A porous structure board of a high thermal conductivity nano thermal cable and a preparation method thereof

Abstract

The present invention provides a highly thermally conductive nanoporous structure board made of nanothermal cables and its preparation method. The preparation method is a double-layer board structure formed by sintering a nanoporous structure material doped with nanothermal cables and multi-walled carbon nanotubes and a graphene material respectively. The present invention uses silver with a high interfacial compatibility with carbon nanotubes as the nanothermal cable core, avoiding the adverse consequences of no obvious improvement or even decrease in thermal conductivity caused by poor material compatibility, and supplements the porosity by compounding multi-walled carbon nanotubes to ensure the normal operation of the phase change liquid. Finally, the thermal conductivity of the board is further improved by pressing graphene.

Description

Technical Field

[0001] The present invention belongs to the field of thermally conductive inorganic materials, and particularly relates to a highly thermally conductive nanoporous cable structure board and a preparation method thereof. Background Art

[0002] With the large-scale development of large-scale integrated circuits and microelectronic packaging, electronic components have become increasingly miniaturized, and the heat dissipation problem has become an increasingly prominent issue that cannot be ignored. At present, the mainstream optimal solution to the heat dissipation problem is the heat pipe. A heat pipe is a heat dissipation component composed of two layers of porous structure boards with good thermal conductivity and a phase change liquid with good thermal conductivity. It is the general trend to seek heat pipe heat dissipation components with better thermal conductivity and lower stable temperature.

[0003] Graphene exists in nature and is the single-layer structure of graphite, with very good thermal conductivity. The thermal conductivity of pure and defect-free single-layer graphene is the best so far.

[0004] Carbon nanotubes are mainly composed of several to dozens of coaxial circular tubes formed by carbon atoms arranged in a hexagonal pattern. The distance between layers is fixed, and they can be regarded as coaxial rolled-up graphene. According to the different orientations of the carbon hexagons along the axial direction, they can be divided into three types: zigzag, armchair, and helical. Carbon nanotubes are an excellent one-dimensional thermally conductive nanomaterial, and there is a maximum value point with temperature change.

[0005] Metals generally have good thermal conductivity, and silver is the best thermally conductive metal. From a microscopic perspective, the carriers of solid heat transfer are phonons and free electrons. For metal solids, the number of free electrons is large, the mass is light, and the heat transfer speed is fast, which is the main mechanism of heat conduction. In semiconductor and insulator materials (such as carbon nanotubes), free electrons are few, and phonons are the main carriers of heat. Filling metal nanowires dominated by electron heat conduction into carbon nanotubes to form a carbon nanotube heat cable will greatly improve the thermal conductivity of the material. Summary of the Invention

[0006] Object of the Invention: The technical problem to be solved by the present invention is to further increase the upper limit of the heat conduction rate of the heat pipe and provide a highly thermally conductive nanoporous cable structure board and a preparation method thereof.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A highly thermally conductive nanoporous cable structure board is a double-layer board structure formed by sintering a nanoporous structure material doped with a nanoporous cable and multi-walled carbon nanotubes and a graphene material with a thickness ratio of 1-5:1-5; the nanoporous cable is a linear thermally conductive material with single-walled carbon nanotubes loaded with silver nanowires.

[0009] A preparation method of the above-mentioned barrier-pressed sintered porous structure board, the method comprising the following steps:

[0010] (1) Treating single-walled carbon nanotube materials by in-situ growth of silver nanowires to obtain nano-thermal cables;

[0011] (2) Mixing the nano-thermal cable materials with multi-walled carbon nanotube materials to form nano-thermal cable / carbon nanotube composites; (3) Taking one of the nano-thermal cable / carbon nanotube composites and graphene, dispersing it between two barrier plates, and preparing the first layer of board by pressing with a hydraulic press; after opening the mold, dispersing the other material on the first layer of board, and preparing a double-layer board by pressing with two barrier plates using a hydraulic press, and then annealing it in a cold water bath;

[0012] (4) Feeding the double-layer board annealed in step (3) into a sintering device for high-temperature sintering;

[0013] (5) Slowly releasing the pressure and then taking it out to obtain the product.

[0014] In the above preparation method, in step (1), the in-situ growth of silver nanowires requires a carbon nanotube surface modifier and a nanowire in-situ growth stock solution; for every 100 parts of carbon nanotube materials, 90-100 parts of surface modifier and 270-300 parts of nanowire in-situ growth solution are used.

[0015] In the above preparation method, in step (1), the silver nanowire growth environment is 50-70 °C.

[0016] In the above preparation method, in step (1), the surface modifier used is any one combination of strong oxidizing modifiers, carboxylic acid modifiers or plasma modifiers; further preferably: the surface modifier is 68 wt% concentrated nitric acid;

[0017] The nanowire in-situ growth solution is any one combination of 30-50 wt% silver nitrate solution and 30-50 wt% silver acetate solution.

[0018] In the above preparation method, in step (2), the dosage ratio of nano-thermal cable materials to multi-walled carbon nanotube materials is 1-10:1.

[0019] In the above preparation method, in step (3), the dosage ratio of nano-thermal cable / carbon nanotube composites to graphene materials is (85-95):(5-15).

[0020] In the above preparation method, in step (3), the barrier plate is any one of polytetrafluoroethylene, polyimide, polyethylene terephthalate, epoxy resin, and stainless steel plate.

[0021] In the above preparation method, in step (3), the temperature of the hydraulic press platen is 190 - 210 °C, the pressure is 10 - 20 MPa, and the platen time is 5 - 10 min.

[0022] In the above preparation method, in step (4), the annealed double-layer sheet is sent into a hot press furnace for sintering. The protective gas is any combination of argon or nitrogen, the pressure is 10 - 15 MPa, the temperature is 600 - 700 °C, and the sintering time is 4 - 8 h.

[0023] Preferably in step (3), the separator is polytetrafluoroethylene (PTFE) with a thickness of about 2 mm.

[0024] In the technical solution of the present invention: the pressure is gauge pressure.

[0025] Beneficial effects:

[0026] (1) Due to the special structure of its double-layer material in the present invention, the physical properties of graphene and nano-thermal cable materials are different. Coupled with the influence of the modification process on the porosity of carbon nanotubes, a double-layer porous structure will be formed. The pore structures of graphene and nano-thermal cables can also be regulated by placing them in a hot press furnace at different temperatures and pressures. By sintering in this way, a special perforated structure can also be formed, which is more beneficial for the working of the phase change liquid.

[0027] (2) The present invention uses silver with a high interfacial compatibility with carbon nanotubes as the core of the nano-thermal cable, avoiding the adverse consequences of no obvious improvement or even decrease in thermal conductivity caused by poor material compatibility, and supplementing the porosity through composite double-walled carbon nanotubes to ensure the normal working of the phase change liquid. Finally, the thermal conductivity of the sheet is further improved by pressing graphene.

[0028] (3) The porous structure sheet of the present invention has high strength and can be reused. Specific embodiments

[0029] The following further illustrates the present invention in conjunction with embodiments, but the protection scope of the present invention is not limited thereto:

[0030] The single-walled carbon nanotubes are products with the brand number FT2000 of Jiangsu Tiannai Technology Co., Ltd., and the graphene material is a product with the brand number XF001H of Jiangsu Xianfeng Nano Materials Technology Co., Ltd. The multi-walled carbon nanotubes are products of Jiangsu Xianfeng Nano Materials Technology Co., Ltd., with the serial number: XFQ047.

[0031] Example 1

[0032] (1) 100 parts of single-walled carbon nanotube material were subjected to surface oxidation treatment with 100 parts of 68 wt% concentrated nitric acid as a surface modifier, and then immersed in 280 parts of 40 wt% silver nitrate solution of nanowire in-situ growth liquid at 60° C. for 24 h, and then taken out to obtain a nano thermal cable material;

[0033] (2) Nano thermal cables (85 parts) and multi-walled carbon nanotubes (15 parts) were dispersed in a 1 wt% dilute nitric acid solution, heated to 60°C, stirred at 80 rpm, and then filtered and dried for 10 hours after sufficient stirring.

[0034] (3) Preheat the polytetrafluoroethylene (PTFE) plate with a release agent sprayed on both sides at 200°C for 5 minutes. Take 50g of the nanoheat cable / double-walled carbon nanotube mixed material and disperse it between two layers of polytetrafluoroethylene plates. Press it for 10 minutes at a hydraulic press temperature of 190°C and a pressure of 10MPa to a thickness of 2mm. After opening the mold, disperse 50g of graphene on the formed porous structure plate. Press it for 10 minutes at a hydraulic press temperature of 200°C and a pressure of 10MPa to obtain a graphene plate with a thickness of 2mm. After opening the mold, place it in a cold water bath for annealing. The entire process is carried out under the protection of an argon atmosphere.

[0035] (4) Place the doped nano thermal cable in a hot press furnace for sintering at 10 MPa and 650°C for 6 h to ensure complete sintering. Release the pressure at a rate of 0.5 MPa / s and then take it out to obtain the product.

[0036] Example 2

[0037] Except that the sintering conditions in step (4) are 11 MPa and 650° C., other conditions are the same as those in Example 1.

[0038] Example 3

[0039] Except that the sintering conditions in step (4) are 13 MPa and 650° C., other conditions are the same as those in Example 1.

[0040] Example 4

[0041] Except that the sintering conditions in step (4) are 15 MPa and 650° C., other conditions are the same as those in Example 1.

[0042] The thermal conductivity measurement method strictly complies with GB / T 10297-2015.

[0043] Porosity:

[0044] P: porosity of material, %; V0: volume of material in natural state; V: absolute dense volume of material.

[0045] Table 1

[0046] Thermal conductivity (W / m*K) Porosity % Example 1 1605.4 23 Example 2 1887.5 22 Example 3 2114.1 20 Example 4 1917.5 17

[0047] From the data in the table and the phenomena during the experiment, it is found that the porosity continuously decreases as the pressure of hot-pressing sintering increases, while the thermal conductivity shows an obvious extreme value. This may be because under the condition of this porosity, the interfacial compatibility of nano-thermal cables, multi-walled carbon nanotubes and graphene materials is better. It is speculated that under this condition, the thermal transport efficiency of phonons is greatly suppressed, the scattering of phonon electrons decreases, and the main heat transport is mainly through electron heat transport.

[0048] The present invention provides an idea and method for a porous structure plate of a high thermal conductivity nano-thermal cable and its preparation method. There are many methods and ways to specifically implement this technical solution. The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention. Each component not clearly defined in this embodiment can be realized by existing technologies.

Claims

1. A porous structure board of a high thermal conductivity nano thermal cable, characterized in that It is a double-layer plate structure formed by sintering a porous structural material of a nano-thermal cable / carbon nanotube composite material with a thickness ratio of 1-5:1-5 and a graphene material; the nano-thermal cable is a linear heat-conducting material with silver nanowires loaded on single-walled carbon nanotubes. The high thermal conductivity nano-thermal cable porous structural plate is prepared by the following method: (1) Treat the single-walled carbon nanotube material by in-situ growth of silver nanowires to obtain a nano-thermal cable; (2) Mix the nano-thermal cable with multi-walled carbon nanotubes to form a nano-thermal cable / carbon nanotube composite material; (3) Take one of the nano-thermal cable / carbon nanotube composite material and graphene, disperse it between two separator plates, and prepare the first layer of plate by pressing with a hydraulic press; after opening the mold, disperse the other material on the first layer of plate, and use two separator plates to press with a hydraulic press to obtain a double-layer plate, and then place it in a cold water bath for annealing treatment; (4) Send the double-layer plate annealed in step (3) into a sintering device for high-temperature sintering; Take it out after slowly releasing the pressure to obtain it; (5) In step (4), send the annealed double-layer plate into a hot pressing furnace for sintering, the protective gas is any one of argon or nitrogen, the pressure is 10-15 MPa, the temperature is 600-700 °C, and the sintering time is 4-8 h.

2. The highly thermally conductive nanoporous structure board of the nanothermal cable according to claim 1, wherein, In step (1), the in-situ growth of silver nanowires treatment requires a carbon nanotube surface modifier and a nanowire in-situ growth stock solution; for every 100 parts of the single-walled carbon nanotube material, 90-100 parts of the surface modifier and 270-300 parts of the nanowire in-situ growth solution are used.

3. The porous structure plate of the high thermal conductivity nano thermal cable according to claim 1, characterized in that In step (1), the growth environment of the silver nanowires is 50-70 °C.

4. The porous structure board of the high thermal conductivity nano thermal cable according to claim 1, characterized in that In step (1), the surface modifier used is any one of a strong oxidizing modifier, a carboxylic acid modifier or a plasma modifier; the nanowire in-situ growth solution is any one of a 30-50 wt% silver nitrate solution and a 30-50 wt% silver acetate solution.

5. The porous structural board of the high thermal conductivity nano thermal cable according to claim 4, characterized in that, The surface modifier is concentrated nitric acid.

6. The porous structure board of the high thermal conductivity nano thermal cable according to claim 1, characterized in that In step (2), the dosage ratio of the nano-thermal cable material to the multi-walled carbon nanotube material is 1-10:

1.

7. The porous structure board of the high thermal conductivity nano thermal cable according to claim 1, characterized in that, In step (3), the dosage ratio of the nano-thermal cable / carbon nanotube composite material to the graphene material is (85-95):(5-15).

8. The porous structural board of the high thermal conductivity nano thermal cable according to claim 1, characterized in that In step (3), the separator plate is any one of polytetrafluoroethylene, polyimide, polyethylene terephthalate, epoxy resin, and stainless steel plate.

9. The porous structure board of the high thermal conductivity nano thermal cable according to claim 1, wherein In step (3), the temperature used for pressing with the hydraulic press is 190-210 °C, the pressure is 10-20 MPa, and the pressing time is 5-10 min.