1143 results about "Electromagnetic wave absorption" patented technology

By using a high electromagnetic wave absorbing loss material and adding it in a small amount to a matrix, an electromagnetic wave absorber useful for GHz band, which can demonstrate the electromagnetic wave absorption capability without ruining characteristics of the matrix, and can enjoy a good formability and a low manufacturing cost, is provided.The disclosed is an electromagnetic wave absorber which is characterized in that carbon fibrous structures are contained in the matrix, at a rate of 0.01-25% by weight based on the total weight, wherein the carbon fibrous structure comprises a three dimensional network of carbon fibers each having an outside diameter of 15-100 nm, wherein the carbon fibrous structure further comprises a granular part with which the carbon fibers are tied together in the state that the concerned carbon fibers are externally elongated therefrom, and wherein the granular part is produced in a growth process of the carbon fibers.

The invention discloses a bimetallic-organic-framework-based derived porous carbon / multi-wall carbon nanotube nano composite absorbing material and a preparation method thereof. On the basis of a hightemperature pyrolysis method, the porous carbon / multi-wall carbon nanotube nano composite material is prepared by using a multi-wall carbon nano tube as a carrier, cobaltous nitrate hexahydrate and zinc nitrate hexahydrate as metal salt precursors, 2-methylimidazole as an organic ligand, and methanol and ethanol as mixed solvents. The preparation method has good green and environment-friendly effects; no hazardous by products are generated; and the preparation process is simple. The prepared nano composite material has advantages of high electromagnetic wave absorption capacity, large absorption frequency bandwidth and low density. Electromagnetic wave with different wavebands can be absorbed effectively by adjusting the additive amount of the multi-wall carbon nano tube and the coating thickness. The bimetallic-organic-framework-based derived porous carbon / multi-wall carbon nanotube nano composite absorbing material and the preparation method thereof have the great application valuein the electromagnetic absorption and electromagnetic shielding fields.

The invention relates to a graphene oxide and polymer based electromagnetic shielding foam composite material and a preparation method thereof. Flexible polymer foams are selected and are immersed in a graphene oxide aqueous dispersion, then the immersed polymer foams are dried and reduced, and a layer of three-dimensional continuous graphene film structure is formed between a foam skeleton and a skeleton. The graphene film between the skeletons is conducive to improving the electromagnetic wave reflecting surface and beneficial to electromagnetic wave absorption. Through compounding and reduction of the polymer foams and graphene oxide, compounding of flexible polymer foams and graphene with high electromagnetic shielding properties can be realized, the three-dimensional continuous network structure of the polymer foams and graphene guarantees maximization of mechanical and electromagnetic shielding properties, under 80% compressive strain, the obtained foam composite material is compressed repeatedly for 1000 times, the recovery rate is greater than or equal to 95%, and the electromagnetic shielding effectiveness is greater than or equal to 40dB. The method provided by the invention has a simple compounding process, and can realize large-scale production.

The invention relates to water-soluble polymer / graphene composite fiber as well as a preparation method and application thereof. The cross section of the fiber is special-shaped, the surface of the fiber is of an orientated micro-fiber-shaped structure, the strength of the fiber is greater than 100 MPa, the elongation at break is greater than 2%, and the conductivity of the fiber is greater than 0.1 S / cm. The preparation method comprises the following steps: preparing a composite spinning liquid, extruding into a coagulating bath for curing, drafting, leading out of the coagulating bath, drying, and coiling, thereby obtaining the water-soluble polymer / graphene composite fiber; and finally reducing by using a chemical or physical method, thereby obtaining the water-soluble polymer / graphene composite fiber. The cross section of the composite fiber provided by the invention is of a special-shaped structure, the surface of the fiber is of a rich groove micro structure, the strength and the toughness of the fiber are greatly improved when being compared with those of pure graphene fiber, and good conductivity is still maintained, so that the water-soluble polymer / graphene composite fiber has a wide application prospect in the fields such as anti-electrostatic and conductive fabrics, electromagnetic wave absorption and shielding fabrics, energy storage devices, sensors and water treatment.

The invention discloses a method for adjusting the radiation direction of a mobile terminal, and a mobile terminal. The mobile terminal comprises a proximity switch, antennas and a control unit, wherein the proximity switch is used for detecting the distance between a human face and the mobile terminal; the antennas are used for emitting and receiving data and comprise a first-state antenna and a second-state antenna, and the electromagnetic wave absorption ratio SAR value tested by the first-sate antenna is smaller than the SAR value tested by the second-state antenna; and the control unit is used for controlling the antennas to select the first-sate antenna for radiation when the proximity switch detects that the human face is approaching the mobile terminal, and controlling the antennas to select the second-sate antenna for radiation when the proximity switch detects that the human face is away from the mobile terminal. By using the mobile terminal provided by the invention, the unfavorable influence that the mobile terminal exerts on a human body, a hearing aid and the like can be reduced by detecting the distance between the human face and the mobile terminal, and under the condition that the radiation performance of the mobile terminal is ensured, the SAR values and HAC values can be reduced and the user experience and radio frequency performance can be improved.

A heating apparatus using an electromagnetic wave is disclosed, by which cut-of performance of an electromagnetic wave is enhanced by increasing an electromagnetic wave absorption bandwidth having cut-off performance below −70 dB. The present invention includes a door provided to an open front side of a body to be opened / closed and a choke filter having a panel type choke part arranged by at least one row each along an edge of the door and a filter part arranged by at least one row each along an edge of the choke part and having a plurality of slots, wherein a prescribed choke part is provided to a most inner side among rows of the choke and filter part.

Aiming at the problems existing in the present cooling and radiation protection technologies of electronic products, the invention provides an SMD (surface mounted device) with cooling and electromagnetic wave absorption functions, which is applied to electronic equipment. The SMD comprises a decoration layer, a cooling and electromagnetic wave absorption layer for cooling and electromagnetic wave absorption and a mounting layer, wherein the cooling and electromagnetic wave absorption layer is arranged between the decoration layer and the mounting layer. The SMD further comprises a protective stripping layer which is arranged below the mounting layer and used for protecting the adhesiveness of the mounting layer, and the stripping layer is taken off before the SMD is used, and then the SMD is mounted at a position needing cooling and electromagnetic wave absorption. Furthermore, the cooling and electromagnetic wave absorption layer is of a structure consisting of more than two layers, including a cooling layer and an electromagnetic wave absorption layer which are independent from each other; accordingly, the cooling and electromagnetic wave absorption layer can be a single-layer structure and is made of a material with cooling and cooling and electromagnetic wave absorption functions. The invention also provides the preparation and application methods of the SMD. The SMD with cooling and electromagnetic wave absorption functions is applied to a shell of electronic equipment, and the shell of the electronic equipment includes but is not limited to a mobile phone shell, a network card, a panel personal computer shell hot spot, a netbook shell hot spot, notebook computer shell hot spot, game equipment and other consumer mobile equipment can improve cooling effect, reduce temperature and weaken electromagnetic wave radiation.

A conductive pattern basically has a substantially polygonal outline shape which is a polygon and can have a high peak value of the electromagnetic wave absorption amount as compared to a case when the conductive pattern has a circular outline shape. Thus, the conductive pattern is basically a polygon and at least one corner portion is shaped in curve. This reduces or even minimizes the shift of the frequency at which the absorption amount becomes a peak value by the polarization direction of the electromagnetic wave. Accordingly, in at least one embodiment, it is possible to realize an electromagnetic absorber having an excellent electromagnetic wave absorption characteristic exhibiting a high peak value of the absorption amount of the electromagnetic wave and a small shift of frequency at which the absorption amount becomes a peak value by the polarization direction of the electromagnetic wave.

The invention discloses an expandable graphite / polyaniline / cobalt ferrite wave-absorbing material with an anti-electromagnetic interference function and a preparation technology thereof. The invention aims to provide an expandable graphite / polyaniline / cobalt ferrite wave-absorbing material which has strong electromagnetic wave absorbing capability and wide absorption frequency bandwidth and is convenient to use without causing environmental pollution and a preparation technology thereof. According to the invention, the wave-absorbing material consists of paraffin serving as a film forming material and an expandable graphite / polyaniline / cobalt ferrite ternary complex serving as an electromagnetic wave absorbent. The preparation technology of the expandable graphite / polyaniline / cobalt ferrite wave-absorbing material comprises the following steps of: (1) preparing expandable graphite; (2) preparing absolute ethyl alcohol containing expandable graphite; (3) preparing an expandable graphite / polyaniline binary complex; (4) preparing the expandable graphite / polyaniline / cobalt ferrite ternary complex; and (5) weighing the expandable graphite / polyaniline / cobalt ferrite ternary complex and the paraffin, uniformly mixing the expandable graphite / polyaniline / cobalt ferrite ternary complex and the paraffin and performing ball milling to obtain the expandable graphite / polyaniline / cobalt ferrite wave-absorbing material.

The invention relates to a graphene / polyaniline / cobalt composite wave-absorbing material and a preparation method thereof, belonging to the field of preparing an electromagnetic wave absorption material. The wave-absorbing material comprise a film forming material and an electromagnetic wave absorbent, wherein paraffin is adopted as the film forming material, a graphene / polyaniline / cobalt ternary complex is adopted as the electromagnetic wave absorbent, and the mass ratio of the graphene / polyaniline / cobalt ternary complex to the paraffin is 1:1. The preparation method of the material comprises the following steps: (1) preparing graphite oxide; (2) preparing the graphene / polyaniline binary complex; (3) preparing the graphene / polyaniline / cobalt ternary complex; (4) weighing graphene / polyaniline / cobalt ternary complex and paraffin, and evenly mixing to obtain a graphene / polyaniline / cobalt wave-absorbing material. The material has the characteristics of being low in cost, simple in preparation technology, strong in electromagnetic wave absorption capability, wide in absorption frequency band, small in density and the like, achieves good electromagnetic property and stability, and has important application values in the fields of microwave absorption and electromagnetic shielding.

The invention discloses an electromagnetic shielding composite material. Electromagnetic wave absorption layers and electromagnetic wave reflection layers are alternately overlapped to form electromagnetic shielding function bodies; the electromagnetic wave absorption layers are formed by compositing matrix resin, fiber carriers and electromagnetic absorption function bodies; the electromagnetic wave absorption layers are formed by compositing matrix resin and electromagnetic gradient reflection function bodies; in the overlapped electromagnetic wave reflection layers, the mass percentage compositions of short cut carbon fibers increase in gradient along the incident directions of the electromagnetic waves. According to the electromagnetic shielding composite material of the invention, the incident electromagnetic waves generate multi-reflection; the propagation paths of the electromagnetic waves in the material are increased; increase of the multi-reflection loss and absorption loss enables the shielding efficiency of the material to be increased; in adoption of the reflection layers of gradient structure, the electromagnetic waves will not escape away from the shielding material rapidly for reflection; more electromagnetic waves can enter the next shielding unit; therefore, the shielding efficiency of the material is further improved.

The invention relates to aqueous radiation-resistant coating belonging to the chemical engineering technology field. The aqueous radiation-resistant coating takes flaky graphite powder, acetylene carbon power, carbonyl iron powder and ferrite power as main materials with electromagnetic wave absorption function and takes diffusant, cement, film forming agent, ammonia and pure water as auxiliary materials. The aqueous radiation-resistant coating has the electromagnetic wave absorption frequency of 1.0-20000 MHz, can attenuate the electromagnetic wave absorption by 2-20 dB according to the different coating thickness, can solve the unsolvable problem of purifying environment polluted with electromagnetic radiation by shielding material and effectively prevent the harm of electromagnetic radiation to surrounding equipment and personnel.

Disclosed herein are an electromagnetic wave absorbing and shielding film, a method of manufacturing the same, and a cable including the electromagnetic wave absorbing and shielding film. The electromagnetic wave absorbing and shielding film includes an electromagnetic wave absorbing layer, in which a plate-like metal flake is formed using a metal powder in the form of a paste or ink, and an electromagnetic wave shielding layer attached to the electromagnetic wave absorbing layer, thus absorbing and shielding electromagnetic wave and reducing noise.For this, the present invention provides a method of manufacturing an electromagnetic absorbing and shielding film, in which the method includes forming a plate-like metal flake using a spherical metal alloy by an attrition mill, which operates at a predetermined speed for a predetermined time, with the addition of steel use stainless (SUS) balls or ceramic balls and surfactants, and washing the plate-like metal flake with ethyl alcohol, methyl alcohol or water and drying the washed metal flake, the method including: mixing the metal flake powder with resin in a ratio of 30 to 95 wt %:70 to 5 wt % using a mixer and stirring the same to form a metal paste; and coating the metal paste on an electromagnetic wave shielding layer, and a communication cable including the thus formed electromagnetic wave absorbing and shielding film.

A conductive pattern basically has a substantially polygonal outline shape which is a polygon and can have a high peak value of the electromagnetic wave absorption amount as compared to a case when the conductive pattern has a circular outline shape. Thus, the conductive pattern is basically a polygon and at least one corner portion is shaped in curve. This reduces or even minimizes the shift of the frequency at which the absorption amount becomes a peak value by the polarization direction of the electromagnetic wave. Accordingly, in at least one embodiment, it is possible to realize an electromagnetic absorber having an excellent electromagnetic wave absorption characteristic exhibiting a high peak value of the absorption amount of the electromagnetic wave and a small shift of frequency at which the absorption amount becomes a peak value by the polarization direction of the electromagnetic wave.

The invention discloses light thermal insulation mortar with an electromagnetic wave absorption function and a construction method thereof, belonging to the field of building materials. The mortar is composed of a wave absorbent, a gelled material, a filler, a cementing material, lightweight aggregate, a water retention filler and a reinforcing filler. The light thermal insulation mortar of the invention has the advantages of frequency bandwidth absorption (100MHz-18GHz), good wave absorbing effect and heat insulating effect. The light thermal insulation mortar can be applied to constructing civil buildings and military electromagnetic invisible buildings.

The present invention provides a composite film having a linearly-scratched, thin metal film and a plastic film, which has good absorbability to electromagnetic waves in various frequencies, as well as reduced anisotropy in electromagnetic wave absorbability, suitable for electromagnetic wave absorbers, and its production apparatus. The composite film having a linearly-scratched, thin metal film and a plastic film according to the present invention comprises a plastic film, and a single-or multi-layer, thin metal film formed on at least one surface of the plastic film, the thin metal film being provided with large numbers of substantially parallel, intermittent, linear scratches with irregular widths and intervals in plural directions. Its production apparatus comprises pluralities of pattern rolls each having large numbers of fine, high-hardness particles on the surface, which are arranged to form linear scratches on the thin metal film side of a thin metal film-plastic composite film, and means each pressing the pattern roll to the composite film, and pluralities of the pattern rolls being oriented in different directions in a plane in which they are in sliding contact with the thin metal film of the composite film.

The invention provides a graphene and ferric oxide nanometer material and a preparation method for absorbing high-frequency electromagnetic waves. Add 0.08-0.12 grams of graphene to 280-320 milliliters of water to dissolve, then add 0.05-0.15 grams of Fe(NO3)3.9H2O to the solution to obtain a mixed solution, and stir the mixed solution for two hours at 50 degrees Celsius in a water bath, and then The obtained precipitate was separated by centrifugation, washed several times with ethanol and distilled water, and dried in a vacuum environment; the obtained product was heated to 350 degrees Celsius under argon for annealing for 2 hours, and after cooling to room temperature, graphene was obtained with Fe3O4 nanocomposites. The film prepared by using the material of the invention has an absorption intensity below -20dB when the thickness is 3-6mm, and the absorption intensity of microwaves with frequencies around 5.5GHz and 7GHz exceeds -30dB respectively. Moreover, its absorption frequency width is large, less materials are used, and the material of the film material produced is lighter, which is more conducive to industrial production and has wider applications.

The invention discloses a layered MXene loaded cobalt ferrite composite wave-absorbing material. The cobalt ferrite of the composite wave-absorbing material is loaded between layers of layered MXene, and the mass ratio of the cobalt ferrite to the layered MXene is 1: (1-3), wherein the MXene has a unique lamellar microstructure, and the surface of the MXene is rich in functional groups, so that the cobalt ferrite can be loaded between layers or on the surface of the MXene to form a dielectric-magnetic two-phase heterojunction microstructure, and the MXene has a remarkable dielectric polarization loss characteristic; the nano magnetic cobalt ferrite loaded on the MXene has a high-frequency natural resonance effect and a strong magnetic loss mechanism, and the high resistivity of the nano magnetic cobalt ferrite can weaken the strong reflection effect of the MXene on incident electromagnetic waves, so that the composite material is more beneficial to impedance matching with space; therefore, the composite material shows a broadband strong electromagnetic wave absorption characteristic, and a reflectivity result shows that the bandwidth of the composite material is superior to -10dB (90% absorption rate) and reaches 7.2 GHz, and a corresponding absorption peak reaches -21.75 dB.

The invention provides a preparation method of a magnetic nanoparticle loaded graphene aerogel composite material and belongs to the technical field of functional magnetic materials. The method takesgraphene oxide, polyvinyl alcohol and metal salt as raw materials and comprises the following steps: preparing metal salt loaded three-dimensional porous crosslinking network graphene oxide aerogel through a hydrothermal method; freezing and drying, and roasting and reducing under a protection atmosphere to obtain the magnetic nanoparticle loaded graphene aerogel composite material in situ. The preparation method provided by the invention has the advantages of simplicity in operation, low cost and simple preparation technology and is a novel technology for macro preparation of the nanoparticlegraphene aerogel composite material; the magnetic performance and electric performance of the composite material can be adjusted through adjusting the ratio of graphene to the metal salt, and the prepared graphene aerogel composite material has the advantages of high specific surface area, small density, excellent electromagnetic performance and the like and can be used for an electromagnetic wave absorption material.

A graphene / magnetic particle / polyaniline composite porous wave-absorbing material and a preparing method thereof are disclosed. The composite porous wave-absorbing material comprises, by mass, 5-30 wt% of graphene, 5-20 wt% of magnetic particles, 45-90 wt% of polyaniline and 1-5 wt% of a foaming agent. The composite porous wave-absorbing material is prepared by loading the graphene sheet surfaces with the magnetic particles by a solvothermal method, cladding the graphene sheet surfaces loaded with the magnetic particles with the polyaniline through an in-situ polymerization process, performing heating and foaming by using the foaming agent, and performing high-temperature carbonization. The material has characteristics of a low cost, a simple preparing process, high electromagnetic wave absorption capability, a wide absorption bandwidth, and the like, and has a wide application prospect in sensing techniques, electromagnetic shielding, radar absorption, and other wave-absorbing fields.

The invention discloses a graphene aerogel and a preparation method and an application thereof, wherein the aerogel is prepared from the following method: (1) pre-reduction treatment: adding a reducing agent to a graphene oxide solution, mixing, carrying out ultrasonic dispersion, and carrying out pre-reduction treatment, to obtain a semi-reduction graphene hydrogel; (2) final reduction treatment:adding a reducing agent, carrying out ultrasonic treatment, and then carrying out final reduction treatment, to obtain a graphene hydrogel; and (3) acid / alkali soaking: placing the graphene hydrogelin an acid or alkali aqueous solution, soaking, washing the hydrogel to be neutral, sucking out the excess liquid, and carrying out freeze drying, to obtain the graphene aerogel. The graphene aerogelis applied to electromagnetic wave absorption materials. The graphene aerogel obtained by the method has small density and good integrality, and has a certain mechanical strength and resillency; the prepared wave absorbing material has good electromagnetic wave absorption performance, and the wave absorbing performance can be adjusted; and the method has the advantages of simple process, short production cycle, low cost and good benefits, and is suitable for industrialized production.

Disclosed is an adhesive tape including a first adhesive layer and a second adhesive layer. More particularly, the first adhesive layer has a porous structure and contains a heat conductive filler, and the second adhesive layer has a non-porous structure and contains at least one filler selected from the group consisting of a heat conductive filler, an electromagnetic wave shielding filler and an electromagnetic wave absorbing filler. The adhesive tape may be applied to electronic products, especially to electronic products requiring a large area of adhesion, such as a plasma display panel (PDP).

The invention relates to pumice wave absorbing aggregate with an electromagnetic wave absorbing function and a preparation method of the pumice wave absorbing aggregate, belonging to the technical field of building wave absorbing materials. The pumice wave absorbing aggregate is characterized in that the surface of natural pumice is covered by a wave absorbing layer, the wave absorbing layer comprises dry materials and water and the dry materials comprise cement and wave absorbing agent; and the ratio of cement to wave absorbing agent is (80 to 95):(20 to 5). The pumice wave absorbing aggregate with the electromagnetic wave absorbing function and the preparation method of the pumice wave absorbing aggregate have the advantages that the problems that the water absorbing capacity of the natural pumice aggregate is high, the strength is not high, the wave absorbing agent is not evenly dispersed in concrete and the like are solved, the source of raw materials is wide, the process is simple, and the pumice wave absorbing aggregate can be used for constructing cast-in-situ wall bodies and roofs, can also be used for making concrete products such as wall boards, building blocks, roof boards and the like, has good heat insulating and wave absorbing performance and is suitable for industrialized production.

The present invention discloses a fused sheet for electromagnetic wave absorption / extinction and shielding, and for electronic equipment high heat dissipation. The fused sheet for electromagnetic wave absorption / extinction and shielding, and for electronic equipment high heat dissipation of the present invention includes a premolded graphite sheet prepared by molding a graphite substrate into a sheet form having a density in a range of 0.1-1.5 g / cm3 and an incomplete state of crystal structure; and a porous metal sheet having a plurality of pores connected to upper and lower surfaces of the porous metal sheet, wherein the premolded graphite sheet is stacked on one surface of the porous metal sheet, and press molded to be integrally attached and combined, so as to have a density of 1.6 g / cm3-6.0 g / cm3

An object of the present invention is to provide a method for producing an electromagnetic wave absorbing sheet with properties thereof further improved. A treated powder P0 pulverized and flaked in a pulverizing step is placed in a centrifugal gas-flow classifier 50. The treated powder is classified into a flaky soft magnetic metal powder P1 and a non-flaky powder P2 on the basis of the difference between the centrifugal force and the drag acting on each of these powders in a gas flow circling in a chamber 51. The non-flaky powder P2 is eliminated and the flaky soft magnetic metal powder P1 is used to form an electromagnetic wave absorbing sheet, the performances of the electromagnetic wave absorbing sheet being thereby improved. The classified non-flaky powder P2 is preferably recycled as the raw material powder used in the pulverizing step.

The invention discloses a Co / C composite nanofiber microwave absorbent. The microwave absorbent comprises magnetic Co nanoparticles and carbon nanofiber, wherein the Co nanoparticles are uniformly distributed in the carbon nanofiber or on the surface of the carbon nanofiber, and are wrapped by a graphitized carbon layer. The invention also discloses a preparation method for the Co / C composite nanofiber microwave absorbent. The method combines electrostatic spinning with later-stage heat treatment to prepare the Co / C composite nanofiber microwave absorbent by a one-step method, the synthesis process is simple and the average diameter of the obtained fiber is 200 to 500 nm. The Co / C composite nanofiber microwave absorbent prepared by the method has strong antioxidant and corrosion-resistant abilities, is an electromagnetic wave absorbing material with excellent comprehensive performance, has the advantages of light weight, wideband, strong absorption capacity and convenient and adjustable electromagnetic parameters, and has an excellent application prospect in the technical fields of electromagnetic stealth, electromagnetic shielding, resistance to electromagnetism radiation interference and the like.