Sintering-free capillary core porous structure and preparation method thereof
Through the method of segmented electrodeposition and superhydrophilic treatment, the problem of insufficient mechanical strength of the porous structure of capillary cores is solved, and efficient preparation without high-temperature sintering is achieved, simplifying the process and reducing costs, while maintaining excellent capillary performance and boiling heat transfer ability.
Patent Information
- Application Number
- CN202510643262.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-19
- Publication Date
- 2025-08-08
AI Technical Summary
The mechanical strength of the capillary porous structure prepared by the existing hydrogen bubble template method is insufficient, resulting in a decrease in service life and reliability of the heat pipe, requiring high-temperature sintering and reinforcement, and the process is complex and costly.
The segmented electrodeposition method is adopted, high current short-term electrodeposition is performed first, and low current long-term electrodeposition is performed, which increases the copper dendrites coarsing process, and combines superhydrophilic treatment to form a multi-scale pore structure to avoid high-temperature annealing and reinforcement.
The capillary core with excellent mechanical properties is prepared, which simplifies the process flow and reduces the preparation cost, while maintaining high capillary performance and boiling heat transfer capabilities.
Smart Images
Figure CN120443289A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of phase change heat transfer, and in particular relates to a capillary wick porous structure that does not require sintering and a preparation method thereof. Background Art
[0002] With the widespread adoption of electronic technology across various industries and the booming semiconductor technology, chips and power devices are being widely used in fields such as transportation and information technology. New power equipment is developing towards miniaturization, high integration, and high power, but this also poses challenges to the safety and reliability of electronic devices. Temperature issues are one of the main causes of electronic component failure. Research shows that a chip's lifespan is halved for every 10°C increase in temperature. Therefore, achieving more reliable and efficient heat dissipation has become a widespread concern in the electronics industry.
[0003] A heat spreader is a flat-plate heat pipe that is energy-saving and environmentally friendly, has low thermal resistance, and high temperature uniformity. It is an effective means of dissipating heat from electronic devices. A heat spreader is usually made of copper, and its structure includes a vacuum cavity with a microstructure on the inner wall. The cavity is filled with a cooling medium, where the microstructure is a capillary wick. The capillary wick is the core component of the heat spreader. After the medium inside the cavity condenses at the condensation end, it returns to the evaporation end through the capillary action of the capillary wick to continue absorbing heat. Strengthening the capillary performance and boiling performance around the capillary wick surface structure is a major direction for improving the performance of the heat spreader. Currently, the traditional processing methods for the capillary wick structure mainly include: powder sintering, cutting groove forming, and wire mesh sintering. The sintered powder type is to sinter the metal powder directly on the inner wall of the plate, which can provide a larger capillary force, but the permeability is poor. Cutting groove forming is to process grooves on the wall of the uniform temperature plate as reflux channels to reduce flow resistance, but the preparation process is complex and the cost is high; wire mesh sintering forming is to sinter the wire mesh on the inner wall of the plate. The pores of the wire mesh can be controlled. It has the advantages of simple structure, easy manufacturing and low cost. The disadvantage is that there are gaps between the mesh layers and between the wire mesh and the tube wall, which leads to large thermal resistance.
[0004] Compared with the above-mentioned traditional methods, the hydrogen bubble template method can prepare porous copper surface structures with excellent capillary properties, which has the advantages of simplicity, greenness, low cost, and high performance. However, the porous copper surface structures currently prepared by the hydrogen bubble template method have the problem of insufficient mechanical strength, which easily causes the service life and reliability of the heat pipe to decrease, and often requires high-temperature sintering to strengthen the structure. Summary of the Invention
[0005] In order to solve the above technical problems, the present invention provides a capillary wick porous structure that does not require sintering and a preparation method thereof. By adopting segmented electrodeposition, a small current and long-term electrodeposition process is added to the original process to coarsen the copper dendrites, thereby strengthening the capillary wick structure. The prepared capillary wick has excellent mechanical properties and does not require high-temperature annealing to strengthen the capillary wick.
[0006] The present invention is specifically implemented through the following technical solutions.
[0007] The present invention provides a method for preparing a capillary wick porous structure without sintering, comprising the following steps: The copper substrate is polished and cleaned to obtain a pretreated copper substrate.
[0008] The copper substrate is used as the cathode, the copper plate is used as the anode, and the insulating tape and the insulating plate are used as the electroplating shielding material. They are placed in an electrolyte and subjected to segmented electroplating treatment under direct current of given temperature, current density and current time. The segmented electroplating treatment is as follows: first, the first segment of electroplating is performed, and then the second segment of electroplating is performed, and the current density in the first segment of electroplating is greater than the current density in the second segment of electroplating, and the deposition time in the first segment of electroplating is less than the deposition time in the second segment of electroplating.
[0009] Preferably, the current density in the first stage of electrodeposition is in the range of 0.2 A / cm 2 ~1.5A / cm 2 , the total deposition time ranges from 30s to 90s.
[0010] The current density in the second stage of electrodeposition was in the range of 0.001 A / cm 2 ~0.1 A / cm 2 The total deposition time ranges from 2400s to 10800s. Further preferably, the current density in the second stage of electrodeposition is in the range of 0.02A / cm 2 ~0.06A / cm 2 , the total deposition time ranges from 40min to 120min.
[0011] Preferably, the electrolyte is an aqueous solution containing sulfuric acid and copper sulfate, wherein the concentration of sulfuric acid is 0.5 mol / L to 2.5 mol / L, and the concentration of copper sulfate is 0.2 mol / L to 0.5 mol / L.
[0012] Preferably, the temperature during the first and second electrodeposition stages is 10° C. to 35° C.
[0013] Due to the high porosity and large specific surface area of the electrodeposited capillary wick, the surface of the capillary wick is easily oxidized to form highly hydrophobic cuprous oxide, causing the capillary wick to lose its wicking ability. To solve this problem, the present invention performs a super-hydrophilic treatment on the capillary wick after electrodeposition to form a hydrophilic cupric oxide surface on the capillary wick. The prepared capillary wick has multi-scale pores formed by structures such as micropores, nanograss, and nanoflowers. It still has hydrophilic properties after long-term exposure to air, and has excellent capillary properties and boiling heat transfer capabilities.
[0014] Preferably, the copper substrate after electrodeposition is placed in an oxidizing solution for super-hydrophilic treatment, so that the capillary wick forms a hydrophilic copper oxide surface and a scale pore structure grows on the surface of the copper substrate.
[0015] Preferably, the oxidizing solution is an aqueous solution containing sodium hydroxide and ammonium persulfate, wherein the concentration of sodium hydroxide is 1 mol / L to 3 mol / L, and the concentration of ammonium persulfate is in the range of 0.05 mol / L to 0.2 mol / L.
[0016] Preferably, during the superhydrophilic treatment, the temperature is 50° C. to 80° C., and the time is 40 min to 120 min.
[0017] Preferably, the copper substrate material is red copper or pure copper.
[0018] The present invention also provides a capillary wick porous structure, which is prepared by the above preparation method.
[0019] The capillary wick porous structure is a multi-scale pore structure, including micropores, nanograss and nanoflower structures.
[0020] Compared with the prior art, the present invention has the following beneficial effects: The present invention adopts the hydrogen bubble template method to prepare the capillary wick structure, and uses the sample as the cathode. Under the action of the potential difference, the copper ions move toward the cathode, forming a micron-scale copper dendrite structure on the sample surface. During the growth of the dendrite, some hydrogen ions obtain electrons to generate hydrogen bubbles, so that the electrodeposition surface forms a honeycomb porous structure. The capillary wick prepared by the traditional hydrogen bubble template method is relatively fragile and often requires high-temperature annealing to strengthen the structural strength, which prolongs the capillary wick preparation process and makes the process more complicated. The present invention adopts segmented electrodeposition, first performing the first segment of electrodeposition, and then performing the second segment of electrodeposition. The current density in the first segment of electrodeposition is greater than the current density in the second segment of electrodeposition, and the deposition time in the first segment of electrodeposition is less than the deposition time in the second segment of electrodeposition. By adding a small current and long time of electrodeposition process to the original process, the copper dendrite is coarsened, and then the capillary wick structure is reinforced. The prepared capillary wick has excellent mechanical properties, does not require high-temperature annealing to reinforce the capillary wick, simplifies the steps of preparing the copper capillary wick by the hydrogen bubble template method, and saves production costs. Compared with copper powder sintering and wire mesh sintering methods, the hydrogen bubble template method of the present invention has a multi-scale microstructure, a simple process, a low preparation cost, and a shorter preparation time.
[0021] Due to the high porosity and large specific surface area of the electrodeposited capillary wick, the surface of the capillary wick is easily oxidized to form highly hydrophobic cuprous oxide, causing the capillary wick to lose its wicking ability. To solve this problem, the present invention performs a super-hydrophilic treatment on the capillary wick after electrodeposition to form a hydrophilic cupric oxide surface on the capillary wick. The prepared capillary wick has multi-scale pores formed by structures such as micropores, nanograss, and nanoflowers. It still has hydrophilic properties after long-term exposure to air, and has excellent capillary properties and boiling heat transfer capabilities. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 In the figure, (a) and (b) are morphology images of the sample without superhydrophilic treatment in Example 1 at different magnifications.
[0023] Figure 2 This is the sample morphology after super-hydrophilic treatment in Example 2.
[0024] Figure 3 In the figure, (a) and (b) are morphology images of the sample prepared by traditional electrodeposition and without sintering treatment in comparative example 2 at different magnifications.
[0025] Figure 4 This is the morphology of the sample prepared by traditional electrodeposition and sintering treatment in Comparative Example 1.
[0026] Figure 5 This is the morphology of the sample prepared by traditional electrodeposition, sintering treatment and super hydrophilic treatment in comparative example 3. DETAILED DESCRIPTION
[0027] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention is further described below with reference to specific examples and accompanying drawings. However, the examples are not intended to limit the present invention. The experimental methods and detection methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.
[0028] Example 1 A method for preparing a capillary wick porous structure without sintering comprises the following steps: Step 1: Cleaning the copper sheet: polish the copper substrate using 400-grit and 2000-grit sandpaper in sequence, and ultrasonically clean the copper substrate using acetone and ethanol deionized water to remove impurities on the surface of the copper substrate.
[0029] Step 2, deposition: copper substrate as cathode, copper plate as anode, electrical tape and fiberglass board as electroplating shielding materials, put into the electrolyte with sulfuric acid concentration of 1.8mol / L and copper sulfate concentration of 0.4mol / L, the solvent is water, at 20℃, the first section current density is 1A / cm 2 , time 90s, second section current density 0.05A / cm 2 , and segmented electrodeposition treatment was carried out under direct current for 9000s.
[0030] Example 2 A method for preparing a capillary wick porous structure without sintering, compared with Example 1, is subjected to super-hydrophilic treatment, comprising the following steps: Step 1: Cleaning the copper sheet: polish the copper substrate using 400-grit and 2000-grit sandpaper in sequence, and ultrasonically clean the copper substrate using acetone and ethanol deionized water to remove impurities on the surface of the copper substrate.
[0031] Step 2, deposition: copper substrate as cathode, copper plate as anode, electrical tape and fiberglass board as electroplating shielding materials, put into the electrolyte with sulfuric acid concentration of 1.8mol / L and copper sulfate concentration of 0.4mol / L, the solvent is water, at 20℃, the first section current density is 1A / cm 2 , time 90s, second section current density 0.05A / cm 2 , and segmented electrodeposition treatment was carried out under direct current for 9000s.
[0032] Step 3: Superhydrophilic treatment: Place the electrodeposited sample in a 65°C aqueous solution of 2.5 mol / L sodium hydroxide and 0.065 mol / L ammonium persulfate for 60 min. After the sample is taken out, rinse it with ultrapure water and dry it naturally.
[0033] Comparative Example 1 Compared with Example 1, a conventional electrodeposition method is adopted, and subsequent sintering reinforcement is performed. Specifically, during the electrodeposition process, segmented electrodeposition is not adopted, that is, the second low-current electrodeposition process is not performed. The specific steps are as follows: Step 1: Cleaning the copper sheet: polish the copper substrate using 400-grit and 2000-grit sandpaper in sequence, and ultrasonically clean the copper substrate using acetone and ethanol deionized water to remove impurities on the surface of the copper substrate.
[0034] Step 2: Deposition: Use the copper substrate as cathode, the copper plate as anode, the electrical tape and the fiberglass board as electroplating shielding materials, and place them in an electrolyte with a sulfuric acid concentration of 1.8 mol / L and a copper sulfate concentration of 0.4 mol / L at 20°C and a current density of 1 A / cm 2 , and segmented electrodeposition treatment was carried out under direct current for 90s.
[0035] Step 3: Place the deposited sample in a sintering furnace, introduce a reducing gas of 95% nitrogen and 5% hydrogen, and sinter at 740°C for 20 min to enhance the mechanical properties.
[0036] Comparative Example 2 Compared with Comparative Example 1, no sintering treatment was performed, and the specific steps were as follows: Step 1: Cleaning the copper sheet: polish the copper substrate using 400-grit and 2000-grit sandpaper in sequence, and ultrasonically clean the copper substrate using acetone and ethanol deionized water to remove impurities on the surface of the copper substrate.
[0037] Step 2: Deposition: Use the copper substrate as cathode, the copper plate as anode, the electrical tape and the fiberglass board as electroplating shielding materials, and place them in an electrolyte with a sulfuric acid concentration of 1.8 mol / L and a copper sulfate concentration of 0.4 mol / L at 20°C and a current density of 1 A / cm 2 , and segmented electrodeposition treatment was carried out under direct current for 90s.
[0038] Comparative Example 3 Compared with Comparative Example 1, a super-hydrophilic treatment was further performed, comprising the following steps: Step 1: Cleaning the copper sheet: polish the copper substrate using 400-grit and 2000-grit sandpaper in sequence, and ultrasonically clean the copper substrate using acetone and ethanol deionized water to remove impurities on the surface of the copper substrate.
[0039] Step 2: Deposition: Use the copper substrate as cathode, the copper plate as anode, the electrical tape and the fiberglass board as electroplating shielding materials, and place them in an electrolyte with a sulfuric acid concentration of 1.8 mol / L and a copper sulfate concentration of 0.4 mol / L at 20°C and a current density of 1 A / cm 2 , and segmented electrodeposition treatment was carried out under direct current for 90s.
[0040] Step 3: Place the deposited sample in a sintering furnace, introduce a reducing gas of 95% nitrogen and 5% hydrogen, and sinter at 740 °C for 20 min to enhance the mechanical properties.
[0041] Step 4: Superhydrophilic treatment: Place the electrodeposited sample in a 65°C aqueous solution of 2.5 mol / L sodium hydroxide and 0.065 mol / L ammonium persulfate for 60 min. After the sample is taken out, rinse it with ultrapure water and dry it naturally.
[0042] To compare the mechanical strength of electrodeposited capillary wicks produced using different processes, the capillary wicks prepared in Example 1, Comparative Example 1, and Comparative Example 2 were ultrasonically cleaned in alcohol for one minute. The weight change before and after ultrasonic cleaning was measured using an electronic analytical balance. The ultrasonic cleaning machine used was a ZX-040S, operating at a frequency of 40 kHz. The results are shown in Table 1.
[0043] Table 1 Weight change data of each group of samples before and after ultrasound As can be seen from Table 1 above, the conventional process of Comparative Example 1 only has the first electrodeposition process, followed by sintering reinforcement, and the mass loss is 0.980%. However, after adopting the method of the present invention and adding a period of long-term electrodeposition process with a small current, the weight loss rate of the sample prepared in Example 1 is 0.331%, which is lower than that of Comparative Example 1. This shows that the method of the present invention, without sintering treatment, can not only ensure a low mass loss, that is, excellent mechanical strength, but also omit the sintering step and simplify the preparation process. Comparative Example 2 uses conventional deposition but does not perform sintering treatment, and its weight loss is the largest, at 90.566%. This shows that when using the conventional electrodeposition method, sintering reinforcement is required to obtain a capillary wick porous structure with high mechanical strength.
[0044] Figure 3 In the figure, (a) and (b) show the morphology of the sample prepared by traditional electrodeposition and without sintering treatment at different magnifications in Comparative Example 2. It can be seen that without the second stage of low-current reinforcement, the dendrites are thinner, the inter-dendritic connections are less, and the mechanical strength is poor. Figure 4 This is the morphology of the sample prepared by conventional electrodeposition and sintering in Comparative Example 1. Figure 3 In comparison, copper dendrites are coarsened after sintering and are connected to each other under the softening effect of high-temperature sintering, so the mechanical properties are better. Figure 1 In the figure, (a) and (b) are the morphology images of the sample without super-hydrophilic treatment in Example 1 at different magnifications. Figure 3 In contrast, the dendrites are somewhat coarsened and interconnected, which strengthens the mechanical properties of the electrodeposited copper surface structure. This corresponds to the weight loss data in Table 1 and also explains the difference in mechanical properties shown in Table 1.
[0045] Figure 2 This is the topography of the sample from Example 2 after superhydrophilic treatment. It can be seen that the surface has micropores with a diameter of approximately 100 μm. After superhydrophilic treatment, nanograss and nanoflower structures with a size of approximately 100 nm are present on the pore walls. During superhydrophilic treatment, the relatively coarse dendrite structure favors the formation of copper oxide nanoflowers and nanograss structures. In other words, the present invention initially uses segmented electrodeposition to coarsen the dendrites, improving the mechanical properties of the porous capillary wick structure and also facilitating the formation of copper oxide nanoflowers and nanograss structures during subsequent superhydrophilic treatment.
[0046] Figure 5 The morphology of the samples prepared by traditional electrodeposition, sintering, and superhydrophilic treatment in Comparative Example 3 is shown. It can be seen that for traditional sintering electrodeposition, the dendrite structure is relatively small during superhydrophilic treatment, making it difficult to form nanoflower or nanograss-like copper oxide structures on the surface.
[0047] Example 3 A method for preparing a capillary wick porous structure without sintering, characterized by comprising the following steps: Step 1: Cleaning the copper sheet: polish the copper substrate using 400-grit and 2000-grit sandpaper in sequence, and ultrasonically clean the copper substrate using acetone and ethanol deionized water to remove impurities on the surface of the copper substrate.
[0048] Step 2: Deposition: Use the copper substrate as cathode, the copper plate as anode, the electrical tape and the fiberglass board as electroplating shielding materials, and place them in an electrolyte with a sulfuric acid concentration of 1.8 mol / L and a copper sulfate concentration of 0.4 mol / L. At 20°C, the first current density is 1A / cm 2 , time 90 s, second stage current density 0.02 A / cm 2 , and segmented electrodeposition treatment was carried out under direct current for 120 minutes.
[0049] Step 3: Superhydrophilic treatment: Place the electrodeposited sample in a 65°C aqueous solution of 2.5 mol / L sodium hydroxide and 0.065 mol / L ammonium persulfate for 60 min. After the sample is taken out, rinse it with ultrapure water and dry it naturally.
[0050] Example 4 A method for preparing a capillary wick porous structure without sintering, characterized by comprising the following steps: Step 1: Cleaning the copper sheet: polish the copper substrate using 400-grit and 2000-grit sandpaper in sequence, and ultrasonically clean the copper substrate using acetone and ethanol deionized water to remove impurities on the surface of the copper substrate.
[0051] Step 2, deposition: With the copper substrate as cathode, the copper plate as anode, the electrical tape and the fiberglass board as electroplating shielding materials, put them into the electrolyte with sulfuric acid concentration of 1.8 mol / L and copper sulfate concentration of 0.4 mol / L, at 15 ° C, the first current density is 1A / cm 2 , time 90 s, second stage current density 0.06 A / cm 2 , and segmented electrodeposition treatment was carried out under direct current for 100 minutes.
[0052] Step 3: Superhydrophilic treatment: Place the electrodeposited sample in a 65°C aqueous solution of 2.5 mol / L sodium hydroxide and 0.065 mol / L ammonium persulfate for 60 min. After the sample is taken out, rinse it with ultrapure water and dry it naturally.
[0053] Example 5 A method for preparing a capillary wick porous structure without sintering, characterized by comprising the following steps: Step 1: Cleaning the copper sheet: polish the copper substrate using 400-grit and 2000-grit sandpaper in sequence, and ultrasonically clean the copper substrate using acetone and ethanol deionized water to remove impurities on the surface of the copper substrate.
[0054] Step 2, deposition: With the copper substrate as cathode, the copper plate as anode, the electrical tape and the fiberglass board as electroplating shielding materials, put them into the electrolyte with sulfuric acid concentration of 1.8 mol / L and copper sulfate concentration of 0.4 mol / L, at 15 ° C, the first current density is 0.2 A / cm 2 , time 90 s, second stage current density 0.05 A / cm 2 , and segmented electrodeposition treatment was carried out under direct current of 9000 s.
[0055] Step 3: Superhydrophilic treatment: Place the electrodeposited sample in a 65°C aqueous solution of 2.5 mol / L sodium hydroxide and 0.065 mol / L ammonium persulfate for 60 min. After the sample is taken out, rinse it with ultrapure water and dry it naturally.
[0056] Example 6 A method for preparing a capillary wick porous structure without sintering, characterized by comprising the following steps: Step 1: Cleaning the copper sheet: polish the copper substrate using 400-grit and 2000-grit sandpaper in sequence, and ultrasonically clean the copper substrate using acetone and ethanol deionized water to remove impurities on the surface of the copper substrate.
[0057] Step 2, deposition: With the copper substrate as cathode, the copper plate as anode, the electrical tape and the fiberglass board as electroplating shielding materials, put them into the electrolyte with a sulfuric acid concentration of 1.8 mol / L and a copper sulfate concentration of 0.4 mol / L, at 15 ° C, the first section current density is 1.5 A / cm2 , time 30 s, second stage current density 0.05 A / cm 2 , and segmented electrodeposition treatment was carried out under direct current of 9000 s.
[0058] Step 3: Superhydrophilic treatment: Place the electrodeposited sample in a 65°C aqueous solution of 2.5 mol / L sodium hydroxide and 0.065 mol / L ammonium persulfate for 60 min. After the sample is taken out, rinse it with ultrapure water and dry it naturally.
[0059] Example 7 A method for preparing a capillary wick porous structure without sintering, characterized by comprising the following steps: Step 1: Cleaning the copper sheet: polish the copper substrate using 400-grit and 2000-grit sandpaper in sequence, and ultrasonically clean the copper substrate using acetone and ethanol deionized water to remove impurities on the surface of the copper substrate.
[0060] Step 2, deposition: With the copper substrate as cathode, the copper plate as anode, the electrical tape and the fiberglass board as electroplating shielding materials, put them into the electrolyte with sulfuric acid concentration of 1.8 mol / L and copper sulfate concentration of 0.4 mol / L, at 15 ° C, the first current density is 1A / cm 2 , time 90 s, second stage current density 0.05 A / cm 2 , and segmented electrodeposition treatment was carried out under direct current of 9000 s.
[0061] Step 3: Superhydrophilic treatment: Place the electrodeposited sample in a 65°C aqueous solution of 1 mol / L sodium hydroxide and 0.2 mol / L ammonium persulfate for 60 min. After the sample is taken out, rinse it with ultrapure water and dry it naturally.
[0062] Example 8 A method for preparing a capillary wick porous structure without sintering, characterized by comprising the following steps: Step 1: Cleaning the copper sheet: polish the copper substrate using 400-grit and 2000-grit sandpaper in sequence, and ultrasonically clean the copper substrate using acetone and ethanol deionized water to remove impurities on the surface of the copper substrate.
[0063] Step 2, deposition: With the copper substrate as cathode, the copper plate as anode, the electrical tape and the fiberglass board as electroplating shielding materials, put them into the electrolyte with sulfuric acid concentration of 1.8 mol / L and copper sulfate concentration of 0.4 mol / L, at 15 ° C, the first current density is 1A / cm 2 , time 90 s, second stage current density 0.05 A / cm 2 , and segmented electrodeposition treatment was carried out under direct current of 9000 s.
[0064] Step 3: Superhydrophilic treatment: Place the electrodeposited sample in a 65°C aqueous solution of 3 mol / L sodium hydroxide and 0.05 mol / L ammonium persulfate for 60 min. After the sample is taken out, rinse it with ultrapure water and dry it naturally.
[0065] Example 9 A method for preparing a capillary wick porous structure without sintering, characterized by comprising the following steps: Step 1: Cleaning the copper sheet: polish the copper substrate using 400-grit and 2000-grit sandpaper in sequence, and ultrasonically clean the copper substrate using acetone and ethanol deionized water to remove impurities on the surface of the copper substrate.
[0066] Step 2, deposition: With the copper substrate as cathode, the copper plate as anode, the electrical tape and the fiberglass board as electroplating shielding materials, put them into the electrolyte with sulfuric acid concentration of 1.8 mol / L and copper sulfate concentration of 0.4 mol / L, at 15 ° C, the first current density is 1A / cm 2 , time 90 s, second stage current density 0.05 A / cm 2 , and segmented electrodeposition treatment was carried out under direct current of 9000 s.
[0067] Step 3: Superhydrophilic treatment: Place the electrodeposited sample in a 50°C aqueous solution of 2.5 mol / L sodium hydroxide and 0.065 mol / L ammonium persulfate for 60 min. After the sample is taken out, rinse it with ultrapure water and dry it naturally.
[0068] Example 10 A method for preparing a capillary wick porous structure without sintering, characterized by comprising the following steps: Step 1: Cleaning the copper sheet: polish the copper substrate using 400-grit and 2000-grit sandpaper in sequence, and ultrasonically clean the copper substrate using acetone and ethanol deionized water to remove impurities on the surface of the copper substrate.
[0069] Step 2, deposition: With the copper substrate as cathode, the copper plate as anode, the electrical tape and the fiberglass board as electroplating shielding materials, put them into the electrolyte with sulfuric acid concentration of 1.8 mol / L and copper sulfate concentration of 0.4 mol / L, at 15 ° C, the first current density is 1A / cm 2 , time 90 s, second stage current density 0.05 A / cm 2 , and segmented electrodeposition treatment was carried out under direct current of 9000 s.
[0070] Step 3: Superhydrophilic treatment: Place the electrodeposited sample in an aqueous solution of 2.5 mol / L sodium hydroxide and 0.065 mol / L ammonium persulfate at 80°C for 60 min. After the sample is taken out, wash it with ultrapure water and dry it naturally.
[0071] The samples prepared in Examples 3 to 10 are similar to those in Example 2, and no sintering treatment is required. The prepared samples all have good mechanical properties and can generate copper oxide nanoflowers and copper oxide nanograss structures, which will not be described in detail.
[0072] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications of the present invention fall within the scope of the claims and their equivalents, such changes and modifications are also intended to be included.
Claims
1. A method for preparing a capillary wick porous structure without sintering, characterized in that: The following steps are involved: Polishing and cleaning the copper substrate to obtain a pretreated copper substrate; The pretreated copper substrate is used as the cathode and the copper plate is used as the anode, which are placed in an electrolyte. Under direct current, the first stage of electrodeposition is performed first, and then the second stage of electrodeposition is performed. The current density in the first stage of electrodeposition is greater than the current density in the second stage of electrodeposition, and the deposition time in the first stage of electrodeposition is less than the deposition time in the second stage of electrodeposition.
2. The preparation method according to claim 1, characterized in that The current density in the first stage of electrodeposition was 0.2 A / cm 2 ~1.5A / cm 2 , the total deposition time is 30s~90s; The current density in the second electrodeposition stage was 0.001 A / cm 2 ~0.1 A / cm 2 , the total deposition time is 2400s~10800s.
3. The preparation method according to claim 2, characterized in that The current density in the second electrodeposition stage was 0.02 A / cm 2 ~0.06A / cm 2 The total deposition time is 40min~120min.
4. The preparation method according to claim 1, characterized in that The electrodeposited copper substrate is placed in an oxidizing solution for superhydrophilic treatment, and a multi-scale pore structure is grown on the surface of the copper substrate.
5. The preparation method according to claim 4, characterized in that The oxidizing solution is an aqueous solution containing sodium hydroxide and ammonium persulfate, wherein the concentration of sodium hydroxide is 1 mol / L~3 mol / L, and the concentration of ammonium persulfate is 0.05 mol / L~0.2 mol / L.
6. The preparation method according to claim 4, characterized in that During the superhydrophilic treatment, the temperature is 50℃~80℃ and the time is 40min~120min.
7. The preparation method according to claim 4, characterized in that The multi-scale pore structures include micropores, nanograss and nanoflower structures.
8. The preparation method according to claim 1, characterized in that The electrolyte is an aqueous solution containing sulfuric acid and copper sulfate, wherein the concentration of sulfuric acid is 0.5 mol / L~2.5 mol / L, and the concentration of copper sulfate is 0.2 mol / L~0.5 mol / L.
9. The preparation method according to claim 1, characterized in that During the first and second stages of electrodeposition, the temperature is 10°C to 35°C.
10. A capillary wick porous structure, characterized in that: The preparation method according to any one of claims 1 to 9 is used to prepare the compound.