An ultra-thin heat pipe for enhancing heat transfer performance and its manufacturing process

Abstract

The present invention discloses an ultra-thin heat pipe for improving heat transfer performance and a manufacturing process, including the following steps: 1) Immerse a highly thermally conductive copper mesh in a salt solution, take it out and perform oxidation treatment by heating in an air atmosphere; 2) Wash it with deionized water and then immerse it in an acid solution for ultrasonic treatment; 3) Wash it with deionized water and then heat and oxidize it in a mixed gas environment of air and oxygen; 4) Insert the copper mesh into a copper tube, then place it in a sintering furnace and sinter it in a gas environment containing hydrogen. After the treatment is completed, it is cooled to room temperature with the furnace. The tail of the copper tube is sealed, and then a working fluid is injected into the copper tube, evacuated, and the end of the copper tube is sealed and flattened to obtain an ultra-thin heat pipe. The present invention can significantly improve the heat transfer efficiency of the finally prepared ultra-thin heat pipe. At the same time, the copper mesh therein has excellent mechanical properties and thermal stability, which can help ensure long-term high thermal conductivity, guarantee the use effect of the ultra-thin heat pipe, and extend its service life.

Description

Technical Field

[0001] The present invention relates to the technical field of ultra-thin heat pipes, and particularly to an ultra-thin heat pipe for improving heat transfer performance and a manufacturing process thereof. Background Art

[0002] If the heat generated by electronic devices such as chips cannot be dissipated in time during operation, it will affect their working stability, reduce the mean time between failures, and may even burn out the chips in severe cases. Therefore, effectively conducting and handling this part of heat dissipation is crucial for ensuring the working stability and lifespan of the devices.

[0003] Heat pipes are currently widely used in the heat dissipation of components. They consist of a metal tube and a capillary structure layer on the inner wall of the tube, and contain a heat dissipation fluid inside. When one end of the heat pipe is heated, the fluid absorbs heat and vaporizes to form high-temperature gas. At the other end of the heat pipe, due to the lower temperature, the high-temperature gas condenses into a liquid fluid, and the liquid fluid returns to the heated end under the capillary force of the capillary structure layer, repeating this process to form a continuous phase change heat transfer system. For example, the heat pipe and its manufacturing method disclosed in Patent CN101634532A, a composite heat pipe structure disclosed in Patent CN102331205A, a composite structure ultra-thin heat pipe and its manufacturing method disclosed in Patent CN102410765A, etc.

[0004] Due to the process method of improving the capillary structure used in the existing ultra-thin heat pipes, limited by the external dimensions, the internal space is very narrow, so the available capillary structure size is limited, and the powder sintering-related capillary structure cannot be used. Therefore, the currently used capillary structure is mainly a braided wire structure installed in the narrow space of the ultra-thin heat pipe, but its porosity and specific surface area are still not high enough, and the heat transfer efficiency still needs to be further improved. Moreover, while improving the heat transfer efficiency, the mechanical properties and temperature resistance should also be considered to ensure its service life. The manufacturing process of sandblasting inside the tube for an ultra-thin heat pipe to increase the capillary structure disclosed in Patent CN113701535A forms an uneven shape on the inner surface of the copper tube by sandblasting, increasing the specific surface area of the inner surface of the copper tube and improving the heat transfer efficiency of the ultra-thin heat pipe. However, the increase in the capillary structure is limited, and it will inevitably damage the mechanical strength and other properties of the copper tube, easily leading to a shortened service life.

[0005] Therefore, it is necessary to improve the existing technology to provide a more reliable solution. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an ultra-thin heat pipe for improving heat transfer performance and a manufacturing process thereof in view of the deficiencies in the above-mentioned existing technology.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is as follows: In the first aspect of the present invention, a manufacturing process for an ultra-thin heat pipe with improved heat transfer performance is provided, including the following steps:

[0008] 1) Immerse the high thermal conductivity copper mesh in a salt solution, take it out and heat it in an air atmosphere for oxidation treatment, and cool it to room temperature after the treatment is completed;

[0009] 2) Wash the copper mesh obtained in step 1) with deionized water and then immerse it in an acid solution for ultrasonic treatment;

[0010] 3) Wash the copper mesh obtained in step 2) with deionized water and then heat and oxidize it in a mixed gas environment of air and oxygen;

[0011] 4) Insert the copper mesh obtained in step 3) into a copper tube, then place the copper tube in a sintering furnace and sinter it in a gas environment containing hydrogen. After the treatment is completed, cool it to room temperature with the furnace. Seal the tail of the copper tube, then inject a working fluid into the copper tube, evacuate it, and flatten the end of the copper tube after sealing to obtain an ultra-thin heat pipe.

[0012] Preferably, the manufacturing process for the ultra-thin heat pipe with improved heat transfer performance includes the following steps:

[0013] 1) Immerse the high thermal conductivity copper mesh in a sodium chloride solution with a mass concentration of 15 - 40% for 2 - 10 min, take it out and heat it in an air atmosphere at 110 - 130 °C for 15 - 60 min, and cool it to room temperature;

[0014] 2) Wash the copper mesh obtained in step 1) with deionized water and then immerse it in citric acid with a mass concentration of 15 - 45% for ultrasonic treatment for 15 - 60 min;

[0015] 3) Wash the copper mesh obtained in step 2) with deionized water and then heat and oxidize it in a mixed gas environment of air and oxygen with a volume ratio of 1:2 - 2:1 at 110 - 130 °C for 0.5 - 2 h;

[0016] 4) Insert the copper mesh obtained in step 3) into a copper tube with a wall thickness of 0.1 - 0.5 mm, then place the copper tube in a sintering furnace and sinter it in a low-hydrogen mixed gas environment at 850 - 900 °C for 1 - 4 h, cool it to room temperature with the furnace. Seal the tail of the copper tube, then inject a working fluid into the copper tube, evacuate it, and flatten the end of the copper tube after sealing to a thickness of 1 - 5 mm to obtain an ultra-thin heat pipe;

[0017] Among them, the width D of the copper mesh and the inner diameter r of the copper tube satisfy the following relationship:

[0018]

[0019] Among them, the working fluid is ultrapure water or ethanol.

[0020] Preferably, the manufacturing process of the ultra-thin heat pipe for enhancing heat transfer performance includes the following steps:

[0021] 1) Immerse the high thermal conductivity copper mesh in a sodium chloride solution with a mass concentration of 30% for 5 minutes. After taking it out, heat-treat it in an air atmosphere at 120 °C for 30 minutes, and then cool it to room temperature;

[0022] 2) Wash the copper mesh obtained in step 1) with deionized water and then immerse it in citric acid with a mass concentration of 30%, and perform ultrasonic treatment for 30 minutes;

[0023] 3) After washing the copper mesh obtained in step 2) with deionized water, heat and oxidize it in a mixed gas environment of air and oxygen with a volume ratio of 1:1 at 120 °C for 1 hour;

[0024] 4) Insert the copper mesh obtained in step 3) into a copper tube with a wall thickness of 0.2 mm. Then place the copper tube in a sintering furnace, sinter it in a low-hydrogen mixed gas environment at 880 °C for 2 hours, cool it to room temperature with the furnace, seal the tail of the copper tube, then inject the working fluid into the copper tube, evacuate it, and after sealing the end of the copper tube, flatten it to a thickness of 3 mm to obtain the ultra-thin heat pipe;

[0025] Among them, the low-hydrogen mixed gas consists of N with a volume fraction of 95% 2 and 5% of H 2 ;

[0026] Among them, the length of the copper mesh is not less than the length of the copper tube, and the width D of the copper mesh and the inner diameter r of the copper tube satisfy the following relationship:

[0027]

[0028] Among them, the working fluid is ultrapure water.

[0029] Preferably, the high thermal conductivity copper mesh is prepared from a high thermal conductivity copper alloy. The preparation raw materials of the high thermal conductivity copper alloy include, by mass percentage:

[0030] Mn: 0.22 - 0.67%; Co: 0.19 - 0.74%; Ag: 0.05 - 0.17%; Cr: 0.85 - 1.33%; Zr: 0.20 - 0.45%; Ni@SWCNT@Fe: 2.50 - 4.00%; surface-modified TiC: 2.20 - 3.50%; and the balance is copper;

[0031] The Ni@SWCNT@Fe is a coated and filled modified carbon nanotube containing a sacrificial element component, and the sacrificial element component therein is Fe.

[0032] Preferably, the raw materials for preparing the high thermal conductivity copper alloy include, by mass percentage:

[0033] Mn: 0.35%; Co: 0.41%; Ag: 0.09%; Cr: 1.10%; Zr: 0.29%; Ni@SWCNT@Fe: 3.75%; surface modified TiC: 2.80% and the balance of copper.

[0034] Preferably, the high thermal conductivity copper mesh is prepared by the following method:

[0035] 1-1) Add all raw materials into a ball mill according to the mass ratio, ball mill for 1-4 h under argon protection, with a ball-to-material ratio of 9:1 - 6:1 and a rotation speed of 200-500 rpm;

[0036] 1-2) Add the ball-milled raw materials into a vacuum melting furnace, evacuate to 0.1-0.3 Pa, then heat to 1250-1500 °C under argon protection, melt for 10-30 min, and vacuum cast to obtain an ingot;

[0037] 1-3) Keep warm at 850-950 °C for 1-4 h for homogenization treatment; then perform rotary forging at 600-800 °C to make a rod with a diameter of 5-20 mm, and perform normal temperature drawing after cooling to room temperature to make a thick copper wire with a diameter of 2-5 mm;

[0038] 1-4) Heat-treat the thick copper wire at 550-750 °C for 1-5 min under argon protection, and then draw it through a wire drawing die to obtain a fine copper wire with a diameter of 0.02-0.2 mm;

[0039] 1-5) Keep the fine copper wire at 550-700 °C for 0.5-1 h under argon protection, cool to room temperature to obtain woven copper wire, weave the woven copper wire into a copper mesh through a wire mesh weaving machine, wash the copper mesh successively with ethanol and deionized water, and vacuum dry at 70-100 °C to constant weight to obtain a high thermal conductivity copper mesh with a mesh size of 100-300 meshes.

[0040] Preferably, the coated and filled modified carbon nanotube Ni@SWCNT@Fe is prepared by the following method:

[0041] S1. Pretreatment of single-walled carbon nanotubes;

[0042] Add single-walled carbon nanotubes into a mixed acid composed of concentrated sulfuric acid with a concentration of 95 wt% and concentrated nitric acid with a concentration of 65 wt%, ultrasonically disperse for 15-60 min, then heat to 80-100 °C, stir and reflux for 2-10 h, cool, filter, wash with deionized water to neutrality, and vacuum dry at 70-100 °C to constant weight to obtain pretreated single-walled carbon nanotubes;

[0043] The volume ratio of concentrated sulfuric acid to concentrated nitric acid in the mixed acid is 1:2 - 2:1;

[0044] S2. Preparation of carbon nanotubes filled inside:

[0045] Take 0.5 - 2 g of pretreated single - walled carbon nanotubes, 0.12 - 0.35 g of polyethylene glycol and add them to 50 - 200 mL of deionized water. Then add 0.241 - 0.966 g of ferric nitrate, ultrasonically disperse for 30 - 90 min, and then drop - wise add 10 - 30 mL of ammonia water with a mass concentration of 15 - 25%. After the addition is completed, stir for 5 - 30 min. Transfer the obtained dispersion mixture 1 to a reaction kettle lined with polytetrafluoroethylene, react at 190 - 200 °C for 1 - 4 h, filter, wash the solid product with deionized water, and vacuum - dry at 80 - 100 °C for 4 - 12 h to obtain carbon nanotubes filled inside;

[0046] S3. Preparation of Ni@SWCNT@Fe:

[0047] Take 0.5 - 2 g of carbon nanotubes filled inside and add them to 100 - 400 mL of deionized water. Ultrasonically disperse at 50 - 65 °C for 0.5 - 2 h, then add 0.27 - 1.1 g of nickel nitrate, ultrasonically disperse for 1 - 4 h. Transfer the obtained dispersion mixture 2 to a reaction kettle lined with polytetrafluoroethylene, react at 190 - 220 °C for 1.5 - 6 h, filter, wash the solid product with deionized water, vacuum - dry at 90 - 110 °C for 2 - 8 h, and finally calcine at 1000 - 1150 °C for 1.5 - 6 h in the atmosphere of reducing gas to obtain Ni@SWCNT@Fe.

[0048] Among them, the reducing gas is H 2 or CO.

[0049] Preferably, the coated and filled modified carbon nanotubes Ni@SWCNT@Fe are prepared by the following method:

[0050] S1 - 1. Pretreatment of single - walled carbon nanotubes;

[0051] Add 2 g of single - walled carbon nanotubes to 200 mL of a mixed solution composed of concentrated sulfuric acid with a concentration of 95 wt% and concentrated nitric acid with a concentration of 65 wt% in a volume ratio of 1:1, ultrasonically disperse for 30 min, then heat to 90 °C, stir and reflux for 4 h, cool, filter, wash with deionized water until neutral, and vacuum - dry at 80 °C to constant weight to obtain pretreated single - walled carbon nanotubes;

[0052] S1 - 2. Preparation of carbon nanotubes filled inside:

[0053] Take 1 g of pretreated single-walled carbon nanotubes and 0.2 g of polyethylene glycol and add them to 100 mL of deionized water. Then add 0.483 g of iron nitrate, ultrasonically disperse for 45 min, and then dropwise add 15 mL of ammonia water with a mass concentration of 20%. After the addition is complete, stir for 10 min. Transfer the obtained dispersion mixture 1 to a reaction kettle with a polytetrafluoroethylene inner liner, react at 195 °C for 2 h, filter, wash the solid product with deionized water, and vacuum dry at 90 °C for 6 h to obtain carbon nanotubes filled inside;

[0054] S1-3. Preparation of Ni@SWCNT@Fe:

[0055] Take 1 g of carbon nanotubes filled inside and add them to 200 mL of deionized water. Ultrasonically disperse at 60 °C for 1 h, then add 0.55 g of nickel nitrate, and ultrasonically disperse for 2 h. Transfer the obtained dispersion mixture 2 to a reaction kettle with a polytetrafluoroethylene inner liner, react at 200 °C for 3 h, filter, wash the solid product with deionized water, and vacuum dry at 100 °C for 4 h. Finally, calcine at 1050 °C for 3 h in an H 2 atmosphere to obtain Ni@SWCNT@Fe.

[0056] Preferably, the surface-modified TiC is prepared by the following method:

[0057] S2-1. Pretreatment:

[0058] Wash TiC particles with a particle size of 1 - 10 μm, and then successively carry out roughening, sensitization treatment and activation treatment to obtain pretreated TiC;

[0059] Add copper nitrate and cerium nitrate to deionized water, stir until completely dissolved, then add citric acid and boric acid, stir until completely dissolved, adjust the pH to 10.5 - 11.5 with sodium hydroxide, add pretreated TiC, and then add sodium hypophosphite. Carry out electroless plating treatment on pretreated TiC with the obtained plating solution;

[0060] The concentrations of each component in the obtained plating solution are: copper nitrate 14.5 - 21 g / L, cerium nitrate 3.5 - 4.5 g / L, citric acid 11 - 18 g / L, sodium hypophosphite 15 - 25 g / L, boric acid 10 - 24 g / L;

[0061] The electroless plating process conditions are: pH is 10.5 - 11.5, mechanical stirring is 300 - 650 r / min, temperature: 80 - 90 °C, time: 1 - 3 h;

[0062] After electroless plating, filter, wash the solid particles with deionized water, and vacuum dry at 90 - 100 °C for 4 - 12 h to obtain surface-modified TiC.

[0063] In a second aspect of the present invention, there is provided an ultra-thin heat pipe, characterized in that it is produced by the process described above.

[0064] The beneficial effects of the present invention are as follows:

[0065] The present invention provides a manufacturing process for an ultra-thin heat pipe with improved heat transfer performance. By improving the manufacturing process of the heat pipe, the alloy material of the copper mesh used in the heat pipe manufacturing, and the coordination between the copper mesh and the heat pipe manufacturing process, the heat transfer efficiency of the finally prepared ultra-thin heat pipe can be significantly improved. At the same time, the copper mesh also has excellent mechanical properties and thermal stability, which is conducive to ensuring long-term high thermal conductivity, can ensure the use effect of the ultra-thin heat pipe, and extend its service life.

[0066] In the present invention, the copper mesh is first soaked in brine and then heated and oxidized in air to form a certain corrosion layer and initially form micropores; then it is etched by acid soaking to further expand the micropores; then it is heated in an oxygen atmosphere to achieve deep oxidation. In this process, a burr-like oxide layer protrusion structure similar to mountains will be formed on the surface of the originally smooth copper wires in the copper mesh; finally, the copper mesh is inserted into the copper tube and the two are placed in a sintering furnace with a hydrogen-containing atmosphere for sintering. During this process, the reducing hydrogen will remove the oxide layer on the surface of the copper mesh, and the microporous structure and burr-like protrusions on the copper mesh will basically be retained. Under the action of high temperature, metal molecules diffuse and solidify to form a stable microporous and burr protrusion structure, which can increase the number of capillary structures, enhance the capillary force inside the tube, significantly increase the specific surface area of the copper mesh on the inner wall of the heat pipe, increase the effective porosity ratio, increase the contact heat transfer area between the heat pipe and the internal working medium, and ultimately can greatly improve the heat transfer efficiency of the obtained heat pipe and increase the heat dissipation power.

[0067] By improving the alloy formula of the copper mesh substrate, on the one hand, the thermal conductivity of the copper alloy can be further improved, and its mechanical properties, wear resistance and thermal stability can also be effectively improved; on the other hand, by designing a coated and filled modified carbon nanotube containing sacrificial element components: Ni@SWCNT@Fe as a doping component, and cooperating with the acid leaching process of the copper mesh in the manufacturing process of the ultra-thin heat pipe, a large number of nano-scale microporous channels (i.e., capillary structures) can be formed through the preferential solvolysis of the sacrificial element components, which can further increase the capillary force inside the heat pipe, increase the effective porosity ratio of the copper mesh, and increase the heat exchange area between the copper mesh and the working medium, thereby further improving its heat transfer performance, and ultimately improving the heat transfer efficiency of the prepared ultra-thin heat pipe and increasing the heat dissipation power of the heat pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 is a flow chart of the manufacturing process for the ultra-thin heat pipe with improved heat transfer performance of the present invention;

[0069] Figure 2 The electron micrograph of the copper wires in the copper mesh before and after citric acid treatment in step 2) of Example 1;

[0070] Figure 3 The XRD pattern of Ni@SWCNT@Fe prepared in Example 1;

[0071] Figure 4 The XRD pattern of the surface-modified TiC prepared in Example 1;

[0072] Figure 5 The physical object of the high thermal conductivity copper mesh prepared in Example 1;

[0073] Figure 6 The physical object diagram of the ultra-thin heat pipe in a specific application example;

[0074] Figure 7 The physical object diagram after the two ends of the ultra-thin heat pipe are disassembled;

[0075] Figure 8 The test result of the tensile property test;

[0076] Figure 9 The test result of the thermal resistance. Specific implementation mode

[0077] The following further elaborates on the present invention in combination with examples, so that those skilled in the art can implement it with reference to the text of the specification.

[0078] It should be understood that the terms such as "having", "comprising" and "including" used herein do not exclude the presence or addition of one or more other elements or their combinations.

[0079] Unless otherwise specified, the test methods used in the following examples are all conventional methods. The materials, reagents, etc. used in the following examples can all be obtained from commercial channels unless otherwise specified. For those not specifying specific conditions in the following examples, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For those reagents or instruments not specifying the manufacturer, they are all conventional products that can be purchased commercially.

[0080] Referring to Figure 1 , the present invention provides a manufacturing process for an ultra-thin heat pipe with improved heat transfer performance, including the following steps:

[0081] (1) Immerse the high thermal conductivity copper mesh in a sodium chloride solution with a mass concentration of 15-40% for 2-10 minutes, take it out and heat-treat it in an air atmosphere at 110-130°C for 15-60 minutes, and then cool it to room temperature;

[0082] (2) Wash the copper mesh obtained in step (1) with deionized water and then immerse it in citric acid with a mass concentration of 15-45%, and perform ultrasonic treatment for 15-60 min;

[0083] (3) Wash the copper mesh obtained in step (2) with deionized water, and then heat and oxidize it for 0.5-2 h in a mixed gas environment with a volume ratio of air to oxygen of 1:2-2:1 at 110-130 °C;

[0084] (4) Insert the copper mesh obtained in step (3) into a copper tube with a wall thickness of 0.1-0.5 mm, then place the copper tube in a sintering furnace, sinter it for 1-4 h at 850-900 °C in a low-hydrogen mixed gas environment, cool it to room temperature with the furnace, seal the tail of the copper tube, then inject the working fluid into the copper tube, evacuate it, and after sealing the end of the copper tube, flatten it to a thickness of 1-5 mm to obtain an ultra-thin heat pipe;

[0085] Among them, the width D of the copper mesh and the inner diameter r of the copper tube satisfy the following relationship:

[0086]

[0087] Among them, the working fluid is ultrapure water or ethanol. The working fluid is also called the working liquid or the heat transfer medium.

[0088] In the present invention, the high thermal conductivity copper mesh is prepared from a high thermal conductivity copper alloy. The preparation raw materials of the high thermal conductivity copper alloy include, by mass percentage:

[0089] Mn: 0.22-0.67%; Co: 0.19-0.74%; Ag: 0.05-0.17%; Cr: 0.85-1.33%; Zr: 0.20-0.45%; Ni@SWCNT@Fe: 2.50-4.00%; surface-modified TiC: 2.20-3.50% and the balance of copper;

[0090] Ni@SWCNT@Fe is a coated and filled modified carbon nanotube containing a sacrificial element component, and the sacrificial element component therein is Fe. When the copper mesh is immersed in an acid solution for treatment, the sacrificial element component can dissolve preferentially to Cu.

[0091] In the present invention, the high thermal conductivity copper mesh is prepared by the following method:

[0092] 1-1) Add all the raw materials to a ball mill according to the mass ratio, ball mill for 1-4 h under argon protection, with a ball-to-material ratio of 9:1-6:1 and a rotation speed of 200-500 rpm;

[0093] 1-2) Add the ball-milled raw materials to a vacuum melting furnace, evacuate to 0.1-0.3 Pa, then heat up to 1250-1500 °C under argon protection, melt for 10-30 min, and vacuum cast to obtain an ingot;

[0094] 1-3) Insulate at 850 - 950 °C for 1 - 4 h for homogenization treatment; then perform rotary forging at 600 - 800 °C to make a bar with a diameter of 5 - 20 mm, and perform cold drawing at room temperature after cooling to room temperature to make a thick copper wire with a diameter of 2 - 5 mm;

[0095] 1-4) Heat-treat the thick copper wire under argon protection at 550 - 750 °C for 1 - 5 min, and then draw it through a wire drawing die to obtain a fine copper wire with a diameter of 0.02 - 0.2 mm;

[0096] 1-5) Insulate the fine copper wire under argon protection at 550 - 700 °C for 0.5 - 1 h, cool to room temperature to obtain a braided copper wire, braid the braided copper wire into a copper mesh through a wire mesh braiding machine, wash the copper mesh successively with ethanol and deionized water, and vacuum dry at 70 - 100 °C to constant weight to obtain a highly thermally conductive copper mesh with a mesh size of 100 - 300 meshes.

[0097] In the present invention, the coated and filled modified carbon nanotube Ni@SWCNT@Fe is prepared by the following method:

[0098] S1. Pretreatment of single-walled carbon nanotubes;

[0099] Add single-walled carbon nanotubes to a mixed acid composed of concentrated sulfuric acid with a concentration of 95 wt% and concentrated nitric acid with a concentration of 65 wt%, ultrasonically disperse for 15 - 60 min, then heat to 80 - 100 °C, stir and reflux for 2 - 10 h, cool, filter, wash with deionized water until neutral, and vacuum dry at 70 - 100 °C to constant weight to obtain pretreated single-walled carbon nanotubes;

[0100] The volume ratio of concentrated sulfuric acid to concentrated nitric acid in the mixed acid is 1:2 - 2:1;

[0101] S2. Preparation of carbon nanotubes filled inside;

[0102] Take 0.5 - 2 g of pretreated single-walled carbon nanotubes, 0.12 - 0.35 g of polyethylene glycol and add them to 50 - 200 mL of deionized water, then add 0.241 - 0.966 g of iron nitrate, ultrasonically disperse for 30 - 90 min, then dropwise add 10 - 30 mL of ammonia water with a mass concentration of 15 - 25%, stir for 5 - 30 min after dropping, transfer the obtained dispersion mixture 1 to a reaction kettle with a polytetrafluoroethylene inner lining, react at 190 - 200 °C for 1 - 4 h, filter, wash the solid product with deionized water, and vacuum dry at 80 - 100 °C for 4 - 12 h to obtain carbon nanotubes filled inside;

[0103] S3. Preparation of Ni@SWCNT@Fe:

[0104] Take 0.5 - 2 g of carbon nanotube - filled material and add it to 100 - 400 mL of deionized water. Ultrasonically disperse it at 50 - 65 °C for 0.5 - 2 h, then add 0.27 - 1.1 g of nickel nitrate and ultrasonically disperse for 1 - 4 h. Transfer the obtained dispersion mixture 2 to a reaction kettle with a polytetrafluoroethylene liner, react at 190 - 220 °C for 1.5 - 6 h, filter, wash the solid product with deionized water, vacuum - dry at 90 - 110 °C for 2 - 8 h, and finally calcine at 1000 - 1150 °C for 1.5 - 6 h in the atmosphere of reducing gas to obtain Ni@SWCNT@Fe.

[0105] Among them, the reducing gas is H 2 or CO.

[0106] In the present invention, the surface - modified TiC is prepared by the following method:

[0107] S2 - 1, Pretreatment:

[0108] Clean the TiC particles with a particle size of 1 - 10 μm and then successively carry out roughening, sensitization treatment and activation treatment to obtain pretreated TiC;

[0109] S2 - 2, Add copper nitrate and cerium nitrate to deionized water, stir until completely dissolved, then add citric acid and boric acid, stir until completely dissolved, adjust the pH to 10.5 - 11.5 with sodium hydroxide, add the pretreated TiC, and then add sodium hypophosphite, and carry out electroless plating treatment on the pretreated TiC with the obtained plating solution;

[0110] The concentrations of each component in the obtained plating solution are: copper nitrate 14.5 - 21 g / L, cerium nitrate 3.5 - 4.5 g / L, citric acid 11 - 18 g / L, sodium hypophosphite 15 - 25 g / L, boric acid 10 - 24 g / L;

[0111] The electroless plating process conditions are: pH is 10.5 - 11.5, mechanical stirring is 300 - 650 r / min, temperature: 80 - 90 °C, time: 1 - 3 h;

[0112] After the electroless plating is completed, filter, wash the solid particles with deionized water, vacuum - dry at 90 - 100 °C for 4 - 12 h to obtain the surface - modified TiC.

[0113] The present invention also provides an ultra - thin heat pipe, which is manufactured by the above process.

[0114] Through the improvement of the manufacturing process of the heat pipe, the improvement of the alloy material of the copper mesh used in the manufacturing of the heat pipe, and the coordination between the copper mesh and the heat pipe manufacturing process, the heat transfer efficiency of the finally prepared ultra-thin heat pipe can be significantly improved. At the same time, the copper mesh also has excellent mechanical properties, thermal stability, and wear resistance, which can help ensure long-term high thermal conductivity, guarantee the use effect of the ultra-thin heat pipe, and extend its service life. The following combines specific manufacturing processes to elaborate on the main principle of the present invention for better understanding.

[0115] The capillary force of the heat pipe is one of the key factors for realizing its heat transfer function. The capillary force is generated by the capillary structure inside the heat pipe, which can maintain the liquid film state of the working fluid inside the pipe and enable efficient heat transfer (Liu Yanqi. Characterization of Capillary Force and Heat Transfer Performance Analysis of Axial Microgroove Heat Pipes [D]. Lanzhou Jiaotong University [2024-07-09]. DOI: CNKI:CDMD:2.1017.234219.). Therefore, increasing the capillary structure inside the heat pipe and enhancing the capillary force are effective means to improve the heat transfer performance. Based on this, the present invention has made various improvements.

[0116] First aspect: Improvement of the heat pipe manufacturing process

[0117] In the present invention, the copper mesh is first soaked in brine (sodium chloride solution) and then heated and oxidized in air to form a certain corrosion layer and initially form micropores. Then, it is soaked and corroded with an acid (citric acid) to further expand the micropores. (Moreover, the process in this step cooperates with Ni@SWCNT@Fe in the copper mesh substrate to form a large number of nano-scale micropore channels inside the copper mesh substrate, which will be elaborated in detail later).

[0118] Then, through heating in an oxygen atmosphere of a certain purity, deep oxidation is achieved. In this process, a burr-like oxide layer protrusion structure similar to mountains will be formed on the surface of the originally smooth copper wire in the copper mesh.

[0119] Insert the copper mesh into the copper tube. Under the action of stress, the copper mesh will automatically adhere to the inner wall of the copper tube. Finally, the copper tube is placed in a sintering furnace with a hydrogen-containing atmosphere for sintering. During this process, the reducing hydrogen will remove the oxide layer on the surface of the copper mesh, and the micropore structure and burr-like protrusions on the copper mesh will be basically retained. Under the action of high temperature, metal molecules diffuse and take shape to form a stable micropore and burr protrusion structure, which can increase the number of capillary structures, enhance the capillary force inside the tube, significantly increase the specific surface area of the copper mesh on the inner wall of the heat pipe, increase the effective porosity ratio, improve the contact heat transfer area between the heat pipe and the internal working medium, and ultimately greatly improve the heat transfer efficiency of the obtained heat pipe.

[0120] Second aspect: A. Improvement of the copper mesh substrate - Ni@SWCNT@Fe

[0121] Copper has excellent heat transfer ability. Compared with copper wires, making a copper mesh can improve its overall mechanical properties and heat transfer area. The better the heat conduction ability of the copper mesh substrate, the stronger the heat conduction performance of the copper mesh. In the present invention, the copper mesh is woven from fine copper wires with a diameter of 0.02 - 0.2 mm. Therefore, there are certain requirements for the mechanical properties of the fine copper wires, especially their toughness, to ensure a higher qualified rate of the copper mesh. At the same time, the working environment of the copper mesh in the inner wall of the heat pipe is under the contact and impact of the working medium, and the temperature in many application scenarios is relatively high. This requires the copper mesh to have good friction resistance and thermal stability to ensure its heat transfer effect and long service life. By improving the alloy formula of the copper mesh substrate, on the one hand, the heat conduction performance of the copper alloy can be further enhanced, and its mechanical properties, wear resistance, and thermal stability can also be effectively improved, ensuring the stability of the capillary structure. On the other hand, by designing a coated and filled modified carbon nanotube containing sacrificial element components: Ni@SWCNT@Fe as a doping component, combined with the acid leaching process of the copper mesh in the manufacturing process of the ultra-thin heat pipe, a large number of nano-scale microchannel structures (i.e., capillary structures) can be formed through the preferential solvolysis of the sacrificial element components, thereby further increasing the capillary force inside the heat pipe, increasing the effective porosity ratio of the copper mesh, and increasing the heat exchange area between the copper mesh and the working medium, thus further improving the heat transfer performance and increasing the heat dissipation power of the heat pipe.

[0122] In the high thermal conductivity copper alloy components of the present invention, Mn, Co, and Cr can improve the thermal conductivity of the copper alloy to a certain extent. Moreover, Mn can also increase the strength of the alloy and improve its corrosion resistance to a certain extent. Zr can improve the thermal stability and wear resistance of the alloy, and the addition of Ag can improve the mechanical properties of the alloy. The improvement of corrosion resistance is beneficial to enhancing the long-term tolerance ability of the copper tube to the working medium, so that the capillary structure can remain stable for a long time. The improvement of wear resistance is conducive to the capillary structure remaining stable under the long-term impact force of the working medium.

[0123] The main synthesis mechanism of Ni@SWCNT@Fe in the high thermal conductivity copper alloy components of the present invention is as follows:

[0124] (1) First, the single-walled carbon nanotubes are acidified by mixed acid, which can increase the carboxyl group content on their surface, improve their dispersion performance, and facilitate subsequent filling and coating modification;

[0125] (2) Then, iron ions are added to the dispersion of pretreated single-walled carbon nanotubes. Due to the effect of concentration difference and the capillary action formed by the microporous inner cavity of the single-walled carbon nanotubes, the iron ions can automatically enter the inner cavity of the single-walled carbon nanotubes, and bind and adhere through the coordination of carboxyl groups on the inner wall with the iron ions. Then, deposition occurs under the action of ammonia water, and finally iron oxide is formed under high-temperature hydrothermal reaction, enabling the inner cavity of the single-walled carbon nanotubes to be filled with iron oxide, obtaining carbon nanotubes with internal filling; of course, during this process, a certain amount of iron oxide will also be grafted and adhered to the surface of the single-walled carbon nanotubes;

[0126] (3) Then, nickel ions are added to the dispersion of carbon nanotubes with internal filling. They attach to the surface of the single-walled carbon nanotubes by binding with residual functional groups such as carboxyl groups on the surface of the single-walled carbon nanotubes. Since the inner cavity of the single-walled carbon nanotubes has been filled with iron oxide, only a small amount of nickel ions will enter the inner cavity of the single-walled carbon nanotubes; through high-temperature hydrothermal reaction, the nickel ions form oxides and firmly adhere to the single-walled carbon nanotubes;

[0127] Finally, through high-temperature reduction with a reducing gas (H 2 ), the iron oxide is reduced to elemental iron, and the oxides of nickel and cerium are also reduced to the corresponding elements. Eventually, a coated and filled modified carbon nanotube containing sacrificial element components with iron mainly filled in the inner cavity and an iron-nickel composite coated on the outer wall is obtained: Ni@SWCNT@Fe.

[0128] The functions of Ni@SWCNT@Fe constructed in the present invention at least include the following aspects:

[0129] 1. After Ni@SWCNT@Fe is doped into a high-thermal-conductivity copper alloy, during the process of immersing a copper mesh in citric acid for corrosion treatment in the manufacturing process of an ultra-thin heat pipe, since the activity of Fe is stronger than that of Cu, during the acid leaching process, Fe can preferentially react with citric acid to form soluble ferric citrate, so that the Fe filled in the inner cavity of the single-walled carbon nanotubes is gradually dissolved, thus reforming a cavity structure. The formation of the cavity structure generates a capillary effect, which can promote the entry of citric acid into the cavity to further react with the Fe in the cavity, so that the single-walled carbon nanotubes gradually recover the cavity structure. Since the single-walled carbon nanotubes can be uniformly dispersed in the copper alloy matrix, this will enable the cavity structure of the single-walled carbon nanotubes to form a network-like capillary pore structure in the copper alloy matrix. After manufacturing the ultra-thin heat pipe, the capillary force generated by these capillary pore structures can improve the heat transfer ability, increase the porosity, and increase the heat exchange area between the copper pipe and the working medium, ultimately improving the heat transfer efficiency. Of course, during the acid corrosion process, the copper matrix will also undergo a certain degree of surface corrosion, forming a certain microporous structure.

[0130] 2. Single-walled carbon nanotubes have excellent mechanical properties and can significantly improve the mechanical strength of copper alloys, especially toughness, which is beneficial for the preparation of copper wires and can also enhance the mechanical strength of the prepared copper mesh. At the same time, single-walled carbon nanotubes also have excellent thermal conductivity and can improve the thermal conductivity of the copper alloy matrix. However, defects such as poor wettability, difficult dispersion, and easy curling between nanostructured single-walled carbon nanotubes and the metal copper matrix greatly limit their effect on property improvement. In the present invention, the problem can also be solved by constructing a Ni@SWCNT@Fe structural system. In the present invention, the coating of iron and nickel complexes can improve the wettability between single-walled carbon nanotubes and the copper matrix (for example, copper and nickel can be infinitely miscible), promoting the uniform dispersion of single-walled carbon nanotubes in the copper matrix. The iron and nickel coated on the single-walled carbon nanotubes infiltrate and dissolve with the copper matrix, which can significantly improve the interfacial bonding force and promote the strengthening effect of single-walled carbon nanotubes on the mechanical strength of the matrix. Moreover, the addition of nickel elements can also improve the mechanical strength and corrosion resistance of the copper matrix. The improvement of the mechanical strength of the matrix by single-walled carbon nanotubes can also compensate for the loss of mechanical strength caused by the formation of cavity structures due to acid leaching corrosion.

[0131] 3. In the present invention, Fe preoccupies the inner cavity of single-walled carbon nanotubes, which can prevent other unexpected components from occupying its inner cavity. After Fe fills the inner cavity of single-walled carbon nanotubes, its overall density will increase, and the density difference with the copper alloy matrix will decrease, which is beneficial for the dispersion of single-walled carbon nanotubes in the copper alloy melt. Moreover, the filling of Fe can also reduce the curling of single-walled carbon nanotubes, which is beneficial for improving the properties of the matrix. The uniform dispersion of single-walled carbon nanotubes in the copper alloy can form a network structure, which is very beneficial for improving thermal conductivity and mechanical properties.

[0132] Second aspect: B. Improvement of the copper mesh substrate - TiC

[0133] The addition of TiC ceramic particles can improve the wear resistance, corrosion resistance, and thermal stability of metal substrates (Bai Fang. Research on the microstructure and properties of in-situ nano-TiC_x particle-reinforced copper matrix composites [D]. Jilin University [2024-07-09]. DOI: CNKI: CDMD: 2.1017.156584.). The improvement of wear resistance, corrosion resistance, and thermal stability is beneficial for the copper mesh to cope with the convective impact force and corrosion caused by the heat exchange medium during the working process, as well as the matrix fatigue caused by the temperature environment, and can ensure the stability of the micro-porous structure on it.

[0134] However, TiC is difficult to disperse uniformly in the copper matrix, which will seriously affect the improvement of its performance. In the present invention, by subjecting TiC particles to electroless copper plating surface treatment and compounding rare earth cerium in the copper layer composition, the compatibility between TiC particles and the copper matrix can be effectively improved, and its uniform dispersion can be promoted. During the electroless plating process, due to the high activity of rare earth Ce, some Ce can lose electrons and act as a reducing agent, which can accelerate the deposition of copper. After Ce enters the copper alloy matrix, it can form intermetallic compounds, improving the strength, toughness and high-temperature stability of the matrix. Ce can also play roles such as refining grains, purifying interfaces, and improving interface bonding strength, and can improve the high-temperature elongation rate (Jiang Jiaxin, Wen Yongqing. The Role and Application of Rare Earths in Copper and Copper Alloys [J]. Rare Earth Information, 2021(5):7.), which is extremely beneficial for the preparation of copper wires. Therefore, rare earth Ce can play a positive promoting effect on both the formation of the coating and the improvement of the performance of the copper alloy matrix.

[0135] The above is the overall concept of the present invention. The following provides detailed examples and comparative examples on this basis to further illustrate the present invention.

[0136] The sources of some raw materials involved in the following examples and comparative examples are as follows:

[0137] Single-walled carbon nanotubes, with an inner diameter of 1 - 2 nm and a length of 20 μm, Jiangsu Xianfeng Nano Materials Technology Co., Ltd.;

[0138] TiC, with a particle size of 4 μm, Suzhou Beike Nano Technology Co., Ltd.

[0139] Example 1

[0140] A manufacturing process for an ultra-thin heat pipe with improved heat transfer performance, comprising the following steps:

[0141] 1) Immerse the high thermal conductivity copper mesh in a sodium chloride solution with a mass concentration of 30% for 5 min, take it out, and heat-treat it in an air atmosphere at 120 °C for 30 min, then cool it to room temperature;

[0142] 2) Wash the copper mesh obtained in step 1) with deionized water and then immerse it in citric acid with a mass concentration of 30%, and perform ultrasonic treatment for 30 min;

[0143] 3) Wash the copper mesh obtained in step 2) with deionized water, and then heat and oxidize it at 120 °C in a mixed gas environment with a volume ratio of air to oxygen of 1:1 for 1 h;

[0144] 4) Insert the copper mesh obtained in step 3) into a copper tube with a wall thickness of 0.2 mm, then place the copper tube in a sintering furnace, sinter at 880 °C for 2 h in a low-hydrogen mixed gas environment, cool it to room temperature with the furnace, weld and seal the tail of the copper tube, then inject the working fluid (deionized water) into the copper tube, evacuate the air, and after welding and sealing the end of the copper tube, flatten it to a thickness of 3 mm to obtain an ultra-thin heat pipe;

[0145] Among them, the low-hydrogen mixed gas consists of N with a volume fraction of 95% 2 and 5% of H 2 ;

[0146] Among them, the length of the copper mesh is not less than the length of the copper tube, and the width D of the copper mesh and the inner diameter r of the copper tube satisfy the following relationship: The inner diameter of the copper tube is designed according to specific usage requirements and there is no specific limitation. For example, as an illustration, in this embodiment, the inner diameter r of the copper tube is 10 mm.

[0147] In this embodiment, the high thermal conductivity copper mesh is prepared from a high thermal conductivity copper alloy. The preparation raw materials of the high thermal conductivity copper alloy include, by mass percentage:

[0148] Mn: 0.35%; Co: 0.41%; Ag: 0.09%; Cr: 1.10%; Zr: 0.29%; Ni@SWCNT@Fe: 3.75%; surface-modified TiC: 2.80% and the balance of copper.

[0149] Ni@SWCNT@Fe is a coated and filled modified carbon nanotube containing a sacrificial element component, and the sacrificial element component therein is Fe.

[0150] In this embodiment, the high thermal conductivity copper mesh is prepared by the following method:

[0151] 1-1) Add all the raw materials (Mn powder, Co powder, Ag powder, Cr powder, Zr powder, Ni@SWCNT@Fe, surface-modified TiC particles and copper powder) to a ball mill according to the mass ratio, ball mill for 2 h under argon protection, with a ball-to-material ratio of 7:1 and a rotation speed of 300 rpm;

[0152] 1-2) Add the ball-milled raw materials to a vacuum melting furnace, evacuate to 0.1 Pa, then heat up to 1350 °C under argon protection and melt for 22 min, and vacuum cast to obtain an ingot;

[0153] 1-3) Keep it at 900 °C for 2 h for homogenization treatment; then perform rotary forging at 750 °C to make a bar with a diameter of 10 mm, and perform normal-temperature drawing after cooling to room temperature to make a thick copper wire with a diameter of 2 mm;

[0154] 1-4) The thick copper wire is heat-treated at 700 °C for 30 s under argon protection, and then drawn through a multi-channel wire drawing die to obtain a fine copper wire with a diameter of 0.05 mm (when performing each wire drawing, the copper wire is infiltrated with wire drawing oil, which can prevent the copper wire from being scratched and damaged, improve the surface finish of the copper wire, and at the same time extend the service life of the wire drawing die);

[0155] 1-5) The fine copper wire is kept at 600 °C for 0.5 h under argon protection and cooled to room temperature to obtain a braided copper wire. The braided copper wire is woven into a copper mesh through a metal wire mesh weaving machine. The copper mesh is washed successively with ethanol and deionized water and vacuum dried at 80 °C to constant weight to obtain a high thermal conductivity copper mesh with a mesh size of 200 meshes.

[0156] In this example, the coated and filled modified carbon nanotube Ni@SWCNT@Fe is prepared by the following method:

[0157] S1-1. Pretreatment of single-walled carbon nanotubes;

[0158] Add 2 g of single-walled carbon nanotubes to 200 mL of a mixed solution composed of concentrated sulfuric acid with a concentration of 95 wt% and concentrated nitric acid with a concentration of 65 wt% in a volume ratio of 1:1. Ultrasonically disperse for 30 min, then heat to 90 °C, stir and reflux for 4 h, cool, filter, wash with deionized water until neutral, and vacuum dry at 80 °C to constant weight to obtain pretreated single-walled carbon nanotubes;

[0159] S1-2. Preparation of carbon nanotubes filled inside:

[0160] Take 1 g of pretreated single-walled carbon nanotubes and 0.2 g of polyethylene glycol and add them to 100 mL of deionized water. Then add 0.483 g of iron nitrate. Ultrasonically disperse for 45 min and then dropwise add 15 mL of ammonia water with a mass concentration of 20%. After the addition is complete, stir for 10 min. The obtained dispersed mixture 1 is transferred to a reaction kettle with a polytetrafluoroethylene inner lining and reacted at 195 °C for 2 h. Filter, wash the solid product with deionized water, and vacuum dry at 90 °C for 6 h to obtain carbon nanotubes filled inside;

[0161] S1-3. Preparation of Ni@SWCNT@Fe:

[0162] Take 1 g of carbon nanotubes filled inside and add them to 200 mL of deionized water. Ultrasonically disperse at 60 °C for 1 h, then add 0.55 g of nickel nitrate and ultrasonically disperse for 2 h. The obtained dispersed mixture 2 is transferred to a reaction kettle with a polytetrafluoroethylene inner lining and reacted at 200 °C for 3 h. Filter, wash the solid product with deionized water, and vacuum dry at 100 °C for 4 h. Finally, calcine in an atmosphere of H 2 at 1050 °C for 3 h to obtain Ni@SWCNT@Fe.

[0163] In this example, the surface-modified TiC is prepared by the following method:

[0164] S2-1, Pretreatment:

[0165] After cleaning the TiC particles with a particle size of 4 μm, they are successively subjected to coarsening, sensitization treatment, and activation treatment to obtain pretreated TiC. The specific steps are as follows:

[0166] S2-1-1, Cleaning: Add 1 g of TiC particles with a particle size of 4 μm to 200 mL of acetone, soak for 30 min with ultrasonic oscillation, filter, and wash with ethanol;

[0167] S2-1-2, Coarsening: Then add it to 150 mL of hydrofluoric acid with a concentration of 10 wt%, stir for 20 min for coarsening treatment, wash with deionized water, and dry at 90 °C for 4 h;

[0168] S2-1-3, Sensitization: Add it to 200 mL of sensitizing solution, carry out sensitization treatment with stirring for 30 min, filter, and wash with deionized water;

[0169] Preparation of sensitizing solution: Take 2.5 g of stannous chloride and 6.5 mL of hydrochloric acid with a mass dispersion of 36% and add them to 100 mL of deionized water, stir evenly to obtain the sensitizing solution;

[0170] S2-1-4, Activation: Add the product of step S2-1-3 to 120 mL of activation solution, impregnate with stirring for 45 min. The components of the activation solution are: palladium dichloride at 0.8 g / L, boric acid at 23 g / L, and hydrochloric acid at 0.45 g / L;

[0171] After activation, filter, wash with deionized water, and dry in vacuum at 70 °C for 4 h to obtain pretreated TiC.

[0172] S2-2, Electroless plating:

[0173] Add copper nitrate and cerium nitrate to deionized water, stir until completely dissolved, then add citric acid and boric acid, stir until completely dissolved, adjust the pH to 11 with sodium hydroxide, add pretreated TiC, and then add sodium hypophosphite. Carry out electroless plating treatment on pretreated TiC with the obtained plating solution;

[0174] The concentrations of each component in the obtained plating solution are: copper nitrate 17 g / L, cerium nitrate 4.2 g / L, citric acid 15 g / L, sodium hypophosphite 20 g / L, boric acid 18 g / L;

[0175] The plating process conditions are: pH = 11, mechanical stirring at 400 r / min, temperature: 85 °C, time: 2 h;

[0176] After electroless plating, filter, wash the solid particles with deionized water, and dry in vacuum at 100 °C for 6 h to obtain surface-modified TiC.

[0177] Reference Figure 5 , which is a physical diagram of the high - thermal - conductivity copper mesh prepared in this embodiment. Figure 6 It is a physical diagram of an ultra - thin heat pipe prepared according to process shape, size and other requirements in a specific application example. It is generally L - shaped and includes a heat source end and a heat dissipation end; Figure 7 It is a physical diagram after disassembling the heat source end and the heat dissipation end of the ultra - thin heat pipe.

[0178] Example 2

[0179] A manufacturing process of an ultra - thin heat pipe for improving heat transfer performance, comprising the following steps:

[0180] 1) Immerse the high - thermal - conductivity copper mesh in a sodium chloride solution with a mass concentration of 30% for 5 min, take it out, heat - treat it in an air atmosphere at 120 °C for 30 min, and cool it to room temperature;

[0181] 2) Wash the copper mesh obtained in step 1) with deionized water and then immerse it in citric acid with a mass concentration of 30%, and perform ultrasonic treatment for 28 min;

[0182] 3) Wash the copper mesh obtained in step 2) with deionized water, and then heat - oxidize it in a mixed gas environment of air and oxygen with a volume ratio of 1:1 at 120 °C for 1 h;

[0183] 4) Insert the copper mesh obtained in step 3) into a copper tube with a wall thickness of 0.2 mm, then place the copper tube in a sintering furnace, sinter it in a low - hydrogen mixed gas environment at 880 °C for 2 h, cool it to room temperature with the furnace, weld and seal the tail of the copper tube, then inject a working fluid (deionized water) into the copper tube, evacuate it, weld and seal the end of the copper tube, and then flatten it to a thickness of 3 mm to obtain an ultra - thin heat pipe;

[0184] Among them, the low - hydrogen mixed gas is composed of N 2 with a volume fraction of 95% and H 2 with a volume fraction of 5%;

[0185] Among them, the length of the copper mesh is not less than the length of the copper tube, and the width D of the copper mesh and the inner diameter r of the copper tube satisfy the following relationship: The inner diameter of the copper tube is designed according to specific usage requirements and there is no specific limitation. For example, as an illustration, in this embodiment, the inner diameter r of the copper tube is 10 mm.

[0186] In this embodiment, the high - thermal - conductivity copper mesh is prepared from a high - thermal - conductivity copper alloy. The preparation raw materials of the high - thermal - conductivity copper alloy include, by mass percentage:

[0187] Mn: 0.35%; Co: 0.43%; Ag: 0.09%; Cr: 1.10%; Zr: 0.29%; Ni@SWCNT@Fe: 3.50%; surface-modified TiC: 2.80% and the balance of copper.

[0188] Ni@SWCNT@Fe is a coated and filled modified carbon nanotube containing sacrificial element components, and the sacrificial element component therein is Fe.

[0189] In this embodiment, the high thermal conductivity copper mesh is prepared by the following method:

[0190] 1-1) Add all raw materials into a ball mill according to the mass ratio, ball mill for 2 h under argon protection, with a ball-to-material ratio of 7:1 and a rotation speed of 300 rpm;

[0191] 1-2) Add the ball-milled raw materials into a vacuum melting furnace, evacuate to 0.1 Pa, then heat up to 1350 °C under argon protection, melt for 22 min, and vacuum cast to obtain an ingot;

[0192] 1-3) Keep warm at 900 °C for 2 h for homogenization treatment; then perform rotary forging at 750 °C to make a rod with a diameter of 10 mm, and perform cold drawing at room temperature after cooling to make a thick copper wire with a diameter of 2 mm;

[0193] 1-4) Heat-treat the thick copper wire at 700 °C for 30 s under argon protection, and then stretch it through a multi-channel wire drawing die to obtain a fine copper wire with a diameter of 0.05 mm (when performing each wire drawing, the copper wire is infiltrated with wire drawing oil, which can prevent the copper wire from being scratched and damaged, improve the surface finish of the copper wire, and at the same time extend the service life of the wire drawing die);

[0194] 1-5) Keep the fine copper wire at 600 °C for 0.5 h under argon protection, cool to room temperature to obtain a braided copper wire, braid the braided copper wire into a copper mesh through a wire mesh braiding machine, wash the copper mesh with ethanol and deionized water in sequence, and vacuum dry at 80 °C to constant weight to obtain a high thermal conductivity copper mesh with a mesh size of 200 meshes.

[0195] In this embodiment, the coated and filled modified carbon nanotube Ni@SWCNT@Fe is prepared by the following method:

[0196] S1-1. Pretreatment of single-walled carbon nanotubes;

[0197] Add 2 g of single-walled carbon nanotubes into 200 mL of a mixed solution composed of concentrated sulfuric acid with a concentration of 95 wt% and concentrated nitric acid with a concentration of 65 wt% in a volume ratio of 1:1, ultrasonically disperse for 30 min, then heat to 90 °C, stir and reflux for 4 h, cool, filter, wash with deionized water until neutral, and vacuum dry at 80 °C to constant weight to obtain pretreated single-walled carbon nanotubes;

[0198] S1-2. Preparation of carbon nanotubes filled inside:

[0199] Take 1 g of pretreated single-walled carbon nanotubes and 0.2 g of polyethylene glycol, add them to 100 mL of deionized water, then add 0.483 g of iron nitrate, ultrasonically disperse for 45 min, and then dropwise add 15 mL of ammonia water with a mass concentration of 20%. After the addition is completed, stir for 10 min. Transfer the obtained dispersed mixture 1 to a reaction kettle with a polytetrafluoroethylene inner lining, react at 195 °C for 2 h, filter, wash the solid product with deionized water, and vacuum dry at 90 °C for 6 h to obtain carbon nanotubes filled inside;

[0200] S1-3. Preparation of Ni@SWCNT@Fe:

[0201] Take 1 g of carbon nanotubes filled inside and add them to 200 mL of deionized water. Ultrasonically disperse at 60 °C for 1 h, then add 0.55 g of nickel nitrate, and ultrasonically disperse for 2 h. Transfer the obtained dispersed mixture 2 to a reaction kettle with a polytetrafluoroethylene inner lining, react at 200 °C for 3 h, filter, wash the solid product with deionized water, vacuum dry at 100 °C for 4 h, and finally calcine at 1050 °C for 3 h in a hydrogen atmosphere to obtain Ni@SWCNT@Fe.

[0202] In this embodiment, the surface-modified TiC is prepared by the following method:

[0203] S2-1. Pretreatment:

[0204] Wash the TiC particles with a particle size of 4 μm and then perform roughening, sensitization treatment and activation treatment in sequence to obtain pretreated TiC. The specific steps are as follows:

[0205] S2-1-1. Washing: Add 1 g of TiC particles with a particle size of 4 μm to 200 mL of acetone, soak for 30 min, ultrasonically oscillate, filter, and wash with ethanol;

[0206] S2-1-2. Roughening: Then add it to 150 mL of hydrofluoric acid with a concentration of 10 wt%, stir for 20 min for roughening treatment, wash with deionized water, and dry at 90 °C for 4 h;

[0207] S2-1-3. Sensitization: Add it to 200 mL of sensitizing solution, perform sensitization treatment with stirring for 30 min, filter, and wash with deionized water;

[0208] Preparation of sensitizing solution: Take 2.5 g of stannous chloride and 6.5 mL of hydrochloric acid with a mass dispersion of 36%, add them to 100 mL of deionized water, and stir evenly to obtain the sensitizing solution;

[0209] S2-1-4, Activation: Add the product of step S2-1-3 into 120 mL of activation solution, and immerse it with stirring for 45 min. The components of the activation solution are: palladium dichloride at 0.8 g / L, boric acid at 23 g / L, and hydrochloric acid at 0.45 g / L;

[0210] After activation, filter, wash with deionized water, and vacuum dry at 70 °C for 4 h to obtain pretreated TiC.

[0211] S2-2, Electroless plating:

[0212] Add copper nitrate and cerium nitrate into deionized water, stir until completely dissolved, then add citric acid and boric acid, stir until completely dissolved, adjust the pH to 11 with sodium hydroxide, add pretreated TiC, and then add sodium hypophosphite. Perform electroless plating treatment on the pretreated TiC with the obtained plating solution;

[0213] The concentrations of each component in the obtained plating solution are: copper nitrate at 17 g / L, cerium nitrate at 4.5 g / L, citric acid at 15 g / L, sodium hypophosphite at 20 g / L, and boric acid at 18 g / L;

[0214] The plating process conditions are: pH is 11, mechanical stirring at 400 r / min, temperature: 85 °C, time: 2 h;

[0215] After electroless plating, filter, wash the solid particles with deionized water, and vacuum dry at 100 °C for 6 h to obtain surface-modified TiC.

[0216] Example 3

[0217] A manufacturing process for an ultra-thin heat pipe for enhancing heat transfer performance, comprising the following steps:

[0218] 1) Immerse the high thermal conductivity copper mesh in a sodium chloride solution with a mass concentration of 30% for 5 min, take it out, heat-treat it in an air atmosphere at 120 °C for 30 min, and cool to room temperature;

[0219] 2) Wash the copper mesh obtained in step 1) with deionized water and then immerse it in citric acid with a mass concentration of 30%, and perform ultrasonic treatment for 30 min;

[0220] 3) Wash the copper mesh obtained in step 2) with deionized water, and then heat and oxidize it in a mixed gas environment of air and oxygen with a volume ratio of 1:1 at 120 °C for 1 h;

[0221] 4) Insert the copper mesh obtained in step 3) into a copper tube with a wall thickness of 0.2 mm, then place the copper tube in a sintering furnace, sinter it in a low-hydrogen mixed gas environment at 880 °C for 2 h, cool it to room temperature with the furnace, weld and seal the tail of the copper tube, then inject the working fluid (deionized water) into the copper tube, evacuate it, and weld and seal the end of the copper tube and then flatten it to a thickness of 3 mm to obtain the ultra-thin heat pipe;

[0222] Among them, the low-hydrogen mixed gas consists of N with a volume ratio of 95% 2 and 5% of H 2 ;

[0223] Among them, the length of the copper mesh is not less than that of the copper tube, and the width D of the copper mesh and the inner diameter r of the copper tube satisfy the following relationship: The inner diameter of the copper tube is designed according to specific usage requirements and there is no specific limitation. For example, by way of illustration, in this embodiment, the inner diameter r of the copper tube is 10 mm.

[0224] In this embodiment, the high thermal conductivity copper mesh is prepared from a high thermal conductivity copper alloy. The preparation raw materials of the high thermal conductivity copper alloy include, by mass percentage:

[0225] Mn: 0.37%; Co: 0.42%; Ag: 0.11%; Cr: 1.10%; Zr: 0.32%; Ni@SWCNT@Fe: 3.75%; surface-modified TiC: 2.85% and the balance of copper.

[0226] Ni@SWCNT@Fe is a coated and filled modified carbon nanotube containing a sacrificial element component, and the sacrificial element component therein is Fe.

[0227] In this embodiment, the high thermal conductivity copper mesh is prepared by the following method:

[0228] 1-1) Add all raw materials to a ball mill according to the mass ratio, ball mill for 2 h under argon protection, with a ball-to-material ratio of 7:1 and a rotation speed of 300 rpm;

[0229] 1-2) Add the ball-milled raw materials to a vacuum melting furnace, evacuate to 0.1 Pa, then heat up to 1350 °C under argon protection and melt for 22 min, and obtain an ingot by vacuum casting;

[0230] 1-3) Keep warm at 900 °C for 2 h for homogenization treatment; then perform rotary forging at 750 °C to make a rod with a diameter of 10 mm, and perform normal-temperature wire drawing after cooling to room temperature to make a thick copper wire with a diameter of 2 mm;

[0231] 1-4) Heat-treat the thick copper wire for 30 s at 700 °C under argon protection, and then stretch it through a multi-channel wire drawing die to obtain a fine copper wire with a diameter of 0.05 mm (when performing each wire drawing, the copper wire is infiltrated with wire drawing oil, which can prevent the copper wire from being scratched and damaged, improve the surface finish of the copper wire, and at the same time extend the service life of the wire drawing die;);

[0232] (1-5) The fine copper wire was kept at 600 °C for 0.5 h under argon protection and then cooled to room temperature to obtain the woven copper wire. The woven copper wire was woven into a copper mesh by a wire mesh weaving machine. The copper mesh was successively washed with ethanol and deionized water and then dried in vacuum at 80 °C to constant weight to obtain a high thermal conductivity copper mesh with a mesh size of 200 mesh.

[0233] In this example, the coated and filled modified carbon nanotube Ni@SWCNT@Fe was prepared by the following method:

[0234] S1-1. Pretreatment of single-walled carbon nanotubes;

[0235] 2 g of single-walled carbon nanotubes were added to 200 mL of a mixed solution composed of concentrated sulfuric acid with a concentration of 95 wt% and concentrated nitric acid with a concentration of 65 wt% in a volume ratio of 1:1. After ultrasonic dispersion for 30 min, it was heated to 90 °C, stirred and refluxed for 4 h, cooled, filtered, washed with deionized water until neutral, and dried in vacuum at 80 °C to constant weight to obtain pretreated single-walled carbon nanotubes;

[0236] S1-2. Preparation of carbon nanotubes filled inside:

[0237] 1 g of pretreated single-walled carbon nanotubes and 0.2 g of polyethylene glycol were added to 100 mL of deionized water, and then 0.483 g of iron nitrate was added. After ultrasonic dispersion for 45 min, 15 mL of ammonia water with a mass concentration of 20% was added dropwise. After the addition was completed, it was stirred for 10 min. The obtained dispersion mixture 1 was transferred to a reaction kettle with a polytetrafluoroethylene inner lining and reacted at 195 °C for 2 h. After filtration, the solid product was washed with deionized water and dried in vacuum at 90 °C for 6 h to obtain carbon nanotubes filled inside;

[0238] S1-3. Preparation of Ni@SWCNT@Fe:

[0239] 1 g of carbon nanotubes filled inside were added to 200 mL of deionized water and ultrasonically dispersed at 60 °C for 1 h. Then 0.60 g of nickel nitrate was added and ultrasonically dispersed for 2 h. The obtained dispersion mixture 2 was transferred to a reaction kettle with a polytetrafluoroethylene inner lining and reacted at 200 °C for 3 h. After filtration, the solid product was washed with deionized water and dried in vacuum at 100 °C for 4 h. Finally, it was calcined in a hydrogen atmosphere at 1050 °C for 3 h to obtain Ni@SWCNT@Fe.

[0240] In this example, the surface-modified TiC was prepared by the following method:

[0241] S2-1. Pretreatment:

[0242] The TiC particles with a particle size of 4 μm were washed and then successively subjected to roughening, sensitization treatment and activation treatment to obtain pretreated TiC. The specific steps are as follows:

[0243] S2-1-1, Cleaning: Add 1 g of TiC particles with a particle size of 4 μm into 200 mL of acetone, soak for 30 min with ultrasonic oscillation, filter, and wash with ethanol;

[0244] S2-1-2, Roughening: Then add it to 150 mL of hydrofluoric acid with a concentration of 10 wt%, stir for 20 min for roughening treatment, wash with deionized water, and dry at 90 °C for 4 h;

[0245] S2-1-3, Sensitization: Add it to 200 mL of sensitizing solution, carry out sensitization treatment with stirring for 30 min, filter, and wash with deionized water;

[0246] Preparation of sensitizing solution: Take 2.5 g of stannous chloride and 6.5 mL of hydrochloric acid with a mass fraction of 36% and add them to 100 mL of deionized water, stir evenly to obtain the sensitizing solution;

[0247] S2-1-4, Activation: Add the product of step S2-1-3 to 120 mL of activation solution, impregnate with stirring for 45 min. The components of the activation solution are: palladium dichloride at 0.8 g / L, boric acid at 23 g / L, and hydrochloric acid at 0.45 g / L;

[0248] After activation, filter, wash with deionized water, and dry in vacuum at 70 °C for 4 h to obtain pretreated TiC.

[0249] S2-2, Electroless plating:

[0250] Add copper nitrate and cerium nitrate to deionized water, stir until completely dissolved, then add citric acid and boric acid, stir until completely dissolved, adjust the pH to 11 with sodium hydroxide, add pretreated TiC, and then add sodium hypophosphite. Carry out electroless plating treatment on pretreated TiC with the obtained plating solution;

[0251] The concentrations of each component in the obtained plating solution are: copper nitrate at 17 g / L, cerium nitrate at 4.5 g / L, citric acid at 15 g / L, sodium hypophosphite at 20 g / L, and boric acid at 18 g / L;

[0252] The plating process conditions are: pH = 11, mechanical stirring at 400 r / min, temperature: 85 °C, time: 2 h;

[0253] After electroless plating, filter, wash the solid particles with deionized water, and dry in vacuum at 100 °C for 6 h to obtain surface-modified TiC.

[0254] Comparative Example 1

[0255] This example is basically the same as Example 1, the difference is only that: in this example, the raw materials for preparing the high thermal conductivity copper alloy include by mass percentage:

[0256] Mn: 0.35%; Co: 0.41%; Ag: 0.09%; Cr: 1.10%; Zr: 0.29%; surface-modified TiC: 2.80% and the balance copper.

[0257] Comparative Example 2

[0258] This example is basically the same as Example 1, except that: in this example, Ni@SWCNT@Fe is prepared by the following method:

[0259] S1-1. Pretreatment of single-walled carbon nanotubes, the same as in Example 1;

[0260] S1-2. Preparation of carbon nanotubes filled inside, the same as in Example 1;

[0261] S1-3. Preparation of Ni@SWCNT@Fe:

[0262] Take 1 g of carbon nanotubes filled inside and add it to 200 mL of deionized water, ultrasonically disperse for 3 h at 60 °C, transfer the obtained dispersion mixture 2 to a reaction kettle with a polytetrafluoroethylene inner liner, react at 200 °C for 3 h, filter, wash the solid product with deionized water, vacuum dry at 100 °C for 4 h, and finally calcine in an atmosphere of H 2 and calcine at 1050 °C for 3 h to obtain SWCNT@Fe.

[0263] Comparative Example 3

[0264] This example is basically the same as Example 1, except that: in this example, the raw materials for preparing the high thermal conductivity copper alloy include, by mass percentage:

[0265] Mn: 0.35%; Co: 0.41%; Ag: 0.09%; Cr: 1.10%; Zr: 0.29%; Ni@SWCNT@Fe: 3.75%; and the balance copper.

[0266] Comparative Example 4

[0267] This example is basically the same as Example 1, except that: in this example, the raw materials for preparing the high thermal conductivity copper alloy include, by mass percentage:

[0268] The raw materials for preparing the high thermal conductivity copper alloy include, by mass percentage:

[0269] Mn: 0.35%; Co: 0.41%; Ag: 0.09%; Cr: 1.10%; Zr: 0.29%; Ni@SWCNT@Fe: 3.75%; TiC: 2.80% and the balance copper.

[0270] Comparative Example 5

[0271] This example is basically the same as Example 1, except that: in this example, the surface-modified TiC is prepared by the following method:

[0272] S2-1. Pretreatment, which is the same as that in Example 1;

[0273] S2-2. Electroless plating:

[0274] Copper nitrate is added to deionized water, stirred until completely dissolved, citric acid and boric acid are added, stirred until completely dissolved, the pH is adjusted to 11 with sodium hydroxide, pretreated TiC is added, and then sodium hypophosphite is added. The pretreated TiC is subjected to electroless plating treatment with the obtained plating solution;

[0275] The concentrations of each component in the obtained plating solution are: copper nitrate 17 g / L, citric acid 15 g / L, sodium hypophosphite 20 g / L, boric acid 18 g / L;

[0276] The plating process conditions are: pH is 11, mechanical stirring is 400 r / min, temperature: 85 °C, time: 2 h;

[0277] After the electroless plating is completed, filtration is carried out, the solid particles are washed with deionized water, and vacuum drying is carried out at 100 °C for 6 h to obtain the surface-modified TiC.

[0278] Performance characterization

[0279] 1. Refer to Figure 2 , the electron micrographs of the copper wires in the copper mesh before and after citric acid treatment (after treatment, it is washed with deionized water) in step 2) of Example 1 (the image of single-walled carbon nanotube SWCNT is shown in the figure). The image on the left in the figure is the image before treatment, and it can be seen that there are a large number of fillers (mainly Fe) inside. The image on the right is the image after treatment, and it can be seen that the fillers inside are significantly reduced; the scale bar in the figure is 1 nm; it can be seen that after citric acid treatment, a large amount of Fe filled inside the single-walled carbon nanotube has been dissolved and removed.

[0280] 2. Refer to Figure 3 , the XRD pattern of Ni@SWCNT@Fe prepared in Example 1;

[0281] 3. Refer to Figure 4 , the XRD pattern of the surface-modified TiC prepared in Example 1.

[0282] Performance testing

[0283] 1. Tensile property testing

[0284] The fine copper wires prepared in steps 1-5) of Examples 1-3 and Comparative Examples 1-5 are subjected to tensile property testing, specifically including:

[0285] 1. The room temperature tensile property test was carried out with reference to the standard "GB / T 34505-2017 Test Method for Room Temperature Tensile Test of Copper and Copper Alloy Materials".

[0286] 2. The high temperature tensile property test was carried out with reference to the above standard to test the tensile strength at 120 °C.

[0287] The test results are shown in Table 1 below and Figure 8 as follows:

[0288] Table 1

[0289]

[0290] From the test results in Table 1 and Figure 8 it can be seen that the fine copper wires in Examples 1-3 have high tensile strength, appropriate elongation at break, and excellent thermal stability. In Comparative Example 1, both the tensile property and thermal stability decreased, which was attributed to the fact that Ni@SWCNT@Fe was not added to the raw materials for preparing the copper alloy; in Comparative Example 2, there was a slight decrease in the tensile property, indicating the enhancing effect of nickel coating in the coated and filled modified carbon nanotubes on the performance; in Comparative Example 3, the thermal stability decreased significantly, which was attributed to the fact that surface-modified TiC was not added to the raw materials for preparing the copper alloy; in Comparative Example 4, unmodified TiC was used in the raw materials for preparing the copper alloy, and it was difficult for TiC to be evenly dispersed, resulting in a decrease in thermal stability; in Comparative Example 5, Ce ions were not added to the electroless plating solution, resulting in a certain decrease in both the tensile property and thermal stability.

[0291] 2. Measure the thermal resistance

[0292] The ultra-thin heat pipes of the examples and comparative examples were fabricated into test samples with a total length of 200 mm, and then the thermal resistance of the heat pipes was tested by using the conventional thermal simulation test method in the industry (refer to Patent CN102326046A Flat Heat Pipe). The specific method is as follows:

[0293] A heating area of 30 mm × 30 mm (in contact with the surface of the electric heater) was given to the first end (i.e., the heat source end) of the heat pipe, and a heat dissipation area of 60 mm × 60 mm (in contact with the surface of the aluminum heat sink) was given to the second end (i.e., the heat dissipation end). At room temperature, the first end of the heat pipe was heated by the electric heater, and the heat Q input by the electric heater, the temperature T at the contact point between the electric heater and the first end of the heat pipe 1 and the temperature T at the contact point between the second end of the heat pipe and the aluminum heat sink 2 were calculated. The thermal resistance R was calculated according to the following formula:

[0294] Unit: °C / W.

[0295] The test results are shown in Table 2 and Figure 9 as follows:

[0296] Table 2

[0297]

[0298] According to Table 2 and Figure 9 the test results, it can be seen that the ultra-thin heat pipes prepared in Examples 1-3 have excellent heat transfer capabilities. In the copper alloy raw material for preparing the copper wire in Comparative Example 1, Ni@SWCNT@Fe was not added, resulting in a significant decrease in its heat transfer capabilities; the heat transfer capabilities of Comparative Example 2 also decreased to a certain extent, attributed to the lack of nickel coating in the coated and filled modified carbon nanotubes; the heat transfer capabilities of Comparative Examples 3-5 remained basically unchanged.

[0299] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to specific details.

Claims

1. A process for manufacturing an ultra-thin heat pipe for improving heat transfer performance, characterized in that: The following steps are involved: 1) Soak the high thermal conductivity copper mesh in a salt solution, take it out and heat it in an air atmosphere for oxidation treatment, and cool it to room temperature after the treatment is completed; 2) washing the copper mesh obtained in step 1) with deionized water, immersing it in an acid solution, and performing ultrasonic treatment; 3) washing the copper mesh obtained in step 2) with deionized water, and then heating and oxidizing it in a mixed gas environment of air and oxygen; 4) inserting the copper mesh obtained in step 3) into the copper tube, and then placing the copper tube in a sintering furnace, sintering the copper tube in a hydrogen-containing gas environment, cooling the copper tube to room temperature with the furnace after the treatment, sealing the tail of the copper tube, and then injecting an actuating fluid into the copper tube, evacuating the tube, sealing the end of the copper tube and flattening it to obtain an ultra-thin heat pipe; The high thermal conductivity copper mesh is prepared by a high thermal conductivity copper alloy, and the raw materials for preparing the high thermal conductivity copper alloy include, by mass percentage: Mn: 0.22-0.67%; Co: 0.19-0.74%; Ag: 0.05-0.17%; Cr: 0.85-1.33%; Zr: 0.20-0.45%; Ni@SWCNT@Fe: 2.50-4.00%; surface modified TiC: 2.20-3.50% and the balance of copper; The Ni@SWCNT@Fe is a coated, filled and modified carbon nanotube containing a sacrificial element component, wherein the sacrificial element component is Fe; The coated, filled and modified carbon nanotube Ni@SWCNT@Fe is prepared by the following method: S1, single-arm carbon nanotube pretreatment; The single-arm carbon nanotubes are added to a mixed acid of 95wt% concentrated sulfuric acid and 65wt% concentrated nitric acid, and ultrasonically dispersed for 15-60min, and then heated to 80-100°C, stirred and refluxed for 2-10h, cooled, filtered, washed with deionized water until neutral, and vacuum dried at 70-100°C to constant weight to obtain pretreated single-arm carbon nanotubes; The volume ratio of concentrated sulfuric acid to concentrated nitric acid in the mixed acid is 1:2-2:1; S2. Preparation of internally filled carbon nanotubes: 0.5-2g of pretreated single-arm carbon nanotubes and 0.12-0.35g of polyethylene glycol are added to 50-200mL of deionized water, and then 0.241-0.966g of ferric nitrate is added. After ultrasonic dispersion for 30-90min, 10-30mL of ammonia water with a mass concentration of 15-25% is added dropwise. After the addition is completed, the mixture is stirred for 5-30min. The obtained dispersed mixture 1 is transferred to a polytetrafluoroethylene-lined reactor, reacted at 190-200°C for 1-4h, filtered, and the solid product is washed with deionized water, and vacuum dried at 80-100°C for 4-12h to obtain internally filled carbon nanotubes; S3. Preparation of Ni@SWCNT@Fe: 0.5-2 g of the inner-filled carbon nanotubes were added to 100-400 mL of deionized water, and ultrasonically dispersed at 50-65° C. for 0.5-2 h, and then 0.27-1.1 g of nickel nitrate was added and ultrasonically dispersed for 1-4 h. The obtained dispersed mixture 2 was transferred to a polytetrafluoroethylene-lined reactor, reacted at 190-220° C. for 1.5-6 h, filtered, and the solid product was washed with deionized water, vacuum dried at 90-110° C. for 2-8 h, and finally calcined at 1000-1150° C. in a reducing gas atmosphere for 1.5-6 h to obtain Ni@SWCNT@Fe; Wherein, the reducing gas is H2 or CO; The surface modified TiC is prepared by the following method: S2-1, pretreatment: After cleaning TiC particles with a particle size of 1-10 μm, they are subjected to coarsening, sensitization and activation treatments in sequence to obtain pretreated TiC; S2-2, adding copper nitrate and cerium nitrate into deionized water, stirring until completely dissolved, then adding citric acid and boric acid, stirring until completely dissolved, adjusting the pH to 10.5-11.5 with sodium hydroxide, adding the pretreated TiC, and then adding sodium hypophosphite, and performing chemical plating on the pretreated TiC with the obtained plating solution; The concentrations of the components in the obtained plating solution are: copper nitrate 14.5-21 g / L, cerium nitrate 3.5-4.5 g / L, citric acid 11-18 g / L, sodium hypophosphite 15-25 g / L, and boric acid 10-24 g / L; The plating process conditions are: pH 10.5-11.5, mechanical stirring 300-650r / min, temperature: 80-90°C, time: 1-3h; After the chemical plating is completed, the solid particles are filtered and washed with deionized water, and vacuum dried at 90-100° C. for 4-12 hours to obtain surface-modified TiC.

2. The manufacturing process of the ultra-thin heat pipe with improved heat transfer performance according to claim 1, characterized in that: The following steps are involved: 1) Soak the high thermal conductivity copper mesh in a sodium chloride solution with a mass concentration of 15-40% for 2-10 minutes, take it out and heat it in an air atmosphere at 110-130° C. for 15-60 minutes, and cool it to room temperature; 2) washing the copper mesh obtained in step 1) with deionized water, immersing it in citric acid with a mass concentration of 15-45%, and ultrasonically treating it for 15-60 minutes; 3) washing the copper mesh obtained in step 2) with deionized water, and then heating and oxidizing it at 110-130° C. and a mixed gas environment with a volume ratio of air to oxygen of 1:2-2:1 for 0.5-2 h; 4) inserting the copper mesh obtained in step 3) into a copper tube with a wall thickness of 0.1-0.5 mm, then placing the copper tube in a sintering furnace, sintering at 850-900° C. for 1-4 h in a low-hydrogen mixed gas environment, cooling to room temperature with the furnace, sealing the tail of the copper tube, and then injecting an actuating fluid into the copper tube, evacuating, sealing the end of the copper tube and flattening it to a thickness of 1-5 mm to obtain an ultra-thin heat pipe; Among them, the width D of the copper mesh and the inner diameter r of the copper tube satisfy the following relationship: The actuating fluid is ultrapure water or ethanol.

3. The manufacturing process of the ultra-thin heat pipe with improved heat transfer performance according to claim 2, characterized in that: The following steps are involved: 1) Soak the high thermal conductivity copper mesh in a 30% sodium chloride solution for 5 minutes, take it out and heat it at 120°C in air for 30 minutes, and cool it to room temperature; 2) washing the copper mesh obtained in step 1) with deionized water, immersing it in 30% citric acid, and ultrasonically treating it for 30 minutes; 3) washing the copper mesh obtained in step 2) with deionized water, and then heating and oxidizing it at 120° C. in a mixed gas environment with a volume ratio of air to oxygen of 1:1 for 1 h; 4) inserting the copper mesh obtained in step 3) into a copper tube with a wall thickness of 0.2 mm, then placing the copper tube in a sintering furnace, sintering at 880° C. for 2 h in a low-hydrogen mixed gas environment, cooling to room temperature with the furnace, sealing the tail of the copper tube, and then injecting an actuating fluid into the copper tube, evacuating the tube, sealing the end of the copper tube and flattening it to a thickness of 3 mm to obtain an ultra-thin heat pipe; The low-hydrogen mixed gas consists of 95% N2 and 5% H2 by volume; Among them, the length of the copper mesh is not less than the length of the copper tube, and the width D of the copper mesh and the inner diameter r of the copper tube satisfy the following relationship: Among them, the operating fluid is ultrapure water.

4. The process for manufacturing an ultra-thin heat pipe for improving heat transfer performance according to claim 1, characterized in that: The raw materials for preparing the high thermal conductivity copper alloy include, by mass percentage: Mn: 0.35%; Co: 0.41%; Ag: 0.09%; Cr: 1.10%; Zr: 0.29%; Ni@SWCNT@Fe: 3.75%; surface modified TiC: 2.80% and the balance of copper.

5. The process for manufacturing an ultra-thin heat pipe for improving heat transfer performance according to claim 1, characterized in that: The high thermal conductivity copper mesh is prepared by the following method: 1-1) Add all raw materials into a ball mill according to the mass ratio, and ball mill for 1-4 hours under argon protection, with a ball-to-material ratio of 9:1-6:1 and a rotation speed of 200-500rpm; 1-2) Add the ball-milled raw materials into a vacuum melting furnace, evacuate to 0.1-0.3 Pa, then heat to 1250-1500° C. under argon protection, melt for 10-30 min, and vacuum cast to obtain an ingot; 1-3) Keep the temperature at 850-950℃ for 1-4h to perform homogenization treatment; then perform rotary forging at 600-800℃ to produce a rod with a diameter of 5-20mm, and then perform room temperature drawing after cooling to room temperature to produce a thick copper wire with a diameter of 2-5mm; 1-4) heat treating the thick copper wire under argon protection at 550-750° C. for 1-5 min, and then drawing the thick copper wire through a wire drawing die to obtain a thin copper wire with a diameter of 0.02-0.2 mm; 1-5) The thin copper wire is kept warm at 550-700° C. for 0.5-1 h under argon protection, and cooled to room temperature to obtain a braided copper wire, and the braided copper wire is weaved into a copper mesh by a wire mesh weaving machine, and the copper mesh is washed with ethanol and deionized water in turn, and vacuum dried at 70-100° C. to constant weight to obtain a high thermal conductive copper mesh with a mesh size of 100-300 meshes.

6. The process for manufacturing an ultra-thin heat pipe for improving heat transfer performance according to claim 1, characterized in that: The coated, filled and modified carbon nanotube Ni@SWCNT@Fe is prepared by the following method: S1-1, single-arm carbon nanotube pretreatment; 2 g of single-arm carbon nanotubes were added to 200 mL of a mixture of 95 wt% concentrated sulfuric acid and 65 wt% concentrated nitric acid in a volume ratio of 1:1, and ultrasonically dispersed for 30 min, then heated to 90° C., stirred and refluxed for 4 h, cooled, filtered, washed with deionized water until neutral, and vacuum dried at 80° C. to constant weight to obtain pretreated single-arm carbon nanotubes; S1-2, preparation of internally filled carbon nanotubes: 1 g of pretreated single-arm carbon nanotubes and 0.2 g of polyethylene glycol were added to 100 mL of deionized water, and then 0.483 g of ferric nitrate was added. After ultrasonic dispersion for 45 min, 15 mL of 20% ammonia water was added dropwise. After the addition was completed, the mixture was stirred for 10 min. The obtained dispersed mixture 1 was transferred to a polytetrafluoroethylene-lined reactor, reacted at 195 ° C for 2 h, filtered, and the solid product was washed with deionized water and vacuum dried at 90 ° C for 6 h to obtain internally filled carbon nanotubes. S1-3. Preparation of Ni@SWCNT@Fe: Take 1 g of the filled carbon nanotubes and add them into 200 mL of deionized water, ultrasonically disperse them at 60 ° C for 1 h, then add 0.55 g of nickel nitrate and ultrasonically disperse them for 2 h. The obtained dispersed mixture 2 is transferred to a polytetrafluoroethylene-lined reactor and reacted at 200 ° C for 3 h. After filtering, the solid product is washed with deionized water, vacuum dried at 100 ° C for 4 h, and finally calcined at 1050 ° C for 3 h in a H2 atmosphere to obtain Ni@SWCNT@Fe.

7. An ultra-thin heat pipe, characterized in that: The method is prepared by the process described in any one of claims 1 to 6.

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