A multilayer self-fusion graphene thermal conductive film and preparation method thereof

Abstract

The invention discloses a multilayer self-fusion graphene thermal conductive film and a preparation method thereof, belonging to the technical field of thermal conductive films. The preparation method of the invention can realize reduction and multilayer superposition in one step, and reducing sugar is added to graphene oxide slurry as a reducing agent and a binder, and the aldehyde group and the ketone group of the reducing sugar undergo redox reaction with the graphene oxide. During pressurized reduction, not only can a gas escape channel be generated in the process of reducing the graphene oxide, thereby avoiding the destruction of the membrane structure and the unevenness of the membrane surface caused by the concentrated and violent discharge of the gas generated in the reduction process, but also the gradual in-situ reduction reduces the phenomenon of extremely uneven membrane surface caused by the violent expansion in the reduction process, and at the same time avoids the loss of thermal conductivity caused by the wrinkles after large bubble rolling; the oxidation product of the reducing sugar forms a hydrogen bond connection with the graphene oxide, thereby enhancing the bonding force between the graphene oxide sheets, thereby realizing the assembly of a multilayer self-fusion ultra-thick graphene film with high thermal conductivity.

Description

Technical Field

[0001] The present invention relates to the technical field of graphene films, and in particular to a multilayer self-fusion graphene thermal conductive film and a preparation method thereof. Background Art

[0002] In recent years, with the rapid development of integrated circuits, electronic products have developed towards miniaturization, lightness, integration and high frequency, and their power density is getting higher and higher, which leads to heat accumulation in parts such as central processing units and communication basebands, thus affecting the performance of products and becoming a key issue restricting the development of many fields. Thermal management materials can assist equipment in heat dissipation, so as to maintain the working stability and reliability of equipment and extend the service life of equipment.

[0003] Graphene film has a large amount of sp 2 The hybridized carbon atoms form a skeleton, providing a good phonon transmission channel, giving it excellent thermal conductivity, making graphene thermal conductive film an ideal heat dissipation material. The heat expansion capacity of graphene thermal conductive film can be described according to the following Fourier thermal conductivity law:

[0004]

[0005] Among them, △T is the temperature difference, δ is the distance of heat conduction, K is the thermal conductivity of the thermal conductive material, A is the cross-sectional area of ​​the graphite film, S is the width of the graphite film, and h is the thickness of the graphite film. In actual use, because electronic products have fixed sizes, the thermal conductivity of the graphite film is directly related not only to the thermal conductivity but also to its thickness. For this reason, the design of a graphene thermal conductive film with excellent heat expansion capacity requires not only a high thermal conductivity, but also a certain thickness processability.

[0006] At present, the assembly of ultra-thick graphene thermal conductive films is mainly achieved from two aspects: increasing the concentration of graphene oxide slurry and bonding multilayer films through adhesives. However, increasing the concentration of graphene oxide slurry will not only make the process more complicated, but also the obtained graphene oxide film is prone to cracking during the drying process; in addition, the thickness of the graphene film obtained by increasing the concentration of graphene oxide slurry is also limited. The thick film obtained by bonding multilayer films not only has a high interfacial thermal resistance, which causes a sharp decrease in thermal conductivity, but also the adhesive is usually toxic, and the technology is time-consuming and has low production efficiency, which restricts its application in the market; in addition, the decomposition of the oxygen-containing functional groups of graphene oxide during the heat treatment process will release gas, resulting in the expansion of the film structure, and the ultra-thick graphene thermal conductive film will produce more gas, which will produce greater pressure and easily cause the film to crack. To this end, the present invention provides a multilayer self-fusion graphene thermal conductive film and a preparation method thereof. Summary of the invention

[0007] The present invention provides a multilayer self-fusion graphene thermal conductive film and a preparation method thereof, which effectively solves the technical problems in the prior art of complex graphene film process, limited thickness, easy cracking when drying, layer-by-layer coupling and excessive expansion of graphene, and also provides an ultra-thick high thermal conductive graphene film.

[0008] The present invention provides a method for preparing a multilayer self-fusion graphene thermal conductive film, which is characterized by comprising the following steps:

[0009] S1, adding reducing sugar to graphene oxide slurry to obtain pre-reduced graphene oxide slurry;

[0010] S2, pouring the pre-reduced graphene oxide slurry of S1 onto the substrate, coating it into a film, and drying it to obtain a pre-reduced graphene oxide film;

[0011] S3, stacking the pre-reduced graphene oxide film of S2 in multiple layers, reducing it under pressure, and graphitizing it in an argon atmosphere to obtain a graphitized film;

[0012] S4, rolling and calendering the graphitized film of S3 to obtain a graphene thermal conductive film.

[0013] Preferably, the reducing sugar includes glucose, fructose, galactose, lactose, maltose, and ascorbic acid.

[0014] Preferably, in S1, the concentration of the graphene oxide slurry is 10 to 20 mg / L.

[0015] Preferably, in S1, the mass ratio of graphene oxide to reducing sugar is 1:0.2-3.

[0016] Preferably, in S3, during the pressurized reduction, the temperature is 60-100° C., the pressure is 2-8 MPa, and the time is 0.5-2 h.

[0017] Preferably, in S3, the graphitization procedure is: heating to 2600-3000° C. at a rate of 1-10° C. / min and keeping the temperature for 30-120 min.

[0018] Preferably, in S2, the thickness of the pre-reduced graphene oxide film is 60 to 100 μm.

[0019] Preferably, in S3, the multi-layer stacking is 3 to 30 layers.

[0020] The present invention also provides a multilayer self-fusion graphene thermal conductive film prepared by the above preparation method.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The preparation method of the multi-layer self-fusion graphene thermal conductive film provided by the present invention can realize the superposition of reduction and multi-layer self-fusion in one step. The reducing sugar added to the graphene oxide slurry acts as a reducing agent and a binder at the same time. The aldehyde group and ketone group of the reducing sugar undergo a redox reaction with the graphene oxide. During the pressurized reduction, not only can a gas escape channel be generated during the reduction of the graphene oxide, thereby avoiding the destruction of the membrane structure caused by the concentrated and violent discharge of gas during the reduction process, but also the gradual in-situ reduction reduces the phenomenon of extremely uneven membrane surface caused by the violent expansion during the reduction process, and at the same time avoids the loss of thermal conductivity caused by wrinkles after large bubble rolling; hydrogen bonds are formed between the oxidation products of the reducing sugar and between the oxidation products of the reducing sugar and the graphene oxide, thereby enhancing the bonding force between the graphene oxide sheets, thereby realizing the assembly of a high thermal conductivity multi-layer self-fusion ultra-thick graphene film.

[0023] (2) The density and thermal conductivity of the multilayer self-fused graphene thermal conductive film prepared by the present invention are respectively 1.91-2.10 g / cm 3 and 951.6~1286.3W / (m·K).

[0024] (3) The preparation method of the multilayer self-fusion graphene thermal conductive film provided by the present invention is highly practical and simple to operate, and effectively solves the technical problems of the prior art such as the complex process flow of the graphene film, limited thickness, easy cracking during drying, and graphene layer-by-layer coupling and excessive expansion. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a process flow chart of the multi-layer self-fusion graphene thermal conductive film of the present invention;

[0026] Figure 2 is a SEM cross-sectional view of the multilayer self-fusion graphene thermal conductive film prepared in Example 5 of the present invention;

[0027] Figure 3 This is the XRD diagram of the multilayer self-fusion graphene thermal conductive film of Example 5 of the present invention. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solution of the present invention and implement it, the present invention is further described below in conjunction with specific examples, but the examples are not intended to limit the present invention. The following test methods and detection methods, unless otherwise specified, are conventional methods; the reagents and raw materials, unless otherwise specified, are commercially available.

[0029] Example 1

[0030] A method for preparing a multilayer self-fusion graphene thermal conductive film, such as Figure 1 As shown, the following steps are included:

[0031] S1, adding reducing sugar to a graphene oxide slurry having a concentration of 10 mg / L according to a mass ratio of graphene oxide to reducing sugar of 1:0.2 to obtain a pre-reduced graphene oxide slurry;

[0032] The reducing sugar is glucose;

[0033] S2, pouring the pre-reduced graphene oxide slurry of S1 on a polytetrafluoroethylene substrate, coating it into a film, and drying it to obtain a pre-reduced graphene oxide film with a thickness of 40 μm;

[0034] S3, stacking two layers of the pre-reduced graphene oxide film of S2, reducing them under pressure (temperature of 100° C., pressure of 8 MPa, time of 0.5 h), and graphitizing them under an argon atmosphere to obtain a graphitized film;

[0035] The graphitization procedure is as follows: heating to 2600°C at a rate of 10°C / min and keeping the temperature for 30min;

[0036] S4, rolling and calendering the graphitized film of S3 to obtain a graphene thermal conductive film.

[0037] Example 2

[0038] A method for preparing a multilayer self-fusion graphene thermal conductive film comprises the following steps:

[0039] S1, adding reducing sugar to a graphene oxide slurry having a concentration of 15 mg / L according to a mass ratio of graphene oxide to reducing sugar of 1:0.5 to obtain a pre-reduced graphene oxide slurry;

[0040] The reducing sugar is fructose;

[0041] S2, pouring the pre-reduced graphene oxide slurry of S1 on a polytetrafluoroethylene substrate, coating it into a film, and drying it to obtain a pre-reduced graphene oxide film with a thickness of 90 μm;

[0042] S3, stacking three layers of the pre-reduced graphene oxide film of S2, reducing them under pressure (temperature of 80° C., pressure of 6 MPa, time of 0.5 h), and graphitizing them under an argon atmosphere to obtain a graphitized film;

[0043] The graphitization procedure is as follows: heating to 2600°C at a rate of 5°C / min and keeping the temperature for 30min;

[0044] S4, rolling and calendering the graphitized film of S3 to obtain a graphene thermal conductive film.

[0045] Example 3

[0046] A method for preparing a multilayer self-fusion graphene thermal conductive film comprises the following steps:

[0047] S1, adding reducing sugar to a graphene oxide slurry having a concentration of 20 mg / L according to a mass ratio of graphene oxide to reducing sugar of 1:1 to obtain a pre-reduced graphene oxide slurry;

[0048] The reducing sugar is galactose;

[0049] S2, pouring the pre-reduced graphene oxide slurry of S1 on a polytetrafluoroethylene substrate, coating it into a film, and drying it to obtain a pre-reduced graphene oxide film with a thickness of 100 μm;

[0050] S3, stacking 5 layers of the pre-reduced graphene oxide film of S2, reducing under pressure (temperature of 60° C., pressure of 4 MPa, time of 1.5 h), and graphitizing under an argon atmosphere to obtain a graphitized film;

[0051] The graphitization procedure is as follows: heating to 2800°C at a rate of 2°C / min and keeping the temperature for 60min;

[0052] S4, rolling and calendering the graphitized film of S3 to obtain a graphene thermal conductive film.

[0053] Example 4

[0054] A method for preparing a multilayer self-fusion graphene thermal conductive film comprises the following steps:

[0055] S1, adding reducing sugar to a graphene oxide slurry having a concentration of 20 mg / L according to a mass ratio of graphene oxide to reducing sugar of 1:2 / 3 (i.e., the mass of reducing sugar is 1.5 times that of graphene oxide slurry) to obtain a pre-reduced graphene oxide slurry;

[0056] The reducing sugar is lactose;

[0057] S2, pouring the pre-reduced graphene oxide slurry of S1 on a polytetrafluoroethylene substrate, coating it into a film, and drying it to obtain a pre-reduced graphene oxide film with a thickness of 100 μm;

[0058] S3, stacking 8 layers of the pre-reduced graphene oxide film of S2, reducing under pressure (temperature of 60° C., pressure of 4 MPa, time of 2 h), and graphitizing under an argon atmosphere to obtain a graphitized film;

[0059] The graphitization procedure is: heating to 2800°C at a rate of 2°C / min and keeping the temperature for 90min;

[0060] S4, rolling and calendering the graphitized film of S3 to obtain a graphene thermal conductive film.

[0061] Example 5

[0062] A method for preparing a multilayer self-fusion graphene thermal conductive film comprises the following steps:

[0063] S1, adding reducing sugar to a graphene oxide slurry having a concentration of 20 mg / L according to a mass ratio of graphene oxide to reducing sugar of 1:2 / 3 (i.e., the mass of reducing sugar is 1.5 times that of graphene oxide slurry) to obtain a pre-reduced graphene oxide slurry;

[0064] The reducing sugar is maltose;

[0065] S2, pouring the pre-reduced graphene oxide slurry of S1 on a polytetrafluoroethylene substrate, coating it into a film, and drying it to obtain a pre-reduced graphene oxide film with a thickness of 100 μm;

[0066] S3, stacking 10 layers of the pre-reduced graphene oxide film of S2, reducing under pressure (temperature of 80° C., pressure of 4 MPa, time of 2 h), and graphitizing under an argon atmosphere to obtain a graphitized film;

[0067] The graphitization procedure is: heating to 3000°C at a rate of 1°C / min and keeping the temperature for 120min;

[0068] S4, the graphitized film of S3 is rolled and then rolled to obtain a graphene thermal conductive film, the SEM cross-sectional view of which is shown in FIG. Figure 2 As shown, the XRD pattern is Figure 3 shown.

[0069] Example 6

[0070] A method for preparing a multilayer self-fusion graphene thermal conductive film comprises the following steps:

[0071] S1, adding reducing sugar to a graphene oxide slurry having a concentration of 20 mg / L according to a mass ratio of graphene oxide to reducing sugar of 1:2 to obtain a pre-reduced graphene oxide slurry;

[0072] The reducing sugar is ascorbic acid;

[0073] S2, pouring the pre-reduced graphene oxide slurry of S1 on a polytetrafluoroethylene substrate, coating it into a film, and drying it to obtain a pre-reduced graphene oxide film with a thickness of 100 μm;

[0074] S3, stacking 15 layers of the pre-reduced graphene oxide film of S2, reducing under pressure (temperature of 80° C., pressure of 2 MPa, time of 2 h), and graphitizing under an argon atmosphere to obtain a graphitized film;

[0075] The graphitization procedure is: heating to 3000°C at a rate of 1°C / min and keeping the temperature for 120min;

[0076] S4, rolling and calendering the graphitized film of S3 to obtain a graphene thermal conductive film.

[0077] Example 7

[0078] A method for preparing a multilayer self-fusion graphene thermal conductive film comprises the following steps:

[0079] S1, adding reducing sugar to a graphene oxide slurry having a concentration of 20 mg / L according to a mass ratio of graphene oxide to reducing sugar of 1:2 to obtain a pre-reduced graphene oxide slurry;

[0080] The reducing sugar is fructose;

[0081] S2, pouring the pre-reduced graphene oxide slurry of S1 on a polytetrafluoroethylene substrate, coating it into a film, and drying it to obtain a pre-reduced graphene oxide film with a thickness of 100 μm;

[0082] S3, stacking 20 layers of the pre-reduced graphene oxide film of S2, reducing under pressure (temperature of 100° C., pressure of 2 MPa, time of 2 h), and graphitizing under an argon atmosphere to obtain a graphitized film;

[0083] The graphitization procedure is: heating to 3000°C at a rate of 1°C / min and keeping the temperature for 120min;

[0084] S4, rolling and calendering the graphitized film of S3 to obtain a graphene thermal conductive film.

[0085] Example 8

[0086] A method for preparing a multilayer self-fusion graphene thermal conductive film comprises the following steps:

[0087] S1, adding reducing sugar to a graphene oxide slurry having a concentration of 20 mg / L according to a mass ratio of graphene oxide to reducing sugar of 1:2 to obtain a pre-reduced graphene oxide slurry;

[0088] The reducing sugar is lactose;

[0089] S2, pouring the pre-reduced graphene oxide slurry of S1 on a polytetrafluoroethylene substrate, coating it into a film, and drying it to obtain a pre-reduced graphene oxide film with a thickness of 100 μm;

[0090] S3, stacking 30 layers of the pre-reduced graphene oxide film of S2, reducing under pressure (temperature of 100° C., pressure of 2 MPa, time of 2 h), and graphitizing under an argon atmosphere to obtain a graphitized film;

[0091] The graphitization procedure is: heating to 3000°C at a rate of 1°C / min and keeping the temperature for 120min;

[0092] S4, rolling and calendering the graphitized film of S3 to obtain a graphene thermal conductive film.

[0093] Example 9

[0094] A method for preparing a multilayer self-fusion graphene thermal conductive film comprises the following steps:

[0095] S1, adding reducing sugar to a graphene oxide slurry having a concentration of 20 mg / L according to a mass ratio of graphene oxide to reducing sugar of 1:3 to obtain a pre-reduced graphene oxide slurry;

[0096] The reducing sugar is glucose;

[0097] S2, pouring the pre-reduced graphene oxide slurry of S1 on a polytetrafluoroethylene substrate, coating it into a film, and drying it to obtain a pre-reduced graphene oxide film with a thickness of 100 μm;

[0098] S3, stacking 20 layers of the pre-reduced graphene oxide film of S2, reducing under pressure (temperature of 100° C., pressure of 2 MPa, time of 2 h), and graphitizing under an argon atmosphere to obtain a graphitized film;

[0099] The graphitization procedure is: heating to 3000°C at a rate of 1°C / min and keeping the temperature for 120min;

[0100] S4, rolling and calendering the graphitized film of S3 to obtain a graphene thermal conductive film.

[0101] Example 10

[0102] A method for preparing a multilayer self-fusion graphene thermal conductive film comprises the following steps:

[0103] S1, adding reducing sugar to a graphene oxide slurry having a concentration of 20 mg / L according to a mass ratio of graphene oxide to reducing sugar of 1:3 to obtain a pre-reduced graphene oxide slurry;

[0104] The reducing sugar is ascorbic acid;

[0105] S2, pouring the pre-reduced graphene oxide slurry of S1 on a polytetrafluoroethylene substrate, coating it into a film, and drying it to obtain a pre-reduced graphene oxide film with a thickness of 100 μm;

[0106] S3, stacking 30 layers of the pre-reduced graphene oxide film of S2, reducing under pressure (temperature of 100° C., pressure of 2 MPa, time of 2 h), and graphitizing under an argon atmosphere to obtain a graphitized film;

[0107] The graphitization procedure is: heating to 3000°C at a rate of 1°C / min and keeping the temperature for 120min;

[0108] S4, rolling and calendering the graphitized film of S3 to obtain a graphene thermal conductive film.

[0109] In order to further illustrate the effect of the present invention, the present invention also sets a comparative example, as follows:

[0110] Comparative Example 1 (no reducing sugar added)

[0111] A method for preparing a multilayer self-fusion graphene thermal conductive film comprises the following steps:

[0112] S1, preparing a graphene oxide slurry with a concentration of 20 mg / L without adding reducing sugar;

[0113] S2, pouring the graphene oxide slurry of S1 on a polytetrafluoroethylene substrate, coating it into a film, and drying it to obtain a graphene oxide film with a thickness of 100 μm;

[0114] S3, stacking 30 layers of the graphene oxide film of S2, reducing under pressure (temperature of 100° C., pressure of 2 MPa, time of 2 h), and graphitizing under an argon atmosphere to obtain a graphitized film;

[0115] The graphitization procedure is: heating to 3000°C at a rate of 1°C / min and keeping the temperature for 120min;

[0116] S4, rolling and calendering the graphitized film of S3 to obtain a graphene thermal conductive film.

[0117] Comparative Example 2 (no pressure reduction)

[0118] A method for preparing a multilayer self-fusion graphene thermal conductive film comprises the following steps:

[0119] S1, adding reducing sugar to a graphene oxide slurry having a concentration of 20 mg / L according to a mass ratio of graphene oxide to reducing sugar of 1:2 to obtain a pre-reduced graphene oxide slurry;

[0120] The reducing sugar is lactose;

[0121] S2, pouring the pre-reduced graphene oxide slurry of S1 on a polytetrafluoroethylene substrate, coating it into a film, and drying it to obtain a pre-reduced graphene oxide film with a thickness of 100 μm;

[0122] S3, stacking 30 layers of the pre-reduced graphene oxide film of S2, reducing without pressure (temperature is 100° C., without pressure, time is 2 h), and graphitizing under argon atmosphere to obtain a graphitized film;

[0123] The graphitization procedure is: heating to 3000°C at a rate of 1°C / min and keeping the temperature for 120min;

[0124] S4, rolling and calendering the graphitized film of S3 to obtain a graphene thermal conductive film.

[0125] Comparative Example 3 (Changing the pressure during pressurized reduction)

[0126] A method for preparing a multilayer self-fusion graphene thermal conductive film comprises the following steps:

[0127] S1, adding reducing sugar to a graphene oxide slurry having a concentration of 20 mg / L according to a mass ratio of graphene oxide to reducing sugar of 1:2 to obtain a pre-reduced graphene oxide slurry;

[0128] The reducing sugar is lactose;

[0129] S2, pouring the pre-reduced graphene oxide slurry of S1 on a polytetrafluoroethylene substrate, coating it into a film, and drying it to obtain a pre-reduced graphene oxide film with a thickness of 100 μm;

[0130] S3, stacking 30 layers of the pre-reduced graphene oxide film of S2, reducing under pressure (temperature of 60° C., pressure of 0.2 MPa, time of 0.5 h), and graphitizing under an argon atmosphere to obtain a graphitized film;

[0131] The graphitization procedure is: heating to 3000°C at a rate of 1°C / min and keeping the temperature for 120min;

[0132] S4, rolling and calendering the graphitized film of S3 to obtain a graphene thermal conductive film.

[0133] The thickness, density and thermal conductivity of the multilayer self-fused graphene thermal conductive films obtained in Examples 1 to 10 of the present invention and Comparative Examples 1 to 3 were tested respectively. The test results are shown in Table 1.

[0134] Table 1 Performance test table of multi-layer self-fusion graphene thermal conductive film

[0135]

[0136]

[0137] It can be seen from Table 1 that the thickness and thermal conductivity of the ultra-thick graphene thermally conductive film prepared by the preparation method of the multilayer self-fusion graphene thermally conductive film provided by the present invention can reach 621 μm and 1286.3 W / (m·K), respectively, while in Comparative Example 1, no reducing sugar is added, Comparative Example 2 is not pressurized reduction is performed, and Comparative Example 3 reduces the pressure during pressurized reduction, and the thermal conductivities of the graphene thermally conductive films prepared are only 468.6 W / (m·K), 485.2 W / (m·K), and 536.5 W / (m·K), respectively.

[0138] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a multilayer self-fusion graphene thermal conductive film, characterized in that: The following steps are involved: S1, adding reducing sugar to graphene oxide slurry to obtain pre-reduced graphene oxide slurry; the mass ratio of graphene oxide to reducing sugar is 1:0.2-3; the reducing sugar includes glucose, fructose, galactose, lactose, maltose, and ascorbic acid; S2, pouring the pre-reduced graphene oxide slurry of S1 onto the substrate, coating it into a film, and drying it to obtain a pre-reduced graphene oxide film; S3, stacking the pre-reduced graphene oxide film of S2 in multiple layers, reducing it under pressure, and graphitizing it in an argon atmosphere to obtain a graphitized film; during the pressure reduction, the temperature is 60-100°C, the pressure is 2-8MPa, and the time is 0.5-2h; S4, rolling and calendering the graphitized film of S3 to obtain a multilayer self-fusion graphene thermal conductive film; the density and thermal conductivity of the multilayer self-fusion graphene thermal conductive film are 1.91-2.10 g / cm 3 and 951.6~1286.3W / (m·K).

2. The method for preparing the multilayer self-fusion graphene thermal conductive film according to claim 1, characterized in that: In S1, the concentration of the graphene oxide slurry is 10-20 mg / L.

3. The method for preparing the multilayer self-fusion graphene thermal conductive film according to claim 1, characterized in that: In S3, the graphitization procedure is: heating to 2600-3000°C at a rate of 1-10°C / min and keeping the temperature for 30-120min.

4. The method for preparing the multilayer self-fusion graphene thermal conductive film according to claim 1, characterized in that: In S2, the thickness of the pre-reduced graphene oxide film is 60-100 μm.

5. The method for preparing a multilayer self-fusion graphene thermally conductive film according to claim 1, characterized in that: In S3, the multi-layer stacking is 3 to 30 layers.

6. A multilayer self-fusion graphene thermal conductive film prepared according to the preparation method according to any one of claims 1 to 5, characterized in that: The density and thermal conductivity of the multilayer self-fusion graphene thermal conductive film are 1.91-2.10 g / cm 3 and 951.6~1286.3W / (m·K).

Images