19results about How to "Absorption Bandwidth" patented technology

The invention belongs to the technical field of wave absorption, and provides a variable-wall-thickness composite material honeycomb interlayer wave-absorbing structure and an integrated preparation method thereof. The core structure in the middle wave-absorbing layer is composed of a plurality of variable-wall-thickness unit cell cores arranged in an array mode, the reflection frequency of electromagnetic waves in the structure can be increased, the electromagnetic wave absorption frequency band is widened, and the electromagnetic wave absorption loss is improved. The reflecting layer of the interlayer wave-absorbing structure is prepared from a composite material composed of conductive continuous fibers and high-performance thermoplastic resin, the wave-transparent layer is prepared from a composite material composed of low-dielectric-constant continuous fibers and high-performance thermoplastic resin, and the core layer is prepared from thermoplastic high-performance resin containing magnetic loss and electrical loss wave-absorbing agents. The preparation method is easy to operate, the process is stable, raw materials are wide, integrated overall printing of the complex sandwich wave-absorbing structure can be achieved, and good application prospects are achieved.

The invention discloses a broadband ultra-wide-angle metamaterial wave absorber and application, and belongs to the field of electromagnetic wave absorption. The broadband ultra-wide-angle metamaterial wave absorber is formed by periodically arranging a plurality of wave absorber units; each wave absorber unit sequentially comprises a metal layer, a first high-resistance surface layer, a dielectric layer, a lumped element layer and a second high-resistance surface layer from bottom to top; each of the first high-resistance surface layer and the second high-resistance surface layer is of a dielectric structure with a high-resistance surface coating on the surface; the lumped element layer is composed of a metal and a resistor. The lumped element and the high-resistance surface are combined, the broadband wave-absorbing characteristic and the wide-angle wave-absorbing characteristic are both considered, the wave-absorbing performance in a TE polarization state is enhanced by adopting the non-centrosymmetric design, the design process is simplified, the structure is simple, the cost is low, and the wide application prospect is achieved.

The invention provides a composite wave-absorbing material as well as a preparation method and application thereof, and relates to the technical field of wave-absorbing materials. The composite wave-absorbing material provided by the invention has high-entropy ferrite with a spinel structure and high-entropy iron alloy with a body-centered cubic structure, the chemical formula of the high-entropy ferrite is (CoxNiyCuzMnaZnbMgcCrd) Fe2O4, x + y + z + a + b + c + d = 1, x, y and z are real numbers greater than 0 and less than 1, a, b, c and d are real numbers greater than or equal to 0 and less than 1, and two or three of a, b, c and d are equal to 0. The composite wave-absorbing material provided by the invention has the advantages of thin matching thickness, strong wave-absorbing performance and wide absorption frequency band.

The invention relates to a multi-absorption-band ultra-wideband common-mode filter based on a mixed resonator structure. The multi-absorption-band ultra-wideband common-mode filter comprises a coupling microstrip line, a dielectric substrate, a main resonator, an auxiliary resonator and a resistor, the filter has an upper surface and a lower surface, and a coupling microstrip line comprises a metal conduction band located on a dielectric substrate and a metal ground layer located below the dielectric substrate; two ends of the coupling microstrip line are respectively connected with the input port and the output port; the main resonator is etched in the middle of the metal ground layer; the auxiliary resonator is etched on the outer side of the main resonator in the metal ground layer; the coupling microstrip line is mutually coupled with the main resonator and the auxiliary resonator to realize mixed resonance; the resistor crosses the gap of the auxiliary resonator at the intersection of the auxiliary resonator and the symmetric line, and the two ends of the resistor are connected with the metal ground layers inside and outside the metal conduction band; according to the invention, the ultra-wideband common-mode suppression bandwidth and a plurality of absorption bands are provided, and the absorption bands dissipate common-mode noise in the form of heat energy, so that the problem of potential common-mode electromagnetic interference in the system is reduced, and normal transmission of differential-mode signals is not damaged at the same time.

The present invention provides a FeNiHo / carbon nanofiber composite absorber and a preparation method thereof, an absorbent material and a preparation method thereof, and belongs to the technical field of electromagnetic wave absorbing materials. The present invention first mixes iron salt, nickel salt, holmium salt and polyvinyl pyrrolidone in a mixed solvent, and electrostatically spins the obtained spinning precursor solution to obtain a nanofiber membrane; the nanofiber membrane is sequentially subjected to pre-oxidation treatment and carbonization treatment to obtain a FeNiHo / carbon nanofiber composite absorber. The FeNiHo / carbon nanofiber composite absorber, paraffin and petroleum ether are mixed, and then pressed and irradiated with ultraviolet light to obtain an absorbing material. The FeNiHo alloy nanoparticles in the composite absorber improve the impedance matching performance and electromagnetic wave attenuation ability of the carbon nanofiber. The obtained absorbing material can achieve the purpose of real-time adjustment of the absorption frequency by irradiation with ultraviolet light.

The invention provides a middle and far infrared broadband metamaterial absorber and a design method thereof. The middle and far infrared broadband metamaterial absorber comprises metamaterial absorption units which are arranged in a periodic array mode. The whole metamaterial absorption unit is square and comprises a top metal layer, a dielectric layer and a bottom metal layer from top to bottom in sequence. The top metal layer is attached to the upper surface of the dielectric layer and is formed by arranging eight metal sheets according to a certain arrangement mode, namely a circular metal sheet which is arranged at the central position of the upper surface of the dielectric layer, and the center of the circular metal sheet is aligned with the center of the upper surface of the dielectric layer; three annular metal sheets concentric with the circular metal sheet surround the periphery of the circular metal sheet, and gaps exist between the circular metal sheet and the annular metal sheet on the innermost layer and between the annular metal sheets on the adjacent layers from inside to outside. And the four metal square sheets with the same size are respectively arranged at four corners of the upper surface of the dielectric layer. The absorption bandwidth is greatly prolonged, and perfect absorption of a target wave band can be infinitely approached by adjusting geometric parameters of the absorber.

The invention provides a metamaterial broadband microwave absorber which comprises a metal bottom plate and a dielectric layer located above the metal bottom plate, and a plurality of semiconductor periodic structure units are periodically laid and arranged on the upper surface of the dielectric layer; each semiconductor periodic structure unit comprises a segmented ring-shaped structure and a cross-shaped structure which are connected with each other; the segmented circular ring structure comprises at least three segmented circular rings which are concentrically arranged and have different radiuses; each segmentation circular ring is divided into four arc pairs which are symmetrically distributed by a cross-shaped structure; the metal bottom plate is made of a conductive metal material; the dielectric layer is made of an insulating electrolyte material; and the product of the thickness and the conductivity of the semiconductor periodic structure unit is a fixed value. By adopting the metamaterial absorber, the problems of narrow band and polarization sensitivity in the existing metamaterial absorber can be relieved.

The utility model relates to the technical field of sound barriers, and discloses a road sound barrier with a wind-resistant structure, which comprises a noise reduction barrier, a top cover is mounted and connected on the outer top surface of the noise reduction barrier, silencing holes are arranged on the noise reduction barrier, a support plate is mounted and connected on one side of the outer surface of the noise reduction barrier, and a base is fixedly mounted at one end of the support plate far away from the noise reduction barrier. Mounting strips are fixedly connected to the two sides of the outer surface of the base, a wind resistance block is mounted and connected to one side of the outer surface of the noise reduction barrier, sound absorption cotton is mounted and connected to one side of the outer surface of the noise reduction barrier, a pressing plate is connected to one side of the outer surface of the sound absorption cotton, and a connecting rod is fixedly connected to one side of the outer surface of the pressing plate. The base and all components fixed on the outer top surface of the base are pressed through the gravity of the gravity piers, the gravity piers are arranged inside for stabilization, the supporting plates are arranged outside for reinforcement, the isosceles triangle design of the supporting plates has high stability for resisting strong wind, and the wind resistance blocks can greatly reduce the wind resistance of the device.

The invention provides a wave-absorbing honeycomb material and a preparation method thereof. The wave-absorbing honeycomb material comprises an aramid paper honeycomb substrate, and a foam absorbing layer, an optional foam transition layer and a foam matching layer which are sequentially arranged in honeycomb holes of the aramid paper honeycomb substrate from outside to inside, wherein the dielectric constant of the foam matching layer is gt; the dielectric constant gt of the foam transition layer; the foam absorbs the dielectric constant of the layer. According to the wave-absorbing honeycomb material, the technical effects of improving the broadband absorbing effect and reducing the thickness are achieved.

The wave-absorbing foam prepreg comprises a pure resin adhesive film layer, a wave-absorbing foam layer with a double-foam structure and a wave-absorbing adhesive film layer, wherein the double-foam structure of the wave-absorbing foam layer with the double-foam structure is resin foam and pure electromagnetic matrix foam; the wave-absorbing adhesive film is a resin adhesive film added with a magnetic wave-absorbing agent or a dielectric wave-absorbing agent; and the resin adhesive film layer and the wave-absorbing adhesive film layer are made of the same resin. The invention also discloses a preparation method and application thereof. The wave-absorbing foam prepreg adhesive film provided by the invention has the advantages of good surface integrity, controllable adhesive film thickness, strippable processing, good resin processability, strong electromagnetic wave absorption capability, excellent use performance and wave-absorbing performance, and can be applied to the fields of aerospace, communication, electronic equipment, confidential building materials, shoe rubber soles and the like.

The invention relates to a method for preparing a SiC-based porous material, in particular to a method for preparing a SiC-based porous material from balsa wood and lignite. The invention aims to solve the problems that the existing SiC-based porous material is high in preparation cost and difficult to prepare, and the functions of high heat insulation, high wave absorption and electromagnetic protection are difficult to consider at the same time, and the problem of low utilization rate of lignite is solved. The preparation method comprises the following steps: 1, carrying out ball-milling mixing and sieving treatment on the lignite, the adhesive, the dispersing agent and the deionized water; secondly, the blocky balsa wood is placed in the mixed slurry and subjected to vacuum impregnation; 3, freeze drying and carbonization; and 4, carbon thermal reduction. The method is used for preparing the SiC-based porous material from the balsa wood and the lignite.

The invention relates to a thermal spraying composite ceramic powder material as well as a preparation method and application thereof, belongs to the technical field of high-temperature electromagnetic functional ceramic materials, and solves the problems that an existing electromagnetic functional material is narrow in absorption frequency band, low in absorption loss, poor in temperature resistance, poor in cohesive bonding strength, poor in bonding force with a substrate and easy to fall off. The composite ceramic material comprises a base material and a functional material, the base material is mullite and the like, and the functional material comprises SiBCNFe, Ti3SiC2, CNTs, MoSi2, ZnO and YSZ. The multifunctional material has multiple loss mechanisms, widens the electromagnetic wave absorption frequency band, improves the absorption loss and undertakes the controllability of the electromagnetic function; by controlling the size, density and sphericity of the material, the cohesive bonding strength and fluidity of the material are improved, the porosity of the prepared coating is reduced, and the compactness and mechanical property of the coating are improved; in addition, the various electromagnetic functional materials are temperature-resistant materials, so that the expansion of a preparation process and an application environment of the composite ceramic material is facilitated.

The application discloses a carbon-composite high-entropy metal oxide electromagnetic functional material and a preparation method thereof, and relates to the technical field of microwave absorbing materials. The electromagnetic functional material is composed of (Fe 0.2 Co 0.2 Ni 0.2 Mn 0.2 Cr 0.2 )3O4 / C, and the preparation method comprises the following steps: adding equimolar iron salt, cobalt salt, manganese salt, chromium salt and nickel salt into water together with urea, polyvinylpyrrolidone and a carbon source to configure a mixed solution, then heating and reacting, centrifuging and drying the reaction product after the reaction is completed, and obtaining the electromagnetic functional material. By introducing the carbon material with high dielectric constant, the electric conduction performance and the electric loss performance are enhanced, the impedance matching is optimized, the overall density is reduced, the absorption bandwidth is widened, the effective absorption bandwidth covers the full wave band of 2-18GHz, the electromagnetic functional material is suitable for multi-wave bands, and the problems of low absorption rate and narrow frequency band are solved. Moreover, the preparation process is simple, and the one-time hydrothermal reaction can be completed, so that the scale production is facilitated.

This invention discloses a dielectric-magnetic synergistic loss type electromagnetic wave absorbing material, its preparation method, and its application. The dielectric-magnetic synergistic loss type electromagnetic wave absorbing material of this invention comprises rGO aerogel and Ni distributed in the rGO aerogel. x Co 1‑x Fe2O4 magnetic nanoparticles x The range of values ​​for is 0≤ x ≤1. The preparation method of the dielectric-magnetic synergistic loss type electromagnetic wave absorbing material of the present invention includes the following steps: mixing graphene oxide and Ni x Co 1‑x Fe2O4 magnetic nanoparticles are dispersed in water, then subjected to a hydrothermal reaction, followed by freeze-drying. The dielectric-magnetic synergistic loss-type electromagnetic wave absorbing material of this invention possesses advantages such as low density, small matching thickness, wide absorption bandwidth, high absorption intensity, and flexible adjustment of composition and properties, making it a promising candidate for applications in radar stealth and electromagnetic protection.

The utility model relates to the technical field of textiles, and discloses a sound-absorbing carpet and a vehicle. The sound-absorbing carpet sequentially comprises a lower layer (1), a gradient density fiber felt layer (2) and an upper hard layer (3) from bottom to top, the density of the gradient density fiber felt layer (2) is sequentially increased from bottom to top, and the density of the gradient density fiber felt layer (2) is smaller than that of the fiber felt layer (3). According to the sound-absorbing carpet, the low-frequency sound-absorbing capability of the automobile carpet can be improved, and wide range and strong sound absorption are realized.

The application provides a magnetic metal powder / porous carbon composite material, a preparation method and application thereof. The preparation method comprises the following steps: step S1, performing surface oxidation reaction on a magnetic carbonyl metal powder to form pretreated metal powder; step S2, dissolving a copolymer PS n -b-PEO m in a first solvent, adding a mixed solution of ethanol and water into the first solvent to obtain a milk emulsion; step S3, adding the pretreated metal powder, pyrrole and FeCl3 into the milk emulsion to perform in-situ polymerization reaction, so as to form a precursor and obtain a precursor solution; step S4, removing the spherical PS n -b-PEO m micelles in the precursor by a solvothermal method, and then drying to obtain a porous precursor; and step S5, calcining the porous precursor under an inert atmosphere to obtain the magnetic metal powder / porous carbon composite material. The magnetic metal powder / porous carbon composite material prepared by the application has better wave absorption performance in a low frequency band.

The invention discloses a NiCo-MOF derived carbon nanotube wave-absorbing material with a core-shell structure and a preparation method of the NiCo-MOF derived carbon nanotube wave-absorbing material, and relates to the technical field of wave-absorbing materials. According to the method, NiCo-MOF with a core-shell structure is obtained by controlling the solvent proportion, then a carbon nano tube grows on the surface of the NiCo-MOF in situ, the prepared MOF-derived carbon nano tube has a hollow core-shell structure, and the surface of the MOF-derived carbon nano tube is covered with a layer of dense carbon nano tube. By adopting the structure, the conductivity of the material is greatly improved, the types of interface polarization are enriched, and good wave absorbing performance is shown in the frequency band of 2-18 GHz; the hollow structure is beneficial to multiple reflection of electromagnetic waves inside, and when the matching thickness is 2.5 mm, the effective absorption bandwidth can reach 5.7 GHz, and the minimum absorption peak reaches 4.8 GHz. The method is simple in technological process, low in cost and suitable for large-scale preparation, and has wide application prospects in the fields of light broadband wave absorption, thermal protection and the like.

This invention belongs to the field of coloring pigments and their preparation technology, specifically relating to an ion-absorbing silicate coloring pigment. The general formula of its initial raw materials is: x AX 1 / δ · m MX 2 / δ · n SiX 4 / δ · y REX 2或3 / δ A carbon source is added, and the mixture is calcined at 900-1500℃ in an inert or reducing atmosphere for 1-50 h to obtain an ion-absorbing silicate coloring pigment. The resulting pigment can achieve continuous coloring in the blue-green to red-orange visible light region under sunlight. This ion-absorbing silicate inorganic coloring pigment is non-toxic, exhibits strong absorption in the blue-green light region with a wide absorption band, and overcomes the shortcomings of the aforementioned functional luminescent pigments, such as weak light absorption, extremely poor coloring performance, and unstable coloring. It also possesses many advantages that make it an ideal coloring pigment, including abundant and inexpensive raw materials, stable physicochemical properties, simple synthesis conditions, good compatibility with glass and ceramics, and environmental friendliness during preparation and use.

The present application relates to the field of magnetic material technology, and provides a broadband wave absorbing plate, including a first wave absorbing material layer, a second wave absorbing material layer, a third wave absorbing material layer, and a fourth wave absorbing material layer stacked sequentially from bottom to top, wherein the upper surface of each layer of the first wave absorbing material layer, the second wave absorbing material layer, and the third wave absorbing material layer is provided with a plurality of micro-prisms, and the upper surface of each layer of the first wave absorbing material layer, the second wave absorbing material layer, the third wave absorbing material layer, and the fourth wave absorbing material layer is provided with a plurality of micro-holes; wherein the magnetic permeability of the first wave absorbing material layer, the second wave absorbing material layer, the third wave absorbing material layer, and the fourth wave absorbing material layer decreases sequentially. The present application adopts a multi-layer wave absorbing material composite design, and its electromagnetic parameters increase sequentially from the outermost absorption interface to the inner side, which can enhance the absorption of electromagnetic waves and reduce the reflection ratio. The micro-prisms and micro-holes designed on the upper surface of the wave absorbing material can also enhance scattering and reduce reflection, thereby achieving ‑20dB absorption under low thickness conditions.