Optical fiber-like nanofiber wave-absorbing material and preparation method thereof

Abstract

The application provides a kind of optical fiber-like nanofiber wave-absorbing material, comprising ZrC / C fiber and ZrO2 oxide layer coated on the surface of ZrC / C fiber, which overcomes the defects of conventional wave-absorbing material and has broad application prospect. The application also provides a preparation method of optical fiber-like nanofiber wave-absorbing material, which uses in-situ oxidation method combined with electrospinning to prepare ZrO2 grain oxide layer on the surface of ZrC / C fiber on the basis of retaining fiber structure. The method is simple, easy to operate and convenient for large-scale production.

Description

TECHNICAL FIELD

[0001] The application relates to a wave-absorbing material, in particular to a kind of optical fiber-like nanofiber wave-absorbing material and a preparation method thereof. BACKGROUND

[0002] Under the application of digital information technology, modern electronic information technology develops rapidly, and everything is interconnected. Information interconnection brings convenience, but electromagnetic radiation generated by electronic devices is widespread around the world. Excessive electromagnetic radiation can interfere with precision instruments and affect signal transmission. In the military field, radar detection and weapon guidance technology have progressed, and weapon equipment is easy to be detected, tracked and attacked by the enemy. Electromagnetic wave absorbing materials can effectively solve electromagnetic radiation pollution and be used for military counter-reconnaissance to improve the concealment of weapon equipment. Therefore, wave-absorbing materials with the characteristics of "wide, thin, strong and light" have a great demand gap for application in high-tech and extreme environments.

[0003] Currently commonly used wave-absorbing materials mainly include conductive polymers, ferrites, carbon composites and three-dimensional heterogeneous structure materials. However, most of the wave-absorbing materials are difficult to be applied in high-temperature harsh environments due to their own characteristics. For example, traditional electromagnetic shielding materials such as ferrite have serious performance degradation at Curie temperature, conductive polymers and carbon composites have poor thermal stability and are easy to be oxidized. In addition, the problems such as large density of traditional wave-absorbing materials and dependence on space structure of three-dimensional structure materials will limit the application of materials to some extent.

[0004] In order to solve the above problems, people have been seeking an ideal technical solution. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings of the prior art and provide an optical fiber-like nanofiber wave-absorbing material and a preparation method thereof.

[0006] Specifically, ZrC ceramic in transition metal carbide (TMC) is a typical superhigh-temperature ceramic, which has high melting point, oxidation resistance and high-temperature stability and is widely used in the hot end of aircraft. From another point of view, it also has the potential to become a high-temperature wave-absorbing material due to its high electrical conductivity. Therefore, ZrC / C fibers prepared from ZrC can have a network conductive structure while having the high-temperature stability and oxidation resistance of ZrC. However, the high electrical conductivity of ZrC itself also causes serious mismatch of the surface impedance of the fiber, resulting in strong reflection of electromagnetic waves.

[0007] The present application provides a way of in-situ oxidation of ZrO2 grain layer on the surface of ZrC / C fiber to reduce the electrical conductivity of the fiber, thereby improving the surface impedance matching, enhancing the interface polarization and improving the electromagnetic wave absorption performance of the fiber.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A fiber-like nanofiber absorbing material includes ZrC / C fibers and a ZrO2 oxide layer coated on the surface of the ZrC / C fibers.

[0010] ZrC / C fibers are interconnected to form a spatial network structure, and ZrO2 consists of round or elliptical grains grown on the fiber surface.

[0011] A method for preparing the aforementioned fiber-like nanofiber absorbing material includes the following steps:

[0012] S1: Prepare a spinning solution containing zirconium and carbon; the molar ratio of zirconium to carbon is 1:(3-7).

[0013] S2: Electrospinning yields precursor fiber membranes;

[0014] S3: The precursor fiber membrane is dried, cured, and carbonized to obtain ZrC / C fibers;

[0015] S4: ZrC / C fibers are oxidized to obtain ZrC / C fiber materials with a uniform ZrO2 oxide layer.

[0016] Curing is carried out by holding at 200–350℃ for 1–2 hours; carbonization is carried out by holding at 1500–1600℃ for 1–3 hours under an argon atmosphere. The curing and carbonization processes are carried out under an argon atmosphere.

[0017] In step S4, oxidation is carried out by heating at 500–700°C for 3–5 minutes in an air atmosphere.

[0018] The spinning solution includes a carbon source and a zirconium source; the carbon source includes carbon-containing organic matter, high molecular polymer and organic solvent in a mass ratio of (8-10):10:(70-100); the zirconium source includes zirconium organic salt, anhydrous ethanol and stabilizer in a volume ratio of 4:(2-5):1.

[0019] The carbon-containing organic matter is glucose, sucrose, or cellulose; the high molecular polymer is polystyrene, polyvinyl alcohol, or polyvinylpyrrolidone; and the organic solvent is anhydrous ethanol or N,N-dimethylformamide.

[0020] The zirconium-containing organic salt is zirconium n-propoxide or zirconium acetylacetonate; the stabilizer is acetylacetonate, acetic acid, or acetone.

[0021] In step S2, the electrospinning conditions are as follows: temperature: 20-25℃, humidity: 40-60%, distance between roller and spinning solution: 10-15 cm, spinning rate: 0.01-0.1 mL / min, spinning voltage: +8.0-+11.0 KV, -1.0--0.5 KV.

[0022] In step S3, the precursor fiber membrane is vacuum dried at 50-80℃ for 10-16 h, and then cured.

[0023] This invention possesses significant substantive features and substantial advancements compared to existing technologies. Specifically, it provides a fiber-optic nanofiber absorbing material comprising ZrC / C fibers and a ZrO2 oxide layer coating the surface of the ZrC / C fibers. The ZrC / C fibers are interconnected to form a spatial network structure, significantly improving the conductivity of the composite material. Furthermore, the ZrO2 grains grown on the surface of the ZrC / C fibers introduce ZrC / ZrO2 and ZrO2 / C interface layers into the fibers. The presence of numerous interfaces allows the material to generate more polarization phenomena under electromagnetic field influence, adjusting the electromagnetic parameters of the ZrC fibers and optimizing the impedance matching between the fibers and free space, thereby increasing interface polarization loss. Moreover, the ZrO2 grains can guide more electromagnetic waves into the fiber interior for absorption, rather than reflection from the fiber surface. The synergistic effect of multiple mechanisms, including interface polarization, conductivity loss, and scattering, enhances the fiber's attenuation capability for electromagnetic waves. Meanwhile, this invention also provides a method for preparing fiber-like nanofiber absorbing materials. By combining in-situ oxidation with electrospinning, a ZrO2 grain oxide layer is prepared on the surface of ZrC / C fibers while retaining the fiber structure. This method is simple, easy to operate, and convenient for large-scale production. Attached Figure Description

[0024] Figure 1 This is a SEM image of the precursor ZrC fiber in Example 1 of the present invention;

[0025] Figure 2 This is a SEM image of the carbonized ZrC / C fibers in Example 1 of the present invention;

[0026] Figure 3 This is a low-magnification SEM image of the fiber-like nanofiber absorbing material in Embodiment 1 of the present invention;

[0027] Figure 4 This is a high-magnification SEM image of the fiber-like nanofiber absorbing material in Embodiment 1 of the present invention;

[0028] Figure 5 The image shows the XRD pattern of the fiber-like nanofiber absorbing material in Embodiment 1 of the present invention.

[0029] Figure 6 This is a diagram showing the electromagnetic wave reflection loss of the fiber-like nanofiber absorbing material in Embodiment 1 of the present invention in the 2-18 GHz band. Detailed Implementation

[0030] The technical solution of the present invention will be further described in detail below through specific embodiments. It should be noted that the various devices involved in the following embodiments are all commercially available devices of the prior art, and similar devices can be used as needed. Example

[0031] This embodiment provides a type of optical fiber nanofiber absorbing material, including ZrC / C fibers and a ZrO2 oxide layer coated on the surface of the ZrC / C fibers; the ZrC / C fibers are interconnected to form a spatial network structure, and the ZrO2 is a circular or elliptical grain grown on the surface of the fibers.

[0032] This type of optical fiber nanofiber absorbing material can be prepared through the following steps:

[0033] 1. Take carbon-containing organic matter, high molecular polymer and organic solvent in a mass ratio of (8~10):10:(70~100), heat and stir at 70-90℃ to dissolve them to obtain carbon source;

[0034] 2. Mix the zirconium-containing organic salt, anhydrous ethanol and stabilizer in a volume ratio of 4:(2-5):1 and stir at room temperature for 2 hours. The purpose is to polymerize the zirconium-containing organic salt to obtain a stable polymer, which is a zirconium source.

[0035] 3. Mix the carbon source and zirconium source and stir overnight at room temperature to ensure that the two are mixed evenly to obtain a spinning solution;

[0036] IV. Temperature and humidity are controlled between 20 and 25℃ and 40 and 60, respectively. The distance between the roller and the spinning solution is 10 to 15 cm. Electrospinning is carried out at a feed rate of 0.01 to 0.1 mL / min under the conditions of +8.0 KV to +11.0 KV and -1.0 KV to -0.5 KV to obtain precursor fiber membrane.

[0037] 5. Place the above-mentioned precursor fiber membrane in a vacuum drying oven at 50-80°C to remove residual anhydrous ethanol until it is completely dry.

[0038] 6. The dried precursor fiber membrane is laid flat in a carbon crucible, and the fiber membrane is pressed flat with a carbon plate. Then, the carbon crucible is placed in a tube furnace, and argon gas is continuously introduced at a flow rate of 0.16 mL / min for protection. The temperature is raised to 200–350℃ at a certain rate and held for 1–2 h to solidify the fiber and obtain cured fiber. Then, the temperature is raised to 1500–1600℃ at a certain rate and held for 1–3 h before being removed to obtain ZrC / C fiber.

[0039] 7. Place the ZrC / C fiber in a muffle furnace, control the oxidation temperature between 500 and 700°C, and take it out after 3 to 5 minutes of oxidation to obtain ZrC / C fiber coated with ZrO2 layer, which is a fiber-like nanofiber absorbing material.

[0040] Example 1

[0041] This embodiment provides a fiber-optic nanofiber absorbing material, comprising ZrC / C fibers and a ZrO2 oxide layer coating the surface of the ZrC / C fibers. Its XRD pattern is shown in [reference needed]. Figure 5 See appendix Figures 3-4 The ZrC / C fibers are interconnected to form a spatial network structure, and ZrO2 consists of circular or elliptical grains grown on the fiber surface. Electromagnetic parameters were tested using a vector network analyzer, and the minimum reflection loss of the fiber-like nanofiber absorbing material was calculated to be -53.72 dB, with a maximum effective absorption bandwidth of 4.02 GHz, based on the measured dielectric constant.

[0042] This embodiment also provides a method for preparing this type of optical fiber nanofiber absorbing material, which includes the following steps:

[0043] Add 0.86 g of sucrose to a solution prepared with 0.83 g of polyvinylpyrrolidone and 6.4 ml of DMF, and heat at 80 °C for about 2 h to dissolve it to obtain a carbon source; take zirconium propoxide: anhydrous ethanol: acetylacetone = 1.6 ml: 1.2 ml: 0.4 ml, stir at room temperature for 2 h to obtain a zirconium source;

[0044] Carbon source and zirconium source were mixed and stirred overnight at room temperature to obtain electrospinning solution; the electrospinning solution was electrospinned under the conditions of +10 KV, -1.0 KV voltage, 15 cm spinning distance, 0.52 mm spinning inner diameter and 0.01 mL / min spinning speed to obtain precursor fiber membrane.

[0045] The precursor fiber membrane was vacuum dried at 60℃ for 12 h to ensure complete removal of the solvent anhydrous ethanol. The dried precursor fiber membrane was then laid flat in a carbon crucible and pressed flat with a carbon plate. The carbon crucible was then placed in a tube furnace and protected with a continuous argon gas flow of 0.16 mL / min. The temperature was raised to 350℃ and held for 90 min to solidify the fiber. The temperature was then raised to 1500℃ and held for 90 min before being removed to obtain ZrC / C fiber.

[0046] ZrC / C fibers were placed in a carbon crucible, and the crucible was placed in a muffle furnace and oxidized at 550°C for 5 min to obtain the above-mentioned fiber-like nanofiber absorbing material.

[0047] Example 2

[0048] This embodiment provides a type of optical fiber nanofiber absorbing material, including ZrC / C fibers and a ZrO2 oxide layer coated on the surface of the ZrC / C fibers; the ZrC / C fibers are interconnected to form a spatial network structure, and the ZrO2 is a circular or elliptical grain grown on the surface of the fibers.

[0049] This type of optical fiber nanofiber absorbing material can be prepared through the following steps:

[0050] Add 0.85 g of glucose to a solution prepared by 0.9 g of polyacrylonitrile and 8.58 ml of DMF, and heat at 80 °C for about 2 h to dissolve it to obtain a carbon source; take zirconium propoxide: anhydrous ethanol: acetylacetone = 1.6 ml: 1.2 ml: 0.4 ml, stir at room temperature for 2 h to obtain a zirconium source.

[0051] Carbon source and zirconium source were mixed and stirred overnight at room temperature to obtain electrospinning solution; the electrospinning solution was electrospinned under the conditions of +11.5 KV, -0.8 KV voltage, 15 cm spinning distance, 0.52 mm spinning inner diameter and 0.01 ml / min spinning speed to obtain precursor fiber membrane.

[0052] The precursor fiber membrane was vacuum dried at 60℃ for 12 h to ensure complete removal of the solvent anhydrous ethanol. The dried precursor fiber membrane was then laid flat in a carbon crucible and pressed flat with a carbon plate. The carbon crucible was then placed in a tube furnace and protected with a continuous flow of argon gas at 0.16 mL / min. The temperature was raised to 300℃ and held for 90 min to solidify the fiber. The temperature was then raised to 1500℃ and held for 90 min before being removed to obtain ZrC / C fiber.

[0053] ZrC / C fibers were placed in a carbon crucible, which was then placed in a muffle furnace and oxidized at 600℃ for 4 min to obtain a fiber-like nanofiber absorbing material.

[0054] Example 3

[0055] This embodiment provides a type of optical fiber nanofiber absorbing material, including ZrC / C fibers and a ZrO2 oxide layer coated on the surface of the ZrC / C fibers; the ZrC / C fibers are interconnected to form a spatial network structure, and the ZrO2 is a circular or elliptical grain grown on the surface of the fibers.

[0056] 0.87 g of cellulose was added to a solution prepared by 0.88 g of polyvinylpyrrolidone and 6.5 ml of DMF, and dissolved by heating at 80 °C for about 2 h to obtain a carbon source; zirconium propoxide: anhydrous ethanol: acetic acid = 1.6 ml: 1.2 ml: 0.4 ml was stirred at room temperature for 2 h to obtain a zirconium source;

[0057] Carbon source and zirconium source were mixed and stirred overnight at room temperature to obtain an electrospinning solution. The electrospinning solution was electrospinned under the conditions of +12.3 KV, -0.8 KV, 15 cm spinning distance, 0.61 mm spinning inner diameter, and 0.015 ml / min spinning speed to obtain a precursor fiber membrane.

[0058] The precursor fiber membrane was vacuum dried at 60℃ for 12 h to ensure complete removal of the solvent anhydrous ethanol. The dried precursor fiber membrane was then laid flat in a carbon crucible and pressed flat with a carbon plate. The carbon crucible was then placed in a tube furnace and protected with a continuous flow of argon gas at 0.16 mL / min. The temperature was raised to 350℃ and held for 90 min to solidify the fiber. The temperature was then raised to 1500℃ and held for 90 min before being removed to obtain ZrC / C fiber.

[0059] ZrC / C fibers were placed in a carbon crucible, and the crucible was placed in a muffle furnace and oxidized at 700℃ for 3 min to obtain a fiber-like nanofiber absorbing material.

[0060] Appearance description

[0061] The precursor fiber membranes obtained in Examples 1 to 3 are all white with a slight yellow tint and have good flexibility; after carbonization, they are black fiber membranes with a certain degree of flexibility. After oxidation treatment, Example 1 appears black and has flexibility, Example 2 appears grayish-black and has a certain degree of flexibility, and Example 3 appears whiteish-gray.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A method for preparing a light-fiber-like nanofiber wave-absorbing material, comprising the following steps: S1: preparing a spinning solution containing zirconium and carbon elements, wherein the molar ratio of the zirconium and carbon elements is 1: (3-7), the spinning solution comprises a carbon source and a zirconium source, the carbon source comprises carbon-containing organic matter, a high-molecular polymer and an organic solvent, the zirconium source comprises a zirconium organic salt, anhydrous ethanol and a stabilizer, the carbon-containing organic matter is glucose, sucrose or cellulose, the high-molecular polymer is polystyrene or polyvinylpyrrolidone, and the zirconium organic salt is zirconium n-propyl alcohol or zirconium acetylacetone; S2: electrospinning to obtain a precursor fiber membrane; S3: drying, curing and carbonizing the precursor fiber membrane to obtain ZrC / C fibers, wherein the curing and carbonizing processes are performed in an argon atmosphere; S4: heating the ZrC / C fibers at 500-700℃ for 3-5 min in an air atmosphere to perform oxidation, thereby obtaining ZrC / C fiber material with a uniform ZrO2 oxidation layer.

2. The method of claim 1, wherein: In step S3, the curing is performed at 200-350℃ for 1-2 h, and the carbonizing is performed at 1500-1600℃ for 1-3 h.

3. The method of claim 1, wherein: The carbon source comprises carbon-containing organic matter, a high-molecular polymer and an organic solvent in a mass ratio of (8-10) :10: (70-100), and the zirconium source comprises a zirconium organic salt, anhydrous ethanol and a stabilizer in a volume ratio of 4: (2-5) :

1.

4. The method of claim 1, wherein: The organic solvent is anhydrous ethanol or N, N-dimethylformamide.

5. The method of claim 1, wherein: The stabilizer is acetylacetone, acetic acid or acetone.

6. The method of claim 1, wherein: In step S2, the electrospinning conditions are as follows: temperature: 20-25℃, humidity: 40-60%, roller shaft to spinning solution distance: 10-15 cm, spinning rate: 0.01-0.1 mL / min, spinning voltage: +8.0 to +11.0 KV, and -1.0 to -0.5 KV.

7. The method of claim 1, wherein: In step S3, the precursor fiber membrane is vacuum dried at 50-80℃ for 10-16 h, and then is subjected to curing treatment.

8. The optical-fiber-like nanofiber wave-absorbing material prepared by the method of any one of claims 1-7, characterized in that: The ZrC / C fiber and the ZrO2 oxidation layer coated on the surface of the ZrC / C fiber. 9.The wave-absorbing material of the optical fiber-like nanofiber according to claim 8, characterized in that: The ZrC / C fibers are connected to each other to form a space net structure, and the ZrO2 is a circular or elliptical grain grown on the surface of the fiber.

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