CORE-SHELL STRUCTURE TYPE WAVE ABSORBING MATERIAL, PREPARATION METHOD THEREFOR, AND APPLICATION

Abstract

Disclosed are a core-shell structure type wave absorbing material and a preparation method therefor. The wave absorbing material has a core-shell structure with two-dimensional transition metal-chalcogen compound nanosheets as cores and hollow carbon spheres as shells. The preparation method includes: dissolving the hollow carbon spheres in a solvent, sequentially adding a transition metal source and a chalcogen source, taking a solvothermal reaction after dissolution through stirring, and then performing posttreatment to obtain the wave absorbing material. The present invention further discloses an application of the wave absorbing material in fields of military and civilian high-frequency electromagnetic compatibility and protection. The core-shell structure type wave absorbing material of the present invention has a density of 0.3 to 1.5 g/cm.sup.3, a maximum reflection loss value and an effective bandwidth of the material can be effectively improved in a frequency range of 2 to 40 GHz, and the core-shell structure type wave absorbing material is an electromagnetic compatibility and protection material capable of meeting requirements of civilian high-frequency electronic devices and military weapons and equipment such as airships and artillery shells.

Claims

1. A core-shell structure type wave absorbing material, having a core-shell structure with two-dimensional transition metal-chalcogen compound nanosheets as cores and hollow carbon spheres as shells, wherein the transition metal is selected from Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Nb, Mo, Hf, Ta, W and Re, and the chalcogen is selected from S, Se and Te.

2. The core-shell structure type wave absorbing material according to claim 1, wherein a matching thickness of the wave absorbing material in a frequency band of 2 to 40 GHz is 0.5 to 5.0 mm, a maximum reflection loss (RL) is −40 to 80 dB, and an effective absorption bandwidth with a RL smaller than −10 dB is 2.5 to 12 GHz.

3. A preparation method for the core-shell structure type wave absorbing material according to claim 1, comprising: dissolving the hollow carbon spheres in a solvent, sequentially adding a transition metal source and a chalcogen source, taking a solvothermal reaction after dissolution through stirring, and then performing posttreatment to obtain the wave absorbing material.

4. The preparation method for the core-shell structure type wave absorbing material according to claim 3, wherein a reaction temperature of the solvothermal reaction is 180 to 230° C., and a reaction time is 10 to 35 hours.

5. The preparation method for the core-shell structure type wave absorbing material according to claim 3, wherein a diameter of the hollow carbon sphere is 200 to 400 nm.

6. The preparation method for the core-shell structure type wave absorbing material according to claim 3, wherein the solvent is a mixed solution of an amine reagent and an alcohol reagent, and a volume ratio of the amine reagent to the alcohol reagent is (4 to 6):1.

7. The preparation method for the core-shell structure type wave absorbing material according to claim 6, wherein the amine reagent is formamide or caprolactam, and the alcohol reagent is one or a mixture of more of methanol, ethanol and isopropanol.

8. The preparation method for the core-shell structure type wave absorbing material according to claim 3, wherein the transition metal source comprises a sodium salt, a chloride salt or a thioammonium salt of a transition metal, and the chalcogen source comprises an ammonium salt, a chloride salt or an oxide of a chalcogen.

9. The preparation method for the core-shell structure type wave absorbing material according to claim 3, wherein a molar ratio of the transition metal to the chalcogen is 1:(1 to 6).

10. An application of the core-shell structure type wave absorbing material according to claim 1 in fields of military and civilian high-frequency electromagnetic compatibility and protection.

11. A preparation method for the core-shell structure type wave absorbing material according to claim 2, comprising: dissolving the hollow carbon spheres in a solvent, sequentially adding a transition metal source and a chalcogen source, taking a solvothermal reaction after dissolution through stirring, and then performing posttreatment to obtain the wave absorbing material.

12. An application of the core-shell structure type wave absorbing material according to claim 2 in fields of military and civilian high-frequency electromagnetic compatibility and protection.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG. 1 is an XRD spectrum of a core-shell structure type MoS.sub.2@HCS wave absorbing material prepared in Embodiment 1.

[0034] FIG. 2 is SEM and TEM images of the core-shell structure type MoS.sub.2@HCS wave absorbing material prepared in Embodiment 1.

[0035] FIG. 3 is a RL spectrum of the core-shell structure type MoS.sub.2@HCS wave absorbing material prepared in Embodiment 1 at a frequency band of 2 to 40 GHz.

[0036] FIG. 4 is a RL spectrum of a core-shell structure type WS.sub.2@HCS wave absorbing material prepared in Embodiment 2 at a frequency band of 2 to 18 GHz.

[0037] FIG. 5 is a RL spectrum of a core-shell structure type VTe.sub.2@HCS wave absorbing material prepared in Embodiment 3 at a frequency band of 2 to 18 GHz.

[0038] FIG. 6 is a RL spectrum of a core-shell structure type NbSe.sub.2@HCS-1 wave absorbing material prepared in Embodiment 4 at a frequency band of 2 to 18 GHz.

[0039] FIG. 7 is a RL spectrum of a core-shell structure type NbSe.sub.2@HCS-2 wave absorbing material prepared in Embodiment 5 at a frequency band of 2 to 18 GHz.

[0040] FIG. 8 is a RL spectrum of a core-shell structure type NbSe.sub.2@HCS-3 wave absorbing material prepared in Embodiment 6 at a frequency band of 2 to 18 GHz.

[0041] FIG. 9 is a RL spectrum of an HCS wave absorbing material prepared in Comparative example 1 at a frequency band of 2 to 18 GHz.

DESCRIPTION OF THE EMBODIMENTS

[0042] The present invention will be further described hereafter with reference to the accompanying drawings and specific embodiments, but they are not intended to limit the protection scope of the present invention. Materials and instruments used in the embodiments below were all commercially available in the market.

Embodiment 1

[0043] (1) High-dispersibility hollow carbon spheres were prepared by a Stober method (Reference: Werner Stober et.al. Controlled Growth of Monodisperse Silica Spheres in the Micron Size Range, Journal of colloid and interface science, 1968, 26, 62-69). 100 mg of prepared hollow carbon spheres (with a particle size of 250 nm) were taken and put into a 50 mL beaker. 25 mL of formamide and 5 mL of methanol were added to obtain a mixed solution through sufficient stirring for 1 hour. 2.0 g of sodium molybdate dihydrate (Na2MoO4.2H2O) and 4.0 g of thioacetamide (CH3CSCH2) were respectively weighed and sequentially added into the above mixed solution, and were respectively stirred for 2 hours for sufficient dissolution, then an obtained reaction solution was transferred to a 50 mL solvothermal reaction inner lining, the inner lining was placed into a stainless steel outer sleeve to be sealed, and reaction was performed for 24 h under the condition of 200° C.

[0044] (2) After the reaction was completed, the product was put into a centrifugal tube to be subjected to 10000 rpm high-speed centrifugation for 20 minutes, a product at the tube bottom was taken, was washed for 2 to 3 times respectively by deionized water and absolute ethanol, and was then placed into an 85° C. baking oven to be dried for 15 hours to obtain a final product, and the final product was a core-shell structure type MoS.sub.2@HCS wave absorbing material.

[0045] A crystal structure of the product was tested by an X-ray diffractometer (XRD, model: Bruker D8 Advance), and the result was as shown in FIG. 1. A diffraction peak at 13.5° belonged to a (002) crystal face of molybdenum disulfide, a diffraction peak at 33.5° belonged to a (100) crystal face of molybdenum disulfide, and a bulge peak at 45° belonged to a (101) crystal face of a typical carbon material. Integrally, compared with that of blocky materials, the crystal phase of the core-shell structure type MoS.sub.2@HCS material prepared in Embodiment 1 had the reduced crystallinity degree, and conformed to the general characteristics of a nanometer material.

[0046] A microstructure of the material was observed by a field emission scanning electron microscope (SEM; model: Hitachi S-4800), and a result was as shown in FIG. 2(a). An SEM result showed that the core-shell structure type MoS.sub.2@HCS material prepared in Embodiment 1 had excellent dispersibility, and an average size was 260 nm.

[0047] A core-shell structure of the material was observed by a field emission transmission electron microscope (TEM; model: FEI Tecnai G2 F20S-TWIN), and a result was as shown in FIG. 2(b). A TEM result showed that MoS.sub.2 thin sheets were located inside the materials, the carbon spheres were used as shells, and the MoS.sub.2 thin sheets and the carbon spheres formed significant core-shell structures.

Embodiment 2

[0048] Preparation steps were basically identical to those in Embodiment 1. The difference was only that sodium molybdate dihydrates in step (1) were replaced by sodium tungstate to prepare a core-shell structure type WS.sub.2@HCS composite microwave absorbing agent.

Embodiment 3

[0049] Preparation steps were basically identical to those in Embodiment 1. The differences were only that sodium molybdate dihydrates in step (1) were replaced by sodium vanadate, and the thioacetamide was replaced by sodium tellurate to prepare a core-shell structure type VTe.sub.2@HCS composite microwave absorbing agent.

Embodiment 4

[0050] Preparation steps were basically identical to those in Embodiment 1. The differences were only that sodium molybdate dihydrates in step (1) were replaced by sodium niobate, and the thioacetamide was replaced by sodium selenate or sodium selenite to prepare a core-shell structure type NbSe.sub.2@HCS-1 wave absorbing material.

Embodiment 5

[0051] Preparation steps were basically identical to those in Embodiment 4. The difference was only that the reaction temperature in step (1) of Embodiment 4 was changed from 200° C. into 230° C., and other reaction conditions were identical to prepare a core-shell structure type NbSe.sub.2@HCS-2 wave absorbing material.

Embodiment 6

[0052] Preparation steps were basically identical to those in Embodiment 4. The differences were only that the formamide in step (1) of Embodiment 4 was replaced by caprolactam, the methanol was replaced by ethanol, and other reaction conditions were identical to prepare a core-shell structure type NbSe.sub.2@HCS-3 wave absorbing material.

Comparative Example 1

[0053] Preparation steps were basically identical to those in Embodiment 1. The difference was only that sodium molybdate dihydrates and thioacetamide were not added in step (1) to prepare a HCS wave absorbing material.

[0054] The wave absorbing materials prepared in Embodiments 1 to 6 and Comparative example 1 were respectively and uniformly mixed with molten paraffin according to a mass ratio of 1:1 (i.e., the content of the absorbing agents was 50%), and the mixture was prepared into a standard coaxial ring test sample with an inner diameter of 3.0 mm, an outer diameter of 7.0 mm and a thickness of 2.0 mm in a purpose-made mold. The electromagnetic wave absorption characteristics of each sample in 2 to 40 GHz were respectively tested by using a coaxial and wave guide method and utilizing a vector network analyzer (VNA; model: AgilentN5234A).

[0055] The electromagnetic wave absorption performance of a test sample prepared from the MoS.sub.2@HCS wave absorbing material according to Embodiment 1 was as shown in FIG. 3. From FIG. 3(a), it could be known that when the matching thickness was 2.0 mm, the effective bandwidth in the frequency band of 2 to 18 GHz was 3.6 GHz, and the maximum RL was −60 dB. From FIG. 3(b), it could be known that when the matching thickness was 1.0 mm, the effective bandwidth in the frequency band of 18 to 26.5 GHz was 6 GHz, and the maximum RL was −50 dB. From FIG. 3(c), it could be known that when the matching thickness was 0.6 mm, the effective bandwidth in the frequency band of 26.5 to 40 GHz was 10 GHz, and the maximum RL was −45 dB.

[0056] The electromagnetic wave absorption performance of a test sample prepared from the WS.sub.2@HCS wave absorbing material according to Embodiment 2 was as shown in FIG. 4. From FIG. 4, it could be known that at the frequency band of 2 to 18 GHz and the matching thickness of 1.9 mm, the wave absorbing material had the maximum RL of −55 dB, and the EAB of 4 GHz.

[0057] The electromagnetic wave absorption performance of a test sample prepared from the VTe.sub.2@HCS wave absorbing material according to Embodiment 3 was as shown in FIG. 5. From FIG. 5, it could be known that at the frequency band of 2 to 18 GHz and the matching thickness of 2.0 mm, the wave absorbing material had the maximum RL of −54 dB, and the EAB of 3.2 GHz.

[0058] The electromagnetic wave absorption performance of a test sample prepared from the NbSe.sub.2@HCS-1 wave absorbing material according to Embodiment 4 was as shown in FIG. 6. From FIG. 6, it could be known that at the frequency band of 2 to 18 GHz and the matching thickness of 2.1 mm, the wave absorbing material had the maximum RL of −58 dB, and the EAB of 2.6 GHz.

[0059] The electromagnetic wave absorption performance of a test sample prepared from the NbSe.sub.2@HCS-2 wave absorbing material according to Embodiment 5 was as shown in FIG. 7. From FIG. 7, it could be known that at the frequency band of 2 to 18 GHz and the matching thickness of 2.1 mm, the wave absorbing material had the maximum RL of −51 dB, and the EAB of 3 GHz.

[0060] The electromagnetic wave absorption performance of a test sample prepared from the NbSe.sub.2@HCS-3 wave absorbing material according to Embodiment 6 was as shown in FIG. 8. From FIG. 8, it could be known that at the frequency band of 2 to 18 GHz and the matching thickness of 2.1 mm, the wave absorbing material had the maximum RL of −50 dB, and the EAB of 3 GHz.

[0061] The electromagnetic wave absorption performance of a test sample prepared from the hollow carbon spheres according to Comparative example 1 was as shown in FIG. 9. From FIG. 9, it could be known that when the matching thickness was 2.0 mm, the maximum RL in 2 to 18 GHz was −28 dB, and the EAB was 3.0 GHz.

[0062] The above descriptions are merely typical embodiments of the present invention and are not intended to limit the present invention in any way. Anyone familiar with the art can use the methods and technical content disclosed above to make many possible changes and modifications to the solution of the present invention without departing from the technical core and solution of the present invention. Therefore, any content that does not depart from the technical solution of the present invention, and any simple changes, modifications, equivalent substitutions and equivalent changes made to the above embodiments based on the technical essence of the present invention belong to the protection scope of the technical solution of the present invention.