Graphene micro-nano cavity heat conduction film and application thereof and graphene micro-nano cavity phase change vapor chamber

Abstract

The graphene micro-nano cavity heat conducting film has a thickness of 0.15-3 mm, achieves good heat conducting and electric conducting effects, and makes 80% of the rebound stress greater than or equal to 0.05 MPa. 2 The surface density of the graphene micro-nano cavity heat conducting film prepared by the application is 0.002 g / cm 2 ~0.2 g / cm 2 , which guarantees the application of the heat conducting film in pressure sensors, super capacitors, fuel cells, carbon catalytic materials, switches and optical modules. The graphene micro-nano cavity heat conducting film obtained by the application is composed of pure graphite components, has a fluffy and porous microstructure, and has uniform and stable performance. The graphene micro-nano cavity heat conducting film can also be used in combination with other materials in subsequent use, has a wide application range, a good prospect and diversified application fields, and is a rare high-heat-conducting and electrically-conducting material on the market.

Description

Technical Field

[0001] This invention belongs to the field of graphene technology, and particularly relates to graphene micro / nano cavity thermal conductive films and their applications, and graphene micro / nano cavity phase change heat spreaders. Background Technology

[0002] Graphene micro / nano cavity thermal conductive film is a thermal conductive and heat dissipation product made solely from graphene. Currently, there are many graphene thermal conductive films on the market, aiming to modify graphene materials to obtain products with good thermal conductivity for heat dissipation in electronic devices.

[0003] Chinese invention patent CN116691084A discloses a graphene thermal conductive film. In this patent, a thermally conductive product with high thermal conductivity and suitable thickness is obtained through modification with graphene, epoxy resin, glass fiber materials, and silane coupling agents. However, the addition of glass fiber and organic materials in this patent not only masks the inherent properties of graphene, but the use of adhesives in the thermal conductive film also leads to poor weather resistance over long-term use, affecting its application range. Furthermore, the use of adhesives places higher demands on the manufacturing process, and while increasing the thickness, it also reduces the prominence of graphene's properties, significantly limiting its use in products with high thermal conductivity requirements.

[0004] Therefore, given the current applications of graphene materials in heat conduction and heat dissipation, developing a product that uses graphene as a raw material and retains the original properties of graphene is a significant challenge. Summary of the Invention

[0005] The purpose of this invention is to provide a graphene micro-nano cavity thermal conductive film with a thickness between 0.15 and 3 mm, achieving good thermal and electrical conductivity, and ensuring that 80% of the rebound stress is ≥0.01 MPa.

[0006] To achieve the above objectives, a first aspect of the present invention provides a graphene micro / nano cavity thermal conductive film, which is obtained by coating graphene oxide, foaming, carbonizing, and graphitizing.

[0007] In some preferred embodiments, the thickness of the thermally conductive film is 0.15–3 mm, and examples include 0.15 mm, 0.18 mm, 0.2 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.63 mm, 0.65 mm, 0.68 mm, 0.7 mm, 0.74 mm, 0.78 mm, 0.82 mm, 0.85 mm, 0.9 mm, 0.95 mm, 0.98 mm, 1 mm, 1.5 mm, 1.8 mm, 1.9 mm, 2 mm, 2.2 mm, 2.5 mm, and 2.8 mm.

[0008] More preferably, the X-ray diffraction pattern of the thermally conductive film satisfies: 10° ≤ 2θ GFF -2θ GO ≤20°.

[0009] More preferably, the X-ray diffraction pattern of the thermally conductive film satisfies: 12°≤2θ GFF -2θ GO ≤17.5°.

[0010] X-ray diffraction testing method for thermal conductive films:

[0011] In this invention, the XRD (X-ray Diffraction) instrument can be a Japanese Rigaku Ultima IV, using a copper target as the test target, with a scanning range of 5-90° and a scanning speed of 10° / min as the excitation source to test the crystallinity of the sample.

[0012] In this invention, the degree of crystallinity change in graphene oxide after coating, foaming, carbonization, and graphitization directly affects the planar thermal conductivity of the final micro / nano cavity thermal conductive film. Through extensive testing and research, the inventors discovered that when the X-ray diffraction pattern of the thermal conductive film satisfies 10°≤2θ... GFF -2θ GO At ≤20°, the final micro / nano cavity thermal conductive film surface thermal diffusivity ≥500 mm can be achieved. 2 / s. The applicant speculates that this result is achieved because the crystallinity difference between graphene oxide and the micro / nano cavity thermal conductive film is small, and correspondingly, graphene oxide 2θ GO A relatively large value indicates a lower content of oxygen-containing functional groups in its structure, resulting in fewer atomic defects during the carbonization stage. Consequently, its atomic structure can be rapidly repaired during the graphitization stage, leading to high structural integrity and fast heat transfer rate in the resulting micro / nano cavity thermal conductive film. Furthermore, the inventors discovered that if 2θ GFF -2θ GO At temperatures above 20°C, the planar thermal conductivity of the micro / nano cavity thermal conductive film decreases. The applicant speculates that this is because of the significant difference in crystallinity between the two materials. Graphene oxide has a large number of oxygen-containing functional groups on its surface, resulting in numerous atomic defects during its carbonization stage. These defects cannot be completely repaired in time during the graphitization stage, and their presence directly affects heat transfer within the structure, leading to a significant decrease in the planar thermal conductivity of the micro / nano cavity thermal conductive film.

[0013] In some preferred embodiments, a foaming composition is used in the foaming process; the foaming composition is selected from at least one of hydrazine hydrate, sodium borate, dimethylhydrazine, and thiourea; preferably hydrazine hydrate.

[0014] More preferably, the mass concentration of the foaming composition is 0.05-80%, for example, 0.1%, 0.5%, 1%, 5%, 10%, 18%, 23%, 34%, 45%, 52%, 60%, 65%, 75%, etc.; more preferably, the mass concentration of the foaming composition is 1-10%, for example, 0.1%, 0.5%, 1%, 1.5%, 2%, 3%, 4%, 5%, 7%, 8%, 9%, 10%, etc.

[0015] In some preferred embodiments, the foaming process forms intermediate 1, and the peak areas of intermediate 1 in the XPS spectrum are related as follows: 20% ≤ AreaC-O / (AreaC-C+C=C) ≤ 60%, where AreaC-O and AreaC-C+C=C are the peak areas of C1s carbon-oxygen single bonds and carbon-carbon single bonds and carbon-carbon double bonds in the XPS spectrum, respectively.

[0016] In this invention, XPS (X-ray photoelectron spectroscopy) can be performed using a Thermo Scientific NEXSA XPS instrument, with the sample in a vacuum of approximately 5*10⁻⁶. -9 In the mbar analysis chamber, a monochromatic Al Kα source is used to test the chemical composition of the samples.

[0017] In this invention, residual O atoms remain in the intermediate 1 formed after foaming. Through extensive testing and research, the inventors discovered that when the intermediate 1 formed after foaming has an XPS spectrum of 20% ≤ AreaC-O / (AreaC-C+C=C) ≤ 60%, the final thermally conductive film can achieve a compressive resilience stress of 0.01–0.23 MPa at 80%. The applicant speculates that this phenomenon occurs because during the foaming process, the foaming composition can strongly interact with the oxygen atoms (mainly oxygen atoms in the CO structure) on the surface of graphene oxide, resulting in the large-scale conversion and generation of gases such as CO, CO2, and NH3, which accumulate in the interlayer of graphene. This leads to a rapid increase in local gas pressure, opening the interlayer and forming a porous structure. At the same time, stable hydrogen bonds are formed between the graphene atoms, ensuring the formation of stable micro-nano pores in the prepared thermally conductive film. When subjected to external compressive stress, its stable void structure can quickly disperse the stress, thereby ensuring that its resilience stress can reach 0.2 MPa. Furthermore, the inventors discovered that if AreaC-O / (AreaC-C+C=C) > 60% after foaming, it is speculated that during the foaming process, the interaction between the foaming composition and the oxygen atoms on the graphene oxide surface is weak, resulting in low gas conversion and insufficient local gas pressure. Consequently, the graphene layers are not fully opened, leading to poor pore structure formation. Correspondingly, fewer hydrogen bonds are formed between graphene layers, resulting in weak interlayer connections and stress concentration under external force, significantly reducing compression and rebound performance. Additionally, the inventors found that when AreaC-O / (AreaC-C+C=C) < 20% after foaming, the rebound stress is extremely low, below 0.01 MPa. This suggests that during the foaming process, the reaction between the foaming composition and the oxygen atoms on the graphene oxide surface is excessive, causing local gas pressure between graphene layers to exceed the graphene structure's tolerance, severely damaging the pore structure and preventing rebound after compression.

[0018] In some preferred embodiments, the carbon content of the graphene oxide is 60-70 wt%.

[0019] In this invention, the graphene oxide used was purchased from Yunnan Yuntian Morui Technology Co., Ltd.

[0020] In some preferred embodiments, the carbon content of the thermally conductive film obtained after graphitization is 1 to 2 times that of graphene oxide; more preferably, the carbon content of the thermally conductive film obtained after graphitization is 1.2 to 1.7 times that of graphene oxide.

[0021] In some preferred embodiments, the foaming temperature is 25-60°C, such as 25°C, 30°C, 33°C, 37°C, 40°C, 42°C, 45°C, 48°C, 50°C, 51°C, 55°C, 57°C, 59°C, etc.

[0022] In some preferred embodiments, the foaming time is 1 to 180 seconds, such as 1 second, 3 seconds, 5 seconds, 10 seconds, 15 seconds, 20 seconds, 30 seconds, 50 seconds, 60 seconds, 90 seconds, 120 seconds, 150 seconds, etc.; more preferably, the foaming time is 1 to 5 seconds.

[0023] In this invention, the inventors discovered that the foaming time has a significant impact on the morphology of the intermediate 1. Prolonged foaming time will cause the structure of the intermediate 1 to break down and disintegrate, making it impossible to prepare a micro-nano cavity thermal conductive film with a dense pore structure.

[0024] The intermediate 1 obtained after foaming is a wet graphene foam. The intermediate 1 is then carbonized and then graphitized.

[0025] In some preferred embodiments, the carbonization temperature is 900–1300°C, for example 900°C, 1000°C, 1080°C, 1100°C, 1150°C, 1200°C, 1250°C, etc.; preferably, the carbonization temperature is 1200–1300°C; more preferably, the carbonization temperature is 1200°C or 1300°C.

[0026] As a preferred embodiment, the carbonization temperature is 1200°C.

[0027] As a preferred embodiment, the carbonization temperature is 1300°C.

[0028] In some preferred embodiments, the graphitization temperature is 2000–3000°C, such as 2100°C, 2230°C, 2250°C, 2300°C, 2345°C, 2380°C, 2420°C, 2440°C, 2460°C, 2500°C, 2550°C, 2600°C, 2750°C, 2880°C, 2900°C, 2950°C, etc.; more preferably, the graphitization temperature is 2900°C–3000°C; more preferably, the graphitization temperature is 2900°C or 30000°C.

[0029] In some preferred embodiments, the areal density of the graphene micro / nano cavity thermal conductive film is 0.002 g / cm³. 2 ~0.2g / cm 2 Preferably, the areal density is 0.05 g / cm³. 2 ~0.2g / cm 2 ;

[0030] In some preferred embodiments, the porosity of the graphene micro / nano cavity thermal conductive film is 90-98%; in this invention, the porosity of the graphene micro / nano cavity thermal conductive film is related to the density of the thermal conductive film.

[0031] Porosity

[0032] The theoretical density of graphite is 2.0 g / cm³. 3 Or 2.1g / cm 3 .

[0033] In some preferred embodiments, the fabrication process of the graphene micro / nano cavity thermal conductive film is as follows:

[0034] A graphene oxide coating film with a carbon content of 60-70 wt% is placed in a reaction vessel, and a foaming composition, preferably hydrazine hydrate, is used for the reaction. The reaction temperature is 25-60°C, and the reaction time is 1-180 s, preferably 1-5 s. The reaction yields a wet graphene foam, which is intermediate 1. It is then dried in a drying oven. Afterward, it undergoes high-temperature carbonization at 900-1300°C, preferably 1200°C or 1300°C, and graphitization treatment at 2000-3000°C, preferably 2900°C or 3000°C, to obtain the final product.

[0035] In a second aspect, the present invention provides an application of a graphene micro / nano cavity thermal conductive film for use in pressure sensors, supercapacitors, fuel cells, carbon catalytic materials, switches, and optical modules.

[0036] A third aspect of the present invention provides a graphene micro / nano cavity phase change heat spreader, comprising the graphene micro / nano cavity thermal conductive film and a phase change material.

[0037] In some preferred embodiments, the graphene micro / nano cavity thermal conductive film has a wall thickness of 0.1–3.0 μm.

[0038] The wall thickness was obtained by scanning electron microscopy (SEM). The SEM machine was a JEOL JSM-7610F. The test conditions were to cut a sample cross-section and perform a low vacuum test with a magnification of 1000-2000 times.

[0039] In some preferred embodiments, the phase change material includes paraffin.

[0040] Beneficial effects: Compared with existing graphene micro / nano cavity thermal conductive films, the present invention has the following advantages:

[0041] 1. The X-ray diffraction pattern of the graphene micro / nano cavity thermal conductive film prepared by this invention satisfies 10°≤2θ. GFF -2θ GO≤20°; This indicates that the graphene micro-nano cavity thermal conductive film obtained by the method of the present invention has a regular structure and a perfect crystal structure, further demonstrating that the graphene micro-nano cavity thermal conductive film obtained by the present invention has excellent thermal conductivity and the planar thermal conductivity after compression of 80% can reach more than 300W / m·K.

[0042] 2. In the intermediate 1 formed by foaming the graphene micro-nano cavity thermal conductive film prepared by the present invention, the XPS spectrum satisfies: 20%≤AreaC-O / (AreaC-C+C=C)≤60%, which can achieve 80% of the compression rebound stress of the final thermal conductive film in the range of 0.01~0.2MPa.

[0043] 3. The areal density of the graphene micro / nano cavity thermally conductive film prepared by this invention is 0.002 g / cm³. 2 ~0.2g / cm 2 This ensures the application of thermal conductive films in pressure sensors, supercapacitors, fuel cells, carbon catalytic materials, switches, and optical modules;

[0044] 4. The graphene micro-nano cavity thermal conductive film obtained by this invention has a fluffy and porous microstructure and uniform and stable performance. It can also be used in combination with other materials in subsequent use, with a wide range of applications, great prospects, and diversified application fields. It is a rare high thermal and electrical conductivity material on the market. Attached Figure Description

[0045] Figure 1 The X-ray diffraction pattern of GO, the raw material for the graphene micro / nano cavity thermal conductive film prepared in Example 1 of this invention;

[0046] Figure 2 The X-ray diffraction pattern of the graphene micro / nano cavity thermal conductive film GFF prepared in Example 1 of this invention;

[0047] Figure 3 This is a 600x (×600) magnified SEM image of the graphene micro / nano cavity thermal conductive film prepared in Example 1 of the present invention.

[0048] Figure 4 This is a 2000x (×2000) magnified SEM image of the graphene micro / nano cavity thermal conductive film prepared in Example 1 of the present invention.

[0049] Figure 5 This is a 5000x (×5000) magnified SEM image of the graphene micro / nano cavity thermal conductive film prepared in Example 1 of the present invention.

[0050] Figure 6 The XPS spectrum of intermediate 1 in the preparation process of the graphene micro / nano cavity thermal conductive film in Example 1 of the present invention;

[0051] Figure 7The XPS spectrum of the graphene micro / nano cavity thermally conductive film GFF prepared in Example 1 of this invention is shown. Detailed Implementation

[0052] In this invention, X-ray diffraction was performed using a Rigaku Ultima IV instrument from Japan. The test conditions were as follows: a copper target was used as the test target, the scanning range was 5-90°, and the scanning speed was 10° / min.

[0053] XPS (X-ray photoelectron spectroscopy) was performed using an ESCAlab 250 XPS instrument, with the sample subjected to a base pressure of 3 × 10⁻⁶. -8 In the Pa energy analysis mode, X-rays of Al Kα 1486.8 eV were used as the excitation source to test the chemical composition of the sample;

[0054] The results were obtained by scanning electron microscopy (SEM). The SEM machine model was JEOL JSM-7610F. The test conditions were low vacuum testing with a cut sample cross-section and a magnification of 1000-5000 times.

[0055] Example

[0056] Example 1

[0057] A graphene micro / nano cavity thermal conductive film, wherein the thickness of the graphene thermal conductive film is tested using ASTM D374, and the thickness obtained by testing is 0.348 mm.

[0058] The X-ray diffraction pattern of the thermally conductive film satisfies: 2θ GFF -2θ GO =16.2°, XRD test results for GO and GFF are shown in [reference needed]. Figure 1 and Figure 2 ;

[0059] The peak area relationship of intermediate 1 in the XPS spectrum is as follows: AreaC-O / (AreaC-C+C=C)=43.74%, and the test results are shown in [reference needed]. Figure 6 and Figure 7 ;

[0060] The preparation process of the graphene micro / nano cavity thermal conductive film is as follows: A graphene oxide coating film with a carbon content of 66.51 wt% is placed in a reaction vessel and reacted with a foaming composition hydrazine hydrate, with a hydrazine hydrate mass concentration of 3%; the reaction temperature is 25℃ and the reaction time is 3s, resulting in a wet graphene foam, which is intermediate 1; subsequently, it is dried in a drying oven. Afterwards, it undergoes high-temperature carbonization at 1200℃ and graphitization at 2900℃ to obtain the final product.

[0061] Graphene oxide with a carbon content of 66.51 wt% was purchased from Yunnan Yuntian Morui Technology Co., Ltd.

[0062] The carbon content of the thermally conductive film obtained after graphitization is 1.489 times that of graphene oxide.

[0063] The planar thermal conductivity of the graphene micro / nano cavity thermal conductive film was tested using ASTM E1461-13, and the planar thermal conductivity after 80% compression was found to be 340.89 W / mK.

[0064] The test method for 80% resilience stress of graphene micro / nano cavity thermal conductive film is GB / T 8813, and the tested 80% resilience stress is 0.018 MPa.

[0065] The wall thickness of the graphene thermally conductive film was characterized by SEM, and the obtained wall thickness was 0.83 μm. (See details...) Figure 3 , Figure 4 and 5 .

[0066] The present invention also provides a micro-nano cavity thermal conductive film phase change heat spreader, comprising the graphene micro-nano cavity thermal conductive film prepared in Example 1 and a phase change material, wherein the phase change material is paraffin wax, the phase change peak temperature of paraffin wax is 45±2℃, and the enthalpy value is 210±10J / g.

[0067] The preparation method of the graphene micro-nano cavity phase change heat spreader includes the following steps: (1) placing the paraffin block in an 80°C vacuum drying oven and heating it to melt it into a liquid; (2) completely immersing the graphene micro-nano cavity thermal conductive film in the liquid paraffin and continuously wetting it for 10 minutes under a vacuum of -0.1MPa so that the paraffin liquid and the graphene micro-nano cavity thermal conductive film are completely composited; (3) taking out the filled graphene micro-nano cavity thermal conductive film and placing it vertically in an 80°C forced-air drying oven for at least 30 minutes to remove the residual paraffin liquid on the surface of the micro-nano cavity thermal conductive film; (4) placing the drained paraffin composite graphene micro-nano cavity thermal conductive film material at room temperature and cooling it for 10 minutes to obtain the graphene micro-nano cavity phase change heat spreader.

[0068] The obtained graphene micro / nano cavity phase change heat spreader has a phase change peak temperature of 43.7℃, an enthalpy of 158.06J / g, and a planar thermal conductivity of 68.79W / mK.

[0069] The graphene micro / nano cavity thermal conductive membrane provided by this invention is used in fuel cells.

[0070] Example 2

[0071] A graphene micro / nano cavity thermal conductive film, wherein the thickness of the graphene thermal conductive film is tested using ASTM D374, and the thickness obtained by testing is 0.447 mm.

[0072] The X-ray diffraction pattern of the thermal conductive film satisfies 2θ GFF -2θ GO =16.4°;

[0073] The peak areas of intermediate 1 in the XPS spectrum are as follows: AreaC-O / (AreaC-C+C=C)=35.42%;

[0074] The preparation process of the graphene micro / nano cavity thermal conductive film is as follows: A graphene oxide coating film with a carbon content of 66.51 wt% is placed in a reaction vessel and reacted with a foaming composition hydrazine hydrate, with a hydrazine hydrate mass concentration of 5%; the reaction temperature is 25℃ and the reaction time is 3s, resulting in a wet graphene foam, which is intermediate 1; subsequently, it is dried in a drying oven. Afterwards, it undergoes high-temperature carbonization at 1300℃ and graphitization at 2900℃ to obtain the final product.

[0075] Graphene oxide with a carbon content of 66.51 wt% was purchased from Yunnan Yuntian Morui Technology Co., Ltd.

[0076] The carbon content of the thermally conductive film obtained after graphitization is 1.498 times that of graphene oxide.

[0077] The test method for the planar thermal conductivity of graphene micro / nano cavity thermal conductive film is ASTM E1461-13. The planar thermal conductivity obtained after 80% compression is 352.71 W / mK.

[0078] The test method for 80% rebound stress of graphene micro / nano cavity thermal conductive film is GB / T 8813, and the tested 80% rebound stress is 0.015MPa.

[0079] The graphene micro-nano cavity thermally conductive film was characterized by SEM, and the wall thickness was found to be 0.71 μm.

[0080] The present invention also provides a micro / nano cavity thermal conductive film phase change heat spreader, comprising the graphene micro / nano cavity thermal conductive film prepared in Example 2 and a phase change material, wherein the phase change material is paraffin wax, the phase change peak temperature is 40±2℃, and the enthalpy value is 220±10J / g. The preparation method of the graphene micro-nano cavity phase change heat spreader includes the following steps: (1) placing the paraffin block in an 80°C vacuum drying oven and heating it to melt it into a liquid; (2) completely immersing the graphene micro-nano cavity thermal conductive film in the liquid paraffin and continuously wetting it for 10 minutes under a vacuum of -0.1MPa so that the paraffin liquid and the graphene micro-nano cavity thermal conductive film are completely composited; (3) taking out the filled graphene micro-nano cavity thermal conductive film and placing it vertically in an 80°C forced-air drying oven for at least 30 minutes to remove the residual paraffin liquid on the surface of the micro-nano cavity thermal conductive film; (4) placing the drained paraffin composite graphene micro-nano cavity thermal conductive film material at room temperature and cooling it for 10 minutes to obtain the graphene micro-nano cavity phase change heat spreader.

[0081] The obtained graphene micro-nano cavity phase change heat spreader has a phase change peak temperature of 39.06℃, an enthalpy of 173.81J / g, and a planar thermal conductivity of 59.17W / mK.

[0082] The graphene micro / nano cavity thermal conductive film provided by this invention can be used in carbon catalytic materials.

[0083] Example 3

[0084] A graphene micro / nano cavity thermal conductive film, wherein the thickness of the graphene thermal conductive film is tested using ASTM D374, and the thickness obtained by testing is 0.161 mm.

[0085] The X-ray diffraction pattern of the thermal conductive film satisfies 2θ GFF -2θ GO =17.1°;

[0086] The peak areas of intermediate 1 in the XPS spectrum are as follows: AreaC-O / (AreaC-C+C=C)=31.41%;

[0087] The preparation process of the graphene micro / nano cavity thermal conductive film is as follows: A graphene oxide coating film with a carbon content of 66.51 wt% is placed in a reaction vessel and reacted with a foaming composition hydrazine hydrate at a mass concentration of 1% at a reaction temperature of 25°C for 3 seconds. The reaction yields a wet graphene foam, which is intermediate 1; it is then dried in a drying oven. Afterwards, it undergoes high-temperature carbonization at 1200°C and graphitization at 3000°C to obtain the final product.

[0088] The carbon content of the thermally conductive film obtained after graphitization is 1.486 times that of graphene oxide.

[0089] The planar thermal conductivity of the graphene micro / nano cavity thermal conductive film was tested using ASTM E1461-13, and the planar thermal conductivity after 80% compression was found to be 313.23 W / mK.

[0090] The test method for 80% resilience stress of graphene micro / nano cavity thermal conductive film is GB / T 8813, and the tested 80% resilience stress is 0.01 MPa.

[0091] The graphene micro / nano cavity thermally conductive film was characterized by SEM, and the wall thickness was found to be 0.93 μm.

[0092] The present invention also provides a micro / nano cavity thermal conductive film phase change heat spreader, comprising the graphene micro / nano cavity thermal conductive film prepared in Example 3 and a phase change material, wherein the phase change material is paraffin, the phase change peak temperature is 40±2℃, and the enthalpy value is 220±10J / g.

[0093] The preparation method of the graphene micro-nano cavity phase change heat spreader includes the following steps: (1) placing the paraffin block in an 80°C vacuum drying oven and heating it to melt it into a liquid; (2) completely immersing the graphene micro-nano cavity thermal conductive film in the liquid paraffin and continuously wetting it for 10 minutes under a vacuum of -0.1MPa so that the paraffin liquid and the graphene micro-nano cavity thermal conductive film are completely composited; (3) taking out the filled graphene micro-nano cavity thermal conductive film and placing it vertically in an 80°C forced-air drying oven for at least 30 minutes to remove the residual paraffin liquid on the surface of the micro-nano cavity thermal conductive film; (4) placing the drained paraffin composite graphene micro-nano cavity thermal conductive film material at room temperature and cooling it for 10 minutes to obtain the graphene micro-nano cavity phase change heat spreader.

[0094] The obtained graphene micro-nano cavity phase change heat spreader has a phase change peak temperature of 39.14℃, an enthalpy of 184.89J / g, and a planar thermal conductivity of 82.21W / m·K.

[0095] The graphene micro / nano cavity thermal conductive film provided by this invention is used in optical modules.

[0096] Example 4

[0097] A graphene micro / nano cavity thermal conductive film, wherein the thickness of the graphene thermal conductive film is tested using ASTM D374, and the thickness obtained by testing is 1.561 mm.

[0098] The X-ray diffraction pattern of the thermal conductive film satisfies 2θ GFF -2θ GO =17.6°;

[0099] The peak area relationship of intermediate 1 in the XPS spectrum is as follows: AreaC-O / (AreaC-C+C=C)=36.6%;

[0100] The preparation process of the graphene micro / nano cavity thermal conductive film is as follows: A graphene oxide coating film with a carbon content of 66.51 wt% is placed in a reaction vessel and reacted with a foaming composition hydrazine hydrate, with a hydrazine hydrate mass concentration of 15%; the reaction temperature is 25℃ and the reaction time is 10s, resulting in a wet graphene foam, which is intermediate 1; subsequently, it is dried in a drying oven. Afterwards, it undergoes high-temperature carbonization at 1200℃ and graphitization at 2900℃ to obtain the final product.

[0101] Graphene oxide with a carbon content of 66.51 wt% was purchased from Yunnan Yuntian Morui Technology Co., Ltd.

[0102] The carbon content of the thermally conductive film obtained after graphitization is 1.664 times that of graphene oxide.

[0103] The planar thermal conductivity of the graphene micro / nano cavity thermal conductive film was tested using ASTM E1461-13, and the planar thermal conductivity after 80% compression was found to be 342.72 W / mK.

[0104] The test method for 80% resilience stress of graphene micro / nano cavity thermal conductive film is GB / T 8813, and the tested 80% resilience stress is 0.16 MPa.

[0105] The graphene micro / nano cavity thermally conductive film was characterized by SEM, and the wall thickness was found to be 1.12 μm.

[0106] The present invention also provides a micro / nano cavity thermal conductive film phase change heat spreader, comprising the graphene micro / nano cavity thermal conductive film prepared in Example 4 and a phase change material, wherein the phase change material is paraffin wax, the phase change peak temperature is 40±2℃, and the enthalpy value is 220±10J / g.

[0107] The preparation method of the graphene micro-nano cavity phase change heat spreader includes the following steps: (1) placing the paraffin block in an 80°C vacuum drying oven and heating it to melt it into a liquid; (2) completely immersing the graphene micro-nano cavity thermal conductive film in the liquid paraffin and continuously wetting it for 10 minutes under a vacuum of -0.1MPa so that the paraffin liquid and the graphene micro-nano cavity thermal conductive film are completely composited; (3) taking out the filled graphene micro-nano cavity thermal conductive film and placing it vertically in an 80°C forced-air drying oven for at least 30 minutes to remove the residual paraffin liquid on the surface of the micro-nano cavity thermal conductive film; (4) placing the drained paraffin composite graphene micro-nano cavity thermal conductive film material at room temperature and cooling it for 10 minutes to obtain the graphene micro-nano cavity phase change heat spreader.

[0108] The obtained graphene micro-nano cavity phase change heat spreader has a phase change peak temperature of 38.42℃, an enthalpy of 166.78J / g, and a planar thermal conductivity of 58.48W / m·K.

[0109] The graphene micro / nano cavity thermal conductive film provided by this invention can be used in carbon catalytic materials.

[0110] Example 5

[0111] A graphene micro / nano cavity thermal conductive film, wherein the thickness of the graphene thermal conductive film is tested using ASTM D374, and the thickness obtained by testing is 0.341 mm.

[0112] The X-ray diffraction pattern of the thermal conductive film satisfies 2θ GFF -2θ GO =15.7°;

[0113] The peak areas of intermediate 1 in the XPS spectrum are as follows: AreaC-O / (AreaC-C+C=C)=40.6%;

[0114] The preparation process of the graphene micro / nano cavity thermal conductive film is as follows: A graphene oxide coating film with a carbon content of 66.51 wt% is placed in a reaction vessel and reacted with a foaming composition sodium borate, with a sodium borate mass concentration of 3%; the reaction temperature is 25℃ and the reaction time is 3s, resulting in a wet graphene foam, which is intermediate 1; subsequently, it is dried in a drying oven. Afterwards, it undergoes high-temperature carbonization at 1200℃ and graphitization at 2900℃ to obtain the final product.

[0115] The carbon content of the thermally conductive film obtained after graphitization is 1.336 times that of graphene oxide.

[0116] The planar thermal conductivity of the graphene micro / nano cavity thermal conductive film was tested using ASTM E1461-13, and the planar thermal conductivity at 80% compression was found to be 336.45 W / mK.

[0117] The test method for 80% resilience stress of graphene micro / nano cavity thermal conductive film is GB / T 8813, and the tested 80% resilience stress is 0.13 MPa.

[0118] The graphene micro / nano cavity thermally conductive film was characterized by SEM, and the wall thickness was found to be 1.16 μm.

[0119] The present invention also provides a micro / nano cavity thermal conductive film phase change heat spreader, comprising the graphene micro / nano cavity thermal conductive film prepared in Example 5 and a phase change material, wherein the phase change material is paraffin wax, the phase change peak temperature is 40±2℃, and the enthalpy value is 220±10J / g.

[0120] The preparation method of the graphene micro-nano cavity phase change heat spreader includes the following steps: (1) placing the paraffin block in an 80°C vacuum drying oven and heating it to melt it into a liquid; (2) completely immersing the graphene micro-nano cavity thermal conductive film in the liquid paraffin and continuously wetting it for 10 minutes under a vacuum of -0.1MPa so that the paraffin liquid and the graphene micro-nano cavity thermal conductive film are completely composited; (3) taking out the filled graphene micro-nano cavity thermal conductive film and placing it vertically in an 80°C forced-air drying oven for at least 30 minutes to remove the residual paraffin liquid on the surface of the micro-nano cavity thermal conductive film; (4) placing the drained paraffin composite graphene micro-nano cavity thermal conductive film material at room temperature and cooling it for 10 minutes to obtain the graphene micro-nano cavity phase change heat spreader.

[0121] The obtained graphene micro-nano cavity phase change heat spreader has a phase change peak temperature of 39.12℃, an enthalpy of 176.78J / g, and a planar thermal conductivity of 28.18W / m·K.

[0122] Example 6

[0123] A certain company's HFC-GR series thermally conductive polyurethane foam, with a thickness of 0.5-5mm, has a thermal conductivity of only >1.0W / m·K after being compressed by 80%.

[0124] The process parameters and thermal conductive film parameters of the embodiments are shown in Tables 1 and 2.

[0125] Table 1:

[0126]

[0127] Table 2:

[0128]

[0129]

[0130] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A graphene micro / nano cavity thermal conductive film, characterized in that, It is obtained by coating graphene oxide into a film, reducing and foaming, carbonizing, and graphitizing. The thickness of the graphene micro / nano cavity thermal conductive film is 0.15~3mm; The X-ray diffraction pattern of the graphene micro / nano cavity thermal conductive film satisfies: 10° ≤ 2θ GFF -2θ GO ≤20°; 2θ GO The first diffraction angle of graphene oxide is 2θ; 2θ GFF The first diffraction angle of the micro / nano cavity thermal conductive film is 2θ. The fabrication process of the graphene micro / nano cavity thermal conductive film includes: A graphene oxide coating film with a carbon content of 60-70 wt% was placed in a reaction vessel and reacted using a foaming composition at a reaction temperature of 25-60℃ for 1-5 seconds to obtain a wet graphene foam, which is intermediate 1. The foam was then dried in a drying oven and subsequently subjected to high-temperature carbonization at 900-1300℃ and graphitization at 2000-3000℃ to obtain the graphene micro-nano cavity thermal conductive film. The foaming composition is selected from at least one of hydrazine hydrate, sodium borate, dimethylhydrazine, and thiourea; The relationship of the peak areas of intermediate 1 in the XPS spectrum is as follows: 20%≤AreaC-O / (AreaC-C+C=C)≤60%, where AreaC-O and AreaC-C+C=C are the peak areas of C1s carbon-oxygen single bonds and carbon-carbon single bonds and carbon-carbon double bonds in the XPS spectrum, respectively. The graphene micro / nano cavity thermal conductive film has a wall thickness of 0.1~3.0 μm; The graphene micro / nano cavity thermal conductive film has a compressive resilience stress of 0.01–0.23 MPa for 80% of its components.

2. The graphene micro / nano cavity thermal conductive film according to claim 1, characterized in that, The X-ray diffraction pattern of the graphene micro / nano cavity thermal conductive film satisfies: 12° ≤ 2θ GFF -2θ GO ≤17.5°, 2θ GO The first diffraction angle of graphene oxide is 2θ; 2θ GFF The first diffraction angle of the micro / nano cavity thermal conductive film is 2θ.

3. The graphene micro / nano cavity thermal conductive film according to claim 2, characterized in that, The mass concentration of the foaming composition is 0.05~80%.

4. The graphene micro / nano cavity thermal conductive film according to claim 3, characterized in that, The mass concentration of the foaming composition is 1-10%.

5. The graphene micro / nano cavity thermal conductive film according to claim 1, characterized in that, The carbon content of the graphene oxide is 60-70 wt%.

6. The graphene micro / nano cavity thermal conductive film according to claim 1 or 4, characterized in that, The carbon content of the graphene micro / nano cavity thermal conductive film obtained after graphitization is 1 to 2 times that of graphene oxide.

7. The graphene micro / nano cavity thermal conductive film according to claim 6, characterized in that, The carbon content of the graphene micro / nano cavity thermal conductive film obtained after graphitization is 1.2 to 1.7 times that of graphene oxide.

8. The application of a graphene micro / nano cavity thermal conductive film according to any one of claims 1 to 7 in pressure sensors, supercapacitors, fuel cells, carbon catalytic materials, switches, and optical modules.

9. A graphene micro / nano cavity phase change heat spreader, characterized in that, Includes the graphene micro / nano cavity thermal conductive film and phase change material as described in any one of claims 1 to 7.

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