Graphene fiber electric heating assembly and preparation method and application thereof

Abstract

The invention relates to the technical field of electric heating, and discloses a graphene fiber electric heating assembly and a preparation method and application thereof.The graphene fiber electric heating assembly comprises a base body, an electric heating functional layer conformally wrapping the surface of the base body and a resistance regulation and control layer conformally wrapping the surface of the electric heating functional layer; the matrix is a fiber or a product thereof, the electric heating function layer is a graphene film, and the resistance regulation and control layer is a graphene oxide film; the base body provides mechanical properties required by the electric heating assembly; the graphene film is an electric heating functional layer and provides a conductive path; the graphene oxide film is a resistance regulation and control layer, the resistance of the electric heating device can be regulated and controlled according to different oxidation degrees of the graphene film, and the heating uniformity of the electric heating device is not changed; when a device with a special-shaped structure, such as a trapezoid, an arc, a polygon and other irregular shapes, is involved, the local graphene oxide resistance is changed, so that uniform heating of the whole device is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric heating, in particular to a graphene fiber electric heating assembly and a preparation method and application thereof. BACKGROUND

[0002] A graphene coating layer with controllable thickness is directly grown on the surface of traditional glass fiber to obtain a uniform and continuous graphene glass fiber composite material, which has good electric heating performance, can be heated from room temperature to 300 DEG C in less than 10 s, and has a high electric heating conversion efficiency of up to 87%, which is much higher than that of conventional electric heating materials, and has the advantages of light weight and flexibility which are not possessed by conventional electric heating materials. At present, the graphene glass fiber material has achieved great success in the field of aircraft ice prevention and removal, and shows unique and irreplaceable advantages.

[0003] Chinese patent document CN108545966A discloses a preparation method of graphene glass fiber. The graphene layer is formed on the surface of the glass fiber by chemical vapor deposition, so that the graphene glass fiber has excellent comprehensive performance, wide application range, and the preparation method of the graphene glass fiber is simple and has good industrial application prospect. However, the carbon source content and heating temperature are fixed during each production, and the sheet resistance value of the generated graphene glass fiber fabric is single, so it is difficult to control the sheet resistance of the material in subsequent actual application.

[0004] In addition, in actual application, there are scenes involving special-shaped structures, such as trapezoidal, arc-shaped, polygonal and irregular shapes. Since the positive and negative electrode spacing of the special-shaped structure cannot be kept consistent, the current preferentially flows from the positive electrode to the negative electrode along the shortest path, which can cause uneven heating of the overall graphene glass fiber electric heating device.

[0005] Therefore, it is necessary to develop a graphene fiber electric heating assembly which can control the resistance of graphene glass fiber fabric by a simple and effective method. In addition, for special-shaped graphene glass fiber electric heating devices, how to make the overall surface of the sample evenly heat without changing the electrode structure is a problem to be solved in the field. SUMMARY

[0006] Therefore, the present application provides a graphene fiber electric heating assembly to solve the problems of graphene fiber resistance control and uneven heating of the overall surface of special-shaped graphene fiber electric heating devices in the prior art.

[0007] The present application also provides a preparation method of the graphene fiber electric heating assembly.

[0008] In a first aspect, the present application provides a graphene fiber electric heating assembly, which comprises a substrate, an electric heating functional layer conformally coated on the surface of the substrate, and a resistance control layer conformally coated on the surface of the electric heating functional layer. The base is a fiber or a product thereof, the electric heating functional layer is a graphene film, and the resistance regulating layer is an oxidized graphene film.

[0009] In some alternative embodiments, the base comprises short fibers or a fiber blanket processed therefrom, or continuous long fibers or a fiber fabric woven therefrom.

[0010] In some alternative embodiments, the fibers comprise quartz fibers, glass fibers, alumina fibers, ceramic fibers, silicon carbide fibers, or boron fibers.

[0011] In some alternative embodiments, the sheet resistance of the graphene fiber electric heating assembly is 100 Ω·sq -1 - 5000 Ω·sq -1 .

[0012] In some alternative embodiments, the thickness of the electric heating functional layer is 50 nm-100 nm.

[0013] In some alternative embodiments, the thickness of the resistance regulating layer is 5 nm-10 nm.

[0014] In a second aspect, the present application provides a preparation method of the graphene fiber electric heating assembly of the first aspect, comprising the following steps: (1) introducing a carbon source gas to deposit and grow a graphene film on the surface of the base to obtain a graphene fiber fabric; (2) oxidizing the graphene fiber fabric at 200℃-400℃ to form an oxidized graphene film, thereby obtaining the graphene fiber electric heating assembly.

[0015] In some alternative embodiments, the oxidation method comprises: oxidizing the graphene fiber fabric in a muffle furnace or a heating table in an air atmosphere; or, oxidizing the graphene fiber fabric in a tube furnace in an oxygen atmosphere.

[0016] In some alternative embodiments, the oxidation time is 1 h-5 h.

[0017] In some alternative embodiments, the deposition step comprises: increasing the temperature to 900℃-1100℃ at a temperature increasing rate of 10℃ / min-20℃ / min, and maintaining the pressure at 10 Pa-100 Pa for 1 h-3 h.

[0018] In a third aspect, the present application provides an electric heating device comprising the graphene fiber electric heating assembly of the first aspect or the graphene fiber electric heating assembly prepared by the preparation method of the second aspect, and electrodes located on both sides of the graphene fiber electric heating assembly.

[0019] Compared with the prior art, the technical scheme of the present application has the following advantages: 1. The graphene fiber electrothermal assembly provided by the present application comprises a substrate, an electrothermal functional layer conformally coated on the surface of the substrate, and a resistance control layer conformally coated on the surface of the electrothermal functional layer; the substrate is a fiber or a product thereof, the electrothermal functional layer is a graphene film, and the resistance control layer is an oxidized graphene film; the substrate provides the mechanical properties required by the electrothermal assembly; the graphene film serves as the electrothermal functional layer and provides an electrically conductive path; the oxidized graphene film serves as the resistance control layer and can control the resistance of the electrothermal device according to the different oxidation degrees of the graphene film without changing the uniformity of heat generation; when irregularly shaped devices such as trapezoidal, arc-shaped, polygonal, etc. are involved, the local oxidized graphene resistance can be changed to achieve uniform overall heating of the device.

[0020] 2. The preparation method of the graphene fiber electrothermal assembly provided by the present application comprises the following steps: introducing a carbon source gas to deposit and grow a graphene layer on the surface of the substrate to obtain a graphene fiber fabric; and oxidizing the graphene fiber fabric at 200-400 DEG C to form an oxidized graphene layer and obtain a graphene fiber electrothermal assembly. The present application uses chemical vapor deposition to deposit and grow a graphene layer on the surface of the substrate, and then performs oxidation treatment at 200-400 DEG C to control the resistance of the graphene fiber without changing the uniformity of heat generation; for devices with irregular shapes, a heating platform can be used for local heating to selectively oxidize part of the area and control the local resistance, thereby achieving uniform overall heating of the device and widening the application of graphene fiber fabric in the field of irregularly shaped electrothermal devices. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the description of the specific embodiments or the prior art. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0022] Figure 1 is a circuit analysis diagram of graphene glass fiber fabric (a) and graphene fiber electrothermal assembly (b) of the embodiment of the present application; Figure 2 is a schematic diagram of the Raman spectrum of graphene glass fiber fabric (a) and graphene fiber electrothermal assembly (b) prepared in Example 7 of the present application; Figure 3 is the peak intensity ratio of Raman D peak and G peak of graphene glass fiber fabric and graphene fiber electrothermal assembly prepared in Example 7 of the present application; Figure 4 is a schematic diagram of the change rate of the polar resistance of the graphene fiber electrothermal component prepared at different oxidation temperatures according to an embodiment of the present application; Figure 5 is a photo of the graphene fiber electrothermal component prepared in Comparative Example 2 of the present application; Figure 6-a is a scanning electron microscope image of the graphene glass fiber fabric prepared in Example 5 of the present application; wherein, (a-1) is at a magnification of 100; (a-2) is at a magnification of 800; (a-3) is at a magnification of 8000; and (a-4) is at a magnification of 20000; Figure 6-b is a scanning electron microscope image of the graphene fiber electrothermal component prepared in Example 5 of the present application; wherein, (b-1) is at a magnification of 100; (b-2) is at a magnification of 800; (b-3) is at a magnification of 8000; and (b-4) is at a magnification of 20000; Figure 6-c is a scanning electron microscope image of the graphene fiber electrothermal component prepared in Example 7 of the present application; wherein, (c-1) is at a magnification of 100; (c-2) is at a magnification of 800; (c-3) is at a magnification of 8000; and (c-4) is at a magnification of 20000; Figure 7-a is an infrared radiation image of the graphene glass fiber fabric prepared in Example 7 of the present application; Figure 7-b is an infrared radiation image of the graphene fiber electrothermal component prepared in Example 7 of the present application; Figure 8 is the temperature of the 9 temperature measuring points of the graphene glass fiber fabric and the graphene fiber electrothermal component prepared in Example 7 of the present application in the infrared radiation test. DETAILED DESCRIPTION

[0023] The following examples are provided to better further understand the present application, and are not limited to the best mode, and do not constitute a limitation on the content and protection scope of the present application. Any person under the inspiration of the present application or the combination of the present application with other prior art features, any product same or similar to the present application, falls within the protection scope of the present application.

[0024] The specific experimental steps or conditions not mentioned in the examples can be performed according to the conventional experimental steps described in the literature in the art or the operation or conditions. The reagents or instruments not mentioned by the manufacturer are all conventional reagent products that can be obtained by market purchase.

[0025] In order to solve the problems existing in the above related technologies, according to a first aspect of the present application, the present application provides a graphene fiber electrothermal assembly, which comprises a substrate, an electrothermal functional layer conformally coated on the surface of the substrate, and a resistance control layer conformally coated on the surface of the electrothermal functional layer; the substrate is a fiber or a product thereof, the electrothermal functional layer is a graphene film, and the resistance control layer is an oxidized graphene film; the square resistance of the graphene fiber electrothermal assembly is 100 Ω·sq -1 -5000 Ω·sq -1 ; the thickness of the electrothermal functional layer is 50 nm-100 nm; the thickness of the resistance control layer is 5 nm-10 nm; the substrate comprises chopped fibers or a fiber blanket processed therefrom, or continuous long fibers or a fiber fabric woven therefrom; the fibers comprise quartz fibers, glass fibers, alumina fibers, ceramic fibers, silicon carbide fibers, or boron fibers.

[0026] In a second aspect, the present application provides a preparation method of a graphene fiber electrothermal assembly, which comprises the following steps: (1) removing the surface glue layer of the substrate by high-temperature oxidation: placing the fiber fabric substrate in a reaction chamber, introducing oxygen into the reaction chamber, increasing the temperature to 400℃-500℃ at a temperature increasing rate of 10℃ / min-20℃ / min, and taking it out after holding for 1h-4h; (2) depositing graphene on the surface of the substrate: introducing hydrogen, a carbon source gas, and a protective gas into the reaction chamber of the tube furnace, the carbon source gas comprising at least one of methane, ethylene, propylene, acetylene, and propyne, and the protective gas comprising at least one of nitrogen and argon, increasing the temperature to 900℃-1100℃ at a temperature increasing rate of 10℃ / min-20℃ / min, ensuring that the pressure in the reaction chamber is 10 Pa-100 Pa, and depositing for 1h-3h to obtain a graphene fiber fabric; (3) graphene oxidation treatment: comprising method one, method two, or method three, which are as follows: Method one: taking the graphene fiber fabric out of the tube furnace, placing it in a muffle furnace, heating the muffle furnace to 200℃-400℃, and heating for 1h-5h; Method two: after the graphene deposition is completed, reducing the temperature of the tube furnace to 200℃-400℃, introducing oxygen, and heating for 1h-5h; Method three: taking the graphene fiber fabric out of the tube furnace, placing it on a heating table, heating the heating table to 200℃-400℃, and heating for 1h-5h.

[0027] The graphene layer is deposited on the surface of the substrate by chemical vapor deposition, and then oxidation treatment is carried out at 200-400 DEG C, so that the resistance of the graphene glass fiber is regulated, and the uniformity of heating is not changed; for the special-shaped structure device, the local resistance can be regulated according to the resistance change rule of the graphene fiber under different temperature oxidation to realize uniform heating, and the application of the graphene fiber fabric in the special-shaped electric heating device field is widened.

[0028] Taking the glass fiber as the substrate, electrodes are added on both sides of the graphene glass fiber fabric, and after power-on, a complex circuit is formed in the material, as shown in Figure 1 , two fibers in parallel contact, the circuit is equivalent to two resistances in parallel (R 0-1 and R 0-2 represent the resistances of two different graphene glass fibers) and the contact resistance R c1 of the two fibers in series; a plurality of parallel graphene glass fibers form a warp bundle, the resistance is R warp , and the weft is perpendicular to the warp bundle, the resistance is R weft , R warp and R weft are connected in parallel, and the contact resistance R c2 of the warp and weft bundles is connected in series; since the graphene glass fiber can be commercially produced, we often get samples with given resistance, and the resistance of the graphene glass fiber cannot be regulated by a simple and effective method; in addition, in the actual application, the scene involving special-shaped structure, such as trapezoidal, arc, polygon and irregular shape, only the resistance can be changed locally, the overall heating of the sample surface can be ensured.

[0029] After the oxidation treatment on the surface of the sample with known resistance, the outer surface of the graphene coated on the outer layer of the glass fiber becomes graphene oxide, and the resistivity of the graphene oxide is much higher than that of the graphene, and according to the different oxidation degrees of the graphene, the resistance can be regulated within a certain range. The surface of the graphene glass fiber is oxidized, the resistance R0 is increased, the contact resistance R c1 is increased, and the resistances R warp and R weft of the warp and weft bundles and the contact resistance R c2 are also increased compared with the unoxidized graphene glass fiber, so that the resistance regulation design can be carried out according to the actual demand, and the application of the graphene glass fiber in the electric heating field is widened.

[0030] The application will be further described in detail in combination with specific embodiments, and these embodiments cannot be understood as limiting the scope of the application.

[0031] Example 1 The embodiment provides a preparation method of a graphene fiber electric heating assembly, comprising the following steps: The glass fiber is placed in the reaction chamber for pretreatment, and is raised to 500℃ at a rate of 10℃ / min under an atmosphere of 200sccm oxygen at normal pressure, and is taken out after holding for 4h; the pretreated glass fiber is placed in the reaction chamber of a CVD tube furnace, vacuum is drawn to keep the pressure at 10Pa, and is raised to 1050℃ at a rate of 10℃ / min under an atmosphere of 100sccm argon, 25sccm hydrogen and 100sccm methane, the reaction time is 1h, and the graphene glass fiber fabric is taken out after cooling.

[0032] Example 2 The present example provides a preparation method of a graphene fiber electrothermal assembly, which is basically the same as the steps of Example 1, and the only difference is that the oxidation temperature is 300℃.

[0033] Example 3 The present example provides a preparation method of a graphene fiber electrothermal assembly, which is basically the same as the steps of Example 1, and the only difference is that the oxidation temperature is 320℃.

[0034] Example 4 The present example provides a preparation method of a graphene fiber electrothermal assembly, which is basically the same as the steps of Example 1, and the only difference is that the oxidation temperature is 340℃.

[0035] Example 5 The present example provides a preparation method of a graphene fiber electrothermal assembly, which is basically the same as the steps of Example 1, and the only difference is that the oxidation temperature is 360℃.

[0036] Example 6 The present example provides a preparation method of a graphene fiber electrothermal assembly, which is basically the same as the steps of Example 1, and the only difference is that the oxidation temperature is 380℃.

[0037] Example 7 The present example provides a preparation method of a graphene fiber electrothermal assembly, which is basically the same as the steps of Example 1, and the only difference is that the oxidation temperature is 400℃.

[0038] Comparative Example 1 The present comparative example provides a preparation method of a graphene fiber electrothermal assembly, which is basically the same as the steps of Example 1, and the only difference is that the oxidation temperature is 150℃.

[0039] Comparative Example 2 The present comparative example provides a preparation method of a graphene fiber electrothermal assembly, which is basically the same as the steps of Example 1, and the only difference is that the oxidation temperature is 420℃.

[0040] Experimental Example 1 Raman test was performed on the graphene glass fiber fabric and graphene fiber electrothermal assembly prepared in Example 7, and the results are shown in Figure 2 As can be seen from the figure, the Raman spectrum of graphene is composed of several peaks, mainly G peak and D peak; D peak is the disordered vibration peak of graphene, and the specific peak position of the peak is 1328.4 cm -1 , which is used to characterize the structural defects or edges in the graphene sample; G peak is the main characteristic peak of graphene, which is caused by the in-plane vibration of sp2 carbon atoms, and appears near 1580 cm -1 , which can effectively reflect the number of layers of graphene, but is easily affected by stress; in order to explore the change of defects of graphene fiber electrothermal assembly, the peak intensity ratio of D peak and G peak is shown in Figure 3 As can be seen from the figure, after oxidation at 400℃, the intensity of D peak is usually enhanced, and the intensity ratio (I D / I G ) of D peak and G peak increases, indicating that graphene oxide is generated on the surface after oxidation.

[0041] Experimental Example 2 The two sides of the graphene glass fiber fabric and graphene fiber electrothermal assembly prepared in each example were respectively made into power supply electrodes by using copper tape, and copper sheets were welded at the end of the power supply electrodes as lead-out electrodes. After power-on, the resistance between the two electrodes was tested by using a multimeter, and the results are shown in Figure 4 and Table 1; wherein, the change rate of electrode resistance%= (resistance of graphene fiber electrothermal assembly-resistance of graphene glass fiber fabric) / resistance of graphene glass fiber fabric x 100%.

[0042] Table 1: Sheet resistance and resistance test results of fiber fabric and electrothermal assembly of each example

[0043] As can be seen from Table 1 and Figure 4 , with the increase of temperature, the resistance change rate gradually increases, and after 300℃, the change is more obvious. When the oxidation temperature reaches 420℃, the graphene is oxidized to a high degree, and uneven white spots appear on the surface of the device (as shown in Figure 5 ), indicating that the graphene has been completely oxidized and does not conduct electricity, and uneven resistance and uneven heating will occur. When the oxidation temperature is 150℃, the graphene is not oxidized, and the resistance does not change.

[0044] Experimental Example 3 Scanning electron microscope test was performed on the graphene glass fiber fabric and graphene fiber electrothermal assembly prepared in Example 5 and Example 7, and the results are shown in Figure 6-a , Figure 6-b , Figure 6-cAs shown in the figures, it can be seen that the sample surface is still intact and the microstructure is not damaged when the oxidation temperature is 360°C and 400°C.

[0045] Experimental Example 4 The infrared radiation diagram of the graphene glass fiber fabric and graphene fiber electrothermal assembly prepared in Example 7 tested under 120V AC voltage is shown in Figure 7-a 、 Figure 7-b and Figure 8 , wherein each sample has 9 temperature measuring points; it can be seen from Figure 7-a 、 Figure 7-b that when the oxidation temperature is 400°C, the infrared radiation temperature decreases under the same voltage, but the heat generation is still very uniform; Figure 8 further proving the uniformity of heat generation.

[0046] Obviously, the above examples are only examples for the purpose of clarity and do not limit the embodiments. Based on the above description, other different forms of changes or variations can also be made by those of ordinary skill in the art. It is not necessary and impossible to enumerate all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A graphene fiber electric heating component, characterized in that: It includes a substrate, an electrothermal functional layer conformally coated on the surface of the substrate, and a resistance control layer conformally coated on the surface of the electrothermal functional layer; The substrate is a fiber or a product thereof, the electrothermal functional layer is a graphene film, and the resistance regulating layer is a graphene oxide film.

2. The graphene fiber electric heating component according to claim 1, characterized in that: The matrix includes chopped fibers or a fiber blanket processed therefrom, or continuous long fibers or a fiber fabric formed by weaving thereof.

3. The graphene fiber electric heating component according to claim 2, characterized in that: The fibers include quartz fibers, glass fibers, alumina fibers, ceramic fibers, silicon carbide fibers or boron fibers.

4. The graphene fiber electric heating component according to claim 1, characterized in that: The square resistance of the graphene fiber electric heating component is 100Ω·sq -1 -5000Ω·sq -1 .

5. The graphene fiber electric heating component according to claim 1, characterized in that: The thickness of the electrothermal functional layer is 50nm-100nm; And / or, the resistance control layer has a thickness of 5 nm to 10 nm.

6. A method for preparing the graphene fiber electric heating component according to any one of claims 1 to 5, characterized in that: The method includes the following steps: (1) introducing carbon source gas to deposit and grow a graphene film on the surface of the substrate to obtain a graphene fiber fabric; (2) Oxidizing the graphene fiber fabric at 200° C.-400° C. to form a graphene oxide film, thereby obtaining a graphene fiber electric heating component.

7. The method for preparing the graphene fiber electric heating component according to claim 6, characterized in that: The oxidation method includes: Oxidizing the graphene fiber fabric in a muffle furnace or a heating platform under air atmosphere; Alternatively, the graphene fiber fabric is oxidized in a tube furnace under an oxygen atmosphere.

8. The method for preparing the graphene fiber electric heating component according to claim 7, characterized in that: The oxidation time is 1 h to 5 h.

9. The method for preparing the graphene fiber electric heating component according to claim 6, characterized in that: The deposition step comprises: heating the temperature to 900-1100° C. at a heating rate of 10-20° C. / min, maintaining the pressure at 10-100 Pa, and depositing for 1-3 hours.

10. An electric heating device, comprising the graphene fiber electric heating component according to any one of claims 1 to 5 or the graphene fiber electric heating component prepared by the preparation method according to any one of claims 6 to 9, and electrodes located on both sides of the graphene fiber electric heating component.

Images