Graphene temperature balancing plate and preparation method thereof

Abstract

The present invention discloses a method for preparing a graphene temperature-averaging plate and a graphene temperature-averaging plate prepared by the method. The graphene temperature-averaging plate includes two metal layers and a composite core layer embedded between the two metal layers, the composite core layer includes a plurality of low-temperature alloy layers and graphene layers stacked at intervals, the metal layer is in direct contact with the low-temperature alloy layer; the melting point of the low-temperature alloy layer is 150°C-500°C, and the melting point of the metal layer is higher than the melting point of the low-temperature alloy layer. In the graphene temperature-averaging plate of the present invention, the low-temperature alloy layer is arranged between the graphene layer and the metal layer, which can act as a thermal interface material, reduce contact thermal resistance, and promote heat conduction. Furthermore, the low-temperature alloy layer is arranged between the graphene layers, and the graphene layers can be better stacked on each other by adjusting the wettability between the materials to further improve the thermal conductivity. At the same time, the low-temperature alloy layer can act as a solder, adjusting various metal components, so that its welding process is more diversified due to demand.

Description

Technical Field

[0001] The present invention belongs to the field of thermal management, and in particular relates to a graphene temperature balancing plate and a preparation method thereof. Background Art

[0002] As a new material with excellent thermal conductivity, graphene has attracted widespread attention in the field of electronic information materials since its discovery. As a solution for efficient heat dissipation and lightweight device development, more and more products use graphene heat dissipation film for integrated heat dissipation and electrical conductivity.

[0003] The thermal conductivity of conventional graphene heat dissipation film can also reach 1500W·m -1 ·K -1 , the thermal conductivity is far superior to that of metal materials (150-400W·m -1 ·K -1 ). There are also some studies on existing graphene aluminum composite materials, and graphene aluminum temperature balancing plates are also prepared, such as publication numbers CN 117756529A and CN116903385A. However, the composite of graphene layers and the interface bonding between graphene layers and aluminum, as well as the welding process, still have certain restrictions on the overall thermal conductivity. Summary of the invention

[0004] Based on the above problems, the present invention provides a graphene temperature balancing plate including a graphene layer with high thermal conductivity and low density and a preparation method thereof.

[0005] The present invention provides a graphene temperature equalizing plate, comprising two metal layers and a composite core layer embedded between the two metal layers, the composite core layer comprising a plurality of low-temperature alloy layers and a graphene layer stacked at intervals, the metal layer being in direct contact with the low-temperature alloy layer; the melting point of the low-temperature alloy layer is 150°C-500°C, and the melting point of the metal layer is higher than the melting point of the low-temperature alloy layer.

[0006] According to an embodiment of the present invention, the low-temperature alloy layer includes an alloy consisting of two or more metals selected from the group consisting of indium, bismuth, tin, copper, aluminum, and nickel.

[0007] According to another embodiment of the present invention, the low-temperature alloy layer is at least partially embedded in the graphene layer.

[0008] According to another embodiment of the present invention, the metal layer is an aluminum layer, an aluminum alloy layer or a copper layer.

[0009] According to another embodiment of the present invention, the graphene temperature plate further comprises metal particles, which are at least partially embedded in the adjacent low-temperature alloy layer and the graphene layer. Preferably, the metal particles are one or more of copper particles, nickel particles and aluminum particles.

[0010] The present invention also provides a method for preparing the above-mentioned graphene temperature equalizing plate, comprising: melting a low-temperature alloy and coating it on the surface of the graphene layer to form a first composite structure consisting of a plurality of low-temperature alloy layers and the graphene layers stacked at intervals, wherein the two outer layers of the first composite structure are both the graphene layers; melting the low-temperature alloy and coating it on the surface of the metal layer, stacking the first composite structure and the metal layer coated with the low-temperature alloy to form a second composite structure; and hot pressing, vacuum hot pressing, brazing or vacuum diffusion welding the second composite structure to obtain the graphene temperature equalizing plate.

[0011] The present invention also provides a method for preparing the above-mentioned graphene temperature equalizing plate, comprising: mixing metal particles with molten low-temperature alloy, and coating the mixture on the surface of the graphene layer to form a first composite structure consisting of a plurality of spaced-apart stacked low-temperature alloy layers and the graphene layers, wherein the two outer layers of the first composite structure are both graphene layers; melting the low-temperature alloy and coating it on the surface of the metal layer, and then stacking the first composite structure and the metal layer coated with the low-temperature alloy to form a second composite structure; and hot pressing, vacuum hot pressing, brazing or vacuum diffusion welding the second composite structure to obtain the graphene temperature equalizing plate.

[0012] According to one embodiment of the present invention, before stacking to form the second composite structure, the process further includes: melting the low temperature alloy and coating it on the surface of the metal layer, and then placing the first composite structure between two metal layers coated with the low temperature alloy.

[0013] According to another embodiment of the present invention, after the low-temperature alloy is melted or the metal particles are mixed with the molten low-temperature alloy, the coating thickness is between 10-20 μm, and the thickness of the graphene layer is between 30-100 μm.

[0014] According to another embodiment of the present invention, before the metal layer forms a stacked structure, the contact surface between the metal layer and the low-temperature alloy layer is roughened and acid-treated.

[0015] According to another embodiment of the present invention, before forming the second composite structure, the first composite structure is further hot pressed, and the hot pressing temperature is 20-50 degrees lower than the melting point of the low-temperature alloy in the low-temperature alloy layer.

[0016] According to another embodiment of the present invention, when hot pressing or vacuum hot pressing is performed on the second composite structure, the hot pressing temperature is 15-20° C. higher than the melting point of the low temperature alloy.

[0017] In the graphene heat spreader of the present invention, the low-temperature alloy layer is arranged between the graphene layer and the metal layer, which can act as a thermal interface material, reduce contact thermal resistance, and promote heat conduction. Further, the low-temperature alloy layer is arranged between the graphene layers, and the graphene layers can be better laminated to each other by adjusting the wettability between the materials to further improve the thermal conductivity. At the same time, the low-temperature alloy layer can act as solder, and various metal components are adjusted to make its welding process more diversified due to demand. Further, it also includes metal particles partially embedded in the graphene layer and the low-temperature alloy layer, which can improve the conduction of heat between layers (vertical stacking direction), and further improve the thermal conductivity of the graphene heat spreader. Compared with the graphene heat conduction plate, the graphene heat spreader of the present invention can significantly improve the mechanical strength of the film, so that any size and any shape can be prepared, and the application range is wider. And the graphene heat spreader of the present invention includes a graphene layer that can significantly reduce the density of the graphene heat spreader, meeting the demand for heat conduction plates of lightweight devices.

[0018] The preparation method of the present invention firstly compounds the low melting point alloy with the graphene layer, adjusts the wettability between the low melting point alloy and the graphene layer, and can compound the graphene layer in multiple layers to achieve any thickness and any shape, and can also improve the mechanical properties of the graphene layer itself. Then, the inner surface of the metal layer is processed to adjust the wettability between the low melting point alloy and the metal layer, and the composite core layer and the metal layer are stacked, and the composite core layer and the metal layer are stacked according to different thermal conductivity requirements (400-800W·m -1 ·K -1 ), different packaging methods can be used, such as hot pressing, vacuum hot pressing, brazing, vacuum diffusion welding, etc. to form a graphene temperature plate, and the preparation is free and simple. In addition, by fusing irregularly shaped metal particles in a low-temperature alloy, the coating is evenly distributed during the coating process, and in the subsequent hot pressing process, the metal particles penetrate the graphene layer and act as rivets, which can simultaneously increase the interlayer bonding force and interlayer thermal conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the cross section of a graphene temperature equalizing plate according to one embodiment of the present invention.

[0020] Figure 2 This is an electron microscope photograph of a cross section of a graphene temperature-homogenizing plate according to one embodiment of the present invention.

[0021] The reference numerals are described as follows:

[0022] 10-graphene temperature equalizing plate; 11-metal layer; 12-composite core layer; 121-low temperature alloy layer; 122-graphene layer. DETAILED DESCRIPTION

[0023] The present invention is described in detail below in conjunction with specific implementation modes.

[0024] like Figure 1 As shown, the graphene temperature equalizer 10 of the present invention comprises two metal layers 11 and a composite core layer 12 embedded between the two metal layers 11, the composite core layer 12 comprises a plurality of low-temperature alloy layers 121 and graphene layers 122 which are stacked at intervals, the metal layer 11 is in direct contact with the low-temperature alloy layer 121; the melting point of the low-temperature alloy layer 121 is 150°C-500°C, and the melting point of the metal layer 11 is higher than the melting point of the low-temperature alloy layer 121. In the graphene temperature equalizer 10 of the present invention, the low-temperature alloy layer 121 is arranged between the graphene layer 122 and the metal layer 11, which can act as a thermal interface material, reduce contact thermal resistance, and promote heat conduction. Furthermore, the low-temperature alloy layer 121 is arranged between the graphene layers 122, and the graphene layers 122 can be better stacked on each other by adjusting the wettability between the materials, further improving the thermal conductivity and interlayer bonding strength. At the same time, the low-temperature alloy layer 121 can act as a hot pressing adhesive or solder for the two metal layers 11, adjusting various metal components to match the hot pressing or welding process. Compared with the graphene heat conducting plate, the graphene heat balancing plate 10 of the present invention can significantly improve the mechanical strength of the graphene layer, so it can be prepared in any size and any shape, and has a wider range of applications. And the graphene heat balancing plate 10 of the present invention includes a graphene layer 122, which can significantly reduce the density of the graphene heat balancing plate 10, meeting the demand for heat conducting plates of lightweight devices.

[0025] like Figure 1 As shown, it can be seen that the composite core layer 12 in the graphene temperature plate 10 of the present invention includes n graphene layers 122 and n+1 low-temperature alloy layers 121. The specific value of n can be selected according to actual needs. For example, n can be an integer from 1 to 100. For example, n can be 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, etc.

[0026] In an optional embodiment, the low-temperature alloys in each low-temperature alloy layer 121 in the composite core layer 12 are the same or different. The thickness of each low-temperature alloy layer 121 is the same or different. The thickness of each graphene layer 122 is the same or different.

[0027] In an optional embodiment, the low temperature alloy layer includes an alloy consisting of two or more metals selected from the group consisting of indium, bismuth, tin, copper, aluminum, and nickel.

[0028] In an optional embodiment, the graphene temperature plate further comprises metal particles, which are at least partially embedded in adjacent low-temperature alloy layers and graphene layers. The metal particles embedded in the low-temperature alloy layer and the graphene layer can act as rivets, further increasing the bonding force between the adjacent low-temperature alloy layer and the graphene layer. In addition, the metal particles can improve the conduction of heat between layers (vertical to the stacking direction), further improving the thermal conductivity of the graphene temperature plate. For example, the metal particles are one or more of copper particles, nickel particles, and aluminum particles.

[0029] In an optional embodiment, if Figure 2 As shown, the low temperature alloy layer is at least partially embedded in the graphene layer. The low temperature alloy layer can improve the interlayer bonding force by being embedded in the graphene layer, and improve the mechanical properties and interlayer thermal conductivity of the graphene temperature balancing plate.

[0030] In an optional embodiment, the metal layer is an aluminum layer, an aluminum alloy layer or a copper layer.

[0031] In an optional embodiment, the two metal layers are respectively a metal box with a cavity and a metal cover plate, and the metal box and the metal cover plate are combined to form a containing space for the composite core layer.

[0032] The thermal conductivity of the graphene temperature balancing plate of the present invention can reach 400-800 W·m -1 ·K -1 between.

[0033] The preparation method of the above-mentioned graphene temperature-averaging plate may include: melting a low-temperature alloy and coating it on the surface of a graphene layer to form a first composite structure consisting of a plurality of low-temperature alloy layers and graphene layers stacked at intervals, wherein both outer layers of the first composite structure are graphene layers; placing the first composite structure between two metal layers, stacking them to form a second composite structure; and hot pressing, vacuum hot pressing, brazing or vacuum diffusion welding the second composite structure to obtain a graphene temperature-averaging plate.

[0034] A method for preparing a graphene temperature-averaging plate containing metal particles may include: mixing the metal particles with a molten low-temperature alloy, and coating the mixture on the surface of a graphene layer to form a first composite structure consisting of a plurality of spaced-apart stacked low-temperature alloy layers and graphene layers, wherein both outer layers of the first composite structure are graphene layers; melting the low-temperature alloy and coating the mixture on the surface of a metal layer, and then stacking the first composite structure and the metal layer coated with the low-temperature alloy to form a second composite structure; and hot pressing, vacuum hot pressing, brazing or vacuum diffusion welding the second composite structure to obtain a graphene temperature-averaging plate.

[0035] The preparation method of the present invention firstly compounds the low melting point alloy with the graphene layer, adjusts the wettability between the low melting point alloy and the graphene layer, and can compound the graphene layer in multiple layers to achieve any thickness and any shape, and can also improve the mechanical properties of the graphene layer itself. Then, the inner surface of the metal aluminum layer is treated to adjust the wettability between the low melting point alloy and the aluminum, and the graphene layer is formed according to different thermal conductivity requirements (400-800W·m -1 ·K -1) and different application scenarios, select the appropriate low-temperature alloy, and select the appropriate packaging method accordingly. For example, hot pressing, vacuum hot pressing, brazing, vacuum diffusion welding, etc. When hot pressing, vacuum hot pressing, and vacuum diffusion welding are used, low-temperature alloys can be used as binders or solders; when brazing is used, appropriate solder needs to be added. Among them, the low-temperature alloy composition and content ratio can be comprehensively selected according to the specific thermal conductivity requirements, wettability with the graphene layer, and wettability with the encapsulation metal layer.

[0036] In an optional embodiment, before stacking to form the second composite structure, the method further includes: melting a low-temperature alloy and coating it on the inner surface of the metal layer, and placing the first composite structure between the two metal layers coated with the low-temperature alloy.

[0037] In an optional embodiment, the thickness of the low-temperature alloy after melting is between 10-20 μm, and the thickness of the graphene layer is between 30-100 μm. If the low-temperature alloy layer is too thin, the effect of bonding the upper and lower graphene layers is not good, and the surrounding gaps cannot be effectively filled during the hot pressing process. If it is too thick, the overall structure will be too heavy. The reasons for selecting the above thickness range for the graphene layer are similar.

[0038] In an optional embodiment, when the graphene temperature plate contains metal particles, the metal particles can be mixed with molten low-temperature alloy and then coated, so that the metal particles are partially embedded in the low-temperature alloy layer and protrude from the low-temperature alloy layer. During the hot pressing process, the metal particles can penetrate into the graphene layer, act as rivets, increase the interlayer bonding force, and improve the interlayer thermal conductivity.

[0039] In an optional embodiment, before the metal layer forms a stacked structure, the contact surface between the metal layer and the low-temperature alloy layer is roughened and acid-treated to improve the bonding force between the metal layer and the low-temperature alloy layer.

[0040] In an optional embodiment, before forming the second composite structure, the first composite structure is further subjected to hot pressing, and the hot pressing temperature is 20-50 degrees lower than the melting point of the low-temperature alloy in the low-temperature alloy layer, so as to avoid the hot pressing temperature being too high to reach above the melting point, which would cause the low-temperature metal to be lost during the hot pressing process, and fail to achieve the effect of hot pressing in improving the bonding strength between the two.

[0041] In an optional embodiment, when the second composite structure is packaged by hot pressing or vacuum hot pressing, the hot pressing temperature is 15-20° C. higher than the melting point of the low-temperature alloy. At this temperature, the low-temperature alloy melts, and a small amount of the fluid low-temperature alloy overflows to fill the surrounding gaps and package the two metal layers.

[0042] The present invention is further described below by specific examples. However, these examples are merely exemplary and do not constitute any limitation to the scope of the present invention. In the following examples and comparative examples, the reagents, materials and instruments used are all commercially available unless otherwise specified.

[0043] Example 1

[0044] Indium, bismuth and tin are placed in a melting furnace in a mass ratio of 1:3:16, vacuum melted at 300°C and stirred to obtain a low-temperature alloy material with a melting point of about 200°C.

[0045] Place the first graphene layer (200 mm long, 150 mm wide, 0.04 mm thick) flat on a heating table, heat to 200°C, and evenly apply the melted alloy on the graphene layer with a coating thickness of 10 μm. Then lay the second graphene layer flat on the low-temperature alloy layer. Repeat the above process to obtain a first composite structure with 26 graphene layers and 25 low-temperature alloy layers stacked. Then place the first composite structure on a hot press at 160°C and 40MPa for hot pressing.

[0046] The formed structure was cut into dimensions of 120 mm in length, 60 mm in width and 1.2 mm in thickness using a film cutter.

[0047] Prepare an aluminum box with a size of 150 mm in length, 75 mm in width, and 3.5 mm in thickness, wherein the size of the aluminum box cavity is 120 mm in length, 60 mm in width, and 2 mm in height. Roughen and pickle the aluminum box cavity. Prepare an aluminum cover plate with a size of 120 mm in length, 60 mm in width, and 1 mm in thickness, and roughen and pickle the inner side of the aluminum cover plate.

[0048] The bottom surface of the inner side of the aluminum box cavity and the inner side of the aluminum cover are coated with molten low-temperature alloy with a coating thickness of 10 μm. The hot-pressed first composite structure is placed in the aluminum box cavity, and the aluminum cover is placed on the composite structure.

[0049] Vacuum hot pressing (-0.05MPa temperature 220℃ pressure 50MPa) is used for hot pressing welding. Under high temperature hot pressing, a small amount of low-temperature alloy layer overflows, fills the surrounding gaps, and encapsulates the aluminum box cavity and the aluminum cover.

[0050] After mechanical polishing and surface treatment, a graphene temperature-averaging plate (150 mm long, 75 mm wide, and 3.5 mm thick) was finally obtained.

[0051] Test thermal conductivity: The national standard ASTMD5470-01 is used to test thermal conductivity, and the thermal conductivity equivalent is 480W / mK.

[0052] Example 2

[0053] Only the low temperature alloy is replaced with tin and bismuth in a mass ratio of 4:1. Others are the same as in Example 1.

[0054] The thermal conductivity equivalent of the graphene temperature equalizing plate prepared in this embodiment is tested to be 410 W / mK.

[0055] Example 3

[0056] Except that the low temperature alloy layer contains copper particles, the other aspects are the same as Example 1. Specifically, the low temperature alloy is melted at 220° C., irregularly shaped copper particles (about 40 μm) are added at a mass ratio of 3.3:1, and stirred and mixed to form a low temperature alloy-copper mixture.

[0057] The thermal conductivity equivalent of the graphene temperature equalizing plate prepared in this embodiment is tested to be 630 W / mK.

[0058] Comparative Example 1

[0059] The aluminum plate with a length of 150mm, a width of 75mm and a thickness of 3.5mm has a thermal conductivity equivalent of 180W / mK.

[0060] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A graphene temperature balancing plate, characterized in that: It comprises two metal layers and a composite core layer embedded between the two metal layers, wherein the composite core layer comprises a plurality of low-temperature alloy layers and graphene layers stacked at intervals, and the metal layer is in direct contact with the low-temperature alloy layer; the melting point of the low-temperature alloy layer is 150°C-500°C, and the melting point of the metal layer is higher than the melting point of the low-temperature alloy layer.

2. The graphene temperature equalizing plate according to claim 1, characterized in that: The low temperature alloy layer includes an alloy consisting of two or more metals selected from the group consisting of indium, bismuth, tin, copper, aluminum and nickel.

3. The graphene temperature equalizing plate according to claim 1, characterized in that: The low temperature alloy layer is at least partially embedded in the graphene layer.

4. The graphene temperature equalizing plate according to claim 1, characterized in that: The metal layer is an aluminum layer, an aluminum alloy layer or a copper layer.

5. The graphene temperature equalizing plate according to claim 1, characterized in that: The graphene temperature homogenizing plate further includes metal particles, which are at least partially embedded in the adjacent low-temperature alloy layer and the graphene layer.

6. The graphene temperature equalizing plate according to claim 5, characterized in that: The metal particles are one or more of copper particles, nickel particles and aluminum particles.

7. A method for preparing the graphene temperature balancing plate according to any one of claims 1 to 4, characterized in that: include: Melting a low-temperature alloy and coating it on the surface of the graphene layer to form a first composite structure consisting of a plurality of low-temperature alloy layers and the graphene layers stacked at intervals, wherein both outer layers of the first composite structure are the graphene layers; placing the first composite structure between two metal layers to form a second composite structure; and The second composite structure is subjected to hot pressing, vacuum hot pressing, brazing or vacuum diffusion welding to obtain the graphene temperature balancing plate.

8. A method for preparing the graphene temperature balancing plate according to claim 5 or 6, characterized in that: include: After mixing metal particles with molten low-temperature alloy, coating the mixture on the surface of the graphene layer to form a first composite structure consisting of a plurality of low-temperature alloy layers and graphene layers stacked at intervals, wherein both outer layers of the first composite structure are the graphene layers; placing the first composite structure between two metal layers to form a second composite structure; and The second composite structure is subjected to hot pressing, vacuum hot pressing, brazing or vacuum diffusion welding to obtain the graphene temperature balancing plate.

9. The preparation method according to claim 7 or 8, characterized in that: Before stacking to form the second composite structure, the method further includes: melting the low temperature alloy and coating it on the inner surface of the metal layer, and placing the first composite structure between two metal layers coated with the low temperature alloy.

10. The preparation method according to claim 7 or 8, characterized in that: After the low-temperature alloy is melted or the metal particles are mixed with the molten low-temperature alloy, the coating thickness is between 10-20 μm, and the thickness of the graphene layer is between 30-100 μm.

11. The preparation method according to claim 7 or 8, characterized in that: Before forming the second composite structure, the method further includes hot pressing the first composite structure, wherein the hot pressing temperature is 20-50 degrees lower than the melting point of the low-temperature alloy in the low-temperature alloy layer.

12. The preparation method according to claim 7 or 8, characterized in that: When hot pressing or vacuum hot pressing is performed on the second composite structure, the hot pressing temperature is 15-20° C. higher than the melting point of the low-temperature alloy.

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