A biomass-based silicon carbide composite fiber and a preparation method thereof and an electromagnetic absorption material

Abstract

The present invention relates to the technical field of carbon fiber materials and composite materials preparation thereof, specifically a biomass-based silicon carbide composite fiber and a preparation method thereof and an electromagnetic absorption material. The present invention provides a biomass-based silicon carbide composite fiber, comprising a hollow carbon fiber and silicon carbide composited in the hollow carbon fiber; the hollow carbon fiber is a carbide of tree cotton fiber. The composite fiber provided by the present invention selects tree cotton fiber with a hollow morphology, high hollowness and large specific surface area as a raw material, and the hollow carbon fiber obtained after carbonization treatment is used as a carbon source to carry out a carbon thermal reduction reaction to introduce a silicon carbide phase to realize a carbon / silicon carbide composite fiber. Under the action of a catalyst, the silicon carbide component can shuttle inside the hollow carbon tube, increase the interface of the composite material and adjust its dielectric constant, so as to optimize the electromagnetic absorption performance; it can realize the application in the electrochemical direction, improve the economic added value of the tree cotton fiber and show multifunctional application.

Description

Technical Field

[0001] The invention relates to the technical field of carbon fiber materials and composite material preparation thereof, in particular to a biomass-based silicon carbide composite fiber and a preparation method thereof and an electromagnetic absorption material. Background Art

[0002] As a new type of multifunctional fiber material, carbon fiber has excellent mechanical and electrical properties, which makes it show great application prospects in the field of high-performance composite materials and new functional materials. Carbon fiber material is a typical conductive loss material and is widely used in the field of electromagnetic wave absorption. In order to improve the absorption performance, carbon / silicon carbide composite material is a potential composite absorbing material with advantages such as good chemical stability. The introduction of SiC component in the composite fiber increases the interface between SiC and C, enhances the interface polarization loss capacity, and significantly improves the absorption performance of the composite material. However, due to the high conductivity of carbon fiber raw materials, it is easy to produce impedance mismatch phenomenon, causing the reflection of electromagnetic waves, affecting its electromagnetic absorption performance. Summary of the invention

[0003] In view of this, the technical problem to be solved by the present invention is to provide a biomass-based silicon carbide composite fiber and a preparation method thereof and an electromagnetic absorption material. The preparation method provided by the present invention can prepare biomass-based silicon carbide composite fibers with high hollowness, light weight and large specific surface area. The preparation method is simple and the process is easy to control.

[0004] The invention provides a biomass-based silicon carbide composite fiber, comprising a hollow carbon fiber and silicon carbide composited on the hollow carbon fiber; the hollow carbon fiber is a carbide of tree cotton fiber.

[0005] The composite fiber of the present invention includes hollow carbon fibers. Specifically, the hollow carbon fibers of the present invention are carbides of tree cotton fibers; the hollowness of the hollow carbon fibers is 85% to 90%; the fiber diameter of the hollow carbon fibers is 10 μm to 15 μm; and the carbon wall thickness of the hollow carbon fibers is 500 nm to 1000 nm.

[0006] Tree cotton is the pappus fiber produced by the fruit of the wild plant shrub fiber species, the ox-horned melon, which was accidentally discovered on the edge of the primitive forest in Yunnan. It is the second plant fiber that has been produced 100% at one time after cotton, which has been the only plant fiber in the world for thousands of years. Tree cotton has its own excellent properties far exceeding cotton, with high hollowness; its specific gravity is one-fourth of cotton fiber, and it can float in the air. Tree cotton fiber can be used as a biomass template for subsequent carbonization to obtain hollow carbon tube fiber. During the carbonization process, the tree cotton fiber including cellulose, hemicellulose, lignin, wax and a small amount of ash will be cracked during the high-temperature carbonization process to generate single carbon material. In some embodiments of the present invention, the hollowness of the tree cotton fiber is 85% to 90%; the fiber length of the tree cotton fiber is 31mm to 35mm; the fiber fineness of the tree cotton fiber, that is, the fiber diameter or cross-sectional area, is 16μm to 28μm.

[0007] The composite fiber of the present invention further comprises silicon carbide compounded to the hollow carbon fiber. The silicon carbide of the present invention is compounded to the interior of the hollow carbon fiber and to the tube wall of the hollow carbon fiber. In certain embodiments of the present invention, the composite fiber further comprises silicon carbide nanowires dispersed inside the hollow carbon fiber and silicon carbide particles compounded in situ to the tube wall of the hollow carbon fiber.

[0008] The biomass-based silicon carbide composite fiber provided by the present invention adopts the carbide of tree cotton fiber as the hollow carbon fiber, utilizes the hollow and light weight characteristics of the tree cotton fiber, and composites silicon carbide on the hollow carbon fiber; the introduction of SiC component in the composite fiber increases the interface between SiC and C, enhances the interface polarization loss capacity, and significantly improves the wave absorption performance of the composite material; the defects and porous structure of the hollow lightweight multi-walled carbon nanotubes prepared based on the hollow biomass fiber as a template also enhance the dielectric loss performance of the system; and the dielectric properties of the composite material can be regulated by adjusting the content of the introduced silicon carbide component, which further improves the wave absorption performance of the composite material.

[0009] The present invention also provides a method for preparing biomass-based silicon carbide composite fibers, comprising the following steps: subjecting hollow carbon fibers to a solid phase reaction with a silicon source to obtain biomass-based silicon carbide composite fibers; the hollow carbon fibers are carbides of tree cotton fibers.

[0010] The hollow carbon fiber of the present invention is the carbonization of tree cotton fiber. The present invention selects tree cotton fiber, a biomass fiber with a unique hollow morphology, as a raw material, wherein the hollowness is high and the hollow lightness is a hollow property. Using this as a template, the hollow carbon fiber can be prepared by carbonization treatment under the protection of an inert gas. Specifically, the present invention carbonizes the tree cotton fiber under the protection of an inert gas to obtain the carbonization of the tree cotton fiber, i.e., the above-mentioned hollow carbon fiber. In certain embodiments of the present invention, the hollowness of the tree cotton fiber is 85% to 90%; the fiber length of the tree cotton fiber is 31mm to 35mm; the fiber diameter of the tree cotton fiber is 16μm to 28μm. In certain embodiments of the present invention, the inert gas is nitrogen, and the purity of the nitrogen is above 99.99%. In certain embodiments of the present invention, the temperature of the carbonization treatment is 600℃ to 800℃, the time of the carbonization treatment is 1h to 6h; the heating rate of the carbonization treatment is 1℃ / min to 5℃ / min, preferably 1℃ / min. In one embodiment, the temperature of the carbonization treatment is 800° C., the time of the carbonization treatment is 2 h, and the heating rate of the carbonization treatment is 2° C. / min.

[0011] After the hollow carbon fiber is prepared by the present invention, the carbon / silicon carbide composite fiber can be prepared by using it as a carbon source for carbon thermal reduction reaction to introduce silicon carbide phase. The present invention conducts a solid-phase reaction between the hollow carbon fiber and the silicon source to obtain a biomass-based silicon carbide composite fiber. In certain embodiments of the present invention, the hollow carbon fiber is mixed with the silicon source and then sintered at high temperature in an inert protective gas atmosphere for solid-phase reaction to obtain a biomass-based silicon carbide composite fiber; after naturally cooling to room temperature, a hollow carbon / silicon carbide composite fiber is obtained. In certain embodiments of the present invention, the hollowness of the hollow carbon fiber obtained above is 85% to 90%; the fiber diameter of the hollow carbon fiber is 10μm to 15μm; the carbon wall thickness of the hollow carbon fiber is 500nm to 1000nm. In certain embodiments of the present invention, the mass ratio of the hollow carbon fiber to the silicon source is 4 to 10:1, preferably 6:1. In some embodiments of the present invention, the silicon source is selected from at least one of silicon dioxide, silicon powder, sodium silicate, methyl orthosilicate (TMOS) and ethyl orthosilicate (TEOS). In one embodiment, the silicon source is selected from silicon dioxide and silicon powder in a molar ratio of 1:1.

[0012] In some embodiments, the temperature of the solid phase reaction is 1000°C to 1300°C, preferably 1100°C; the time of the solid phase reaction is 30min to 180min, preferably 2h; the heating rate of the solid phase reaction is 1°C / min to 3°C / min, preferably 2.5°C / min. In some embodiments, the inert protective gas is selected from at least one of helium or argon, and the flow rate of the inert protective gas is 10mL / min to 20mL / min. In one embodiment, the inert protective gas is argon, and the flow rate of the inert protective gas is 10mL / min.

[0013] The present invention further includes catalytically treating the hollow carbon fibers before subjecting the hollow carbon fibers to a solid-phase reaction with a silicon source. Specifically, the present invention immerses the hollow carbon fibers in a catalyst solution for catalytic treatment; the catalytic treatment can facilitate the subsequent generation of silicon carbide. In certain embodiments of the present invention, the temperature of the catalytic treatment is 30°C to 80°C; the time of the catalytic treatment is 0.5h to 10h. In certain embodiments of the present invention, the catalytic treatment is carried out in one or more solutions of disodium ethylenediaminetetraacetic acid, sodium chloride, sodium fluoride, FeCl3·6H2O and Co(NO3)2. In one embodiment, the catalytic treatment is carried out in a mixed solution of disodium ethylenediaminetetraacetic acid at a concentration of 0.02mol / L and FeCl3·6H2O at a concentration of 0.2mol / L.

[0014] The present invention further includes pre-treating the above-mentioned hollow carbon fiber before the above-mentioned catalytic treatment with the silicon source. The present invention pre-treats the above-mentioned hollow carbon fiber to increase the roughness and functional groups on the surface of the carbon fiber, which can facilitate the subsequent loading of the catalyst and the reaction with the silicon source to generate silicon carbide. In certain embodiments of the present invention, the temperature of the pre-treatment is 30°C to 65°C; the time of the pre-treatment is 0.5h to 2h. In certain embodiments of the present invention, the pre-treatment is carried out in one or more of hydrofluoric acid, dilute hydrochloric acid, dilute sulfuric acid, hypochlorous acid, hydrogen peroxide, and ammonia. In some embodiments, the present invention pre-treats the above-mentioned hollow carbon fiber by successively immersing it in one or more of hydrofluoric acid, dilute hydrochloric acid, dilute sulfuric acid, hypochlorous acid, hydrogen peroxide, and ammonia. In one embodiment, the present invention immerses the above-mentioned hollow carbon fiber in 40wt% hydrofluoric acid for 4h.

[0015] The present invention also provides an electromagnetic absorption material, comprising a fiber material and an insulating material; the fiber material is the composite fiber mentioned above or the composite fiber prepared by the method mentioned above.

[0016] The present invention provides a biomass-based silicon carbide composite fiber, comprising a hollow carbon fiber and silicon carbide composited in the hollow carbon fiber; the hollow carbon fiber is a carbide of tree cotton fiber. The biomass-based silicon carbide composite fiber provided by the present invention selects tree cotton fiber with a unique hollow morphology, a high hollowness and a large specific surface area as a raw material, and then performs a carbon thermal reduction reaction to introduce a silicon carbide phase to achieve the preparation of carbon / silicon carbide composite fibers, that is, the preparation of biomass-based silicon carbide composite fibers. Under the action of a catalyst, the silicon carbide component can shuttle inside the hollow carbon tube, increase the interface of the composite material and adjust its dielectric constant, which can optimize the electromagnetic absorption performance, realize the application in the electrochemical direction, enhance the economic added value of the tree cotton biomass fiber, and show multifunctional application. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the XRD pattern of the hollow carbon fiber material obtained in Example 1;

[0018] Figure 2 This is a SEM image of the hollow carbon fiber material obtained in Example 1;

[0019] Figure 3 This is a SEM image of the hollow carbon / silicon carbide composite fiber obtained in Example 1;

[0020] Figure 4 The dielectric constant diagram of the hollow carbon fiber material obtained in Example 1;

[0021] Figure 5 This is the magnetic permeability diagram of the hollow carbon fiber material obtained in Example 1;

[0022] Figure 6 The dielectric constant diagram of the hollow carbon / silicon carbide composite fiber obtained in Example 1;

[0023] Figure 7 This is the magnetic permeability diagram of the hollow carbon / silicon carbide composite fiber obtained in Example 1. DETAILED DESCRIPTION

[0024] The present invention discloses a biomass-based silicon carbide composite fiber and a preparation method thereof and an electromagnetic absorption material. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve it. It is particularly important to point out that all similar substitutions and modifications are obvious to those skilled in the art, and they are all deemed to be included in the present invention. The method and application of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the method and application of this article without departing from the content, spirit and scope of the present invention to realize and apply the technology of the present invention.

[0025] The present invention will be further described below in conjunction with embodiments:

[0026] Example 1

[0027] The biomass-based FeS particle composite fiber of the present invention is prepared according to the following steps:

[0028] Step 1: prepare hollow carbon tube fibers, select tree cotton fibers, a biomass fiber material, as raw materials, and obtain hollow carbon fiber materials after carbonization treatment; the carbonization treatment is to heat the temperature to 800°C for high-temperature treatment under the protection of inert gas nitrogen with a gas purity of ≥99.99%, maintain a slow heating rate of 2°C / min, and keep warm for 2 hours.

[0029] Step 2: Pretreatment of carbon fiber, pretreatment of the hollow carbon material obtained in step 1 to increase the roughness and functional groups on the surface of the carbon fiber to facilitate the subsequent loading of the catalyst and the reaction with the silicon source to generate silicon carbide; the pretreatment is to use 40wt% hydrofluoric acid immersion treatment for 4 hours and then wash with deionized water multiple times.

[0030] Step 3: Impregnation of catalyst: the pre-treated carbon fiber material is immersed in a catalyst solution for subsequent silicon carbide generation at 40°C for 2 hours. Specifically, the catalyst solution is a mixed solution of 0.02 mol / L EDTA disodium ethylenediaminetetraacetic acid and 0.2 mol / L FeCl3·6H2O.

[0031] Step 4: Solid phase reaction with silicon source, the carbon fiber obtained in step 3 is reacted with silicon source in solid phase to generate silicon carbide, that is, hollow carbon / silicon carbide composite fiber is obtained; the silicon source is a mixture of silicon dioxide and silicon powder with a molar ratio of 1:1. The specific operation is as follows: the carbon fiber obtained in step 3 is mechanically mixed with the above silicon source at a mass ratio of 6:1, and then placed in a crucible and placed in a sintering furnace. Argon with a gas flow rate of 10mL / min is used as an inert protective gas, and the temperature is increased to 1100℃ at a heating rate of 2.5℃ / min for high temperature sintering reaction for 2h. After the reaction is completed, it is naturally cooled to room temperature to obtain a hollow carbon / silicon carbide composite fiber.

[0032] The hollow carbon fiber material obtained in step 1 of this embodiment was subjected to XRD and SEM testing, and the hollow carbon / silicon carbide composite fiber obtained in step 4 was subjected to SEM testing. The test results are as follows: Figures 1 to 3 shown. Figure 1 The XRD pattern of the hollow carbon fiber material obtained in Example 1 is shown in FIG. Figure 1 It can be seen that the tree cotton fiber is completely converted into amorphous elemental carbon after carbonization treatment under inert gas protection at 800°C. Figure 2 This is the SEM image of the hollow carbon fiber material obtained in Example 1. Figure 2It can be seen that the carbon fiber morphology prepared after carbonization treatment replicates the hollow morphology of tree cotton and is a hollow carbon fiber; its surface shrinks and produces wrinkles, the fiber diameter is 10-15 μm, and the carbon wall thickness is about 500-1000 nm. Figure 3 The SEM image of the hollow carbon / silicon carbide composite fiber obtained in Example 1 is shown in FIG. Figure 3 It can be seen that the silicon carbide component is successfully introduced after the solid-phase carbothermal reduction reaction of the silicon source. The silicon carbide has two typical morphologies, namely, SiC generated in situ on the carbon tube wall and nanowires dispersed inside the hollow carbon tube.

[0033] The hollow carbon fiber material obtained in step 1 was tested for electromagnetic parameters and wave absorption performance. The results are as follows: Figures 4-5 As shown, Figure 4 The dielectric constant diagram of the hollow carbon fiber material obtained in Example 1, Figure 5 This is the magnetic permeability diagram of the hollow carbon fiber material obtained in Example 1. Figures 4-5 It can be seen that the real part and the imaginary part of the magnetic permeability of the hollow carbon fiber material obtained in step 1 of Example 1 are concentrated near 1 and 0, respectively, which belongs to the magnetic permeability data characteristics of the composite dielectric lossy absorbing material; its dielectric constant is artificially high, and the imaginary part of the dielectric constant is higher than the real part, which will cause impedance matching mismatch and seriously affect its absorbing performance.

[0034] The electromagnetic parameters and wave absorption performance of the hollow carbon / silicon carbide composite fiber obtained in step 4 were tested. Figures 6-7 As shown, Figure 6 The dielectric constant diagram of the hollow carbon / silicon carbide composite fiber obtained in Example 1 is shown in FIG. Figure 7 The magnetic permeability diagram of the hollow carbon / silicon carbide composite fiber obtained in Example 1. Figures 6-7 It can be seen that the dielectric constant of the hollow carbon / silicon carbide composite fiber obtained in step 4 of Example 1 is significantly lower than that of the hollow carbon fiber material obtained in step 1; and the real part of its dielectric constant is greater than the imaginary part, which proves that the introduction of the silicon carbide component has a positive effect on the regulation of dielectric properties. Subsequent adjustment of the process can achieve excellent wave absorbing performance.

[0035] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A biomass-based silicon carbide composite fiber, characterized in that: It includes hollow carbon fibers and silicon carbide compounded in the hollow carbon fibers; The hollow carbon fiber is a carbonized product of tree cotton fiber; The hollowness of the hollow carbon fiber is 85% to 90%; The fiber diameter of the hollow carbon fiber is 10 μm to 15 μm; The carbon wall thickness of the hollow carbon fiber is 500 nm to 1000 nm; The method for preparing the biomass-based silicon carbide composite fiber comprises the following steps: The hollow carbon fibers are reacted with a silicon source in a solid phase to obtain biomass-based silicon carbide composite fibers; The carbonized tree cotton fiber is prepared by carbonizing tree cotton fiber as a raw material; the temperature of the carbonization treatment is 600° C. to 800° C., and the time of the carbonization treatment is 1 h to 6 h; The hollowness of the tree cotton fiber is 85% to 90%; The fiber diameter of the tree cotton fiber is 16 μm to 28 μm; The hollow carbon fiber is subjected to catalytic treatment before solid phase reaction; the temperature of the catalytic treatment is 30°C to 80°C; the time of the catalytic treatment is 0.5 h to 10 h; the catalytic treatment is carried out in one or more solutions of disodium ethylenediaminetetraacetic acid, sodium chloride, sodium fluoride, FeCl3•6H2O and Co(NO3)2; Before the above-mentioned hollow carbon fiber and silicon source are subjected to the above-mentioned catalytic treatment, the above-mentioned hollow carbon fiber is also subjected to pretreatment; the temperature of the pretreatment is 30°C~65°C; the time of the pretreatment is 0.5 h~2 h; the pretreatment is carried out in one or more of hydrofluoric acid, dilute hydrochloric acid, dilute sulfuric acid, hypochlorous acid, hydrogen peroxide, and ammonia water.

2. The biomass-based silicon carbide composite fiber according to claim 1, characterized in that: The silicon source is selected from at least one of silicon dioxide, silicon powder, sodium silicate, methyl orthosilicate and ethyl orthosilicate.

3. The biomass-based silicon carbide composite fiber according to claim 1, characterized in that: The mass ratio of the hollow carbon fiber to the silicon source is 4-10:

1.

4. The biomass-based silicon carbide composite fiber according to claim 1, characterized in that: The temperature of the solid phase reaction is 1000° C. to 1300° C.; the time of the solid phase reaction is 30 min to 180 min.

5. An electromagnetic absorption material, characterized in that: It comprises fiber material and insulating material; the fiber material is the biomass-based silicon carbide composite fiber as described in any one of claims 1 to 4.

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