Vapor chamber based on high thermal conductivity aerogel / microgroove composite capillary core and preparation method

Abstract

The invention relates to a vapor chamber based on a high-heat-conduction aerogel / microgroove composite capillary wick and a preparation method thereof.The vapor chamber comprises a lower evaporation plate and an upper condensation plate, the lower evaporation plate and the upper condensation plate are connected in a sealed mode, a hollow cavity is formed in the lower evaporation plate, and a liquid injection opening communicated with the hollow cavity is formed in the side wall of the lower evaporation plate; the evaporation device further comprises four lateral convergence type micro-groove structures which are evenly distributed on the top face of the evaporation lower plate and communicated with the hollow cavity, a gap is formed between every two adjacent lateral convergence type micro-groove structures, every two adjacent lateral convergence type micro-groove structures are symmetrical along the gaps, and the lateral convergence type micro-groove structures are communicated with the hollow cavity. The four gaps are communicated with the center of the lower evaporation plate; the MXene-graphene aerogel capillary core plate is located on the lower evaporation plate, and the MXene-graphene aerogel capillary core plate and the lower evaporation plate are integrally formed. The invention also provides a preparation method of the vapor chamber. According to the vapor chamber, the temperature uniformity and the liquid return capacity of the vapor chamber are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of heat dissipation and cooling of high-power density microelectronic power devices, and particularly relates to a heat pipe with a high thermal conductivity aerogel / microchannel composite capillary core and a preparation method thereof. Background Art

[0002] With the development of the manufacturing process technology of microprocessors (CPUs, GPUs), the increase in the number of cores, and the emergence of new application scenarios such as AI and deep learning, the power and energy consumption of microprocessors have gradually increased, and the working temperature of microprocessors has increased synchronously. Therefore, the corresponding thermal management technology urgently needs to be developed. The heat pipe that operates by means of the latent heat of vaporization of the working fluid is particularly suitable for dissipating heat from heat sources with a small area and high power density. The passive heat dissipation heat pipe is combined with an active heat dissipation method, such as an air-cooled fin or a liquid-cooled water circuit board, so that the heat of the microprocessor with a small area can be uniformly transferred to the condensation end of the large-area heat pipe through the rapid longitudinal and transverse movement of the vapor in the vacuum environment, efficiently taking away the heat of the microprocessor while avoiding the generation of local hot spots, which is beneficial to the long-term high-power operation of the microprocessor.

[0003] Filling a working fluid with high surface tension and high latent heat of vaporization in an approximate vacuum environment is one of the cores of the heat pipe. Equally important is the capillary structure inside the heat pipe. A reasonable capillary core design should consider two aspects: heat diffusion and working fluid transportation. In terms of heat diffusion, the capillary core design enables heat to be evenly diffused from the heat source to the entire heat pipe and ensures the best liquid film meniscus inside the heat pipe to efficiently evaporate and provide capillary pressure. In terms of working fluid transportation, the capillary core design should enable the condensed working fluid to be quickly transported back to the center of the heat source. At present, most commercial heat pipes and their capillary cores are made of copper. For example, the three types of capillary structures, such as copper mesh, copper foam, and copper microchannels, often have great room for improvement in terms of heat diffusion and working fluid transportation, such as the liquid return ability. Therefore, it is of great significance to develop a heat pipe with a high thermal conductivity aerogel / microchannel composite capillary core and a preparation method thereof to improve the temperature uniformity and liquid return ability. Summary of the Invention

[0004] Aiming at the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a heat pipe with a high thermal conductivity aerogel / microchannel composite capillary core and a preparation method thereof, which improve the temperature uniformity and liquid return ability of the heat pipe.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions: A heat pipe with a high thermal conductivity aerogel / microchannel composite capillary core, including an evaporation lower plate and a condensation upper plate, the evaporation lower plate and the condensation upper plate are hermetically connected, the evaporation lower plate has a hollow cavity inside, and a liquid injection port communicating with the hollow cavity is opened on the side wall of the evaporation lower plate. It further includes:

[0006] Four lateral converging microgroove structures are provided, and the four lateral converging microgroove structures are evenly arranged on the top surface of the evaporation lower plate and are all communicated with the hollow cavity. There is a gap between every two adjacent lateral converging microgroove structures, and every two adjacent lateral converging microgroove structures are symmetric along the gap. The four gaps are all communicated with the center of the evaporation lower plate;

[0007] The MXene-graphene aerogel capillary core plate is located on the evaporation lower plate, and on the MXene-graphene aerogel capillary core plate, there are four MXene-graphene aerogel capillary cores adapted to the four lateral converging microgroove structures;

[0008] The four lateral converging microgroove structures are used to diffuse heat transversely, the four MXene-graphene aerogel capillary cores are used to diffuse heat longitudinally, and after the four MXene-graphene aerogel capillary cores and the four lateral converging microgroove structures cooperate, they are also used to make the working medium flow directionally.

[0009] Preferably, the four gaps coincide with the cross-shaped center line of the evaporation lower plate, and each lateral converging microgroove structure includes a plurality of microgrooves arranged parallel to each other and at equal intervals. The width of each microgroove is 1.5 mm, and the height of each microgroove is 1 mm.

[0010] Preferably, each microgroove forms an angle of 45° with the center line of the evaporation lower plate.

[0011] Preferably, the MXene-graphene aerogel capillary core plate is integrally formed with the evaporation lower plate through multiple support columns. The multiple support columns are arranged vertically on each gap. There are also a plurality of grooves adapted to the multiple support columns on the MXene-graphene aerogel capillary core plate (2). The multiple support columns are used to form mechanical support for the MXene-graphene aerogel capillary core in the height direction.

[0012] Preferably, the multiple support columns are evenly distributed on each gap. The distance between adjacent two support columns is 8.5 mm. The length of each support column is 1.5 mm - 1.8 mm, the width of each support column is 1.5 mm - 1.8 mm, the height of each support column is 2 mm, and the thickness of the MXene-graphene aerogel capillary core plate is 0.08 mm.

[0013] Preferably, a welding rod groove is provided at the edge of the top wall of the evaporation lower plate, and the condensation upper plate is welded to the evaporation lower plate through the welding rod in the welding rod groove.

[0014] Preferably, both the evaporation lower plate and the condensation upper plate are aluminum-based rectangular plates. The four lateral converging microgroove structures are arranged in pairs symmetrically, and the gap between every two lateral converging microgroove structures coincides with the cross-shaped center line of the evaporation lower plate.

[0015] The present invention provides a method for preparing a heat pipe based on a high thermal conductivity aerogel / microchannel composite capillary core, comprising the following steps:

[0016] Process four laterally converging microchannel structures on the top surface of the evaporation lower plate;

[0017] Integrally form an MXene-graphene aerogel capillary core plate on the evaporation lower plate processed with four laterally converging microchannel structures;

[0018] Then hermetically connect the condensation upper plate and the evaporation lower plate to obtain a heat pipe;

[0019] The processing steps for integrally forming the MXene-graphene aerogel capillary core plate on the evaporation lower plate are as follows:

[0020] Pour the prepared MXene-graphene solution onto the evaporation lower plate with four laterally converging microchannel structures, perform freeze-drying to obtain an MXene-graphene aerogel with a thermal conductivity of 25 W / m·K to 30 W / m·K; then perform integrally formed high-temperature calcination on the evaporation lower plate with the MXene-graphene aerogel.

[0021] Preferably, sputter a titanium layer on the four laterally converging microchannel structures, the thickness of the titanium layer is 40 mm to 50 mm, and the condensation upper plate covers the evaporation lower plate with the MXene-graphene aerogel for integrally formed high-temperature calcination and hermetic connection.

[0022] Preferably, the temperature of freeze-drying is -60 °C, the duration of freeze-drying is 12 h, and the high-temperature calcination is divided into three stages. The first-stage calcination is to increase the temperature from 25 °C to 80 °C at a heating rate of 2 °C / min and hold for 0.5 h; the second-stage calcination is to increase the temperature from 80 °C to 150 °C at a heating rate of 1 °C / min and hold for 1.0 h; the third stage is to increase the temperature from 150 °C to 300 °C at a heating rate of 0.5 °C / min and hold for 2 h.

[0023] Preferably, the MXene-graphene solution is prepared by the following method: Add 50 mg of multi-layer accordion-shaped MXene to 10 ml of an aqueous graphene oxide solution with a concentration of 10 mg / ml, mix and perform ultrasonic treatment for 10 min, then add 50 mg of L-cysteine and 100 mg of L-ascorbic acid, stir in an ice bath for 30 min under a helium atmosphere, and perform ultrasonic treatment for 10 min to obtain the MXene-graphene solution.

[0024] The present invention provides an application of a heat pipe based on an MXene-graphene aerogel / microchannel composite capillary core in aerospace heat dissipation.

[0025] Compared with the prior art, the beneficial effects of the present invention:

[0026] The present invention designs a heat pipe based on a high - thermal - conductivity aerogel / micro - groove composite capillary wick, which solves the problems of poor temperature uniformity and liquid return ability of the original copper heat pipe.

[0027] This is because the evaporation lower plate forms four lateral - convergence micro - groove structures through mechanical finishing. The four lateral - convergence micro - groove structures can quickly introduce the condensed working fluid to the heat source through their high permeability, keep the liquid film at the heat source uninterrupted, prevent the heat source from drying out, improve the liquid return ability, and can cool the micro - processor. At the same time, due to the special design structure of the lateral - convergence micro - groove, it can be seen that heat uniformly diffuses laterally in the evaporation lower plate from the central heat source, which is beneficial to reducing the diffusion thermal resistance of the heat pipe. The MXene - graphene aerogel capillary wick in the MXene - graphene aerogel capillary wick plate has a certain thermal conductivity. Especially in the direction perpendicular to the heat source, it is beneficial to direct the heat to the evaporation liquid film interface for longitudinal diffusion (in particular, the MXene - graphene aerogel capillary wick is combined with the evaporation lower plate through a titanium - plating layer, and the contact thermal resistance can be ignored), reducing the evaporation thermal resistance of the heat pipe and improving the liquid return ability.

[0028] The MXene - graphene aerogel capillary wick in the MXene - graphene aerogel capillary wick plate has an extremely high capillary pressure due to the special two - dimensional sheet - like structure of Mxene and graphene, high electron and phonon mobility, honeycomb structure prepared by directional freeze - drying technology, lattice defect repair between Mxene and graphene promoted by high - temperature calcination during the preparation process, inherent micron - scale pores of the aerogel, porosity above 98%, and hydrophilic characteristics of the Mxene material. Therefore, the combination of the MXene - graphene aerogel capillary wick and the lateral - convergence micro - groove structure, with the directional heat transfer channel, high permeability, and large capillary pressure, can reduce the overall thermal resistance of the heat pipe and improve its temperature uniformity.

[0029] Compared with traditional metal capillary wicks (such as sintered copper), the MXene - graphene aerogel capillary wick plate of the present invention has an extremely low density (about 15,000 g / m 3 ³), significantly reducing the weight of the heat pipe and providing an effective technical guarantee for lightweight design. By using this MXene - graphene aerogel capillary wick plate, the heat pipe not only improves the heat transfer efficiency, but also realizes a more uniform temperature distribution and a faster working fluid circulation, and is particularly suitable for heat dissipation applications with high heat - flux density and lightweight requirements.

[0030] Both the evaporation lower plate and the condensation upper plate provided by the present invention are aluminum-based rectangular plates. By introducing MXene-graphene aerogel on the evaporation lower plate and the condensation upper plate, the problem that aluminum is prone to oxidation and it is impossible to process capillary structures by sintering aluminum foam on aluminum plates is overcome. A porous structure is realized on the aluminum heat pipe, and the porous MXene-graphene aerogel cooperates with the lateral converging microgroove structure to achieve directional and rapid liquid return, thereby realizing isothermal performance under high heat flux density. At the same time, the titanium plating layer also solves the problem that the aluminum-based heat pipe is prone to corrosion.

[0031] Finally, compared with traditional metal capillary cores (such as sintered copper), the aerogel capillary core has an extremely low density (about 15,000 g / m 3 ), significantly reducing the weight of the heat pipe. In addition, both the evaporation lower plate and the condensation upper plate are made of aluminum, which also reduces the weight, providing an effective technical guarantee for lightweight design. By adopting this composite aerogel capillary core structure, the heat pipe not only improves the heat transfer efficiency, but also achieves a more uniform temperature distribution and a faster working fluid circulation, and is particularly suitable for heat dissipation applications with high heat flux density and lightweight requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1-1 It is a schematic three-dimensional structure sectional view of the present invention.

[0033] Figure 1-2 It is an exploded view of the three-dimensional structure of the present invention.

[0034] Figure 2-1 It is a three-dimensional view of the evaporation lower plate of the present invention.

[0035] Figure 2-2 It is a front view of the evaporation lower plate of the present invention.

[0036] Figure 2-3 It is a top view of the evaporation lower plate of the present invention.

[0037] Figure 2-4 It is a sectional view of the evaporation lower plate of the present invention.

[0038] Figure 3-1 It is a three-dimensional view of the MXene-graphene aerogel capillary core of the present invention.

[0039] Figure 3-2 It is a front view of the MXene-graphene aerogel capillary core of the present invention.

[0040] Figure 4-1 It is a three-dimensional view of the condensation upper plate of the present invention.

[0041] Figure 4-2 It is a front view of the condensation upper plate of the present invention.

[0042] Figure 4-3 It is a top view of the condensation upper plate of the present invention.

[0043] Reference numerals

[0044] 1. Evaporation lower plate; 1.1 Titanium plating layer; 1.2 Support column; 1.3 Electrode slot; 1.4 Lateral converging microgroove structure; 1.5 Liquid injection port; 2. MXene-graphene aerogel wick; 3. Condensation upper plate. Detailed implementation manners

[0045] The following will describe in detail the specific implementation manners of the present invention. However, it should be understood that the protection scope of the present invention is not limited by the specific implementation manners. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention. The experimental methods described in the embodiments of the present invention are all conventional methods unless otherwise specified.

[0046] The inventors found that in the current preparation of aluminum-based heat pipes, due to the easy oxidation property of aluminum, microgrooves are mostly formed by machining. Therefore, due to the lack of certain capillary pressure, the temperature uniformity of aluminum-based heat pipes is often poor under high heat flux density. On the other hand, porous Mxene-graphene composite aerogel has a customizable porous structure and certain good thermal conductivity. This means that the aerogel can provide good capillary pressure and a fast heat flux transfer channel, while currently, Mxene-graphene composite aerogel has not been applied in heat pipes.

[0047] In view of this, the present invention provides a heat pipe based on a high thermal conductivity aerogel / microgroove composite wick and a preparation method thereof to overcome the problems existing in the prior art. In the present invention, the longitudinal inherent high thermal conductivity of MXene-graphene aerogel can quickly conduct heat vertically from the heat source to the liquid film interface, maintaining the optimal curvature radius of the liquid film interface, which is beneficial to liquid film evaporation and maintaining the maximum capillary pressure; the aluminum-based lateral converging microgrooves formed by machining can quickly spread heat horizontally from the heat source due to their distribution and the high thermal conductivity of aluminum, making the entire liquid film uniformly heated and avoiding local hot spots. The combination of the two reduces the evaporation thermal resistance and diffusion thermal resistance of the heat pipe, which is beneficial to its temperature uniformity. In particular, in the present invention, there is a nanoscale titanium plating layer between the MXene-graphene aerogel and each lateral converging microgroove structure, which reduces the contact thermal resistance between the aerogel and each lateral converging microgroove structure through chemical bonding. Secondly, the high thermal conductivity aerogel / microgroove composite wick in the present invention has both the large capillary pressure brought by the high porosity and hydrophilic aerogel and the high permeability brought by the millimeter-scale microgrooves, so that during the operation of the working fluid in the heat pipe, the working fluid can be smoothly transported to the center of the heat source to complete an efficient cycle. In addition, the light weight of the aerogel and the light weight of aluminum endow the overall heat pipe with extremely light weight, which is beneficial to the use of the heat pipe in specific occasions.

[0048] As shown in the attachedFigure 1-1 ~Attached Figure 4-3 As shown, the present invention provides a heat pipe with a high - thermal - conductivity aerogel / micro - groove composite wick, including an evaporation lower plate 1 and a condensation upper plate 3. The evaporation lower plate 1 and the condensation upper plate 3 are hermetically connected. The evaporation lower plate 1 has a hollow cavity inside, and a liquid injection port 1.5 communicating with the hollow cavity is provided on the side wall of the evaporation lower plate 1. It further includes: a lateral - convergence micro - groove structure 1.4 and an MXene - graphene aerogel wick plate 2, where

[0049] The lateral - convergence micro - groove structure 1.4 is provided with four, and the four lateral - convergence micro - groove structures 1.4 are evenly arranged on the top surface of the evaporation lower plate 1 and are all communicated with the hollow cavity. There is a gap between every two adjacent lateral - convergence micro - groove structures 1.4, and every two adjacent lateral - convergence micro - groove structures 1.4 are symmetric along the gap. The four gaps are all communicated with the center of the evaporation lower plate 1;

[0050] The MXene - graphene aerogel wick plate 2 is located on the evaporation lower plate 1, and the MXene - graphene aerogel wick plate 2 has four MXene - graphene aerogel wicks adapted to the four lateral - convergence micro - groove structures 1.4.

[0051] Based on the principles of the high - thermal - conductivity structure of MXene and graphene, the formation of a vertical - thermal - conductivity honeycomb structure by directional freezing to control ice crystal growth, the processing of a longitudinal - thermal - conductivity network by lateral convergence, the high capillary pressure of the aerogel on the working fluid, and the high permeability of the aluminum - based micro - groove, the present invention proposes a heat pipe with a high - thermal - conductivity aerogel / micro - groove composite wick. After the evaporation lower plate 1 receives heat from the heat source, the heat will be transferred along the lateral - convergence micro - groove structure 1.4 and in the direction of the MXene - graphene aerogel. This heat - transfer design enables the liquid film formed by the liquid working fluid (deionized water) in the MXene - graphene aerogel wick plate 2 to be uniformly heated while maintaining the optimal meniscus.

[0052] That is, when a small-volume heat source with a high heat flux density is combined with the evaporation lower plate 1 at the bottom of the heat pipe, the evaporation lower plate 1 contacts the heat from the heat source at the center, and the heat will be dissipated along two directions. One dissipation direction is that the lateral converging microchannel structure 1.4 evenly dissipates the heat from the center of the evaporation lower plate 1 to the surroundings; the other dissipation direction is that the MXene-graphene aerogel in the MXene-graphene aerogel wick plate 2 transfers the heat from the evaporation lower plate 1, passes through the titanium plating layer 1.1, and vertically to the working fluid (water) liquid film interface. The lateral heat diffusion enables uniform heat transfer between the entire evaporation lower plate 1 and the working fluid liquid film, avoiding the formation of local hot spots at the center due to insufficient liquid replenishment capacity under high power density; the longitudinal heat diffusion enables the center of the liquid film meniscus corresponding to the heat source to always maintain a certain curvature, thus maintaining efficient liquid film evaporation and capillary liquid absorption capacity; the combination of the two enables the working fluid to evaporate quickly and evenly and move to the condensation upper plate 3. In addition, the MXene-graphene aerogel in the MXene-graphene aerogel wick plate 2 has a high porosity, and the high porosity cooperates with the high permeability of the lateral converging microchannel structure 1.4 to directionally transport the condensed liquid working fluid from the condensation upper plate 3 back to the center of the heat source to complete the next working fluid heat transfer cycle.

[0053] There are four reasons for the high thermal conductivity of the MXene-graphene aerogel wick in the MXene-graphene aerogel wick plate 2: (1) One of the constituent materials, MXene, has a highly ordered and closely spaced layered structure, with a short heat conduction path. The strong metal bond between titanium and carbon atoms in MXene contributes to heat conduction; (2) One of the constituent materials, graphene, has a flaky structure, with extremely strong free electron migration ability, and the sp 2The hybrid bonds are extremely strong and can effectively transfer heat. The aerogel formed after the two are directionally freeze-dried forms a highly dense vertical honeycomb network structure, which can longitudinally transfer heat. After the aerogel is calcined at 300 °C, the defects of MXene and graphene are reduced, and the crystal structure is optimized, improving its internal heat conduction path. (3) There is a titanium coating between the composite aerogel and the aluminum-based microgrooves. Through calcination at 300 °C, the titanium coating can bond with the carbon in MXene and graphene (mainly the activated carbon atoms in MXene) to generate Ti-C bonds. The tight bonding and the high bonding area brought by the microgrooves reduce the contact thermal resistance between the evaporation bottom plate and the capillary wick. The high thermal conductivity of the above-mentioned aerogel and the tight combination of the aerogel and the evaporation bottom plate enable the evaporation bottom plate with aluminum-based microgrooves to quickly transfer heat to the surroundings after receiving heat from the heat source when the aerogel is used as the capillary wick (the aerogel transfers heat efficiently longitudinally, and the aluminum-based microgrooves transfer heat efficiently laterally), greatly reducing the overall thermal resistance of the heat pipe and improving the temperature uniformity. The inherently high porosity and uniformly distributed pore structure of the MXene-graphene aerogel enable the capillary wick to have a large capillary pressure. Combined with the high permeability of the lateral converging microgrooves of the evaporation bottom plate, the condensed working fluid can be directionally transferred to the heat source area, avoiding flow dead zones and ensuring the efficient operation of the heat pipe. (4) The hydrophilic groups on MXene are beneficial to the wetting of the working fluid and also contribute to the large capillary pressure of the capillary wick. On the other hand, the unique low density of the aerogel (the low density is 15000 g / m 3 ), combined with the aluminum material, makes the overall weight of the heat pipe small. The lightweight characteristic is beneficial to applications in specific scenarios, such as the aerospace field. The condensation top plate is made of aluminum alloy, the same as the evaporation bottom plate.

[0054] Specifically, as Figure 1-2 and Figure 2-1 shown, the four gaps coincide with the cross-shaped center line of the evaporation bottom plate 1.

[0055] Specifically, each lateral converging microgroove structure 1.4 includes a plurality of microgrooves arranged parallel to each other and at equal intervals. Both ends of the plurality of microgrooves are communicated with the gaps on both sides. The width of each microgroove is 1.5 mm, and the height of each microgroove is 1 mm. The width of the microgroove is determined after considering the viscosity of the aerogel precursor solution. For too narrow microgrooves, the aerogel solution cannot flow, and for too wide microgrooves, there is no capillary force and they cannot absorb water.

[0056] Specifically, each microgroove forms a 45° angle with the center line of the evaporation bottom plate 1. The reason for setting it at 45 degrees is to form lateral converging microgrooves around to guide the heat source. Otherwise, at high heat flux densities, the heat source will dry out due to the lack of working fluid reflux and form hot spots.

[0057] Specifically, the MXene-graphene aerogel capillary core plate 2 is integrally formed with the evaporation lower plate 1 through multiple support columns 1.2. The multiple support columns 1.2 are arranged vertically on each gap. The MXene-graphene aerogel capillary core plate 2 also has grooves adapted to the multiple support columns 1.2. The multiple support columns 1.2 are used to form mechanical support for the MXene-graphene aerogel capillary core 2 in the height direction.

[0058] The multiple support columns 1.2 and the multiple grooves can ensure that the heat pipe will not be deformed due to internal and / or external pressure during operation. A liquid injection pipe is connected to the liquid injection port 1.5. The length of the liquid injection pipe 1.5 can be arbitrary and can be selected as 20 mm. The liquid injection pipe is evacuated first and then the working fluid is transported.

[0059] Specifically, the multiple support columns 1.2 are evenly distributed on each gap. The distance between two adjacent support columns 1.2 is 8.5 mm. The length of each support column 1.2 is 1.5 mm to 1.8 mm, the width of each support column 1.2 is 1.5 mm to 1.8 mm, and the height of each support column 1.2 is 2 mm. The height of the MXene-graphene aerogel capillary core plate 2 is 0.08 mm.

[0060] If the height of the MXene-graphene aerogel capillary core plate 2 is too low, the overall liquid storage capacity is small, and local dry-out will occur under high heat flux density, which is not conducive to temperature uniformity. If the height of the MXene-graphene aerogel capillary core plate 2 is too high, the overall heat pipe will be too thick, and it is difficult to be excited under low flow density, resulting in too high thermal resistance. Selecting a thickness of 0.08 mm for the MXene-graphene aerogel capillary core plate 2 can just cooperate with the laterally converging microgroove structure 1.4.

[0061] The limitation of the length, width and height of each support column 1.2 here is the result after considering the steam pressure drop, in order to reduce the flow resistance between the steam and the main body. The fixed length is to closely fit the evaporation lower plate 1 and the condensation upper plate 3, both of which are aluminum plates.

[0062] Specifically, a welding rod groove 1.3 is provided at the edge of the top wall of the evaporation lower plate 1. The condensation upper plate 3 and the evaporation lower plate 1 are welded by welding rods in the welding rod groove 1.3, so that the MXene-graphene aerogel capillary core 2 forms mechanical support with the evaporation lower plate 1 in the height direction, and it can ensure that the heat pipe will not be deformed due to internal and / or external pressure during operation.

[0063] The evaporation lower plate 1 and the condensation upper plate 3 are both aluminum-based rectangular plates. The size of the evaporation lower plate 1 is l1×l2×h1, with a length of l1 = 78 mm, a width of l2 = 78 mm, and an overall height of h1 = 2.5 mm. There is a cavity inside the evaporation lower plate for carrying microchannels and support columns, with a size of l3×l4×h2, a length of l3 = 70 mm, a width of l4 = 70 mm, and an overall height of h2 = 2 mm. A 50-nm-thick titanium layer is deposited on the evaporation lower plate by magnetron sputtering. There are 12 support columns arranged in a cross shape and evenly distributed inside the evaporation lower plate. The size of a single support column is w1×w2×h3, with a length of w1 = 1.5 mm, a width of w2 = 1.5 mm, and an overall height of h3 = 2 mm. The distance between each two support columns is w3 = 8.5 mm. Welding rod grooves are machined around the evaporation lower plate. The size of the welding rod groove is l5×l6×l7×l8×w4×h4, with an outer frame length of l5 = 76 mm, an outer frame width of l6 = 76 mm, an inner frame length of l7 = 72 mm, an inner frame width of l8 = 72 mm, an overall width of w4 = 2 mm, and an overall height of h4 = 0.15 mm. There are microchannels arranged in a lateral convergence pattern inside the evaporation lower plate. The size of the microchannel is w5×r1×h5, with a width of w5 = 1.5 mm, an angle along the horizontal (vertical) central axis of r1 = 45°, and an overall height of h5 = 1 mm. The size of the liquid injection port is d1×d2×h6, with an outer diameter of d1 = 2 mm, an inner diameter of d2 = 1.5 mm, and an overall height of h6 = 20 mm. The size of the condensation upper plate is l9×l 10 ×h8, with a length of l9 = 78 mm and a width of l 10 = 78 mm, and an overall height of h8 = 0.5.

[0064] The purpose of giving the above dimensions is to control the overall thickness of the aluminum-based heat pipe within a certain range. The overall heat pipe should not be too thick, which can reduce the weight and make it more practical. Because in order to be applied in compact high heat flux power devices, if it is made too thick, it cannot be put in.

[0065] The evaporation lower plate 1 and the condensation upper plate 3 are both aluminum-based rectangular plates. The four lateral convergence microchannel structures 1.4 are symmetrically arranged in pairs, and the gap between each two lateral convergence microchannel structures 1.4 coincides with the cross-shaped center line of the evaporation lower plate 1.

[0066] By introducing MXene-graphene aerogel on the evaporation lower plate 1 and the condensation upper plate 3, the problem that aluminum is prone to oxidation and capillary structures cannot be processed by sintering foamed aluminum on the aluminum plate is overcome. A porous structure is realized on the aluminum heat pipe. The porous MXene-graphene aerogel cooperates with the lateral convergence microchannel structure to achieve directional and rapid liquid return, thereby realizing isothermal performance under high heat flux. At the same time, the titanium coating also solves the problem of easy corrosion of the aluminum-based heat pipe.

[0067] A heat pipe based on a high - thermal - conductivity aerogel / micro - groove composite capillary core and a preparation method thereof, comprising the following steps:

[0068] Process four lateral - convergence micro - groove structures 1.4 on the top surface of the evaporation lower plate 1;

[0069] Integrally form an MXene - graphene aerogel capillary core plate 2 on the evaporation lower plate 1 with four lateral - convergence micro - groove structures 1.4;

[0070] Then hermetically connect the condensation upper plate 3 and the evaporation lower plate 1 to obtain the heat pipe;

[0071] The processing steps for integrally forming the MXene - graphene aerogel capillary core plate 2 on the evaporation lower plate 1 are as follows:

[0072] Pour the prepared MXene - graphene solution onto the evaporation lower plate 1 with four lateral - convergence micro - groove structures 1.4, perform freeze - drying to obtain MXene - graphene aerogel with a thermal conductivity of 28 W / m·K; then perform integral high - temperature calcination on the evaporation lower plate 1 with MXene - graphene aerogel.

[0073] The processing steps for integrally forming the MXene - graphene aerogel capillary core plate 2 on the evaporation lower plate 1 are as follows:

[0074] Pour the prepared MXene - graphene solution onto the evaporation lower plate 1 with four lateral - convergence micro - groove structures 1.4, perform freeze - drying to obtain MXene - graphene aerogel with a thermal conductivity of 25 W / m·K; then perform integral high - temperature calcination on the evaporation lower plate 1 with MXene - graphene aerogel.

[0075] The processing steps for integrally forming the MXene - graphene aerogel capillary core plate 2 on the evaporation lower plate 1 are as follows:

[0076] Pour the prepared MXene - graphene solution onto the evaporation lower plate 1 with four lateral - convergence micro - groove structures 1.4, perform freeze - drying to obtain MXene - graphene aerogel with a thermal conductivity of 30 W / m·K; then perform integral high - temperature calcination on the evaporation lower plate 1 with MXene - graphene aerogel.

[0077] Specifically, sputter a titanium layer on the four lateral - convergence micro - groove structures 1.4, the thickness of the titanium layer is 40 mm - 50 mm, the condensation upper plate 3 covers the evaporation lower plate 1 with MXene - graphene aerogel for integral high - temperature calcination and hermetic connection, and the thickness of the titanium layer of 40 mm - 50 mm mainly solves the problem of easy corrosion of the aluminum - based heat pipe.

[0078] Specifically, the freeze-drying temperature is -60°C, and the freeze-drying duration is 12 h. The high-temperature calcination is divided into three stages. In the first stage of calcination, the temperature is raised from 25°C to 80°C at a heating rate of 2°C / min and held for 0.5 h. In the second stage of calcination, the temperature is raised from 80°C to 150°C at a heating rate of 1°C / min and held for 1.0 h. In the third stage, the temperature is raised from 150°C to 300°C at a heating rate of 0.5°C / min and held for 2 h.

[0079] The control of the calcination duration and rate is to protect the mechanical properties of the aerogel, making it have a certain elasticity. Secondly, it is to repair the lattice of MXene-graphene in the aerogel to improve the thermal conductivity, thereby facilitating the reduction of the overall thermal resistance of the heat pipe and the improvement of the temperature uniformity. The duration and rate of freeze-drying are meaningless. What matters is to form a vertical honeycomb structure by directional freezing to separate heat directionally and improve the temperature uniformity of the heat pipe.

[0080] Specifically, the MXene-graphene solution is prepared by the following method: 50 mg of multi-layer accordion-shaped MXene is added to a graphene oxide solution with a volume of 10 ml and a concentration of 10 mg / ml. After mixing, it is ultrasonically treated for 10 min. Then, 50 mg of L-cysteine and 100 mg of L-ascorbic acid are added, and it is stirred in an ice bath for 30 min under a helium atmosphere. After ultrasonically treating for 10 min, the MXene-graphene solution is obtained.

[0081] An application of a heat pipe based on an MXene-graphene aerogel / microchannel composite wick in aerospace heat dissipation.

[0083] The present invention discloses a heat pipe based on a high-thermal-conductivity aerogel / microchannel composite wick, which mainly includes an evaporation lower plate 1, an MXene-graphene aerogel wick plate 2, and a condensation upper plate 3. It is made by using precision machining, magnetron sputtering coating technology, directional freeze-drying technology, brazing technology, and cold welding technology.

[0084] Among them, support columns 1.2, electrode bar grooves 1.3, laterally converging microgroove structures 1.4, and liquid injection pipes 1.5 are processed on the evaporation lower plate 1, and a titanium layer 1.1 is completed on the evaporation lower plate 1 through a magnetron sputtering coating machine. Through the directional freeze-drying technology, a multi-layer accordion-shaped Mxene and graphene oxide GO solution are used to fabricate the MXene-graphene aerogel. Then, through the brazing technology, the evaporation lower plate 1, the MXene-graphene aerogel, and the condensation upper plate 3 are integrally integrated, so that the MXene-graphene aerogel is used to prepare the MXene-graphene aerogel capillary core plate 2; the VC vacuum liquid injection system is connected to the liquid injection pipe 1.5 for vacuum treatment and liquid injection, and the liquid injection port 1.5 is sealed through the cold welding technology, thereby completing the preparation of the aluminum-based heat pipe with the MXene-graphene aerogel / microgroove composite directional heat-conducting capillary core. The purpose of sealing the liquid injection port 1.5 through the cold welding technology is to prevent the overall temperature of the aluminum-based heat pipe from being too high and causing irreversible deformation.

[0085] Working principle:

[0086] During the entire operation process, the heat source transfers heat to the evaporation lower plate 1. On the one hand, due to the vertical honeycomb structure, the MXene-graphene aerogel on the evaporation lower plate 1 can directionally transfer heat to the liquid film meniscus through the titanium coating layer, enabling the meniscus to maintain the optimal curvature and promoting the rapid evaporation and rapid liquid return of the working fluid. On the other hand, the microgroove structure 1.3 with a laterally converging structure directionally diffuses the heat, making the entire liquid film interface uniformly heated and avoiding dry-out caused by heat accumulation in the center. In this way, the working fluid will efficiently heat up and evaporate and move to the condensation upper plate 3. After the working fluid condenses, it falls back to the MXene-graphene aerogel capillary core plate 2 by gravity. Due to the cooperation of the microgroove structure 1.3 with a laterally converging structure and the high permeability and high capillary pressure of the MXene-graphene aerogel capillary core plate 2, the working fluid will quickly converge to the center of the condensation upper plate 3 to complete the next cycle.

[0087] The design of the directional heat and the working fluid circulation loop ensures the uniform and rapid diffusion of heat, ensuring the rapid evaporation and latent heat release of the working fluid in the capillary core of the MXene-graphene aerogel capillary core plate 2 and the directional and rapid transportation. The overall heat pipe has excellent temperature uniformity while maintaining a low thermal resistance. The present invention has the advantages of good temperature uniformity and high thermal conductivity, and can be used to meet the heat dissipation requirements of microprocessors with high heat flux density and the requirements of lightweight devices.

[0088] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these changes and modifications.

Claims

1. A heat spreader based on a high thermal conductivity aerogel / microgroove composite capillary wick, characterized in that: The invention comprises an evaporation lower plate (1) and a condensation upper plate (3), wherein the evaporation lower plate (1) and the condensation upper plate (3) are sealed and connected, wherein the evaporation lower plate (1) has a hollow cavity inside, and a liquid injection port (1.5) connected to the hollow cavity is provided on the side wall of the evaporation lower plate (1), and further comprises: The lateral convergence type micro-groove structures (1.4) are arranged in four, and the four lateral convergence type micro-groove structures (1.4) are evenly arranged on the top surface of the evaporation lower plate (1) and are all connected to the hollow cavity, there is a gap between every two adjacent lateral convergence type micro-groove structures (1.4), and every two adjacent lateral convergence type micro-groove structures (1.4) are symmetrical along the gap, and the four gaps are all connected to the center of the evaporation lower plate (1); A MXene-graphene aerogel capillary core plate (2) is located on the evaporation lower plate (1), and the MXene-graphene aerogel capillary core plate (2) is integrally formed on the evaporation lower plate (1), and the MXene-graphene aerogel capillary core plate (2) has four MXene-graphene aerogel capillary cores that are compatible with the four lateral convergent microgroove structures (1.4).

2. The heat spreader based on high thermal conductivity aerogel / microgroove composite capillary wick according to claim 1, characterized in that: The four gaps coincide with the cross center line of the evaporation lower plate (1).

3. The heat spreader based on high thermal conductivity aerogel / microgroove composite capillary wick according to claim 2, characterized in that: Each lateral convergence type microgroove structure (1.4) comprises a plurality of microgrooves which are parallel to each other and arranged at equal intervals, and both ends of the plurality of microgrooves are connected to the gaps on both sides.

4. The heat spreader based on high thermal conductivity aerogel / microgroove composite capillary wick according to claim 3, characterized in that: Each micro groove forms an angle of 45° with the center line of the evaporation lower plate (1).

5. The heat spreader based on high thermal conductivity aerogel / microgroove composite capillary wick according to claim 1, characterized in that: The MXene-graphene aerogel capillary core plate (2) is integrally formed with the evaporation lower plate (1) via a plurality of support columns (1.2); the plurality of support columns (1.2) are vertically arranged on each gap; the MXene-graphene aerogel capillary core plate (2) also has a plurality of grooves adapted to the plurality of support columns (1.2); the plurality of support columns (1.2) are used to form mechanical support for the MXene-graphene aerogel capillary core (2) along a height direction.

6. The heat spreader based on high thermal conductivity aerogel / microgroove composite capillary wick according to claim 5, characterized in that: A plurality of support columns (1.2) are evenly distributed in each gap, and the distance between two adjacent support columns (1.2) is 8.5 mm, the height of each support column (1.2) is 2 mm, and the thickness of the MXene-graphene aerogel capillary core plate (2) is 0.08 mm.

7. The heat spreader based on high thermal conductivity aerogel / microgroove composite capillary wick according to claim 1, characterized in that: A welding rod groove (1.3) is provided at the edge of the top wall of the evaporation lower plate (1), and the condensation upper plate (3) and the evaporation lower plate (1) are welded via welding rods in the welding rod groove (1.3).

8. The heat spreader based on high thermal conductivity aerogel / microgroove composite capillary wick according to claim 2, characterized in that: The evaporation lower plate (1) and the condensation upper plate (3) are both aluminum-based rectangular plates, the four lateral convergence type micro-groove structures (1.4) are symmetrically arranged in pairs, and the gap between each two lateral convergence type micro-groove structures (1.4) coincides with the cross center line of the evaporation lower plate (1).

9. The method for preparing a heat spreader based on a high thermal conductivity aerogel / microgroove composite capillary wick according to claim 1, characterized in that: The steps include: Four lateral convergent micro-groove structures (1.4) are processed on the top surface of the evaporation lower plate (1); A MXene-graphene aerogel capillary core plate (2) is integrally formed on an evaporation lower plate (1) having four lateral convergent microgroove structures (1.4); Then the condensation upper plate (3) and the evaporation lower plate (1) are sealed and connected to obtain a heat diffusion plate; The processing steps of forming the MXene-graphene aerogel capillary core plate (2) integrally with the evaporation lower plate (1) are as follows: The prepared MXene-graphene solution is poured onto an evaporation lower plate (1) having four lateral convergent microgroove structures (1.4), and freeze-dried to obtain a MXene-graphene aerogel having a thermal conductivity of 25 W / m·K to 30 W / m·K; and the evaporation lower plate (1) having the MXene-graphene aerogel is integrally formed and calcined at high temperature.

10. The method for preparing a heat spreader based on a high thermal conductivity aerogel / microgroove composite capillary wick according to claim 9, characterized in that: A titanium layer is sputtered on the four lateral convergent microgroove structures (1.4), the thickness of the titanium layer being 40 mm to 50 mm, and the condensation upper plate (3) is covered on the evaporation lower plate (1) having the MXene-graphene aerogel to be integrally formed and high-temperature calcined for sealing connection.

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