61 results about "Electromagnetic wave absorber" patented technology

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 relates to a hydrogel with both strength and electromagnetic wave absorption and a preparation method thereof. The preparation method of the hydrogel material comprises the following steps: S1, carrying out amination treatment on Fe3O4; s2, adding Fe3O4-NH2 and GO in the step S1 into deionized water, and carrying out ultrasonic dispersion; s3, adding polyethylene glycol methyl ether acrylate-480 and acryloyl morpholine into the dispersion liquid in the S2, and dissolving the polyethylene glycol methyl ether acrylate-480 and the acryloyl morpholine to obtain a mixed liquid; s4, removing dissolved oxygen in the mixed solution in S3, sealing the container, and stirring under an ice bath condition; s5, adding potassium persulfate and N, N, N ', N'-tetramethylethylenediamine into the mixed solution stirred in the step S4, and closing the container again; s6, the container is subjected to a polymerization reaction at the temperature of 60 DEG C, and hydrogel is obtained. Compared with the prior art, when the thickness of the hydrogel material is 2.07 mm, strong broadband microwave absorption is achieved, RLmin is-57.0 dB, EABmax is 6.4 GHz, meanwhile, excellent flexibility is kept, and the work provides a new view angle for developing a high-flexibility and efficient electromagnetic wave absorber.

To provide an electromagnetic wave absorption body capable of obtaining satisfactory electromagnetic wave absorption characteristics in "Low / Mid bands", a composition for electromagnetic wave absorption body molding for forming the same, and a composite filler for electromagnetic wave absorption body molding.SOLUTION: Disclosed is a composition for electromagnetic wave absorption body molding including: a polymer containing at least an acrylic acid ester copolymer as a main component; and a composite filler comprising a conductive filler which is coated with silicon oxide, consequently, formed with a an insulating membrane, wherein the conductive filler is kneaded in the polymer into a dispersion state and contains at least one kind of carbon material selected from among a carbon micro coil, a carbon nano fiber, a carbon nano tube and active carbon. Further disclosed is an electromagnetic wave absorption body which is made of the composition for electromagnetic wave absorption body molding through molding and hardening in a state where the composite filler is dispersed in the polymer.SELECTED DRAWING: Figure 1

The electromagnetic wave absorber has a three-dimensional network structure of conductive fibers and is used for absorbing terahertz waves.

A method for preparing a ferrite solid waste-based electromagnetic wave absorbing material, relating to the field of electromagnetic wave absorbing materials, involves first purifying the ferrite solid waste, then surface-modifying it using a silane coupling agent KH550. Next, MoS2 nanoparticles and the surface-modified ferrite solid waste particles are ball-milled using a high-energy ball mill to obtain a composite electromagnetic wave absorber. The composite electromagnetic wave absorber is then granulated, pressed, and heat-treated to obtain a preform. Finally, the preform is processed to obtain an electromagnetic wave absorbing material of a specific shape. This invention first surface-modifies the purified ferrite solid waste particles, then composites them with molybdenum disulfide through a ball milling process. This preparation process allows for the complementary advantages of the two materials, resulting in an electromagnetic wave absorbing material with higher mechanical properties and superior electromagnetic wave absorption performance.

To provide a resin composition having high absorptivity of electromagnetic waves and having low transmittance and reflectivity of electromagnetic waves, which is a resin composition for an electromagnetic-wave absorber having small difference in reflectivity due to the difference in frequency of electromagnetic waves and an electromagnetic-wave absorber.SOLUTION: There is provided a resin composition for an electromagnetic-wave absorber which comprises 0.1 to 10.0 pts.mass of a carbon nanotube based on 100 pts.mass of a thermoplastic resin, wherein when the resin composition is molded into 150 mm×150 mm×2 mm thickness, the absorptivity determined by the expression (A) in the frequency of 76.5 GHz is 40.0 to 100%, and when the resin composition is molded into 150 mm×150 mm×2 mm thickness, the difference between the highest value and the lowest value of the reflectivity determined by the expression (B) in the frequency of 70 to 80 GHz is 20.0% or less.SELECTED DRAWING: None

The electromagnetic wave absorber comprises a matching impedance layer, a temperature control phase change resonance layer, a magnetic control phase change regulation and control layer and a metal reflection layer which are sequentially stacked, wherein the temperature-control phase-change resonance layer comprises a base body layer, a plurality of temperature-control phase-change units which are periodically arranged on the base body layer, and a heating layer which is attached to the surface of one side of the base body layer; the heating layer is used for adjusting the temperature of the temperature control phase change unit, so that the conductivity of the temperature control phase change resonance layer is changed; the magnetic control phase change regulation and control layer comprises a magnetic control coil and magnetic control phase change units which are periodically arranged; the magnetic control coil is used for applying magnetic fields with different sizes to the magnetic control phase change unit, so that the magnetic conductivity of the magnetic control phase change material structure is changed; and the arrangement period sizes of the temperature control phase change units and the magnetic control phase change units are between nanometer magnitude and millimeter magnitude. According to the electromagnetic wave absorber, the wave absorbing frequency capable of absorbing waves can be switched and adjusted within a larger range, and therefore the requirements of various different application scenes can be better met.

The application discloses a kind of PEI or PEEK-based 3D printing wave-absorbing materials and preparation method thereof.The 3D printing wave-absorbing material includes the following components by mass fraction: polyetherimide resin or polyether ether ketone resin: 45~65 parts;Electromagnetic wave absorber: 10~50 parts;Impact modifier: 4~12 parts;Flow aid: 2~8 parts;Antioxidant: 0.5~3 parts;Wherein, the electromagnetic wave absorber includes magnetic absorber and carbon-based absorber, the impact modifier and the carbon-based absorber are pre-coated to form the carbon-based absorber coated with the impact modifier on the surface, and the magnetic absorber is surface modified by silane coupling agent.The application significantly improves the mechanical properties and thermal stability of the material by using specific raw material composition and combining specific multi-layer co-extrusion and online heat treatment process.The preparation process is simple and easy to operate, and is suitable for industrial continuous production.

To provide a resin composition that has a high electromagnetic wave absorption rate, a molded body, an electromagnetic wave absorber, and a method for manufacturing the resin composition.SOLUTION: A resin composition contains a polybutylene telephthalate resin, a polystyrene resin, and carbon nanotubes. There are also provided a molded body of the resin composition, and an electromagnetic wave absorber, and a method for manufacturing the resin composition.SELECTED DRAWING: None

To provide an electromagnetic wave absorber that can improve electromagnetic wave absorption performance. [Solution] The electromagnetic wave absorber according to the present invention includes a plurality of sheets comprising glass fibers and a conductive carbon material, the plurality of sheets being laminated, the first sheet of the plurality of sheets being provided on the incident surface side to which electromagnetic waves are incident, and the surface resistivity of the first sheet is higher than that of the second sheet.

The present invention provides a ferrite powder which contains 0.9% by mass to 2.5% by mass of lithium (Li), 1.0% by mass to 8.0% by mass of manganese (Mn), and 58.0% by mass to 69.5% by mass of iron (Fe), and has a crystal phase belonging to the space group P4132 and a crystal phase belonging to the space group Fd-3m. In the X-ray diffraction profile, the half width of the (311) plane of the crystal phase belonging to the space group Fd-3m is 0.09° to 0.22°, and the volume average particle diameter D50 is not less than 1 μm but less than 20 μm.

To provide a resin composition, a pellet, a molding, an electromagnetic wave absorber and a method for producing a resin composition, which have high electromagnetic wave absorption rates.SOLUTION: A resin composition contains, with respect to 100 pts.mass of a polyester resin having intrinsic viscosity of 0.87-2.00 dL / g, 0.1-10.0 pts.mass of a polyamide resin, and carbon nanotube.SELECTED DRAWING: None

An electromagnetic wave absorber (1) includes a dielectric layer (10), a resistive layer (20), and an electrically conductive layer (30). The resistive layer (20) is disposed on one principal surface of the dielectric layer (10). The electrically conductive layer (30) is disposed on the other principal surface of the dielectric layer (10) and has a sheet resistance lower than a sheet resistance of the resistive layer (20). The resistive layer (20) has a sheet resistance of 200 to 600Ω / □. When the resistive layer (20) is subjected to an immersion treatment in which the resistive layer (20) is immersed in a 5 weight % aqueous solution of NaOH for 5 minutes, an absolute value of a difference between a sheet resistance of the resistive layer (20) before the immersion treatment and a sheet resistance of the resistive layer (20) after the immersion treatment is less than 100Ω / □.

The invention discloses a periodic embedded multilayer composite frustum electromagnetic wave absorber, which belongs to the technical field of electromagnetic wave absorption and stealth, and comprises a metal plate and a wave absorbing structure, the wave-absorbing structure comprises a substrate layer and a plurality of multi-layer frustum wave-absorbing units. The substrate layer covers the metal plate; the multi-layer frustum wave absorbing unit is arranged on the substrate layer; the multi-layer frustum wave-absorbing unit is of a frustum structure formed by nesting a plurality of wave-absorbing layers from outside to inside; the substrate layer and each wave absorbing layer of the multi-layer frustum wave absorbing unit are made of electromagnetic wave absorbing materials, and the electromagnetic wave absorbing materials comprise a wave absorbing agent and a base material; in the multi-layer frustum wave-absorbing unit, the impedance of the plurality of wave-absorbing layers is gradually reduced in a gradient manner from outside to inside. The electromagnetic wave absorber has the characteristics that the structure is simple, structural parameters are easy to regulate and control, electromagnetic wave absorption is broadband and efficient, and polarization and polarization are insensitive.

The application discloses a preparation method of a rhombic dodecahedron cavity structure electromagnetic wave absorber Fe / ZnO@C, and belongs to the technical field of composite materials, and comprises the following steps: firstly, synthesizing magnetic Fe3O4 particles; then, preparing a precursor Fe3O4@ZIF-8; coating the surface of the Fe3O4@ZIF-8 with polydopamine to obtain Fe3O4@ZIF-8@PDA; and finally, obtaining a rhombic carbon shell coated zinc-iron alloy through high-temperature carbonization treatment. The Fe / ZnO@C composite with a rhombic dodecahedron cavity structure is prepared by using a three-step method, and has excellent electromagnetic wave absorption performance. The preparation process is simple, and the method is suitable for large-scale production; and the material structure is novel, the density is relatively small, and the product has excellent performance.

To provide a signal transmitter / receiver capable of achieving both target detection performance and reduction of erroneous detection.SOLUTION: A signal transceiver comprising: a control circuit; an antenna body including an antenna element group that is an assembly of a plurality of antenna elements; and an electromagnetic wave absorber, wherein the electromagnetic wave absorber and the antenna body have all of the following features 1 to 3. Feature 1: An angle φ formed between the electromagnetic wave absorber and the antenna body surface is π / 4 or more and 3 π / 4 or less. Feature 2: An electromagnetic wave absorber is installed toward an electromagnetic wave transmission direction of the antenna body surface. Feature 3: The following expressions 1 and 2 are satisfied, where A (k) is a return loss at a peak top when an electromagnetic wave is incident on the electromagnetic wave absorber from the antenna body at an incident angle k, and θ is an angle formed by a traveling direction of the electromagnetic wave transmitted by the antenna body and a direction of a main side lobe. A (π / 2 - θ)> A (2 π / 3 - θ) Expression 1 A (π / 2 - θ)> A (π / 3 - θ) Expression 2 SELECTED DRAWING: Figure 1

The invention discloses an ultra-wideband high-angle stability electromagnetic composite structure wave absorber which is formed by periodically arranging a plurality of wave absorber units. Each wave absorber unit comprises a metal bottom plate, a first magnetic material layer, a second magnetic material layer, a first resistive film FSS layer, a first foam supporting layer, a second resistive film FSS layer, a second foam supporting layer and a medium matching layer which are cascaded in sequence, and the first magnetic material layer and the second magnetic material layer are different in size; the patterns of the first resistive film FSS layer and the second resistive film FSS layer are different. The electromagnetic wave absorber has the ultra-wide-band wave absorbing characteristic, the reflection loss can be smaller than 10 dB within the frequency band of 1.6-19 GHz, meanwhile, good angle stability is kept, and the electromagnetic wave absorber has important application prospects in the fields of electromagnetic interference resistance, electromagnetic stealth and the like.

The application provides a wave-absorbing film material with electrostatic adsorption function and a preparation method thereof, and belongs to the field of functional film materials.The wave-absorbing film material with electrostatic adsorption function comprises a PVC film and PP films compounded on both sides of the PVC film; the preparation raw materials of the PVC film comprise an electromagnetic wave absorber, PVC resin particles and an additive; the electromagnetic wave absorber comprises a carbon material type electromagnetic wave absorber; the additive comprises a stabilizer and a plasticizer; the preparation raw materials of the PP film comprise PP resin particles, a filler and an additive; and the additive comprises a toughening agent and a lubricant.The PVC film and the PP film with wave-absorbing function are compounded by a co-extrusion technology, and then the compounded film is subjected to corona treatment to obtain the wave-absorbing film material with electrostatic adsorption function, which has good insulation, excellent electrostatic adsorption capacity, high surface energy and excellent wave-absorbing performance, and can meet the requirements of different use environments.

The invention provides an electromagnetic wave absorbent for a high-frequency band and a preparation method thereof. The preparation method comprises the following steps: (1) adding spherical carbonyl iron powder, a grinding aid and a dispersion medium into a stirring ball-milling tank, and carrying out ball-milling treatment to obtain slurry containing flaky carbonyl iron powder; (2) carrying out filter pressing treatment on the slurry, and separating filtrate and a filter cake to obtain wet powder of which most of the liquid medium is removed; and (3) drying the wet powder under a vacuum condition, removing the residual liquid medium to obtain dried flaky carbonyl iron powder, and screening to obtain the high-frequency band electromagnetic wave absorbent. Common carbonyl iron powder is difficult to meet the requirement of wave absorbing performance at high frequency, and after the common carbonyl iron powder is treated through the preparation method, the electromagnetic wave absorbing capacity of the common carbonyl iron powder at the high-frequency wave band is remarkably improved.

The invention relates to the technical field of electromagnetic wave absorption devices, in particular to a multifunctional metamaterial perfect absorber and a manufacturing method thereof. The invention provides a multifunctional metamaterial perfect absorber and a manufacturing method thereof. The absorber comprises a silicon substrate layer, an adhesion chromium layer, a silicon dioxide thin film spacing layer, a gold thin film spacing layer, a broadband absorption metasurface and a narrowband absorption metasurface. The zirconium nitride concentric ring array is arranged on the broadband absorption metasurface, and the average absorption rate in the visible to near-infrared region wave band is as high as 97.48%; the narrow-band absorption metasurface is provided with a 4 * 4 grid array formed by zirconium nitride, and has 99.99% ultrahigh narrow-band absorption and high refractive index sensitivity. The material has excellent refractive index sensing performance and high thermal chemical stability of the zirconium nitride material, is suitable for the fields of solar energy collection, biosensing, environmental protection and the like, and remarkably improves the energy collection efficiency and the sensing sensitivity.

To provide a technique advantageous for reuse of an electromagnetic wave absorber.SOLUTION: In an electromagnetic wave absorber in which an electromagnetic wave absorbing layer and an adhesive layer are stacked, the adhesive layer includes a first adhesive layer and a second adhesive layer disposed between the first adhesive layer and the electromagnetic wave absorbing layer and in contact with the first adhesive layer and the electromagnetic wave absorbing layer, and the first adhesive layer has a lower adhesive strength than the second adhesive layer.SELECTED DRAWING: Figure 1

The present invention comprises: a lamp housing; a lamp cover that covers an opening portion of the lamp housing; a light source that is disposed in a lamp chamber formed by the lamp housing and the lamp cover; a light reflector; and a radar unit that transmits and receives radar waves. At least a part of the light reflector is an electromagnetic wave absorption part in which an island-shaped metal layer having metallic luster is formed on the surface of an electromagnetic wave absorber.

The invention discloses a lotus petiole type magnetic control tunable electromagnetic wave absorber and a preparation method and application thereof, and belongs to the technical field of wave absorbing materials, and the preparation method comprises the following steps: (1) uniformly mixing conductive particles, magnetic particles, an antioxidant and a plasticizer to obtain mixed particles; (2) uniformly mixing a polymer matrix with a catalyst to obtain a mixture; and (3) uniformly stirring and dispersing the mixed particles and the mixture, injecting into a lotus petiole mold, applying an excitation magnetic field, curing at a constant temperature, and demolding after curing is finished, so as to obtain the lotus petiole type magnetic control tunable electromagnetic wave absorber. The process provided by the invention is simple, electromagnetic parameters and structural response of the material can be flexibly adjusted, so that the wave absorbing frequency band and absorptivity are regulated and controlled, the lotus petiole type magnetic control tunable electromagnetic wave absorber has the tunable electromagnetic wave absorbing characteristic, and the obtained lotus petiole type magnetic control tunable electromagnetic wave absorber can be applied to the field of new-generation intelligent communication and intelligent stealth.

To provide an electromagnetic wave absorber for absorbing millimeter-wave electromagnetic waves which can achieve a large amount of electromagnetic wave absorption, and of which sheet thickness can be easily controlled when used for an electromagnetic wave absorbing sheet.SOLUTION: An electromagnetic absorber includes: a large first electromagnetic wave absorbing substance 10 made of a hollow material with a relatively high dielectric constant; a plurality of small second electromagnetic wave absorbing substances 20 made of granular materials with a relatively low dielectric constant bonded to the surface of the first electromagnetic wave absorbing substance 10; and a binding material 30 that bonds the first electromagnetic wave absorbing material 10 and the second electromagnetic wave absorbing substances 20 together.SELECTED DRAWING: Figure 1

An electromagnetic wave absorber 500 comprises a frequency selective filter layer 400, a dielectric layer 200 positioned below the frequency selective filter layer 400, and a reflective layer 100 positioned below the dielectric layer 200. The reflective layer 100 includes a sheet-shaped first insulator 2 that has a first surface 3, and a first wiring pattern 11 that is provided on the upper surface of the first insulator 2 and is formed from fine metal wires 13. The first wiring pattern 11 has a first point 21, a first line 30 extending from the first point 21, and a second line 33 extending from the first point 21. The angle formed by the first line 30 and the second line 33 is greater than 0 degrees and less than 90 degrees, or is greater than 90 degrees and less than 180 degrees.

The invention discloses a preparation method and application of AgBiX2 nanocrystals, and belongs to the technical field of nanomaterial preparation. According to the preparation method, a thiol organic reagent is adopted to replace a traditional virulent or expensive precursor in a green mode, low-toxicity, low-temperature and efficient dissolution of an X source is achieved, and the AgBiX2 (X: S, Se) nanocrystal which is controllable in shape, good in dispersity and stable in air is successfully prepared through a thermal injection reaction; according to the method, the reaction process is simple, and the defects of the existing method in safety, cost and process are overcome; more importantly, the AgBiX2 is applied as the electromagnetic wave absorbent for the first time, and experiments show that after being compounded with a carbon material, the AgBiX2 shows extremely strong absorption characteristics, wide effective absorption bandwidth and thin matching thickness in the frequency band of 2-18 GHz, and has huge application potential in the aspects of electromagnetic shielding and stealth coatings.

An electromagnetic wave absorber evaluation apparatus including: a housing in which the electromagnetic wave absorber is allowed to be arranged, the housing being made of a conductive material with inner dimensions of a width a, a height b, and a length L, as b<a<L; a substrate arranged inside the housing; an input microstrip line and an output microstrip line formed on the substrate along a length direction of the housing and separated from each other in the length direction; and a signal inspecting unit capable of inputting an input signal having a frequency of 20 GHz or more into the input microstrip line and detecting an output signal output through the output microstrip line, in which an evaluation frequency ft obtained by the Formula (1) satisfies the Formula (2) in a frequency region of 20 GHz or more.

A thermoplastic resin composition for an electromagnetic wave absorber includes a thermoplastic resin (A), a carbon nanotube (B) with an average diameter of 1 to 15 nm, and a carbon black (C) with an average primary particle size of 20 to 50 nm, and satisfies any of (i) to (iv). ΔRL expressed by Equation (1) is 3 dB or less, and ΔTL expressed by Equation (2) is 5 dB or less.

The invention relates to a composite material with Co9S8 / MoS2 bimetallic sulfide heterojunction and a preparation method and application thereof.The preparation method of the composite material comprises the following steps that S1, a cobalt source, dimethylimidazole and hexadecyl trimethyl ammonium bromide are weighed and added into deionized water, stirring and dissolving are conducted, a mixed solution is obtained, then standing, washing and drying are conducted, and ZIF-67 precursor powder is obtained; s2, adding the ZIF-67 precursor powder obtained in S1, a molybdenum source and a sulfur source into deionized water, uniformly stirring, transferring into a reaction kettle for heating reaction, cooling to room temperature, collecting a reaction product, washing, and drying overnight; and S3, placing the sample dried in the step S2 in a reducing atmosphere, and carrying out calcination treatment to obtain the Co9S8 / MoS2 composite material, namely a target product. Compared with the prior art, the composite material provided by the invention has the advantages that the reflection loss intensity of-55.06 dB is realized under the ultrathin thickness of 1.50 mm, and the effective absorption bandwidth reaches 5.28 GHz. The work provides a new view angle for the development of low-density and high-efficiency electromagnetic wave absorbers.

To provide an electromagnetic wave absorber that can improve electromagnetic wave absorption performance. [Solution] The electromagnetic wave absorber according to the present invention contains glass fibers and carbon nanotubes, and the glass fiber content is 80% by mass or more.