Graphene workpiece with electric heating performance and preparation method

Abstract

The invention provides a graphene workpiece with electric heating performance and a preparation method, and the method comprises the following steps: carrying out laser irradiation treatment on the surface of a diamond matrix, and forming a high-orientation graphite layer on the surface of the diamond matrix; the outer layer of the high-orientation graphite layer is subjected to mechanical cleavage treatment, a graphene layer formed by a plurality of graphene sheets is obtained, and the angle between the graphene sheets in the graphene layer and the surface of the diamond matrix is 30-40 degrees; the graphene layer is subjected to electrochemical stripping, the pH value of electrolyte adopted for electrochemical stripping is 9, the angle between a graphene sheet in the graphene layer and the surface of the diamond substrate is 80-90 degrees, the micro-nano-scale nearly-vertical graphene layer is formed, and the graphene workpiece with the electric heating performance is obtained. The invention further provides a workpiece manufactured by the method. Compared with the prior art, electric heating graphene can be directly generated on the surface of the diamond in situ, complex process steps such as reduction are omitted, the service life is far longer than that of a common graphene film electric heating element, and the electric heating performance is excellent.

Description

Technical Field

[0001] The present invention belongs to the field of surface engineering technology, and in particular to the field of graphene electric heating technology, and specifically to a graphene product with electric heating performance and a preparation method thereof. Background Art

[0002] Graphene is a single-atom-layer two-dimensional carbon nanomaterial. 2 Hybrid connection is the thinnest and strongest material currently available. It also has a huge specific surface area and excellent thermal properties. Its thermal conductivity is between 4840 and 5300 W / (m·K), making it the carbon material with the highest thermal conductivity currently available.

[0003] However, graphene still faces many unavoidable key issues in its widespread application. For example, most common graphene preparations use graphene oxide as raw material. In order to obtain graphene with better electrical and thermal conductivity, extremely complex processes need to be adopted to reduce it so that the carbon atom structure can be restored. In addition, the graphene film obtained by coating graphene on an insulating substrate has weak adhesion to the substrate and a short lifespan. It is difficult to find an ideal substrate for graphene, and the thermal conductivity between graphene and silicon or metal interfaces is often limited. Therefore, it is difficult to prepare graphene products with good electrothermal properties.

[0004] Based on the above, the present invention proposes a graphene component with electrothermal performance and a preparation method to solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to provide a graphene product with electrothermal performance and a preparation method thereof in view of the deficiencies in the prior art. The method adopts a method of in-situ generating electrothermal graphene on the surface of diamond. Compared with the traditional graphene preparation method, complex process steps such as reduction are omitted, and the service life of the obtained product far exceeds that of ordinary graphene film electrothermal elements.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0007] (I) The present invention provides a method for preparing a graphene product with electrothermal performance, comprising the following steps: subjecting a surface of a diamond substrate to laser irradiation treatment to form a highly oriented graphite layer on the surface of the diamond substrate; subjecting an outer layer of the highly oriented graphite layer to mechanical cleavage treatment to obtain a graphene layer formed of a plurality of graphene sheets, wherein the angle between the graphene sheets in the graphene layer and the surface of the diamond substrate is 30 to 40°; subjecting the graphene layer to electrochemical stripping, wherein the pH of the electrolyte used in the electrochemical stripping is 8 to 10, so that the angle between the graphene sheets in the graphene layer and the surface of the diamond substrate is 80 to 90°, thereby forming a micro-nano-scale nearly vertical graphene layer, thereby obtaining a graphene product with electrothermal performance.

[0008] Furthermore, the equipment used for the laser irradiation treatment is a pulsed laser; the laser irradiation operation is carried out in an air atmosphere, the pulse frequency is 30kHz, the spot diameter is 20μm, the laser power is 8-10W, and the scanning spacing is 1μm; based on the heat dissipation of the diamond substrate during the laser irradiation treatment, the angle between the laser incident direction of the pulsed laser and the surface to be processed of the diamond substrate is 80-85°. With the precision of the laser, the present invention can ensure the accuracy of the electrothermal graphene generation area, and can generate electrothermal graphene in a fixed shape and position. The present invention preferably performs laser irradiation treatment under the above conditions to obtain a layered graphite layer of suitable thickness.

[0009] Furthermore, the equipment used for the mechanical cleavage includes a flywheel made of stainless steel, with an outer diameter of 120 mm and a thickness of 8 mm. During the mechanical cleavage process, the flywheel feed control accuracy is 1 μm and the flywheel speed is 2000 r / min.

[0010] Furthermore, in the electrochemical stripping operation, the electrolyte is a mixed solution of (NH4)2SO4 and NaOH, and the pH of the electrolyte is 9.

[0011] Furthermore, the electrochemical stripping operation is carried out in a classic two-part immersion electrode system, specifically: a graphene piece with an angle of 30 to 40° with the surface of the diamond substrate is used as a working anode, and a platinum sheet is used as a working cathode for electrochemical stripping. The applied voltage during stripping is 10V and the stripping time is 30 minutes.

[0012] Furthermore, the size of the platinum sheet is 10×15×0.1 mm 3 , purity>99.9%; the positive and negative poles are placed in parallel with a distance of 3cm.

[0013] Furthermore, the diamond substrate is a diamond coated component or a diamond thick film component, wherein the diamond coated component is prepared by depositing a diamond coating on the substrate by a CVD deposition method.

[0014] Furthermore, after the laser irradiation treatment, the thickness of the highly oriented graphite layer formed is 100 to 300 nm; the thickness of the micro-nano scale nearly vertical graphene layer with high-efficiency electrothermal performance obtained after the electrochemical stripping is 700 to 900 nm.

[0015] (ii) The present invention also provides a graphene component with electrothermal properties, which is prepared by the method described above, and the graphene component includes a diamond substrate connected by carbon-carbon covalent bonds, a highly oriented graphite layer and a graphene layer with high-efficiency electrothermal properties, and the angle between the graphene sheets of the graphene layer and the surface of the diamond substrate is 80 to 90°.

[0016] Furthermore, in the graphene product, the mass fraction of graphene with high-efficiency electrothermal performance is 50-70%, the mass fraction of highly oriented graphite layers is 20-30%, and the mass fraction of amorphous carbon is 10%.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The present invention forms a highly oriented graphite layer on the surface of a diamond substrate by laser irradiation treatment, and mechanically cleaves the graphite layer to obtain a graphene layer, wherein the angle between the graphene sheets in the graphene layer and the surface of the diamond substrate is 30 to 40°, and finally, electrochemical stripping is performed to change the angle between the graphene sheets in the graphene layer and the surface of the diamond substrate from 30 to 40° to 80 to 90°, and the nearly vertical graphene sheets overlap each other to form a good conductive grid, thereby obtaining a more excellent electrothermal performance;

[0019] (2) Compared with the conventional graphene with electrothermal properties prepared by deposition method, the method provided by the present invention can directly generate electrothermal graphene in situ on the diamond surface, which not only omits the complex process steps such as reduction, but also has a lifespan far exceeding that of ordinary graphene film electrothermal elements, and has better electrothermal performance than ordinary graphene electrothermal elements;

[0020] (3) With the help of the precision of laser, the present invention can ensure the accuracy of the electrothermal graphene generation area, and can generate electrothermal graphene in a fixed shape and position, with high flexibility, low operating difficulty and strong applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The scanning electron microscope images of the electrothermal graphene product prepared in Example 1 at different magnifications are shown in FIG. Figure 1 a is a scanning electron microscope image of the electrothermal graphene product at a magnification of 15,000. Figure 1 b is a scanning electron microscope image of the electrothermal graphene product at a magnification of 20,000. Figure 1 c is a scanning electron microscope image of the electrothermal graphene product at a magnification of 35,000;

[0022] Figure 2 This is a scanning electron microscope image of the workpiece in Example 1 after mechanical cleavage and chemical stripping treatment, wherein: Figure 2 a is an electron microscope image of the graphene layer after mechanical cleavage treatment in step 2 of Example 1, Figure 2 b is an electron microscope image of the graphene layer after electrochemical stripping in step 3 of Example 1;

[0023] Figure 3 A two-part immersed electrode system for use in electrochemical stripping;

[0024] Figure 4The temperature rise curve of the electrothermal graphene product prepared in Example 1 under different heat flux densities;

[0025] Figure 5 The temperature rise curves of the graphene prepared in Example 1 and Comparative Examples 1-2 under the same heat flux density. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] The present invention provides a method for preparing a graphene product with electrothermal performance, comprising the following steps:

[0028] The surface of the diamond substrate is treated with laser irradiation to form a highly oriented graphite layer on the surface of the diamond substrate, thereby obtaining a graphite layer-containing product. The outer layer of the highly oriented graphite layer is treated with mechanical cleavage to obtain a graphene layer formed by multiple graphene sheets, and the angle between the graphene sheets in the graphene layer and the surface of the diamond substrate is 30 to 40 degrees. The graphene layer is subjected to electrochemical stripping, and the pH of the electrolyte used in the electrochemical stripping is 8 to 10, so that the angle between the graphene sheets in the graphene layer and the surface of the diamond substrate is 80 to 90 degrees, forming a micro-nano-scale nearly vertical graphene layer, that is, a graphene product with electrothermal properties is obtained.

[0029] For the diamond substrate, natural diamond or artificial diamond can be selected, and diamond coating parts, diamond thick film parts or CVD diamond are more preferred. The present invention does not limit the type, shape and size of diamond, and can be selected according to needs. Before laser irradiation treatment, the diamond substrate needs to be flattened, cleaned and dried to facilitate uniform absorption of laser. Flattening, cleaning and drying methods belong to conventional technical means in this field, and the present invention does not limit this.

[0030] For laser irradiation operation, the equipment used for laser irradiation treatment is a pulsed laser, and the preferred operating parameters of the embodiment of the present invention are: pulse frequency of 30kHz, spot diameter of 20μm, laser power of 8-10W, and scanning spacing of 1μm. Through laser irradiation treatment, the diamond on the surface of the diamond substrate will phase change into graphite to form a graphite layer of a certain thickness. With the help of the precision of the laser, the present invention can ensure the accuracy of the electrothermal graphene generation area, and can generate electrothermal graphene in a fixed shape and positioning. In addition, based on the consideration of heat dissipation of the diamond substrate during laser irradiation treatment, the angle between the laser incident direction of the pulsed laser and the surface to be processed of the diamond substrate is 80-85°.

[0031] After obtaining the graphite layer-containing article, the present invention performs mechanical cleavage on the graphite layer-containing article, so that the outer layer of the graphite layer is cleaved into a graphene layer formed by a plurality of graphene sheets, and the angle between the graphene sheets in the graphene layer and the surface of the diamond substrate is 30-40 degrees. The equipment used for mechanical cleavage includes a flywheel made of stainless steel, with an outer diameter of 120 mm and a thickness of 8 mm; the operating conditions of the mechanical cleavage include: a flywheel feed control accuracy of 1 μm and a flywheel speed of 2000 r / min.

[0032] After obtaining the graphene layer product, the present invention performs electrochemical stripping on the graphene layer product. The electrochemical stripping is carried out in a classic two-part immersion electrode system, with the graphene layer product as the working anode and a platinum sheet (purity>99.9%) as the working cathode for stripping. The positive and negative electrodes are placed in parallel, the electrolyte is a mixed solution of (NH4)2SO4 and NaOH, the pH value is 8 to 10, preferably the pH value is 9, the voltage applied during stripping is 10V, and the duration is 30 minutes.

[0033] Compared with the traditional graphene with electrothermal properties prepared by deposition method, the present invention generates Wiener-scale nearly vertical graphene layers in situ on the diamond surface. The graphene is evenly distributed on the diamond surface, and the graphene sheets overlap each other to form a good conductive grid, thereby obtaining excellent electrothermal performance, omitting complex process steps such as reduction, and the electrothermal performance is better than that of ordinary graphene electrothermal elements.

[0034] Example 1

[0035] The embodiment of the present invention provides a graphene product with electrothermal performance, and the preparation method thereof comprises the following steps:

[0036] Step 1: Take a CVD diamond sheet with a size of 10mm×10mm×0.4mm, grind, wash with acetone and dry, and then use a laser (pulsed laser, IPG Photonics, model YLP-1 / 100 / 20) to irradiate the surface of the CVD diamond sheet in an air atmosphere. Considering the heat dissipation of the diamond substrate during the laser irradiation process, the angle between the laser incident direction of the laser and the surface to be processed of the diamond substrate is 85°. After laser irradiation, a highly oriented graphite layer is formed on the surface of the CVD diamond sheet (fluffy graphite can be observed through the CCD lens). When the laser irradiation process is performed, specifically, full-surface laser filling scanning is performed starting from the edge of the CVD diamond sheet. The operating parameters include: a pulse frequency of 30kHz, a spot diameter of 20μm, a laser power of 8W, a scanning spacing of 1μm, and a thickness of the highly oriented graphite layer finally obtained of 100nm.

[0037] Step 2: Use a flywheel to mechanically cleave the outer layer of the highly oriented graphite layer prepared in step 1, wherein the flywheel is a stainless steel flywheel with a brushed and polished surface, and the outer surface of the stainless steel flywheel is flat, the outer diameter of the stainless steel flywheel is 120 mm, and the thickness is 8 mm. The operating conditions of the mechanical cleavage include: the flywheel feed control accuracy is 1 μm, and the flywheel speed is 2000 r / min. After the mechanical cleavage is completed, a graphene layer (layer thickness is 700 nm) formed by multiple graphene sheets is obtained, and the angle between the graphene sheet and the surface of the diamond substrate in the graphene layer is 30-40°.

[0038] Step 3: Use the classic two-part immersion electrode system to electrochemically strip the graphene layer prepared in step 2. Specifically, use the graphene product with an angle of 30-40° to the surface of the diamond substrate as the working anode, and the platinum sheet as the working cathode. The positive and negative electrodes are placed in parallel with a spacing of 3 cm. The electrochemical stripping is performed. The applied voltage during stripping is 10V and the stripping time is 30 minutes. The size of the platinum sheet is 10×15×0.1mm 3 , purity>99.9%. In the electrochemical stripping operation, the electrolyte is a mixed solution of (NH4)2SO4, NaOH and water, wherein the pH of the electrolyte is 9.

[0039] After electrochemical stripping, the angle between the graphene sheets in the graphene layer and the surface of the diamond substrate is 80 to 90 degrees, forming a nearly vertical graphene layer at a micro-nano scale, and thus obtaining a graphene product with electrothermal properties.

[0040] The graphene product with electrothermal performance prepared in this embodiment includes a diamond matrix connected by carbon-carbon covalent bonds, a highly oriented graphite layer and a graphene layer with high-efficiency electrothermal performance, and the angle between the graphene sheet of the graphene layer and the surface of the diamond matrix is ​​80-90°. Among them, the mass fraction of graphene with high-efficiency electrothermal performance is 70%, the mass fraction of the highly oriented graphite layer is 20%, and the mass fraction of amorphous carbon is 10%.

[0041] Example 2

[0042] A graphene product with electrothermal properties was prepared according to the method of Example 1, except that during the laser irradiation treatment, the laser power was 9W.

[0043] In this embodiment, after laser irradiation treatment is performed on the surface of the CVD diamond sheet, the thickness of the highly oriented graphite layer obtained is 100nm. After mechanical cleavage treatment and electrochemical stripping, the thickness of the micro-nano scale nearly vertical graphene layer formed is 800nm. In the graphene product with electrothermal performance finally obtained, the mass fraction of graphene is 60%, the mass fraction of the highly oriented graphite layer is 25%, and the mass fraction of amorphous carbon is 15%.

[0044] Example 3

[0045] A graphene product with electrothermal properties was prepared according to the method of Example 1, except that during the laser irradiation treatment, the laser power was 10 W.

[0046] In this embodiment, after laser irradiation treatment is performed on the surface of the CVD diamond sheet, the thickness of the highly oriented graphite layer obtained is 300nm. After mechanical cleavage treatment and electrochemical stripping, the thickness of the micro-nano scale nearly vertical graphene layer formed is 900nm. In the graphene product with electrothermal performance finally obtained, the mass fraction of graphene is 50%, the mass fraction of the highly oriented graphite layer is 30%, and the mass fraction of amorphous carbon is 20%.

[0047] Comparative Example 1

[0048] The diamond-graphene component prepared in Example 1 of the invention patent with application number 202011472104.4 comprises diamond and a graphene film generated in situ on the surface of the diamond.

[0049] Comparative Example 2

[0050] The diamond product with a mixed-dimensional carbon covalent stacking structure surface layer prepared in Example 1 of the invention patent with application number 2022103707517 comprises a diamond substrate and a mixed-dimensional carbon covalent stacking structure surface layer; the mixed-dimensional carbon covalent stacking structure surface layer comprises, from the inside to the outside, micro-nanoscale near-vertical graphite layers and graphene layers connected by carbon-carbon covalent bonds. The angle between the graphene sheet in the micro-nanoscale near-vertical graphite layer and the surface of the diamond substrate is 70-80°, the graphene layer is formed by multiple graphene sheets, the angle between the graphene sheet in the graphene layer and the surface of the diamond substrate is independently 0-90°, and the angle between the graphene sheet in the graphene layer and the surface of the diamond substrate is not 0° at the same time.

[0051] Characterization and performance testing:

[0052] Figure 1 The scanning electron microscope images of the electrothermal graphene product prepared in Example 1 at different magnifications are shown, wherein: Figure 1 a is a scanning electron microscope image of the electrothermal graphene product at a magnification of 15,000. Figure 1 b is a scanning electron microscope image of the electrothermal graphene product at a magnification of 20,000. Figure 1 c is a scanning electron microscope image of the electrothermal graphene component at a magnification of 35,000.

[0053] Figure 2 a is an electron microscope image of the graphene layer after mechanical cleavage treatment in step 2 of Example 1, Figure 2 b is an electron microscope image of the graphene layer after electrochemical stripping in step 3 of Example 1.

[0054] The two ends of the electrothermal graphene product prepared in Example 1 were bonded with copper foil electrodes using conductive silver paste, and different heat flux densities (0.3 w / cm 2 、0.6w / cm 2 and 0.9w / cm 2 ),like Figure 4 As shown in the figure, as the heat flux density increases, the heating rate and the maximum steady-state temperature of the electrothermal graphene component also increase.

[0055] The two ends of the electrothermal graphene products prepared in Example 1 and Comparative Examples 1-2 were bonded with copper foil electrodes using conductive silver paste, and the same heat flux density was applied to both ends to test the heating rate and the highest steady-state temperature of Example 1 and Comparative Examples 1-2. The test results are shown in Figure 5 ,Depend on Figure 5 It can be seen that compared with comparative examples 1 to 2, the electrothermal graphene product prepared in the present invention has higher electrothermal conversion efficiency and stronger electrothermal performance.

[0056] The above are only preferred implementations of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a graphene product with electrothermal performance, characterized in that: The following steps are involved: The surface of the diamond substrate is subjected to laser irradiation treatment to form a highly oriented graphite layer on the surface of the diamond substrate; The outer layer of the highly oriented graphite layer is subjected to mechanical cleavage treatment to obtain a graphene layer formed by a plurality of graphene sheets, wherein the angle between the graphene sheets and the surface of the diamond substrate in the graphene layer is 30-40°; The graphene layer is subjected to electrochemical stripping, and the pH value of the electrolyte used in the electrochemical stripping is 8-10, so that the angle between the graphene sheets in the graphene layer and the surface of the diamond substrate is 80-90 degrees, forming a micro-nano-scale nearly vertical graphene layer, and obtaining a graphene product with electrothermal properties.

2. The method for preparing a graphene product with electrothermal performance according to claim 1, characterized in that: The equipment used for the laser irradiation treatment is a pulsed laser; During the laser irradiation operation, the pulse frequency is 30 kHz, the spot diameter is 20 μm, the laser power is 8-10 W, and the scanning interval is 1 μm; the angle between the laser incident direction of the pulse laser and the surface of the diamond substrate is 80-85°.

3. The method for preparing a graphene product with electrothermal performance according to claim 1, characterized in that: The equipment used for the mechanical cleavage includes a flywheel, the outer diameter of the flywheel is 120 mm and the thickness is 8 mm; During the mechanical cleavage process, the flywheel feed control accuracy is 1 μm and the flywheel speed is 2000 r / min.

4. The method for preparing a graphene product with electrothermal performance according to claim 1, characterized in that: In the electrochemical stripping operation, the electrolyte is a mixed solution of (NH4)2SO4 and NaOH, and the pH of the electrolyte is 9.

5. The method for preparing a graphene product with electrothermal performance according to claim 1, characterized in that: The electrochemical stripping operation is specifically as follows: The graphene product with an angle of 30 to 40° with the surface of the diamond substrate was used as the working anode, and the platinum sheet was used as the working cathode for electrochemical stripping. The applied voltage during stripping was 10 V and the stripping time was 30 minutes.

6. The method for preparing a graphene product with electrothermal performance according to claim 5, characterized in that: The platinum sheet has a size of 10×15×0.1 mm 3 , purity>99.9%; the positive and negative poles are placed in parallel with a distance of 3cm.

7. The method for preparing a graphene product with electrothermal performance according to claim 1, characterized in that: The diamond substrate is a diamond coating component or a diamond thick film component.

8. The method for preparing a graphene product with electrothermal performance according to claim 1, characterized in that: After the laser irradiation treatment, the thickness of the formed highly oriented graphite layer is 100 to 300 nm; The thickness of the micro-nano scale nearly vertical graphene layer obtained after the electrochemical stripping is 700-900nm.

9. A graphene product with electrothermal properties, prepared by the method according to any one of claims 1 to 8, characterized in that: The graphene product comprises a diamond matrix, a high-orientation graphite layer and a graphene layer connected by carbon-carbon covalent bonds, and the angle between the graphene sheets of the graphene layer and the surface of the diamond matrix is ​​80-90 degrees.

10. The graphene article with electrothermal performance according to claim 9, characterized in that: In the graphene product, the mass fraction of graphene is 50-70%, the mass fraction of highly oriented graphite layer is 20-30%, and the mass fraction of amorphous carbon is 10%.

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