19 results about "Electromagnetic absorption" patented technology

This application discloses an electromagnetic absorber and an electromagnetic wave absorption method. The electromagnetic absorber includes: a reflective phase gradient metasurface array, comprising a first dielectric layer, a first metal backplate layer, and multiple metal resonant units. The first dielectric layer is disposed on the upper surface of the first metal backplate layer, and the multiple metal resonant units are arrayed on the first dielectric layer. Each metal resonant unit includes n metal H-shaped structures of different sizes. The reflective phase gradient metasurface array is used to convert plane waves into surface waves. A surface plasmon polariton coupler is used to converge and absorb the energy of the converted surface waves. This application can achieve effective convergence and absorption of surface wave energy.

The present application relates to the field of high-frequency microwave absorbing material and technology, disclose a kind of multifunctional electromagnetic material with high-frequency electromagnetic absorption and corrosion resistance characteristics and its preparation method and application, the multifunctional electromagnetic material is the core-shell structure with 10-100nm particle size, core is metal magnetic alloy component, shell layer is multilayer graphite carbon;It is obtained by carbonization treatment after dissolving and precipitating of metal salt, surfactant and organic ligand, the magnetic alloy component of core body in material and the graphite carbon matrix of shell layer form conductive network, conducive to the conduction loss caused by electron transition;Mutual hetero-interface is conducive to the interface polarization loss of electromagnetic wave.In addition, magnetic component provides strong magnetic loss, optimizes the impedance matching of wave-absorbing body, further enhances the attenuation ability to electromagnetic wave;And shell layer can effectively prevent the penetration and transmission of various corrosive media on the surface of target matrix, it is a kind of multifunctional electromagnetic material with high-frequency electromagnetic absorption and corrosion resistance characteristics.

A thermal interface material includes a matrix material; and a particulate filler dispersed in the matrix material, the particulate filler including particles that each include a first component and a second component, the first component exhibiting a native thermal conductivity value of greater than 10 W / m*K, wherein the thermal interface material exhibits a density of between about 1.5 g / cm3 to about 3 g / cm3, and an electromagnetic absorption value at 5 GHz of between -0.1 dB / mm and -100 dB / mm.

The invention discloses a manufacturing method of silicon carbide nanowire reinforced gallium indium liquid metal composite graphene oxide ultra-light electromagnetic absorption aerogel, and belongs to the technical field of wave-absorbing composite material manufacturing, and the manufacturing method comprises the steps of silicon carbide nanowire dispersion liquid preparation, liquid metal dispersion liquid preparation, composite hydrogel preparation and post-treatment. The preparation of the silicon carbide nanowire dispersion liquid comprises the following steps: adding silicon carbide nanowires into dimethyl sulfoxide, and carrying out ultrasonic treatment to obtain a SiCnw / DMSO dispersion liquid; the preparation of the liquid metal dispersion liquid comprises the following steps: adding gallium and indium liquid metal into dimethyl sulfoxide, then adding sodium alginate, and carrying out ultrasonic crushing treatment to obtain an SA / LM / DMSO solution. By reasonably designing the material composition and the preparation process, the material is ultra-light and has excellent electromagnetic wave absorption capacity, so that the requirement of the electromagnetic absorption field on a high-performance material is met.

A layered, highly absorptive electromagnetic shielding composite material and its preparation method involve selectively etching the Al layer of Ti3AlC2 to obtain an MX solution. Fe3O4 and MX are then assembled into a composite material, FM. Melamine foam is then carbonized to obtain a carbonized foam, CF. FM is then assembled onto a CF skeleton via an impregnation method to form a composite foam, FM@CF. Finally, MX is deposited on the bottom of FM@CF via vacuum filtration to form the layered, highly absorptive electromagnetic shielding composite material, FM@CF / MX. The preparation process is simple and easy to operate. The layered structure achieves a "low reflection-high absorption-high reflection-reabsorption" strategy for electromagnetic waves, successfully achieving a combination of high electromagnetic absorption and high electromagnetic shielding efficiency, significantly reducing secondary electromagnetic contamination and helping to address the hazards of electromagnetic radiation. This material is widely used in aerospace, military equipment, microelectronic devices, consumer electronics, and other fields.

An electro-absorption modulator 100 including a quantum well 102 configured to provide a variable electromagnetic absorption spectrum in response to an applied electric field, wherein the quantum well is a type-II quantum well comprising two material layers, each material layer having a graded material composition, such that the potential in each material layer varies as a function of position.

The film is of a layered structure, the middle of the film is an organic base material, the base material comprises a first surface and a second surface, and a transition layer, an electromagnetic absorption layer, an isolation layer, an electromagnetic reflection layer and a thermal radiation reflection layer are sequentially distributed on the first surface and the second surface. Meanwhile, penetrating through holes are distributed in the surface of the film, and conductive layers are attached to the inner walls of the through holes to communicate all the layers. The thin film utilizes the closed reflection effect of the electromagnetic reflection layer and the loss effect of the electromagnetic absorption layer, and the electromagnetic shielding effectiveness of the thin film in the wave band of 10 MHz to 10 GHz is larger than 80 dB; the hemispherical emissivity of the heat radiation reflecting layer on the outermost layer is 0.03-0.05, and the solar absorptivity is 0.09 + / -0.02. The preparation method of the thin film comprises the steps of substrate plasma modification, magnetron sputtering deposition of the multi-layer functional film, punching, vacuum evaporation plating of the heat radiation reflecting layer, annealing treatment and the like, and the process controllability is high. The thin film integrates the functions of electromagnetic shielding, thermal control, static prevention and heat dissipation, and has important application value in the field of aerospace equipment.

The invention relates to the technical field of photoelectric materials, in particular to an electromagnetic and infrared compatible flexible film material which is formed by sequentially arranging five layers of materials, and the five layers of materials sequentially comprise a metal film layer, an electromagnetic absorption layer, an electromagnetic transition layer, an infrared base film layer and an infrared low-emission layer from bottom to top. The electromagnetic / infrared compatible flexible film material prepared by the method provided by the invention is thin in thickness, light in weight and good in weather resistance, and is very suitable for reducing electromagnetic reflection and keeping low infrared emission performance at the same time.

The invention discloses a wave-absorbing structure and a wave-absorbing plate, the wave-absorbing structure comprises a skin layer, an impedance layer, a dielectric layer and a substrate layer which are stacked in sequence, the upper surface of the skin layer is an incident plane of electromagnetic waves, the impedance layer comprises a first conductive layer and a plurality of second conductive layers, the first conductive layer is square, and the second conductive layer is square. The plurality of second conductive layers are arranged around the outer side of the first conductive layer, and the second conductive layers are square rings with openings. The wave absorbing plate comprises M * N wave absorbing structures. Through reasonable design of a multi-layer composite structure, after electromagnetic waves are incident from the skin layer, multiple interference occurs between the impedance layer and the dielectric layer, and through the synergistic effect of absorption and reflection of the impedance layer and the substrate layer, efficient dissipation of electromagnetic energy is achieved, and the high-performance electromagnetic absorption effect is achieved. Besides, due to the design form of the open square ring of the second conductive layer, the impedance layer has an impedance compensation effect, the wave-absorbing bandwidth is effectively expanded, and particularly, a relatively wide effective absorption frequency band can still be kept in an oblique incidence state of electromagnetic waves.

The invention discloses a heat dissipation electromagnetic shielding film for spaceflight and a preparation method thereof, the prepared film is of a multi-layer structure, and a transition layer, an electromagnetic absorption layer, an isolation layer, an electromagnetic reflection layer and a thermal radiation reflection layer are sequentially arranged on a first surface of a base material; an electromagnetic reflecting layer, a heat radiation reflecting layer, a heat radiation layer and an anti-static layer are sequentially arranged on the second surface of the conductive base material; through holes are distributed in the surface of the electromagnetic shielding film; metal coatings are attached to the inner walls of the through holes, and all layers of the thin film are communicated through the metal coatings. The anti-static layer is prepared by sequentially sputtering the electromagnetic reflecting layer on the second surface of the base material, depositing the thermal radiation reflecting layer through vacuum evaporation, then coating the thermal radiation layer and curing, and coating conductive liquid or in a magnetron sputtering mode. The second surface of the electromagnetic shielding film has low solar absorptivity and high hemispherical emissivity, the solar absorptivity is less than or equal to 0.40, the hemispherical emissivity is not less than 0.60, and the electromagnetic shielding film has a good heat dissipation function and adapts to harsh application scenes in the aerospace field.

The application discloses a full-metal electromagnetic absorption structure for eliminating the influence of multipath effect on a course beacon system, and belongs to the technical field of aviation.The full-metal electromagnetic absorption structure comprises a metal back plate, an intermediate air layer and an upper resonant layer which are arranged in layers from bottom to top; the upper resonant layer is composed of periodically arranged resonant units; each resonant unit is composed of four square metal radiation patches with fan-shaped hollows; the outer ring of each square metal radiation patch is connected by a lumped capacitance element, and the internal cross structure is connected by a lumped resistance element; each resonant unit is provided with a first pin interface at each corner, and a second pin interface is arranged at the center of each resonant unit, wherein the pins at the four corners of each unit are connected with the metal back plate through a metal column.The full-metal electromagnetic absorption structure solves the problem that the course beacon system is subjected to multi-angle and multi-direction interference signal incidence in a complex multi-obstacle environment, and effectively eliminates the influence of multipath effect on the course beacon system.

The invention discloses a lightweight broadband electromagnetic absorption composite material and a preparation method thereof. The lightweight broadband electromagnetic absorption composite material is a graded magnetoelectric network formed by a three-dimensional porous carbon skeleton with a hierarchical pore structure and iron-nickel alloy nanoparticles; the three-dimensional porous carbon skeleton is a three-dimensional porous carbon skeleton with a hierarchical pore structure, which is formed after delignification treatment by taking natural balsa wood as a biological template, and retains a directional conduit structure of the natural balsa wood; iron-nickel alloy nanoparticles are loaded in channels and on the surfaces of hole walls of the three-dimensional porous carbon skeleton in situ. The method is particularly suitable for radar wave-absorbing interlayers, electromagnetic compatibility panels and aerospace stealth structures.

Radar retroreflective (R3) devices including an electromagnetic absorber are provided. The electromagnetic absorber is disposed on selected areas of the device to reduce specular reflection without substantially reducing retroreflection of the device.

The invention discloses a preparation method of a multiband photoelectric compatible absorbing material based on dysprosium-doped garnet ferrite, and belongs to the technical field of photoelectric functional materials. The invention aims to solve the problems that an existing material with a single function is difficult to meet performance requirements in complex electromagnetic and optical environments, and cross-spectrum collaborative response is difficult to realize. According to the invention, the f-f transition characteristic of Dy < 3 + > is combined with the lattice regulation and control of garnet ferrite, so that magnetoelectric synergistic loss is realized; the magnetic moment density of the material is remarkably improved through the high spin-orbit coupling effect of Dy < 3 + >, meanwhile, a specific laser echo signal can be effectively restrained through a wide-area near-infrared absorption band of the material, and ferrite serves as a carrier and a chromaticity regulator. The invention realizes the multiband compatible absorption effect, and is suitable for electromagnetic absorption, optical protection and environment fusion scenes, such as the fields of intelligent optical coatings and the like.

A method of correcting amplitude variations in the output of a spectrometric instrument (300) due to variations in the optical path length (L) through a sample holder (600), the method comprising: exposing a sample in a sample holder (600) to electromagnetic radiation at a plurality of wavenumbers; detecting electromagnetic absorption intensities in the sample at the plurality of wavenumbers; providing the detected absorption intensities indexed for the wavenumbers to a computer device (510) as spectral data; and applying a mathematical transformation (Icorr) to the spectral data in the computer device (510) to correct for amplitude variations in the output of the spectrometric instrument (300), and correcting for amplitude variations by determining a difference (Δ(SB)) between absorbance values at a first derivative of spectral data from a sample of zero material (SBZl) at two different wavenumber ranges. Z ) / ) to calculate the mathematical transformation; and calculating as the difference (Δ(SB Z ) / ) is the mathematical transformation of the inverse correlation function (Icorr).

The invention provides an environment-friendly carbon-based foaming aqueous solution stealth agent as well as a preparation method and application thereof, and belongs to the field of special functional materials. The carbon-based foaming aqueous solution comprises an electromagnetic absorbent, a surfactant, an auxiliary agent and water, an ultrasonic emulsification technology is adopted, two surfactants with complementary advantages are compounded, a light carbon-based electromagnetic wave absorbent is introduced, meanwhile, a stabilizer, a foaming agent, a solubilizer and other auxiliaries are combined to achieve comprehensive regulation and control of a system, and the infrared / visible light / radar multi-spectrum compatible stealth carbon-based foaming aqueous solution is prepared. The foaming aqueous solution effectively improves the stability of bubbles, the bubbles produced by a foaming machine can stably hover for more than 40 minutes, and favorable guarantee is provided for improving the battlefield viability of marine equipment such as ships and the like. The carbon-based foaming aqueous solution takes water as a dispersion medium, and has the advantages of safety, environmental protection, long duration and the like.

The invention relates to a hydrogel-based wave-absorbing material regulated and controlled through electrochemistry, and belongs to the technical field of flexible electronic and electromagnetic functional materials. The adjustable electromagnetic absorption device based on the interdigital electrode-hydrogel composite structure comprises a metal reflecting layer, a conductive hydrogel layer arranged on the metal reflecting layer and an interdigital electrode pattern constructed on the surface of hydrogel. The conductive hydrogel is doped with graphene oxide and multivalent metal ions, so that the conductivity and polarization capability of the conductive hydrogel are enhanced; the electrode pattern is made of a copper nano material, and a periodic interdigital structure is formed on the surface of the hydrogel by using an ultrasonic spraying technology. A low-voltage electric field is loaded through an electrode, the complex dielectric constant (real part and loss) of the hydrogel is regulated and controlled, and the absorption performance of incident electromagnetic waves is dynamically adjusted. Compared with a traditional wave-absorbing structure, the wave-absorbing structure has good flexibility, light weight and electronic speed control response capability, is suitable for the fields of flexible electronics, wearable equipment, electromagnetic shielding and the like, and has wide application prospects.

The application discloses a preparation method of a flower-shaped Au@Fe3O4 / C nano composite wave-absorbing material, and comprises the following steps: S1, using a gold nanoparticle solution, acetylacetone iron and a first organic solvent as raw materials, a one-step synthesis method is adopted to prepare the flower-shaped Au@Fe3O4 nanoparticle; and S2, using the obtained flower-shaped Au@Fe3O4 nanoparticle as a precursor and dicyandiamide as a carbon source to prepare the Au@Fe3O4 / C nano composite wave-absorbing material. The preparation method of the Au@Fe3O4 / C nano composite wave-absorbing material has the following advantages: firstly, the prepared Au@Fe3O4 nanoparticle is an ionic nanoporous organic network polymer; the intervention of the gold nanoparticle improves the dielectric property of the Au@Fe3O4 / C material; the Au@Fe3O4 nanoparticle has a rich hetero-interface structure and a large specific surface area, which amplifies the'surface effect' of the bulk material; the electromagnetic wave can be reflected and scattered multiple times in the flower-shaped Au@Fe3O4 / C material and continuously attenuated; the material has a wide effective electromagnetic absorption performance and can be applied to the field related to radar stealth.