Copper steam cavity capillary core and preparation method and application thereof

Abstract

The invention belongs to the technical field of heat pipe heat transfer and material preparation, and particularly relates to a copper steam cavity capillary core and a preparation method and application thereof. The copper steam cavity capillary core comprises a copper substrate, a copper sulfide nanosheet layer and a nitrogen-doped carbon nano coating, the copper sulphide nanosheet layers vertically grow on the surface of the copper substrate, and the copper sulphide nanosheet layers are arranged in an array mode; the nitrogen-doped carbon nano coating is uniformly coated on the surface of the copper sulfide nano sheet layer. In order to solve the problems that an existing copper steam cavity capillary core is lack of a micro-scale structure, few in bubble nucleation sites, low in heat conductivity, large in interface thermal resistance and the like, the invention provides a composite modification scheme of a copper sulfide nanosheet and a nitrogen-doped carbon nano coating. The surface roughness and the bubble nucleation site density are improved through the copper sulfide nanosheets, and the surface thermal performance is improved through the nitrogen-doped carbon, so that the boiling heat transfer performance and the critical heat flux density are remarkably enhanced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of heat pipe heat transfer and its material preparation technology, and particularly relates to a copper vapor cavity capillary core and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of cloud computing, big data, artificial intelligence and 5G communication technology, the computing power of data center server clusters continues to improve, and the single cabinet heat load has climbed from the traditional 3-5 kW to 20 kW or even higher. The significant increase in heat flux density brought by high power density makes the data center thermal management face severe challenges, and the traditional heat dissipation methods relying on heat conduction or air convection have been difficult to meet the high-efficiency heat dissipation demand.

[0003] As a kind of phase change heat transfer device similar to flat plate heat pipe, vapor cavity relies on latent heat transfer of working fluid-liquid-gas phase change to transfer heat, and its heat transfer capacity is much higher than that of traditional heat dissipation methods, so it has important application value in the heat dissipation of electronic components and high-power density equipment. The capillary core is the core functional component of the vapor cavity, and its surface microstructure and thermal conductivity directly determine the liquid return capacity, bubble nucleation condition and overall boiling heat transfer performance, and plays a decisive role in the heat dissipation efficiency of the vapor cavity.

[0004] However, the existing copper vapor cavity capillary core has the following key technical problems: ① Lack of microscale structure: the surface of the capillary core is smooth, and the number of bubble nucleation sites is insufficient, resulting in low boiling heat transfer efficiency and inability to quickly remove the heat generated by high-power density devices; ② Limited thermal conductivity: the interfacial thermal resistance between the capillary core and the working fluid and the vapor cavity shell is large, and the heat transfer process is seriously wasted, reducing the overall heat transfer capacity of the vapor cavity; ③ Insufficient structure optimization: the existing technology is difficult to balance the increase of surface roughness (increase of nucleation sites) and thermal conductivity (reduction of thermal resistance) of the capillary core at the same time, and lacks an effective and controllable composite modification scheme.

[0005] In view of this, the present application is proposed. SUMMARY

[0006] The purpose of the present application is to provide a copper vapor cavity capillary core and a preparation method and application thereof to solve the problems of lack of microscale structure, few bubble nucleation sites, low thermal conductivity and large interfacial thermal resistance of the existing copper vapor cavity capillary core.

[0007] In order to overcome the shortcomings of the prior art, the present application provides the following technical scheme: A copper vapor cavity capillary core, comprising a copper base, a copper sulfide nanosheet layer and a nitrogen-doped carbon nanocoating; the copper sulfide nanosheet layer is vertically grown on the surface of the copper base, and the copper sulfide nanosheet layer is arranged in an array; the nitrogen-doped carbon nanocoating is uniformly coated on the surface of the copper sulfide nanosheet layer.

[0008] Further, the copper sulfide nanosheet layer is grown by immersing the copper substrate in a basic solution containing sulfide and sublimed sulfur; micro-scale pores are formed between adjacent copper sulfide nanosheets.

[0009] Further, the nitrogen-doped carbon nanocoating is formed by high-temperature annealing of a polydopamine layer coated on the surface of the copper sulfide nanosheet in a nitrogen atmosphere.

[0010] In addition, the application also provides a preparation method of the copper vapor chamber wick as described above, comprising the following steps: S1, copper substrate pretreatment: immerse the copper sheet in an acidic solution and perform ultrasonic cleaning to remove the surface oxide layer of the copper substrate; S2, build a copper sulfide nanosheet layer: immerse the pretreated copper substrate in a basic mixed aqueous solution containing sulfide and sublimed sulfur, and react at room temperature to make the copper sulfide nanosheet grow vertically on the surface of the copper substrate to form a CuS@Cu substrate; S3, build a polydopamine coating layer: place the CuS@Cu intermediate in a mixed solvent containing dopamine and tris-hydroxymethyl aminomethane, and form a uniform polydopamine coating layer on the surface of the copper sulfide nanosheet through a dopamine self-polymerization reaction to obtain a PDA / CuS@Cu substrate; S4, prepare a nitrogen-doped carbon nanocoating: place the PDA / CuS@Cu substrate in a nitrogen atmosphere for high-temperature annealing treatment to carbonize the polydopamine coating layer to form a nitrogen-doped carbon nanocoating, and prepare a copper vapor chamber wick with an NC / CuS@Cu composite structure.

[0011] Further, in step S1, the acidic solution is a hydrochloric acid solution; the concentration of the hydrochloric acid solution is 0.5-2.0 mol / L; and / or the ultrasonic cleaning time is 5-15 min.

[0012] Further, in step S2, in the basic mixed aqueous solution, the sulfide is sodium sulfide with a purity of ≥98% and a concentration of 0.2-0.5 mol / L; the concentration of the sublimed sulfur is 0.1-0.3 mol / L; the basic substance is sodium hydroxide with a concentration of 0.01-0.05 mol / L; and / or the reaction time at room temperature is 10-20 min.

[0013] Further, in step S2, the basic mixed aqueous solution is used after ultrasonic dispersion treatment; the ultrasonic power of the ultrasonic dispersion is 100 W, and the treatment time is 30-40 min.

[0014] Further, in step S3, the mixed solvent is a mixture of ethanol and water, with a volume ratio of ethanol to water of 1:1; the total volume of the mixed solvent is 40 mL; the amount of dopamine is 1-50 mg, the amount of tris(hydroxymethyl)aminomethane is 0.01-0.1 g; and / or, the self-polymerization reaction time of dopamine is 24 h.

[0015] Further, in step S4, the nitrogen flow rate is 100 sccm; and / or, the conditions for the high-temperature annealing treatment are: heating to 600~1000℃ at a heating rate of 5℃ / min, and holding at that temperature for 0.5~2 h.

[0016] In addition, the present invention also provides an application of the copper vapor chamber capillary core as described above or the copper vapor chamber capillary core prepared by the aforementioned method in heat dissipation of electronic components and high power density devices.

[0017] Compared with the prior art, the technical solution of the present invention has at least the following technical effects: This invention addresses the problems of existing copper vapor chamber capillary wicks, such as lack of microscale structure, few bubble nucleation sites, low thermal conductivity, and high interfacial thermal resistance. It proposes a composite modification scheme of "copper sulfide nanosheets + nitrogen-doped carbon (NC) nanocoating." Copper sulfide nanosheets improve surface roughness and bubble nucleation site density, while the nitrogen-doped carbon (NC) nanocoating enhances thermal conductivity, thereby significantly improving boiling heat transfer performance and critical heat flux density. Specifically, the performance is synergistically enhanced: CuS nanosheets significantly increase microscale roughness and nucleation site density, while the NC coating provides a high thermal conductivity path; the two work synergistically to improve boiling heat transfer performance. The structure is highly stable: the vertical nanosheet array structure is maintained after high-temperature annealing, ensuring reliable operation under long-term boiling conditions. The performance improvement is significant: the critical heat flux density (CHF) of NC / CuS@Cu is more than 60% higher than that of pure copper and more than 27% higher than that of CuS-only structures; the heat transfer coefficient (HTC) is more than 159% higher than that of pure copper and more than 34% higher than that of CuS structures.

[0018] In addition, the preparation process of the present invention is simple and controllable. The entire preparation process does not require complex equipment or precision technology. It can be completed by room temperature soaking, solution reaction and conventional high temperature annealing. The process steps are simple, low cost and good repeatability, which is convenient for large-scale industrial production. Attached Figure Description

[0019] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein: Figure 1 A schematic diagram of the preparation process of the copper vapor chamber capillary core; Figure 2 A schematic diagram of the dopamine polymerization and pyrolysis reactions during the preparation of the copper vapor chamber capillary core; Figure 3 The image shows a scanning electron microscope (SEM) image of CuS@Cu, which displays a vertically aligned array of CuS nanosheets. Figure 4 The image shows a scanning electron microscope (SEM) image of PDA / CuS@Cu, which shows that the CuS nanosheets retain a porous structure even after being coated with a PDA layer. Figure 5 This is a scanning electron microscope (SEM) image of NC / CuS@Cu, showing the nanosheet structure that remains vertically aligned even after high-temperature annealing. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Those skilled in the art should understand that the embodiments described are merely illustrative of the invention and should not be considered as specific limitations thereof. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Process parameters not specifically specified in the following embodiments are generally performed under conventional conditions.

[0021] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0022] Introducing micro / nano structures onto the surface of a metal substrate capillary wick can significantly increase the number of nucleation sites, while fabricating a high thermal conductivity coating on it can reduce interfacial thermal resistance and improve heat transfer efficiency. Nitrogen-doped carbon nanotube coatings, in particular, possess advantages such as high thermal conductivity, good thermal stability, and controllable composition, demonstrating significant application potential. This invention focuses on the key technical challenge of constructing a composite structure combining microscale structures and a high thermal conductivity coating on the surface of a copper vapor chamber capillary wick to enhance vapor chamber performance.

[0023] According to a first aspect of the present invention, a copper vapor chamber capillary core is provided, comprising a copper substrate, copper sulfide (CuS) nanosheets, and a nitrogen-doped carbon (NC) nanocoating; the copper sulfide (CuS) nanosheets are vertically grown on the surface of the copper substrate and arranged in an array; the nitrogen-doped carbon (NC) nanocoating is uniformly coated on the surface of the copper sulfide (CuS) nanosheets.

[0024] The copper vapor chamber capillary wick of this invention, with an NC / CuS@Cu composite structure, possesses the advantages of CuS nanosheet structure: high roughness and porosity, increasing bubble nucleation sites and promoting rapid bubble detachment; and the advantages of nitrogen-doped carbon coating: high thermal conductivity and good interfacial bonding, reducing capillary wick thermal resistance and improving heat transfer efficiency. Furthermore, through the synergistic effect of these two components, boiling heat transfer performance is significantly enhanced, achieving simultaneous improvement in CHF and HTC, solving the technical challenge of existing capillary wicks where "improving roughness and thermal conductivity are difficult to achieve simultaneously." The specific synergistic mechanism is as follows: ① Synergistic effect on heat transfer efficiency: The vertically arranged CuS nanosheets construct a porous structure, ensuring capillary reflux of the working fluid; the NC coating (high thermal conductivity) forms a continuous thermally conductive network, reducing the interfacial thermal resistance between the working fluid and the copper substrate. The combination of these two components achieves a dual guarantee of "working fluid circulation + high-efficiency heat conduction," significantly enhancing boiling heat transfer efficiency. ② Synergistic effect of bubble behavior: The high roughness of CuS provides a large number of bubble nucleation sites, reduces the bubble detachment diameter, and accelerates the detachment of bubbles from the heating surface; the NC coating has high thermal conductivity and good wettability, promotes liquid reflux and hinders gas film expansion. The two optimize the "nucleation-detachment" cycle and significantly improve the critical heat flux density (CHF). ③ Synergistic effect of structural stability: The NC coating fixes CuS nanosheets on the copper substrate through "coating-supporting" effect, while isolating the working fluid from corrosion, ensuring the long-term preservation of the CuS porous structure and guaranteeing the long-term stable operation of the steam chamber.

[0025] In the aforementioned copper vapor chamber capillary core, as a preferred embodiment, copper sulfide (CuS) nanosheets are grown by immersing a copper substrate in an alkaline solution containing sulfides and sublimed sulfur; microscale pores are formed between adjacent copper sulfide (CuS) nanosheets; and a nitrogen-doped carbon (NC) nanocoating is formed by annealing a polydopamine layer coated on the surface of the copper sulfide (CuS) nanosheets at high temperature in a nitrogen atmosphere.

[0026] According to a second aspect of the present invention, a method for preparing the copper vapor chamber capillary wick as described above is provided, comprising the following steps: S1. Copper substrate pretreatment: Immerse the copper sheet in an acidic solution and perform ultrasonic cleaning to remove the oxide layer on the surface of the copper substrate; use acid washing and ultrasonic cleaning to remove the surface oxide layer to obtain a clean substrate, providing a good adhesion interface for subsequent coating construction; S2. Construction of copper sulfide nanosheets: The pretreated copper substrate was immersed in an alkaline mixed aqueous solution containing sulfide and sublimed sulfur. The sublimed sulfur reacted with sodium sulfide to generate polysulfide anions (S... x 2- Cu atoms on the copper substrate surface undergo dissolution and oxidation, releasing Cu 2+ With S in solution 2- / S x 2-This combination promotes the in-situ deposition and directional growth of CuS on the copper substrate surface. Influenced by lattice matching and local supersaturation effects, CuS is arranged on the copper surface in the form of vertical nanosheets, forming a porous structure and significantly increasing the number of bubble nucleation sites.

[0027] S3. Constructing a polydopamine coating layer: The CuS@Cu intermediate is placed in a mixed solvent containing dopamine and tris(hydroxymethyl)aminomethane. Through dopamine self-polymerization (dopamine undergoes self-polymerization to form polydopamine PDA, which is uniformly coated on the surface of CuS nanosheets through hydrogen bonding and covalent bonding), a uniform polydopamine coating layer is formed on the surface of copper sulfide nanosheets, resulting in a PDA / CuS@Cu substrate. The formation of a uniform coating layer on the CuS surface using the dopamine self-polymerization method provides a precursor for subsequent carbonization. S4. Preparation of nitrogen-doped carbon nanotube coating: The PDA / CuS@Cu substrate is subjected to high-temperature annealing in a nitrogen atmosphere. (The PDA layer undergoes a carbonization reaction at high temperature, during which the organic functional groups decompose, and carbon elements form a graphene-like carbon nanotube layer. Nitrogen elements are doped into the carbon layer to form a nitrogen-doped carbon (NC) nanotube coating.) This carbonizes the polydopamine coating layer to form a nitrogen-doped carbon nanotube coating, resulting in a copper vapor chamber capillary wick with an NC / CuS@Cu composite structure. High-temperature annealing in an inert atmosphere carbonizes the PDA layer into an NC coating, reducing interfacial thermal resistance and improving overall thermal conductivity.

[0028] In the above preparation method, as a preferred embodiment, in step S1, the acidic solution is a hydrochloric acid solution; the concentration of the hydrochloric acid solution is 0.5~2.0 mol / L; optionally, the ultrasonic cleaning time is 5~15 min.

[0029] In step S2, the alkaline mixed aqueous solution contains sodium sulfide at a concentration of 0.2–0.5 mol / L; sublimed sulfur at a concentration of 0.1–0.3 mol / L; and sodium hydroxide as the alkaline substance, with a purity ≥98% and a concentration of 0.01–0.05 mol / L. Optionally, the reaction time at room temperature is 10–20 min. The alkaline mixed aqueous solution is used after ultrasonic dispersion treatment; the ultrasonic power for ultrasonic dispersion is 100 W, and the treatment time is 30–40 min. To prepare the alkaline mixed aqueous solution, water, sodium hydroxide, sodium sulfide, and sublimed sulfur are mixed and then ultrasonically dispersed.

[0030] In step S3, the mixed solvent is a mixture of ethanol and water, with a volume ratio of ethanol to water of 1:1; the total volume of the mixed solvent is 40 mL; the amount of dopamine is 1-50 mg, and the amount of tris(hydroxymethyl)aminomethane is 0.01-0.1 g; optionally, the dopamine self-polymerization reaction time is 24 h.

[0031] In step S4, the nitrogen flow rate is 100 sccm; optionally, the conditions for the high-temperature annealing treatment are: heating to 600~1000℃ at a heating rate of 5℃ / min, and holding at this temperature for 0.5~2 h.

[0032] According to a third aspect of the present invention, the application of the copper vapor chamber capillary wick described above or the copper vapor chamber capillary wick prepared by the described method in heat dissipation of electronic components and high-power-density devices is provided. The high-power-density electronic devices include, but are not limited to, at least one of data center servers, 5G communication base station core chips, and artificial intelligence computing modules.

[0033] The present invention will now be described in detail with reference to embodiments thereof. These examples are provided by way of explanation and not by way of limitation. In fact, those skilled in the art will recognize that modifications and variations can be made to the present invention without departing from its scope or spirit. For example, a feature shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is desirable that the present invention encompass such modifications and variations that fall within the scope of the appended claims and their equivalents.

[0034] In the embodiments of the present invention, unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0035] Example 1: Preparation of NC / CuS@Cu capillary wick This embodiment provides a method for preparing a copper vapor chamber capillary wick to synergistically improve the micro-roughness and thermal conductivity of the capillary wick. The preparation process of the copper vapor chamber capillary wick is illustrated in the attached diagram. Figure 1 As shown, the specific steps include: (1) Copper surface pretreatment: The smooth copper sheet was immersed in a 1.0 mol / L hydrochloric acid solution and ultrasonically cleaned for 10 min (ultrasonic power 100 W) to remove surface oxides and obtain a clean and activated copper substrate, which provides a good adhesion interface for subsequent coating construction.

[0036] (2) Vertical growth of copper sulfide (CuS) nanosheets: Prepare an aqueous solution (30 mL) containing 0.16 mol / L sublimed sulfur, 0.33 mol / L sodium sulfide and 0.03 mol / L sodium hydroxide. After ultrasonic dispersion for 30 min, vertically immerse the pretreated copper sheet in the solution and react at room temperature (25 ℃) for 10 min. Remove and dry with nitrogen gas to grow vertically arranged CuS nanosheet structures on the copper surface in situ to increase the density of bubble nucleation sites.

[0037] (3) Construction of polydopamine (PDA) coating layer: A copper substrate (CuS@Cu) with CuS nanosheets on its surface was placed in 40 mL of ethanol / water mixed solvent (volume ratio 1:1) with 10 mg of dopamine (DOPA), and 0.01 g of tris(hydroxymethyl)aminomethane (Tris) was added. The reaction was carried out for 24 h (see attached schematic diagram of dopamine polymerization and pyrolysis process). Figure 2 This process allows dopamine to self-polymerize and uniformly coat the surface of CuS nanosheets, resulting in a PDA / CuS@Cu substrate.

[0038] (4) Preparation of nitrogen-doped carbon (NC) nanocoating: The PDA / CuS@Cu substrate was placed in a nitrogen atmosphere (flow rate 100 sccm) and heated to 800℃ at a heating rate of 5℃ / min. It was then calcined at 800℃ for 2 h to carbonize the PDA layer and form a nitrogen-doped carbon nanocoating (NC). After heat treatment, a composite structure (NC / CuS@Cu) with "CuS nanosheets + NC nanocoating" on the surface was obtained.

[0039] Example 2: Structural and Performance Characterization (1) Scanning electron microscopy (SEM) characterization: The morphology of the CuS@Cu, PDA / CuS@Cu and NC / CuS@Cu samples prepared in Example 1 was observed using field emission scanning electron microscopy. The results are as follows: Figure 3 , 4 As shown in Figure 5. Figure 3 It can be seen that CuS nanosheets are arranged vertically on the copper surface, and a large number of microscale pores are formed between adjacent nanosheets; Figure 4 The results show that the porous structure of CuS nanosheets was not destroyed after PDA coating. The PDA layer was uniformly covered on the surface of the nanosheets, and the porous structure remained unchanged, indicating that the PDA layer did not destroy the original morphology of the CuS nanosheets. Figure 5 The results show that after high-temperature carbonization, NC / CuS@Cu still maintains the vertically arranged nanosheet structure, and the NC coating is tightly bonded to the CuS surface, indicating that the composite structure has good high-temperature stability, and has both high surface roughness and high thermal conductivity, which can effectively reduce the thermal resistance of copper capillary.

[0040] (2) Boiling heat transfer performance test: The boiling heat transfer performance of the NC / CuS@Cu capillary core, CuS@Cu substrate and pure copper substrate prepared in Example 1 was compared. Test conditions: The working fluid was deionized water, the saturation temperature was 100 ℃, the initial input power was 10W, and the power was gradually increased in increments of 20 W / step until the critical heat flux (CHF) occurred. The temperature gradient along the heat flux direction and the sample surface temperature were measured by thermocouples. The boiling initiation temperature, superheat (the difference between the sample surface temperature and the working fluid saturation temperature), critical heat flux (CHF) and heat transfer coefficient (HTC) were calculated. The results are shown in Table 1. Table 1 Test results of boiling heat transfer performance of different samples Sample Boiling onset temperature (K) Superheat (K) CHF (W cm -2 )]]> HTC (kW m -2 K -1 )]]> Pure copper 7.2 31.7 114.5 38.2 CuS@Cu 5.2 19.7 145.1 73.6 NC / CuS@Cu 4.1 15.5 184.5 99.1 Table 1 shows that pure copper has the highest surface superheat (31.7 K) and the lowest CHF (114.5 W·cm). -2 HTC's smallest (38.2 kW·m) -2 ·K -1 The boiling heat transfer performance is the worst; the CHF on the CuS@Cu surface is 145.1 W·cm⁻¹. -2 ) and HTC (73.6kW·m -2 ·K -1 The CHF is significantly higher than that of pure copper, mainly due to the rough porous structure formed by the vertical CuS nanosheets; NC / CuS@Cu exhibits the best overall performance, with a CHF of 184.5 W·cm⁻¹. -2 HTC has a power output of 99.1 kW·m. -2 ·K -1 Compared with pure copper, the performance is improved by 61.1% and 159.4% respectively, and compared with CuS@Cu by 27.2% and 34.6% respectively, showing significant performance advantages.

[0041] The foregoing has described and evaluated some embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. This does not affect the essential content of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, still fall within the protection scope of the present invention.

Claims

1. A copper vapor chamber capillary wick, characterized in that, It includes a copper substrate, copper sulfide nanosheets, and a nitrogen-doped carbon nanolayer coating; the copper sulfide nanosheets are vertically grown on the surface of the copper substrate and are arranged in an array; the nitrogen-doped carbon nanolayer coating is uniformly coated on the surface of the copper sulfide nanosheets.

2. The copper vapor chamber capillary wick according to claim 1, characterized in that, The copper sulfide nanosheets are grown by immersing a copper substrate in an alkaline solution containing sulfides and sublimed sulfur; microscale pores are formed between adjacent copper sulfide nanosheets.

3. The copper vapor chamber capillary wick according to claim 1, characterized in that, The nitrogen-doped carbon nanofiber coating is formed by high-temperature annealing of a polydopamine layer coated on the surface of copper sulfide nanosheets in a nitrogen atmosphere.

4. A method for preparing a copper vapor chamber capillary wick as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. Copper substrate pretreatment: Immerse the copper sheet in an acidic solution and perform ultrasonic cleaning to remove the oxide layer on the surface of the copper substrate. S2. Constructing copper sulfide nanosheets: The pretreated copper substrate is immersed in an alkaline mixed aqueous solution containing sulfide and sublimed sulfur, and reacted at room temperature to allow copper sulfide nanosheets to grow vertically on the surface of the copper substrate, forming a CuS@Cu substrate. S3. Constructing a polydopamine coating layer: The CuS@Cu intermediate is placed in a mixed solvent containing dopamine and tris(hydroxymethyl)aminomethane. Through the dopamine self-polymerization reaction, a uniform polydopamine coating layer is formed on the surface of copper sulfide nanosheets to obtain a PDA / CuS@Cu substrate. S4. Preparation of nitrogen-doped carbon nanofiber coating: The PDA / CuS@Cu substrate is placed in a nitrogen atmosphere for high-temperature annealing treatment, so that the polydopamine coating layer is carbonized to form a nitrogen-doped carbon nanofiber coating, and a copper vapor chamber capillary with NC / CuS@Cu composite structure is obtained.

5. The preparation method according to claim 4, characterized in that, In step S1, the acidic solution is a hydrochloric acid solution; the concentration of the hydrochloric acid solution is 0.5~2.0 mol / L; and / or, the ultrasonic cleaning time is 5~15 min.

6. The preparation method according to claim 4, characterized in that, In step S2, the alkaline mixed aqueous solution contains sodium sulfide with a purity ≥98% and a concentration of 0.2~0.5 mol / L; sublimed sulfur with a concentration of 0.1~0.3 mol / L; and sodium hydroxide with a concentration of 0.01~0.05 mol / L. The reaction time at room temperature is 10~20 min.

7. The preparation method according to claim 6, characterized in that, In step S2, the alkaline mixed aqueous solution is used after ultrasonic dispersion treatment; the ultrasonic power of the ultrasonic dispersion is 100 W, and the treatment time is 30~40 min.

8. The preparation method according to claim 4, characterized in that, In step S3, the mixed solvent is a mixture of ethanol and water, with a volume ratio of ethanol to water of 1:1; the total volume of the mixed solvent is 40 mL; the amount of dopamine is 1-50 mg, the amount of tris(hydroxymethyl)aminomethane is 0.01-0.1 g; and / or, the self-polymerization reaction time of dopamine is 24 h.

9. The preparation method according to claim 4, characterized in that, In step S4, the nitrogen flow rate is 100 sccm; and / or, the conditions for the high-temperature annealing treatment are: heating to 600~1000℃ at a heating rate of 5℃ / min, and holding at that temperature for 0.5~2 h.

10. The application of a copper vapor chamber capillary as described in any one of claims 1 to 3 or a copper vapor chamber capillary prepared by any one of claims 4 to 9 in heat dissipation of electronic components and high power density devices.

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