A reinforced heat spreading carbon-based composite film and a method of making the same

Abstract

The application discloses a reinforced heat-diffusing carbon-based composite film and a manufacturing method thereof, and specifically comprises the following steps: preparing a boron nitride precursor solution; fixing a graphite film on a flat plate; and coating the precursor solution on the graphite film. The carbon-based composite film prepared by the application can be applied to heat dissipation of systems and devices, and is especially suitable for heat dissipation technology of a spacecraft and heat dissipation of outdoor electronic devices. In the application, the boron nitride precursor solution is relatively easy to combine with the graphite film, and the performance of the boron nitride precursor solution and the graphite film is not affected.

Description

TECHNICAL FIELD

[0001] The present application relates to a reinforced heat spreading carbon-based composite film and a manufacturing method thereof, and belongs to the technical field of functional materials. BACKGROUND

[0002] With the development of society, people's work more and more rely on electronic equipment. There are many outdoor electronic equipment, they are affected by the sun's heat radiation and the heat of the device itself, and the temperature of the electronic equipment is increased, and the temperature is too high to cause the failure of the electronic equipment, so it is important to eliminate the influence of the two heat sources on the normal work of the electronic equipment. The existing cooling methods include air conditioning, forced ventilation and air heat exchange. However, the economy and reliability of the above methods need to be improved. Radiation cooling as a new cooling method solves the above problems. The boron nitride coating (coating A) has good radiation cooling performance, and the coating A can be covered on the surface of the electronic equipment, and the passive cooling of the coating A can reduce the influence of the sun's heat radiation, and then realize the cooling of the electronic equipment. However, the surface thermal conductivity of the coating A is poor, and the heat source on the electronic device is usually a point heat source, so in order to make the heat source dissipate as soon as possible, the point heat source should be quickly spread to the whole plane. SUMMARY

[0003] The purpose of the present application is to provide a reinforced heat spreading carbon-based composite film and a manufacturing method thereof, which has excellent heat dissipation performance.

[0004] The technical scheme for achieving the purpose of the present application is: a reinforced heat spreading carbon-based composite film and a manufacturing method thereof, the specific steps are:

[0005] S1, preparing a boron nitride precursor solution;

[0006] S2, fixing a graphite film on a flat plate;

[0007] S3, coating the boron nitride precursor solution on the graphite film.

[0008] Further, in S1, the boron nitride precursor solution is prepared by using boron nitride as raw material and potassium silicate as binder, and the mass ratio is 1:2.

[0009] Further, in S2, the graphite film with a thickness not less than 15 μm is fixed on the flat plate.

[0010] Further, in S3, the boron nitride precursor solution is coated on the graphite film by an adjustable doctor blade.

[0011] Further, in S3, the coating thickness is 280 μm~350 μm.

[0012] The application also provides the use of the reinforced heat spreading and radiating carbon-based composite film as a heat spreading and radiating layer.

[0013] Compared with the prior art, the application has the following beneficial effects:

[0014] 1. The carbon-based composite film prepared by the application can be applied to heat dissipation of systems and devices, and is particularly suitable for heat dissipation technology of spacecraft and heat dissipation of outdoor electronic devices.

[0015] 2. Compared with the existing coating A, the heat dissipation performance of the application is better.

[0016] 3. The required medicine of the application is easy to obtain, the manufacturing process is simple, the manufacturing time is relatively short, large-scale production can be realized, and the application has great practical application value.

[0017] 4. In the application, the boron nitride precursor solution and the graphite film are relatively easy to combine, and the performance of each is not affected. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a flow chart of the preparation method of the reinforced heat spreading and radiating carbon-based composite film of the application.

[0019] Figure 2 is a picture of coating A involved in the prior art after scanning electron microscope observation.

[0020] Figure 3 is a temperature distribution image of coating A involved in the prior art and the carbon-based composite film described in Example 1 of the application, Figure 3a is a line temperature distribution image of the over-center of the initial state of coating A, Figure 3b is a line temperature distribution image of the stable state of coating A, Figure 3c is a line temperature distribution image of the initial state of the carbon-based composite film, Figure 3d is a line temperature distribution image of the stable state of the carbon-based composite film.

[0021] Figure 4a is a reflectivity image of the carbon-based composite film prepared in Example 1-2 of the application in the solar waveband (0.3-2.5 μm), Figure 4b is a reflectivity image of the carbon-based composite film prepared in Example 1 of the application in the long-wavelength infrared waveband (2.5-25 μm).

[0022] Figure 5 is a physical picture of the radiation cooler made in Example 1 of the application.

[0023] Figure 6 is a distribution diagram of the thermocouple in the radiation cooler.

[0024] Figure 7aTemperature variation of the surface of the carbon-based composite film prepared in Example 1 and its heat source during the day (10:30-16:00), Figure 7b Temperature variation of the surface of the carbon-based composite film prepared in Example 1 and its heat source during the night (0:00-6:00). DETAILED DESCRIPTION

[0025] The application will be further described below with reference to the drawings.

[0026] The boron nitride (drug B) was used as the raw material, and the potassium silicate solution was used as the solvent. Then, the drug B and the potassium silicate solution were configured into a solution at a mass ratio of 1:2. The specific method was as follows: a certain amount of drug B was poured into the previously prepared potassium silicate solution, and the DF-101S heat collecting constant temperature heating magnetic stirrer was used to stir under the condition that the water bath temperature was 40°C until the particles of drug B were completely dissolved. The graphite film with a thickness of 25 um (Shenzhen Lexs Electronic Products Co., Ltd.) was fixed on a flat plate by using adhesive tape, and then the obtained solution was coated on the fixed graphite film by using an adjustable doctor blade. After the water was completely evaporated, the carbon-based composite film with different thicknesses was obtained. The preparation process is shown in Figure 1 .

[0027] Example 1

[0028] 1. The mass ratio of the two was required to be drug B: potassium silicate solution = 1:2. Therefore, 5 grams of drug B and 10 grams of potassium silicate solution were weighed respectively.

[0029] 2. The weighed particles of drug B were poured into the beaker containing the potassium silicate solution, the water bath temperature of the heat collecting constant temperature heating magnetic stirrer was set to 40°C, and the stirring was performed for 20 minutes until the particles were completely dissolved to obtain the precursor solution.

[0030] 3. The graphite film with a thickness of 25 um was fixed on a flat plate by using adhesive tape, which was to prevent the graphite film from being lifted up during the evaporation of the solution, thereby causing wrinkles. An adjustable doctor blade was used for coating, and the height of the adjustable doctor blade was controlled to be 1500 um. Then, it was naturally air-dried, and after the deionized water was evaporated, the carbon-based composite film with a thickness of 280 um was obtained.

[0031] Example 2

[0032] 1. The mass ratio of the two was required to be drug B: potassium silicate solution = 1:2. Therefore, 5 grams of drug B and 10 grams of potassium silicate solution were weighed respectively.

[0033] 2. The weighed particles of drug B were poured into the beaker containing the potassium silicate solution, the water bath temperature of the heat collecting constant temperature heating magnetic stirrer was set to 40°C, and the stirring was performed for 20 minutes until the particles were completely dissolved to obtain the precursor solution.

[0034] 3. The 25um thick graphite film was fixed on a flat plate with adhesive tape to prevent the graphite film from being carried up and causing wrinkles when the solution evaporates. The adjustable doctor blade was used for coating, and the height of the adjustable doctor blade was controlled at 2000um. Then it was naturally air-dried, and after the deionized water evaporated, a 350um thick carbon-based composite film was obtained.

[0035] Figure 2 The SEM image of coating A is given, and it can be found that the surface is composed of sheet structures of different sizes, which can effectively scatter sunlight and enhance radiation.

[0036] Figures 3a to 3d The line temperature distribution image of coating A and the carbon-based composite film prepared in Example 1 is given, and the temperature of the point heat source is 50℃. A copper column with a diameter of 5cm is connected with an external power source as a point heat source, and coating A and the carbon-based composite film are cut into a circle with a diameter of 34cm. The point heat source is placed at the center of the circle, and the temperature distribution of the surface of coating A and the carbon-based composite film is observed by an infrared thermal imager. As can be seen from Figure 3, after a long enough time, the temperature of the periphery of coating A is still low, while the overall surface temperature distribution of the carbon-based composite film is uniform. Therefore, the surface thermal conductivity of coating A is extremely poor, while the surface thermal conductivity of the carbon-based composite film in the present application is better, which can disperse the point heat source to the whole plane faster, and then dissipate heat. Therefore, the carbon-based composite film further improves the surface thermal conductivity of coating A.

[0037] Figure 4a The reflectivity image of the carbon-based composite film prepared in Examples 1-2 in the solar wave band (0.3-2.5um) is given, and it can be found that in the solar wave band (0.3-2.5um), the thicker the carbon-based composite film, the higher the corresponding reflectivity; Figure 4b The reflectivity image of the carbon-based composite film prepared in Example 1 in the long infrared wave band (2.5-25um) is given, and it can be found that in the "atmospheric window" wave band (8-13um), the carbon-based composite film has a low reflectivity, and because the transmittance of the composite film is extremely low, the carbon-based composite film has a high emissivity in the "atmospheric window" wave band. The above properties ensure that the carbon-based composite film has good radiation cooling performance.

[0038] In order to study the cooling performance of the carbon-based composite film, a simple radiation cooler was made. Figure 5 is the physical diagram of the radiation cooler.

[0039] Figure 6 is the specific distribution of the thermocouple. Figure 6In the device, 1 is a foam base, 2 is a tin foil, 3 is a polyimide heating film, 4 is a carbon-based composite film coating with an area of 82 mm x 45 mm and a thickness of 280 μm. The first thermocouple 5 is used to measure the temperature of the heat source without carbon-based composite film covering, the second thermocouple 6 is used to measure the temperature of the heat source covered by carbon-based composite film, i.e. the temperature of the lower surface of the carbon-based composite film, and the third thermocouple 7 is used to measure the temperature of the upper surface of the carbon-based composite film (in contact with the external environment). In the device, the contact between the thermocouples and the film is bonded with high-temperature resistant glue to reduce the influence of air convection on temperature measurement. K-type thermocouples are used in the experiment, the foam base has a heat-insulating effect, the tin foil is used to focus sunlight on the surface of the measured film and reduce air convection, the polyimide heating film is connected with an external power source as a heat source, and the external power source is adjusted to 2 W in the experiment to control the surface temperature of the heating film to be 50℃. On a sunny day, the radiation cooler is placed on the roof (east longitude 118°51′14″, north latitude 32°1′37″), and the temperature changes of the corresponding surfaces are observed by thermocouples.

[0040] Figure 7a The temperature changes of the surface of the carbon-based composite film with a thickness of 280 μm and a size of 82 mm x 45 mm and the heat source below the film were measured by the above-mentioned radiation cooler from 10:30 to 16:00. It was measured by an irradiance meter that the intensity of sunlight in the time period from 13:00 to 13:30 was 650 W / m 2 , and at this time the temperature of the heat source decreased by about 10℃, which shows that the carbon-based composite film has good heat dissipation performance. Figure 7b The temperature changes of the surface of the carbon-based composite film and the heat source below the film at night were shown in FIG. 4. It can be found that the carbon-based composite film also makes the temperature of the heat source decrease by about 2℃ at night, which shows that the carbon-based composite film also has certain heat dissipation performance at night.

Claims

1. A method for producing a reinforced heat spreading carbon-based composite film, characterized by, The specific steps are: S1, preparing a boron nitride precursor solution; S2, fixing a graphite film on a flat plate; S3, coating the boron nitride precursor solution on the graphite film; In S1, the boron nitride precursor solution is prepared by mixing boron nitride and potassium silicate at a mass ratio of 1:

2.

2. The method of claim 1, wherein, In S2, the graphite film with a thickness of not less than 15 μm is fixed on the flat plate.

3. The method of claim 1, wherein, In S3, the boron nitride precursor solution is coated on the graphite film by an adjustable doctor blade.

4. The method of claim 1, wherein, In S3, the coating thickness is 280 μm-350 μm.

5. The reinforced heat spreading and radiating carbon-based composite film prepared by the method according to any one of claims 1-4.

6. The use of the reinforced heat spreading and radiating carbon-based composite film prepared by the method according to any one of claims 1-4 as a heat spreading and radiating layer.

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