Two-dimensional nano-aluminum reinforced composite phase change material and preparation method thereof
By attaching two-dimensional nano-aluminum sheets to the surface of graphite or paraffin, a thermal conductivity path is formed and the phase change material is adsorbed in the porous carbon-based material, the compatibility problems in the enhancement of thermal conductivity of phase change materials and the problem of material shape fixation is solved, and a composite phase change material with high thermal conductivity and easy-to-shape is achieved.
Patent Information
- Application Number
- CN202510244179.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-03
- Publication Date
- 2025-06-27
AI Technical Summary
In the existing thermal conductivity enhancement methods of phase change materials, the compatibility problem between fillers and phase change materials leads to agglomeration and precipitation of fillers, making it difficult to exert thermal conductivity. At the same time, the addition of a thermal skeleton makes the shape of the composite material fixed, making it difficult to adapt to the changing scenario requirements.
By attaching two-dimensional nano-aluminum sheets to the surface of graphite or paraffin, a thermal conductivity path is formed, the thermal conductivity of the phase change material is enhanced, and the phase change material is adsorbed through porous carbon-based materials to solve the compatibility problem while maintaining the shapeability of the material.
The thermal conductivity of phase change materials is significantly improved, the aggregation and precipitation of fillers is avoided, and the composite materials are easy to shape and adapt to changing scenario needs.
Smart Images
Figure CN120209782A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of heat conduction enhancing materials, and particularly to a two-dimensional nano-aluminum enhanced composite phase change material and a preparation method thereof. Background Art
[0002] In the prior art, the enhancement of the thermal conductivity of phase change materials is mainly achieved by adding thermal conductive fillers. The forms of thermal conductive fillers are mainly divided into two categories: one is in the form of particles or flakes directly put into the phase change material through a dispersant. The main disadvantage of this form is the compatibility problem between the filler and the phase change material itself. During the phase change process, even with the addition of a dispersant, phase separation is very likely to occur, causing the filler to agglomerate and precipitate, and it is difficult to exert the thermal conductivity of the filler. The other is to add a thermal conductive skeleton. Although this method can avoid the compatibility problem, the skeleton structure makes the shape of the composite material itself fixed and difficult to adapt to the requirements of changing scenarios. Summary of the Invention
[0003] The purpose of the present invention is to provide a two-dimensional nano-aluminum enhanced composite phase change material and a preparation method thereof, which can solve the above technical problems.
[0004] The present invention provides a preparation method of a two-dimensional nano-aluminum enhanced composite phase change material, comprising the following steps:
[0005] Step 1: Coating an isolation coating on a metal aluminum foil substrate;
[0006] Step 2: Folding the metal aluminum foil coated with the isolation coating obtained in Step 1. The folding can be folding in half;
[0007] Step 3: Repeatedly rolling the metal aluminum foil obtained in Step 2. Each time it is rolled, the thickness becomes half of the original thickness, obtaining a product of multiple rollings. Specifically, after folding once, it is rolled multiple times, and each time its thickness becomes 1 / 2 of the original. This process is repeated multiple times (before each rolling, folding is performed. The folding can be in the form of folding in half, stacking, etc., which is not limited here). This process is to continuously extend the metal aluminum and continuously reduce its thickness until the thickness becomes nano-sized.
[0008] Step 4: Dissolving and dispersing the product of multiple rollings obtained in Step 3 in a solvent to remove the isolation coating, and then centrifuging and drying to obtain two-dimensional aluminum nanosheets;
[0009] Step 5: Heating flaky graphite to obtain expanded graphite, and pre-melting and degassing paraffin in a vacuum oven to obtain molten paraffin;
[0010] Step 6: Add the dried two-dimensional aluminum nanosheets and expanded graphite into molten paraffin to form a mixture. Stir the mixture in an oil bath at 70 - 100 °C for 30 - 300 s using a mechanical stirrer to obtain a uniform nAl-EG-PW mixture. Put the mixture into a shaping mold and press it into a block under a pressure of 2 - 12 MPa, where the loading amount of the two-dimensional aluminum nanosheets is 0 - 30 wt%, and the loading amount of the expanded graphite is 0 - 40 wt%.
[0011] Preferably, the isolation coating in Step 1 is one or more of paraffin, asphalt, phenolic resin, polystyrene, polyethylene, polypropylene, polyethylene glycol, polybutadiene, coal tar, polymethyl methacrylate, polyvinyl pyrrolidone, glycerol, oleic acid, polyacrylonitrile, polyvinyl alcohol, cellulose, sucrose.
[0012] In addition, paraffin as the phase change material in Step 5 can also be one or more of phase change materials such as capric acid, lauric acid, palmitic acid, sodium acetate trihydrate, myristic acid, polyethylene glycol, etc. Paraffin can be used as an "isolation material" when rolling to prepare metal nanosheets and as a "phase change material" when preparing phase change composite materials.
[0013] Preferably, the thickness of the aluminum foil in Step 2 is 50 - 2000 μm, and the thickness of the isolation coating coated on the aluminum foil is 2 - 50 μm.
[0014] Preferably, the linear speed of the rolling mill in Step 3 is: 0.25 - 35 mm / s, and the roll spacing is set to: 0.05 mm - 1 mm.
[0015] Preferably, the solvents for dispersing and dissolving the isolation coating in Step 4 are one or more of solvents such as petroleum ether, NMP, isopropanol, gasoline, carbon disulfide, ether, chloroform, carbon tetrachloride, naphtha, acetone, methanol, ethanol, butanol, xylene, benzene, ethyl acetate, etc.
[0016] Preferably, the size of the graphite flakes in Step 5 is 10 mesh - 1000 mesh.
[0017] Preferably, the flaky graphite is heated at 550 °C for 5 h in Step 5 to obtain expanded graphite.
[0018] Preferably, the paraffin is pre-melted and degassed in a vacuum oven at 105 °C for 12 h in Step 5.
[0019] Preferably, the oil bath temperature in Step 6 is 90 °C.
[0020] The present invention also provides a composite phase change material prepared by the above preparation method.
[0021] The beneficial effects of the present invention:
[0022] In the present invention, the phase change material is first adsorbed inside a porous carbon-based material that is easy to shape, and then two-dimensional metal nanosheets are attached to the surface of the framework to form a heat conduction path, thereby enhancing the thermal conductivity of the phase change material, solving the compatibility problem between the filler and the phase change material, and at the same time, the prepared composite phase change material is easy to shape. Compared with the existing methods for enhancing the thermal conductivity of phase change materials by adding fillers, the method in the present invention has the following advantages: First, the process flow of this method is simple, the equipment requirements are low, and it is easy to mass-produce; Second, this method attaches two-dimensional metal nanosheets to the surface of the support material to fit with the material, and this method is original in enhancing the thermal conductivity of phase change materials; Third, the thermal conductivity of the composite phase change material obtained by this method is much higher than that of the composite phase change material obtained by other methods; Fourth, the occurrence of leakage during the phase change process of the composite phase change material obtained by this method is greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0024] Figure 1 It is a process schematic diagram of the preparation method of the present invention;
[0025] Figure 2 It is a SEM image of two-dimensional nano-aluminum in the present invention;
[0026] Figure 3 It is a cross-sectional image of unexpanded graphite in the present invention;
[0027] Figure 4 It is a surface image of expanded graphite in the present invention;
[0028] Figure 5 It is a schematic diagram of expanded graphite after adsorbing paraffin in the present invention;
[0029] Figure 6 It is a schematic diagram of two-dimensional nano-aluminum adhering to the surface of expanded graphite adsorbed with paraffin in the present invention;
[0030] Figure 7 It is a cross-sectional image (8n-Al%) of the sample after removing the internal paraffin at high temperature after die pressing (12 MPa) in the present invention;
[0031] Figure 8 It is a schematic diagram of the distribution of nano-aluminum on the surface of the sample after die pressing (2 MPa) in the present invention;
[0032] Figure 9 Schematic diagram of the sample thermal conductivity results in the present invention;
[0033] Figure 10 Schematic diagram of the AFM data of the metal nanosheet after rolling. Detailed implementation manners
[0034] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs.
[0035] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms also include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0036] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
[0037] Embodiment 1
[0038] A preparation method of a two-dimensional nano-aluminum enhanced composite phase change material, comprising the following steps:
[0039] Coat a paraffin coating with a thickness of about 5 μm on the upper and lower surfaces of a 50-μm-thick aluminum foil. After folding in half or stacking two aluminum foils, place them in a rolling mill with a roll gap of 50 μm for rolling. Then fold the aluminum / paraffin rolled sheet and roll it again. The folding can be folding in half, and each rolling is reduced to 1 / 2 of the original thickness. Roll 18 times to obtain a paraffin-aluminum composite material. Dissolve and disperse the paraffin-aluminum composite material in a petroleum ether solvent to remove the paraffin, and then centrifuge and dry to obtain two-dimensional aluminum nanosheets. The obtained nano-aluminum has a thickness of about 5 nm (specifically visible in the Figure 10 AFM data), and the average radial size is 20 μm.
[0040] Heat 4 g of 50-mesh flaky graphite at 550 °C for 5 h to obtain expanded graphite. Pre-melt and degas paraffin in a vacuum oven (maintained at 105 °C) for 12 hours, and then add the expanded graphite and mix.
[0041] 3.6 g of two-dimensional aluminum nanosheets were added to the mixture of paraffin and expanded graphite, and it was slowly stirred for 120 s using a mechanical stirrer under the condition of an oil bath maintained at 90 °C to obtain a uniform 18Al-EG-PW mixture.
[0042] The mixture was put into a shaping mold and pressed into a block using a pressure of 12 MPa, and the thermal conductivity and leakage rate of the prepared sample were measured.
[0043] Example 2-11
[0044] The operating steps in Example 2-11 were the same as those in Example 1, except that the content of nano-aluminum was different. See the following table:
[0045] n-Al(g) n-Al% <![CDATA[Thermal conductivity Wm -1 K -1 > Leakage rate% Example 1 3.6 18 18.432 3 Example 2 0 0 9.769 12 Example 3 0.4 2 9.769 10 Example 4 0.8 4 10.94 9 Example 5 1.2 6 11.431 7 Example 6 1.6 8 11.75 7 Example 7 2 10 12.595 6 Example 8 2.4 12 14.29 4 Example 9 2.8 14 15.209 4 Example 10 3.2 16 18.15 4 Example 11 4 20 16.87 3
[0046] Examples 12-16
[0047] The operating steps in Examples 12-16 were the same as those in Example 1, except that the content of expanded graphite was different. See the following table:
[0048]
[0049] Examples 17-21
[0050] The operating steps in Examples 17-21 were the same as those in Example 1, except that the size of expanded graphite was different. See the following table:
[0051]
[0052] Examples 22-31
[0053] The operating steps in Examples 22-31 were the same as those in Example 1, except that the mechanical stirring time was different. See the following table:
[0054]
[0055] Comparative Examples 1-3
[0056] The operating steps in Comparative Examples 1-3 were the same as those in Example 1, except that the two-dimensional nano-aluminum in the experiment was replaced with spherical aluminum powder of 500 mesh. See the following table:
[0057] Aluminum powder (g) Aluminum powder% <![CDATA[Thermal conductivity Wm -1 K -1 > Leakage rate% Comparative Example 1 1.2 6 10.256 12 Comparative Example 2 2.4 12 10.795 10 Comparative Example 3 3.6 18 11.157 9
[0058] The operating steps in Example 2-11 were the same as those in Example 1, except that the content of nano-aluminum was different. It can be seen that a suitable content of nano-aluminum will have the highest thermal conductivity and the lowest leakage rate.
[0059] Examples 12 - 16 have the same operation steps as Example 1, except for the different contents of expanded graphite. It can be seen that a suitable content of expanded graphite will have the highest thermal conductivity and the lowest leakage rate.
[0060] Examples 17 - 21 have the same operation steps as Example 1, except for the different sizes of expanded graphite. It can be seen that a suitable size of expanded graphite will have the highest thermal conductivity and the lowest leakage rate.
[0061] Examples 22 - 31 have the same operation steps as Example 1, except for the different mechanical stirring times. It can be seen that a suitable mechanical stirring time will have the highest thermal conductivity and the lowest leakage rate.
[0062] Comparative Examples 1 - 3 have the same operation steps as Example 1, except that the two - dimensional nano - aluminum in the experiment is replaced with spherical aluminum powder of 500 meshes. It can be seen that the two - dimensional nano - structure has a more obvious increase in the thermal conductivity of the phase - change material and a lower leakage rate compared with the spherical particle structure.
[0063] The composite phase - change material is characterized in that: First, the addition of two - dimensional nano - metal sheets can form new heat - conduction paths inside the phase - change material, greatly enhancing the thermal conductivity of the composite phase - change material without reacting with the phase - change material and affecting the high - heat - enthalpy characteristics of the phase - change material itself; Second, the support material itself has dense cavities, which can well adsorb the phase - change material inside the support material through capillary action. While further enhancing the heat - conduction performance of the phase - change material, it can also prevent the liquid leakage of the phase - change material during the phase - change process. The present invention has a better effect than the traditional method of directly adding metal particles or encapsulating the phase - change material.
[0064] Finally, it should be noted that: The above - mentioned embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: They can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; And these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for preparing a two-dimensional nano-aluminum reinforced composite phase change material, characterized in that The following steps are involved: Step 1: Applying the isolation coating onto the metal aluminum foil substrate; Step 2: folding the metal aluminum foil coated with the isolation coating obtained in step 1; Step 3: Repeatedly rolling the metal aluminum foil obtained in step 2, wherein the thickness becomes half of the original thickness each time the rolling is performed, and a multi-rolled product is obtained; Step 4: dissolving and dispersing the multiple rolling products obtained in step 3 in a solvent to remove the isolation coating, and then centrifugally drying to obtain two-dimensional aluminum nanosheets; Step 5: heating the flake graphite to obtain expanded graphite, and pre-melting and degassing the paraffin in a vacuum oven to obtain molten paraffin; Step 6: Add the dried two-dimensional aluminum nanosheets and expanded graphite to the molten paraffin to form a mixture, stir it with a mechanical stirrer under oil bath conditions to obtain a uniform nAl-EG-PW mixture, and put the mixture into a shaping mold and press it into a block using a pressure of 2-12 MPa.
2. The preparation method according to claim 1, characterized in that: The isolation coating in step 1 is one or more of paraffin, asphalt, phenolic resin, polystyrene, polyethylene, polypropylene, polyethylene glycol, polybutadiene, coal tar, polymethyl methacrylate, polyvinyl pyrrolidone, glycerol, oleic acid, polyacrylonitrile, polyvinyl alcohol, cellulose, and sucrose.
3. The preparation method according to claim 1, characterized in that: In the step 2, the thickness of the aluminum foil is 50-2000 μm, and the thickness of the isolation coating applied on the aluminum foil is 2-50 μm.
4. The preparation method according to claim 1, characterized in that: In step 3, the linear speed of the rollers is 0.25-35 mm / s, and the roller spacing is set to 0.05 mm-1 mm.
5. The preparation method according to claim 1, characterized in that: The solvent for dispersing and dissolving the isolation coating in step 4 is one or more of petroleum ether, NMP, isopropanol, gasoline, carbon disulfide, ether, chloroform, carbon tetrachloride, naphtha, acetone, methanol, ethanol, butanol, xylene, benzene, and ethyl acetate.
6. The preparation method according to claim 1, characterized in that: The size of the graphite sheet in step 5 is 10 mesh to 1000 mesh.
7. The preparation method according to claim 1, characterized in that: In the step 5, the flake graphite is heated at 550° C. for 5 hours to obtain expanded graphite.
8. The preparation method according to claim 1, characterized in that: In step 5, the paraffin is maintained in a vacuum oven at 105° C. for pre-melting and degassing for 12 hours.
9. The preparation method according to claim 1, characterized in that: The oil bath temperature in step 6 is 90°C.
10. The composite phase change material prepared according to the preparation method according to any one of claims 1 to 9.