Graphitization clamp, graphene film and preparation method of graphene film
By applying controllable tension to the graphene carbonization film using a graphitization fixture during the graphitization process, combined with the homogenization and foaming process of graphene oxide slurry, the problem of graphene sheet orientation damage was solved, achieving high orientation and high thermal diffusivity of the graphene film, making it suitable for heat dissipation materials in high-end electronic devices.
Patent Information
- Application Number
- CN202511906623.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-17
- Publication Date
- 2026-02-24
AI Technical Summary
In the traditional redox method for preparing graphene films, the orientation of graphene sheets is damaged, which limits the improvement of thermal conductivity. In particular, sheet collapse and gas rupture during high-temperature graphitization lead to the destruction of orientation.
A graphitization fixture is used to apply controllable tension to the graphene carbonization film. The film is kept under tension during the high-temperature graphitization process by a film suspension mechanism and a tensioning mechanism. Combined with the homogenization treatment and foaming process of graphene oxide slurry, the high orientation of the sheets along the stretching direction is ensured.
It significantly improves the orientation degree and in-plane thermal diffusivity of graphene films, meeting the heat dissipation material requirements of high-end electronic devices. The fixture structure is simple and reliable, and it is suitable for ultra-high temperature environments.
Smart Images
Figure CN121557734A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of graphene preparation technology, specifically to a fixture for graphitizing graphene films, a graphene film, and a method for preparing the same. Background Technology
[0002] Graphene films have broad application prospects in the field of heat dissipation for electronic devices due to their excellent in-plane thermal conductivity. The core indicator of their thermal conductivity—the thermal diffusivity—is closely related to the orientation degree of the graphene sheets. The higher the orientation degree, the smaller the resistance to heat flow in the in-plane direction, and the higher the thermal diffusivity.
[0003] Currently, the preparation of graphene films using the redox method typically involves steps such as graphene oxide slurry coating, film formation, carbonization, and high-temperature graphitization. The orientation of graphene sheets is a multi-stage process: during the coating and drying of the graphene oxide slurry, the graphene sheets will, to some extent, align along the coating direction, forming an initial orientation structure; in subsequent pretreatment and carbonization processes, the physical and chemical structure of the film material is solidified, and the initial orientation is preserved; during graphitization, the internal layers of the carbonized graphene film undergo lattice repair, growth, and rearrangement, determining the final crystal integrity and orientational order.
[0004] However, in the traditional redox method for preparing graphene films, the film material is usually laid flat for each process. Its own gravity can cause some sheets to collapse or sag. At the same time, during the thermal reduction process, the release of gas that breaks through the horizontally oriented sheets can also destroy the original orientation. All of these will destroy the orientation structure formed in the previous process, thus limiting the further improvement of the thermal conductivity of the graphene film. Summary of the Invention
[0005] Based on the technical problems mentioned in the background art, one objective of this application is to provide a graphitization fixture that can apply a controllable tension to the graphene carbon film during the graphitization process, so that the graphene carbon film is kept in a taut state, thereby guiding the graphene sheets to be highly oriented along the stretching direction. Another objective of this application is to provide a method for preparing a graphene film using the above-mentioned graphitization fixture, which improves the orientation and thermal diffusivity of the graphene film through the synergy of the process and the fixture. A third objective of this invention is to provide a graphene film with high orientation and high thermal diffusivity prepared by the above method.
[0006] To achieve the above objectives, the present invention adopts the following technical solution: Firstly, a graphitized fixture is provided, comprising: A membrane suspension mechanism is used to fix and suspend one end of the graphene carbonized membrane. A membrane tensioning mechanism is connected to the other end of the graphene carbonized film and applies tension to the graphene carbonized film so that the graphene carbonized film remains taut throughout the high-temperature graphitization process.
[0007] In a preferred embodiment, the membrane suspension mechanism includes a first clamping part for holding the graphene carbon film and a support frame for supporting the first clamping part; the membrane tensioning mechanism includes a second clamping part for holding the graphene carbon film and a counterweight fixedly connected to the second clamping part. The graphene carbon film is continuously and stably tensioned by the weight of the counterweight or by applying tension to the graphene carbon film through the counterweight.
[0008] The first clamping part and the second clamping part mentioned in the embodiments of this application only need to achieve the tight clamping of the graphene carbonization film, and their specific structure is not limited.
[0009] In a preferred embodiment, the first clamping part and / or the second clamping part includes a pressure bar, which is connected to the support frame or counterweight by one or more bolts. This structure provides secure clamping and facilitates loading and unloading.
[0010] In a preferred embodiment, the membrane suspension mechanism is provided with a threaded hole, and the membrane tensioning mechanism is provided with a limiting hole relative to the threaded hole of the membrane suspension mechanism. A threaded rod passes through the threaded hole and the limiting hole to connect the membrane suspension mechanism and the membrane tensioning mechanism. Through the cooperation of the threaded rod, the threaded hole, and the limiting hole, it can be ensured that the tension applied to the membrane is always transmitted in a preset direction, avoiding lateral deviation, thereby ensuring the accuracy and consistency of the tension direction.
[0011] As a preferred embodiment, the graphitization fixture provided in the first aspect of this application is made of pure graphite material to ensure that it does not soften, deform, or react with graphene film material in ultra-high temperature environments above 2800°C.
[0012] Secondly, the present invention provides a method for preparing a graphene film, comprising the following steps: S1. Mix the graphene oxide cake with ammonia and aqueous solution, homogenize and defoam, and prepare a graphene oxide slurry with a solid content of 3-8% and a viscosity of 1000-7000cp. S2. Coat the graphene oxide slurry into a graphene oxide film; S3. Pretreatment and carbonization of graphene oxide film to prepare graphene carbonized film. S4. The graphene carbonization film is held in place using the graphitization fixture provided in the first aspect of this application, so that the graphene carbonization film is graphitized in a stretched state, wherein the stretching direction of the graphene carbonization film is consistent with the initial coating direction of the graphene oxide slurry. S5. The graphitized film material is calendered to obtain the target graphene film.
[0013] The above steps work together to align the graphene sheets inside the graphene film.
[0014] First, during the coating and drying process of graphene oxide slurry, the graphene oxide sheets will be oriented to a certain extent along the coating direction, forming an initial orientation structure. The solid content directly determines the effective concentration of graphene oxide sheets in the slurry. If the solid content is too low (e.g., <3%), the number of functional sheets per unit volume will be small, resulting in a thin and sparse film after drying. The interaction forces between the sheets will be weak, leading to insufficient strength and stability of the initial orientation structure, making it easily damaged during subsequent high-temperature processing. If the solid content is too high (e.g., >8%), the slurry will be too viscous, resulting in poor fluidity. During coating, it will be difficult to fully spread and orient a large number of sheets through shear force, and it will easily lead to uneven coating thickness, causing sheet distortion or disordered stacking, which will also damage the consistency of the initial orientation. Viscosity is the core factor of the leveling ability of graphene oxide slurry. If the viscosity is too low, the slurry leveling is too good, and it may flow before the graphene oxide film dries due to excessive fluidity, damaging the initial orientation structure. If the viscosity is too high, there will also be a problem of high shear resistance, resulting in disordered initial stacking of sheets.
[0015] Preferably, the solid content and viscosity of the graphene oxide sheets can be controlled by controlling the homogenization process. The homogenization is performed ≥2 times, and the homogenization pressure is 700~1300 bar. The primary purpose of the first high-pressure homogenization treatment is to exfoliate the graphene oxide sheets, preferably to exfoliate the graphene oxide sheets into single layers or few layers. The purpose of the second homogenization is to further exfoliate large-diameter graphene oxide sheets into smaller-diameter sheets, thereby promoting the full expansion of the graphene oxide sheets in the slurry, resulting in a more ordered liquid crystal arrangement and improving the orientation in the subsequent film formation process.
[0016] In subsequent pretreatment and carbonization processes, the initial orientation of the film material is preserved. During graphitization, the internal layers of the graphene carbonized film undergo lattice repair, growth, and rearrangement, determining the final crystal integrity and orientation order. However, the applicant discovered that graphene oxide films shrink and bend during heat treatment, which to some extent affects the orientation consistency of the graphene sheets. Furthermore, graphene oxide films and graphene pretreatment retain a large number of oxygen-containing functional groups, making them brittle and hard, unsuitable for stretching and orientation. In contrast, the functional groups in the graphene carbonized film are largely removed, resulting in a more flexible film material with weaker interlayer van der Waals forces, leading to better stretching and orientation. Therefore, during graphitization, the graphene carbonized film is stretched in its coating direction to limit the shrinkage and bending of the sheets. Stretching allows the sheets to spread, further improving the orientation degree of the film sheets and thus enhancing the planar thermal conductivity.
[0017] In a preferred embodiment, after step S2, a step S22 is further included: immersing the graphene oxide film in a foaming agent with a concentration of 10%~30% for foaming, with a foaming time of 1~180s, preferably 1~60s; the foaming agent includes one or more of hydrazine hydrate, sodium borohydride, dimethylhydrazine, and thiourea. The purpose of this step is to controllably create pores in the graphene oxide film, thereby giving the prepared graphene film an internal cavity structure similar to a sponge, thus enabling the graphene film to have compression resilience.
[0018] In a preferred embodiment, in step S4, the graphene carbonization film bears a load of 0.05-0.25 kg / cm in the tensile direction, based on the film width. This load range provides optimal orientation guiding force without tearing the film. If the tensile force is less than 0.05 kg / cm, stretching cannot positively improve the thermal diffusion of the graphene film; if the tensile force is greater than 0.25 kg / cm, the film is prone to breakage during graphitization.
[0019] In a preferred embodiment, the maximum temperature of the pretreatment is 170~360℃, the maximum temperature of the carbonization treatment is 1100~1400℃, and the maximum temperature of the graphitization treatment is 2800~3100℃.
[0020] Thirdly, the present invention provides a graphene film prepared by any of the above-described preparation methods. Because the graphene film undergoes directional stretching during the critical graphitization stage, its graphene sheets exhibit extremely high orientation, thus demonstrating excellent planar thermal conductivity.
[0021] The beneficial effects of this application are as follows: 1. The graphitization fixture provided by this invention has a simple and reliable structure. By applying a continuous and controllable tensile force to the film material during the ultra-high temperature graphitization process, the graphene sheets are arranged in a highly ordered manner along the stretching direction during the lattice growth and recombination process, which fundamentally improves the orientation of the film.
[0022] 2. By ensuring that the stretching direction is consistent with the initial coating direction, the orientation structure of the graphene film is synergistically strengthened through multiple steps, which greatly improves the limit of thermal conductivity.
[0023] 3. The fixture can be made of high-temperature resistant graphite material to adapt to extreme environments; by adjusting the counterweight, it can meet different process precision and force requirements; the method steps are clear, the parameter range is optimized, and it is easy to promote and apply in existing production lines.
[0024] 4. The graphene film prepared by this method and fixture has extremely high graphene sheet orientation and a significantly improved in-plane thermal diffusivity compared to similar products that do not use the stretching graphitization process, which can meet the stringent requirements of high-end electronic devices for heat dissipation materials with ultra-high thermal conductivity. Attached Figure Description
[0025] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0026] Figure 1 This is a structural diagram of a graphitized fixture provided in Embodiment 1 of this application. Figure 2 This is a cross-sectional SEM image of the graphene film in Example 2. Figure 3 This is a horizontal thermal diffusion test diagram of the graphene film in Example 2. Figure 4 This is a cross-sectional SEM image of the graphene film in Example 3. Figure 5 This is a horizontal thermal diffusion test diagram of the graphene film in Example 3. Figure 6 Horizontal thermal diffusion test diagram of graphene film in Comparative Example 1 Figure 7 Horizontal thermal diffusion test diagram of graphene film in Comparative Example 2 Figure 8 Horizontal thermal diffusion test diagram of graphene film in Comparative Example 3 1-Membrane suspension mechanism; 111-Pressure strip; 112-Bolt fasteners; 12-Support frame; 2. Membrane tensioning mechanism; 211-Pressure strip; 212-Bolt fastener; 22-Counterweight; 3. Threaded rod Detailed Implementation
[0027] The following detailed description of exemplary embodiments of this application refers to the accompanying drawings, which form part of the description and illustrate exemplary embodiments in which this application may be implemented. The more detailed description of embodiments of this application below is not intended to limit the scope of the claimed application, but is merely illustrative and does not limit the description of the features and characteristics of this application, in order to suggest the best mode for carrying out this application and sufficient to enable those skilled in the art to implement it. However, it should be understood that various modifications and variations can be made without departing from the scope of this application as defined by the appended claims. The detailed description and drawings should be considered illustrative only and not restrictive, and any such modifications and variations shall fall within the scope of this application described herein. Furthermore, the background art is intended to illustrate the current state of research and development and significance of the technology, and is not intended to limit this application or its application areas.
[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0029] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.
[0030] The detection methods involved in this application are as follows: Density: Calculated according to density = mass / volume, where mass is weighed using an analytical balance.
[0031] SEM: The results were obtained using a scanning electron microscope (SEM). The SEM machine model was JEOL JSM-7610F. The test conditions were to cut a sample cross-section and perform a low-vacuum test.
[0032] Thermal diffusivity: The test method described in the standard "Q / GDMR 04-2023 Thermal diffusivity test by laser flare method".
[0033] Example 1 This embodiment provides a graphitized clamp that uses a threaded rod to adjust the tension. The clamp is entirely made of high-purity graphite.
[0034] The graphitization fixture includes a membrane suspension mechanism 1 and a membrane tensioning mechanism 2.
[0035] The membrane suspension mechanism 1 includes a support frame 12 and two graphite pressure strips 111 serving as the first clamping part. Multiple threaded holes are provided on the crossbeam of the support frame 12. Each pressure strip 111 is locked to the crossbeam of the support frame 12 by two bolt fasteners 112, thereby firmly clamping one end of the graphene carbonized film between the pressure strip 111 and the crossbeam of the support frame 12.
[0036] The membrane tensioning mechanism 2 includes two graphite pressure strips 211 serving as the second clamping part and a counterweight block 22 fixedly connected to the second clamping part. The structure and clamping method of the pressure strips 211 are the same as those of the membrane suspension mechanism 1.
[0037] The membrane suspension mechanism and the membrane tensioning mechanism are limited by the threaded rod 3. The limiting hole on the membrane suspension mechanism is a threaded hole, which fixes the relative position of the membrane suspension mechanism and the threaded rod. The limiting hole on the membrane tensioning mechanism is not threaded, which is to ensure that the tension applied to the membrane is always transmitted in the preset direction and avoids lateral deviation.
[0038] The tension provided by the counterweight 22 to the graphene carbonized film is adjusted by the gravity of the counterweight so that the tension applied to the film per unit width falls within the range of 0.05-0.25 kg / cm.
[0039] In use, first clamp and suspend the upper end of the graphene carbonized film using the film suspension mechanism 1. Then let it hang freely, and clamp its lower end using the film tensioning mechanism 2. At this time, adjust the tension of the counterweight 22 on the film to keep the film straight and taut in the vertical direction. Subsequently, place the entire fixture along with the taut film into a high-temperature graphitization furnace for processing.
[0040] Example 2 This embodiment provides a method for preparing a graphene film: S1. A graphene oxide cake with an oxygen content of 43.21% was mixed with ammonia and an aqueous solution, homogenized, and defoamed to prepare a graphene oxide slurry with a solid content of 5.14% and a viscosity of 3513 cp. Homogenization was performed twice, with the first homogenization pressure at 700 bar and the second at 750 bar. S2. Using a coating rate of 0.8 m / min, the graphene oxide slurry is coated into a 3 mm thick graphene oxide wet film, and after drying, a graphene oxide film is obtained. S3. The graphene oxide film is pretreated and carbonized to prepare a graphene carbonized film. The highest temperature for pretreatment is 320℃, and the holding time at the highest temperature is 3h. The highest temperature for carbonization is 1200℃, and the holding time at the highest temperature is 1h. S4. The graphene carbonized film is held in place using the graphitization fixture provided in Example 1 of this application, and graphitization is performed on the graphene carbonized film under tension. The tension on the film is controlled to be 0.20 kg / cm. The stretching direction of the graphene carbonized film is consistent with the initial coating direction of the graphene oxide slurry. The graphitization temperature is 3100℃, and the graphitization time at this temperature is 1 hour. S5. The graphitized film was subjected to plate pressing at a pressure of 210 kg / cm², resulting in a graphene film with a density of 2.18 g / cm³. Its SEM image is shown below. Figure 2 As shown in the figure, the test results of the thermal diffusivity are as follows. Figure 3 As shown, it is 885 mm² / s.
[0041] Example 3 This embodiment provides a method for preparing a graphene film: S1. A graphene oxide cake with an oxygen content of 40.87% was mixed with ammonia and an aqueous solution, homogenized, and defoamed to prepare a graphene oxide slurry with a solid content of 4.95% and a viscosity of 3219 cp. Homogenization was performed twice, with the first homogenization pressure at 700 bar and the second at 750 bar. S2. Using a coating rate of 0.8 m / min, the graphene oxide slurry is coated into a 3 mm thick graphene oxide wet film, and after drying, a graphene oxide film is obtained. S22. The graphene oxide film is immersed in a 30% hydrazine hydrate solution for foaming for 3 seconds. Then the graphene oxide film is taken out of the foaming agent solution and dried at 50°C.
[0042] S3. The graphene oxide film is pretreated and carbonized to prepare a graphene carbonized film. The highest temperature for pretreatment is 270℃, and the holding time at the highest temperature is 3h. The highest temperature for carbonization is 1200℃, and the holding time at the highest temperature is 1h. S4. The graphene carbonized film is held in place using the graphitization fixture provided in Example 1 of this application, and graphitization is performed on the graphene carbonized film under tension. The tension on the film is controlled to be 0.23 kg / cm. The stretching direction of the graphene carbonized film is consistent with the initial coating direction of the graphene oxide slurry. The graphitization temperature is 3100℃, and the graphitization time at this temperature is 1 hour. S5. The graphitized film was rolled under a pressure of 2.0 MPa to obtain a graphene film with a density of 0.16 g / cm³. Its SEM image is shown below. Figure 4 As shown in the figure, the test results of the thermal diffusivity are as follows. Figure 5 As shown, it is 834 mm² / s.
[0043] Compared with the graphene obtained in Example 2, the graphene in Example 3 has micro-nano pores, which gives the graphene film compression resilience and makes it more suitable for use as a thermal interface material.
[0044] It is worth noting that in step S22 of this embodiment, hydrazine hydrate was used as the foaming agent. In other embodiments, one or more of sodium borohydride, dimethylhydrazine, and thiourea may also be used. In step S22 of this embodiment, a 30% concentration foaming agent is used for foaming for 3 seconds. In other embodiments, a 10% concentration foaming agent can be used for foaming for 60 seconds, or a 20% concentration foaming agent can be used for foaming for 10 seconds. The specific foaming time and foaming agent concentration can be adjusted adaptively according to factors such as ambient temperature, and no limiting provisions are made here.
[0045] Examples 4-5 The difference between this embodiment and Embodiment 2 is that, in step S1, the viscosity of the graphene oxide slurry is controlled by changing the pressure of the first and second homogenization processes; all other steps remain the same as in Embodiment 2. The homogenization parameters changed in step S1 and the performance parameters of the resulting graphene film are shown in the table below: Example Group First homogeneous pressure (bar) Second homogeneous pressure (bar) Viscosity (cp) of graphene oxide slurry Graphene film density (g / cm³) Thermal diffusivity of graphene film (mm² / s) Example 2 700 750 3213 2.18 885 Example 4 800 850 2734 2.18 920 Example 5 900 1100 2271 2.15 941 At a suitable viscosity, the graphene oxide film is coated by shear force, which allows a large number of sheets to fully expand and align in a directional manner. Then, with the synergistic orientation graphitization, the resulting graphene film has a good horizontal thermal diffusivity, which is ≥800mm² / s.
[0046] Examples 6-7 The difference between this embodiment and Embodiment 2 is that, in step S1, the solid content of the graphene oxide slurry is changed; all other steps remain the same as in Embodiment 2. The solid content parameters changed in step S1 and the performance parameters of the resulting graphene film are shown in the table below: Example Group Solid content of graphene oxide slurry Graphene film density (g / cm³) Thermal diffusivity of graphene film (mm² / s) Example 2 5% 2.18 885 Example 6 3% 2.12 870 Example 7 8% 2.20 891 With a suitable solid content, the graphene oxide film obtained after drying the graphene oxide slurry has a moderate thickness and strong connection between the layers, resulting in high strength and stability of the initial orientation structure. The obtained graphene films all have good horizontal thermal diffusivity, all ≥800mm² / s. Examples 8-9
[0047] The difference between this embodiment and Embodiment 2 is that in step S4, the tensile force on the graphene carbonization film is controlled and changed by adjusting the gravity of the counterweight. All other steps remain the same as in Embodiment 2. The tensile force changed in step S4 and the performance parameters of the resulting graphene film are shown in the table below: Example Group Tensile force during graphitization (kg / cm) Graphene film density (g / cm³) Thermal diffusivity of graphene film (mm² / s) Example 2 0.20 2.18 885 Example 8 0.24 2.14 939 Example 9 0.12 2.11 828 During the graphitization process, the graphene carbon film is stretched in its coating direction to restrict the shrinkage and bending of the sheets during graphitization. The stretching causes the sheets to spread out. Under the premise that the coating step has a preliminary orientation, the orientation degree of the film sheets is further improved. As a result, the graphene films obtained all have good horizontal thermal diffusivity, which is ≥800mm² / s. Comparative Example 1
[0048] The steps of this comparative example are basically the same as those of Example 2, except that in step S4, the graphitization fixture provided in Example 1 of this application is not used. Instead, the graphene carbonization film is laid flat on a graphite plate and then the same graphitization and calendering processes are performed.
[0049] The graphene film prepared in this manner has a density of 2.08 g / cm³. The thermal diffusivity was tested, and the results are as follows: Figure 6 As shown, it is 718 mm² / s.
[0050] The thermal diffusivity data from Comparative Example 1 and Example 2 show that stretching the graphene carbon film in its coating direction during the graphitization process can improve the orientation of the graphene film layers, thereby improving the horizontal thermal conductivity of the graphene film. Comparative Example 2
[0051] The steps of this comparative example are basically the same as those of Example 2, except that in step S1, the solid content of the prepared graphene oxide slurry is 10%.
[0052] The graphene film prepared in this manner has a density of 2.12 g / cm³. The thermal diffusivity was tested, and the results are as follows: Figure 7 As shown, it is 731 mm² / s.
[0053] The thermal diffusivity data from Comparative Example 2 and Example 2 show that graphene oxide slurry with high solid content is not conducive to the initial orientation alignment of graphene oxide sheets during the coating stage, which in turn reduces the horizontal thermal conductivity. Comparative Example 3
[0054] The steps of this comparative example are basically the same as those of Example 2, except that in step S1, the graphene oxide slurry is homogenized only once, which results in a higher viscosity of the graphene oxide slurry, which is 8812 cp.
[0055] The graphene film prepared in this manner has a density of 1.95 g / cm³. The thermal diffusivity was tested, and the results are as follows: Figure 8 As shown, it is 726 mm² / s.
[0056] The thermal diffusivity data from Comparative Example 3 and Example 2 show that high-viscosity graphene oxide slurry is not conducive to the initial orientation of graphene oxide sheets during the coating stage. Its shear resistance is large, resulting in disordered initial stacking of sheets and a decrease in horizontal thermal conductivity.
[0057] It should be noted that the proportions of raw materials and the preparation process not mentioned above can be referred to existing technologies, and will not be elaborated here.
[0058] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.
[0059] Although this application has been illustrated and described with reference to certain preferred embodiments thereof, those skilled in the art should understand that various changes in form and detail may be made thereto without departing from the spirit and scope of this application.
Claims
1. A graphitized fixture, characterized in that, include: A membrane suspension mechanism is used to fix and suspend one end of the graphene carbonized membrane. A membrane tensioning mechanism is connected to the other end of the graphene carbonized film and applies tension to the graphene carbonized film to keep the graphene carbonized film in a taut state.
2. The graphitization fixture according to claim 1, characterized in that, The membrane suspension mechanism includes a first clamping part for clamping the graphene carbonized membrane and a support frame for supporting the first clamping part; the membrane tensioning mechanism includes a second clamping part for clamping the graphene carbonized membrane and a counterweight block fixedly connected to the second clamping part.
3. The graphitization fixture according to claim 2, characterized in that, The first clamping part and / or the second clamping part includes a pressure bar, which is connected to the support frame or counterweight by one or more bolt fasteners.
4. The graphitization fixture according to claim 1, characterized in that, The membrane suspension mechanism is provided with a threaded hole, and the membrane tensioning mechanism is provided with a limiting hole relative to the position of the threaded hole of the membrane suspension mechanism. The threaded rod passes through the threaded hole and the limiting hole to connect the membrane suspension mechanism and the membrane tensioning mechanism.
5. The graphitization fixture according to claim 1, characterized in that, The graphitization fixture is made of graphite.
6. A method for preparing a graphene film, characterized in that, Includes the following steps: S1. Mix the graphene oxide cake with ammonia and aqueous solution, homogenize and defoam, and prepare a graphene oxide slurry with a solid content of 3-8% and a viscosity of 1000-7000cp. S2. The graphene oxide slurry is coated into a graphene oxide film. S3. The graphene oxide film is pretreated and carbonized to prepare a graphene carbonized film. S4. The graphene carbonization film is held in a graphitization fixture according to any one of claims 1-5, and the graphene carbonization film is kept in a stretched state for graphitization treatment. The stretching direction of the graphene carbonization film is consistent with the coating direction of the graphene oxide slurry. S5. The graphitized film material is calendered to obtain the target graphene film.
7. The method for preparing a graphene film according to claim 6, characterized in that, The method also includes step S22, immersing the graphene oxide film in a foaming agent for foaming. The foaming agent includes one or more of hydrazine hydrate, sodium borate, dimethylhydrazine, and thiourea. The concentration of the foaming agent is 10% to 30%, and the foaming time is 1 to 180 seconds. Preferably, the foaming time is 1 to 60 seconds.
8. The method for preparing a graphene film according to claim 6, characterized in that, The tensile load of the graphene carbonized film is 0.05-0.25 kg / cm.
9. The method for preparing a graphene film according to claim 6, characterized in that, The maximum temperature for the pretreatment is 170~360℃, the maximum temperature for the carbonization treatment is 1100~1400℃, and the maximum temperature for the graphitization treatment is 2800~3100℃.
10. A graphene film, characterized in that, The graphene film is obtained according to any one of claims 6-9.