127results about How to "Absorbing frequency bandwidth" patented technology

The invention discloses a flexible electromagnetic wave shielding and absorbing cloth and a production method thereof. The flexible electromagnetic wave shielding and absorbing cloth comprises a four-layer structure which sequentially comprises a chemical fiber fabric layer, an electromagnetic wave shielding layer, an electromagnetic wave absorbing layer and a flame-retardant and waterproof layer from bottom to top. The production method of the flexible electromagnetic wave shielding and absorbing cloth comprises the following steps: 1, drying the chemical fiber fabric; 2, preprocessing the chemical fiber fabric obtained in step 1; 3, plating the chemical fiber fabric obtained in step 2 with a layer of meta; 4, coating the metal layer plated chemical fiber fabric obtained in step 3 with a layer of a wave absorbing coating; and 5, coating the wave absorbing layer coated chemical fiber fabric obtained in step 4 with a layer of a flame-retardant and waterproof coating. The electromagnetic wave shielding and absorbing cloth has the advantages of wide wave absorption frequency band, high absorption intensity, flame retardation and waterproofing property, good flexibility, light weight and thin thickness, and can be applied to electromagnetic interference and electron strike prevention in the fields of electronic products and military devices.

The invention relates to a preparation method of a chromium-doped ferrous alloy wave-absorbing material. The preparation method comprises the following steps: mixing raw materials: Fe, Nd and Cr according to a certain atom ratio, melting the metals in an arc furnace; then sealing the alloy sample in a vacuum quartz glass tube, then placing the sealed quartz glass tube in a high-temperature environment to carry out a further homogenization treatment, quenching, taking out the alloy sample, mechanically and primarily grinding the alloy sample in a mortar, then transferring the alloy powder to a stainless steel ball-milling tank, carrying out high-energy ball milling under the protection of gasoline, after a while, pouring out the gasoline, taking out the alloy sample powder, drying the powder in the air so as to obtain the alloy micropowder wave-absorbing material.

The invention relates to the technical field of optical protection films, and especially relates to an electromagnetic-radiation-resistant protection film and a preparation method thereof. The preparation method comprises the following steps: step 1, preparing light-cure paint with electromagnetic radiation resistant function; step 2, coating a PET base material with the light-cured paint by using a slight-concave roller, and controlling the coating thickness of the light-cured paint to be 3-10 mu m, the diameter of the slight-concave roller to be 30-50 mm and the line screen of the slight-concave roller to be 40-400; step 3, curing the paint to obtain a film; and step 4, preparing the electromagnetic-radiation-resistant protection film. The electromagnetic-radiation-resistant protection film is good in electromagnetic-radiation-resistant effect, the technology is simple and manure and beneficial for popularization and application. When the electromagnetic-radiation-resistant protection film is used, the electromagnetic-radiation-resistant protection film can be attached to a handset or a display screen by tearing a PET protection film. Compared with electromagnetic-radiation-resistant equipment at home and abroad, such as radiation-proof clothes, electromagnetic-wave protection helmets and the like, the electromagnetic-radiation-resistant protection film is simple and convenient to use and easy to popularize.

The invention provides an alloy microwave absorbing material added with vanadium and a preparation method. The preparation method comprises the following steps: taking proper amounts of metal Fe, Nd and V of which the purities are higher than 99.5% respectively for dosage according to the atomic ratio of Fe17Nd2-xVx, wherein X is more than or equal to 0.1 and is less than or equal to 0.8; smelting into an alloy ingot by using a vacuum electric-arc furnace; performing vacuum sealing by using a quartz glass tube; inspecting the airtightness by soaking the glass tube in water; performing operations such as homogenization, quenching and mechanical preliminary pulverization; pouring the sample into a ball-milling jar, and performing ball-milling by using a planetary ball mill under the gasoline environment protection condition; pouring out the gasoline after the ball-milling is finished; taking out sample powder and drying, thus obtaining an alloy micro powder wave absorbing material.

The invention relates to the technical field of microwave absorption, in particular to a graphene-based ternary composite wave-absorbing material and a preparation method thereof. The preparation method comprises the steps of firstly, preparing silicon dioxide-coated carbonyl iron core-shell composite particles by using a sol-gel method, then preparing graphite oxide by using an improved Hummers method, evenly dispersing the graphite oxide into dispersion liquid of the silicon dioxide-coated carbonyl iron core-shell composite particles, and finally, using an ultrasonic reduction method to enable graphite oxide to be reduced into graphene so as to prepare the graphene-based ternary composite wave-absorbing material. The preparation method provided by the invention is simple and efficient; the prepared composite wave-absorbing material is more excellent in wave absorbing performance, high in wave absorbing strength, wide in wave absorbing bandwidth and smaller in density compared with a pure carbonyl iron binary composite wave-absorbing material and a pure graphene and carbonyl iron or graphene binary composite wave-absorbing material; the graphene-based ternary composite wave-absorbing material also has regulation performance, and can realize strong wave absorption under different frequencies by adjusting the thickness of a coating layer SiO2, the mass ratio of graphene to the coated core-shell composite particles and the thickness of the ternary composite material.

The invention relates to a broadband silicon carbide high temperature resistant wave-absorbing coating and a preparation method thereof, and mainly overcomes the problems of poor high temperature performance and complex process of conventional wave-absorbing coatings. The wave-absorbing coating takes silicon carbide micro powder as a main wave-absorbing agent; and wave-absorbing band is adjusted by controlling the proportions of silicon carbide in different morphologies. The preparation method comprises the steps of (1) preparation of a coating material: weighing the silicon carbide micro powder, oxide, a silicate binder, a surfactant and deionized water according to amounts, mixing the above raw materials and ball milling for 4 h to obtain the wave-absorbing coating material; (2) preparation of the coating: subjecting an alloy as a substrate to sand blasting treatment, then spraying a transition layer containing NiCr AlY on the substrate by a hot spraying method, spraying the prepared wave-absorbing coating material on the transition layer, drying the coating at a normal temperature, putting the coating into an oven for drying after the surface of the coating is dried, a drying temperature being 50-180 DEG C, subjecting the dried coating to heat treatment for 1-12 h at a temperature of 600-1,200 DEG C, and cooling the coating along with the oven to obtain the high temperature resistant wave-absorbing coating. The wave-absorbing band of the prepared wave-absorbing coating is mainly between 2 GHz and 20 GHz.

The invention provides a protein-based carbon/magnetic Fe Co nanoparticle composite wave-absorbing agent and a preparation method and application thereof, and belongs to the technical field of wave-absorbing materials. The preparation method of the protein-based carbon/magnetic Fe Co nanoparticle composite wave-absorbing agent comprises the following steps: 1) mixing water, ferric chloride hexahydrate, ferrous chloride tetrahydrate and cobalt chloride hexahydrate, and reacting for 1-2 h at the temperature of 70-100 DEG C to prepare magnetic nanoparticles; 2) mixing the magnetic nanoparticles with egg white liquid, and curing to obtain a protein-magnetic nanoparticle compound; 3) carbonizing the protein-magnetic nanoparticle compound obtained in the step 2) to obtain the protein-based carbon/magnetic Fe Co nanoparticle composite wave-absorbing agent. The material prepared by using the composite wave-absorbing agent has strong wave-absorbing performance, meanwhile has the characteristicsof wide wave-absorbing frequency band, small matching thickness of an absorber and the like, and has a large application prospect in the field of wave-absorbing materials.

The present invention provides a material with characteristics of fire retardation, thermal insulation and wave absorption. The material comprises a base layer, wherein the base layer is mesh fabric, both sides of the mesh fabric are coated with an adhesive coating layer, and the adhesive coating layer is a polyvinylchloride adhesive coating layer. The adhesive coating layer comprises a wave absorption agent, wherein the wave absorption agent comprises nickel-plated glass beads, and a mass ratio of the wave absorption agent powder to the adhesive is 0.17-1.85:1. The present invention further provides a preparation method for the material. According to the material with characteristics of fire retardation, thermal insulation and wave absorption in the present invention, the polyvinylchloride adhesive is added with the wave absorption agent, such that functions of fire retardation, thermal insulation and wave absorption can be concurrently provided; the material of the present invention can concurrently has functions of fire retardation and thermal insulation, and characteristics of high wave absorption strength, wide wave absorption frequency band, and small surface density; and the material of the present invention can be used for wave absorption defilading, electromagnetic shielding, and the like.

The invention provides a method for preparing a reduced graphene oxide/CoFe2O4/Ag composite wave-absorbing material. According to the method, RGO/CoFe2O4 is prepared by use of a hydrothermal method, and then the RGO/CoFe2O4/Ag ternary composite wave-absorbing material is prepared by use of a wet chemical method. The method is characterized in that no any surfactant is needed and also no insert gas such as nitrogen is needed for protection; the preparation process is simple and the preparation conditions are easy to implement.

The invention discloses a processing method of a wideband electromagnetic wave absorption suede fabric. The processing method comprises the following steps: weaving a dual-layer fabric by selecting and using conductive fiber blended yarns; diluting and uniformly mixing a wave absorbent with a flexible adhesive to prepare a wave absorption adhesive with good adhesion performance; soaking plush of a prepared one-sided suede fabric in the prepared wave absorption adhesive; performing pad-roll on the obtained suede fabric by a proper pressure and removing the excess wave absorption adhesive by extruding; baking the obtained suede fabric in a baking oven to prepare the special wideband electromagnetic wave absorption suede fabric. The wideband electromagnetic wave absorption suede fabric has the absorbed electromagnetic wave frequency range of 300 MHz to 40 GHz, can serve as an important biological health protection or facility safety protection product, and radically eliminates the harm caused by electromagnetic radiation.

The invention provides a rice husk based C/magnetic Co particle composite wave absorber and a preparation method thereof and belongs to the technical field of wave absorbing materials. Magnetic Co particles of the rice husk based C/magnetic Co particle composite wave absorber are 1.3 mu m in size, and rice husk based C also has a porous structure. The preparation method of the composite wave absorber comprises three steps: pretreatment: rice husk is washed with purified water and treated with HF (hydrofluoric acid), Si compounds in the rice husk are removed through etching, and the rice husk treated with the HF is obtained after drying; modification: the rice husk treated with the HF is soaked in a CoCl2 aqueous solution, water is removed through reduced-pressure distillation, and CoCl2 modified rice husk is obtained; carbonization: the CoCl2 modified rice husk is placed in a tube furnace and carbonized at a high temperature in an inert gas atmosphere, the carbonized material is further ground, and the rice husk based C/magnetic Co particle composite wave absorber is obtained. The prepared wave absorber has excellent wave absorbing performance and shows stronger absorbing characteristic on electromagnetic waves.

The invention discloses a low-temperature plasma generating device with a stealth function, comprising discharging patches, an electromagnetic transparent dielectric coating, a micropore, a carbon fiber discharge electrode and a metal conducting layer. A low-temperature plasma generating method with a stealth function, the discharging patches are uniformly installed on the outer surface of military equipment, and the discharging patches are connected with a high-voltage power supply; the high-voltage power supply is controlled to release pulse high voltage, the pulse voltage is connected witha carbon fiber discharge electrode, dielectric barrier discharge is carried out under the action of the electromagnetic transparent dielectric coating to release the plasma, and a plasma cloud clusteris formed. According to the device in the invention, the high-frequency high-voltage plasma generator is used for manufacturing the plasma, that is, under a high-frequency voltage condition, a dielectric barrier discharge mode is used to avalanche the air into plasma, and radar signals can be shielded.

The invention discloses a carbon coated nickel nanoparticle and silicon resin composite microwave absorbing coating and a preparation method thereof. The composite microwave absorbing coating is composed of 40%-60% by weight of carbon coated nickel nanoparticles and silicon resin. The preparation method comprises the steps that the carbon coated nickel nanoparticles are prepared through an arc discharge method; the carbon coated nickel nanoparticles are filled into the silicon resin to be evenly mixed, and coating slurry is obtained; an adequate amount of xylene is taken to serve as solvent to be added into the slurry, and the viscosity of the slurry is adjusted; a curing agent is added into the slurry, even stirring is conducted, and the coating with certain thickness is prepared. The composite microwave absorbing coating prepared through the method has the advantages of being wide in wave-absorbing band, good in wave-absorbing efficiency, low in reflectivity, high in stability, good in mechanical property and the like, the technology is simple, and the coating is easy to repair.

The invention discloses a broadband wave-absorbing material based on 3D printing. The material is formed by sequentially stacking a dielectric layer and a reflecting layer from outside to inside, and has a periodic three-dimensional structure. The dielectric layer is composed of an organic resin binder, ceramic powder and a wave-absorbing agent, the dielectric layer is of a three-dimensional periodic array structure, structural units are cylinders, cuboids, prisms or prismatic tables, the number of layers is 2-3, and the structural units are coaxially stacked from small to large from outside to inside, and the reflecting layer is made of metal, ceramic or a high-molecular compound. The preparation method of the broadband wave-absorbing material comprises the following steps: establishing a model, preparing powder, and preparing the material through 3D printing. According to the novel three-dimensional structure metamaterial, the integral structural strength of the wave-absorbing material is effectively improved, the adjustability of the wave-absorbing performance of the material is greatly improved, the wave-absorbing frequency band is widened, meanwhile, the manufacturing process is simple, the production efficiency is high, and batch production can be achieved easily.

The invention relates to a method for preparing a reduced-oxidized graphene/Cu2O/Cu quantum dot ternary wave-absorbing material. By taking sodium borohydride as a reducing agent, the RGO/Cu2O/Cu ternary composite wave-absorbing material is prepared by employing a simple wet chemistry method. The Cu2O and Cu have the size of less than 5nm and are directly loaded on an RGO nanosheet. The preparation method is simple and rapid, the compounding process is short in time consumption (only 4-6 hours), the preparation process is simple, the preparation conditions are easily realized, and large-scale production can be realized, and moreover, the large-scale production can be realized, the prepared composite material is good in wave-absorbing performance, and different wave bands can be effectively absorbed by adjusting the addition ratio of the GO and Cu<2+> and the thickness of the composite material.

According to the invention, Nd and La are added into a Fe base alloy to prepare microwave absorption micropowder with excellent performance, and the micropowder is characterized in that metal Fe, Nd and La are used as raw materials, burdening is performed according to an atom ratio of Fe17Nd2-xMnx (x is larger than or equal to 0.2 and is smaller than or equal to 0.7), operations of smelting, vacuum sealing, homogenization treatment, quenching and the like are performed to prepare the wave absorption alloy, then the alloy is mechanically preliminarily crushed, and is ball-ground with a planet type ball grinder under a gasoline environment protection condition, after ball grinding, the powder is collected and aired to obtain the wave absorption micropowder.

The invention provides a preparation method of a Fe-Nd-Al alloy microwave absorbing material. The preparation method comprises the following steps: preparing high-purity metals: Fe, Nd, and Al according to a certain atom ratio, adding the prepared Fe, Nd, and Al into an arc melting furnace to smelt the alloy, transferring the alloy to a quartz glass tube, vacuumizing and sealing the quartz glass tube, homogenizing and quenching the alloy, primarily and mechanically grinding the alloy in a grinding mortar, finally carrying out high-energy ball milling under the protection of gasoline, taking out the sample powder, and drying in the air so as to obtain the microwave absorbing material having the advantages of wide absorption frequency band, high absorption rate, and light weight.

The invention belongs to the technical field of wave-absorbing materials and discloses a resin column reinforced broadband wave-absorbing/bearing composite material and a preparation method thereof. The preparation method comprises the steps of sequentially stacking an impedance matching layer playing a role in impedance gradual change, a wave-absorbing layer containing an absorbent and a reflecting layer are on a lower portion of a wave-transmitting layer to form a laminated structure, and punching through holes in the formed laminated structure, enabling resin to flow into the through holesby adopting a wet forming process, and forming resin column structures penetrating through the whole laminated structure at the positions of the through holes. According to the invention, the throughholes are punched in advance in the thickness direction of a multi-layer structure prefabricated body, the process characteristics of wet molding of the composite material are used, the resin is poured into the through holes in the prefabricated body filling process to form Z-direction resin column structures, the effect of enhancing the interlayer performance is achieved, the forming process is simple, the mechanical property is excellent, the interlayer performance is greatly enhanced through the resin column structures formed at the through holes, and the defect that a current wave-absorbing composite material wave-absorbing layer is easily layered can be effectively overcome.

The invention provides a semi-active/full-active integrated type electromagnetic vibration absorber which comprises spring steel sheets, two rotors, two stators, an aluminum plate and a base. The upper end portions and the lower end portions of the two spring steel sheets are respectively fixed together to form a spring outer shell, wherein the two sides of the spring outer shell are arc in shape, and the middle of the spring outer shell is a line segment. The upper end portions of the two spring steel sheets are fixed together through an upper bottom plate, and the lower end portions of the two spring steel sheets are fixed together through a lower bottom plate. The aluminum plate and the upper bottom plate are fixed through an angle aluminum piece, the lower end of the aluminum plate and a guide shaft are fixed, the guide shaft is inserted into a linear bearing, and the linear bearing is fixed in a base. The two rotors are reversely fixed to the aluminum plate and located on the two sides of the aluminum plate respectively, the portions, on the two sides of the guide shaft, of the base are respectively provided with a stud, the two stators are arranged on the two studs respectively, the two stators and the two rotors are arranged in an opposite mode, exciting coils are wound on the rotors, and magnet exciting coils are wound on the stators. According to the semi-active/full-active integrated type electromagnetic vibration absorber, switching of semi-active operation and full-active operation can be achieved.

The invention relates to a preparation method of a metal doped carbon nanotube/polyvinyl chloride composite wave-absorbing film material. The method is characterized in that the method comprises the following steps: preprocessing carbon nanotubes by using a mixed acid, mixing a certain amount of lanthanum nitrate and the carbon nanotubes in an aqueous solution, carrying out ultrasonic treatment at a certain temperature for 1h, drying, and grinding to obtain a material for later use; and sequentially adding a certain amount of lanthanum nitrate doped carbon nanotubes, a plasticizer, a cross-linking agent and the like to a tetrahydrofuran solution of polyvinyl chloride, carrying out ultrasonic treatment, magnetically stirring for uniform mixing, injecting the obtained colloidal solution to a die, and drying at room temperature for 24h to obtain the rare earth doped carbon nanotube/polyvinyl chloride composite wave-absorbing film material. The preparation method of a composite wave-absorbing film is economic and suitable, and is simple to operate. The rare earth doping enhances the electromagnetic wave absorbing performance of multiwall carbon nanotubes in a 2-18GHz range.