Expanded graphite paraffin phase change composite material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of thermal management materials, and particularly relates to an expanded graphite paraffin phase change composite material and a preparation method thereof. The expanded graphite paraffin phase change composite material provided by the invention is prepared from 8 to 10 percent of first-grade expandable graphite, 0.5 to 1.5 percent of second-grade expandable graphite and 88.5 to 91.5 percent of paraffin. Through the design of a two-stage grading expandable graphite coupling configuration, the expanded graphite paraffin phase change composite material with relatively good comprehensive thermal management performance is obtained. The expanded graphite paraffin phase change composite material provided by the invention has the advantages of high heat-conducting property and high phase change enthalpy value, and is particularly suitable for thermal management of electronic components in aerospace equipment. Meanwhile, raw materials are low in price and easy to obtain, and the method is more suitable for industrial application.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal management materials, and in particular relates to an expanded graphite paraffin phase change composite material and a preparation method and application thereof. Background Art

[0002] When spacecraft operate at high speeds, external heat fluxes fluctuate significantly, causing dramatic changes in the thermal load on instruments and equipment. In particular, certain specialized equipment with low heat capacity has a narrow operating temperature range and high requirements for temperature fluctuation, which presents numerous technical challenges for spacecraft thermal control design. Phase change materials offer the advantages of isothermal or near-isothermal phase change, absorbing and releasing large amounts of latent heat, making them particularly suitable for instruments and equipment with periodic pulsed operation. However, currently used phase change materials generally suffer from low thermal conductivity, making it difficult to meet the growing heat transfer requirements of electronic devices. Therefore, improving the thermal conductivity of materials without excessive latent heat loss is key to improving traditional phase change materials.

[0003] Paraffin wax-based materials are commonly used organic phase change materials in thermal management due to their excellent heat storage capacity (160-270 J / g), consistent melting, chemical inertness, self-nucleation, and lack of phase separation. However, their low thermal conductivity, large melt volume change, and potential leakage are also drawbacks that cannot be ignored. To further optimize the thermal performance of paraffin-based phase change materials, expanded graphite with higher thermal conductivity can be added to improve the low thermal conductivity of paraffin wax. The good adsorption properties of its porous skeleton can also be used to address the paraffin's proneness to leakage. However, the contradiction between the thermal conductivity and heat storage capacity of expanded graphite and paraffin phase change composites is significant: as the thermal conductivity of the composite increases, the heat storage capacity decreases. Because the thermal conductivity and heat storage capacity of composite materials are inversely related, this contradiction cannot be completely resolved.

[0004] At present, although the heat storage capacity of the expanded graphite paraffin composite materials currently in service is relatively high, their thermal conductivity and overall thermal management performance are still poor. Summary of the Invention

[0005] The object of the present invention is to provide an expanded graphite paraffin wax phase change composite material and a preparation method thereof. The expanded graphite paraffin wax phase change composite material provided by the present invention has a greatly improved thermal conductivity while ensuring that the composite material has excellent heat storage capacity, thereby having good comprehensive thermal management performance.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides an expanded graphite paraffin phase change composite material, comprising the following components in percentage by mass:

[0008] The first-grade expandable graphite contains 8-10%, the second-grade expandable graphite contains 0.5-1.5%, and the paraffin contains 88.5-91.5%; the mesh number of the second-grade expandable graphite is greater than the mesh number of the first-grade expandable graphite, and the difference between the mesh number of the second-grade expandable graphite and the mesh number of the first-grade expandable graphite is 50-150 meshes.

[0009] Preferably, the mesh size of the first graded expandable graphite is 50 meshes.

[0010] Preferably, the mesh size of the second graded expandable graphite is 100-200 meshes.

[0011] Preferably, the composition comprises the following components in percentage by weight: 9% of the first-grade expandable graphite, 1% of the second-grade expandable graphite, and 90% of paraffin wax;

[0012] The present invention provides a method for preparing the expanded graphite paraffin wax phase change composite material described in the above technical solution, comprising the following steps:

[0013] Mixing the first graded expandable graphite and the second graded expandable graphite to obtain a graphite mixture;

[0014] heating the graphite mixture to expand it, thereby obtaining an expanded graphite mixture;

[0015] placing the expanded graphite mixture in a mold and compressing it, wherein the compression is performed in a height direction to obtain an expanded graphite continuous skeleton, wherein the height of the expanded graphite continuous skeleton is 85-95% of the original height before compression;

[0016] Paraffin is spread on the upper surface of the expanded graphite continuous skeleton, and then heated under vacuum conditions. The paraffin melt obtained by melting the paraffin soaks the expanded graphite continuous skeleton, and the expanded graphite paraffin phase change composite material is obtained after cooling.

[0017] Preferably, the expansion temperature is 895-905°C and the time is 28-32s;

[0018] After obtaining the graphite mixture and before the expansion, the graphite mixture is pre-dried. The pre-drying is performed under vacuum conditions at a temperature of 55 to 65° C. for 10 to 12 hours.

[0019] Preferably, the height of the expanded graphite continuous skeleton is 88-92% of the original height before compression.

[0020] Preferably, the vacuum degree of the vacuum condition is ≤200 Pa; and the heating temperature is 20 to 40° C. above the melting point of paraffin.

[0021] Preferably, the initial composite material is directly obtained after the paraffin wax melt immerses the expanded graphite continuous skeleton, and before cooling, the process further comprises: keeping the initial composite material warm under normal pressure for 1 to 2 hours; the keeping temperature is 20 to 40° C. above the melting point of the paraffin wax.

[0022] The present invention provides the use of the expanded graphite wax phase change composite material described in the above technical solution or the expanded graphite wax phase change composite material prepared by the preparation method described in the above technical solution in thermal management of electronic components in aerospace equipment.

[0023] The present invention provides an expanded graphite paraffin phase change composite material, comprising the following components in percentage by weight: 8-10% first-grade expandable graphite, 0.5-1.5% second-grade expandable graphite, and 88.5-91.5% paraffin; the mesh size of the second-grade expandable graphite is greater than the mesh size of the first-grade expandable graphite, and the difference between the mesh sizes of the second-grade expandable graphite and the first-grade expandable graphite is 50-150 meshes. The present invention has found that, compared with a phase change composite material obtained by compounding expandable graphite and paraffin with a single mesh size, the present invention, through the design of a two-grade expandable graphite (EG) coupling configuration, obtains an expanded graphite continuous skeleton with a continuous network structure, which is compounded with paraffin to obtain an expanded graphite paraffin phase change composite material with better comprehensive thermal management performance. Under the premise that the mass content of graphite reinforcement in the phase change composite material is similar, the heat storage capacity of the phase change composite material provided by the present invention is close to that of a single-mesh expanded graphite paraffin phase change composite material, but the thermal conductivity is greatly improved. Furthermore, compared to expanded graphite carbon nanotube paraffin composites, this invention utilizes low-cost expandable graphite as the composite's reinforcement. Through a two-stage, graded expandable graphite coupling design, this yields an expanded graphite paraffin phase change composite with superior overall thermal management performance. The raw materials are inexpensive and readily available, making them more suitable for industrial applications.

[0024] The present invention provides a method for preparing the expanded graphite paraffin wax phase change composite material described in the above technical solution, comprising the following steps: mixing the first-graded expandable graphite and the second-graded expandable graphite to obtain a graphite mixture; heating the graphite mixture to expand it to obtain an expanded graphite mixture; placing the expanded graphite mixture in a mold and compressing it along its height to obtain an expanded graphite continuous skeleton, wherein the height of the expanded graphite continuous skeleton is 85-95% of its original height before compression; laying paraffin wax on the upper surface of the expanded graphite continuous skeleton, then heating under vacuum conditions to melt the paraffin wax to obtain a paraffin melt that immerses the expanded graphite continuous skeleton, and cooling to obtain the expanded graphite paraffin wax phase change composite material. The present invention first obtains an expanded graphite continuous skeleton by compression, and then uses a melt infiltration method to prepare the phase change composite material, thereby obtaining an expanded graphite paraffin wax phase change composite material with excellent comprehensive thermal management performance. The preparation method is simple and easy to implement, making it more suitable for industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the process of "prefabricated skeleton → melt infiltration" method provided by the present invention and photos of the material transformation process. DETAILED DESCRIPTION

[0026] The present invention provides an expanded graphite paraffin phase change composite material, comprising the following components in percentage by mass:

[0027] The first-grade expandable graphite contains 8-10%, the second-grade expandable graphite contains 0.5-1.5%, and the paraffin contains 88.5-91.5%; the mesh number of the second-grade expandable graphite is greater than the mesh number of the first-grade expandable graphite, and the difference between the mesh number of the second-grade expandable graphite and the mesh number of the first-grade expandable graphite is 50-150 meshes.

[0028] In the present invention, unless otherwise specified, all preparation raw materials / components are commercially available products well known to those skilled in the art.

[0029] The expanded graphite wax phase change composite material provided by the present invention comprises 8-10% by mass, preferably 9% of the first grade expandable graphite. In the present invention, the mesh size of the first grade expandable graphite is preferably 50 meshes.

[0030] The expanded graphite paraffin phase change composite material provided by the present invention comprises 0.5-1.5% by mass of the second graded expandable graphite, preferably 1%. In the present invention, the mesh size of the second graded expandable graphite is 100-200 mesh, more preferably 100 mesh, 150 mesh or 200 mesh.

[0031] The difference between the mesh number of the second-graded expandable graphite and the mesh number of the first-graded expandable graphite is 50 meshes, 100 meshes or 150 meshes.

[0032] Calculated by mass percentage, the expanded graphite paraffin wax phase change composite material provided by the present invention comprises 88.5-91.5% paraffin wax (PW), preferably 90%.

[0033] In the present invention, the melting temperature range of the paraffin wax is preferably 68-78°C.

[0034] The expanded graphite paraffin wax phase change composite material provided by the present invention has the advantages of high thermal conductivity and high phase change enthalpy value, and is particularly suitable for thermal management of electronic components in aerospace equipment.

[0035] The present invention provides a method for preparing the expanded graphite paraffin wax phase change composite material described in the above technical solution, comprising the following steps:

[0036] Mixing the first graded expandable graphite and the second graded expandable graphite to obtain a graphite mixture;

[0037] heating the graphite mixture to expand it, thereby obtaining an expanded graphite mixture;

[0038] placing the expanded graphite mixture in a mold and compressing it, wherein the compression is performed in a height direction to obtain an expanded graphite continuous skeleton, wherein the height of the expanded graphite continuous skeleton is 85-95% of the original height before compression;

[0039] Paraffin is spread on the upper surface of the expanded graphite continuous skeleton, and then heated under vacuum conditions. The paraffin melt obtained by melting the paraffin soaks the expanded graphite continuous skeleton, and the expanded graphite paraffin phase change composite material is obtained after cooling.

[0040] The present invention mixes the first-grade expandable graphite and the second-grade expandable graphite to obtain a graphite mixture. The present invention has no special requirements on the specific implementation of the mixing.

[0041] After obtaining the graphite mixture, the present invention heats the graphite mixture and expands it to obtain an expanded graphite mixture. In the present invention, after obtaining the graphite mixture, the present invention preferably further comprises pre-drying the graphite mixture before the expansion to obtain a dried graphite mixture, and then expanding the dried graphite mixture. The pre-drying is preferably carried out under vacuum conditions. The pre-drying temperature is preferably 55 to 65°C. The pre-drying time is preferably 10 to 12 hours. The pre-drying is carried out in a vacuum drying oven. In the present invention, the expansion is carried out in a muffle furnace. The expansion temperature is preferably 895 to 905°C. The expansion time is preferably 28 to 32 seconds. By controlling the temperature and time of the expansion, the present invention can fully expand the volume of the two graded expandable graphites, which is conducive to the subsequent acquisition of a continuous skeleton of expanded graphite.

[0042] After obtaining the expanded graphite mixture, the present invention places the expanded graphite mixture in a mold and compresses it. The compression is performed along the height direction to obtain an expanded graphite continuous skeleton, wherein the height of the expanded graphite continuous skeleton is 85-95% of the original height before compression. In the present invention, the compression is preferably performed as a tablet, and the compression is preferably performed at room temperature. The present invention may also be referred to as cold pressing. The mold is preferably a tableting mold. The height of the expanded graphite continuous skeleton is preferably 88-92% of the original height before compression. By controlling the compression ratio, the present invention ensures that both an expanded graphite continuous skeleton and a pore structure with uniform size and distribution are obtained. In the present invention, the average pore size of the expanded graphite continuous skeleton is approximately 10-13 nm.

[0043] After obtaining the expanded graphite continuous skeleton, the present invention covers the upper surface of the expanded graphite continuous skeleton with paraffin wax, and then heats it under vacuum conditions. The paraffin melt obtained by melting the paraffin wax immerses the expanded graphite continuous skeleton, and the expanded graphite paraffin phase change composite material is obtained after cooling. In the present invention, the paraffin wax is covered on the upper surface of the expanded graphite in the form of solid paraffin wax. The present invention covers the paraffin wax on the upper surface of the expanded graphite continuous skeleton, places the two in a container, fixes the expanded graphite continuous skeleton to the bottom of the container, and then heats it under vacuum conditions. The heating is preferably carried out in a vacuum drying oven. The vacuum degree of the vacuum condition is preferably ≤200 Pa. The heating temperature is preferably 20 to 40°C above the melting point of the paraffin. By controlling the vacuum conditions and the heating temperature, the present invention can allow the paraffin melt to fully enter the pore structure of the expanded graphite continuous skeleton to obtain a phase change composite material with uniform composition.

[0044] In the present invention, the initial composite material is directly obtained after the paraffin wax solution is immersed in the expanded graphite continuous skeleton. Prior to the cooling, the present invention preferably further comprises: depressurizing the initial composite material from a vacuum condition to atmospheric pressure, and then maintaining it at atmospheric pressure for 1 to 2 hours. The temperature of the maintenance is preferably 20 to 40°C above the melting point of the paraffin wax. By maintaining the temperature at atmospheric pressure for 1 to 2 hours, the present invention utilizes atmospheric pressure to more evenly infiltrate the liquid paraffin into the pores of the expanded graphite continuous skeleton, thereby achieving a more uniform distribution of the expanded graphite continuous skeleton and the paraffin wax.

[0045] In the present invention, the cooling is preferably natural cooling.

[0046] The present invention provides the use of the expanded graphite wax phase change composite material described in the above technical solution or the expanded graphite wax phase change composite material prepared by the preparation method described in the above technical solution in thermal management of electronic components in aerospace equipment.

[0047] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0048] The following examples are based on Figure 1 The preparation process is shown in the following example. The simulated picture of the material during the preparation process is as follows: Figure 1 As shown in .

[0049] Example 1:

[0050] 9 grams of 50-mesh expandable graphite and 1 gram of 100-mesh expandable graphite were mixed to form a graphite mixture, which was then dried in a vacuum drying oven at 60±5°C for 12 hours. The mixture was then placed in a muffle furnace at 900±5°C for 30 seconds before expansion. The expanded graphite mixture was placed in a tableting mold and compressed vertically to 90% of its original loose height, producing a porous expanded graphite continuous skeleton. 90 grams of paraffin wax was weighed and placed in a container, with the expanded graphite continuous skeleton secured to the bottom. The container was then placed in a vacuum drying oven. After evacuating the container to below 200 Pa, the container was heated to 150°C. Once the solution formed by the complete melting of the paraffin wax submerged the expanded graphite continuous skeleton, the vacuum was removed. After maintaining the mixture in the drying oven at ambient pressure for 1.5 hours, the mixture was removed from the heat and allowed to cool naturally. After the paraffin wax completely solidified, the expanded graphite-paraffin phase change composite material was obtained. The phase change enthalpy and thermal conductivity of the expanded graphite-wax phase change composite material were measured and are listed in Table 1.

[0051] Example 2:

[0052] 9 grams of 50-mesh expandable graphite and 1 gram of 150-mesh expandable graphite were mixed to create a graphite mixture, which was then dried in a vacuum drying oven at 60±5°C for 10 hours. The mixture was then placed in a muffle furnace at 900±5°C for 30 seconds before expansion. The expanded graphite mixture was placed in a tableting mold and compressed vertically to 90% of its original loose height, producing a porous expanded graphite continuous skeleton. 90 grams of paraffin wax was weighed and placed in a container, with the expanded graphite continuous skeleton secured to the bottom. The container was then placed in a vacuum drying oven. After evacuating the container to below 200 Pa, the container was heated to 150°C. Once the solution formed by the complete melting of the paraffin wax submerged the expanded graphite continuous skeleton, the vacuum was removed. After maintaining the mixture in the drying oven at ambient pressure for 2 hours, the mixture was removed from the heat and allowed to cool naturally. Once the paraffin wax had completely solidified, the expanded graphite-paraffin phase change composite material was obtained. The phase change enthalpy and thermal conductivity of the expanded graphite-wax phase change composite material were measured and are listed in Table 1.

[0053] Example 3:

[0054] 9 grams of 50-mesh expandable graphite and 1 gram of 200-mesh expandable graphite were mixed to form a graphite mixture, which was then dried in a vacuum drying oven at 60±5°C for 11 hours. The mixture was then placed in a muffle furnace at 900±5°C for 30 seconds before expansion. The expanded graphite mixture was placed in a tableting mold and compressed vertically to 90% of its original loose height, producing a porous expanded graphite continuous skeleton. 90 grams of paraffin wax was weighed and placed in a container, with the expanded graphite continuous skeleton secured to the bottom. The container was then placed in a vacuum drying oven. After evacuating the container to below 200 Pa, the container was heated to 150°C. Once the solution formed by the complete melting of the paraffin wax submerged the expanded graphite continuous skeleton, the vacuum was removed. After maintaining the mixture in the drying oven at ambient pressure for 1 hour, heating was stopped and the mixture was allowed to cool naturally. After the paraffin wax completely solidified, the expanded graphite-paraffin phase change composite material was obtained. The phase change enthalpy and thermal conductivity of the expanded graphite-wax phase change composite material were measured and are listed in Table 1.

[0055] Comparative Example 1:

[0056] Weigh 10 grams of 50-mesh expandable graphite and dry it in a vacuum drying oven at 60±5°C for 12 hours. The expandable graphite was then placed in a muffle furnace at 900±5°C for 30 seconds before expansion. The expanded graphite was placed in a tableting mold and compressed to 90% of its original loose height, producing a porous, continuous expanded graphite skeleton. Weigh 90 grams of paraffin wax and cover the upper surface of the expanded graphite skeleton. Both were placed in a container, with the expanded graphite skeleton secured to the bottom, and placed in a vacuum drying oven. After evacuating the container to below 200 Pa, the container was heated to 150°C. Once the paraffin completely melted and the resulting solution submerged the graphite skeleton, the vacuum was removed. After maintaining the temperature in the drying oven at ambient pressure for 2 hours, heating was stopped and the product was allowed to cool naturally. After the paraffin wax completely solidified, an expanded graphite-wax-wax phase change composite was produced. The phase change enthalpy and thermal conductivity of the expanded graphite-wax-wax phase change composite were measured and are listed in Table 1.

[0057] Comparative Example 2:

[0058] Weigh 10 grams of 200-mesh expandable graphite and dry it in a vacuum drying oven at 60±5°C for 12 hours. The expandable graphite was then placed in a muffle furnace at 900±5°C for 30 seconds before being removed. The expanded graphite was placed in a tableting mold and compressed in height to 90% of its original loose height, producing a porous, continuous expanded graphite skeleton. Weigh 90 grams of paraffin wax and cover the upper surface of the expanded graphite skeleton. Both were placed in a container, with the expanded graphite skeleton secured to the bottom, and placed in a vacuum drying oven. After evacuating to below 200 Pa, the container was heated to 150°C. Once the paraffin completely melted and the resulting solution submerged the graphite skeleton, the vacuum was removed. After maintaining the temperature in the drying oven at ambient pressure for 2 hours, heating was stopped and the product was allowed to cool naturally. After the paraffin wax completely solidified, an expanded graphite-wax-wax phase change composite was produced. The phase change enthalpy and thermal conductivity of the expanded graphite-wax-wax phase change composite were measured and are listed in Table 1.

[0059] Comparative Example 3:

[0060] Weigh 90 grams of paraffin wax, place it in a container, and place it in a vacuum drying oven. After evacuating the container to below 200 Pa, heat it to 150°C. Once the wax is completely melted, remove the vacuum. After holding the container at atmospheric pressure for 2 hours, remove the heat and allow it to cool naturally. Once the wax has completely solidified, a paraffin block phase change material is obtained. The phase change enthalpy and thermal conductivity of the material were measured and are listed in Table 1.

[0061] Table 1 Phase change latent heat and thermal conductivity of phase change materials prepared in Examples and Comparative Examples

[0062]

[0063] Table 2 shows the material ratios of the above-mentioned embodiments and comparative examples. Table 3 shows the shape characteristics of the skeleton pores of the phase change materials prepared by the above-mentioned embodiments and comparative examples measured using the gas adsorption method (BET method). It can be seen that the addition of small-particle expanded graphite increases the specific surface area and volume of the expanded graphite skeleton pores. The increase in specific surface area provides more nucleation sites for the crystallization process of paraffin wax, which is conducive to the uniform distribution of paraffin wax in the skeleton and the regulation of crystallization behavior. During the pressing process, a large number of small closed pores are generated inside the skeleton. These pores not only reduce the effective pore volume of the skeleton, but also limit the permeability and storage capacity of paraffin wax. The introduction of small-particle expanded graphite can effectively reduce the number of small closed pores caused by excessive compression, thereby increasing the overall pore volume of the skeleton. The filling effect of small-particle graphite particles also increases the average pore size of the skeleton, making the pore structure more open and connected. This pore structure significantly improves the permeability of paraffin wax in the skeleton, allowing it to be more evenly distributed inside the skeleton, thereby enhancing the overall performance of the composite material. However, when the size difference between the two expanded graphites is too large, the construction and support effect of the small-particle expanded graphite on the skeleton pores begins to weaken.

[0064] Table 2 Material ratios of Examples and Comparative Examples

[0065] Material PW (wt%) EG-50 (wt.%) EG-100 (wt.%) EG-150 (wt.%) EG-200 (wt.%) Example 1 90 10 1 / / Example 2 90 9 / 1 / Example 3 90 9 / / 1 Comparative Example 1 90 10 / / / Comparative Example 2 90 / / / 10 Comparative Example 3 100 / / / /

[0066] Table 3 Shape characteristics of the skeleton pores of the composite materials prepared in Examples and Comparative Examples

[0067]

[0068] The above examples demonstrate that, under the same expanded graphite dosage and preparation process conditions, the highly conductive expanded graphite-wax phase change composite material of the present invention not only achieves a slight increase in phase change latent heat capacity but also a significant improvement in thermal conductivity, further exploring the material's thermal management potential. The composite material prepared by the present invention is a beneficial supplement to existing expanded graphite-wax phase change composite systems, supporting thermal management of aerospace electronic devices.

[0069] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. An expanded graphite paraffin wax phase change composite material, characterized in that: Includes the following components in percentage by mass: The first-grade expandable graphite contains 8-10%, the second-grade expandable graphite contains 0.5-1.5%, and the paraffin contains 88.5-91.5%; the mesh number of the second-grade expandable graphite is greater than the mesh number of the first-grade expandable graphite, and the difference between the mesh number of the second-grade expandable graphite and the mesh number of the first-grade expandable graphite is 50-150 meshes.

2. The expanded graphite paraffin wax phase change composite material according to claim 1, characterized in that The mesh number of the first-graded expandable graphite is 50 meshes.

3. The expanded graphite paraffin wax phase change composite material according to claim 1, characterized in that The mesh size of the second-graded expandable graphite is 100-200 meshes.

4. The expanded graphite paraffin wax phase change composite material according to any one of claims 1 to 3, characterized in that: The invention comprises the following components in percentage by mass: 9% of first-grade expandable graphite, 1% of second-grade expandable graphite, and 90% of paraffin wax.

5. The method for preparing the expanded graphite paraffin phase change composite material according to any one of claims 1 to 4, characterized in that: The following steps are involved: Mixing the first graded expandable graphite and the second graded expandable graphite to obtain a graphite mixture; heating the graphite mixture to expand it, thereby obtaining an expanded graphite mixture; placing the expanded graphite mixture in a mold and compressing it, wherein the compression is performed in a height direction to obtain an expanded graphite continuous skeleton, wherein the height of the expanded graphite continuous skeleton is 85-95% of the original height before compression; Paraffin is spread on the upper surface of the expanded graphite continuous skeleton, and then heated under vacuum conditions. The paraffin melt obtained by melting the paraffin soaks the expanded graphite continuous skeleton, and the expanded graphite paraffin phase change composite material is obtained after cooling.

6. The preparation method according to claim 5, characterized in that The expansion temperature is 895-905°C and the time is 28-32s; After obtaining the graphite mixture and before the expansion, the graphite mixture is pre-dried. The pre-drying is performed under vacuum conditions at a temperature of 55 to 65° C. for 10 to 12 hours.

7. The preparation method according to claim 5, characterized in that The height of the expanded graphite continuous skeleton is 88-92% of the original height before compression.

8. The preparation method according to claim 5, characterized in that The vacuum degree of the vacuum condition is ≤200 Pa; the heating temperature is 20 to 40° C. above the melting point of paraffin.

9. The preparation method according to claim 5, characterized in that The initial composite material is directly obtained after the paraffin wax melt immerses the expanded graphite continuous skeleton. Before cooling, the initial composite material is kept warm for 1 to 2 hours under normal pressure; the keeping temperature is 20 to 40° C. above the melting point of the paraffin wax.

10. Use of the expanded graphite wax phase change composite material according to any one of claims 1 to 4 or the expanded graphite wax phase change composite material prepared by the preparation method according to any one of claims 5 to 9 in thermal management of electronic components in aerospace equipment.

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