Preparation method of composite insulation heat dissipation structure based on sequential carbon nano deposition

Abstract

The invention relates to the field of composite insulation heat dissipation materials, in particular to a preparation method of a composite insulation heat dissipation structure based on sequential carbon nano-deposition, which specifically comprises the following steps: a copper wire continuously passes through a liquid phase deposition area at a stable speed, and the copper wire is deposited in a liquid phase deposition area under the auxiliary action of an alternating electromagnetic field; the functionalized graphene is gradually deposited and self-assembled to form a compact insulating bottom layer; continuously depositing for 5-30 minutes, so that the carbon source is cracked under the action of the catalyst and epitaxially grows on the graphene bottom layer to form a vertical orientation carbon nanostructure enhancement layer; in the last 1-3 minutes of the deposition process, introducing water vapor or carbon dioxide gas, carrying out mild oxidation treatment on the surface of the carbon nanostructure, etching part of amorphous carbon and opening a pipe orifice to construct a micropore-mesopore composite porous surface structure; the copper wire is placed in an inert atmosphere or a reducing atmosphere for high-temperature annealing treatment, the copper wire with the composite insulation heat dissipation structure is obtained, and the technical problem that insulation and heat dissipation of a traditional material at the present stage are difficult to achieve at the same time is solved.

Description

[0001] This invention relates to the field of composite insulating and heat dissipation materials, and specifically to a method for preparing a composite insulating and heat dissipation structure based on sequential carbon nanotube deposition. Background Technology

[0002] With the rapid development of modern technology, the application scenarios of wires and cables are becoming increasingly widespread, covering multiple cutting-edge fields such as aerospace, high-end manufacturing, new energy, intelligent transportation, and motor and electrical control. The performance requirements for these cables are also increasing. As the core carrier for power transmission and signal transmission, the insulation safety and thermal management capabilities of copper wire during operation directly determine the stability, reliability, and service life of the entire electrical system. However, traditional organic insulating materials such as polyimide varnish, while possessing good film-forming properties and a certain dielectric strength, are prone to aging and have low thermal conductivity at high temperatures, leading to heat accumulation and affecting system efficiency and safety. On the other hand, although a single graphene coating is considered an ideal heat dissipation material due to its excellent thermal conductivity, its high conductivity and low breakdown strength make it difficult to meet the insulation requirements under high-voltage environments, posing a risk of breakdown and short circuit. Therefore, how to significantly improve the heat dissipation capacity of copper wire without sacrificing electrical insulation performance, achieving integrated synergistic optimization of "high insulation-high heat dissipation," has become a key scientific problem and technical bottleneck that urgently needs to be overcome in the field of electronic materials and cable technology. This paper proposes a method for preparing a composite insulating and heat dissipation structure based on sequential carbon nanotube deposition to solve the above problems. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing a composite insulating and heat-dissipating structure based on sequential carbon nanotube deposition, which solves the technical problem that traditional materials cannot achieve both insulation and heat dissipation at the present stage.

[0004] The objective of this invention can be achieved through the following technical solutions: A method for preparing a composite insulating and heat-dissipating structure based on sequential carbon nanotube deposition, specifically including the following steps: Step S1: Copper wires pass through the liquid phase deposition zone at a stable speed. Under the assistance of an alternating electromagnetic field, functionalized graphene is gradually deposited and self-assembled to form a dense insulating underlayer. This bottom layer not only has excellent electrical insulation properties, but also effectively blocks the impact of subsequent high-temperature processes on the copper substrate, while providing a structurally stable and firmly bonded basic interface for the growth of the intermediate layer. Step S2: Continue deposition for 5-30 minutes to allow the carbon source to decompose under the action of the catalyst and grow epitaxially on the graphene substrate, forming a 3-15 μm thick vertically oriented carbon nanostructure reinforcement layer. This layer has extremely high axial thermal conductivity, which significantly improves the in-plane thermal conductivity of the material. The measured thermal conductivity can reach 20-180 W / (m·K), thereby constructing an efficient longitudinal heat conduction channel and greatly enhancing the overall heat dissipation efficiency of the copper wire. Step S3: In the last 1-3 minutes of the deposition process, a trace amount of water vapor or carbon dioxide gas is introduced to perform a controlled and mild oxidation treatment on the surface of the carbon nanostructure, etching part of the amorphous carbon and opening the tube opening to construct a porous surface structure of micropore-mesopore composite. This structure not only significantly increases the specific surface area, but also facilitates subsequent encapsulation or coating adhesion, and improves the material's environmental adaptability and chemical stability; Step S4: Subsequently, the copper wire is placed in an inert atmosphere (argon) or a reducing atmosphere (ammonia) and subjected to high-temperature annealing at 300-1100℃ for 15-60 minutes to obtain a copper wire with a composite insulation and heat dissipation structure. Step S4 is used to eliminate lattice defects and residual stress generated during the deposition process, and to promote interfacial diffusion and bonding between layers, thereby further enhancing the mechanical strength, thermal stability and long-term service reliability of the overall structure.

[0005] Furthermore, in step S1, the concentration of the functionalized graphene dispersion in the liquid phase deposition is 1-10 mg / mL, and an alternating electromagnetic field parallel to the wire axis is applied with a frequency range of 50-10 kHz and an intensity of 0.1-0.8 T to obtain a dense insulating underlayer with a thickness of 0.5-3 μm. The mechanism of this electromagnetic field is to induce the graphene sheets to generate dipole moments, causing them to tend to align perpendicular to the copper wire surface during the deposition process, thereby improving the density, uniformity and interlayer stacking quality of the underlying layer.

[0006] Furthermore, the solvent for the functionalized graphene dispersion in step S1 is specifically deionized water or N-methylpyrrolidone (NMP), wherein the functionalized graphene is specifically carboxylated graphene, hydroxylated graphene, etc. The oxygen-containing functional groups on the surface help improve its dispersion stability in solvents and enhance its interfacial bonding with the copper matrix.

[0007] Furthermore, in step S1, the copper wire passes through at a speed of 0.2-2 m / min, and the breakdown strength of the dense insulating layer can reach 300-600 V / μm.

[0008] Furthermore, in step S2, high-purity argon is used as the carbon source, and methane or acetylene (volume concentration controlled at 5-20%) is fully mixed with ferrocene catalyst (vapor concentration maintained at 0.1-1.0%) to form a uniform and stable aerosol system. The selection of carbon source gas and its concentration ratio directly affect the nucleation density and growth rate of carbon nanostructures, which are key factors determining the final thermal conductivity.

[0009] Further, the deposition conditions in step S2 are as follows: in the high-temperature reaction chamber, the temperature is controlled at 700-900℃, the pressure inside the chamber is 1-10kPa, and an axial constant or gradient magnetic field of 0.05-0.3T is applied simultaneously. Excessive temperature may deactivate the catalyst, while excessively low temperature will slow down growth; the combined effect of pressure and magnetic field can regulate the orientation consistency and array density of carbon nanotubes (CNTs) or carbon nanofibers (CNFs).

[0010] The beneficial effects of this invention are as follows: By precisely controlling the process parameters at each stage of liquid-phase deposition, vapor-phase growth, and post-treatment, this invention successfully constructs a composite insulating and heat-dissipating coating with a gradient structure. This structure comprehensively outperforms traditional single-material coatings (such as polyimide varnish) or graphene coatings prepared using only a single deposition technique in terms of insulation performance, thermal management capability, mechanical adhesion, and flexibility. Particularly noteworthy is that all embodiments achieve the synergistic optimization goals of a breakdown voltage exceeding 3kV and a thermal resistance reduction rate of not less than 55%, and maintain structural integrity even after repeated bending tests, demonstrating excellent practical potential. Therefore, this invention effectively solves the long-standing problem of mutually exclusive "insulation-heat dissipation" performance in the field of wires and cables, providing a new technical path for the design and manufacturing of high-performance conductor materials. Detailed Implementation

[0011] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0012] Example 1: A method for preparing a composite insulating and heat-dissipating structure based on sequential carbon nanotube deposition, specifically including the following steps: Bare copper wire with a diameter of 0.5 mm was selected and passed through a deposition tank containing 2 mg / mL carboxylated graphene aqueous dispersion (with 0.1% nonionic dispersant) at a constant speed of 0.5 m / min. It was deposited for 3 minutes in an alternating magnetic field environment of 50 Hz and 0.3 T to form a dense graphene-based insulating underlayer with a thickness of about 1.2 μm. The dispersion formulation consists of carboxylated graphene (COOH content ~5 at%), at a concentration of 2.0 mg / mL, using deionized water as the solvent. 0.1 wt% Triton X-100 is added as a nonionic dispersant to improve dispersion stability. Process parameters: Copper wire travel speed 0.5 m / min. Axial alternating magnetic field applied, frequency 50 Hz, intensity 0.3 T. Deposition time 3 minutes.

[0013] The system was transferred to a chemical vapor deposition system. Under the conditions of 750℃ and 0.1T axial constant magnetic field, a mixed aerosol of 10% C2H2 + 0.5% ferrocene / Ar was introduced and deposited for 10 minutes to grow a vertically oriented carbon nanotube layer with a thickness of about 5.5μm. The gas source formulation includes: high-purity argon (Ar, 99.999% purity) as the carrier gas, and acetylene (C2H2) as the carbon source gas, with a volume concentration of 10%. The catalyst is ferrocene (Fe(Cp)2), and its vapor concentration is maintained at 0.5% using a temperature-controlled evaporator. Process parameters: reaction temperature 750℃, chamber pressure 5kPa. A constant axial magnetic field with an intensity of 0.1T is applied. Deposition time 10 minutes; After deposition, the structure is annealed for 30 minutes in a high-purity argon atmosphere at 600-800℃ to complete the densification and defect repair. Process parameters: Anneal at 700℃ for 30 minutes in a high-purity argon atmosphere.

[0014] Example 2: A method for preparing a composite insulating and heat-dissipating structure based on sequential carbon nanotube deposition, specifically including the following steps: Bare copper wire with a diameter of 0.5 mm was selected and passed through a deposition tank containing 5 mg / mL carboxylated graphene aqueous dispersion (with 0.1% nonionic dispersant) at a constant speed of 0.5 m / min. It was deposited for 5 minutes in an alternating magnetic field environment of 50 Hz and 0.5 T to form a dense graphene-based insulating underlayer with a thickness of about 2.8 μm. The dispersion formulation consists of carboxylated graphene (COOH content ~5 at%), at a concentration of 5.0 mg / mL, using deionized water as the solvent. 0.1 wt% Triton X-100 is added as a nonionic dispersant to improve dispersion stability. Process parameters: Copper wire travel speed 0.5 m / min. Axial alternating magnetic field applied, frequency 50 Hz, intensity 0.5 T. Deposition time 5 minutes.

[0015] The system was transferred to a chemical vapor deposition system. Under the conditions of 750℃ and 0.1T axial constant magnetic field, a mixed aerosol of 10% C2H2 + 0.5% ferrocene / Ar was introduced and deposited for 5 minutes to grow a vertically oriented carbon nanotube layer with a thickness of about 2.2μm. The gas source formulation includes: high-purity argon (Ar, 99.999% purity) as the carrier gas, and acetylene (C2H2) as the carbon source gas, with a volume concentration of 10%. The catalyst is ferrocene (Fe(Cp)2), and its vapor concentration is maintained at 0.5% using a temperature-controlled evaporator. Process parameters: reaction temperature 750℃, chamber pressure 5kPa. A constant axial magnetic field with an intensity of 0.1T is applied. Deposition time 5 minutes. After deposition, the structure is annealed for 30 minutes in a high-purity argon atmosphere at 600-800℃ to complete the densification and defect repair. Process parameters: Anneal at 700℃ for 30 minutes in a high-purity argon atmosphere.

[0016] Example 3: A method for preparing a composite insulating and heat dissipation structure based on sequential carbon nanotube deposition, specifically including the following steps: Bare copper wire with a diameter of 0.5 mm was selected and passed through a deposition tank containing 2 mg / mL carboxylated graphene aqueous dispersion (with 0.1% nonionic dispersant) at a constant speed of 0.5 m / min. It was deposited for 3 minutes in an alternating magnetic field environment of 50 Hz and 0.3 T to form a dense graphene-based insulating underlayer with a thickness of about 1.2 μm. The dispersion formulation consists of carboxylated graphene (COOH content ~5 at%), at a concentration of 2.0 mg / mL, using deionized water as the solvent. 0.1 wt% Triton X-100 is added as a nonionic dispersant to improve dispersion stability. Process parameters: Copper wire travel speed 0.5 m / min. Axial alternating magnetic field applied, frequency 50 Hz, intensity 0.3 T. Deposition time 3 minutes.

[0017] The system was transferred to a chemical vapor deposition system. Under the conditions of 750℃ and 0.15T axial constant magnetic field, a mixed aerosol of 15% C2H2 + 0.5% ferrocene / Ar was introduced and deposited for 15 minutes to grow a vertically oriented carbon nanotube layer with a thickness of about 2.2μm. The gas source formulation includes: high-purity argon (Ar, 99.999% purity) as the carrier gas, and acetylene (C2H2) as the carbon source gas, with a volume concentration of 15%. The catalyst is ferrocene (Fe(Cp)2), and its vapor concentration is maintained at 0.5% using a temperature-controlled evaporator. Process parameters: reaction temperature 750℃, chamber pressure 5kPa. A constant axial magnetic field with an intensity of 0.15T is applied. Deposition time 15 minutes; After deposition, the structure is annealed in a high-purity argon atmosphere at 600-800℃ for 30 minutes to complete the densification and defect repair. Process parameters: Anneal at 700℃ for 30 minutes in a high-purity argon atmosphere.

[0018] Comparative Example 1: A polyimide insulating varnish (PI) of approximately 8 μm thickness was applied to the same copper wire using conventional processes, representing the typical level of traditional organic insulating materials.

[0019] Comparative Example 2: A pure graphene coating of about 6 μm thick was prepared on copper wire by electrophoretic deposition alone, representing the limit of existing single deposition technology for inorganic carbon materials.

[0020] Comparative Example 3: Using a highly insulating boron nitride nanosheet dispersion (concentration 2 mg / mL) to replace graphene, an insulating underlayer was deposited under the same conditions.

[0021] Comparative Example 4: Only the liquid phase deposition step of Example 1 was performed to form a graphene insulating underlayer, followed by direct high-temperature annealing without vapor phase deposition to grow the CNT layer.

[0022] Performance tests are shown in Table 1.

[0023] Table 1

[0024]

[0025] To demonstrate the repeatability and robustness of the method of the present invention, multiple batches of stability tests were conducted under the conditions of Example 1. The test results are shown in Table 2 below: Table 2

[0026] As shown in Table 2, the coefficients of variation (CV) of the key performance parameters are all less than 5%, indicating that the preparation process of the present invention has high stability and repeatability and is suitable for industrial continuous production.

[0027] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a composite insulating and heat-dissipating structure based on sequential carbon nanotube deposition, characterized in that, Specifically, the steps include the following: Liquid-phase functionalized graphene deposition, gas-phase carbon nanostructure growth, and surface oxidation and high-temperature annealing were performed sequentially. Specific electromagnetic fields were applied at each stage to regulate the material orientation and interface bonding, ultimately resulting in a composite insulating and heat-dissipating structure.

2. The method for preparing a composite insulating and heat-dissipating structure based on sequential carbon nanotube deposition according to claim 1, characterized in that, Specifically, the steps include the following: Copper wires pass continuously through the liquid phase deposition zone at a stable speed. Under the assistance of an alternating electromagnetic field, functionalized graphene is gradually deposited and self-assembled to form a dense insulating underlayer. The carbon source is continuously deposited for 5-30 minutes, allowing it to decompose under the action of a catalyst and grow epitaxially on the graphene substrate, forming a 3-15 μm thick vertically oriented carbon nanostructure reinforcement layer. In the last 1-3 minutes of the deposition process, water vapor or carbon dioxide gas is introduced to gently oxidize the surface of the carbon nanostructure, etch some amorphous carbon and open the tube opening to construct a porous surface structure of micropore-mesopore composite. Copper wire is placed in an inert or reducing atmosphere and subjected to high-temperature annealing at 300-1100℃ for 15-60 minutes to obtain copper wire with a composite insulation and heat dissipation structure.

3. The method for preparing a composite insulating and heat-dissipating structure based on sequential carbon nanotube deposition according to claim 2, characterized in that: The concentration of the functionalized graphene dispersion in the liquid phase deposition zone is 1-10 mg / mL, and an alternating electromagnetic field with an intensity of 0.1-0.8 T is applied to obtain a dense insulating underlayer with a thickness of 0.5-3 μm.

4. The method for preparing a composite insulating and heat-dissipating structure based on sequential carbon nanotube deposition according to claim 2, characterized in that: The solvent for the functionalized graphene dispersion is deionized water or N-methylpyrrolidone, wherein the functionalized graphene is specifically carboxylated graphene or hydroxylated graphene.

5. The method for preparing a composite insulating and heat-dissipating structure based on sequential carbon nanotube deposition according to claim 2, characterized in that: Vertically oriented carbon nanostructure reinforcement layers were grown to a thickness of 3-15 μm using an aerosol system under conditions of 700-900℃, 1-10 kPa pressure, and 0.05-0.3 T magnetic field.

6. The method for preparing a composite insulating and heat-dissipating structure based on sequential carbon nanotube deposition according to claim 5, characterized in that: The aerosol system contains 5%-20% hydrocarbon gas and 0.1%-1.0% ferrocene catalyst.

Images