97 results about "Absorption bandwidth" patented technology

The invention provides a broadband absorption and transmission integrated frequency selective surface with a high selection characteristic, which comprises a first loss layer, a second loss layer and a frequency selection layer, and is characterized in that the first loss layer and the second loss layer realize a transmission band with the high selection characteristic and the broadband characteristic at the same time by using dual-order resonance; the second loss layer and the frequency selection layer are cascaded to realize the absorption and transmission integrated characteristic, and the first loss layer is used for improving the low-frequency and high-frequency wave absorption characteristics and expanding the wave absorption bandwidth. Under the combined action of the first loss layer, the second loss layer and the frequency selection layer, wave transmission within the frequency band of 7.72-11.89 GHz and wave absorption within the frequency band of 1.96-7.12 GHz and the frequency band of 12.95-17.33 GHz are achieved. The antenna has high selection characteristics and broadband characteristics, can effectively suppress interference of external electromagnetic waves of other frequency bands or electromagnetic waves of a frequency band close to a communication frequency band on communication, can reduce the radar cross section of a target, and facilitates target stealth.

The invention relates to the technical field of aerogel materials, in particular to a carbon-rich SiC-coated Si3N4 double-network aerogel and a preparation method thereof. The double-network aerogel comprises an inner framework and an outer framework, the inner framework is a SiC network, the outer framework is a Si3N4 network, the double-network aerogel is formed by interweaving the SiC network and the Si3N4 network, the SiC network and the Si3N4 network are rich in in-situ carbon, and the content of the in-situ carbon in the Si3N4 network is far smaller than that of the in-situ carbon in the SiC network. The aerogel disclosed by the invention successfully integrates multiple key properties, wherein high porosity and low thermal conductivity ensure excellent thermal insulation capability; the reflection loss reaches-60dB to the minimum, and the effective absorption bandwidth reaches 5GHz, so that the excellent broadband wave-absorbing performance is proved; the compressive strength of the material can reach 14 MPa or above, excellent mechanical reliability is shown, and an ideal solution is provided for electromagnetic protection and thermal management of high-end equipment.

This invention relates to a method for preparing a broadband absorption hydrogel. The method comprises the following steps: S1, mixing solvent A (N,N-dimethylformamide or acetonitrile) with deionized water to obtain a mixed solvent; S2, adding polyethylene glycol methyl ether acrylate-480 and acryloylmorpholine to the solvent in S1 and dissolving them to obtain a mixed solution; S3, removing dissolved oxygen from the mixed solution in S2, sealing the container, and stirring under ice bath conditions; S4, adding potassium persulfate and N,N,N',N'-tetramethylethylenediamine to the mixed solution after stirring in S3, and sealing the container again; S5, completing the polymerization reaction in the container at 60 °C to obtain the hydrogel. Compared with the prior art, the hydrogel material provided by this invention has improved reflection loss intensity and effective absorption bandwidth performance, thus providing a new perspective for developing highly flexible and efficient electromagnetic wave absorbers.

The invention discloses a multifunctional broadband electromagnetic wave-absorbing composite material based on a bionic periodic unit and a multistage core-shell filler and a preparation method thereof.The multistage core-shell filler is used as a raw material, an impregnation technology is adopted, and the bionic periodic unit is impregnated by preparing high-loss paint and impedance matching paint with different concentrations; the electromagnetic wave-absorbing composite material is obtained. Accurate gradient distribution and better impedance matching of electromagnetic parameters in a three-dimensional space are achieved, the density is lower than 6 kg / m under the thickness of 15-20 mm, the plane compression strength is 2 MPa, and the effective absorption bandwidth (RLlt;-10 dB) covers 8-18 GHz. The invention solves the contradiction between the bandwidth, thickness, weight and single function of the traditional wave-absorbing material, and is suitable for the fields of advanced stealth equipment and electromagnetic protection. The material opens up a new direction for the development of electromagnetic wave-absorbing materials, and is expected to be widely applied to many fields such as national defense, communication, electronics and the like.

The invention discloses a Ni3Al-PPy composite wave-absorbing material as well as a preparation method and application thereof, and belongs to the technical field of electromagnetic wave-absorbing materials. The Ni3Al-PPy composite wave-absorbing material with a core-shell structure is successfully synthesized by combining a thermit reaction with a chemical oxidation polymerization method and hydrochloric acid modification. By regulating and controlling the addition amount of the pyrrole monomer in the range of 0.25-0.75 mL, the continuous regulation and control of the thickness of the PPy shell layer from 0.22 [mu] m to 0.31 [mu] m is realized. When the thickness of a PPy shell layer is 0.27 mu m and the matching thickness of the composite wave-absorbing material is 3.0 mm, the minimum reflection loss and absorptivity gt of-40.0 dB are obtained at 9.27 GHz; and when the matching thickness is 2.0 mm, the effective absorption bandwidth reaches 3.02 GHz. According to the invention, the effect of the shell layer thickness in regulating and controlling the performance of the wave-absorbing material with the core-shell structure is illustrated, and a feasible strategy is provided for designing a high-performance light-weight wave-absorbing material with adjustable electromagnetic parameters and enhanced durability.

A method for preparing a MOF-based multiphase composite electromagnetic wave absorbing material is disclosed, which relates to the preparation method and application of electromagnetic wave absorbing materials. The purpose of this invention is to solve the problems of poor attenuation and narrow absorption bandwidth in ABO3-type perovskite electromagnetic wave absorbing materials prepared by existing methods. This invention is based on the metallic Fe in MIL-88A. 3+ Ions were successfully induced to form an oxide perovskite phase in MIL-88A via etching, resulting in a hierarchical hollow nanocomposite material. In this structure, the oxide perovskite, a typical spinel-type p-type semiconductor, is composited with the surrounding elemental Fe phase through an outer graphitized carbon shell. Utilizing the heterojunction effect with metal-semiconductor contacts, an excellent interfacial polarization process is generated, significantly enhancing the dielectric loss performance of the composite material. Simultaneously, by consuming excess Fe metal... 3+ Excellent electromagnetic wave absorption performance was obtained by adjusting the impedance matching of the composite material.

The invention discloses a method for preparing a high-performance wave-absorbing material by in-situ construction of a polar organic coating through cooperation of microwaves and AlCl3-NaCl molten salt, and relates to the technical field of new material synthesis. Cutting, cleaning and drying the waste carbon fiber reinforced resin-based composite material to obtain a clean composite material a; the preparation method comprises the following steps: weighing a composite material a and AlCl3-NaCl molten salt, enabling the AlCl3-NaCl molten salt to be in full contact with the composite material a, carrying out microwave molten salt in-situ pyrolysis in a microwave oven under the protection of a protective atmosphere, and realizing in-situ construction of a polar organic nano coating on the surface of the carbon fiber by utilizing microwave and AlCl3-NaCl molten salt catalysis treatment; and repeatedly washing with deionized water, and carrying out suction filtration and drying to obtain the organic coating / carbon fiber wave-absorbing composite material. When the thickness of the prepared organic coating / carbon fiber composite material is 1.4-4.0 mm, the reflection loss can reach-40.20--69.00 dB, the effective absorption bandwidth is 2.2-4.05 GHz, and the organic coating / carbon fiber composite material has light and thin characteristics and excellent electromagnetic wave absorption, is excellent in electromagnetic wave absorption performance and has a relatively good application prospect.

This invention belongs to the field of microwave absorbing materials technology, and discloses a SiBCN-ZrO2 ceramic composite material with high temperature resistance, oxidation resistance, and full X-band absorption, as well as its preparation method. First, SiBCN and ZrO2 polymer liquid-phase precursors are uniformly mixed, followed by low-temperature curing and high-temperature pyrolysis heat treatment, ultimately obtaining a SiBCN-ZrO2 ceramic composite material with ZrO2 uniformly distributed in an amorphous SiBCN matrix. This ceramic composite material has an effective absorption bandwidth of 4.2 GHz in the X-band, compared to 3.65 GHz for pure PDC-SiBCN ceramic, demonstrating an improved effective absorption bandwidth that covers the entire X-band, and also improving oxidation resistance. The preparation process of the SiBCN-ZrO2 ceramic composite material prepared by this invention is simple and can effectively improve the insufficient dielectric loss capacity of PDC-SiBCN ceramic as a microwave absorbing material, enhancing the overall high-temperature resistance and oxidation resistance of the material.

The invention discloses a cubic ZIF-67 / MXene wave-absorbing material as well as a preparation method and application of the cubic ZIF-67 / MXene wave-absorbing material. The preparation method comprises the following steps: reacting lithium fluoride, concentrated hydrochloric acid and deionized water to generate hydrofluoric acid, and etching an MAX phase to obtain MXene; the preparation method comprises the following steps: dispersing CoCl2. 6H2O, cetyl trimethyl ammonium bromide (CTAB) and MXene in deionized water to form a solution A; dispersing 2-methylimidazole in deionized water to form a solution B; quickly pouring the solution A into the solution B, stirring and reacting, centrifuging, freeze-drying and annealing to obtain the cubic ZIF-67 / MXene wave-absorbing material. The material is of a multi-layer sandwich structure, the reflection loss at 16.69 GHz can reach-20.79 dB, the matching thickness is 1.87 mm, the effective absorption bandwidth (RL is smaller than or equal to-10 dB) is 6.19 GHz (11.81-18.00 GHz), and the Ku wave band is covered. The method is environment-friendly in process, low in cost, simple and convenient to operate and suitable for large-scale production, and has application prospects in the fields of microwave absorption, infrared stealth and photocatalysis.

This application provides a filler for an encapsulation material and its preparation method, a magnetic molding compound, and an encapsulation device. The filler for the encapsulation material includes ferrite particles, wherein the ferrite particles include nickel-copper-zinc ferrite (Ni... a Zn b Cu c Fe d The O4 material has the following properties: a ranges from 0.3 to 0.55, b ranges from 0.45 to 0.55, c ranges from 0 to 0.2, and d ranges from 1.8 to 2. The ferrite particles have a particle size of 2-11 μm, accounting for 50-70% of the total. This filler has advantages such as low relative density, wide absorption bandwidth, and good high and low temperature performance, thereby reducing the overall weight of the packaged device and improving its electromagnetic interference resistance and applicable temperature range.

This application discloses a broadband sound absorption structure for an air conditioner compressor, comprising: a carrier; multiple sound-absorbing units arranged in a matrix on the carrier; each sound-absorbing unit having multiple sound-absorbing cavities spaced apart and sound-absorbing holes formed on the surface of each sound-absorbing cavity; multiple sound-absorbing holes of the same sound-absorbing unit being on the same horizontal line and the hole size gradually increasing from one side to the other; and the hole wall of each sound-absorbing hole extending towards the sound-absorbing cavity; through the matrix arrangement of sound-absorbing units and their hole size gradient design, a multi-band Helmholtz resonant cavity is formed, utilizing the resonant frequency difference corresponding to different hole sizes to cover broadband sound absorption requirements from low frequency (80Hz) to high frequency (8000Hz); at the same time, the regular matrix arrangement enhances the sound wave scattering effect, increasing the sound absorption bandwidth by about 60% compared to traditional structures.

The invention discloses an adjustable ultra-wideband terahertz metamaterial wave absorber, and belongs to the technical field of terahertz wave absorbers. The wave absorber is composed of a plurality of same metamaterial structure units which are periodically arranged, and each metamaterial structure unit is made of three layers of composite materials, wherein the first layer is a graphene pattern layer, the second layer is a polyimide dielectric layer, and the third layer is a copper reflecting layer. Wherein the graphene pattern layer adopts a combined design of four groups of square and L-shaped structures, and the four groups of structures form a biaxial symmetry layout through geometric coupling. The structure has the characteristics of wide absorption bandwidth, high absorption rate and dynamic adjustability, can realize more than 90% of efficient absorption in the frequency band of 2.28-4.68 THz, and can adjust the Fermi level of the graphene by externally applying bias voltage to realize rapid switching between the absorption state and the reflection state. The device is suitable for various application scenes such as terahertz communication, sensing and stealth.

The present application relates to wave-absorbing material technical field, specifically to a kind of nitrogen-doped carbon / cobalt-based wave-absorbing agent and its preparation method and application.The specific preparation method includes the following steps: with nitrogen-doped carbon nanosheet as matrix, 2-methyl imidazole as organic ligand, under solvent system, with Co source is co-precipitated, make the ZIF-67 formed on nitrogen-doped carbon nanosheet, then under protective atmosphere, at 700 DEG C~900 DEG C pyrolysis, obtain nitrogen-doped carbon / cobalt-based wave-absorbing agent.The carbon nanosheet stable structure of preparation supported cubic ZIF-67, so that the Co / NCS composite material after pyrolysis exists heterostructure interface, strengthens multiple loss mechanism.The wave-absorbing agent can be used to prepare electromagnetic wave absorbing material, under lower filling amount, higher reflection loss and wider effective absorption bandwidth are realized.The existing wave-absorbing material exists the problem of narrow effective absorption bandwidth and weak electromagnetic wave loss capacity.

The application relates to a ZrB2 / ZrC composite ceramic wave-absorbing material and a preparation method thereof, and belongs to the field of wave-absorbing materials. The material comprises ZrB2 and ZrC; the ZrB2 is connected with each other to form a space net structure; and the outer wall of the ZrB2 is coated with granular ZrC crystals to form a rough surface. The method is characterized in that ZrB2 is prepared by using a polymer conversion method; ZrC liquid-phase precursors are impregnated into the polymer conversion ZrB2 as a matrix; after sufficient impregnation, solidification is carried out; and after the solidified sample is heat treated, the polymer conversion ZrB2 / ZrC composite material is obtained. The ZrB2 / ZrC ceramic wave-absorbing material prepared by the application has a minimum reflection loss of -64.64 dB, and an effective absorption bandwidth of 6.94 GHz when the material thickness is 4.33 mm.

The invention discloses a preparation method of light high-strength super-hydrophobic carbon foam / SiO2 composite aerogel and application of the light high-strength super-hydrophobic carbon foam / SiO2 composite aerogel in icing prevention / microwave absorption. The preparation method comprises the following steps: by taking foamy carbon as a structural reinforcement, completely impregnating SiO2 sol into pores of the foamy carbon through vacuum impregnation, and then carrying out gelation, aging, replacement and normal-pressure drying to construct the light high-strength super-hydrophobic carbon foam SiO2 composite aerogel with the interpenetrating phase structure. The material has excellent compressive strength, anti-icing performance (21s rapid deicing performance under low voltage of 2V and ultra-long anti-icing time) and electromagnetic wave absorption characteristic, and dual-interface polarization formed by foamy carbon and SiO2 aerogel enables the minimum reflection loss of the composite aerogel to reach-22.6 dB and the absorption bandwidth to reach 4.48 GHz. The composite aerogel maintains the original structure and contact angle after multiple times of mechanical wear, the water contact angle is as high as 158.3 degrees, and the rolling angle is as low as 4.9 degrees.

The invention relates to the technical field of wave-absorbing materials, in particular to a SiBCN-Fe ceramic corrosion-resistant wave-absorbing material and a preparation method and application thereof. The preparation method comprises the following steps: preparing a hyperbranched PBSZ-SiH polymer in an argon atmosphere; under the protection of argon, ferric acetylacetonate is dissolved in anhydrous xylene, and then the hyperbranched PBSZ-SiH polymer is added for a reaction; collecting a solid phase to obtain a PBSZ-Fe ceramic precursor; heating the PBSZ-Fe ceramic precursor, and carrying out a cross-linking reaction; and grinding a product obtained after the cross-linking reaction into powder, and then performing high-temperature pyrolysis in an argon atmosphere to obtain the SiBCN-Fe ceramic. According to the SiBCN-Fe ceramic corrosion-resistant wave-absorbing material, in a 3.5 wt% NaCl / H2O solution, the corrosion potential (Ev) is 0.035 V, the corrosion current density (Icorr) is 6.295 * 10 <-7 > Acm <-2 >, and the SiBCN-Fe ceramic corrosion-resistant wave-absorbing material is superior to most corrosion-resistant wave-absorbing materials; the effective absorption bandwidth (EAB) of 8.16 GHz under 2.7 mm and the minimum reflection loss of-32.2 dB under 2 mm are achieved, and excellent corrosion resistance and excellent wave absorbing performance are achieved.

The invention discloses a vanadium dioxide-based terahertz broadband chiral absorber capable of being actively regulated and controlled, and belongs to the technical field of terahertz metamaterial design. The problems that an existing chiral terahertz absorber is narrow in absorption bandwidth and single in light absorption function are solved. The terahertz broadband chiral absorber sequentially comprises a reflection bottom layer, an intermediate dielectric layer and a top layer from bottom to top; the top layer is formed by arranging a plurality of structural units in an array; each structural unit is composed of a Z-shaped gold structure and four vanadium dioxide micron plates; the four vanadium dioxide micron discs are symmetrically arranged on the left side and the right side of the middle longitudinal arm respectively and attached to the edges of the left side and the right side of the middle longitudinal arm. The invention is used for the vanadium dioxide-based terahertz broadband chiral absorber capable of being actively regulated and controlled.

The application discloses a tunable bidirectional metamaterial light absorption device and an optimization and preparation method thereof, and relates to the technical field of metamaterial optical absorption devices; the bidirectional absorption device is a six-layer structure of metal-dielectric-metal-dielectric-metal-dielectric, and the device units thereof are sequentially a silver metal layer, a liquid crystal dielectric layer, a silver metal layer, a liquid crystal dielectric layer, a chromium metal layer and a silicon nitride ring from bottom to top; the bidirectional light absorption device can realize wideband absorption on top incident plane light and narrowband absorption on bottom incident plane light in a wavelength range of 0.6-1.6 microns. By changing the liquid crystal molecule deflection angle in the liquid crystal dielectric layer, the absorption rate and the absorption bandwidth range of the device on the top or bottom incident light can be adjusted and controlled, so that tunability is realized. The application can realize the structural parameter optimization design of the device under multiple target constraints.

This invention discloses a magnetic amorphous carbon composite aerogel fiber, its preparation method, and its applications, belonging to the field of electromagnetic functional materials. The aerogel fiber has a continuous fiber morphology, composed of an amorphous carbon three-dimensional network framework and uniformly embedded MOF-derived magnetic nanoparticles. The core of its preparation method involves blending transition metal MOF nanoparticles with aramid nanofiber dossile, wet spinning through a unique "MOF-induced-protonation" synergistic gelation mechanism, followed by high-temperature carbonization, which transforms the MOF into magnetic particles in situ and anchors them within the carbon framework. This method is highly versatile and applicable to various MOFs such as Fe, Co, Ni, and Mn, and is simple and can be continuously produced. The resulting aerogel fiber possesses ultra-low density, high flexibility, and excellent broadband strong absorption performance (effective absorption bandwidth ≥ 7.0 GHz, reflection loss ≤ -50 dB), showing broad application prospects in wearable electronics, aerospace stealth, and 5G communication electromagnetic protection.

The invention belongs to the technical field of aerogel wave-absorbing materials, and particularly relates to trimetal MOFs / MXene derived aerogel as well as a preparation method and application thereof. According to the preparation method, Ni (NO3) 2.6 H2O, Co (NO3) 2.6 H2O and Cu (NO3) 2.3 H2O are used as metal sources, water-induced self-assembly, freeze drying and heat treatment are performed to prepare the aerogel, and the aerogel is of a 0D / 1D / 2D composite structure and contains nano twin crystals. The MXene content and the filler content are regulated and controlled to optimize the performance, the minimum reflection loss of the optimal sample NiCoCu / MX5-A reaches-83.73 dB, and the effective absorption bandwidth is 6.46 GHz. The aerogel has the advantages of light weight (9.2 mg.cm <-3 >), heat insulation, 82.93% photothermal conversion efficiency, 102.4 kPa compressive strength and hydrophobic property, is suitable for the fields of electromagnetic protection and the like, and provides support for design of multi-element aerogel-based wave-absorbing materials.

This invention belongs to the field of polymer composite materials technology, specifically disclosing a microwave absorbing composite material, its preparation method, and its applications. The microwave absorbing composite material uses polycarbonate / acrylonitrile-butadiene-styrene copolymer as the matrix and includes sheet-like carbonyl iron, whisker carbon nanotubes, antioxidants, flame retardants, and lubricants. Through the synergistic effect of whisker carbon nanotubes and sheet-like carbonyl iron, this microwave absorbing composite material achieves excellent broadband microwave absorption performance at an extremely thin thickness (1.5 mm): the effective absorption bandwidth (reflection loss ≤ -10 dB) covers 10.48~17.68 GHz, and more than 90% of the single effective absorption bandwidth reaches 7.2 GHz. The preparation process of this invention is simple, and the resulting microwave absorbing composite material can significantly improve its electromagnetic compatibility and anti-interference ability, showing broad application prospects in electronic devices such as laptops, mobile phones, and routers that require lightweight and thin designs.

The present application relates to nanometer wave-absorbing material preparation and marine environment wave-absorbing coating preparation technical field, especially disclose a kind of light weight marine environment resistant wave-absorbing coating and preparation method thereof, the wave-absorbing coating includes nanometer light density wave-absorbing agent coating pre-dispersion, nanometer dielectric loss type heavy density wave-absorbing agent and curing agent;And nanometer light density wave-absorbing agent coating pre-dispersion includes the material of high crystalline carbon-coated single-walled carbon nanotube prepared by in-situ, the high crystalline carbon-coated single-walled carbon nanotube structure is stable, not only has excellent wave-absorbing characteristics, while having good corrosion resistance.The wave-absorbing coating coating thickness prepared by the present application is 10mm, in 2-18GHz frequency range, wherein ≤-10dB absorption bandwidth is more than 11.6GHz, while meeting the neutral salt spray condition after 1200h, reflectivity change is ±5%, can improve the environmental adaptability and life of wave-absorbing coating.

The invention records a copper cluster-carbon black composite wave-absorbing material, and the copper cluster is an atomic-scale wave-absorbing performance enhancer and has an obvious enhancement effect on the wave-absorbing performance of a cheap universal commercially available carbon black material. A small amount of atomic clusters are added to the surface of cheap commercially available carbon black through a simple physical and mechanical stirring and mixing process, and the result shows that the wave-absorbing performance of carbon is improved by 3.46 times through the addition amount of only 3 wt% of copper clusters Cu6. When the thickness of a prepared sample is 2.2 mm, the maximum absorption bandwidth obtained within the range of 12.24 to 17.8 GHz is 5.56 GHz; and when the thickness is 3.5 mm, the maximum wave absorbing efficiency is-73.16 dB.

The invention relates to the technical field of magnetic wave absorption, in particular to a magnetic wave absorbing material and a preparation method and application thereof.The preparation method of the magnetic wave absorbing material comprises the steps that a multi-layer Mxene material Ti3C2Tx is mixed with a solution containing soluble Fe salt, soluble Ni salt, soluble Zn salt and a nitrogen-containing material, a hydrothermal reaction is conducted, solid is obtained through separation, and washing, drying and reduction are conducted; in the mixed solution, the mass content of the multi-layer Mxene material Ti < 3 > C < 2 > T < x > is 0.1-50 g / L, and the Fe element content is 0.1-100 mmol / L; the molar ratio of the Fe element to the Ni element is 1: (0.5-5); the molar ratio of the Fe element to the Zn element is 1: (0.1-0.8); the content of the nitrogen-containing material is 5-1000 mmol / L; the nitrogen-containing material is selected from one or more of urea and C1-C8 organic amine. The prepared magnetic wave absorbing material comprises an Mxene material and a TiO2, FeNi alloy and ZnO composite material loaded on the Mxene material, and is used for absorbing electromagnetic waves, so that the wave absorbing performance can be remarkably improved, the minimum reflection loss is low, the maximum effective absorption bandwidth is wider, and the impedance is reduced.

The invention discloses a preparation method of a hierarchical heterogeneous interface magnetic-dielectric synergistic wave-absorbing material. The preparation method comprises the following steps: carrying out liquid-phase shearing and stripping on expanded graphite to obtain a flaky few-layer graphite dispersion liquid; a nickel-iron layered double hydroxide enrichment micro-area is constructed on the surface and the edge of the nickel-iron layered double hydroxide in situ; a cobalt source precursor and an iron source precursor are introduced, so that CoFe2O4 nanoparticles are preferentially generated in situ on the surface of the enrichment micro-area, and a hierarchical heterogeneous interface regulation and control area with local LLG / LDH / CoFe2O4 in sequential contact is formed. According to the invention, the problems of poor impedance matching and interface disorder caused by direct contact of magnetic particles and a carbon skeleton in the prior art are solved through a sequential control process, and impedance matching optimization, interface polarization enhancement and magnetic-dielectric cooperative loss are realized. When the matching thickness of the obtained composite material is 2.0 mm, the minimum reflection loss reaches-57.2 dB, the effective absorption bandwidth is 5.6 GHz, and the composite material has wide application prospects in the fields of wave-absorbing coatings, structural wave-absorbing patches, anti-electromagnetic radiation fabrics and the like.

The invention discloses a medium-entropy high-temperature dielectric ceramic and a preparation method thereof, and belongs to the technical field of functional ceramics, the chemical general formula of the ceramic material is (RE1, RE2, RE3) 3Al5O12, RE1, RE2 and RE3 are three different trivalent rare earth ions, and the key characteristic is that the ion radiuses of the three rare earth ions respectively belong to a large range, a medium range and a small range. According to the design, controllable maximum lattice distortion is introduced, the ion and electron polarizability of the material is remarkably enhanced on the premise that a garnet single-phase structure is not damaged, so that the intrinsic dielectric constant of the material is improved, and the medium entropy design ensures excellent high-temperature phase stability and dielectric property temperature stability of the material. The prepared medium-entropy high-temperature dielectric wave-absorbing ceramic can work in a high-temperature environment of 0-800 DEG C, not only has the characteristics of low heat conductivity and high temperature resistance, but also has excellent wave-absorbing performance in an X wave band, the lowest reflection loss of the medium-entropy high-temperature dielectric wave-absorbing ceramic can reach-58 GHz, and the effective absorption bandwidth of the medium-entropy high-temperature dielectric wave-absorbing ceramic can reach 2.8 GHz.

The invention discloses a preparation method of a high-entropy LDH / MXene aerogel composite wave-absorbing material, which comprises the following steps: (1) dissolving ferric salt, cobalt salt, nickel salt, manganese salt and copper salt in water, adjusting the solution to be alkaline, and performing hydrothermal reaction at high temperature to obtain high-entropy layered double hydroxide nanoflower dispersion liquid; (2) mixing the high-entropy layered double hydroxide nanoflower dispersion liquid with the single-layer MXene dispersion liquid, fully and uniformly stirring, pre-freezing, and performing bidirectional freeze-drying to form a three-dimensional aerogel composite structure; and (3) carrying out heat treatment in an inert atmosphere to obtain the high-entropy layered double hydroxide composite MXene aerogel wave-absorbing material. The prepared composite wave-absorbing material has the characteristics of radar wave broadband absorption and infrared band low emissivity, the effective absorption bandwidth larger than 4 GHz is achieved in the range of 2-18 GHz, the minimum reflection loss is lower than-48.82 dB, and meanwhile the emissivity in an infrared window of 8-14 microns is lower than 0.35.

The invention relates to a preparation method of a laser-infrared-radar compatible multispectral inhibition ceramic material, which comprises the following steps: by taking iron oxide, manganese oxide, magnesium oxide, copper oxide, nickel oxide and cobalt sesquioxide as raw materials, carrying out ball milling, mixing and drying, granulating, pressing into a green body sheet, and calcining to obtain a high-entropy ceramic substrate; depositing a low-refractive-index material L, a defect layer material S and a high-refractive-index material H on the high-entropy ceramic substrate according to a film layer structure as a substrate (LH) (LH) S (LH) Air or a substrate (LH) S (LH) (LH) (LH) Air by adopting a sputtering process; the prepared material has the multispectral protection characteristic compatible with laser / infrared / radar, and in the aspect of laser protection, the reflectivity can reach 2.19%, 1.78% and 2.9% at the characteristic laser points of 1.06 m, 1.54 m and 10.6 m; in the aspect of infrared protection, the reflectivity at the infrared absorption frequency bands of 3-5 m and 8-14 m can reach 97%; in the aspect of radar protection, under the ultra-thin 2.2 mm thickness, the effective absorption bandwidth of 3.2 GHz and the minimum reflection loss of-67.4 dB are achieved. The materials selected by the system are all high-temperature-resistant materials and can adapt to a high-temperature service environment.

The embodiment of the application discloses diamond-based composite wave-absorbing material; the method comprises the following steps: S1, the surface of nano-diamond particles is graphitized to obtain graphitized diamond composite particles; S2, the graphitized diamond composite particles are formed by molding to obtain a diamond-based composite wave-absorbing material blank; S3, the diamond-based composite wave-absorbing material blank is treated by high temperature and high pressure to obtain the diamond-based composite wave-absorbing material; the diamond-based composite wave-absorbing material has a minimum reflection loss value of -61.47 dB at 5.5 mm, the widest effective absorption bandwidth can reach 4.0 GHz at 2.7 mm, the Vickers hardness is between 40 and 60 GPa, the material is superhard, the normal temperature thermal conductivity is between 3.4 and 3.7 W / m*K, the initial oxidation temperature is between 1100 and 1250 DEG C, the corrosion current density is between 10 ‑6 ~10 ‑7 A / cm 2 , the self-corrosion potential is between -200 and 0 mV, the corrosion rate is between 0.001 and 0.005 mm / a, and the material is very corrosion resistant.