utilizes cobalt nanoparticles modified on carbon nanotubes as a magnetic response source, applying a high-intensity directional magnetic field throughout the entire process of melt composite and continuous casting. The magnetic field force drives the carbon nanotubes with high aspect ratio to overcome Brownian motion and turbulence interference, ensuring that their long axes are precisely aligned along the magnetic field direction. This allows the single-walled carbon nanotubes to maintain a high degree of orientation within the copper matrix. During the magnetic field orientation process, lowering the temperature of the molten copper increases its viscosity, reduces the Brownian motion of the single-walled carbon nanotubes, and decreases the deflection amplitude of their thermal disturbance. This creates a spatial locking effect on the oriented single-walled carbon nanotubes, enabling them to maintain a uniform orientation in the magnetic field. This oriented structure results in a significant anisotropic improvement in the mechanical, electrical, and thermal properties of the composite material along the axial direction.
[0023] This invention employs a method of mixing single-walled carbon nanotubes with molten copper, utilizing the fluidity and permeability of liquid copper to enable the single-walled carbon nanotubes to be uniformly dispersed in the molten copper. Compared with solid ball milling and powder metallurgy, this invention can achieve uniform dispersion of single-walled carbon nanotubes while avoiding structural damage.
[0024] The single-walled carbon nanotube-copper composite material prepared by this invention has single-walled carbon nanotubes that are uniformly dispersed in copper and are oriented along the axial direction. As a result, the composite material has good mechanical properties, electrical conductivity and thermal conductivity. Attached Figure Description
[0025] Figure 1 This is a SEM image of the single-walled carbon nanotubes modified with amorphous TiO2 composite cobalt nanoparticles prepared in Example 1.
[0026] Figure 2 These are SEM scan images of the carbon nanotube-copper composite material prepared in Example 1;
[0027] Figure 3 This is a SEM scan image of the carbon nanotube-copper composite material prepared in Comparative Example 1. Detailed Implementation
[0028] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.
[0029] Example 1: A method for preparing a single-walled carbon nanotube-copper composite material, comprising the following steps:
[0030] S1. Preparation of crude single-walled carbon nanotubes using a flotation catalytic method: Using n-hexane as the carbon source, a mixed solution of n-hexane, ferrocene (catalyst), and thiophene was catalytically cracked in a vertical furnace under a nitrogen atmosphere. The cracking temperature was 1100℃, the concentration of ferrocene was 0.50 g / 100 mL, the concentration of thiophene was 0.42 mL / 100 mL, the cracking time was 1 h, and nitrogen gas was purged for cooling after the reaction was completed.
[0031] S2. Take 80g of the above crude single-walled carbon nanotubes, add 0.5L of a mixed solution of hydrogen peroxide and dilute hydrochloric acid, with a volume ratio of 1:1 and a concentration of 2mol / L. React at 60℃ for 1h, filter, wash the filter residue three times with deionized water, and perform vacuum sintering. The vacuum degree is controlled at 90Pa and the temperature is controlled at 1800℃. After heat treatment for 4h, vacuum cool.
[0032] S3. Add 50g of purified single-walled carbon nanotubes to a three-necked flask containing a mixture of 0.5L concentrated nitric acid and concentrated sulfuric acid. Stir and mix well. The volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1, the concentration of concentrated nitric acid is 68%, and the concentration of concentrated sulfuric acid is 95%. Place the flask in an oil bath at 40℃ and sonicate for 30min. Cool down to 20℃ and sonicate for another 30min. After the reaction is complete, filter and collect the precipitate. Wash with deionized water until the filtrate is neutral. Place the product in a vacuum drying oven at 60℃ and dry for 12 hours to obtain graded oxidized carbon nanotubes.
[0033] S4. Disperse 10g of graded carbon nanotubes in 200mL of deionized water and sonicate at 400W for 1h until a uniform black dispersion is formed; transfer the dispersion to a three-necked flask and add 0.1mol / L [acid / water] under nitrogen protection. 100 mL of solution was stirred magnetically for 30 minutes to allow the solution to settle. The solution is fully adsorbed onto the surface of carbon nanotubes; the pH of the mixture is adjusted to 10 with NaOH solution, and freshly prepared 0.2 mol / L sodium hydroxide solution is slowly added dropwise using a constant pressure dropping funnel while stirring vigorously. After adding 50 mL of solution, the reaction continued for 2 h under nitrogen protection and at room temperature. After the reaction was completed, the product was separated by precipitation with the assistance of a magnet. The product was washed three times with anhydrous ethanol and dried in a vacuum drying oven at 60 °C for 12 h to obtain single-walled carbon nanotubes modified with cobalt nanoparticles.
[0034] S5. In a nitrogen-filled glove box, 5g of cobalt nanoparticle-modified single-walled carbon nanotubes were dispersed in 100ml of anhydrous ethanol and sonicated for 30min to form a uniform dispersion. The dispersion was transferred to a dry flask, and 7.5g of tetrabutyl titanate was slowly added using a dropping funnel while continuously stirring for 1h to ensure homogeneity. 10mL of deionized water and 20ml of anhydrous ethanol were mixed, and 0.5mL of 1mol / L dilute nitric acid was added and mixed well to prepare the catalyst solution. While stirring vigorously, the catalyst solution was added dropwise to the dispersion at a very slow rate (1-2 drops / second) using a dropping funnel. After the addition was complete, stirring was continued at room temperature for 24h. After the reaction was completed, the product was collected by filtration, washed three times with anhydrous ethanol, and dried in a vacuum drying oven at 80℃ for 12h to obtain amorphous TiO2 composite cobalt nanoparticle-modified single-walled carbon nanotubes.
[0035] S6. Under a nitrogen atmosphere, add amorphous TiO2 composite cobalt nanoparticles modified with single-walled carbon nanotubes to molten copper (concentration of 0.5wt%) and ultrasonically stir for 30 minutes to mix them evenly. After mixing, perform magnetic field-assisted stirring. Wrap an electromagnetic coil around the high-temperature protective sleeve of the melt system and the casting heating system to add a directional magnetic field to the equipment. The magnetic field strength is 1T. The stirring direction and the magnetic field direction are parallel to the flow direction of molten copper in the casting heating system. The temperature of molten copper is controlled at 1150℃ during stirring, and stirring is carried out for 30 minutes.
[0036] S7. Using hot continuous casting, molten copper is rapidly solidified and hot-drawn into copper rods. The casting heating system performs continuous casting of copper rods along the magnetic field direction. The magnetic field strength is 2T, the casting outlet temperature is controlled at 1100℃, the casting speed is 15mm / min, and the cooling distance is 50mm, thus obtaining a single-walled carbon nanotube-copper composite material.
[0037] The SEM image of the amorphous TiO2 composite cobalt nanoparticle-modified single-walled carbon nanotubes prepared in this embodiment is shown below. Figure 1 As shown.
[0038] Example 2: A method for preparing a single-walled carbon nanotube-copper composite material, comprising the following steps:
[0039] S1. Preparation of crude single-walled carbon nanotubes using a flotation catalytic method: Using n-hexane as the carbon source, a mixed solution of n-hexane, ferrocene (catalyst), and thiophene was catalytically cracked in a vertical furnace under a nitrogen atmosphere. The cracking temperature was 1100℃, the concentration of ferrocene was 0.50 g / 100 mL, the concentration of thiophene was 0.42 mL / 100 mL, the cracking time was 1 h, and nitrogen gas was purged for cooling after the reaction was completed.
[0040] S2. Take 80g of the above crude single-walled carbon nanotubes, add 0.5L of a mixed solution of hydrogen peroxide and dilute hydrochloric acid, with a volume ratio of 1:1 and a concentration of 2mol / L. React at 60℃ for 1h, filter, wash the filter residue three times with deionized water, and perform vacuum sintering. The vacuum degree is controlled at 90Pa and the temperature is controlled at 1800℃. After heat treatment for 4h, vacuum cool.
[0041] S3. Add 50g of purified single-walled carbon nanotubes to a three-necked flask containing a mixture of 0.5L concentrated nitric acid and concentrated sulfuric acid. Stir and mix well. The volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1, the concentration of concentrated nitric acid is 68%, and the concentration of concentrated sulfuric acid is 95%. Place the flask in an oil bath at 40℃ and sonicate for 30min. Cool down to 20℃ and sonicate for 30min. After the reaction is complete, filter and collect the precipitate. Wash with deionized water until the filtrate is neutral. Place the product in a vacuum drying oven at 60℃ and dry for 12 hours to obtain gradient oxidized carbon nanotubes.
[0042] S4. Disperse 10g of graded carbon nanotubes in 200mL of deionized water and sonicate at 400W for 30min until a uniform black dispersion is formed; transfer the dispersion to a three-necked flask and, under nitrogen protection, add 0.1mol / L of [a specific chemical / material]. 100 mL of solution was stirred magnetically for 30 minutes to allow the solution to settle. The solution is fully adsorbed onto the surface of carbon nanotubes; the pH of the mixture is adjusted to 9 with NaOH solution, and freshly prepared 0.2 mol / L sodium hydroxide solution is slowly added dropwise using a constant pressure dropping funnel while stirring vigorously. After adding 50 mL of solution, the reaction continued for 2 h under nitrogen protection and at room temperature. After the reaction was completed, the product was separated by precipitation with the assistance of a magnet. The product was washed three times with anhydrous ethanol and dried in a vacuum drying oven at 60 °C for 12 h to obtain single-walled carbon nanotubes modified with cobalt nanoparticles.
[0043] S5. In a nitrogen-filled glove box, 5g of cobalt nanoparticle-modified single-walled carbon nanotubes were dispersed in 100ml of anhydrous ethanol and sonicated for 30min to form a uniform dispersion. The dispersion was transferred to a dry flask, and 15g of tetrabutyl titanate was slowly added using a dropping funnel while continuously stirring for 30min until homogeneous. 10mL of deionized water and 20ml of anhydrous ethanol were mixed, and 0.5mL of 1mol / L dilute nitric acid was added and mixed well to prepare the catalyst solution. While stirring vigorously, the catalyst solution was added dropwise to the dispersion at a very slow rate (1-2 drops / second) using a dropping funnel. After the addition was complete, stirring was continued at room temperature for 12h. After the reaction was completed, the product was collected by filtration, washed three times with anhydrous ethanol, and dried in a vacuum drying oven at 60℃ for 12h to obtain amorphous TiO2 composite cobalt nanoparticle-modified single-walled carbon nanotubes.
[0044] S6. Under a nitrogen atmosphere, add amorphous TiO2 composite cobalt nanoparticles modified with single-walled carbon nanotubes to molten copper (concentration of 0.5wt%) and ultrasonically stir for 1 hour to mix them evenly. After mixing, perform magnetic field-assisted stirring. Wrap an electromagnetic coil around the high-temperature protective sleeve of the melt system and the casting heating system to add a directional magnetic field to the equipment. The magnetic field strength is 0.5T. The stirring direction and the magnetic field direction are parallel to the flow direction of molten copper in the casting heating system. The temperature of molten copper is controlled at 1100℃ during stirring, and stirring is carried out for 30 minutes.
[0045] S7. Molten copper is rapidly solidified and hot-drawn into copper rods using hot continuous casting. The casting heating system is used to continuously cast the copper rods along the magnetic field direction. The magnetic field strength is 1T, the casting outlet temperature is controlled at 1150℃, the casting speed is 10mm / min, and the cooling distance is 50mm to obtain single-walled carbon nanotube-copper composite material.
[0046] Comparative Example 1: A method for preparing a single-walled carbon nanotube-copper composite material, differing from Example 1 in that it does not involve magnetic field orientation treatment, and includes the following steps:
[0047] S1. Preparation of crude single-walled carbon nanotubes using a flotation catalytic method: Using n-hexane as the carbon source, a mixed solution of n-hexane, ferrocene (catalyst), and thiophene was catalytically cracked in a vertical furnace under a nitrogen atmosphere. The cracking temperature was 1100℃, the concentration of ferrocene was 0.50 g / 100 mL, the concentration of thiophene was 0.42 mL / 100 mL, the cracking time was 1 h, and nitrogen gas was purged for cooling after the reaction was completed.
[0048] S2. Take 80g of the above crude single-walled carbon nanotubes, add 0.5L of a mixed solution of hydrogen peroxide and dilute hydrochloric acid, with a volume ratio of 1:1 and a concentration of 2mol / L. React at 60℃ for 1h, filter, wash the filter residue three times with deionized water, and perform vacuum sintering. The vacuum degree is controlled at 90Pa and the temperature is controlled at 1800℃. After heat treatment for 4h, vacuum cool.
[0049] S3. Gradient oxidation of carbon nanotubes in mixed acid: 50g of purified single-walled carbon nanotubes were added to a three-necked flask containing 0.5L of a mixture of concentrated nitric acid and concentrated sulfuric acid. The mixture was stirred and mixed thoroughly. The volume ratio of concentrated sulfuric acid to concentrated nitric acid was 3:1, the concentration of concentrated nitric acid was 68%, and the concentration of concentrated sulfuric acid was 95%. The flask was placed in an oil bath at 40℃ and sonicated for 30min. The temperature was then lowered to 20℃ and sonicated for another 30min. After the reaction was completed, the precipitate was collected by vacuum filtration and washed with deionized water until the filtrate was neutral. The product was then dried in a vacuum drying oven at 60℃ for 12 hours to obtain gradient oxidized carbon nanotubes.
[0050] S4. Disperse 10g of graded carbon nanotubes in 200mL of deionized water and sonicate at 400W for 1h until a uniform black dispersion is formed; transfer the dispersion to a three-necked flask and add 0.1mol / L [acid / water] under nitrogen protection. 100 mL of solution was stirred magnetically for 30 minutes to allow the solution to settle. The solution is fully adsorbed onto the surface of carbon nanotubes; the pH of the mixture is adjusted to 10 with NaOH solution, and freshly prepared 0.2 mol / L sodium hydroxide solution is slowly added dropwise using a constant pressure dropping funnel while stirring vigorously. After adding 50 mL of solution, the reaction continued for 2 h under nitrogen protection and at room temperature. After the reaction was completed, the product was separated by precipitation with the assistance of a magnet. The product was washed three times with anhydrous ethanol and dried in a vacuum drying oven at 60 °C for 12 h to obtain single-walled carbon nanotubes modified with cobalt nanoparticles.
[0051] S5. In a nitrogen-filled glove box, 5g of cobalt nanoparticle-modified single-walled carbon nanotubes were dispersed in 100ml of anhydrous ethanol and sonicated for 30min to form a uniform dispersion. The dispersion was transferred to a dry flask, and 7.5g of tetrabutyl titanate was slowly added using a dropping funnel while continuously stirring for 1h to ensure homogeneity. 10mL of deionized water and 20ml of anhydrous ethanol were mixed, and 0.5mL of 1mol / L dilute nitric acid was added and mixed well to prepare the catalyst solution. While stirring vigorously, the catalyst solution was added dropwise to the dispersion at a very slow rate (1-2 drops / second) using a dropping funnel. After the addition was complete, stirring was continued at room temperature for 24h. After the reaction was completed, the product was collected by filtration, washed three times with anhydrous ethanol, and dried in a vacuum drying oven at 80℃ for 12h to obtain amorphous TiO2 composite cobalt nanoparticle-modified single-walled carbon nanotubes.
[0052] S6. Under a nitrogen atmosphere, amorphous TiO2 composite cobalt nanoparticles modified with single-walled carbon nanotubes were added to molten copper (concentration of 0.5 wt%) and ultrasonically stirred for 30 min to mix them evenly. The molten copper was rapidly solidified and hot-drawn into copper rods using a hot casting method. The mold exit temperature was controlled at 1100℃, the casting speed was 15 mm / min, and the cooling distance was 50 mm to obtain a single-walled carbon nanotube-copper composite material.
[0053] Comparative Example 2: A method for preparing a single-walled carbon nanotube-copper composite material, which differs from Example 1 in that titanium oxide is not added, and includes the following steps:
[0054] S1. Preparation of crude single-walled carbon nanotubes using a flotation catalytic method: Using n-hexane as the carbon source, a mixed solution of n-hexane, ferrocene (catalyst), and thiophene was catalytically cracked in a vertical furnace under a nitrogen atmosphere. The cracking temperature was 1100℃, the concentration of ferrocene was 0.50 g / 100 mL, the concentration of thiophene was 0.42 mL / 100 mL, the cracking time was 1 h, and nitrogen gas was purged for cooling after the reaction was completed.
[0055] S2. Take 80g of the above crude single-walled carbon nanotubes, add 0.5L of a mixed solution of hydrogen peroxide and dilute hydrochloric acid, with a volume ratio of 1:1 and a concentration of 2mol / L. React at 60℃ for 1h, filter, wash the filter residue three times with deionized water, and perform vacuum sintering. The vacuum degree is controlled at 90Pa and the temperature is controlled at 1800℃. After heat treatment for 4h, vacuum cool.
[0056] S3. Gradient oxidation of carbon nanotubes in mixed acid: 50g of purified single-walled carbon nanotubes were added to a three-necked flask containing 0.5L of a mixture of concentrated nitric acid and concentrated sulfuric acid. The mixture was stirred and mixed thoroughly. The volume ratio of concentrated sulfuric acid to concentrated nitric acid was 3:1, the concentration of concentrated nitric acid was 68%, and the concentration of concentrated sulfuric acid was 95%. The flask was placed in an oil bath at 40℃ and sonicated for 30min. The temperature was then lowered to 20℃ and sonicated for another 30min. After the reaction was completed, the precipitate was collected by vacuum filtration and washed with deionized water until the filtrate was neutral. The product was then dried in a vacuum drying oven at 60℃ for 12 hours to obtain gradient oxidized carbon nanotubes.
[0057] S4. Disperse 10g of graded carbon nanotubes in 200mL of deionized water and sonicate at 400W for 1h until a uniform black dispersion is formed; transfer the dispersion to a three-necked flask and add 0.1mol / L [acid / water] under nitrogen protection. 100 mL of solution was stirred magnetically for 30 minutes to allow the solution to settle. The solution is fully adsorbed onto the surface of carbon nanotubes; the pH of the mixture is adjusted to 10 with NaOH solution, and freshly prepared 0.2 mol / L sodium hydroxide solution is slowly added dropwise using a constant pressure dropping funnel while stirring vigorously. After adding 50 mL of solution, the reaction continued for 2 h under nitrogen protection and at room temperature. After the reaction was completed, the product was separated by precipitation with the assistance of a magnet. The product was washed three times with anhydrous ethanol and dried in a vacuum drying oven at 60 °C for 12 h to obtain single-walled carbon nanotubes modified with cobalt nanoparticles.
[0058] S5. Under a nitrogen atmosphere, add cobalt nanoparticle-modified single-walled carbon nanotubes to molten copper (concentration of 0.5wt%) and ultrasonically stir for 30 minutes to mix them evenly. After mixing, perform magnetic field-assisted stirring. Wrap an electromagnetic coil around the high-temperature protective sleeve of the melt system and the casting heating system to add a directional magnetic field to the equipment. The magnetic field strength is 1T. The stirring direction and the magnetic field direction are parallel to the flow direction of molten copper in the casting heating system. The temperature of molten copper is controlled at 1150℃ during stirring, and stirring is carried out for 30 minutes.
[0059] S6. Using hot continuous casting, molten copper is rapidly solidified and hot-drawn into copper rods. The casting heating system performs continuous casting of copper rods along the magnetic field direction. The magnetic field strength is 2T, the casting outlet temperature is controlled at 1100℃, the casting speed is 15mm / min, and the cooling distance is 50mm, thus obtaining a single-walled carbon nanotube-copper composite material.
[0060] Comparative Example 3: A method for preparing a single-walled carbon nanotube-copper composite material, differing from Example 1 in that no cobalt nanoparticle treatment was performed, and no magnetic field treatment was added. The method includes the following steps:
[0061] S1. Preparation of crude single-walled carbon nanotubes using a flotation catalytic method: Using n-hexane as the carbon source, a mixed solution of n-hexane, ferrocene (catalyst), and thiophene was catalytically cracked in a vertical furnace under a nitrogen atmosphere. The cracking temperature was 1100℃, the concentration of ferrocene was 0.50 g / 100 mL, the concentration of thiophene was 0.42 mL / 100 mL, the cracking time was 1 h, and nitrogen gas was purged for cooling after the reaction was completed.
[0062] S2. Take 80g of the above crude single-walled carbon nanotubes, add 0.5L of a mixed solution of hydrogen peroxide and dilute hydrochloric acid, with a volume ratio of 1:1 and a concentration of 2mol / L. React at 60℃ for 1h, filter, wash the filter residue three times with deionized water, and perform vacuum sintering. The vacuum degree is controlled at 90Pa and the temperature is controlled at 1800℃. After heat treatment for 4h, vacuum cool.
[0063] S3. Gradient oxidation of carbon nanotubes in mixed acid: 50g of purified single-walled carbon nanotubes were added to a three-necked flask containing 0.5L of a mixture of concentrated nitric acid and concentrated sulfuric acid. The mixture was stirred and mixed thoroughly. The volume ratio of concentrated sulfuric acid to concentrated nitric acid was 3:1, the concentration of concentrated nitric acid was 68%, and the concentration of concentrated sulfuric acid was 95%. The flask was placed in an oil bath at 40℃ and sonicated for 30min. The temperature was then lowered to 20℃ and sonicated for another 30min. After the reaction was completed, the precipitate was collected by vacuum filtration and washed with deionized water until the filtrate was neutral. The product was then dried in a vacuum drying oven at 60℃ for 12 hours to obtain gradient oxidized carbon nanotubes.
[0064] S4. In a nitrogen-filled glove box, 5g of graded-oxidation carbon nanotubes were dispersed in 100mL of anhydrous ethanol and sonicated for 30min to form a uniform dispersion. The dispersion was transferred to a dry flask, and 7.5g of tetrabutyl titanate was slowly added using a dropping funnel while continuously stirring for 1h to ensure homogeneity. 10mL of deionized water and 20mL of anhydrous ethanol were mixed, and 0.5mL of 1mol / L dilute nitric acid was added and mixed well to prepare the catalyst solution. While stirring vigorously, the catalyst solution was added dropwise to the dispersion at a very slow rate (1-2 drops / second) using a dropping funnel. After the addition was complete, stirring was continued at room temperature for 24h. After the reaction was completed, the product was collected by filtration, washed three times with anhydrous ethanol, and dried in a vacuum drying oven at 80℃ for 12h to obtain amorphous TiO2-modified single-walled carbon nanotubes.
[0065] S5. Under a nitrogen atmosphere, amorphous TiO2-modified single-walled carbon nanotubes (concentration 0.5wt%) were added to molten copper and ultrasonically stirred for 30 min to mix them evenly. The molten copper was rapidly solidified and hot-drawn into copper rods using a hot casting method. The mold exit temperature was controlled at 1100℃, the casting speed was 15mm / min, and the cooling distance was 50mm to obtain a single-walled carbon nanotube-copper composite material.
[0066] Comparative Example 4: A method for preparing a single-walled carbon nanotube-copper composite material, differing from Example 1 in that it does not involve cobalt nanoparticle treatment, titanium oxide treatment, or magnetic field treatment, and includes the following steps:
[0067] S1. Preparation of crude single-walled carbon nanotubes using a flotation catalytic method: Using n-hexane as the carbon source, a mixed solution of n-hexane, ferrocene (catalyst), and thiophene was catalytically cracked in a vertical furnace under a nitrogen atmosphere. The cracking temperature was 1100℃, the concentration of ferrocene was 0.50 g / 100 mL, the concentration of thiophene was 0.42 mL / 100 mL, the cracking time was 1 h, and nitrogen gas was purged for cooling after the reaction was completed.
[0068] S2. Take 80g of the above crude single-walled carbon nanotubes, add 0.5L of a mixed solution of hydrogen peroxide and dilute hydrochloric acid, with a volume ratio of 1:1 and a concentration of 2mol / L. React at 60℃ for 1h, filter, wash the filter residue three times with deionized water, and perform vacuum sintering. The vacuum degree is controlled at 90Pa and the temperature is controlled at 1800℃. After heat treatment for 4h, vacuum cool.
[0069] S3. Gradient oxidation of carbon nanotubes in mixed acid: 50g of purified single-walled carbon nanotubes were added to a three-necked flask containing 0.5L of a mixture of concentrated nitric acid and concentrated sulfuric acid. The mixture was stirred and mixed thoroughly. The volume ratio of concentrated sulfuric acid to concentrated nitric acid was 3:1, the concentration of concentrated nitric acid was 68%, and the concentration of concentrated sulfuric acid was 95%. The flask was placed in an oil bath at 40℃ and sonicated for 30min. The temperature was then lowered to 20℃ and sonicated for another 30min. After the reaction was completed, the precipitate was collected by vacuum filtration and washed with deionized water until the filtrate was neutral. The product was then dried in a vacuum drying oven at 60℃ for 12 hours to obtain gradient oxidized carbon nanotubes.
[0070] S4. Under a nitrogen atmosphere, gradient oxidized carbon nanotubes (concentration of 0.5wt%) are added to molten copper and ultrasonically stirred for 30 minutes to mix them evenly. The molten copper is rapidly solidified and hot-drawn into copper rods using a hot continuous casting method. The mold exit temperature is controlled at 1100℃, the casting speed is 15mm / min, and the cooling distance is 50mm to obtain a single-walled carbon nanotube-copper composite material.
[0071] The following tests were performed on the single-walled carbon nanotube-copper matrix composites prepared in Examples 1, 2, and Comparative Examples 1-4:
[0072] (1) SEM scanning detection
[0073] The single-walled carbon nanotube-copper composite materials prepared in Example 1 and Comparative Example 1 were subjected to SEM scanning detection, and the detection results are as follows: Figure 2 and Figure 3 As shown, where Figure 2 This is a SEM scan image of the carbon nanotube-copper composite material prepared in Example 1. Figure 3 The image shows the SEM scan results of the carbon nanotube-copper composite material prepared in Comparative Example 1.
[0074] As can be seen from the figure, in the carbon nanotube-copper composite material prepared in Example 1, the carbon nanotubes are arranged in an orderly manner and have a clear uniform orientation, indicating that they are oriented. However, in the carbon nanotube-copper composite material prepared in Comparative Example 1, because no magnetic field orientation treatment was performed during the preparation process, the single-walled carbon nanotubes in the composite material are randomly dispersed and do not have a clear uniform orientation or oriented arrangement.
[0075] (2) Conductivity test
[0076] The conductivity of the composite materials of Examples 1, 2, and Comparative Examples 1-4 was measured using a conductivity meter and the four-probe method at 25°C and 40% relative humidity. The samples were cut into uniform lengths, and the average value was calculated after three tests. The test results are shown in Table 1.
[0077] Table 1 Conductivity Test Results
[0078]
[0079] The data above show that the conductivity of the composite materials prepared in Examples 1 and 2 is around 110% IACS, which is an improvement in conductivity, indicating that the composite materials prepared in Examples 1 and 2 have high conductivity.
[0080] The test data shows that the method for preparing single-walled carbon nanotube-copper composite materials used in this patent can produce single-walled carbon nanotube-copper composite materials with good conductivity. The carbon nanotubes significantly affect the conductivity of the copper matrix through the electron tunneling effect. In contrast, the composite material in Comparative Example 1, without magnetic field orientation treatment of the single-walled carbon nanotubes, failed to achieve directional alignment within the copper matrix, affecting its conductivity and preventing the carbon nanotubes from significantly improving the conductivity of copper. The composite material in Comparative Example 2, without titanium oxide treatment, resulted in the single-walled carbon nanotubes and... Insufficient wettability between copper substrates affects the effective dispersion of single-walled carbon nanotubes, thus impacting the conductivity of the composite material. The conductivity of Comparative Example 3 is significantly lower than that of Comparative Example 1 because Comparative Example 3 did not undergo cobalt nanoparticle treatment, which affected the subsequent coating of titanium oxide and the formation of titanium carbide. The reaction temperature for generating a uniform titanium carbide layer from titanium oxide is at least 1400℃. If the temperature is too low, the formation of titanium carbide will be insufficient, or the reaction will be uneven, leading to an excessive reaction between some titanium oxide and carbon, which will destroy the structural integrity of the single-walled carbon nanotubes and thus affect the conductivity.
[0081] (3) Thermal conductivity test
[0082] The thermal conductivity of the single-walled carbon nanotube-copper composite materials prepared in Examples 1, 2, and Comparative Examples 1-4 was tested using GB / T 3651-2008 "Method for Measurement of Thermal Conductivity of Metals at High Temperature". The measurement results are shown in Table 2.
[0083] Table 2 Thermal conductivity test results
[0084]
[0085] As can be seen from Table 2, the thermal conductivity of the carbon nanotube-copper composite materials in Examples 1 and 2 is higher than that in Comparative Examples 1 to 4, indicating that the composite materials prepared using the method of this patent have significantly improved thermal conductivity.
[0086] (4) Mechanical tensile property test
[0087] The mechanical tensile properties of the carbon nanotube-copper composite materials prepared in Examples 1, 2, and Comparative Examples 1-4 were tested. The ultimate tensile strength was detected using a force sensor. Three parallel tests were performed, and the results were averaged. The test results are shown in Table 3.
[0088] Table 3 Ultimate Tensile Strength Test Results
[0089]
[0090] As can be seen from Table 3, the ultimate tensile strength of the carbon nanotube-copper composite materials in Examples 1 and 2 is higher than that of all comparative examples, indicating that the carbon nanotube-oriented composite materials prepared using the method of this patent have better mechanical properties.
[0091] Single-walled carbon nanotubes (SUVs) possess high electrical and thermal conductivity and high strength in their axial direction, but their radial properties are weaker. Unoriented SUVs in a copper matrix exhibit random distribution, potentially disrupting the continuity of the copper lattice and increasing electron scattering interfaces. This not only fails to improve the conductivity of the copper matrix but may even negatively impact its electrical and thermal conductivity. Conversely, oriented SUVs within the copper matrix form a continuous network, providing superconducting channels and creating a conductive and thermally conductive network that penetrates the entire copper matrix, significantly enhancing its electrical and thermal conductivity. SUVs also possess strong tensile strength. When oriented within the copper matrix, these oriented SUVs can directly absorb most of the force when pulled along their axial direction, reducing the burden on the copper matrix and resulting in improved macroscopic tensile strength.
[0092] The wettability between single-walled carbon nanotubes (SUVs) and copper substrates is insufficient. Therefore, when combining SUVs with copper substrates, the compatibility between the two is often poor. Traditional methods of mixing SUVs and copper result in weak bonding due to poor wettability. This invention anchors cobalt nanoparticles within SUVs and then coats amorphous titanium dioxide using a sol-gel method. Under high temperature and catalysis by cobalt nanoparticles, titanium dioxide reacts with carbon to form a dense titanium carbide layer, bridging the gap between SUVs and copper and achieving a good bond between them.
[0093] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.
Claims
1. A method for preparing a single-walled carbon nanotube-copper composite material, characterized in that, Includes the following steps: S1. Single-walled carbon nanotubes were prepared using a flotation catalysis method, and the single-walled carbon nanotubes were then subjected to acid washing and high-temperature purification. S2. Under a nitrogen atmosphere, amorphous TiO2 composite cobalt nanoparticles modified with single-walled carbon nanotubes were added to molten copper and ultrasonically stirred for 0.5-1 h. After mixing, magnetic field-assisted stirring was performed with the stirring direction parallel to the magnetic field direction. The temperature of the molten copper was reduced to 1100-1150℃ and stirred for 30 min. S3. Use hot casting to rapidly solidify molten copper and heat-draw it into a copper rod. During this process, continue to use magnetic field assistance. The direction of the magnetic field is parallel to the stirring direction of molten copper in the melt system and the flow direction of molten copper in the mold heating system. The mold heating system continuously casts the copper rod along the direction of the magnetic field to obtain a single-walled carbon nanotube-copper composite material. The method for preparing the amorphous TiO2 composite cobalt nanoparticle-modified single-walled carbon nanotubes is as follows: the cobalt nanoparticle-modified single-walled carbon nanotubes are dispersed in anhydrous ethanol, sonicated for 30 min, and tetrabutyl titanate is slowly added dropwise while stirring for 0.5-1 h; under vigorous stirring, a catalyst solution is slowly added dropwise while stirring at room temperature for 12-24 h; the product is collected by filtration, washed three times with anhydrous ethanol, and vacuum dried at 60-80℃ for 12 h to obtain the product. The method for preparing the cobalt nanoparticle-modified single-walled carbon nanotubes is as follows: Gradient oxidized carbon nanotubes are dispersed in deionized water and sonicated for 0.5-1 h. Under a nitrogen atmosphere, CoCl2 solution is added and stirred for 30 min, and the pH is adjusted to 9-10. Under vigorous stirring, NaBH4 solution is added dropwise, and the reaction continues for 2 h. After the reaction is completed, the product is separated by precipitation with a magnet, washed three times with anhydrous ethanol, and vacuum dried at 60℃ for 12 h to obtain the final product. The method for preparing gradient oxidized carbon nanotubes is as follows: prepare a mixed acid solution containing concentrated sulfuric acid and concentrated nitric acid, with a volume ratio of concentrated sulfuric acid to concentrated nitric acid of 3:1; add the purified single-walled carbon nanotubes to the mixed acid solution; sonicate at 40°C for 30 min; cool to 20°C and sonicate for 30 min; filter; collect the precipitate; wash with deionized water until neutral; and vacuum dry to obtain the final product.
2. The method for preparing a single-walled carbon nanotube-copper composite material according to claim 1, characterized in that, In step S1, the acid washing and high-temperature repair and purification steps are as follows: the single-walled carbon nanotubes are acid washed and purified with a mixed solution of hydrogen peroxide and dilute hydrochloric acid. After reacting at 60°C for 1 hour, they are washed with deionized water to obtain crude single-walled carbon nanotubes. The volume ratio of hydrogen peroxide to dilute hydrochloric acid is 1:
1. The crude single-walled carbon nanotubes are heat-treated at 1800°C below 90 Pa in a vacuum sintering furnace for 4 hours, and then cooled under vacuum to obtain purified single-walled carbon nanotubes.
3. The method for preparing a single-walled carbon nanotube-copper composite material according to claim 1, characterized in that, The mass ratio of the cobalt nanoparticle-modified single-walled carbon nanotubes to tetrabutyl titanate is 1:1.5~3; the catalyst solution is prepared by mixing deionized water and anhydrous ethanol, adding dilute nitric acid dropwise, and mixing well to obtain the catalyst solution; wherein the mass ratio of deionized water, anhydrous ethanol and dilute nitric acid is 1:2:0.05; the catalyst solution is slowly added at a rate of 1~2 drops / second.
4. The method for preparing a single-walled carbon nanotube-copper composite material according to claim 1, characterized in that, The mass ratio of gradient oxidized carbon nanotubes to deionized water is 1:20, the concentration of CoCl2 solution is 0.1 mol / L, the concentration of NaBH4 solution is 0.2 mol / L, and the volume ratio of CoCl2 solution, NaBH4 solution to deionized water is 2:1:
4.
5. The method for preparing a single-walled carbon nanotube-copper composite material according to claim 1, characterized in that, In steps S2 and S3, the magnetic field-assisted method is as follows: an electromagnetic coil is wound around the outside of the melt system and the mold heating system to add a directional magnetic field, with the magnetic field direction, stirring direction and molten copper flow direction in the mold heating system being parallel.
6. The method for preparing a single-walled carbon nanotube-copper composite material according to claim 5, characterized in that, The external magnetic field strength of the melt system is 0.5~1T, and the external magnetic field strength of the casting heating system is 1~2T.
7. The method for preparing a single-walled carbon nanotube-copper composite material according to claim 1, characterized in that, In step S3, the process parameters of the hot continuous casting method are: the temperature of the melt system is 1100~1150℃, the temperature at the mold outlet is 1100~1150℃, and the casting speed is 10~15mm / min.