A method for preparing a carbon nanotube porous high thermal conductivity interlayer suitable for brazing
By loading a carbon source with a hydrothermal method and annealing it on the surface of copper foam to generate carbon nanotubes, the problem of uneven growth of carbon nanotubes on the intermediate layer of copper foam was solved. This resulted in a porous, high thermal conductivity intermediate layer of carbon nanotubes with high adhesion and high thermal conductivity, which is suitable for brazing joint materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HARBIN INST OF TECH
- Filing Date
- 2025-01-07
- Publication Date
- 2026-07-03
AI Technical Summary
The growth of carbon nanotubes on the existing foamed copper interlayer suffers from problems such as excessive or uneven distribution of catalyst, resulting in poor adhesion and low thermal conductivity of carbon nanotubes.
Carbon nanotubes were generated on the surface of copper foam by loading a carbon source using a hydrothermal method and annealing at 550℃~750℃. The catalytic effect of the copper foam substrate itself was utilized, avoiding the use of precious metal catalysts. By controlling parameters such as glucose solution concentration, reaction time and temperature, uniform growth and high adhesion of carbon nanotubes were achieved.
It improves the adhesion and thermal conductivity of carbon nanotubes, simplifies the process, reduces costs, and minimizes metal residue pollution. It is suitable for complex structures and heat-sensitive substrates, and is environmentally friendly and safe, making it suitable for mass production.
Smart Images
Figure CN119750557B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing a brazing intermediate layer. Background Technology
[0002] Growing carbon nanotubes (CNTs) on copper foam interlayers is of significant research and application value. The aim is to leverage the excellent thermal, electrical, and mechanical properties of CNTs to further improve the overall performance of copper foam, thereby meeting the demands for high-performance brazing joint materials. Copper foam, as a metallic material with high porosity and excellent thermal conductivity, is often used as a brazing interlayer to achieve efficient connections between different materials. However, in practical applications, copper foam may face problems such as insufficient thermal conductivity and unstable mechanical properties, which limits its widespread application in fields requiring high thermal conductivity and precision joining.
[0003] By growing uniformly distributed carbon nanotube arrays on the surface of copper foam, the thermal conductivity and interfacial bonding strength of copper foam can be further enhanced, improving its performance in brazing applications. Currently, chemical vapor deposition (CVD), laser discharge, and arc discharge methods are widely used to prepare carbon nanotube arrays, but these processes are complex and costly. During the use of catalysts to promote carbon nanotube growth, the growth quality is often significantly affected by the dispersion, size, and morphology of the catalyst. Therefore, selecting and optimizing the catalyst is crucial for achieving high-quality, uniformly distributed carbon nanotube arrays. When growing carbon nanotubes in copper foam, the bonding quality between the catalyst and the substrate directly determines the adhesion and growth efficiency of the carbon nanotubes, and also affects the thermal conductivity and mechanical properties of the composite material. Achieving good bonding between the catalyst and carbon nanotubes in the intermediate layer of copper foam can significantly improve the thermal conductivity, mechanical strength, and electrical properties of the brazed joint. However, existing research still faces problems such as uneven catalyst distribution and poor carbon nanotube adhesion, necessitating further optimization of the preparation process to achieve high performance and reliable application of copper foam-carbon nanotube composites. Summary of the Invention
[0004] The present invention aims to solve the problem that the growth of carbon nanotubes on the existing foamed copper interlayer has problems such as excessive or uneven distribution of catalyst, resulting in poor adhesion and low thermal conductivity of carbon nanotubes. Therefore, it provides a method for preparing a porous carbon nanotube high thermal conductivity interlayer suitable for brazing.
[0005] A method for preparing a porous, highly thermally conductive carbon nanotube interlayer suitable for brazing, comprising the following steps:
[0006] I. Using hydrothermal methods to load carbon sources:
[0007] ① Dissolve glucose in deionized water and stir until homogeneous at room temperature to obtain a glucose solution;
[0008] ②Immerse copper foam in glucose solution and react under high temperature and pressure;
[0009] ③ After the high temperature and high pressure reaction, the mixture is cooled to room temperature to obtain copper foam supported on a carbon source;
[0010] II. Annealing at high temperature:
[0011] Under a protective atmosphere and a temperature of 550℃~750℃, copper foam loaded with carbon source is kept at a temperature of 4h~5h, and finally cooled in the furnace and taken out to obtain a porous high thermal conductivity carbon nanotube intermediate layer. This completes the preparation method of a porous high thermal conductivity carbon nanotube intermediate layer suitable for brazing.
[0012] The beneficial effects of this invention are:
[0013] 1. Enhanced Adhesion and High Thermal Conductivity: A hydrothermal glucose solution method is used to coat the surface of copper foam with a product, followed by high-temperature annealing to generate dense carbon nanotubes. The main reason for this growth is that after the hydrothermal reaction, a uniform carbon layer is coated onto the surface of the copper foam, while Cu diffuses from the substrate material to the surface, transferring to the carbon layer in the form of copper nanospheres. These uniformly distributed copper nanospheres form a densely arranged catalytic array, acting as a catalyst for carbon nanotube growth and ensuring uniform growth. Under the catalytic action of the Cu nanospheres, the carbon nanotubes recrystallize and grow into structurally regular carbon nanotubes. This spontaneous in-situ growth via the copper foam substrate results in stronger adhesion, and the prepared porous, high-thermal-conductivity intermediate layer of carbon nanotubes exhibits excellent thermal conductivity, reaching 28 W / m·K.
[0014] 2. No additional catalyst required: Traditional methods usually rely on precious metal catalysts (such as iron, cobalt, and nickel) to promote the growth of carbon nanotubes. However, this method utilizes the catalytic effect of the foamed copper substrate itself to generate carbon nanotubes through the annealing process. This avoids the catalyst preparation and deposition steps, simplifies the process, reduces costs, and reduces the pollution problems that may be caused by metal residues.
[0015] 3. Lower Temperature Requirement: This method first forms a uniform carbon precursor on the substrate through a hydrothermal reaction, and then carbon nanotubes can be grown by annealing at a relatively low temperature of 550℃ to 750℃. In contrast, traditional methods such as chemical vapor deposition (CVD) typically require a high-temperature environment of 800℃ to 1000℃. The lower annealing temperature not only saves energy but also reduces the risk of deformation, oxidation, or damage to the substrate material due to high temperatures. It is particularly suitable for processing heat-sensitive or complex substrates, such as copper foam.
[0016] 4. Simple and controllable process: The hydrothermal method offers mild conditions and simple operation. By adjusting parameters such as glucose solution concentration, reaction time, and temperature, the morphology and distribution of the carbon precursor can be precisely controlled, thereby achieving high coverage and uniform distribution of carbon nanotubes on the substrate surface. This high controllability helps optimize the structure and properties of carbon nanotubes, improving the quality and consistency of the final product.
[0017] 5. Suitable for complex geometries: The surface of copper foam has a three-dimensional porous network structure. Traditional vapor deposition methods tend to form non-uniform coatings on complex geometries, while the hydrothermal method, through liquid-phase reaction, allows the glucose solution to fully wet the substrate surface and pores, ensuring uniform deposition of the carbon precursor. During subsequent annealing, carbon nanotubes can also form a uniform growth distribution throughout the entire network structure.
[0018] 6. No byproduct pollution: The hydrothermal method uses glucose as a carbon source, which is non-toxic and harmless, and produces almost no harmful gases or byproducts during the reaction. Compared with traditional carbon nanotube growth methods (such as those using gaseous carbon sources such as methane and acetylene, which may release toxic byproducts), this process is more environmentally friendly and safer.
[0019] 7. Suitable for batch production and industrialization: The hydrothermal reaction has good scalability, allowing for the simultaneous processing of multiple samples. Combined with low-temperature annealing, this method offers high economic efficiency and operability in batch production, making it more suitable for industrial applications. With its advantages of being environmentally friendly, low-cost, highly efficient, and easy to operate, this process provides an innovative and practical technical route for the growth of carbon nanotubes on copper foam surfaces, and is particularly suitable for the preparation of composite materials in the fields of thermal conductivity, heat dissipation, and energy. Attached Figure Description
[0020] Figure 1 This is a scanning electron microscope image of the porous, highly thermally conductive carbon nanotube intermediate layer prepared in Example 1;
[0021] Figure 2 This is a transmission electron microscopy (TEM) energy dispersive spectroscopy (EDS) image of the copper nanosphere catalytic array in the porous, highly thermally conductive intermediate layer of carbon nanotubes prepared in Example 1.
[0022] Figure 3 A digital photograph of the porous, highly thermally conductive carbon nanotube intermediate layer prepared in Example 1;
[0023] Figure 4 The image shows the enhanced Raman curve of the porous, highly thermally conductive intermediate layer of carbon nanotubes prepared in Example 1. Detailed Implementation
[0024] Specific Implementation Method 1: This implementation method provides a method for preparing a porous, highly thermally conductive interlayer of carbon nanotubes suitable for brazing, which is carried out according to the following steps:
[0025] I. Using hydrothermal methods to load carbon sources:
[0026] ① Dissolve glucose in deionized water and stir until homogeneous at room temperature to obtain a glucose solution;
[0027] ②Immerse copper foam in glucose solution and react under high temperature and pressure;
[0028] ③ After the high temperature and high pressure reaction, the mixture is cooled to room temperature to obtain copper foam supported on a carbon source;
[0029] II. Annealing at high temperature:
[0030] Under a protective atmosphere and a temperature of 550℃~750℃, copper foam loaded with carbon source is kept at a temperature of 4h~5h, and finally cooled in the furnace and taken out to obtain a porous high thermal conductivity carbon nanotube intermediate layer. This completes the preparation method of a porous high thermal conductivity carbon nanotube intermediate layer suitable for brazing.
[0031] The beneficial effects of this embodiment are:
[0032] 1. Enhanced Adhesion and High Thermal Conductivity: A hydrothermal glucose solution method is used to coat the surface of copper foam with a product, followed by high-temperature annealing to generate dense carbon nanotubes. The main reason for this growth is that after the hydrothermal reaction, a uniform carbon layer is coated onto the surface of the copper foam, while Cu diffuses from the substrate material to the surface, transferring to the carbon layer in the form of copper nanospheres. These uniformly distributed copper nanospheres form a densely arranged catalytic array, acting as a catalyst for carbon nanotube growth and ensuring uniform growth. Under the catalytic action of the Cu nanospheres, the carbon nanotubes recrystallize and grow into structurally regular carbon nanotubes. This spontaneous in-situ growth via the copper foam substrate results in stronger adhesion, and the prepared porous, high-thermal-conductivity intermediate layer of carbon nanotubes exhibits excellent thermal conductivity, reaching 28 W / m·K.
[0033] 2. No additional catalyst required: Traditional methods usually rely on precious metal catalysts (such as iron, cobalt, and nickel) to promote the growth of carbon nanotubes. However, this method utilizes the catalytic effect of the foamed copper substrate itself to generate carbon nanotubes through the annealing process. This avoids the catalyst preparation and deposition steps, simplifies the process, reduces costs, and reduces the pollution problems that may be caused by metal residues.
[0034] 3. Lower Temperature Requirement: This method first forms a uniform carbon precursor on the substrate through a hydrothermal reaction, and then carbon nanotubes can be grown by annealing at a relatively low temperature of 550℃ to 750℃. In contrast, traditional methods such as chemical vapor deposition (CVD) typically require a high-temperature environment of 800℃ to 1000℃. The lower annealing temperature not only saves energy but also reduces the risk of deformation, oxidation, or damage to the substrate material due to high temperatures. It is particularly suitable for processing heat-sensitive or complex substrates, such as copper foam.
[0035] 4. Simple and controllable process: The hydrothermal method offers mild conditions and simple operation. By adjusting parameters such as glucose solution concentration, reaction time, and temperature, the morphology and distribution of the carbon precursor can be precisely controlled, thereby achieving high coverage and uniform distribution of carbon nanotubes on the substrate surface. This high controllability helps optimize the structure and properties of carbon nanotubes, improving the quality and consistency of the final product.
[0036] 5. Suitable for complex geometries: The surface of copper foam has a three-dimensional porous network structure. Traditional vapor deposition methods tend to form non-uniform coatings on complex geometries, while the hydrothermal method, through liquid-phase reaction, allows the glucose solution to fully wet the substrate surface and pores, ensuring uniform deposition of the carbon precursor. During subsequent annealing, carbon nanotubes can also form a uniform growth distribution throughout the entire network structure.
[0037] 6. No byproduct pollution: The hydrothermal method uses glucose as a carbon source, which is non-toxic and harmless, and produces almost no harmful gases or byproducts during the reaction. Compared with traditional carbon nanotube growth methods (such as those using gaseous carbon sources such as methane and acetylene, which may release toxic byproducts), this process is more environmentally friendly and safer.
[0038] 7. Suitable for batch production and industrialization: The hydrothermal reaction has good scalability, allowing for the simultaneous processing of multiple samples. Combined with low-temperature annealing, this method offers high economic efficiency and operability in batch production, making it more suitable for industrial applications. With its advantages of being environmentally friendly, low-cost, highly efficient, and easy to operate, this process provides an innovative and practical technical route for the growth of carbon nanotubes on copper foam surfaces, and is particularly suitable for the preparation of composite materials in the fields of thermal conductivity, heat dissipation, and energy.
[0039] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the concentration of the glucose solution mentioned in step one ① is 0.1 mol / L to 1 mol / L. Everything else is the same as in Specific Implementation Method One.
[0040] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the copper foam described in step one, ②, has a porosity (PPI) of 90-100 per inch. Everything else is the same as in Specific Implementation Method One or Two.
[0041] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the high-temperature and high-pressure reaction described in step one, ②, is specifically carried out at a reaction temperature of 180℃~200℃ and a pressure of 5MPa~10MPa for 3h~6h. Everything else is the same as in Specific Implementation Method Three.
[0042] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the high-temperature and high-pressure reaction described in step one, step two, is specifically carried out at a reaction temperature of 180℃~200℃ and a pressure of 5MPa~10MPa for 6 hours. Everything else is the same as in Specific Implementation Methods One to Four.
[0043] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the protective atmosphere described in step two is one or a mixture of several of argon, hydrogen, and nitrogen. Everything else is the same as in Specific Implementation Methods One to Five.
[0044] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the gas flow rate of the protective atmosphere mentioned in step two is 50 sccm to 80 sccm. Everything else is the same as in Specific Implementation Methods One to Six.
[0045] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that, in step two, under a protective atmosphere, the carbon-source-loaded copper foam is heated to 550°C to 750°C at a heating rate of 5°C / min to 15°C / min. Everything else is the same as in Specific Implementation Methods One to Seven.
[0046] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that, in step two, under a protective atmosphere, the carbon-source-loaded copper foam is heated to 600°C to 750°C at a heating rate of 5°C / min to 10°C / min. Everything else is the same as in Specific Implementation Methods One to Eight.
[0047] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that: in step two, the copper foam loaded with the carbon source is kept at a protective atmosphere and a temperature of 600℃~750℃ for 4h~5h. Everything else is the same as in Specific Implementation Methods One to Nine.
[0048] The beneficial effects of the present invention are verified using the following embodiments:
[0049] Example 1:
[0050] A method for preparing a porous, highly thermally conductive carbon nanotube interlayer suitable for brazing, comprising the following steps:
[0051] I. Using hydrothermal methods to load carbon sources:
[0052] ① Dissolve glucose in deionized water and stir until homogeneous at room temperature to obtain a glucose solution;
[0053] The concentration of the glucose solution is 0.1 mol / L;
[0054] ②The copper foam was immersed in a glucose solution and reacted under high temperature and high pressure for 6 hours at a reaction temperature of 180℃ and a pressure of 5MPa.
[0055] The copper foam has a porosity of 95 PPI and a diameter of 25 mm.
[0056] ③ After the high temperature and high pressure reaction, the mixture is cooled to room temperature to obtain copper foam supported on a carbon source;
[0057] II. Annealing at high temperature:
[0058] Under a protective atmosphere and a gas flow rate of 50 sccm, the temperature was raised to 550℃ at a heating rate of 5℃ / min. Then, under a protective atmosphere, a gas flow rate of 50 sccm, and a temperature of 550℃, the carbon source-loaded copper foam was kept at this temperature for 4 hours. Finally, it was cooled in the furnace and removed to obtain a porous high thermal conductivity carbon nanotube intermediate layer.
[0059] The protective atmosphere is argon.
[0060] Figure 1 The image shows a scanning electron microscope (SEM) image of the porous, highly thermally conductive carbon nanotube intermediate layer prepared in Example 1. As can be seen from the image, the carbon nanotubes are densely distributed on the copper foam framework, and there are granular spheres, i.e., Cu nanospheres, at the root of the carbon nanotubes.
[0061] Figure 2 This is a transmission electron microscopy (TEM) energy dispersive spectroscopy (EDS) image of the copper nanosphere catalytic array in the porous, highly thermally conductive intermediate layer of carbon nanotubes prepared in Example 1. Hydrothermal carbon decomposes into a gaseous carbon source upon heating, which is then vertically dropped and deposited in situ. EDS indicates that Cu diffuses from the substrate material to the surface, and the Cu nanospheres are uniformly distributed, thus using Cu nanospheres as a catalyst for carbon nanotube growth.
[0062] Figure 3 This is a digital photograph of the porous, highly thermally conductive carbon nanotube intermediate layer prepared in Example 1. Because carbon has a strong absorption of photons, this example appears distinctly black, adheres well to the substrate, and is evenly distributed.
[0063] Figure 4 The image shows the enhanced Raman curve of the porous, highly thermally conductive carbon nanotube intermediate layer prepared in Example 1. As can be seen from the image, the carbon peak is obvious, exhibiting an I peak due to the influence of hydrothermal carbon retained on the substrate. D >I G trend.
[0064] The thermal conductivity of the porous high thermal conductivity intermediate layer of carbon nanotubes prepared in Example 1 reached 28 W / m·K, while the thermal conductivity of the original copper foam was only 13 W / m·K, which is more than double.
Claims
1. A method for preparing a porous, highly thermally conductive interlayer of carbon nanotubes suitable for brazing, characterized in that... It is done in the following steps: I. Using hydrothermal methods to load carbon sources: ① Dissolve glucose in deionized water and stir until homogeneous at room temperature to obtain a glucose solution; The concentration of the glucose solution is 0.1 mol / L; ②The copper foam was immersed in a glucose solution and reacted under high temperature and high pressure for 6 hours at a reaction temperature of 180℃ and a pressure of 5MPa. The copper foam has a porosity of 95 PPI and a diameter of 25 mm. ③ After the high temperature and high pressure reaction, the mixture is cooled to room temperature to obtain copper foam supported on a carbon source; II. Annealing at high temperature: Under a protective atmosphere and a gas flow rate of 50 sccm, the temperature was raised to 550℃ at a heating rate of 5℃ / min. Then, under a protective atmosphere, a gas flow rate of 50 sccm, and a temperature of 550℃, the carbon source-loaded copper foam was kept at this temperature for 4 hours. Finally, it was cooled in the furnace and removed to obtain a porous high thermal conductivity carbon nanotube intermediate layer. The protective atmosphere is argon. In the aforementioned porous, highly thermally conductive carbon nanotube intermediate layer, carbon nanotubes are densely distributed on a copper foam framework, and Cu nanospheres are present at the root of the carbon nanotubes. The thermal conductivity of the porous, highly thermally conductive carbon nanotube intermediate layer is 28 W / m·K.