A method for preparing a capillary wick with controllable internal microenvironment

Abstract

The present invention discloses a method for preparing a capillary wick with a controllable internal microenvironment, and belongs to the field of thermal management technology. The method comprises: selecting raw material powder; preparing a blank by a selective laser sintering process, and then subjecting the blank to A heat treatment to obtain a capillary wick with a controllable internal microenvironment. The present invention obtains a capillary wick with a controllable internal microenvironment by controlling the composition of the raw materials, especially introducing additives of appropriate components and amounts, controlling the scanning interval under low-power and high-speed scanning conditions, and combining A heat treatment in a hydrogen-containing atmosphere. The raw materials selected in the present invention are reasonable, the preparation process is simple and controllable, the internal microenvironment of the obtained product is controllable and stable, the obtained product has superior performance, and is convenient for large-scale industrial application.

Description

Technical Field

[0001] The invention discloses a method for preparing a capillary wick with controllable internal microenvironment, and belongs to the technical field of thermal management. Background Art

[0002] For electronic chips, the integrated functions are gradually increasing and high-throughput, resulting in high integration, small size, and high heat consumption. A large amount of heat is generated in an extremely small volume, which puts higher requirements on the thermal management technology of electronic equipment. If the heat dissipation problem is not handled properly, it will cause the electronic equipment to freeze, run programs slowly, burn out the motherboard, and even cause the risk of explosion. Solving the safe and efficient heat dissipation technology of electronic equipment in a small space is of great significance to the development of electronic information technology, and can effectively promote the rapid development of cloud computing, big data, mobile communications and other fields.

[0003] As a device that uses the phase change principle to dissipate heat, the heat spreader has strong comprehensive heat transfer performance. The capillary wick of a conventional heat spreader is a conventional linear or planar structure composed of grooves, meshes, wires, powders, etc., which is made by machining or pressing and sintering. The processing steps are numerous, the process is complex, and the process parameters are numerous, and each link needs to be strictly controlled. The structure around the heat source is the same, and the capillary function obtained is single and the performance needs to be further improved. For example, patent CN110769647A introduces a screen printing preparation process for a heat spreader, which includes the following steps: slurry preparation, printing, degumming and curing, sintering, etc. This type of screen printing is first difficult to produce a product with a controllable internal microenvironment; second, the process is complex, and the performance of the prepared product is too volatile. For example, patent TWM413159U involves a heat spreader with a support structure. It introduces that "to achieve the above-mentioned purpose, the present invention is a heat spreader with a support structure, which is used for heat dissipation of electronic components. It has a first and a second plate connected to form a closed cavity, and the cavity is filled with fluid. The inner surface of the first plate and the inner wall of the second plate are sprayed with metal copper powder using high-pressure air, so that they are respectively coated with a layer of metal film. The metal film layer is further sintered to form a capillary structure, and the fluid arranged in the cavity and a plurality of porous support structures formed by extrusion and sintering of copper metal powder metallurgy are used to connect and support the first and second plates." In addition, a search of other information found that their current focus is on developing corresponding raw material powders or optimizing powder metallurgy processes. However, powder metallurgy processes also face the problem of difficulty in preparing a controllable internal microenvironment. Summary of the Invention

[0004] The present invention addresses the deficiencies of the prior art and provides a method for preparing a capillary wick with a controllable internal microenvironment.

[0005] The present invention provides a method for preparing a capillary wick with a controllable internal microenvironment; the method adopts a selective laser sintering (SLM) process to prepare a blank, and then performs A heat treatment to obtain the capillary wick with a controllable internal microenvironment, which has a high-throughput capillary wicking capacity.

[0006] The raw material powder consists of metal powder and additives, wherein the additives account for 0.1% to 30% by weight, preferably 0.2-20%, more preferably 0.2-15%, and even more preferably 8-12%, and the balance is metal powder;

[0007] The metal powder is copper powder with a purity of more than 99%, an average particle size D of 10 to 300 μm, and a particle size distribution δ of ≥ 70% within ± 20% of the average particle size D value;

[0008] Preferably, the metal powder is copper powder with a purity of 99.9% or more, an average particle size D of 80 to 200 μm, and a particle size distribution δ of ≥80% within ±20% of the average particle size D value;

[0009] Further preferably, the metal powder is copper powder with a purity of 99.9% or more, an average particle size D of 80 to 150 μm, and a particle size distribution δ of ≥90% within ±20% of the D value;

[0010] The additive consists of two components: a stabilizer and a strengthener, wherein the stabilizer is at least one of copper carbonate and copper bicarbonate; the strengthener is titanium hydride, and the strengthener accounts for 0.1% to 20% of the total mass of the additive, preferably 0.1% to 10% of the total mass of the additive; more preferably 0.2% to 5% of the total mass of the additive, and even more preferably 2-3%.

[0011] After the metal powder and additives are prepared in proportion and evenly mixed, SLM forming is carried out on the lower cover plate: during forming, the laser power is 280-400W, the scanning rate is 600-1200mm / s, and the scanning spacing is D±20%; preferably, the laser power is 295-375W, the scanning rate is 800-1150mm / s, and the scanning spacing is D±15%; further preferably, the laser power is 300-360W, the scanning rate is 900-1100mm / s, and the scanning spacing is D±10%.

[0012] After SLM forming, A heat treatment is performed to obtain a lower cover plate with a capillary wick with controllable internal microenvironment. The process of A heat treatment is: 580~860℃×10~120min, and the protective atmosphere is (N2 and / or Ar2)+H2 mixed gas, wherein the volume proportion of H2 is 3-75%; preferably, the process of A heat treatment is: 580~720℃×15~90min, and the protective atmosphere is (N2 or Ar2)+H2 mixed gas, wherein the volume proportion of H2 is 3-30%; further preferably, the process of A heat treatment is: 580~640℃×20~60min, and the protective atmosphere is (N2 and / or Ar2)+H2 mixed gas, wherein the volume proportion of H2 is 5-10%.

[0013] In particular, the capillary wick with a controllable internal microenvironment is comprised of N circumferential tapered frames, P conical centripetal frames, guide posts, conical holes, and grooves, all fabricated in a single step via SLM. N is greater than or equal to 2, preferably 3-8; P is greater than or equal to 4, preferably 8-24. That is, the N circumferential tapered frames, P conical centripetal frames, guide posts, conical holes, and grooves are made of the same material.

[0014] In particular, the lower cover plate with a capillary wick with a controllable internal microenvironment, the capillary wick is composed of 6 circles of tapered circumferential skeletons, 16 tapered centripetal skeletons, guide force columns, tapered holes, and grooves, all of which are formed in one step by SLM.

[0015] There are 16 centripetal ribs, evenly spaced, with the angle between adjacent ribs at 22.5 degrees. Conical holes are provided on the circumferential ribs and in the center of the heat source. These holes are 0.3mm deep, with a large end diameter of 0.35mm and a small end diameter of 0.20mm. The minimum spacing between adjacent conical holes is 1.5mm.

[0016] The width of the upper surface of the circumferential skeleton is 0.55mm, and the width of the lower surface is 0.85mm; the thickness is 0.3mm; the initial value of the center radius of the circumferential skeleton is 7mm, and the outward increment is 1.5mm.

[0017] The width of the upper surface of the centripetal skeleton is 0.55 mm, the width of the lower surface is 0.85 mm, the thickness is 0.3 mm, and 16 centripetal skeletons are evenly distributed at equal angles in the circumferential direction.

[0018] The equivalent diameter of the guide column is 0.45mm; the height is 0.35mm, and the minimum spacing between adjacent upper and lower connecting columns is 1.5mm.

[0019] A layer of 0.08mm copper mesh is sintered on the upper cover.

[0020] The upper cover with a copper mesh and the lower cover with a capillary wick with a controllable internal microenvironment are welded, vacuumed, filled with liquid and sealed to form a closed cavity. The amount of liquid filled in the cavity is 0.7 to 1.3 times the total amount of capillary liquid, and the vacuum degree in the cavity is 0.01 to 10Pa.

[0021] During use, the outer layer of the lower cover contacts a heat source. When heated, the heat is transferred to the lower cover and the wick, causing the liquid medium in the wick to heat up. Once the vaporization condition is reached, the liquid medium rapidly vaporizes and absorbs heat. The vaporized bubbles gather and leave the surface of the wick, carrying away heat to form a gaseous medium. The outer surface of the upper cover contacts the heat sink and is in a low-temperature state. The gaseous medium containing heat condenses into a liquid medium on the low-temperature inner surface of the upper cover and the copper mesh. The released heat is transferred to the heat sink and dissipated. Under the capillary force of the guide force columns connected to the upper and lower capillary structures, the liquid medium flows back to the wick, where it is then vaporized by the heat, condenses and liquefies on the inner surface of the upper cover and the copper mesh, and then flows back to the wick. This cycle repeats, forming a cyclic medium capable of rapidly transferring heat through liquid-to-vapor phase change, ultimately achieving the effect of equalizing heat between the hot and cold ends. At the same time, the gaseous medium can form convection in the inner cavity, and the liquid medium circulates under the capillary force of the upper and lower structures, effectively achieving the effect of equalizing heat transfer at different locations.

[0022] The effective thermal conductivity of the heat spreader prepared by the present invention is higher than 0.6×10 4 W / m·K, heat flux is not less than 60W / cm 2 The temperature difference of the heat spreader within the power range is no more than 15°C, and after optimization, the temperature difference can be no more than 10°C. In particular, the effective thermal conductivity reaches 1.1×10 4 W / m·K and above, heat flux ratio can reach 420W / cm 2 Above, the temperature difference within the power range is not greater than 8℃.

[0023] Principles and advantages

[0024] The present invention adopts a method for preparing a capillary wick with a controllable internal microenvironment, and can customize and prepare complex capillary wicks by adopting a SLM forming method.

[0025] The capillary structure of conventional vapor chambers is a conventional linear or planar structure composed of grooves, meshes, wires, and powders. These structures are manufactured through machining, pressing, and sintering, requiring multiple steps and complex processes with numerous parameters that require strict control at every stage. The structure is identical around the heat source, resulting in a single capillary function and limited performance. The high temperature near the heat source requires a large amount of medium for phase change heat transfer, making conventional structures insufficiently sufficient and leading to rapid local temperature rise. Capillary wicks with a controllable internal microenvironment, however, allow for specialized capillary structures with varying designs in different locations, such as centripetal gradient capillary structures. While such complex capillary structures are difficult to achieve using conventional methods, SLM with appropriate parameters allows for the convenient three-dimensional laser stereolithography (3D) process to produce customized capillary structures of various shapes and specifications. The manufacturing process is simple and controllable, allowing for the creation of capillary wicks with complex structures in a single, customized process.

[0026] Conventional 3D printing methods are often used to process dense blanks. There is no mature method for producing capillary wicks with controllable internal microenvironment. The porous materials produced by existing 3D printing methods have the following defects and are all single structures:

[0027] 1) The macroscopic pores formed by the areas where the printing track does not reach the part, the pores formed after the binder in the part skeleton is heated, decomposed or dissolved and removed, or the pores formed between the laser scanning melt traces. The pores are wide and the printed area is still dense, which is not suitable for the preparation of capillary wicks with controllable internal microenvironment.

[0028] 2) The pores formed by gas dissolving in the molten metal during the sintering process are small, but some of the molten gas (such as ammonia) is harmful to the human body or may cause metal pollution and affect the performance of the product;

[0029] 3) The process for forming pores by the accumulation of gaps between powder particles is not yet mature.

[0030] The SLM forming method developed in the present invention optimizes the composition of raw materials, printing parameters and post-processing technology to prepare through-holes. The pores are composed of composite three-dimensional structures of at least one of micropores, macropores or grooves. Multiple pores are combined to form multi-dimensional three-dimensional capillaries, which coordinate with each other and can play a good role in transporting liquid media.

[0031] 1. Raw Materials: The raw material powder for conventional 3D printing is a fine-particle spherical powder, which facilitates fluidity and dimensional accuracy control. The powder selected for this scheme can be a coarser-particle powder. This coarse-particle powder can form pores with a certain gap width, which is beneficial to improving liquid absorption capacity. Powders that are too fine and / or have too wide a particle size range are prone to printing dense blanks, which is detrimental to improving liquid absorption capacity. The stabilizer in the appropriate additive is copper compound particles. During the printing process, high temperatures can release gases. These gases are non-toxic and can form pores, which play a role in pore formation. At the same time, after SLM and heat treatment, oxygen-containing copper substances can form a rough surface after reduction. Both of these effects can stabilize and improve the capillary force of the wick. Hydride can release hydrogen when heated at high temperatures during printing and heat treatment. It reacts with free oxygen in the powder to form water vapor, which plays a role in pore formation and deoxygenation, thereby improving capillary force. At the same time, titanium can react with copper to increase the strength of copper, further strengthening it. If the additives are too little, it is difficult to achieve the stabilization and strengthening effects; if the additives are too much, it will cause excessive copper oxides, which may still remain after SLM and heat treatment, and may reduce the capillary force.

[0032] 2. Forming Process: By adjusting the SLM forming process parameters, the pore size and capillary suction force of the capillary wick can be effectively controlled. Conventional 3D printing processes use high laser power (greater than 360W), slow scanning speeds (less than 900mm), and small scanning intervals to produce a continuous and dense blank. The SLM forming method developed in this invention, within a certain scanning rate range, can achieve a semi-fused powder state by increasing the scanning interval and reducing the laser power, facilitating the formation of a porous capillary wick.

[0033] 3. Heat Treatment A: Proper heat treatment A can further stabilize the copper powder and sinter it into a capillary wick with strong liquid absorption capacity. If the treatment temperature is too low, some unstabilized copper powder will be difficult to weld. If the treatment temperature is too high, the tendency to fuse increases, porosity decreases, and capillary absorption is severely affected. N2 or Ar2 acts as a protective agent during the heat treatment, while hydrogen reduces copper oxides, thereby enhancing the capillary force of the wick. Capillary wicks are sintered from oxygen-containing raw material powders. While some oxygen can be reduced by hydrides, some remains in the blank. Heat treatment A, under high temperature and a hydrogen-containing atmosphere, effectively reduces copper oxides and enhances capillary force. The hydrogen content directly affects the reduction effect. If the hydrogen content in the atmosphere is too low or absent, copper oxides will remain in the wick, reducing the capillary force. Within a certain range, hydrogen content can effectively reduce copper oxides and form pure copper with a slightly rough surface, further enhancing the capillary force. Excessive hydrogen content increases cost and reduces safety, so the hydrogen content should be appropriately controlled. By optimizing and controlling the temperature, time, and atmosphere conditions of heat treatment A, the capillary force of the capillary wick with a controllable internal microenvironment can be effectively improved, thereby improving the performance of the heat spreader.

[0034] In addition, through the SLM forming method developed by the present invention, a tapered hole and / or trapezoidal groove structure with strong evaporation ability can be customized and processed in the capillary wick at the same time. This tapered hole or trapezoidal groove with an inclined shape and the rough capillaries on its surface allow the bubbles formed by the heat source to quickly gather, rise and be removed on the inclined surface, reducing the buoyancy in the liquid medium pool and the surface tension in the capillary pores, thereby increasing the removal speed of the medium bubbles from the capillary structure in the heated area and improving the heat absorption and heat transfer capabilities.

[0035] In summary, through the SLM forming method developed in the present invention, customized design and processing of various combinations of capillary structures can be achieved, so that the composition, shape and distribution of microenvironments such as conical holes, grooves, columns, cavities and porous structures can be controlled, and the role of these components can be fully utilized, and ultimately the internal microenvironment of the capillary structure of the heat spreader can be controlled to meet the high performance requirements of the heat spreader. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of a capillary wick with a controllable internal microenvironment.

[0037] Figure 2 This is a physical object printed using the printing parameters and raw materials of Example 1. DETAILED DESCRIPTION

[0038] Example 1

[0039] A method for preparing a capillary wick with a controllable internal microenvironment is disclosed. The method uses a selective laser sintering (SLM) process to prepare a capillary structure with a controllable internal microenvironment on a lower cover plate, and then performs a heat treatment A to obtain the capillary wick with a controllable internal microenvironment. The specific process and preparation process are as follows:

[0040] The raw material powder consists of two parts: metal powder and additives. The additives account for 10% by weight, and the rest is metal powder.

[0041] The metal powder is copper powder with a purity of ≥99.9%, an average particle size D of 120 μm, and a particle size distribution δ of ≥92% within ±20% of the D value;

[0042] The additives are copper bicarbonate and titanium hydride powder, wherein the titanium hydride content is 2.5% and the balance is copper bicarbonate;

[0043] After the metal powder and additives are prepared in proportion and evenly mixed, SLM forming is performed on the lower cover plate: during forming, the laser power is 345W, the scanning rate is 1000mm / s, and the scanning spacing is 125μm.

[0044] After SLM forming, A heat treatment is performed to produce a lower cover plate with an internal microenvironment controllable capillary wick. The A heat treatment process is: 600±5℃×30min, and the protective atmosphere is N2+H2 mixed gas, in which the volume proportion of H2 is 8%.

[0045] In particular, the lower cover plate with the capillary wick with controllable internal microenvironment, the capillary wick consists of a capillary pore layer, 6 circumferential skeletons, 16 centripetal skeletons, guide force columns, conical holes, and grooves, which are uniformly formed in one step by SLM.

[0046] There are 16 centripetal ribs, evenly spaced, with the angle between adjacent ribs at 22.5 degrees. Conical holes are provided on the circumferential ribs and in the center of the heat source. These holes are 0.3mm deep, with a large end diameter of 0.35mm and a small end diameter of 0.20mm. The minimum spacing between adjacent conical holes is 1.5mm.

[0047] The width of the upper surface of the circumferential skeleton is 0.55mm, and the width of the lower surface is 0.85mm; the thickness is 0.3mm; the initial value of the center radius of the circumferential skeleton is 7mm, and the outward increment is 1.5mm.

[0048] The width of the upper surface of the centripetal skeleton is 0.55 mm, the width of the lower surface is 0.85 mm, the thickness is 0.3 mm, and 16 centripetal skeletons are evenly distributed at equal angles in the circumferential direction.

[0049] The equivalent diameter of the upper and lower connected guide columns is 0.45mm; the height is 0.35mm, and the minimum spacing between adjacent guide columns is 1.5mm.

[0050] A layer of 0.08mm copper mesh is sintered on the upper cover.

[0051] The upper cover with the copper mesh and the lower cover with the capillary wick with controllable internal microenvironment are welded, evacuated, filled with liquid and sealed to form a closed cavity. The amount of liquid filled in the cavity is 1.05 times the total amount of capillary liquid, and the vacuum degree in the cavity is 0.5Pa.

[0052] The prepared vapor chamber has a porosity of 56.8% and an effective thermal conductivity of 1.25×10 4 W / m·K, heat flux is 430W / cm 2 The temperature difference within the power range of the vapor chamber is no more than 6.5°C. When the macroscopic shape, size, and material are completely consistent, the effective thermal conductivity of the product obtained by this process is better than that of the product obtained by hot pressing, and the temperature difference within the power range is smaller than that of the product obtained by hot pressing. This proves that the construction of the internal microenvironment is more reasonable.

[0053] Example 2

[0054] A method for preparing a capillary wick with a controllable internal microenvironment, wherein the metal powder is copper powder with a purity of ≥99.5%, an average particle size D of 15 μm, a particle size distribution δ of ≥72% within ±20% of the D value, and an additive accounting for 0.2% (of which titanium hydride accounts for 0.15% of the additive, and the balance is copper bicarbonate. Other parameters are the same as in Example 1.

[0055] The prepared vapor chamber has a porosity of 46.5% and an effective thermal conductivity of 0.72×10 4 W / m·K, heat flux is 65W / cm 2 The temperature difference of the heat sink within the power range is no more than 13.5℃.

[0056] Example 3

[0057] A method for preparing a capillary wick with a controllable internal microenvironment, wherein the SLM forming process comprises a laser power of 290 W, a scanning rate of 1100 mm / s, and a scanning pitch of 100 μm. A heat treatment process A after SLM forming is performed at 850±5°C for 100 minutes, using a protective atmosphere of a N2+H2 mixture, wherein the H2 accounts for 4% by volume. Other parameters are the same as those in Example 1.

[0058] The prepared vapor chamber has a porosity of 43.8% and an effective thermal conductivity of 0.65×10 4 W / m·K, heat flux is 68W / cm 2 The temperature difference of the heat sink within the power range is no more than 14.5℃.

[0059] Example 4

[0060] A method for preparing a capillary wick with a controllable internal microenvironment, wherein the metal powder is copper powder with a purity of ≥99.95%, an average particle size D of 105 μm, a particle size distribution δ of ≥90% within ±10% of the D value, and an additive ratio of 10% (of which titanium hydride accounts for 4% of the additive, and the remainder is copper carbonate). The SLM forming process comprises a laser power of 350 W, a scanning rate of 1050 mm / s, and a scanning pitch of 120 μm. A heat treatment process A after SLM forming is performed at 600±5°C for 30 minutes, using an Ar2+H2 mixed gas as the protective atmosphere, wherein the H2 accounts for 8% by volume. Other parameters are the same as those in Example 1.

[0061] The prepared vapor chamber has a porosity of 54.6% and an effective thermal conductivity of 1.18×10 4 W / m·K, heat flux is 436W / cm 2 The temperature difference of the heat sink within the power range is no more than 6℃.

[0062] Comparative Example 1

[0063] A method for preparing a capillary wick with a controllable internal microenvironment, wherein the SLM forming process is as follows: a laser power of 450W, a scanning rate of 550mm / s, and a scanning pitch of 60μm. Other parameters are the same as those in Example 1.

[0064] The prepared vapor chamber has a porosity of 10.8% and an effective thermal conductivity of no more than 0.2×10 4 W / m·K, heat flux not higher than 20W / cm 2 The temperature difference of the heat sink within the power range exceeds 30℃.

[0065] Comparative Example 2

[0066] A method for preparing a capillary wick with a controllable internal microenvironment, wherein the heat treatment process A is: 950°C × 150 min, the protective atmosphere is N2 gas, and the volume proportion of H2 is 0%. Other parameters are the same as those in Example 1.

[0067] The prepared vapor chamber has a porosity of 40.8% and an effective thermal conductivity of no more than 0.3×10 4 W / m·K, heat flux not higher than 20W / cm 2 The temperature difference of the heat sink within the power range exceeds 30℃.

[0068] Comparative Example 3

[0069] A method for preparing a capillary wick with a controllable internal microenvironment, wherein the heat treatment process A is: 400°C × 10 min, the protective atmosphere is N2+H2 gas, and the volume proportion of H2 is 8%. Other parameters are the same as those in Example 1.

[0070] The prepared vapor chamber has a porosity of 50.6% and an effective thermal conductivity of no more than 0.4×10 4 W / m·K, heat flux not higher than 35W / cm 2 The temperature difference of the heat sink within the power range exceeds 30℃.

[0071] Comparative Example 4

[0072] A method for preparing a capillary wick with a controllable internal microenvironment, wherein the metal powder is copper powder with a purity of 98.5% or higher, an average particle size D of 8 μm or less, a particle size distribution δ of 70% or less within ±20% of the D value, and no additives. Other parameters are the same as those in Example 1.

[0073] The prepared vapor chamber has a porosity of 40.6% and an effective thermal conductivity of 0.42×10 4 W / m·K, heat flux is 46W / cm 2 The temperature difference of the heat sink within the power range exceeds 18℃.

Claims

1. A method for preparing a capillary wick with a controllable internal microenvironment; characterized in that: Select raw material powder; use selective laser sintering process to prepare blanks, and then heat treat A to obtain capillary wicks with controllable internal microenvironment; The raw material powder consists of two parts: metal powder and additives, with the additives accounting for 0.2-15% by weight and the balance being metal powder; The metal powder is copper powder with a purity of more than 99%, an average particle size D of 10~300μm, and a particle size distribution δ ≥ 70% within ±20% of the average particle size D value; The additive is composed of two components: a stabilizer and a strengthener, wherein the stabilizer is at least one of copper carbonate and copper bicarbonate; the strengthener is titanium hydride, and the strengthener accounts for 0.2% to 5% of the total mass of the additive; After the metal powder and additives are mixed in proportion and evenly, SLM forming is performed on the lower cover plate: during forming, the laser power is 280-400W, the scanning rate is 600-1200 mm / s, and the scanning interval is the average powder particle size D ± 20%; After selective laser sintering, A heat treatment is performed to obtain a lower cover plate with a capillary wick with controllable internal microenvironment. The A heat treatment process is: 580~720℃×15~90min, and the protective atmosphere is a mixed gas composed of N2+Ar2+H2, in which the volume proportion of H2 is 3-30%; wherein the content of N2 is greater than or equal to 0, the content of Ar2 is greater than or equal to 0, and N2 and Ar2 are not 0 at the same time.

2. The method for preparing a capillary wick with a controllable internal microenvironment according to claim 1, characterized in that: The metal powder is copper powder with a purity of more than 99.9%, an average particle size D of 80~200μm, and a particle size distribution δ≥80% within ±20% of the average particle size D value.

3. The method for preparing a capillary wick with a controllable internal microenvironment according to claim 2, characterized in that: The metal powder is copper powder with a purity of more than 99.9%, an average particle size D of 80-150 μm, and a particle size distribution δ of ≥90% within ±20% of the average particle size D value.

4. The method for preparing a capillary wick with a controllable internal microenvironment according to claim 2, characterized in that: During selective laser sintering, the laser power is 295-375W, the scanning rate is 800-1150 mm / s, and the scanning spacing is the average particle size D±15%.

5. The method for preparing a capillary wick with controllable internal microenvironment according to claim 4, characterized in that: During selective laser sintering, the laser power is 300-360W, the scanning rate is 900-1100 mm / s, and the scanning spacing is the average particle size D±10%.

6. The method for preparing a capillary wick with a controllable internal microenvironment according to claim 1, characterized in that: The heat treatment process is: 580~640℃×20~60min, the protective atmosphere is a mixed gas composed of N2+Ar2+H2, of which the volume proportion of H2 is 5-10%; the N2 content is greater than or equal to 0, and the Ar2 content is greater than or equal to 0.

7. The method for preparing a capillary wick with a controllable internal microenvironment according to claim 1, characterized in that: A capillary wick with a controllable internal microenvironment is attached to the lower cover plate. The capillary wick consists of N circumferential cone skeletons, P centripetal cone skeletons, guide columns, conical holes, and grooves, all of which are formed in one step by SLM; N is greater than or equal to 2; and P is greater than or equal to 4.

8. The method for preparing a capillary wick with controllable internal microenvironment according to claim 7, characterized in that: The lower cover plate has a capillary wick with a controllable internal microenvironment. The capillary wick consists of 6 circumferential cones, 16 centripetal cones, guide columns, conical holes, and grooves, all manufactured in one step by SLM. There are 16 centripetal skeletons, and the 16 centripetal skeletons are evenly distributed, that is, the angle between adjacent centripetal skeletons is 22.5 degrees; conical holes are provided on the circumferential skeleton and the center area of ​​the heat source, with a depth of 0.3mm; the large end diameter is 0.35mm, and the small end diameter is 0.20mm; the minimum spacing between adjacent conical holes is 1.5mm; The width of the upper surface of the circumferential skeleton is 0.55mm, the width of the lower surface is 0.85mm, and the thickness is 0.3mm. The initial value of the center radius of the circumferential skeleton is 7mm, and the outward increment is 1.5mm. The width of the upper surface of the centripetal skeleton is 0.55mm, the width of the lower surface is 0.85mm, and the thickness is 0.3mm. There are 16 centripetal skeletons evenly distributed at equal angles in the circumferential direction. The equivalent diameter of the guide column is 0.45mm; the height is 0.35mm, and the minimum spacing between adjacent upper and lower connecting columns is 1.5mm.

9. The method for preparing a capillary wick with a controllable internal microenvironment according to claim 7, characterized in that: A layer of 0.08 mm copper mesh is sintered on the upper cover plate. The upper cover plate with the copper mesh and the lower cover plate with a capillary wick with a controllable internal microenvironment are welded, evacuated, filled with liquid, and sealed to form a closed cavity. The amount of liquid filled in the cavity is 0.7 to 1.3 times the total amount of capillary liquid, and the vacuum degree in the cavity is 0.01 to 10 Pa.

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