Vacuum packaging graphene titanium alloy composite heat diffusion plate structure and preparation method

Abstract

The invention relates to a vacuum packaging graphene titanium alloy composite heat diffusion plate structure and a preparation method. The vacuum packaging graphene titanium alloy composite heat diffusion plate structure comprises a graphene plate, a titanium alloy cover plate, a titanium alloy bottom plate and a middle layer. A square groove is formed in the center of the titanium alloy bottom plate, the graphene plate is arranged in the groove, and the thickness of the graphene plate is larger than the depth of the groove; the middle layer is arranged on the upper surface of the titanium alloy bottom plate; a gap is formed between the outer edge of the graphene plate and the inner wall of the groove, and the titanium alloy cover plate is coaxially arranged on the graphene plate; and the titanium alloy cover plate and the titanium alloy bottom plate are used for packaging the graphene plate in the groove by using a vacuum brazing method. According to the method, graphene vacuum packaging can be achieved, the problem of graphene oxidation in the using process is avoided, the graphene titanium alloy interface is tightly attached, the interface thermal resistance is reduced, and the heat transfer efficiency is improved.

Description

Technical Field

[0001] This application relates to the field of aviation manufacturing technology, and particularly to a vacuum-packaged graphene-titanium alloy composite heat spreader structure and a preparation method thereof. Background Art

[0002] Titanium alloys have excellent properties such as low density, high specific strength, and excellent corrosion resistance. The metal honeycomb sandwich structure made of titanium alloy materials is a structural form that combines good heat insulation and load-bearing performance, and has been widely used in TPS systems, such as the heat protection systems of the Orion return capsule, the X-33 hypersonic aircraft, and cruise aircraft engines. In order to ensure the comprehensive performance of load-bearing and heat insulation of the thermal protection structure, titanium alloy honeycomb sandwich structures are usually used in combination with heat insulation materials (heat insulation felts, heat insulation cotton, aerogels, etc.).

[0003] A large number of studies have shown that in composite thermal protection structures, the heat insulation performance of the main part can meet the usage requirements, but at positions such as connectors and brackets of the structure, due to the absence of a heat insulation layer, heat is conducted too quickly from the high-temperature area of the external surface along the connection structure to the low-temperature area inside. And the in-plane thermal conductivity of titanium alloy is relatively low (less than 20W·m -1 ·K -1 ), and the heat at the contact position between the cold-face titanium alloy panel and the connector cannot be diffused to other parts of the panel in time, causing the extreme temperature to appear prematurely or excessively at this position, resulting in the premature failure of the entire thermal protection system. Therefore, it is urgent to solve the problem of the relatively low in-plane thermal conductivity of titanium alloy materials. On the basis of the excellent properties of titanium alloy materials such as light weight, high strength, and high temperature resistance, further improve its thermophysical properties, realize the rapid and uniform cooling surface temperature, and improve the long-term use reliability of the thermal protection structure of hypersonic aircraft.

[0004] Graphene is a nanomaterial (GNPs) with a two-dimensional lattice structure composed of carbon atoms in a hexagonal shape, and the monolayer thickness is only 0.34nm; defect-free graphene has extremely strong mechanical properties and good functional properties, and the in-plane thermal conductivity can reach 1200-1500W·m -1 ·K -1 , and the density is relatively low, only 2.1-2.3g / cm 3 . Adding graphene materials to the titanium alloy matrix to make a graphene / titanium alloy composite heat spreader can improve the thermal conductivity of titanium alloy without increasing or even reducing the weight. The powder metallurgy method has mature technology, good process adjustability, rapid forming, and is easy to obtain a refined grain structure, and is the most commonly used preparation method for graphene-reinforced titanium matrix composites. However, for the composites prepared by the powder metallurgy method, graphene is often in a discontinuous state in the titanium alloy matrix, and there are a large number of interfaces between graphene / titanium alloy dissimilar materials in the heat transfer path, resulting in an unsatisfactory enhancement effect of the graphene / titanium alloy composite in terms of heat conduction.

[0005] To fully utilize the high thermal conductivity of graphene, it is necessary to ensure the structural integrity of graphene and form a continuous graphene network in the metal matrix. By using welding to composite graphene sheets / membranes with titanium alloy thin plates to prepare a graphene / titanium alloy composite heat spreader, the structural integrity of graphene can be ensured and a continuous graphene network can be formed in the metal matrix, significantly improving the in-plane thermal conductivity of titanium alloy materials. However, titanium is relatively reactive and prone to interfacial reactions with graphene during welding, in-situ generating a TiC reaction layer. TiC belongs to the ceramic phase, with high hardness, large brittleness, and low thermal conductivity, significantly increasing the interfacial brittleness and reducing the mechanical properties and thermal conductivity of the joint; graphene is prone to oxidation in high-temperature environments, resulting in a decrease in heat transfer performance. Summary of the Invention

[0006] To solve the above problems, the present application provides a vacuum-packaged graphene-titanium alloy composite heat spreader structure and a preparation method.

[0007] In a first aspect, the present application provides a vacuum-packaged graphene-titanium alloy composite heat spreader structure, including a graphene plate, a titanium alloy cover plate, a titanium alloy bottom plate, and an intermediate layer;

[0008] A square groove is provided at the center of the titanium alloy bottom plate, the graphene plate is disposed in the groove, and the thickness of the graphene plate is higher than the depth of the groove; the intermediate layer is disposed on the upper surface of the titanium alloy bottom plate;

[0009] There is a gap between the outer edge of the graphene plate and the inner wall of the groove, and the titanium alloy cover plate is coaxially disposed on the graphene plate; the titanium alloy cover plate and the titanium alloy bottom plate use vacuum brazing to encapsulate the graphene plate in the groove.

[0010] Further, the width of the inner edge of the groove from the outer edge of the titanium alloy bottom plate is not less than 10 mm.

[0011] Further, pure nickel coatings are prepared on the upper and lower surfaces of the graphene plate by magnetron sputtering.

[0012] Further, the thickness of the pure nickel coating is 5 - 10 μm.

[0013] Further, the intermediate layer is a foil-shaped titanium-based filler metal and is disposed on the upper surface of the titanium alloy bottom plate by resistance spot welding.

[0014] Further, the graphene plate is disposed at the center of the groove.

[0015] Further, the gap between the outer edge of the graphene plate and the inner wall of the groove is 2 - 3 mm.

[0016] Furthermore, the upper surface of the graphene plate is 0.1 - 0.2 mm higher than the upper surface of the titanium alloy bottom plate.

[0017] In a second aspect, the present application provides a method for preparing a vacuum - encapsulated graphene - titanium alloy composite heat - spreading plate structure for preparing the vacuum - encapsulated graphene - titanium alloy composite heat - spreading plate structure as described above;

[0018] The method for preparing the vacuum - encapsulated graphene - titanium alloy composite heat - spreading plate structure includes:

[0019] Use a machining method to prepare a square groove in the center of the titanium alloy bottom plate, and the groove is coaxially arranged with the titanium alloy bottom plate;

[0020] Place the graphene plate in the groove, the thickness of the graphene plate is higher than the depth of the groove, and place the intermediate layer on the upper surface of the titanium alloy bottom plate;

[0021] Coaxially arrange and press the titanium alloy cover plate on the graphene plate to obtain a pre - welded part of the titanium alloy cover plate / intermediate layer / graphene plate / titanium alloy bottom plate composite structure;

[0022] Put the assembled pre - welded part into a vacuum brazing furnace for vacuum brazing to obtain a vacuum - encapsulated graphene - titanium alloy composite heat - spreading plate structure.

[0023] Furthermore, the vacuum degree in the vacuum brazing furnace is better than 1×10 -2 Pa, and the brazing gap during the brazing process is not greater than 0.05 mm.

[0024] The above - mentioned technical solutions of the present application have the following advantages:

[0025] For the vacuum - encapsulated graphene - titanium alloy composite heat - spreading plate structure and the preparation method provided by the present application, by placing the graphene plate in the groove in the center of the titanium alloy bottom plate, placing the intermediate layer on the upper surface of the titanium alloy bottom plate, coaxially arranging the titanium alloy cover plate on the graphene plate, and using the vacuum brazing method to encapsulate the graphene plate in the groove between the titanium alloy cover plate and the titanium alloy bottom plate, graphene vacuum encapsulation can be realized, avoiding the problem of graphene oxidation during use; the thickness of the graphene plate is designed to be slightly higher than the depth of the groove, and pressure is applied during the brazing process, which can achieve a tight fit at the graphene / titanium alloy interface, reduce the interface thermal resistance, and improve the heat transfer efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] To more clearly illustrate the specific embodiments of the present application 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 application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0027] Figure 1 It is a schematic diagram of the composition of the vacuum-packaged graphene-titanium alloy composite heat spreader structure provided by the present application;

[0028] Figure 2 It is an isometric view of the vacuum-packaged graphene-titanium alloy composite heat spreader structure provided by the present application.

[0029] Reference numerals: 1, graphene plate; 2, titanium alloy cover plate; 3, titanium alloy bottom plate; 4, intermediate layer. Specific Embodiments

[0030] In the following description, specific details such as specific system structures and technologies are presented for the purpose of illustration rather than limitation, so as to thoroughly understand the embodiments of the present application. However, those skilled in the art should clearly understand that the present application can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and preparation methods are omitted to avoid unnecessary details from interfering with the description of the present application.

[0031] It should be understood that when used in the description of the present application specification and the appended claims, the term "comprising" indicates the presence of the described features, wholes, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0032] In addition, in the description of the present application specification and the appended claims, terms such as "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0033] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that specific features, structures or characteristics described in connection with that embodiment are included in one or more embodiments of this application. Thus, statements such as "in one embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments" etc. that appear in different places in this specification do not necessarily all refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized. The terms "comprising", "including", "having" and their variants all mean "including but not limited to", unless otherwise specifically emphasized. "Plurality" means "two or more".

[0034] Aiming at the problems of low interfacial strength of the conventional graphene-titanium alloy composite heat spreader and easy oxidation of graphene, this application proposes a vacuum-packaged graphene-titanium alloy composite heat spreader structure and a preparation method, solves the interfacial reaction problem and the graphene oxidation problem, and realizes the preparation of high-thermal-conductivity titanium-based composites.

[0035] The following will further describe in detail the specific implementation manners of this application in conjunction with the drawings and embodiments. The following embodiments are used to illustrate this application, but are not used to limit the scope of this application.

[0036] The embodiment of this application provides a vacuum-packaged graphene-titanium alloy composite heat spreader structure, which includes a graphene plate, a titanium alloy cover plate, a titanium alloy bottom plate, and an intermediate layer; a square groove is provided at the center of the titanium alloy bottom plate, the graphene plate is arranged in the groove, and the thickness of the graphene plate is higher than the depth of the groove; the intermediate layer is arranged on the upper surface of the titanium alloy bottom plate; there is a gap between the outer edge of the graphene plate and the inner wall of the groove, and the titanium alloy cover plate is coaxially arranged on the graphene plate; the titanium alloy cover plate and the titanium alloy bottom plate use vacuum brazing to encapsulate the graphene plate in the groove.

[0037] In some embodiments, the width between the inner edge of the groove and the outer edge of the titanium alloy bottom plate is not less than 10 mm.

[0038] In some embodiments, pure nickel coatings are prepared on the upper and lower surfaces of the graphene plate by magnetron sputtering.

[0039] In some embodiments, the thickness of the pure nickel coating is 5-10 μm.

[0040] In some embodiments, the intermediate layer is a foil-shaped titanium-based filler metal and is arranged on the upper surface of the titanium alloy bottom plate by resistance spot welding.

[0041] In some embodiments, the graphene plate is arranged at the center of the groove.

[0042] In some embodiments, the gap between the outer edge of the graphene plate and the inner wall of the groove is 2 to 3 mm.

[0043] In some embodiments, the upper surface of the graphene plate is 0.1 to 0.2 mm higher than the upper surface of the titanium alloy bottom plate.

[0044] Those skilled in the art can clearly understand that for the convenience and brevity of description, only the above-mentioned division of each functional unit and module is used as an example. In actual applications, the above functions can be allocated to different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. In addition, the specific names of each functional unit and module are only for the convenience of mutual distinction and do not limit the protection scope of the present application.

[0045] The embodiment of the present application also provides a preparation method for a vacuum-packaged graphene-titanium alloy composite heat spreader structure for preparing the vacuum-packaged graphene-titanium alloy composite heat spreader structure as described above; the preparation method of the vacuum-packaged graphene-titanium alloy composite heat spreader structure includes:

[0046] A square groove is prepared in the center of the titanium alloy bottom plate by mechanical processing, and the groove is coaxially arranged with the titanium alloy bottom plate;

[0047] The graphene plate is arranged in the groove, the thickness of the graphene plate is higher than the depth of the groove, and the intermediate layer is arranged on the upper surface of the titanium alloy bottom plate;

[0048] The titanium alloy cover plate is coaxially arranged on the graphene plate and pressed together to obtain a prefabricated welded part of the titanium alloy cover plate / intermediate layer / graphene plate / titanium alloy bottom plate composite structure;

[0049] The assembled prefabricated welded part is put into a vacuum brazing furnace for vacuum brazing to obtain a vacuum-packaged graphene-titanium alloy composite heat spreader structure.

[0050] In some embodiments, the vacuum degree in the vacuum brazing furnace is better than 1×10 -2 Pa, and the brazing gap during the brazing process is not greater than 0.05 mm.

[0051] The present application aims to solve the problems of low interfacial strength of existing graphene-titanium alloy composites and easy oxidation of graphene. At the same time, according to the structural characteristics, welding process and working characteristics of the vacuum-packaged graphene-titanium alloy composite heat spreader, a process plan for one-time integral brazing manufacturing is developed.

[0052] As Figure 1 and Figure 2 shown, the vacuum-packaged graphene-titanium alloy composite heat spreader provided by this application includes a graphene plate 1, a titanium alloy cover plate 2, a titanium alloy bottom plate 3, and an intermediate layer 4. A square groove is provided at the center of the titanium alloy bottom plate 3. The graphene plate 1 is disposed in the groove. The thickness of the graphene plate 1 is slightly higher than the depth of the groove. There is a gap between the outer edge of the graphene plate 1 and the inner wall of the groove. The titanium alloy cover plate 2 and the titanium alloy bottom plate 3 use vacuum brazing to encapsulate the graphene plate 1 in the groove.

[0053] The square groove of the titanium alloy bottom plate 3 is prepared by machining. The width of the inner edge of the groove from the outer edge of the bottom plate is not less than 10 mm. Pure nickel coatings are prepared on the upper and lower surfaces of the graphene plate 1 by magnetron sputtering, and the coating thickness is 5-10 μm; the intermediate layer 4 is a foil-shaped titanium-based filler metal, which is disposed on the upper surface of the bottom plate 3 by resistance spot welding. The graphene plate 1 is disposed at the center of the groove of the titanium alloy bottom plate 3. The gap between the outer edge of the graphene plate 1 and the inner edge of the groove is 2-3 mm, and the upper surface of the graphene plate 1 is 0.1-0.2 mm higher than the upper surface of the bottom plate 3.

[0054] The titanium alloy cover plate 2 is coaxially disposed on the graphene plate 1 to obtain a prefabricated welded part with a composite structure of titanium alloy cover plate 2 / intermediate layer 4 / graphene plate 1 / titanium alloy bottom plate 3. The assembled prefabricated welded part is placed in a vacuum brazing furnace for vacuum brazing to obtain a vacuum-packaged graphene / titanium alloy composite heat spreader. During brazing, the vacuum degree in the vacuum brazing furnace should be better than 1×10 -2 Pa, and sufficient pressure should be applied during the brazing process so that the brazing gap should not be greater than 0.05 mm.

[0055] The following is illustrated by specific examples.

[0056] Example 1

[0057] A vacuum-packaged graphene / TC4 titanium alloy composite heat spreader includes a graphene plate 1, a TC4 titanium alloy cover plate 2, a TC4 titanium alloy bottom plate 3, and a titanium-based filler metal 4. The size of the involved graphene plate is 100 mm×110 mm×0.6 mm; the size of the TC4 titanium alloy cover plate is 130 mm×140 mm×0.5 mm, and the size of the TC4 titanium alloy bottom plate is: outer frame 130 mm×140 mm, total thickness 1 mm, groove depth 0.5 mm, groove size 105 mm×115 mm; the titanium-based filler metal is a foil-shaped Ti-Zr-Cu-Ni filler metal.

[0058] The specific process of this example includes the following steps:

[0059] Step 1: Prepare a groove on the surface of the titanium alloy base plate 3 by machining. Specifically, the depth of the groove is 0.5 mm, the groove is coaxially arranged with the base plate, and the edge of the groove is 12.5 mm away from the edge of the base plate.

[0060] Step 2: Prepare pure nickel coatings on the upper and lower surfaces of the graphene plate 1 by magnetron sputtering. The thickness of the pure Ni coating is 5 - 8 μm.

[0061] Step 3: Remove the surface oxide layer from the surface of the titanium alloy cover plate 2 and the titanium alloy base plate 3 obtained in Step 1 by mechanical cleaning or chemical cleaning methods, and then fix the amorphous titanium-based solder foil tape on the upper surface of the titanium alloy base plate 3 by resistance spot welding.

[0062] Step 4: Coaxially arrange the nickel-coated graphene plate 1 in the groove of the titanium alloy base plate 3. The gap between the outer edge of the graphene plate 1 and the inner edge of the groove is 2.5 mm.

[0063] Step 5: Coaxially arrange the titanium alloy cover plate 2 on the graphene plate 1 and press it to obtain a prefabricated welded part with a composite structure of titanium alloy cover plate 2 / foil-shaped Ti-based solder 4 / graphene plate 1 / titanium alloy base plate 3.

[0064] Step 6: Put the assembled prefabricated welded part into a vacuum brazing furnace for vacuum brazing to obtain a graphene / TC4 titanium alloy composite heat spreader. Specifically, during brazing, the vacuum degree in the vacuum brazing furnace should be better than 1×10 -2 Pa, and a pressure not less than 1 MPa should be applied during the brazing process to make the brazing gap not greater than 0.05 mm.

[0065] After testing, the vacuum-packaged graphene / TC4 titanium alloy composite heat spreader has a thermal conductivity of 124.8 W / (m·K), and the thermal conductivity does not decrease significantly during use at 350°C.

[0066] Example 2

[0067] A vacuum-packaged graphene / Ti65 titanium alloy composite heat spreader includes a graphene plate 1, a Ti65 titanium alloy cover plate 2, a Ti65 titanium alloy base plate 3, and a Ti-based solder 4. The size of the involved graphene plate is 165 mm × 165 mm × 0.6 mm; the size of the Ti65 titanium alloy cover plate is 200 mm × 200 mm × 0.5 mm, and the size of the Ti65 titanium alloy base plate is: the outer frame is 200 mm × 200 mm, the total thickness is 1 mm, and the groove size is 170 mm × 170 mm × 0.5 mm; the Ti-based solder is a foil-shaped Ti-Zr-Cu-Ni-In solder.

[0068] The specific process of this example includes the following steps:

[0069] Step 1: Prepare a groove on the surface of the titanium alloy base plate 3 by mechanical machining. Specifically, the depth of the groove is 0.5 mm, the groove is coaxially arranged with the base plate, and the edge of the groove is 15 mm away from the edge of the base plate.

[0070] Step 2: Prepare pure nickel coatings on the upper and lower surfaces of the graphene plate 1 by magnetron sputtering. The thickness of the pure Ni coating is 5 - 8 μm.

[0071] Step 3: Use mechanical cleaning or chemical cleaning methods to remove the surface oxide layer on the surface of the titanium alloy cover plate 2 and the titanium alloy base plate 3 obtained in Step 1. Then, fix the amorphous Ti-based solder foil tape on the upper surface of the titanium alloy base plate 3 by resistance spot welding.

[0072] Step 4: Coaxially arrange the nickel-coated graphene plate 1 in the groove of the titanium alloy base plate 3. The gap between the outer edge of the graphene plate 1 and the inner edge of the groove is 2.5 mm.

[0073] Step 5: Coaxially arrange the titanium alloy cover plate 2 on the graphene plate 1 and press it to obtain a prefabricated welded part with a composite structure of titanium alloy cover plate 2 / foil-shaped Ti-based solder 4 / graphene plate 1 / titanium alloy base plate 3.

[0074] Step 6: Put the assembled prefabricated welded part into a vacuum brazing furnace for vacuum brazing to obtain a graphene / Ti65 titanium alloy composite heat spreader. Specifically, during brazing, the vacuum degree in the vacuum brazing furnace should be better than 1×10 -2 Pa, and a pressure not less than 1 MPa should be applied during the brazing process to make the brazing gap not greater than 0.05 mm.

[0075] After testing, for the vacuum-packaged graphene / Ti65 titanium alloy composite heat spreader, its thermal conductivity is 154.9 W / (m·K), and the thermal conductivity does not decrease significantly during use at 650°C.

[0076] For the vacuum-packaged graphene titanium alloy composite heat spreader structure and preparation method provided in the embodiments of the present application, plating a nickel layer on the surface of graphene can effectively control the interfacial reaction between graphene and titanium alloy, reduce the thickness of the TiC reaction layer, and ensure the thermal conductivity of the composite plate. Using the vacuum brazing method to connect the cover plate and the base plate can achieve the vacuum packaging of graphene and avoid the oxidation problem of graphene during use. The thickness of the graphene plate is designed to be slightly higher than the depth of the groove, and pressure is applied during the brazing process, which can achieve a tight fit at the graphene / titanium alloy interface, reduce the interfacial thermal resistance, and improve the heat transfer efficiency.

[0077] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it; although the present application 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 of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included within the protection scope of the present application.

Claims

1. A vacuum encapsulated graphene titanium alloy composite heat expansion plate structure, characterized in that: It includes a graphene plate, a titanium alloy cover plate, a titanium alloy bottom plate, and an intermediate layer; A square groove is provided in the center of the titanium alloy bottom plate, the graphene plate is arranged in the groove, and the thickness of the graphene plate is higher than the depth of the groove; the intermediate layer is arranged on the upper surface of the titanium alloy bottom plate; There is a gap between the outer edge of the graphene plate and the inner wall of the groove, and the titanium alloy cover plate is coaxially arranged on the graphene plate; the titanium alloy cover plate and the titanium alloy bottom plate are encapsulated in the groove by a vacuum brazing method.

2. The vacuum encapsulated graphene titanium alloy composite heat diffusion plate structure according to claim 1, characterized in that: The width of the inner edge of the groove from the outer edge of the titanium alloy bottom plate is not less than 10 mm.

3. The vacuum encapsulated graphene titanium alloy composite heat diffusion plate structure according to claim 1, characterized in that: The upper and lower surfaces of the graphene plate are prepared with pure nickel coating by magnetron sputtering.

4. The vacuum encapsulated graphene titanium alloy composite heat diffusion plate structure according to claim 3, characterized in that: The thickness of the pure nickel plating film is 5-10 μm.

5. The vacuum encapsulated graphene titanium alloy composite heat diffusion plate structure according to claim 1, characterized in that: The intermediate layer is a foil-shaped titanium-based brazing filler metal, which is arranged on the upper surface of the titanium alloy bottom plate by using a resistance spot welding method.

6. The vacuum encapsulated graphene titanium alloy composite heat diffusion plate structure according to claim 1, characterized in that: The graphene plate is disposed at the center of the groove.

7. The vacuum encapsulated graphene titanium alloy composite heat diffusion plate structure according to claim 1, characterized in that: The gap between the outer edge of the graphene plate and the inner wall of the groove is 2-3 mm.

8. The vacuum-encapsulated graphene titanium alloy composite heat diffusion plate structure according to claim 1, characterized in that: The upper surface of the graphene plate is 0.1 to 0.2 mm higher than the upper surface of the titanium alloy bottom plate.

9. A method for preparing a vacuum-encapsulated graphene titanium alloy composite heat expansion plate structure, characterized in that: Used to prepare the vacuum encapsulated graphene titanium alloy composite heat expansion plate structure according to any one of claims 1 to 8; The preparation method of the vacuum-encapsulated graphene titanium alloy composite heat expansion plate structure comprises: A square groove is prepared in the center of the titanium alloy bottom plate by a machining method, wherein the groove is coaxially arranged with the titanium alloy bottom plate; Disposing a graphene plate in the groove, wherein the thickness of the graphene plate is greater than the depth of the groove, and disposing an intermediate layer on the upper surface of the titanium alloy bottom plate; The titanium alloy cover plate is coaxially arranged on the graphene plate and pressed together to obtain a prefabricated weldment of a composite structure of titanium alloy cover plate / middle layer / graphene plate / titanium alloy bottom plate; The assembled prefabricated weldment is placed in a vacuum brazing furnace for vacuum brazing to obtain a vacuum-encapsulated graphene titanium alloy composite heat expansion plate structure.

10. The method for preparing the vacuum-encapsulated graphene titanium alloy composite heat diffusion plate structure according to claim 9, characterized in that: The vacuum degree in the vacuum brazing furnace is better than 1×10 -2 Pa, the brazing gap during brazing is not greater than 0.05mm.

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