ZrB2-SiC hollow rod composite material, preparation method and application

Abstract

The invention belongs to the technical field of electromagnetic wave-absorbing materials, and discloses a ZrB2-SiC hollow rod composite material, a preparation method and application, and the preparation method comprises the following steps: preparing a NaCl-containing ZrB2-SiC precursor by adopting a molten salt assisted sol-gel method, and carrying out carbon thermal reduction treatment on the precursor to obtain the ZrB2-SiC composite material, and enabling the ZrB2-SiC composite material to have a cylindrical hollow rod-shaped structure. According to the ZrB2-SiC hollow rod composite material and the preparation method thereof disclosed by the invention, through synergistic improvement of a preparation process, components and a ratio, the prepared ZrB2-SiC hollow rod composite material has a unique cylindrical hollow rod-shaped structure, so that the ZrB2-SiC hollow rod composite material has excellent normal-temperature and high-temperature electromagnetic wave-absorbing performance and can meet electromagnetic protection wave-absorbing requirements in different temperature environments; the method can better cope with complex and changeable electromagnetic interference environments, and is widely applied to the field of normal-temperature and high-temperature electromagnetic protection.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetic wave absorbing materials, and particularly relates to a ZrB2-SiC hollow rod composite material, a preparation method and an application thereof. Background Art

[0002] The rapid development of electrical equipment and electronic technology has significantly improved productivity and promoted social progress. However, electromagnetic interference and electromagnetic field pollution pose hazards to human health. To solve this problem, various types of electromagnetic wave absorbing materials have been invented.

[0003] For example, CN119371832A discloses an electromagnetic wave absorbing material and a preparation method thereof, which composes a hydroxyl iron powder magnetic metal material and a methyl vinyl silicone rubber polymer material to prepare a material with excellent weather resistance and room temperature wave absorption performance; CN119383941A discloses a composite wave absorbing material, a preparation method and an application thereof. In this patent, metal oxide raw materials are mixed by solid phase and then calcined, and a high-entropy iron alloy composite wave absorbing material is obtained after high-temperature annealing in a reducing atmosphere; CN119653754A discloses a novel resin-based silicon carbide-graphite-nickel composite wave absorbing material and a preparation method thereof. After secondary curing of graphite powder, silicon carbide powder, mullite powder and phenolic resin liquid, a nickel powder-containing epoxy resin liquid is impregnated into a porous graphite preform by a vacuum pressure impregnation technique; CN119263223A discloses a Fe 2.25 Te2@graphene electromagnetic wave absorbing material, a preparation method and an application thereof. First, tellurium is melted, and then iron oxide powder, molten salt and graphene oxide are fully reacted by a molten salt-assisted chemical vapor deposition technique to obtain a wave absorbing material. However, graphite carbon materials, magnetic metal materials and metal oxides have poor corrosion resistance and low oxidation resistance, and magnetic metal materials may lose magnetism at a certain temperature, which limits their application in electromagnetic wave absorption in harsh environments.

[0004] The electromagnetic wave absorbing materials provided in the above prior art all have deficiencies such as complex preparation processes, high costs and poor environmental adaptability, and cannot adapt to the efficient absorption of electromagnetic waves in a variety of different temperature environments, nor can they cope with complex and changeable electromagnetic interference environments. Summary of the Invention

[0005] The object of the present invention is to address the above deficiencies of the prior art. Through the collaborative improvement of components and preparation methods, a ZrB2-SiC hollow rod composite material, a preparation method, and an application with a simple process, low cost, and excellent performance are provided. The ZrB2-SiC hollow rod composite material is prepared by a molten salt-assisted sol-gel method and a carbothermal reduction method, and its microstructure is constructed, so that the obtained ZrB2-SiC hollow rod composite material has a unique cylindrical hollow rod structure, thereby possessing excellent electromagnetic wave absorption performance at normal and high temperatures, meeting the electromagnetic protection and absorption requirements in different temperature environments, and better coping with complex and changeable electromagnetic interference environments.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A preparation method of a ZrB2-SiC hollow rod composite material, which first prepares a ZrB2-SiC precursor containing NaCl by a molten salt-assisted sol-gel method, and then performs carbothermal reduction treatment on the precursor to obtain a ZrB2-SiC composite material with a cylindrical hollow rod structure. It includes the following steps: S1. Dissolve zirconium oxychloride and sucrose in deionized water at 80 °C, and mark the obtained solution as solution A; S2. Dissolve sodium borate in deionized water at 80 °C, and mark it as solution B; S3. Drop solution B into solution A, continuously heat and stir for 30-60 min to form a sol, and then age at 25 °C for 12-18 h to form a gel; S4. After drying the obtained gel at 110 °C, grind it into powder, then add silicon powder or silicon-based compound and mix and stir for 30 min, and dry at 80 °C to obtain a precursor of the ZrB2-SiC hollow rod composite material containing NaCl; S5. Put the precursor powder into a graphite crucible, and under argon protection, perform segmented heat treatment on the precursor powder. First, heat-treat at 1300 °C for 1-3 h, and then continue to heat-treat at 1400 °C - 1600 °C for 2-4 h to obtain the ZrB2-SiC hollow rod composite material.

[0007] A ZrB2-SiC hollow rod composite material, which is prepared by the described method and has a cylindrical hollow rod structure.

[0008] An application of a ZrB2-SiC hollow rod composite material in electromagnetic protection at normal and high temperatures.

[0009] Compared with the prior art, the present invention has the following outstanding advantages: 1. The present invention obtains a ZrB2-SiC composite material with a hollow rod structure by synergistically improving the preparation process, components and ratios. The preparation method can also further prepare ZrB2-SiC hollow rod composite materials of different lengths and thicknesses by changing the type of silicon source added, so that it has high-efficiency electromagnetic wave absorption performance under normal temperature and high temperature environment.

[0010] 2. The ZrB2-SiC composite material provided by the present invention is an organic combination and structural reconstruction of ZrB2 and SiC ceramic materials, so that the two are combined as a dielectric loss-type absorption material as a whole, so that it has excellent high-temperature stability and corrosion resistance, and can be used for electromagnetic wave absorption in harsh environments.

[0011] 3. The preparation method provided by the present invention combines ZrB2 and SiC organically through a simple molten salt-assisted sol-gel method and a carbon thermal reduction method to prepare a ZrB2-SiC composite material. By controlling the components, ratios and process conditions, the prepared ZrB2-SiC composite material has a unique hollow rod structure, which plays an important role in the absorption and multiple scattering of electromagnetic waves. This structure can significantly improve its electromagnetic wave absorption performance at room temperature and high temperature.

[0012] 4. The ZrB2-SiC composite material provided by the present invention, wherein SiC serves as a low dielectric material, can effectively reduce the excessively high dielectric constant of ZrB2 and improve the impedance matching of the ZrB2-SiC composite material. Combined with the unique hollow rod structure, the ZrB2-SiC composite material has excellent room temperature and high temperature electromagnetic absorption performance, can meet the electromagnetic protection absorption in different temperature environments, can perform efficient electromagnetic absorption in a variety of different temperature environments, and has a wide range of uses. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematic diagram of the steps of the preparation method of the ZrB2-SiC hollow rod composite material in an embodiment of the present invention; Figure 2 This is a SEM image of the ZrB2-SiC hollow rod composite material in Example 1 of the present invention; Figure 3 TEM image of the ZrB2-SiC hollow rod composite material in Example 1 of the present invention; Figure 4 is the XRD spectrum of the ZrB2-SiC hollow rod composite material in Example 1 of the present invention; Figure 5 The dielectric constant diagrams of Example 1 and Comparative Examples 1 and 2 of the present invention; Figure 6 The impedance matching diagrams of Example 1 and Comparative Examples 1 and 2 of the present invention; Figure 7 SEM image of the ZrB2-SiC hollow rod composite material in Example 2 of the present invention; Figure 8 SEM image of the ZrB2-SiC hollow rod composite material in Example 3 of the present invention; Figure 9 SEM image of the ZrB2-SiC hollow rod composite material in Example 4 of the present invention. Detailed implementation manners

[0014] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be noted that what is described is only a part of the embodiments of the present invention, rather than all the embodiments, and these embodiments shall not be used to interpret the limitation of the scope of protection of the claims of the present application. Based on the embodiments of the present invention, all other changes or modifications obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the claims of the present application.

[0015] In each embodiment of the present invention, unless otherwise specified, all raw material components are commercially available products well-known to those skilled in the art.

[0016] Basic embodiment Refer to Figure 1 , a preparation method of a ZrB2-SiC hollow rod composite material provided in this embodiment is to first prepare a ZrB2-SiC precursor containing NaCl by a molten salt-assisted sol-gel method, and then perform a carbothermal reduction treatment on the precursor to obtain a ZrB2-SiC composite material with a cylindrical hollow rod structure, which specifically includes the following steps: S1. Dissolve zirconyl chloride and sucrose in deionized water at 80 °C, and mark the obtained solution as solution A; S2. Dissolve sodium borate in deionized water at 80 °C, and mark it as solution B; S3. Drop solution B into solution A, continuously heat and stir for 30 - 60 min to form a sol, and then age it at 25 °C for 12 - 18 h to form a gel; S4. After drying the obtained gel at 110 °C, grind it into powder, then add silicon powder or silicon-based compound and mix and stir for 30 min, and dry it at 80 °C to obtain a precursor of the ZrB2-SiC hollow rod composite material containing NaCl; S5. Put the precursor powder into a graphite crucible, and under the protection of argon, perform segmented heat treatment on the precursor powder. First, heat-treat it at 1300 °C for 1 - 3 h, and then continue to heat-treat it at 1400 °C - 1600 °C for 2 - 4 h to obtain a ZrB2-SiC hollow rod composite material.

[0017] A ZrB2-SiC hollow rod composite material, which is prepared by the method described above, has a cylindrical hollow rod structure.

[0018] Application of a ZrB2-SiC hollow rod composite material in electromagnetic protection at normal and high temperatures.

[0019] During the heat treatment process, under the combined action of molten salt assistance and carbothermal reduction, ZrB2 nanosheets form a hollow rod structure, and Si and C on the surface of ZrB2 react during the carbothermal reduction of ZrB2 to form SiC particles. The SiC particles adhere to the surface and the inner hollow layer of the ZrB2 hollow rod, promoting multiple scattering of electromagnetic waves and interfacial polarization.

[0020] Next, some specific embodiments of the present invention will be used to describe the technical solutions in the present invention more clearly and completely. Obviously, the described embodiments are only some of the embodiments in the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative work shall fall within the scope of protection of the present invention.

[0021] Example 1 See Figures 2 - 6 , on the basis of the basic embodiment, the preparation method of the ZrB2-SiC hollow rod composite material provided in this embodiment, the specifically selected components, ratios and process conditions are as follows: Zirconium oxychloride, sucrose, and sodium borate are added by the molten salt-assisted sol-gel method according to a molar ratio of Zr:C:B = 1:4:8.

[0022] The specific steps are as follows: First, zirconium oxychloride and sucrose are stirred and dissolved in deionized water at 80 °C, and the resulting solution is labeled as solution A; then sodium borate is stirred and dissolved in deionized water at 80 °C, labeled as solution B. Second, solution B is added dropwise to solution A, and continuous heating and stirring are carried out for 45 min to form a sol. Then, it is aged at 25 °C for 15 h to form a gel. The obtained gel is dried at 110 °C, ground into powder after drying, and then silicon powder is added and stirred for 30 min, and dried at 80 °C to obtain a precursor of the ZrB2-SiC hollow rod composite material containing NaCl.

[0023] Finally, the precursor powder is placed in a graphite crucible, and under argon protection, the precursor powder is subjected to segmented heat treatment, first heat-treated at 1300 °C for 2 h, and then continued to be heat-treated at 1500 °C for 2 h. As Figure 2 can be seen, the average length of the prepared sample is about 6 μm, and the thickness is 2 μm.

[0024] As Figure 3As can be seen from the figure: The ZrB2-SiC composite material prepared in the embodiment of the present invention has a unique hollow rod structure. More interfaces increase the interface polarization and the reflection and scattering of electromagnetic waves, thereby improving the wave absorption performance.

[0025] It can be seen from Figure 4 that: In the ZrB2-SiC composite material prepared in the embodiment of the present invention, hexagonal ZrB2 and β-SiC are contained.

[0026] Example 2 Refer to Figure 7 , on the basis of the basic embodiment, the preparation method of the ZrB2-SiC hollow rod composite material provided in this embodiment, the specifically selected components, ratios and process conditions are: By the molten salt-assisted sol-gel method, zirconium oxychloride, sucrose, and sodium borate are added according to the molar ratio of Zr:C:B = 1:4:8. Subsequently, tetraethyl orthosilicate accounting for 6 wt% of the total mass of the gel is added and stirring is continued until drying to obtain a precursor of the ZrB2-SiC hollow rod composite material containing NaCl. The specific experimental steps are the same as those in Example 1. It can be seen from Figure 7 that the average length of the prepared sample is about 5.8 μm and the thickness is 2.3 μm.

[0027] Example 3 Refer to Figure 8 , on the basis of the basic embodiment, the preparation method of the ZrB2-SiC hollow rod composite material provided in this embodiment, the specifically selected components, ratios and process conditions are: By the molten salt-assisted sol-gel method, zirconium oxychloride, sucrose, and sodium borate are added according to the molar ratio of Zr:C:B = 1:4:8. Subsequently, polysiloxane accounting for 6 wt% of the total mass of the gel is added and stirring is continued until drying to obtain a precursor of the ZrB2-SiC hollow rod composite material containing NaCl. The specific experimental steps are the same as those in Example 1. It can be seen from Figure 8 that the average length of the sample prepared in this embodiment is about 5.6 μm and the thickness is 2.6 μm.

[0028] Example 4 Refer to Figure 9 , on the basis of the basic embodiment, the preparation method of the ZrB2-SiC hollow rod composite material provided in this embodiment, the specifically selected components, ratios and process conditions are: By the molten salt-assisted sol-gel method, zirconium oxychloride, sucrose, and sodium borate are added according to the molar ratio of Zr:C:B = 1:4:8. Subsequently, polycarbosilane accounting for 6 wt% of the total mass of the gel is added and stirring is continued until drying to obtain a precursor of the ZrB2-SiC hollow rod composite material containing NaCl. The specific experimental steps are the same as those in Example 1. It can be seen from Figure 9It can be seen that the average length of the prepared sample is about 5.2 μm, and the thickness is 3 μm.

[0029] Comparative Example 1 Commercial ZrB2 particulate powder was used as the electromagnetic wave absorption control group for electromagnetic wave absorption performance testing.

[0030] Comparative Example 2 Commercial SiC particulate powder was used as the electromagnetic wave absorption control group for electromagnetic wave absorption performance testing.

[0031] The materials of Examples 1-4 and Comparative Examples 1-2 were subjected to electromagnetic wave absorption tests under normal temperature and high temperature environments. The coaxial method was used to test the electromagnetic wave absorption performance of the samples. Preparation of electromagnetic wave absorption samples: Paraffin itself has no wave absorption effect and can be used as a wave transmitting agent and a molding agent. The materials were prepared into ring-shaped wave absorption samples for convenient use in coaxial method testing. Paraffin was uniformly mixed with the materials of Examples 1-4 and Comparative Examples 1-2 at a mass ratio of 1:4 to prepare microwave absorption samples. First, paraffin was placed in a glass container, and 0.7 mL of cyclohexane was added to dissolve the paraffin. After the paraffin was completely dissolved under ultrasonic conditions at 60 °C, the corresponding powdered material was added and ultrasonicated at 80 °C until the cyclohexane completely evaporated. The solid in the sample was transferred to a mold and pressed into a concentric ring with an inner diameter of 3.04 mm, an outer diameter of 7 mm, and a thickness of about 2 mm under a pressure of 10 MPa.

[0032] The comparison results of the electromagnetic wave absorption performance parameters of the materials of each example-comparative example at 25 °C are shown in Table 1; the comparison results of the wave absorption performance parameters of different example-comparative example electromagnetic materials at 900 °C are shown in Table 2.

[0033] Table 1

[0034] Table 2

[0035] Figure 5 It is a schematic diagram of the dielectric constant of Example 1, Comparative Example 1, and 2.

[0036] Figure 6 is a graph of impedance matching (Z). In the figure, (a) is Example 1, (b) is Comparative Example 1, and (c) is Comparative Example 2.

[0037] See Appendix Figures 5 - 6, and Tables 1 - 2, where the smaller the reflection loss (RL), the better the electromagnetic wave absorption effect. When the reflection loss is less than -10 dB, 90% of the incident electromagnetic waves can be absorbed and converted into heat energy. The frequency range with a reflection loss less than -10 dB is the effective absorption bandwidth, and the effective absorption bandwidth determines the effective working performance range of the wave-absorbing material. The wider the bandwidth, the larger the effective use range. As shown in Tables 1 and 2, the ZrB2 - SiC hollow rod composite material prepared by the present invention has excellent wave-absorbing properties at room temperature and high temperature and a relatively wide effective absorption bandwidth. The material prepared in Example 1 has a minimum reflection loss of -61.73 dB at a thickness of 3.44 mm in a 25 °C room temperature environment, and at the same time, the effective absorption bandwidth at a thickness of 1.34 mm reaches 3.72 GHz, showing very excellent wave-absorbing properties. And in a 900 °C high temperature environment, the sample has a minimum reflection loss of -31.64 dB at a thickness of 1.58 mm, and at the same time, the effective absorption bandwidth at a thickness of 2.45 mm reaches 2.34 GHz, still showing excellent wave-absorbing properties. Compared with the commercial ZrB2 and SiC in Comparative Examples 1 - 2, the ZrB2 - SiC hollow rod composite material has more excellent wave-absorbing properties at room temperature and high temperature. This is because the interface effect of the hollow rod structure promotes the multiple scattering and interface polarization of electromagnetic waves, and Figure 5 and Figure 6 also proves that the ZrB2 - SiC hollow rod composite material has excellent spatial impedance matching (Z).

[0038] In the above embodiments of the present invention, the key is to prepare a ZrB2 - SiC precursor containing NaCl by a molten salt-assisted sol-gel method, and the precursor is subjected to carbothermal reduction treatment to obtain ZrB2 - SiC hollow rods. As a low-dielectric material, SiC can effectively reduce the too-high dielectric constant of ZrB2 and improve the impedance matching of the ZrB2 - SiC composite material. The unique hollow rod structure enables the ZrB2 - SiC composite material to have excellent wave-absorbing properties at room temperature and high temperature to meet electromagnetic protection and wave absorption in different temperature environments. In addition, the ZrB2 - SiC hollow rod composite material prepared by the present invention not only has the characteristics of low loading, excellent wave-absorbing properties at room temperature and high temperature, and an effective absorption bandwidth, but also has a simple preparation method and is easy to operate. By changing the types of silicon-based compounds, the controllable growth of the length and thickness of the hollow rod composite material can be realized to meet the requirements of actual production, and it is expected to play an application value in the field of electromagnetic interference protection of equipment.

[0039] It should be particularly noted that the components, ratios, and process parameters adopted in the above specific embodiments of the present invention are only examples. Other different implementation schemes obtained by specific selection within the scope recorded in the basic embodiments of the present invention can all achieve the technical effects recorded in the present invention, so the present invention will not list them one by one.

[0040] As described above, it is only the preferred embodiment of the present invention, and it does not impose any form of limitation on the present invention. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment with equivalent changes. All equivalent changes made according to the components, ratios and processes of the present invention shall be covered within the protection scope of the present invention.

Claims

1. A preparation method of a ZrB2-SiC hollow rod composite material, characterized in that, First, a molten salt-assisted sol-gel method is used to prepare a ZrB2-SiC precursor containing NaCl. After carbon thermal reduction treatment of the precursor, a ZrB2-SiC composite material is obtained, which has a cylindrical hollow rod structure.

2. The preparation method of the ZrB2-SiC hollow rod composite material according to claim 1, characterized in that, It includes the following steps: S1. Dissolve zirconium oxychloride and sucrose in deionized water at 80 °C, and mark the resulting solution as solution A; S2. Dissolve sodium borate in deionized water at 80 °C, and mark it as solution B; S3. Drop solution B into solution A, continuously heat and stir for 30 - 60 min to form a sol, and then age it at 25 °C for 12 - 18 h to form a gel; S4. After drying the obtained gel at 110 °C, grind it into powder, then add silicon powder or a silicon-based compound and mix and stir for 30 min, and dry it at 80 °C to obtain a precursor of a ZrB2-SiC hollow rod composite material containing NaCl; S5. Put the precursor powder into a graphite crucible, and under argon protection, perform segmented heat treatment on the precursor powder. First, heat-treat it at 1300 °C for 1 - 3 h, and then continue to heat-treat it at 1300 °C - 1600 °C for 2 - 4 h to obtain a ZrB2-SiC hollow rod composite material.

3. The preparation method of the ZrB2-SiC hollow rod composite material according to claim 2, characterized in that, In steps S1 - S2, a molten salt-assisted sol-gel method is used to add zirconium oxychloride, sucrose, and sodium borate according to a molar ratio of Zr:C:B = 1:4:

8.

4. The preparation method of the ZrB2-SiC hollow rod composite material according to claim 2, characterized in that, The silicon-based compound is a mixture of one or more of tetraethyl orthosilicate, polysiloxane, and polycarbosilane.

5. The preparation method of the ZrB2-SiC hollow rod composite material according to claim 2, characterized in that, By adding different types of silicon sources in step S4, ZrB2-SiC hollow rod composite materials with different lengths and thicknesses can be correspondingly prepared.

6. The preparation method of the ZrB2-SiC hollow rod composite material according to claim 2, wherein, The addition amount of the silicon powder or silicon-based compound in step S4 is 3 wt% - 9 wt%.

7. A ZrB2-SiC hollow rod composite material, which is prepared by the method described in any one of claims 1 - 4, and has a cylindrical hollow rod structure.

8. An application of a ZrB2-SiC hollow rod composite material in electromagnetic protection at normal and high temperatures.

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