CN114888304A - Manufacturing method of composite porous structure liquid absorption core - Google Patents

Abstract

The invention discloses a manufacturing method of a liquid-absorbing core with a composite porous structure, and relates to the processing technology of the liquid-absorbing core. In the present invention, a three-dimensional skeleton structure model is first designed, and then the designed three-dimensional skeleton structure model is imported into a 3D printing system, and metal powder is used as a raw material for printing by a laser sintering process, so as to obtain a liquid-absorbing core skeleton structure containing micron pores; Then, oxygen is introduced into the printer cavity, the oxygen content is 2%-16%, the laser parameters of the printer are adjusted, and the surface laser printing is performed on the skeleton structure of the liquid-absorbing core containing the micro-pores after printing, and the above steps are repeated 2-10 times to obtain A composite porous structure absorbent core with controllable hydrophilicity and hydrophobicity. The invention has the advantages of simple manufacturing method and few consumables, and can improve the capillary force of the liquid absorbing core, reduce the heat transfer resistance, facilitate the adjustment of the surface wettability, and strengthen the heat transfer and condensation efficiency of the liquid absorbing core.

Description

A kind of manufacturing method of composite porous structure liquid absorbent core

technical field

The invention belongs to the technical field of liquid absorbent core processing, and in particular relates to a method for manufacturing a liquid absorbent core with a hydrophilic and hydrophobic controllable composite porous structure.

Background technique

With the development of miniaturization, integration and high performance of electronic equipment, the performance degradation of equipment caused by high heat flux density gradually appears, and the problem of thermal management of electronic equipment is becoming more and more serious. When the operating temperature of electronic equipment exceeds the rated operating temperature by 10°C, its reliability is reduced by 50%. The ever-increasing demand for heat dissipation has become a bottleneck restricting the application of electronic components. Therefore, phase-change heat transfer devices such as heat pipes and vapor chambers are widely used for effective thermal management of electronic products due to their high thermal conductivity, high stability, high reliability, and high cooling capacity. The wick generates capillary pressure, which is then used to drive the working fluid from the condenser to the evaporator to maintain the operation of the cooling system. It is the most critical component in the phase change cooling system, and its performance directly affects the heat pipe or temperature. cooling performance of the plate. At present, the common types of absorbent cores mainly include metal powder sintered absorbent cores, wire mesh absorbent cores and groove or channel absorbent cores.

The existing liquid-absorbing core manufacturing method is mainly prepared by sintering method, and the sintering material is metal powder, metal wire mesh and metal fiber. The metal powder sintered absorbent core has the advantages of high mechanical strength and large capillary force, but the permeability of the absorbent core is low and the fluid flow resistance is large, which is not conducive to the gas-liquid separation of the phase change of the working medium when the absorbent core is working; at the same time, the preparation cycle The size of the absorbent core needs to be controlled by machining the corresponding mold, and the pore size and porosity are not controllable. The wire mesh absorbent core has the advantages of high porosity, simple processing technology and low cost, but the absorbent core has the disadvantages of low capillary force and large thermal resistance between different wire mesh layers, and the heat transfer effect is poor. Except for the liquid-absorbent core prepared by the above-mentioned sintering method, the groove or channel-type liquid-absorbent core formed by machining has low capillary force and is not suitable for high heat flux density electronic equipment. In addition, the regulation of the hydrophilicity and hydrophobicity of the absorbent core plays a key role in improving the heat transfer performance of the heat pipe uniform temperature plate, while the existing absorbent core hydrophilicity and hydrophobicity regulation requires surface post-treatment, and the production process is complicated, which is inconvenient for quantitative production.

The composite structure liquid-absorbent core combines the characteristics of various liquid-absorbent cores and makes up for the deficiencies of the above-mentioned liquid-absorbent cores. To this end, the patent of the patent number CN104075603A discloses a heat pipe composite liquid absorbent core and a preparation method thereof. The liquid absorbent core is composed of a metal outer sleeve and a metal porous flow channel, and has a double-porous structure, which improves the capillary pressure and penetration. At the same time, the metal porous flow channel provides a working medium return channel, which reduces the liquid return resistance, thereby improving the heat transfer performance of the heat pipe. However, due to the need to combine the wire cutting method to make the mold in advance, the process is cumbersome, and the micropores of the liquid-absorbing core are randomly distributed, which is not conducive to gas-liquid transportation. Patent Publication No. CNC104776742A proposes a method for manufacturing a composite liquid-absorbent core. The liquid-absorbent core structure adopts the form of combined sintering of wire mesh and foamed copper or copper powder, and sintered foamed copper or copper powder on at least one surface of the wire mesh layer. The patented procedure is cumbersome, the process is complicated, and the pore structure cannot be well controlled. The patent publication number CN110385436A discloses a metal absorbent core with multi-pore structure features and a manufacturing method thereof. The microstructure formed by the powder bonding gaps produced by the absorbent core can meet the needs of improving capillary performance, but the micropores are random. Combination, uncontrollable pores lead to large gas-liquid flow resistance in the absorbent core, which is not conducive to the heat dissipation requirements of high heat flux density.

SUMMARY OF THE INVENTION

Aiming at the deficiencies of the prior art, the present invention provides a method for manufacturing a liquid absorbent core with a composite porous structure. The composite porous liquid absorbent core manufacturing method has simple process, controllable pore structure size and porosity, and at the same time realizes controllable manufacturing of the surface hydrophilicity and hydrophobicity of the liquid absorbent core, and has the advantages of large capillary force and small gas-liquid flow resistance.

The manufacturing method of the composite porous structure liquid absorbent core of the present invention comprises the following steps:

(1) Design a three-dimensional skeleton structure model; the model described in the present invention is designed by three-dimensional software, and the designed model is composed of a millimeter macroporous skeleton structure inside the nested liquid absorbent core. The model is imported into the 3D printing system to control the printing process and sliced. Additive manufacturing afterwards;

(2) Import the designed 3D skeleton structure model into the 3D printing system, use metal powder as raw material, use the laser sintering process to print, and control the laser power, scanning speed, scanning distance and powder layer thickness to obtain micron pores The porous skeleton structure of the absorbent core;

(3) After printing, oxygen is introduced into the printer cavity, and the oxygen content is 2%-16%;

(4) Perform surface laser printing on the porous skeleton of the absorbent core containing micro-pores, adjust the 3D printing laser power to 5-100W, the scanning speed is 5-200mm/s, the laser pulse frequency is 10-100kHz, and the scanning spacing is 0.01-0.1mm;

(5) Step (4) is repeated 2 to 10 times to form an orderly micro-nano pore structure on the surface of the absorbent core, so as to realize a composite porous structure absorbent core with controlled production of gradient pores and surface hydrophilicity and hydrophobicity. Preferably, the particle size of the metal powder is 10-80 μm.

Preferably, the laser power is 140-2000W, the scanning speed is 2000-4000 mm/s, and the printing powder layer thickness is 0.1-1 mm.

Preferably, in the laser sintering process, the laser scanning rotation angle is 90°, the scanning spacing is 0.1 mm-1.2 mm, powder is laid layer by layer, and unidirectional cross-line scanning is performed.

Preferably, the size of the micro-nano pores in the liquid absorbent core is 0.5-200 μm, and the porosity is controlled to be 5%-90%.

Preferably, the overall thickness of the composite porous structure liquid-absorbent core is 0.1-6 mm.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The composite gradient structure of the liquid-absorbent core of the present invention is designed by three-dimensional software, and the porous liquid-absorbent core is directly printed and formed by 3D printing technology, and the size and porosity of the composite pore structure can be precisely controlled. Without the need for mold development and additional processing, various forms of composite porous structures can be formed at one time, such as the development and manufacture of liquid-absorbing wicks such as loop heat pipes, vapor chambers, and capillary pump loop heat pipes. In addition, the composite gradient porous structure realizes the composite of micro-nano-scale pores and millimeter-scale pores, which can reduce the gas-liquid flow resistance while satisfying the excellent capillary performance of the absorbent core.

(2) The composite porous structure liquid absorbent core of the present invention can control the hydrophilicity and hydrophobicity of the liquid absorbent core while forming the composite gradient pores at one time, so as to realize the one-step formation of gradient pores + interface control, and no additional surface post-treatment is required. The fabricated composite gradient porous liquid absorbent core can realize the zone regulation of enhanced heat transfer and condensation.

Description of drawings

Fig. 1 is a three-dimensional model diagram of the composite porous structure liquid absorbent core of the present invention.

Fig. 2 is the structure of the composite porous absorbent core with the skeleton containing micro-pores in Example 1 of the present invention.

Fig. 3 is the micro-pore structure inside the skeleton of the composite gradient porous liquid-absorbent core in Example 1 of the present invention.

FIG. 4 shows the surface morphology characteristics and wettability measurement of the composite porous structure liquid-absorbent core in Example 1 of the present invention.

Fig. 5 is the micro-pore structure inside the liquid-absorbing framework of the composite porous structure in Example 2 of the present invention.

FIG. 6 is a comparison of thermal resistance of the skeleton comprising porous absorbent core and the absorbent core of solid skeleton structure in Example 2 of the present invention.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments.

Example 1

A manufacturing method of a composite porous structure liquid absorbent core, the specific steps are as follows:

The skeleton structure of the composite porous absorbent core was constructed by using 3D modeling software. The wall thickness of the porous structure was designed to be 0.5 mm, the pore structure was designed to be rectangular, and the length and width of the pore structure were 1 × 0.5 mm. Figure 1 shows the three-dimensional model of the additively manufactured composite porous absorbent core.

The model is imported into the 3D printing system and processed by slicing for additive manufacturing. The metal powder material selected in this example is AlSi10Mg, and the powder particle size ranges from 10 to 60 μm.

Set the printing laser power to 380W, the scanning speed to 3000mm/s, the powder layer thickness to be 0.04mm, and the laser scanning spacing to be 0.1mm to ensure that the porous skeleton can have a good forming effect and make it have good mechanical strength. .

The laser rotation angle of the 3D printer is controlled to be 90°. During the construction process, the laser scanning paths intersect with each other, and the composite porous structure is formed by layer-by-layer line scanning.

The base plate of the 3D printing worktable is connected by silica gel or bolts to the base plate of the heat pipe to be manufactured. The laser scans the outline of the base plate. After the scanning is completed, the composite porous liquid wick structure is fabricated on the base plate. FIG. 2 and FIG. 3 print a composite porous structure liquid absorbent core with a skeleton containing micro-pores and a micro-pore structure inside the skeleton in this embodiment.

After the above-mentioned composite porous structure is printed, oxygen is introduced into the cavity of the 3D printing chamber to keep the oxygen content in the cavity at 8%.

The 3D printing laser power was adjusted to 50W, the scanning speed was 80mm/s, the laser pulse frequency was 60kHz, and the scanning spacing was 0.05mm, and the surface of the composite pore absorbent core was printed and processed.

Keep the above laser parameters unchanged, and repeat the scanning of the surface of the porous absorbent core structure 5 times to ensure that the surface of the absorbent core forms a uniform micro-nano pore structure, so as to control the surface of the composite porous absorbent core to exhibit hydrophilic properties, and the hydrophilic surface The heat transfer limit of wick products can be significantly enhanced. Figure 4 shows the morphology and wettability measurement of the surface of the composite porous structure after surface printing. The surface of the structure shows significant hydrophilicity.

After the composite porous structure wick is printed, unscrew the bolts or heat to make the silica gel fail to remove the printed wick without subsequent machining such as wire cutting. Ultrasonic cleaning removes loose, unmelted powder on the surface of the wick for subsequent use.

In the examples, the internal pore characteristics of the composite porous absorbent core skeleton were measured by a mercury porosimeter, the pore diameter was 80 μm, and the porosity was 25%.

Example 2

A manufacturing method of a composite porous structure liquid absorbent core, the specific steps are as follows:

Three-dimensional modeling software was used to build a composite porous skeleton structure, and the size of the macropores in the wick model was 0.5 mm × 1 mm.

The model is processed for additive manufacturing after slicing. The difference from Example 1 is that the metal powder material used in this example is 316L, and the powder particle size ranges from 20 to 60 μm.

Set the laser power for printing to 800W, the scanning speed to 3600mm/s, the thickness of the powder coating layer to be 0.03mm, the laser scanning distance to be 0.12mm, and the laser rotation angle of the 3D printer to be controlled to be 60°. During the construction process, the laser scanning path is Cross each other, and line scan layer by layer to form a composite structure.

The base plate of the 3D printing worktable is connected by silica gel or bolts to the base plate of the heat pipe to be manufactured. The laser scans the outline of the base plate. After the scanning is completed, the composite porous liquid wick structure is fabricated on the base plate. FIG. 5 shows the smaller-sized composite porous skeleton structure containing micro-pores printed in Example 2.

After the above-mentioned composite porous structure is printed, oxygen is introduced into the cavity of the 3D printing chamber to keep the oxygen content in the cavity at 12%.

The 3D printing laser power was adjusted to 30W, the scanning speed was 60mm/s, the laser pulse frequency was 20kHz, and the scanning spacing was 0.01mm, and the surface post-treatment of the 3D printing composite porous wick was performed.

Keeping the above laser parameters unchanged, the surface of the porous liquid absorbent core structure is repeatedly scanned 8 times to ensure that a uniform micro-nano pore structure is formed on the surface of the liquid absorbent core.

After the composite porous structure wick is printed, unscrew the bolts or heat to make the silica gel fail to remove the printed wick. Ultrasonic cleaning of loose unmelted powder on the surface of the wick for subsequent use.

In the embodiment, the inner pore diameter and porosity of the composite porous liquid-absorbing core skeleton are measured by mercury porosimeter to be 45 μm and 20%, respectively.

In order to further illustrate the advantages of the composite porous absorbent core structure in the embodiment in enhancing the heat transfer performance of the heat pipe, Figure 6 shows the mm/micron composite porous structure + hydrophilic surface fabricated by the process in Example 2 for loop suction. Comparison of heat transfer thermal resistance of liquid cores. It can be seen from Figure 6 that the composite porous liquid absorbent core with micro-nanopores inside the skeleton controlled by the surface hydrophilicity and hydrophobicity has significantly lower heat transfer resistance and higher heat transfer heat load than the solid skeleton structure.

The invention can manufacture and form the composite porous liquid absorbent core of millimeter scale and micro-nano scale at one time without additional machining, the macroporous structure in the liquid absorbent core is flexible in design and has various forms, while the micro-nano pore size and porosity structure can be processed through the process The additive manufacturing process is designed and controlled, and the additive manufacturing process route is freely designed according to different pore structures, so as to realize the rapid development and manufacture of composite porous absorbent cores. Controllable fabrication of the pore structure can be achieved by changing the process parameters, which can significantly increase the capillary performance while reducing the gas-liquid flow resistance.

The micro-nano pore size formed according to the existing additive manufacturing method is 0.5-200 μm, and the porosity is 5-90%. The pore size and porosity can be realized by controlling the 3D printing process, and the pore size and porosity of the micro-nano pore structure are accurate. It is controllable and overcomes the shortcomings of the existing composite absorbent core manufacturing.

The porous absorbent core manufactured in the present invention can be controlled by laser parameters, and can realize controllable manufacture of surface wettability while constructing a composite gradient pore structure. The hydrophilic surface increases the heat transfer limit of the wick, while the hydrophobic surface enhances condensation, which comprehensively improves the heat transfer efficiency of the heat pipe or vapor chamber.

It should be noted that the above list is only a number of specific embodiments of the present invention, and it is obvious that the present invention is not limited to the above embodiments, and other modifications are also possible. All modifications directly or indirectly derived from the disclosure of the present invention by those skilled in the art should be considered as the protection scope of the present invention.

Claims (7)

1. a manufacture method of composite porous structure liquid-absorbing core, is characterized in that, comprises the following steps: (1) Design a three-dimensional skeleton structure model; (2) Import the designed 3D skeleton structure model into the 3D printing system, use metal powder as raw material, use the laser sintering process to print, and control the laser power, scanning speed, scanning distance and powder layer thickness to obtain micron pores The absorbent core skeleton structure; (3) After printing, oxygen is introduced into the printer cavity, and the oxygen content is 2%-16%; (4) Adjust the laser parameters of the printer, and perform surface laser printing on the skeleton structure of the absorbent core containing micro-pores after printing; (5) Repeating step (4) 2 to 10 times to form an orderly micro-nano pore structure on the surface of the liquid absorbent core, so as to control the hydrophilicity and hydrophobicity of the surface of the composite porous liquid absorbent core. 2 . The method for manufacturing a composite porous structure liquid absorbent core according to claim 1 , wherein the metal powder is 10-80 μm. 3 . 3 . The manufacturing method of the composite porous structure liquid absorbent core according to claim 1 , wherein the laser power is 140-2000 W, the scanning speed is 2000-4000 mm/s, and the printing powder layer thickness is 0.1-1 mm. 4 . 4. The manufacturing method of the composite porous structure liquid absorbent core according to claim 1, characterized in that, in the laser sintering process, the laser sweep rotation angle is 90°, the scanning distance is 0.1mm to 1.2mm, and the powder is laid layer by layer. , and perform a unidirectional cross-line scan. 5 . The manufacturing method of the composite porous structure liquid-absorbent core according to claim 1 , wherein the micro-nanopore size in the liquid-absorbent core is 0.5-200 μm, and the porosity is controlled to be 5%-90%. 6 . 6 . The manufacturing method of the composite porous structure liquid-absorbent core according to claim 1 , wherein the overall thickness of the composite porous structure liquid-absorbent core is 0.1-6 mm. 7 . 7. The manufacturing method of the composite porous structure liquid absorbent core according to claim 1, wherein in step (4), the 3D printing laser power is 5-100W, the scanning speed is 5-200mm/s, and the laser pulse frequency is 10-100W. 100kHz, scanning spacing 0.01 ~ 0.1mm.

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