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134 results about "Microwave absorber" patented technology

Method for quickly preparing quasi-graphite-structure carbon nitride material by adopting microwave heating

The invention relates to a quick, energy-saving and high-yield preparation method of quasi-graphite-structure carbon nitride catalysis materials and application of the materials, belonging to the field of preparation and application of catalysis materials. According to the preparation process, one or multiple nitrogen-rich small organic molecules of urea, melamine, thiourea, cyanamide, dicyanamide, cyanuric chloride and cyanuric acid is / are taken as raw materials, a simple metal substance, a metallic oxide, a metal sulfide and a metal chloride are taken as microwave absorbers, microwave is taken as a heating source, and under the condition of radiation of microwave, the quasi-graphite-structure carbon nitride material can be quickly prepared. The prepared carbon nitride material has a large specific area and crystallinity and has high photocatalytic water decomposition hydrogen production performance and organic pollutant degradation performance. The preparation method provided by the invention is short in time, small in energy consumption, high in production efficiency and simple in process, does not have harsh preparation conditions, is easy to operate and has wide application prospect.
Owner:ANHUI UNIVERSITY

Radar level gauging system

InactiveUS20070236385A1Leveling precisionAccurate level measurementWaveguide mouthsLevel indicatorsRadarAbsorbed energy
A radar level gauging system comprising a microwave unit for transmitting and receiving first microwaves having a first and second distinguishable characteristics, a microwave absorber adapted to be arranged in a bottom region of the tank and adapted to absorb electromagnetic energy of microwaves having one of the first and second characteristics, and processing circuitry adapted to determine the product level based on a relationship between transmitted and received microwaves. The system thus emits microwaves in two channels, and the absorber is arranged to absorb energy in only one of the channels. Using the absorbed channel, it is possible to obtain a measurement with very limited interference from the bottom, which thus will be accurate also for levels close to the bottom. Using the unabsorbed channel, it is possible to obtain a reference measurement of the distance to the reflecting part of the absorber, thus enabling verification of the of the system.
Owner:ROSEMOUNT TANK RADAR

Radar level gauging system

A radar level gauging system comprising a microwave unit for transmitting and receiving first microwaves having a first and second distinguishable characteristics, a microwave absorber adapted to be arranged in a bottom region of the tank and adapted to absorb electromagnetic energy of microwaves having one of the first and second characteristics, and processing circuitry adapted to determine the product level based on a relationship between transmitted and received microwaves.The system thus emits microwaves in two channels, and the absorber is arranged to absorb energy in only one of the channels. Using the absorbed channel, it is possible to obtain a measurement with very limited interference from the bottom, which thus will be accurate also for levels close to the bottom. Using the unabsorbed channel, it is possible to obtain a reference measurement of the distance to the reflecting part of the absorber, thus enabling verification of the of the system.
Owner:ROSEMOUNT TANK RADAR

Method for preparing carbon-coated LiFePO4 by microwaves and carbon-coated LiFePO4 material

The invention provides a method for preparing carbon-coated LiFePO4 by microwaves, which comprises the following steps: respectively obtaining a lithium source compound, a ferrous iron source compound and a phosphorous source compound in a stoichiometric ratio of the LiFePO4 required to be prepared, and adding a microwave absorber, an organic carbon source and a liquid dispersant; performing ball milling on the obtained raw material and drying treatment; putting the dried product in a microwave heating reaction cavity, and introducing protective gas into the reaction cavity; and heating to the temperature of between 550 and 850DEG C with the microwaves, introducing carbon source gas, and performing pyrolysis on the carbon source gas at the temperature of between 550 and 850DEG C to prepare the carbon-coated LiFePO4. The invention also provides a carbon-coated LiFePO4 material prepared by the method. The preparation method adopts microwave heating, and the carbon source gas is subjected to pyrolysis, so that the carbon species are deposited on the surface of the LiFePO4 to obtain the complete, uniform and firm carbon-coated LiFePO4; and simultaneously, by the preparation method, the machining property and the electrochemical performance of the LiFePO4 material can be obviously improved.
Owner:SHENZHEN UNIV

Single and multi-band microwave absorbers

The invention discloses a single frequency band microwave absorber and a multiple frequency band microwave absorber, wherein the multiple frequency band microwave absorber comprises a plurality of annular artificial electromagnetic materials (1), a metallic back board (3) and a medium substrate (2) arranged between the metallic back board (3) and the annular artificial electromagnetic materials (1); the annular artificial electromagnetic materials (1) are mutually embedded and sleeved and are concentrically arranged; and the single frequency band microwave absorber comprises an annular artificial electromagnetic material (1), a metallic back board (3) and a thickness-adjustable medium substrate (2) arranged between the metallic back board (3) and the annular artificial electromagnetic material (1). The multiple frequency band microwave absorber disclosed by the invention has a perfect absorbing effect for large-angle oblique-incidence microwaves. In practical application, the electromagnetic environment is complicated and oblique-incidence waves are commoner than normal-incidence waves, thus the single frequency band microwave absorber and the multiple frequency band microwave absorber can excellently suit the complicated electromagnetic environment. The annular artificial electromagnetic materials (1) adopted by the single frequency band microwave absorber and the multiple frequency band microwave absorber are single-layer, so that the single frequency band microwave absorber and the multiple frequency band microwave absorber have thin thickness and light weight and are easy to conform.
Owner:SOUTHEAST UNIV

Method for preparing ferrite nano fiber

The invention discloses a method for preparing a ferrite nano fiber. The method comprises the following steps of: dissolving metal salt which can form ferrite into glacial acetic acid, adding deionized water to obtain metal salt solution; weighing Fe(3+) salt and dissolving the Fe(3+) salt into the deionized water; evenly stirring to obtain Fe(3+) salt solution; weighing citric acid according to a certain ratio, dissolving the citric acid in the Fe(3+) salt solution, mixing the obtained solution with metal salt solution, and then evaporating the obtained solution to form collosol; weighing an organic complexing agent, and dissolving the organic complexing agent into absolute ethyl alcohol or deionized water, so as to obtain organic complexing agent solution; adding the obtained gel to the obtained organic complexing agent solution and evenly agitating, so as to obtain spinnable precursor solution; carrying out electrostatic spinning to prepare a precursor fiber; and then drying, and burning for 1-3 hours in air atmosphere at 700-1000 DEG C, so as to obtain the ferrite nano fiber. The ferrite nano fiber with high performance disclosed by the invention can be used as a magnetic recording material, an electromagnetic microwave absorber and a structural wave-absorbing material.
Owner:JIANGSU UNIV

Process of preparing graphene by low-frequency electromagnetic wave

The present invention relates to a process of inducing grapheme by low-frequency electromagnetic wave, which includes the following steps: (A) providing a substrate; (B) optionally forming a metal layer on the substrate; (C) providing a carbon source to form a carbon-containing layer locating on the metal layer; and (D) performing a treatment of the carbon-containing layer formed on the metal layer by using low-frequency electromagnetic wave, wherein the low-frequency electromagnetic wave is provided by microwave device. The electromagnetic energy from the microwave field device is converted to thermal energy by microwave absorber (for example, SiC) as a media to directly heat the carbon-containing layer, so that carbon atoms get kinetic energy to form grapheme layers on the surface of the metal layer and between the metal layer and the substrate.
Owner:NATIONAL TSING HUA UNIVERSITY

Ultra wideband material microwave absorber loaded with chip resistor

InactiveCN105514619AAchieving Loss AbsorptionAchieve the effect of ultra-wideband impedance matchingMagnetic/electric field screeningAntennasUltra-widebandEngineering
The invention provides an ultra wideband material microwave absorber loaded with a chip resistor. The ultra wideband material microwave absorber comprises a unit structure and a bottom plate, wherein the unit structure is positioned on the bottom plate; the unit structure comprises a medium substrate, a metal slotting ring structure, the chip resistor and a metal back plate; the metal slotting ring structure is respectively connected with the medium substrate and the chip resistor. The ultra wideband material microwave absorber has the advantages that the strong circuit resonance and impedance matching properties are produced by the slotting ring structure loaded with the chip resistor, so that the ultra wideband impedance matching effect is realized, and the ultra wideband microwave strong absorbing effect is realized; when the electromagnetic wave is irradiated to the absorber, a magnetic field loop is generated around the resonance structure, a metal sheet and the chip resistor can produce ohm loss by the magnetic field loop, the electromagnetic energy of the electromagnetic wave is converted into heat energy by loss, then the loss of the irradiated electromagnetic wave is absorbed, and the ultra wideband high-property absorbing is realized; the structure is simple and small, the cost is low, the preparation is convenient, and the like.
Owner:WUHAN UNIV OF SCI & TECH

Frequency-adjustable microwave absorber

The invention provides a frequency-adjustable microwave absorber, which is formed by a plurality of wave absorbing units on the sub wave length dimension through regular arrangement in the orthogonal direction. The frequency-adjustable microwave absorber is characterized in that capacitance and inductance coupling units are processed on the upper surface of a medium base plate, variable capacitance diodes are used for welding the adjacent capacitance and inductance coupling units, the positive and negative electrodes of each variable capacitance diode are respectively connected with a direct current feed line arranged at the back side of the medium base plate through one metallization through hole, all feed lines are combined into a feed network, the feed network at the lower surface of the medium base plate is divided into two parts including a positive part and a negative part, the two parts are respectively connected with the negative electrodes and the positive electrodes of all of the variable capacitance diodes, and the reverse bias is exerted on all of the variable capacitance diodes arranged on the upper surface of the medium base plate, and the current voltage source voltage is regulated in a range not exceeding the breakthrough voltage value of the variable capacitance diodes for changing the equivalent parameters of the variable capacitance diodes. The frequency-adjustable microwave absorber has the adjustable characteristics, the absorption frequency points in the wider bandwidth range are continuously adjustable, in addition, the regulation is very convenient, and wide application prospects can be realized in the fields of invisibility, radiation meters and the like.
Owner:SOUTHEAST UNIV

Hexagonal sheet-like barium ferrite magnetic nanometer powder preparation method

A preparing method of hexagonal piece barium ferrite nanometer magnetic powder includes: the predecessor body composed with the mixture of powdered BaCO3 and FeO(OH) powder the fineness of which belongs to nanometer is burnt for hexagonal piece barium ferrite nanometer magnetic powder. The optimal fineness of powered BaCO3 is nanometer and optimal nanometer FeO(OH) powder is the spindly FeO(OH) powder. The invention is suitable for application of perpendicular magnetic recording medium of high density and microwave absorber. The invention has the outstanding advantages as follows: well energy conservation effect for low calcinations heat and short calcinations time; high purity and good crystal model; simple process, low level demand for production facility, that is suitable for mass production in industry.
Owner:INST OF METAL RESEARCH - CHINESE ACAD OF SCI

Transparent ultra-wideband microwave absorber based on transparent conductive film

The invention discloses a transparent ultra-wideband microwave absorber based on a transparent conductive film. The transparent ultra-wideband microwave absorber comprises a transparent substrate andthe transparent conductive film which is coated on the two surfaces of the transparent substrate. Periodically distributed wave absorbing structures are etched on the corresponding film of the microwave incident surface. Impedance matching of the impedance of the wave absorbing structures and the impedance of electromagnetic waves in the free space can be realized under the electromagnetic waves of the unabsorbed frequency. The absorbing bandwidth of the wave absorber can be 23.4 GHz, the overall thickness is 1.1mm, the bandwidth is only 0.11 time of the corresponding wavelength of 32.5GHz center frequency and the microwave absorber is insensitive to the polarization angle.
Owner:NANJING UNIV OF SCI & TECH

Porous alumina ceramic, and preparation method and application thereof

InactiveCN104671826AAperture regulationParts by volume regulationCeramicwareThermal insulationDual mode
The invention provides a porous alumina ceramic with three-dimensional intercommunicating-pore-structure and dual-mode pore size distribution. The preparation method comprises the following steps: by using amorphous alumina, transitional-phase alumina or corundum-phase alumina powder with the particle size of 10-200nm as the raw material powder, adding pore forming agent powder with the particle size of greater than 500nm, uniformly mixing, forming, sintering, processing into the required shape, and removing the pore forming agent. The porous alumina ceramic material has the dual-mode-distribution three-dimensional interlocking-pore structure, has favorable compression strength, thus, can be used as a filter separation material, an adsorbent carrier, a catalyst support, a microwave absorber carrier, artificial bone, a thermal-insulation material and the like, and has favorable application prospects.
Owner:NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI

Broadband microwave absorber based on folded dipole

The invention relates to a microwave absorber with broadband absorption characteristics, in particular to a broadband microwave absorber based on a folded dipole. According to the broadband microwave absorber, a folded dipole antenna serves as a design starting point, an antenna array with a broadband is designed based on a smith chart impedance adjustment method, furthermore, a feed source is replaced by a load resistor based on the reciprocity principle of the antenna, and therefore the microwave absorber with the broadband absorption characteristics is obtained. A dielectric layer of the absorber is of a double-layer structure, the upper layer is a common dielectric substrate, and the lower layer is common polystyrene foam materials (the dielectric constant is approximately 1.07). Although double-layer dielectric materials are adopted, a single-layer metal SMD circuit is adopted to be used in cooperation with a thin film SMD resistor. The broadband microwave absorber based on the folded dipole is simpler in structure, easier to process, low in cost and light in weight, and therefore mass production can be achieved.
Owner:NANJING UNIV OF SCI & TECH

Incorporation of metal nanoparticles into wood substrate and methods

Metal nano articles were incorporated into wood. Ionic liquids were used to expand the wood cell wall structure for nanoparticle incorporation into the cell wall structure. Nanoparticles of elemental gold or silver were found to be effective surface enhanced Raman spectroscopy (SERS) imaging contrast or sensing agents. Nanoparticles of elemental iron were found to be efficient microwave absorbers and caused localized heating for disrupting the integrity of the lignocellulosic matrix. Controls suggest that the localized beating around the iron nanoparticles reduces losses of cellulose in the form of water volatiles and CO2. The ionic liquid is needed during the incorporation process at room temperature. The use of small amounts of ionic liquid combined with the absence of an ionic liquid purification step and a lower energy and water use are expected to reduce costs in an up-scaled pretreatment process.
Owner:TRIAD NAT SECURITY LLC

Adjustable terahertz broadband microwave absorber

The invention discloses an adjustable terahertz broadband microwave absorber. A plurality of periodic units are periodically arranged; the periodic unit has a multilayer structure including a patch layer, a dielectric layer and a vanadium dioxide thin film layer, the dielectric layer is located between the patch layer and the vanadium dioxide thin film layer, wherein a plurality of metal patches disposed on the dielectric layer form a patch layer. The adjustable terahertz broadband microwave absorber of the invention provides a microwave absorber structure based on vanadium dioxide, and can realize the broadband strong absorption of terahertz waves; by adopting the temperature control property of vanadium dioxide, the dynamic adjustment of absorbing property can be realized; the performance of microwave absorber is not sensitive to the position of metal patch, which reduces the requirement of processing and production and has stronger practicability, the structure is simple and can beapplied to absorb electromagnetic wave in other frequency bands such as far-infrared, middle-infrared and so on.
Owner:BEIJING UNIV OF POSTS & TELECOMM

Three-band switchable metamaterial microwave absorber/reflector

ActiveCN109004370AAchieve total reflection effectAntennasDielectric substrateMicrowave range
The invention relates to the field of microwave absorbing materials. A 3-band switchable metamaterial microwave absorb / reflector is composed of metamaterial unit crystal cladding continuously and periodically arranged, and each metamaterial unit crystal cladding comprise a metal base plate layer, a dielectric substrate layer and a metal pattern layer, wherein that metal pattern layer is composed of an open straight cross structure, an open windmill structure and an open square ring structure. Seven absorption effect and one total reflection effect can be realized in a certain microwave range by meticulously design that structure of the resonant unit and the feeding network and controlling the state of the diode at different positions.
Owner:SHANXI UNIV

A metamaterial-based unidirectional non-reciprocal microwave absorber and a generation method thereof

A metamaterial-based unidirectional non-reflective non-reciprocal microwave absorber disclosed in the invention includes at least two pair of metamaterial structures perpendicular to each other, thattwo pairs of metamaterial structures bee asymmetrical in X, Y and Z directions. The invention does not need to introduce a nonlinear material, but constructs artificial second-order nonlinear materialby artificially constructing mutually perpendicular metamaterial units to destroy the spatio-temporal parity characteristic of the equivalent permeability. The unidirectional microwave absorber withthe structure can exhibit obvious non-reciprocity characteristic for waves coming in different directions. The unidirectional non-reflective non-reciprocal absorber can work in two working modes, andit can work independently and without interference, which improves the efficiency and stability of the absorber. It has a wide range of applications in filters, sensors and photonic devices. The invention has the characteristics of popular structure, simple process, flexible design, strong functionality and the like.
Owner:NANJING UNIV OF POSTS & TELECOMM

High power waveguide impedance transformer

The invention relates to a high power waveguide impedance transformer that comprises a main waveguide, a water load, a short-circuit piston part and a terminal short circuit piston block, wherein circular flow water is used as a microwave absorber in the water load. The working waveguide wavelength of the transformer is lambda g. The front end portion of the water load is in a cone shape as well as the rear end of the water load is in a cylindrical shape and is connected with the short-circuit piston part. There is smooth transition between the front end cone and the rear end cylinder. The length L of the cone is greater than or is equal to 1 lambda g and the cone angle of the cone is from 5 degrees to 15 degrees. The length Lb of the cylinder is in a range of from 1 lambda g to 1.5 lambda g. According to the invention, an input standing-wave ratio can be adjusted in a range of from 1.05 to 5.0 and a phase variance can be adjusted in a range of from 0 degree to 180 degrees; the fluctuation range of the standing-wave ratio is basically in a ranged of -5% to +5%; after a corresponded waveguide caliber size is changed, the transformer can work at different frequencies from 2.0 GHz to 12.4 GHz; therefore, the transformer can be conveniently applied to accurate measurement on a performance parameter of a high power microwave signal source and microwave leakage can be avoided.
Owner:GUANGDONG WITOL VACUUM ELECTRONICS MFR

Novel high power water load

The invention relates to a novel high power water load. The novel high power water load comprises a waveguide radiation horn mouth, a base, a spiral water chamber, a terminal short circuit block, and a protection housing disposed on the outer side of the spiral water chamber. Spiral type flowing water used as a microwave absorber is disposed in the spiral water chamber. The front end of the spiral water chamber is in the shape of a cone, and the rear end of the spiral water chamber is in the shape of a cylinder. One end of the waveguide radiation horn mouth is fixedly connected with an output radiation waveguide, and the other end of the waveguide radiation horn mouth is connected with the base. The other end of the base is connected with the rear end of the spiral water chamber and the bottom part of the protection housing, and the side of the base connected with the spiral water chamber is provided with a groove embedded in the rear end bottom part of the spiral water chamber. The side of the rear end of the spiral water chamber connected with the base is a water inlet, and the side of the front end of the spiral water chamber is a water outlet. The front end of the terminal short circuit block is in the shape of a cone, and is embedded in the front end of the spiral water chamber, and the rear end of the terminal short circuit block is connected with the top part of the protection housing. The water load is capable of satisfying use requirements of a high power millimeter wave electric vacuum device, and at the same time, the broadband low reflection of the water load is realized.
Owner:UNIV OF ELECTRONICS SCI & TECH OF CHINA

Production method of terahertz narrow-band microwave absorber capable of dynamically adjusting absorption peak position

The invention discloses a production method of a terahertz narrow-band microwave absorber capable of dynamically adjusting the absorption peak position. The method mainly comprises technologies such as multilayer thin-film deposition on a silicon substrate, photoetching, dry etching, wet etching and the like. The method is characterized in that the produced microwave absorber adopts an array structure, a micro-mirror capable of rotating around a shaft under the effect of the electrostatic force is arranged in the center of each unit in the array structure, and an I-shaped metal resonator is arranged in the center of the surface of each micro-mirror and used for producing resonance absorption. The terahertz narrow-band microwave absorber produced with the production method of the terahertz narrow-band microwave absorber capable of dynamically adjusting the absorption peak position and applicable to a terahertz frequency band can dynamically and continuously adjust the absorption peak position, so that the defect that absorption peak positions of conventional terahertz microwave absorbers are not adjustable is overcome. The terahertz microwave absorber can greatly increase the frequency selectivity and has very important application values in fields of terahertz detection, terahertz filtering and frequency-selective terahertz thermal imaging.
Owner:GUILIN UNIV OF ELECTRONIC TECH

Method for rapidly preparing graphite phase carbon nitride nanorods without template

The invention discloses a method for rapidly preparing graphite phase carbon nitride nanorods without a template. The method is characterized by comprising the following steps of firstly preparing melamine micro-nano rods by a self-assembly method using melamine powder as a precursor; then uniformly mixing the prepared micro-nano rods and a microwave absorber, and placing in a ceramic crucible; finally, placing the crucible in the center of a high-energy microwave oven resonant cavity, vacuuming, conducting high-energy microwave irradiation heating, and rapidly obtaining the graphite phase carbon nitride nanorods. The method can efficiently and rapidly prepare the graphite phase carbon nitride nanorods with a high specific surface area, a high purity and a high yield without the template,and the nanorods have a length to diameter ratio of 10-20, and can be applied to fields of photohydrolysis of water to produce hydrogen and photohydrolysis of organic pollutants, biochemical sensors and the like.
Owner:ZHANGJIAGANG DONGDA IND TECH RES INST

Miniature waveguide mode circulator

The invention provides a miniature waveguide mode circulator which comprises an upper shell, a lower shell, a Y-shaped junction waveguide and ferrite elements, wherein permanent magnets are arranged on the upper shell and the lower shell, a waveguide impedance transformer is arranged on a wide-edge plane of the Y-shaped junction waveguide, and the two ferrite elements are positioned on a center axle line of the waveguide impedance transformer and the permanent magnets; metal electromagnetic conductors are placed into the Y-shaped junction waveguide and connected with the corresponding edge of the Y-shaped junction waveguide, the width of a port of the Y-shaped junction waveguide is less than the half-wavelength of a working frequency, the metal electromagnetic conductors extend from a Y-shaped junction plane of the Y-shaped junction waveguide and are mutually isolated; and at least one microwave absorber element is arranged at two sides of each metal electromagnetic conductor and used for absorbing a reflection power of the port. The miniature waveguide mode circulator is in a structure of matching a waveguide thin stick with a terminal load, is suitable for miniature waveguide isolator elements, has the advantages of small total size, light weight and ideal isolation property, and is used for filtering a high-order mode by adopting a combination mode of a plurality of waveguide isolators.
Owner:SDP TELECOM SUZHOU

Graphene-based dual-band terahertz (THz) microwave absorber

The invention discloses a graphene-based dual-band terahertz (THz) microwave absorber, which belongs to microwave absorbers in the technical field of terahertz and utilizes the surface plasmon characteristics of graphene. The wave absorber is a two-dimensional periodic structure and has the following structural components: a metal strip (1) made of gold, an aluminum dioxide dielectric layer (2), agraphene absorber layer (3), a polymethylmethacrylate (PMMA) dielectric layer (4), a silicon dioxide substrate layer (5), and a bottom metal reflective layer (6). The absorption spectrum of the terahertz wave is simulated and calculated by a finite element method. The structure of the wave absorber is optimized and the ideal absorption effect is obtained. The wave absorber has the advantages of simple structure and easy processing; and because of the special optical property of graphene, the absorption peak position can be adjusted by doping.
Owner:CHINA JILIANG UNIV

Control and synthesis method for graphene-like carbon nitride ultrathin nanosheet

The invention discloses a control and synthesis method for a graphene-like carbon nitride ultrathin nanosheet, which comprises the following preparation steps: weighing nitrogen-enriched organic matters such as melamine, cyanuric acid and dicyandiamide according to proportion to be used as material precursors, and weighing boric acid or boron oxide used as shape control agents according to proportion, heating to 70-80 DEG C in a water solution for dissolving and mixing, and after being dissolved to present uniformly milk white, separating out and compounding; then drying, thus obtaining the uniformly compounded midbody; uniformly mixing the midbody with a carbon fiber microwave absorber, and then putting into a crucible; putting the crucible to the central position in a microwave cavity, vacuumizing until the pressure in the microwave cavity is 5-35kPa, setting microwave power to be 2-10kW, quickly heating the material to 500-620 DEG C by microwave irradiation, and carrying out thermalreaction for 5-30min, thus obtaining the ultrathin carbon nitride nanosheet with a graphene-like structure. By adopting the method disclosed by the invention, the ultrathin carbon nitride nanosheet with the graphene-like structure can be simply, conveniently and rapidly synthesized with advantages.
Owner:ZHANGJIAGANG DONGDA IND TECH RES INST +1

Microwave induced crosslinking polyolefin insulation material and preparation method thereof

InactiveCN103435896ALittle influence on mechanical and physical propertiesImprove mechanical propertiesHeat deflection temperaturePolymer science
The invention relates to a microwave induced crosslinking polyolefin insulation material and a preparation method thereof. The invention aims to solve the problems of low strength, low heat-deformation temperature and low solvent resistance in the common polyolefin material, and the problems of complex technique, harsh protecting requirements, low production efficiency, high product cost and poor stability in the existing crosslinking method. The microwave induced crosslinking polyolefin insulation material provided by the invention is prepared from dry polyolefin resin, silane coupling agent, microwave absorber, water bringing agent, polyfunctional group crosslinking agent, crosslinking accelerator and antioxidant. The preparation method comprises the following steps: 1. weighing the components; 2 banburying the components in a Banbury mixer, melting and mixing, and granulating in a single screw extruder to obtain sample granules; and 3. tabletting the obtained sample granules in a vulcanizer, and carrying out microwave induced crosslinking reaction in microwave equipment to obtain the microwave induced crosslinking polyolefin insulation material. The invention is applicable to the fields of wire cable insulation, polyolefin boards and tube products.
Owner:HONGLONGJIANG ORIENT SCI & TECH

Microwave absorber, especially for high temperature applications

A microwave absorber, especially for high temperature applications, has at least one resistive sheet and at least one dielectric layer. The resistive sheet has a material of construction that is a MAX phase material.
Owner:TOTALFORSVARETAB FORSKNINGSINSTITUT FOI

A THz ultra-wideband microwave absorber based on unequally spaced stack structure

InactiveCN109066096AAchieve absorptionInsensitive to incident electromagnetic wave polarizationAntennasUltra-widebandStructural unit
The invention discloses a THz ultra-wideband microwave absorber based on an unequal-spacing laminated structure, comprising a reflecting plate and a dielectric body above the reflecting plate, whereinthe dielectric body is tapered, and at least one layer of metal resonant units periodically arranged by structural units is arranged inside the dielectric body; The metal resonant unit is centrosymmetrical and consists of three metal patches, comprising a hexagonal ring structure of the outer layer, a ring structure of the middle layer and an X-shaped broken line structure of the inner layer. Theinvention is designed based on the principle that the absorption frequency band can be broadened by the multilayer structure, which breaks through the traditional design idea that the layer spacing is equal, and adopts a laminated structure with unequal spacing to widen the absorption frequency domain to realize the ultra-wideband absorption of the THz band.
Owner:NANJING UNIV OF POSTS & TELECOMM

Method for preparing graphene by taking coal as raw material

InactiveCN107892293ALow costEnhanced displacement polarizationGrapheneBulk chemical productionSocial benefitsMicrowave pyrolysis
The invention discloses a method for preparing graphene by taking coal as a raw material, and in particular relates to a method for preparing graphene by utilizing a microwave pyrolysis technology anda supercritical carbon dioxide technology. The method comprises the following steps: by taking low-rank coal as a raw material, matching with a certain proportion of a microwave absorber and a catalyst, drying after uniformly mixing, placing the mixture in a microwave pyrolysis reactor, carrying out two stages of reaction at a final temperature of 400-650 DEG C and a final temperature of 800-1000DEG C, then cleaning, mixing cleaned samples with a dispersant and then placing the mixture in a supercritical carbon dioxide medium for reaction, and cleaning after the completion of the reaction toobtain thin-layer graphene. According to the method, the production cost of graphene can be significantly reduced, the process is simple, in the product quality is high, sources of raw materials arewide, and the method has good economical and social benefits.
Owner:韩笑峰

Salisbury screen flexible Terahertz microwave absorber based on DAST and preparation method thereof

The invention discloses a Salisbury screen flexible Terahertz microwave absorber based on DAST and a preparation method thereof. The absorber comprises a surface-layer DAST organic material layer, anintermediate thin film layer and a base layer metal thin film layer. The surface-layer DAST organic material layer is one kind of a DAST organic single crystal or a DAST organic thin film. The DAST organic single crystal or the DAST organic thin film absorbs waves in the Terahertz waveband. The three layers meet the impedance matching condition of the Salisbury screen flexible Terahertz microwaveabsorber. By use of the Terahertz wave absorption of the DAST organic material layer, the absorber has quite high alternating current conductivity. By designing the whole structure size, impedance matching of the Salisbury screen flexible Terahertz microwave absorber and the free space is achieved; the reflection of the whole Salisbury screen flexible Terahertz microwave absorber structure is allowed to be smallest; and energy absorbed by the structure is converted into thermal energy in the surface-layer DAST organic material layer, so the Salisbury screen flexible Terahertz microwave absorber is allowed to acquire excellent Terahertz absorption performance.
Owner:UNIV OF ELECTRONICS SCI & TECH OF CHINA
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