Surface-roughened SiC / C nanocomposite fiber and preparation method and application thereof

Abstract

The application discloses a surface-rough SiC / C nanometer composite fiber and a preparation method and application thereof. The surface-rough SiC / C nanometer fiber with good electromagnetic wave absorption performance is prepared by electrostatic spinning and high-temperature pyrolysis, with soluble precursor PCS and polymer PVP as initial materials, with tetrahydrofuran and dimethylformamide as solvents, and with acetylacetone zinc as an additive. The addition of acetylacetone zinc not only effectively improves the structural stability of the SiC / C, but also effectively widens the effective absorption width of the composite fiber by designing the surface-rough structure. The application has simple process, and the prepared fiber has good one-dimensional morphology and exhibits excellent electromagnetic wave absorption performance.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of electromagnetic wave absorbing materials, and in particular relates to a rough-surfaced SiC / C nanocomposite fiber and a preparation method and application thereof. Background Art

[0002] With the development of electromagnetic technology and electronic devices, electromagnetic pollution poses an increasing threat to human health and precision electronic equipment, making electromagnetic wave absorption a hot topic of research. Absorbing materials can effectively absorb or attenuate incoming electromagnetic waves, converting electromagnetic energy into internal energy or other forms of energy loss, thereby fundamentally preventing the harm of electromagnetic waves and attracting widespread attention from researchers. However, with the diverse demands of various application fields, absorbing materials no longer simply emphasize strong attenuation, but also have higher requirements for lightweight and broadband performance, making the development of new absorber materials with excellent performance particularly important.

[0003] One-dimensional (1D) SiC materials have attracted considerable attention due to their high strength, high modulus, low density, excellent oxidation resistance, chemical stability, and good dielectric and electromagnetic properties. When used as absorbers, their 1D structure, compared to bulk and particle structures, facilitates the construction of an internal conductive network, thereby improving the system's conductive losses. However, several challenges remain. First, pure SiC exhibits a low dielectric constant, which typically requires compounding and structural design to increase its dielectric constant to optimize the system's electromagnetic wave impedance matching performance and loss capacity. Existing SiC fibers have a narrow effective absorption bandwidth, concentrated in the high-frequency region. Therefore, there is an urgent need to develop efficient, broadband SiC fiber absorbers. Furthermore, the introduction of metallic elements (such as iron, cobalt, nickel, and molybdenum) has been shown to be an effective method for improving the electromagnetic attenuation properties of SiC fibers. However, due to its unique properties as a low-temperature, readily sublimable material, Zn has not yet been applied to the structural design and performance optimization of SiC fibers. Therefore, the introduction of zinc source into the SiC / C fiber system for rough structure design was explored to improve the electromagnetic wave absorption performance of SiC / C fibers, in the hope of preparing lightweight rough SiC / C nanofibers with excellent wave absorption properties. Summary of the Invention

[0004] The present invention provides a rough-surfaced SiC / C nanocomposite fiber and its preparation method and application for obtaining a nanofiber absorbing material with excellent wave absorbing performance. The preparation conditions are easy to achieve and the operation is simple. A simple electrospinning method and a high-temperature pyrolysis process are mainly used to obtain SiC / C nanofibers with a rough surface, good nanofiber morphology and excellent electromagnetic wave absorption performance.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing a rough-surfaced SiC / C nanocomposite fiber, comprising the following steps:

[0007] Polycarbosilane and zinc acetylacetonate were dissolved in tetrahydrofuran to obtain solution A, polyvinylpyrrolidone was added into dimethylformamide to obtain solution B, and solution A and solution B were stirred continuously until they were uniform;

[0008] Adding the uniform solution A to the uniform solution B and mixing them evenly to obtain a spinning solution;

[0009] According to the preset spinning conditions, the spinning solution is used to spin the precursor fiber;

[0010] performing a pre-oxidation treatment on the precursor fiber to obtain a pre-oxidized fiber;

[0011] The pre-oxidized fibers were sintered in a N2 atmosphere and annealed to obtain SiC / C nanocomposite fibers with rough surfaces.

[0012] The mass volume ratio of the polycarbosilane, zinc acetylacetonate and tetrahydrofuran is (0.5-1.0) g: (0.1-0.2) g: (4-8) mL.

[0013] The mass volume ratio of the polyvinyl pyrrolidone and dimethylformamide is (0.5-1.0) g: (2-4) mL.

[0014] The preset spinning conditions include:

[0015] The spinning speed is 0.1~0.4mm / min, the voltage is 15~20kv, the distance between the collecting drum and the spinneret is 15~20cm, and the rotation speed is 80~100r / min.

[0016] The temperature of the pre-oxidation treatment is 100-200° C., and the time is 2-4 hours.

[0017] The stirring time for continuously stirring solution A and solution B until they are uniform is 0.5 to 1.0 h.

[0018] The solution A in a uniform state is added to the solution B in a uniform state and mixed evenly to obtain a spinning solution, specifically:

[0019] The homogeneous solution A is added to the homogeneous solution B, and the mixture is magnetically stirred for 12 to 24 hours to obtain a spinning solution.

[0020] The sintering temperature is 1100-1200°C and the time is 2-3 hours; the heating rate of the annealing treatment is 2-5°C / min, the temperature is 1200-1300°C and the time is 2-4 hours.

[0021] The present invention also provides a rough-surfaced SiC / C nanocomposite fiber prepared according to the above preparation method, wherein the average diameter of the SiC / C nanocomposite fiber is about 450 nm.

[0022] The rough-surfaced SiC / C nanocomposite prepared by the invention is applied in the field of electromagnetic wave absorption.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention discloses a method for preparing surface-roughened SiC / C nanocomposite fibers. These SiC / C nanofibers possess the structural advantage of interlaced one-dimensional structures, facilitating the establishment of an internal conductive network. This facilitates electron migration within the fibers and interfiber transitions, effectively enhancing electrical conductivity losses. The introduction of a Zn-containing raw material effectively forms a roughened structure within the SiC / C fibers, exhibiting a distinct phase characteristic peak at 1200°C. This roughened structure effectively increases the interfacial area of ​​the system, significantly improving its electromagnetic wave absorption performance. The nanocomposite fibers prepared by this method have broad application prospects in electromagnetic wave absorption. The spinning solution is prepared using PCS dissolved in tetrahydrofuran as the silicon carbide source and PVP to adjust the viscosity of the spinning solution. Notably, the addition of zinc acetylacetonate or zinc acetate has little effect on the viscosity of the spinning solution, and thus, on spinnability. Precursor nanofibers are prepared through an electrospinning process, followed by air pre-oxidation and subsequent high-temperature sintering to obtain surface-roughened SiC / C composite nanofibers with excellent electromagnetic wave absorption properties.

[0025] Furthermore, the mass volume ratio of polycarbosilane: zinc acetylacetonate (zinc acetate): tetrahydrofuran is (0.5~1.0) g: (0.1~0.2) g: (4~8) mL, and the ratio is optimized, which not only ensures SiC / C as the matrix fiber, but also designs its structure by introducing zinc-containing raw materials. Because PCS is not easily soluble in other solvents, there should be a sufficient amount of tetrahydrofuran to ensure the full dissolution of PCS and zinc-containing raw materials.

[0026] Furthermore, the mass volume ratio of PVP:DMF is (0.5~1.0)g:(2-5)mL. By controlling the ratio of PVP and DMF, the dissolution efficiency of PVP is ensured, and the influence of solution viscosity on spinning performance is comprehensively considered to improve the stability of the spinning process.

[0027] Furthermore, PCS and PVP were dissolved in tetrahydrofuran and DMF respectively, so that PCS and PVP were fully dissolved, and stirred for a sufficient time to disperse them evenly and avoid agglomeration, which was beneficial to the full mixing of the solution in the next step and ensured the quality of the spinning solution.

[0028] Furthermore, the mixed solution needs to be stirred for an appropriate time to form a uniform and stable spinning solution because the solvents need to be mutually soluble and the solutes need to diffuse in the mixed solution, so as to avoid problems such as uneven spinning and blockage caused by uneven spinning solution.

[0029] Furthermore, sufficient voltage is required to ensure that there is sufficient electrostatic traction between the spinning needle and the collecting device to form nanofibers. Too low a voltage will result in insufficient traction and the fibers cannot be fully stretched. The spinning speed should not be too fast or too slow. If the spinning speed is too fast, the spinning liquid cannot be fully stretched in time under the action of electrostatics, resulting in the fibers being too thick or uneven in shape. If the spinning speed is too slow, the spinning process becomes inefficient and may even cause blockage due to excessive accumulation of spinning liquid at the needle. An appropriate spinning speed ensures that the evenly injected spinning liquid can be fully stretched into fibers under the action of electrostatics. The collection distance and the drum speed both need to be within an appropriate range to ensure that the spun fibers are collected as much as possible without changing their original shape. If the collection distance is too close, the fibers will stick together due to incomplete solidification. If the speed is too fast, the fibers will be deformed due to excessive mechanical force.

[0030] Furthermore, the conditions set for the pre-oxidation treatment can fully volatilize the solvent in the fiber and stabilize the fiber morphology. Too high a temperature will cause the solvent in the fiber to evaporate quickly and cause shrinkage or deformation, while too low a temperature will reduce the volatilization efficiency of the solvent.

[0031] Furthermore, N2 is a commonly used inert gas with stable chemical properties. Sintering the pre-oxidized fiber in an N2 atmosphere can ensure the purity of the fiber and prevent the fiber from being oxidized and ablated. For the fiber firing system, the heating rate must be within a certain range. The heating rate is one of the factors affecting the fiber morphology. If the sintering temperature is too high or the temperature rises too quickly, the thermal stress inside the fiber will increase sharply, which may lead to the destruction of the fiber structure and the breakage of the fiber. PCS cannot be converted into SiC in time, affecting the performance of the fiber.

[0032] A rough SiC / C nanocomposite fiber is a high-performance absorbing material. Through the design of the present invention, the rough SiC / C nanocomposite fiber can construct an internal conductive network, and the rough structure increases the interface area, thereby increasing the real and imaginary parts of the dielectric constant, enhancing reflection loss, and significantly increasing the effective absorption width, thereby significantly improving the electromagnetic wave absorption performance of the rough SiC / C nanocomposite fiber.

[0033] In summary, the method of the present invention is simple in process, and the prepared composite nanofibers have complete morphology, uniform diameter distribution, increased roughness, and exhibit excellent microwave absorbing properties.

[0034] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments:

[0036] Figure 1 This is an SEM image of the SiC / C nanofibers prepared in Example 1 without the introduction of zinc-containing raw materials;

[0037] Figure 2 This is the SEM image of the rough surface SiC / C nanofibers prepared in Example 2;

[0038] Figure 3 XRD comparison of SiC / C nanofibers prepared in Examples 1, 2, and 3 with and without the introduction of zinc-containing raw materials, wherein the sintering temperature is 1200°C, and Figures 1 and 2 represent the addition of 0.1g and 0.2g of zinc acetylacetonate, respectively;

[0039] Figure 4 3D reflection loss graphs of SiC / C nanofibers prepared in Examples 1 and 2 with and without the introduction of zinc-containing raw materials as absorbing materials, where (a) is the 3D reflection loss graph without the introduction of zinc-containing raw materials, and (b) is the 3D reflection loss graph with the introduction of zinc-containing raw materials;

[0040] Figure 5 The real part (a) and imaginary part (b) of the dielectric constant of SiC / C nanofibers prepared with and without the introduction of zinc-containing raw materials for Examples 1, 2, and 3, where 1 and 2 represent the addition amount of zinc acetylacetonate of 0.1 g and 0.2 g, respectively;

[0041] Figure 6 The effective absorption width of the surface roughened SiC / C-1 prepared in Example 2 at different thicknesses. DETAILED DESCRIPTION

[0042] The technical solution of the present invention will be described clearly and completely below. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0043] In the present invention, unless otherwise specified, all the embodiments and preferred implementation methods mentioned herein can be combined with each other to form a new technical solution.

[0044] In the present invention, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0045] In the present invention, unless otherwise specified, percentages (%) or parts refer to percentages by weight or parts by weight relative to the composition.

[0046] In the present invention, unless otherwise specified, the components or preferred components involved can be combined with each other to form a new technical solution.

[0047] In this disclosure, unless otherwise specified, the numerical range "a-b" is an abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "6-22" indicates that all real numbers between "6-22" are listed herein, and "6-22" is merely an abbreviation for these numerical combinations.

[0048] The "range" disclosed in the present invention is in the form of a lower limit and an upper limit, which can be one or more lower limits, and one or more upper limits, respectively.

[0049] In the present invention, the term "and / or" used herein refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0050] In the present invention, unless otherwise specified, each reaction or operation step can be carried out sequentially or in accordance with the sequence. Preferably, the reaction method herein is carried out sequentially.

[0051] Unless otherwise indicated, the professional and scientific terms used herein are the same as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content can also be applied to the present invention.

[0052] The present invention provides a surface-roughened SiC / C nanocomposite fiber and its preparation method and application. Polycarbosilane (PCS) and zinc acetylacetonate are dissolved in tetrahydrofuran solvent in a certain proportion, and PVP is dissolved in DMF solvent in a certain proportion to prepare uniform solutions. The two solutions are mixed and stirred for a sufficient time to achieve uniformity, and the resulting uniform solution is electrospun to produce a Zn-containing SiC / C precursor fiber with a specific composition. The precursor fiber is pyrolyzed at high temperature in an inert atmosphere to produce the desired surface-roughened SiC / C nanofiber. The surface-roughened SiC / C nanofiber is mixed with paraffin wax in a certain proportion to prepare a dielectric sample, and its electromagnetic wave absorption performance is tested. The addition of zinc acetylacetonate not only effectively improves the structural stability of the SiC / C, but also effectively broadens the effective absorption bandwidth of the composite fiber due to the surface-roughened structure. This invention is the first to use zinc acetylacetonate as an additive to prepare SiC / C nanofibers with a rough surface and excellent electromagnetic wave absorption performance through electrospinning and high-temperature pyrolysis.

[0053] The present invention provides a method for preparing a rough-surfaced SiC / C nanocomposite fiber, comprising the following steps:

[0054] S1. Place polycarbosilane (PCS) and zinc acetylacetonate in a weighing bottle and dissolve them in tetrahydrofuran in a certain proportion to obtain solution A. Place polyvinylpyrrolidone (PVP) in a weighing bottle and add dimethylformamide (DMF) to obtain solution B. Stir the obtained solutions A and B separately on a magnetic stirrer for 0.5-1.0 h until they are homogeneous.

[0055] The mass volume ratio of polycarbosilane: zinc acetylacetonate: tetrahydrofuran is (0.5~1.0) g: (0.1~0.2) g: (4~8) mL; the mass volume ratio of PVP: DMF is (0.5~1.0) g: (2~4) mL.

[0056] S2. Slowly add the homogeneous solution A obtained in step S1 to the homogeneous solution B under magnetic stirring, and then stir for 12 to 24 hours to fully mix the two solutions to obtain a stable spinning solution;

[0057] S3, controlling the voltage to 15-20 kV, the distance between the collecting drum and the spinneret to 15-20 cm, the rotation speed to 80-100 r / min, and spinning with the spinning solution at a constant speed of 0.1-0.4 mm / min to obtain a precursor fiber;

[0058] Among them, the needle is a 23-gauge needle with an inner diameter of 0.3 mm.

[0059] S4, collecting the precursor fiber obtained in step S3 on aluminum foil, and pre-oxidizing it in a blast drying oven at a temperature of 100-200° C. for 2-4 hours to obtain pre-oxidized fiber;

[0060] S5. Sinter the pre-oxidized fiber obtained in step S4 at 1100-1200° C. for 2-3 h in a N2 atmosphere, heat it to 1200-1300° C. at a rate of 2-5° C. / min, and anneal it for 2-4 h to obtain a rough-surfaced SiC / C nanocomposite fiber.

[0061] The rough surface SiC / C nanocomposite fiber prepared by the present invention not only has the excellent performance of silicon carbide in resisting harsh environments, but also has the morphological characteristics of nanofibers such as high specific surface area and high aspect ratio. The introduction of zinc raw material further realizes the formation of a rough structure.

[0062] Pure silicon carbide fiber has relatively low real and imaginary values ​​of the dielectric constant, mainly characterized by dielectric loss, a narrow effective absorption width and low loss capacity. The introduction of zinc acetylacetonate generates SiC / C nanofibers with a rough surface structure, which significantly improves the effective absorption width and optimal reflection loss.

[0063] In summary, rough-surfaced SiC / C nanocomposite fibers have a simple preparation method and promising microwave absorption properties, and have certain application prospects.

[0064] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0065] Example 1

[0066] 0.5 g of polycarbosilane and 0.1 g of zinc acetylacetonate were weighed and dissolved in 7 mL of tetrahydrofuran. The solution was stirred under magnetic stirring for 0.5 h to obtain a uniform solution A.

[0067] Weigh 0.5 g of PVP and dissolve it in 4 mL of DMF. Stir the solution under magnetic stirring for 0.5 h to obtain a uniform solution B.

[0068] Under magnetic stirring, solution A was slowly added into solution B and magnetic stirring was performed for 12 h until a uniform and stable spinning solution C was formed;

[0069] A No. 23 needle with an inner diameter of 0.3 mm was used, and spinning was performed at a constant speed of 0.2 mm / min using spinning solution C at a voltage of 16 kV, a collecting drum 15 cm away from the spinneret, and a rotation speed of 100 r / min to obtain a precursor fiber;

[0070] The obtained precursor fibers were collected and pre-oxidized in a 200°C forced air drying oven for 2 h to obtain pre-oxidized fibers. The pre-oxidized fibers were then sintered at 1100°C for 3 h in a N2 atmosphere, heated at 2.5°C / min, and annealed at 1200°C for 2 h to obtain SiC / C nanofibers.

[0071] The spinning is uniform and continuous, maintaining the one-dimensional morphology of the nanofibers. Due to the lack of the introduction of Zn salt, the SiC / C fibers have no rough structure.

[0072] Example 2

[0073] 0.5 g of polycarbosilane and 0.15 g of zinc acetylacetonate were weighed and dissolved in 7 mL of tetrahydrofuran. The solution was stirred under magnetic stirring for 0.5 h to obtain a uniform solution A.

[0074] Weigh 0.5 g of PVP and dissolve it in 4 mL of DMF. Stir the solution under magnetic stirring for 0.5 h to obtain a uniform solution B.

[0075] Under magnetic stirring, solution A was slowly added into solution B and magnetic stirring was performed for 12 h until a uniform and stable spinning solution C was formed;

[0076] A No. 23 needle with an inner diameter of 0.3 mm was used, and spinning was performed at a constant speed of 0.2 mm / min using spinning solution C at a voltage of 16 kV, a collecting drum 15 cm away from the spinneret, and a rotation speed of 100 r / min to obtain a precursor fiber;

[0077] The obtained precursor fibers were collected and pre-oxidized in a 150°C forced air drying oven for 3 h to obtain pre-oxidized fibers. The pre-oxidized fibers were then sintered at 1100°C for 3 h in a N2 atmosphere, heated at 2.5°C / min, and annealed at 1200°C for 2 h to obtain SiC / C nanofibers with rough surfaces.

[0078] Due to the unchanged parameters during spinning, the diameter of the fiber remains almost unchanged, and the fiber remains long and continuous as a whole. The introduction of rough structure improves both the real and imaginary parts of the dielectric constant of the system.

[0079] Example 3

[0080] Weigh 0.8 g of polycarbosilane (PCS) and 0.2 g of zinc acetylacetonate, then dissolve them in 7 ml of tetrahydrofuran (THF). Stir the solution under magnetic stirring for 0.5 h to obtain a uniform solution A.

[0081] Weigh 0.5 g of polyvinylpyrrolidone (PVP) and dissolve it in 4 mL of DMF. Stir the solution under magnetic stirring for 0.5 h to obtain a homogeneous solution B.

[0082] Under magnetic stirring, solution A was slowly added to solution B and magnetic stirring was performed for 12 h until a uniform and stable spinning solution C was formed;

[0083] A No. 23 needle with an inner diameter of 0.3 mm was used, and spinning was performed at a constant speed of 0.42 mm / min using spinning solution C at a voltage of 15 kV, a collecting drum 16 cm away from the spinneret, and a rotation speed of 100 r / min to obtain a precursor fiber.

[0084] The obtained precursor fibers were collected and pre-oxidized in a 200°C forced air drying oven for 2 hours to obtain pre-oxidized fibers. The pre-oxidized fibers were then sintered at 1200°C for 3 hours in a N2 atmosphere, with the temperature increased at 5°C / min, and annealed at 1300°C for 2 hours to obtain rough SiC / C nanofibers.

[0085] It can be clearly seen that the increase in the amount of zinc acetylacetonate added increases the viscosity of the solution and makes spinning difficult.

[0086] Example 4

[0087] 1 g of polycarbosilane and 0.18 g of zinc acetylacetonate were weighed and dissolved in 8 mL of tetrahydrofuran. The solution was stirred under magnetic stirring for 0.5 h to obtain a uniform solution A.

[0088] Weigh 1 g of PVP and dissolve it in 4 mL of DMF. Stir the solution under magnetic stirring for 0.5 h to obtain a homogeneous solution B.

[0089] Under magnetic stirring, solution A was slowly added into solution B and magnetic stirring was performed for 12 h until a uniform and stable spinning solution C was formed;

[0090] A No. 23 needle with an inner diameter of 0.3 mm was selected, and spinning was performed with spinning solution C at a constant speed of 0.2 mm / min at a voltage of 20 kV, a collecting drum 15 cm away from the spinneret, and a rotation speed of 100 r / min to obtain a precursor fiber;

[0091] The obtained precursor fibers were collected and pre-oxidized in a 200°C forced air drying oven for 2 h to obtain pre-oxidized fibers. The pre-oxidized fibers were then sintered at 1100°C for 2 h in a N2 atmosphere, heated at 5°C / min, and annealed at 1300°C for 2 h to obtain SiC / C nanofibers with rough surfaces.

[0092] Due to excessive sintering temperature, the fiber becomes more brittle and breaks.

[0093] Example 5

[0094] 0.5 g of polycarbosilane and 0.1 g of zinc acetylacetonate were weighed and dissolved in 7 mL of tetrahydrofuran. The solution was stirred under magnetic stirring for 0.5 h to obtain a uniform solution A.

[0095] Meanwhile, 0.8 g of PVP was weighed and dissolved in 3 mL of DMF, and the solution was stirred under magnetic stirring for 0.5 h to obtain a homogeneous solution B;

[0096] Under magnetic stirring, solution A was slowly added into solution B and magnetic stirring was performed for 12 h until a uniform and stable spinning solution C was formed;

[0097] Then, a No. 23 needle with an inner diameter of 0.3 mm was selected, and spinning was performed at a constant speed of 0.2 mm / min using the spinning solution C at a voltage of 20 kV, a collecting drum 15 cm away from the spinneret, and a rotation speed of 100 r / min to obtain a precursor fiber;

[0098] The obtained precursor fibers were collected and pre-oxidized in a 100°C forced air drying oven for 4 h to obtain pre-oxidized fibers. The pre-oxidized fibers were then sintered at 1200°C for 2 h in a N2 atmosphere, heated at 2°C / min, and annealed at 1300°C for 4 h to obtain SiC / C nanofibers with rough surfaces.

[0099] See also Figure 1 It can be seen that the nanofibers maintain a one-dimensional morphology, and due to the lack of the introduction of Zn salt, no rough structure appears in the SiC / C nanofibers.

[0100] See also Figure 2 , it can be seen that the SiC / C nanofibers generated after adding zinc acetylacetonate not only maintain the 1D structure, but also have a rough surface structure.

[0101] See also Figure 3 It can be seen that after adding zinc acetylacetonate, amorphous SiC is generated, the diffraction peak of SiC disappears, and no obvious diffraction peak of Zn appears.

[0102] See also Figure 4 , it can be seen that the optimal reflection loss value of the nanofibers generated by adding zinc acetylacetonate is significantly improved.

[0103] See also Figure 5 , it can be seen that the real and imaginary parts of the dielectric constant of the roughened SiC / C nanocomposite fibers generated by adding zinc acetylacetonate are significantly improved.

[0104] See also Figure 6 It can be seen that the effective absorption width of the nanofibers with the addition of zinc acetylacetonate is significantly improved, and full coverage of the Ku and X bands and most of the C band can be achieved at different thicknesses.

[0105] In summary, the present invention discloses a roughened SiC / C nanocomposite fiber, its preparation method, and application. Using PCS as the silicon carbide source and the selective addition of zinc acetylacetonate, the fiber maintains its 1D fiber structure while simultaneously producing a roughened SiC / C nanocomposite fiber. This improves both the real and imaginary dielectric constants and introduces multiple loss mechanisms to achieve optimal impedance matching and electromagnetic loss. Using electrospinning equipment, one-dimensional SiC / C nanocomposite fibers are directly prepared, combining the advantages of both the material and the nanostructure. This simple process yields a high-performance microwave absorber.

[0106] The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and a separate point value, and the separate point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered as specifically disclosed in this article. Hereinafter, in principle, each technical solution can be combined with each other to obtain a new technical solution, which should also be considered as specifically disclosed in this article.

[0107] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the same. Although the present invention has been described in detail with reference to the above embodiments, a person skilled in the art may still modify or make equivalent substitutions to the specific implementations of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the scope of protection of the claims of the present invention to be approved.

Claims

1. A method for preparing a rough-surfaced SiC / C nanocomposite fiber, characterized in that: The following steps are involved: Add polycarbosilane and zinc acetylacetonate to tetrahydrofuran and dissolve them to obtain solution A. Add polyvinyl pyrrolidone to nitrogen-nitrogen dimethylformamide to obtain solution B. Continue stirring solution A and solution B until they are uniform. The mass volume ratio of the polycarbosilane, zinc acetylacetonate, and tetrahydrofuran is (0.5-1.0) g: (0.1-0.2) g: (4-8) mL; the mass volume ratio of the polyvinyl pyrrolidone and nitrogen-nitrogen dimethylformamide is (0.5-1.0) g: (2-4) mL. Adding the uniform solution A to the uniform solution B and mixing them evenly to obtain a spinning solution; According to the preset spinning conditions, the spinning solution is used to spin the precursor fiber; performing a pre-oxidation treatment on the precursor fiber to obtain a pre-oxidized fiber; The pre-oxidized fiber is sintered in a N2 atmosphere and annealed to obtain a SiC / C nanocomposite fiber with a rough surface; the sintering temperature is 1100-1200°C and the time is 2-3 hours; the annealing treatment has a heating rate of 2-5°C / min, a temperature of 1200-1300°C and a time of 2-4 hours.

2. The method for preparing a rough-surfaced SiC / C nanocomposite fiber according to claim 1, characterized in that: The preset spinning conditions include: The spinning speed is 0.1~0.4mm / min, the voltage is 15~20kv, the distance between the collecting drum and the spinneret is 15~20cm, and the rotation speed is 80~100r / min.

3. The method for preparing a rough-surfaced SiC / C nanocomposite fiber according to claim 1, characterized in that: The temperature of the pre-oxidation treatment is 100-200° C., and the time is 2-4 hours.

4. The method for preparing a rough-surfaced SiC / C nanocomposite fiber according to claim 1, characterized in that: The stirring time for continuously stirring solution A and solution B until they are uniform is 0.5 to 1.0 h.

5. The method for preparing a rough-surfaced SiC / C nanocomposite fiber according to claim 1, characterized in that: The solution A in a uniform state is added to the solution B in a uniform state and mixed evenly to obtain a spinning solution, specifically: The homogeneous solution A is added to the homogeneous solution B, and the mixture is magnetically stirred for 12 to 24 hours to obtain a spinning solution.

6. A SiC / C nanocomposite fiber with rough surface prepared according to the preparation method according to any one of claims 1 to 5.

7. Application of the rough surface SiC / C nanocomposite fiber according to claim 6 in the field of electromagnetic wave absorption.

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