Thin film coating for strengthening heat dissipation capability of device and preparation method of thin film coating
By introducing carbon nanotubes and sodium alginate crosslinked calcium chloride to encapsulated hydrated salts, the problem of insufficient thermal resistance and phase change material enthalpy value of fin radiator is solved, and efficient heat dissipation capacity and temperature reduction is achieved, which is suitable for the heat dissipation management of electronic equipment.
Patent Information
- Application Number
- CN202510522559.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-24
- Publication Date
- 2025-07-18
AI Technical Summary
Existing passive thermal management methods such as fin radiators have problems in introducing thermal resistance and reaching the limit when processing heat from electronic equipment, especially the enthalpy value of phase change materials is too small and the thermal resistance increases, resulting in poor heat dissipation effect.
By introducing carbon nanotubes into the coating, the thermal conductivity and radiation capacity is enhanced, and the hydrating salts are encapsulated with sodium alginate cross-linked calcium chloride to achieve hygroscopic absorption and phase change materials during the phase change process, avoiding the increase in thermal resistance, and a thin film coating with enhanced thermal conductivity and radiation capacity is prepared.
Effectively reduce device temperature, reduce thermal resistance, improve heat dissipation ability, and achieve long-term and stable cooling effect. The preparation process is simple, environmentally friendly and harmless, suitable for industrial production.
Smart Images
Figure CN120329796A_ABST
Abstract
Description
Technical Field
[0001] The design of the present invention belongs to the field of heat dissipation materials, and specifically relates to a heat dissipation enhanced coating that combines the moisture absorption of calcium chloride and the enhanced heat conduction and radiation of carbon nanotubes. Background Art
[0002] With the continuous update and iteration of electronic technology, products are constantly developing towards miniaturization and integration, which has also caused a substantial increase in the heat generation of electronic devices. Excessive heat accumulation inside will seriously affect the service life and safety of the devices, and may even lead to fire or explosion. Therefore, using appropriate thermal management means to handle heat generation is extremely important for improving the operating stability and performance of the devices. Common thermal management means are usually divided into active and passive types. Passive thermal management means are more widely used because they do not require additional energy input. Among them, fins are the most common passive solution, and currently, improving the heat dissipation capacity of fins by modifying the structure has reached the design limit, and a larger area will also cause space and resource occupation. Therefore, the heat dissipation capacity can be enhanced by combining phase change with fin radiators.
[0003] The methods of phase change usually include solid-liquid and liquid-gas phase changes. Common phase change materials such as paraffin and polyethylene glycol undergo solid-liquid phase changes, but their phase change enthalpy values are too small to carry away much heat. The liquid-gas phase change of water, as a common phase change process, has a huge enthalpy value and can carry away sufficient heat. Therefore, we add a liquid-gas phase change of water to the heat dissipation process by means of a moisture absorption coating surface of polymer-encapsulated deliquescent salts to slow down the temperature rise curve. Existing moisture absorption and heat dissipation means, such as the paper "Passive thermal management of electronic devices using sorption-based evaporative cooling", use porous media such as felt pads to load moisture absorption salts to meet the intermittent heat dissipation means. However, this cannot avoid introducing new thermal resistance, and when the liquid is exhausted, it will lead to a deterioration of the heat dissipation situation, which is even worse than the bare board surface.
[0004] In order to reduce the thermal resistance introduced on the coating surface, we add carbon nanotubes to increase heat conduction and radiation to effectively enhance the heat dissipation capacity in the long term and reduce the device temperature. Summary of the Invention
[0005] The purpose of the present invention is to provide a heat dissipation coating for enhancing the heat dissipation capacity of devices and its preparation method. The present invention can utilize the phase change process on the surface of the radiator to carry away heat, and at the same time, carbon nanotubes can enhance the heat conduction and radiation capabilities to reduce the device temperature in the long term.
[0006] The present invention provides a heat dissipation enhancement coating with enhanced heat conduction and radiation capabilities and capable of undergoing a phase change process on the surface, and a preparation method thereof. The specific solution is to encapsulate deliquescent salts with a substrate material and a cross-linking agent so that they can absorb moisture in the air to create a phase change process without leakage, and heat conduction and radiation enhancement materials are heated in the substrate material to stably cool down for a long time. The use of an adhesive and a modifier can make the coating adhere tightly to the surface of the heat dissipation device.
[0007] A preparation method of a thin film coating for enhancing the heat dissipation ability of a device is as follows
[0008] (1) Pretreat the substrate: Clean and dry the substrate material to obtain a pretreated substrate material.
[0009] (2) Prepare the substrate coating: Add polyvinyl alcohol particles to water, stir to obtain solution A, then add sodium alginate to solution A, stir to obtain solution B, add carbon nanomaterials to solution B, and ultrasonically obtain a uniformly dispersed suspension C of carbon nanomaterials as the substrate coating; the mass ratio of carbon nanomaterials, polyvinyl alcohol, sodium alginate, and water is (0.05 - 0.2):(2 - 8):(1 - 4):100.
[0010] (3) Prepare the cross-linking material: Add anhydrous calcium chloride to water and stir to obtain a calcium chloride solution as the cross-linking agent.
[0011] (4) Prepare the coating: Coat the substrate coating prepared in (2) on the surface of the substrate material pretreated in step (1), then spray the cross-linking agent prepared in step (3) to form a sodium alginate hydrogel on the surface of the substrate material, then immerse it in the calcium chloride solution and wash it clean, and finally dry it to obtain a heat dissipation enhanced thin film coating.
[0012] Preferably, the substrate material in step (1) is metal, plastic, glass, fiber cloth or wood.
[0013] Preferably, the cleaning process in step (1) is to rinse with water and ethanol. When the substrate is metal, it needs to be degreased by first cleaning with acetone, citric acid or sodium hydroxide, and then rinsed with water and ethanol.
[0014] Preferably, the carbon nanomaterials in step (2) are multi-walled carbon nanotubes, single-walled carbon nanotubes or graphene.
[0015] Preferably, when the carbon nanomaterials in step (2) are multi-walled carbon nanotubes, the aspect ratio is 100 - 400.
[0016] Preferably, the ultrasonic time after adding the carbon nanomaterials in step (2) is 10 - 40 min.
[0017] Preferably, in the step (2), after adding the polyvinyl alcohol particles, the solution temperature during stirring is 50-90° C. and the stirring time is 30-90 min.
[0018] Preferably, the degree of polymerization of the polyvinyl alcohol in step (2) is 1700-2600. It can be selected from one of type 1788, type 1799, type 2099, type 2399, type 2488, type 2699, or a mixture of two or more thereof.
[0019] Preferably, in step (2), after adding sodium alginate, the solution temperature during stirring is 50-90° C. and the stirring time is 1-4 h.
[0020] Preferably, in step (3), the stirring time is 10-20 min.
[0021] Preferably, in step (3), the mass concentration of calcium chloride is 10-50%.
[0022] Preferably, in step (4), the immersion time in the calcium chloride solution is 5-8 hours.
[0023] Preferably, in step (4), the drying temperature is 80-120° C. and the drying time is 8-12 hours.
[0024] The present invention has the following beneficial effects:
[0025] a. Liquid water obtained by moisture absorption is used to remove part of the heat when the device is heated. The whole process runs intermittently and spontaneously, without the need for external force to drive, thus saving energy.
[0026] b. Use sodium alginate to cross-link calcium chloride to reduce calcium chloride leakage and alleviate corrosion problems. At the same time, sufficient calcium chloride loading also makes it have a large moisture absorption capacity.
[0027] c. The high emissivity of carbon nanotubes is used to remove heat in time, and its high thermal conductivity is used to reduce heat accumulation on the interface, alleviating the additional thermal resistance introduced by the coating, so that the final equilibrium temperature is more than 7 degrees lower than that of the aluminum plate radiator.
[0028] d. The preparation process is simple, requires less equipment, and the reagents and products in the whole process are non-toxic and harmless, which is suitable for industrial production, and is conducive to improving the heat dissipation capacity of the radiator and dealing with the heating problem of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Figure 1 It is a schematic diagram of the working principle of the coating.
[0030] Figure 2 It is a temperature curve comparison diagram of the thin film coating plate of the present invention and the aluminum plate under the same environment. DETAILED DESCRIPTION
[0031] The present invention will be described below in conjunction with specific embodiments, but is not limited to the following examples.
[0032] In the following embodiments, the experimental methods are conventional methods unless otherwise specified; the reagents and materials can be obtained from commercial sources unless otherwise specified.
[0033] Example 1:
[0034] A coating for enhancing the heat dissipation ability of a device and a preparation method thereof, and the specific implementation steps are as follows:
[0035] (1) The aluminum sheet is successively cleaned with 1% wt citric acid, water and absolute ethanol, and the pretreated aluminum sheet is obtained after drying.
[0036] (2) 1 g of polyvinyl alcohol type 1788 is added to 50 ml of deionized water, and stirred at 50 °C for 60 min to obtain solution A.
[0037] (3) 1 g of sodium alginate is added to solution A, and stirred at 90 °C for 2 h to obtain solution B.
[0038] (4) 0.025 g of multi-walled carbon nanotubes with an aspect ratio of 100 is added to solution B, and ultrasonically dispersed for 10 min to obtain the carbon nanotube base liquid C.
[0039] (5) 30 g of anhydrous calcium chloride is added to 30 ml of deionized water, and stirred for 10 min to prepare a cross-linked calcium chloride solution.
[0040] (6) After the base liquid C in step (4) is coated on the surface of the aluminum sheet, the anhydrous calcium chloride solution in (5) is sprayed. After cross-linking, it is immersed in the calcium chloride solution for 8 h.
[0041] (7) The impregnated sample is washed clean with deionized water to remove the excess calcium chloride residue, and then placed in a drying oven and dried at 100 °C for 12 h to obtain a heat dissipation enhancement coating that self-adheres to the surface of the aluminum sheet.
[0042] Example 2:
[0043] A coating for enhancing the heat dissipation ability of a device and a preparation method thereof, and the specific implementation steps are as follows:
[0044] (1) The aluminum sheet is successively cleaned with 1% wt citric acid, water and absolute ethanol, and the pretreated aluminum sheet is obtained after drying.
[0045] (2) 4 g of polyvinyl alcohol type 2099 is added to 50 ml of deionized water, and stirred at 80 °C for 30 min to obtain solution A.
[0046] (3) Add 2 g of sodium alginate to Solution A and stir at 60 °C for 2 h to obtain Solution B.
[0047] (4) Add 0.05 g of multi-walled carbon nanotubes with an aspect ratio of 200 to Solution B and ultrasonically disperse for 10 min to obtain the carbon nanotube base liquid C.
[0048] (5) Add 30 g of anhydrous calcium chloride to 30 ml of deionized water and stir for 10 min to prepare a cross-linked calcium chloride solution.
[0049] (6) After applying the base liquid C from step (4) on the surface of the aluminum sheet, spray the anhydrous calcium chloride solution in (5). After cross-linking, immerse it in the calcium chloride solution for 8 h.
[0050] (7) Wash the immersed sample with deionized water to remove the excess calcium chloride residue, then put it in an oven and dry at 80 °C for 12 h to obtain a heat dissipation enhancement coating that self-adheres to the surface of the aluminum sheet.
[0051] Example 3:
[0052] A coating for enhancing the heat dissipation ability of a device and its preparation method. The specific implementation steps are as follows:
[0053] (1) Clean the aluminum sheet successively with 1% wt citric acid, water and absolute ethanol, and dry it to obtain a pretreated aluminum sheet.
[0054] (2) Add 1.5 g of polyvinyl alcohol type 2399 to 50 ml of deionized water and stir at 80 °C for 60 min to obtain Solution A.
[0055] (3) Add 1 g of sodium alginate to Solution A and stir at 80 °C for 4 h to obtain Solution B.
[0056] (4) Add 0.05 g of multi-walled carbon nanotubes with an aspect ratio of 400 to Solution B and ultrasonically disperse for 40 min to obtain the carbon nanotube base liquid C.
[0057] (5) Add 15 g of anhydrous calcium chloride to 30 ml of deionized water and stir for 10 min to prepare a cross-linked calcium chloride solution.
[0058] (6) After applying the base liquid C from step (4) on the surface of the aluminum sheet, spray the anhydrous calcium chloride solution in (5). After cross-linking, immerse it in the calcium chloride solution for 5 h.
[0059] (7) Wash the immersed sample with deionized water to remove the excess calcium chloride residue, then put it in an oven and dry at 90 °C for 12 h to obtain a heat dissipation enhancement coating that self-adheres to the surface of the aluminum sheet.
[0060] Example 4:
[0061] A coating for enhancing the heat dissipation ability of a device and a preparation method thereof, and the specific implementation steps are as follows:
[0062] (1) The aluminum sheet is sequentially cleaned with 1% wt citric acid, water and absolute ethanol, and the pretreated aluminum sheet is obtained after drying.
[0063] (2) 1.5 g of polyvinyl alcohol type 2699 is added to 50 ml of deionized water, and stirred at 90 °C for 60 min to obtain solution A.
[0064] (3) 0.5 g of sodium alginate is added to solution A, and stirred at 90 °C for 3 h to obtain solution B.
[0065] (4) 0.1 g of multi-walled carbon nanotubes with an aspect ratio of 200 is added to solution B, and ultrasonically dispersed for 10 min to obtain the carbon nanotube base liquid C.
[0066] (5) 20 g of anhydrous calcium chloride is added to 30 ml of deionized water, and stirred for 20 min to prepare a cross-linked calcium chloride solution.
[0067] (6) After the base liquid C in step (4) is coated on the surface of the aluminum sheet, the anhydrous calcium chloride solution in (5) is sprayed. After cross-linking, it is immersed in the calcium chloride solution for 8 h.
[0068] (7) The impregnated sample is washed clean with deionized water, and after removing the excess calcium chloride residue, it is placed in a drying oven and dried at 80 °C, 100 °C, and 120 °C for 4 h each to obtain a heat dissipation enhancement coating that self-adheres to the surface of the aluminum sheet.
[0069] Example 5:
[0070] A coating for enhancing the heat dissipation ability of a device and a preparation method thereof, and the specific implementation steps are as follows:
[0071] (1) The aluminum sheet is sequentially cleaned with 1% wt citric acid, water and absolute ethanol, and the pretreated aluminum sheet is obtained after drying.
[0072] (2) 1.5 g of polyvinyl alcohol type 2488 is added to 50 ml of deionized water, and stirred at 80 °C for 60 min to obtain solution A.
[0073] (3) 1 g of sodium alginate is added to solution A, and stirred at 80 °C for 3 h to obtain solution B.
[0074] (4) 0.05 g of multi-walled carbon nanotubes with an aspect ratio of 400 is added to solution B, and ultrasonically dispersed for 10 min to obtain the carbon nanotube base liquid C.
[0075] (5) 15 g of anhydrous calcium chloride is added to 30 ml of deionized water, and stirred for 10 min to prepare a cross-linked calcium chloride solution.
[0076] (6) After applying the base liquid C in step (4) on the surface of the aluminum sheet, spray the anhydrous calcium chloride solution in (5). After cross-linking, immerse it in the calcium chloride solution for 5 h.
[0077] (7) Wash the impregnated sample with deionized water until clean. After removing the excess calcium chloride residue, put it into an oven and dry it at 90 °C for 12 h to obtain a heat dissipation strengthening coating that self-adheres to the surface of the aluminum sheet.
[0078] Example 6:
[0079] A coating for enhancing the heat dissipation ability of a device and a preparation method thereof. The specific implementation steps are as follows:
[0080] (1) Wash the aluminum sheet successively with 1% wt citric acid, water and absolute ethanol, and dry it to obtain a pretreated aluminum sheet.
[0081] (2) Add 2 g of polyvinyl alcohol type 1788 to 50 ml of deionized water and stir at 80 °C for 60 min to obtain solution A.
[0082] (3) Add 2 g of sodium alginate to solution A and stir at 50 °C for 4 h to obtain solution B.
[0083] (4) Add 0.1 g of multi-walled carbon nanotubes with an aspect ratio of 200 to solution B and ultrasonically disperse for 10 min to obtain carbon nanotube base liquid C.
[0084] (5) Add 3 g of anhydrous calcium chloride to 30 ml of deionized water and stir for 20 min to prepare a cross-linking calcium chloride solution.
[0085] (6) After applying the base liquid C in step (4) on the surface of the aluminum sheet, spray the anhydrous calcium chloride solution in (5). After cross-linking, immerse it in the calcium chloride solution for 5 h.
[0086] (7) Wash the impregnated sample with deionized water until clean. After removing the excess calcium chloride residue, put it into an oven and dry it at 80 °C, 100 °C, and 120 °C for 4 h each to obtain a heat dissipation strengthening coating that self-adheres to the surface of the aluminum sheet.
[0087] Example 7:
[0088] A coating for enhancing the heat dissipation ability of a device and a preparation method thereof. The specific implementation steps are as follows:
[0089] (1) Wash the aluminum sheet successively with 1% wt citric acid, water and absolute ethanol, and dry it to obtain a pretreated aluminum sheet.
[0090] (2) Add 1 g of polyvinyl alcohol type 2399 to 50 ml of deionized water and stir at 80 °C for 60 min to obtain solution A.
[0091] (3) Add 0.5 g of sodium alginate to Solution A and stir at 90 °C for 1 h to obtain Solution B.
[0092] (4) Add 0.1 g of multi-walled carbon nanotubes with an aspect ratio of 200 to Solution B and ultrasonically disperse for 10 min to obtain the carbon nanotube base liquid C.
[0093] (5) Add 30 g of anhydrous calcium chloride to 30 ml of deionized water and stir for 10 min to prepare a cross-linking calcium chloride solution.
[0094] (6) After applying the base liquid C from step (4) on the surface of the aluminum sheet, spray the anhydrous calcium chloride solution from (5). After cross-linking, immerse it in the calcium chloride solution for 5 h.
[0095] (7) Wash the impregnated sample with deionized water to remove the excess calcium chloride residue, and then put it into a drying oven. Dry it at 80 °C, 100 °C, and 120 °C for 4 h each to obtain a heat dissipation-enhancing coating that self-adheres to the surface of the aluminum sheet.
Claims
1. A method for preparing a thin film coating for enhancing the heat dissipation ability of a device, characterized in that, The details are as follows (1) Pretreat the substrate: Clean and dry the substrate material to obtain the pretreated substrate material; (2) Prepare the substrate coating: Add polyvinyl alcohol particles to water, stir to obtain solution A, then add sodium alginate to solution A, stir to obtain solution B, add carbon nanomaterials to solution B, and ultrasonically obtain a uniformly dispersed suspension C of carbon nanomaterials as the substrate coating; The mass ratio of carbon nanomaterials, polyvinyl alcohol, sodium alginate, and water is (0.05 - 0.2):(2 - 8):(1 - 4):100; (3) Prepare the crosslinking material: Add anhydrous calcium chloride to water, stir to obtain a calcium chloride solution as the crosslinking agent; (4) Prepare the coating: Coat the substrate coating prepared in (2) on the surface of the substrate material pretreated in step (1), then spray the crosslinking agent prepared in step (3) to form sodium alginate hydrogel on the surface of the substrate material, then immerse it in the calcium chloride solution and wash it clean, and finally dry it to obtain a heat dissipation enhanced thin film coating.
2. The preparation method of a thin film coating for enhancing the heat dissipation ability of a device according to claim 1, characterized in that, The substrate material in step (1) is metal, plastic, glass, fiber cloth or wood; The cleaning process is to rinse with water and ethanol. When the substrate is metal, it needs to be degreased with acetone, citric acid or sodium hydroxide first, and then rinsed with water and ethanol.
3. The preparation method of a thin film coating for enhancing the heat dissipation ability of a device according to claim 1, characterized in that The carbon nanomaterials in step (2) are multi-walled carbon nanotubes, single-walled carbon nanotubes or graphene.
4. The preparation method of a thin film coating for enhancing the heat dissipation ability of a device according to claim 3, characterized in that, When the carbon nanomaterials in step (2) are multi-walled carbon nanotubes, the aspect ratio is 100 - 400.
5. The preparation method of a thin film coating for enhancing the heat dissipation ability of a device according to claim 1, characterized in that, The ultrasonic time after adding the carbon nanomaterials in step (2) is 10 - 40 min; After adding the polyvinyl alcohol particles, the solution temperature during stirring is 50 - 90 °C, and the stirring time is 30 - 90 min; After adding sodium alginate, the solution temperature during stirring is 50 - 90 °C, and the stirring time is 1 - 4 h.
6. The preparation method of a thin film coating for enhancing the heat dissipation ability of a device according to claim 1, characterized in that, The degree of polymerization of the polyvinyl alcohol in step (2) is 1700 - 2600.
7. The preparation method of a thin film coating for enhancing the heat dissipation ability of a device according to claim 6, characterized in that, The degree of polymerization of polyvinyl alcohol is one or more mixtures of type 1788, type 1799, type 2099, type 2399, type 2488, type 2699.
8. The preparation method of a thin film coating for enhancing the heat dissipation ability of a device according to claim 1, characterized in that, In step (3), the stirring time is 10 - 20 min; The mass concentration of calcium chloride is 10 - 50%.
9. The preparation method of a thin film coating for enhancing the heat dissipation ability of a device according to claim 1, characterized in that, In step (4), the impregnation time in the calcium chloride solution is 5 - 8 h.
10. The preparation method of a thin film coating for enhancing the heat dissipation ability of a device according to claim 1, characterized in that, In step (4), the drying temperature is 80 - 120 °C, and the drying time is 8 - 12 h.