A high shielding effectiveness heterogeneous structure composite material and its preparation method and application

Abstract

The present invention discloses a high-shielding-effectiveness heterostructured composite material, preparation method, and application thereof, comprising the following steps: S1. Mixing Nb2O5, FeCl3·6H2O, and Na2SO4·10H2O in deionized water in a certain proportion to obtain a uniform solution; S2. Transferring the uniform solution obtained in S1 to a sealed container, heating it at a constant temperature, and then annealing it in an air environment to obtain a precipitate, cooling it to room temperature, and centrifuging and washing it to obtain a NF heterostructured nanocomposite material. The present invention utilizes the above-mentioned high-shielding-effectiveness heterostructured composite material, preparation method, and application thereof, synthesizing the NF heterostructured nanocomposite material via a double hydrothermal method. The synergistic effect of niobium pentoxide and trivalent iron oxide, as well as morphology control, significantly enhances its overall shielding effectiveness, which is of great value in the fields of modern electronics and technology.

Description

Technical Field

[0001] The present invention relates to the technical field of nanocomposite materials, and in particular to a heterogeneous structure composite material with high shielding effectiveness, a preparation method and an application thereof. Background Art

[0002] Radar absorbing materials (RAMs) are gaining increasing recognition as essential components in both tactical and defensive applications. More specifically, RAMs absorb radiation, thereby shielding it, or scatter it, thereby achieving invisibility and avoiding detection. The degree of shielding or scattering is often quantified by shielding effectiveness (SE). Typically, the total shielding effectiveness (SET) of RAMs is defined as their ability to absorb, reflect, and transmit incident radiation. In tactical scenarios, the degree of shielding or scattering is often expressed by radar cross section (RCS).

[0003] In principle, the most effective RAMs should possess both electrical conductivity and magnetic properties. However, excessively high electrical conductivity can unexpectedly enhance reflection-based SE, which is undesirable in RAM applications. Furthermore, in today's technological environment, the rapid expansion of electronic devices and their operation at high frequencies further increase susceptibility to electromagnetic interference (EMI). Consequently, severe performance degradation and failures are common. Therefore, the development of effective EMI shielding materials is urgently needed.

[0004] Traditional shielding solutions often struggle to find the optimal compromise between performance, weight, and flexibility, driving the need for new alternative materials. These materials, such as metal oxide heterostructures, promise to mitigate the limitations of traditional solutions while further enhancing their electromagnetic shielding capabilities.

[0005] In the existing technology, various forms of metal oxide heterostructures have been synthesized, including nanorods (NRs), nanoparticles (NPs), nanospheres, nanofibers and nanobelts. Their synthesis techniques include thermal oxidation, plasma oxidation, sol-gel method, chemical precipitation method, forced hydrolysis method, pulsed laser deposition, chemical vapor deposition, template-assisted method, high-energy ball milling, electrospinning and hydrothermal method. Among them, the hydrothermal method has been proven to be particularly advantageous due to its simple process, low cost and low temperature treatment that helps promote the development of single-crystal oxide nanostructures. With the increasing demand for effective EMI shielding in industries requiring high electromagnetic interference protection, the urgency of finding new shielding materials continues to rise. Summary of the Invention

[0006] The purpose of the present invention is to provide a heterostructured composite material with high shielding effectiveness, as well as a preparation method and application. The NF heterostructured nanocomposite material is synthesized by a double hydrothermal method. The synergistic effect of niobium pentoxide and trivalent iron oxide and morphology control significantly improve its overall shielding effectiveness, which is of great value in the fields of modern electronics and technology.

[0007] To achieve the above object, the present invention provides a method for preparing a heterogeneous structure composite material with high shielding effectiveness, comprising the following steps:

[0008] S1. Mix Nb2O5, FeCl3·6H2O and Na2SO4·10H2O in deionized water in a certain proportion to obtain a uniform solution;

[0009] S2. The uniform solution obtained in S1 is transferred to a sealed container, subjected to constant temperature heating treatment, and then annealed in an air environment to obtain a precipitate, which is cooled to room temperature. After centrifugation and washing, the NF heterostructured nanocomposite material is obtained.

[0010] Preferably, in S1, the mass ratio of the Nb2O5, the FeCl3·6H2O, the Na2SO4·10H2O and the deionized water is 0.05-0.15g:0.01-0.02g:0.05-0.07g:25-35ml.

[0011] Preferably, in S2, the constant temperature heating treatment is specifically:

[0012] Maintain the temperature within the range of 160°C to 200°C for 10 hours to 14 hours.

[0013] Preferably, in S2, the annealing treatment is specifically:

[0014] Annealing is performed at a heating rate of 1°C / min to 3°C / min in a temperature range of 450°C to 550°C for 2h to 4h.

[0015] Preferably, in S2, the washing is performed multiple times using ethanol and deionized water.

[0016] To achieve the above objectives, the present invention also provides a NF heterostructure nanocomposite material.

[0017] To achieve the above objectives, the present invention also provides an application of the NF heterostructure nanocomposite material in capacitors, insulators and other electronic components.

[0018] Preferably, the NF heterostructure nanocomposite material is embedded in a silicone elastomer matrix by mechanical mixing and solution mixing techniques to obtain a sample for electromagnetic shielding.

[0019] Preferably, the method comprises the following steps:

[0020] Step 1: Mixing a polymer matrix and a curing agent in a certain proportion to prepare a silicon solution;

[0021] Step 2: The NF heterostructure nanocomposite material is added to the silicon solution, dispersed and then solidified to obtain a sample.

[0022] Preferably, step 2 is specifically as follows:

[0023] The NF heterostructured nanocomposite was incorporated into the silicon solution and internally mixed at 180 rpm for 30 min to obtain a NF / silicon mixture with particles uniformly dispersed in the silicon matrix. The mixture was then cured at 100°C / min for 25 min to obtain a NF heterostructured nanocomposite / silicone elastomer.

[0024] Therefore, the present invention adopts the above-mentioned heterogeneous structure composite material with high shielding effectiveness, and its preparation method and application, and has the following beneficial effects:

[0025] (1) The present invention utilizes the synergistic effect of Nb2O5 (niobium pentoxide) and α-Fe2O3 (hematite or trivalent iron oxide) to provide better dielectric properties, helping to effectively dissipate energy and achieve ultra-low microwave reflection by effectively absorbing electromagnetic waves, thereby enhancing overall shielding effectiveness. In addition, morphology control can increase the number of interactions between the material surface and electromagnetic radiation, further improving the shielding effect.

[0026] (2) The present invention utilizes Nb2O5 nanoparticles (NPs) as a powerful source of interfacial polarization, while α-Fe2O3 nanorods (NRs) form a large conductive network, enabling electronic conduction hopping between the Nb2O5 NPs. Furthermore, the large voids within the Nb2O5 NPs provide multiple scattering events, further enhancing the dissipation process of electromagnetic waves. By enhancing the effective absorption brought about by these mechanisms and achieving an optimal conductivity to balance conduction loss and reflection loss, a nanocomposite material with superior shielding effect and exceptionally low microwave reflectivity was developed.

[0027] (3) The synergistic effect of the dielectric loss caused by the Nb2O5 nanoparticles of the present invention and the magnetic loss caused by the α-Fe2O3 nanorods ensures that most of the incident electromagnetic energy is slowed down and converted into heat or other non-electromagnetic forms of energy. This dual loss mechanism maximizes energy dissipation through the complementary nature of electrical and magnetic paths, and plays a vital role in the superior electromagnetic interference shielding performance.

[0028] (4) The synergistic effect, dipole polarization, interface polarization, microcapacitance effect and conductive loss between the two metal oxides of the present invention open up broad prospects for further high-performance application research and development, including random access memory (RAM) technology and effective electromagnetic interference shielding solutions, providing a reasonable synthesis route for exploring advanced functional materials and opening up a new research window.

[0029] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 1 is a scanning electron microscope image of a heterogeneous structure composite material with high shielding effectiveness, a preparation method, and an application example of the present invention, wherein (a) is comparative example 1, (b) is comparative example 2, and (c) is example 1;

[0031] Figure 2 1 is a transmission electron micrograph of Example 1 of a heterogeneous structure composite material with high shielding effectiveness of the present invention, wherein (a) is a transmission electron micrograph at 100 nm, and (b) is a transmission electron micrograph at 200 nm;

[0032] Figure 3 The present invention provides a high shielding effectiveness heterogeneous structure composite material and its preparation method and application embodiment of the complex dielectric constant and complex permeability spectrum, wherein (a) is the X-band complex dielectric constant real part spectrum, (b) is the X-band complex dielectric constant imaginary part spectrum, (c) is the X-band complex permeability real part spectrum, (d) is the X-band complex permeability imaginary part spectrum;

[0033] Figure 4 Graph showing frequency dependence of a high shielding effectiveness heterogeneous structure composite material, preparation method, and application example of the present invention, wherein (a) is the dielectric loss tangent and (b) is the magnetic loss tangent;

[0034] Figure 5 1 is a Cole-Cole diagram of an embodiment of a heterogeneous structure composite material with high shielding effectiveness of the present invention, wherein (a) is comparative example 1, (b) is comparative example 2, and (c) is embodiment 1;

[0035] Figure 6 This is a comparison diagram of the frequency dependence of electromagnetic shielding effectiveness (EMI SE) of a heterogeneous structure composite material with high shielding effectiveness, a preparation method and an application embodiment of the present invention. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0037] Unless otherwise defined, technical or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0038] Example 1

[0039] A method for preparing a heterogeneous structure composite material with high shielding effectiveness comprises the following steps:

[0040] S1. Mix 0.1 g of pre-synthesized Nb2O5, 0.016 g of FeCl3·6H2O, and 0.06 g of Na2SO4·10H2O in 30 mL of deionized water to obtain a homogeneous solution.

[0041] S2. The uniform solution obtained in S1 was transferred to a polytetrafluoroethylene-lined reactor, maintained at 180°C for 12 h, and then annealed at 500°C for 3 h in an air environment at a heating rate of 2°C / min to improve the crystallinity of the heterostructure. The precipitate was cooled to room temperature, centrifuged and washed with ethanol and deionized water to obtain NF (Nb2O5NPs@α-Fe2O3NRs) heterostructure nanocomposite material.

[0042] Comparative Example 1

[0043] Preparation of a Nb2O5 NPs heterostructure nanomaterial, specifically:

[0044] 0.1 g of pre-synthesized Nb2O5 was mixed with 30 mL of deionized water to obtain a homogeneous solution, which was then transferred to a polytetrafluoroethylene-lined reactor and maintained at 180°C for 12 h. It was then annealed at 500°C for 3 h in an air environment at a heating rate of 2°C / min to improve the crystallinity of the heterostructure. The precipitate was cooled to room temperature, separated by centrifugation, and washed with ethanol and deionized water to obtain Nb2O5 NPs heterostructured nanomaterials.

[0045] Comparative Example 2

[0046] Preparation of an α-Fe2O3 NRs heterostructure nanomaterial, specifically:

[0047] 0.016 g of FeCl3·6H2O and 0.06 g of Na2SO4·10H2O were mixed in 30 mL of deionized water to obtain a homogeneous solution. The homogeneous solution was transferred to a polytetrafluoroethylene-lined reactor and maintained at 180°C for 12 h. It was then annealed at 500°C for 3 h in an air environment at a heating rate of 2°C / min to improve the crystallinity of the heterostructure. The precipitate was cooled to room temperature, centrifuged, and washed with ethanol and deionized water to obtain α-Fe2O3 NRs heterostructure nanomaterials.

[0048] Experimental testing

[0049] like Figure 1 As shown, Figure 1 Figure (a) shows Nb2O5 nanoparticles with a highly porous structure and aggregated morphology. The porous structure of Nb2O5 nanoparticles provides a large surface area for efficient interaction with electromagnetic waves. The high surface-to-volume ratio facilitates the scattering and absorption of electromagnetic radiation, thereby enhancing shielding effectiveness. Furthermore, the porous nature of these particles can lead to multiple reflections within the material, an ideal property for absorbing electromagnetic waves.

[0050] Figure 1 (b) shows the more compact and angular morphology of the α-Fe2O3 nanorods. These regular geometries indicate that the growth was controlled by the hydrothermal process, and that the parameters were chosen to achieve preferential crystal growth along a specific axis. The α-Fe2O3 nanorods exhibit a compact and ordered structure, which contributes to their anisotropic electromagnetic properties. The directionality of these nanorods can be exploited to tailor the electromagnetic wave propagation path within the shielding material, enabling optimal interaction with the incident electromagnetic wave.

[0051] Figure 1 (c) is a NF heterostructure nanocomposite material. The arrows indicate the interconnected disordered agglomerates connected by extended rod-like structures. The heterostructure formed by Nb2O5 nanoparticles and α-Fe2O3 nanorods shows a morphology in which nanoparticles are uniformly attached to the surface of the nanorods, which can enhance the interfacial interaction between the two phases, thereby improving charge separation and migration. Figure 2 As shown, the interface between α-Fe2O3 nanorods and Nb2O5 nanoparticles exhibits distinct recognition features, indicating good formation of the composite material. This suggests that the current dual hydrothermal synthesis method is effective in uniformly integrating the two materials into a composite form, demonstrating its improved synergistic properties.

[0052] In addition, the combined properties of Nb2O5 nanoparticles and α-Fe2O3 nanorods may produce a synergistic effect in electromagnetic shielding. The nanocomposite material can utilize the electrical conductivity and magnetism of α-Fe2O3 and the dielectric properties of Nb2O5 to provide a broad-spectrum electromagnetic shielding effect, achieving the shielding effect by combining reflection, absorption and multiple scattering mechanisms.

[0053] The materials prepared in Example 1, Comparative Example 1 and Comparative Example 2 were respectively embedded in a silicone elastomer matrix through mechanical mixing and solution mixing techniques to obtain NF heterostructure nanocomposites / silicone elastomers, Nb2O5 nanoparticles / silicone elastomers and α-Fe2O3 nanorods / silicone elastomers. Electromagnetic measurement tests were carried out and the relative complex dielectric constant and complex permeability were used for analysis.

[0054] Preparation of NF heterostructure nanocomposites / organic silicone elastomer, Nb2O5 nanoparticles / organic silicone elastomer, and α-Fe2O3 nanorods / organic silicone elastomer, the specific steps are as follows:

[0055] First, by adding Dow Corning Sylgard TM The polymer matrix and curing agent of the 184 Silicon Encapsulant Clear Kit were thoroughly mixed in a weight ratio of 10:1 to prepare a silicon solution. The prepared NF heterostructure nanocomposite was then incorporated into the silicon solution. The mixture was then internally mixed at 180 rpm for 30 minutes to ensure uniform dispersion of the particles within the silicon matrix. The well-dispersed NF / silicon mixture was then molded into a 22.86 mm × 10.16 mm × 2 mm 3 The samples were cured at 100℃ for 25min and then used for electromagnetic measurement. Similarly, Nb2O5 / silicon mixtures and α-Fe2O3 / silicon mixtures were prepared using the same method and technology.

[0056] The specific analysis is as follows:

[0057] like Figure 3 As shown, Figure 3 (a) and Figure 3 (b) shows the complex dielectric constant and complex permeability (real and imaginary parts) spectra of Nb2O5 nanoparticles (NPs), α-Fe2O3 nanorods (NRs), and NF heterostructured nanocomposites in the frequency range of 8.2 to 12.4 GHz (X-band). The ε′ values of all samples remain high and stable throughout the frequency range, and the ε′ value of the NF sample reaches a peak of approximately 22. Similarly, the ε″ values of all samples are relatively stable in frequency, but the NF sample exhibits some oscillation behavior at low frequencies. For the Nb2O5 nanoparticles and α-Fe2O3 nanorod samples, the ε″ values are large, indicating that their dielectric loss is relatively low, while the dielectric loss of the NF sample is small. The integration of Nb2O5 nanoparticles and α-Fe2O3 nanorods acts as tiny dipoles, which are polarized in the electromagnetic field, resulting in increased microwave absorption due to the increase in the complex dielectric constant. The NF samples exhibited low dielectric loss, demonstrating their effectiveness in reducing energy dissipation, which would improve microwave absorption performance and enhance electromagnetic interference (EMI) shielding effectiveness.

[0058] Figure 3 (c) and Figure 3(d) in the figure shows the real and imaginary parts of the complex permeability (μ = μ′-jμ″) in the X-band. Some large fluctuations appear due to the natural resonance caused by the eddy current effect of the ferromagnetic particles and the enhanced surface anisotropy caused by the small size of the α-Fe2O3 nanorods. In addition, the higher anisotropy energy also contributes to the enhancement of microwave absorption. Due to the presence of magnetic components in the NF sample, the μ′ value is relatively lower than that of the sample composed only of Nb2O5 nanoparticles and α-Fe2O3 nanorods, which reflects the enhancement of electromagnetic energy loss. In addition, when the composite heterostructure with large interfacial polarization faces an alternating electromagnetic field, an electric current is excited, thereby forming a magnetic field opposite to the external electromagnetic field. Further, the generation of this opposite induced field will lead to fluctuations in the magnetic field energy, thereby contributing to the formation of a negative value of μ″.

[0059] Dielectric loss tangent (tanδ ε ) and magnetic loss tangent (tanδ μ ) are respectively given by tanδ ε =ε″ / ε′ and tanδ μ =μ″ / μ′ gives, as Figure 4 As shown, Nb2O5 nanoparticles (NPs) and α-Fe2O3 nanorods (NRs) exhibit higher dielectric and magnetic losses compared to NF nanocomposites. In the Nb2O5 and α-Fe2O3 samples, the dielectric loss is greater than the magnetic loss due to the weak magnetic properties of the composites. Therefore, the reflection loss is primarily due to electrical loss, while the magnetic loss is very small, indicating that the NF nanocomposites exhibit low losses, supporting their ability to store energy with minimal energy dissipation. This property makes the NF nanocomposites ideal for applications such as capacitors, insulators, and other electronic components.

[0060] According to the Debye theory, the dielectric relaxation behavior of NF nanocomposites is described by the Cole-Cole plot, as shown in Figure 5 As shown in Figure 2, the Cole-Cole plots of Nb2O5 nanoparticles (NPs), α-Fe2O3 nanorods (NRs) and NF heterostructured nanocomposites are shown. The semicircles in the figure are complex in shape, significantly distorted and overlapping, confirming the presence of multiple polarization relaxation mechanisms at the interfaces of these samples. Therefore, the dielectric losses associated with these different polarizations should be the main contributors to the electromagnetic (EM) losses in the composite. In addition, it was found that more linear tails of the semicircles can be observed only in the NF nanocomposite samples, indicating that the conductive losses caused by the conductive network developed in the NF nanocomposite cannot be ignored, as shown in Figure 2. Figure 5 As shown in (c) in .

[0061] like Figure 6As shown, NF nanocomposites exhibit the lowest reflection shielding effectiveness (SE) in the entire X-band microwave frequency range. R ), close to zero. This means that more than 99.999% of the electromagnetic (EM) energy entering the material is absorbed. R Based on electrical conductivity, lower electrical conductivity will reduce the generation of eddy currents. Therefore, the energy of the electromagnetic wave field is reduced by ohmic electrothermal heating, and the reverse field generated is weaker, resulting in reduced reflection, thereby improving EMI shielding performance. Compared with other samples, the NF nanocomposite has a moderate electrical conductivity, which makes it show the lowest SE R value.

[0062] In summary, two primary loss mechanisms, primarily driven by the magnetic and conductive properties of Nb2O5 NPs and α-Fe2O3 NRs, dominate the attenuation of incident microwave energy in NF heterostructured nanocomposites. These two mechanisms play a dominant role in NF heterostructured nanocomposites. First, the electrical component of the electromagnetic field is attenuated or absorbed. The conductive properties of Nb2O5 nanoparticles (NPs) and α-Fe2O3 nanorods (NRs) contribute to dielectric losses. These two mechanisms work together to effectively attenuate electromagnetic energy in NF heterostructured nanocomposites. Furthermore, the two metal oxides exhibit unique synergistic effects, including dipole polarization, interfacial polarization, microcapacitance, and conductive losses, providing a rational synthetic route for exploring advanced functional materials and opening up new research opportunities.

[0063] Therefore, the present invention adopts the above-mentioned heterostructure composite material with high shielding effectiveness, preparation method and application, and synthesizes NF heterostructure nanocomposite material by double hydrothermal method. The synergistic effect of niobium pentoxide and trivalent iron oxide and morphology control significantly improve its overall shielding effectiveness, which has important value in the fields of modern electronics and technology.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a heterogeneous structure composite material with high shielding effectiveness, characterized in that: The following steps are involved: S1. Mix Nb2O5, FeCl3·6H2O and Na2SO4·10H2O in deionized water in a certain proportion to obtain a uniform solution; S2. The uniform solution obtained in S1 is transferred to a sealed container, subjected to constant temperature heating treatment, and then annealed in an air environment to obtain a precipitate, which is cooled to room temperature. After centrifugation and washing, the NF heterostructured nanocomposite material is obtained.

2. The method for preparing a heterogeneous structure composite material with high shielding effectiveness according to claim 1, characterized in that: In S1, the mass ratio of the Nb2O5, the FeCl3·6H2O, the Na2SO4·10H2O and the deionized water is 0.05-0.15 g: 0.01-0.02 g: 0.05-0.07 g: 25-35 ml.

3. The method for preparing a heterogeneous structure composite material with high shielding effectiveness according to claim 1, characterized in that: In S2, the constant temperature heating treatment is specifically as follows: Maintain the temperature within the range of 160°C to 200°C for 10 hours to 14 hours.

4. The method for preparing a heterogeneous structure composite material with high shielding effectiveness according to claim 1, characterized in that: In S2, the annealing treatment is specifically as follows: Annealing is performed at a heating rate of 1°C / min to 3°C / min in a temperature range of 450°C to 550°C for 2h to 4h.

5. The method for preparing a heterogeneous structure composite material with high shielding effectiveness according to claim 1, characterized in that: In S2, the washing is performed multiple times using ethanol and deionized water.

6. A NF heterostructure nanocomposite material prepared by the method for preparing a heterostructure composite material with high shielding effectiveness according to any one of claims 1 to 5.

7. Use of the NF heterostructure nanocomposite material according to claim 6 in capacitors, insulators and other electronic components.

8. The use according to claim 7, characterized in that The NF heterostructured nanocomposite material was embedded in a silicone elastomer matrix by mechanical mixing and solution mixing techniques to obtain a sample for electromagnetic shielding.

9. The use according to claim 8, characterized in that The following steps are involved: Step 1: Mixing a polymer matrix and a curing agent in a certain proportion to prepare a silicon solution; Step 2: The NF heterostructure nanocomposite material is added to the silicon solution, dispersed and then solidified to obtain a sample.

10. The use according to claim 9, characterized in that Step 2 is as follows: The NF heterostructured nanocomposite was incorporated into the silicon solution and internally mixed at 180 rpm for 30 min to obtain a NF / silicon mixture with particles uniformly dispersed in the silicon matrix. The mixture was then cured at 100°C / min for 25 min to obtain a NF heterostructured nanocomposite / silicone elastomer.

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