74results about How to "Improve electromagnetic absorption performance" patented technology

The invention discloses a CoNi/porous carbon microwave absorbent with adjustable ratio, and also discloses a preparation method of the CoNi/porous carbon microwave absorbent with adjustable ratio, which includes the following steps: dissolving cobalt salt and nickel salt in seaweed NaCl aqueous solution, stirred for 24 hours, centrifugally washed and dried to obtain the precursor; the precursor was calcined in nitrogen, the cobalt-nickel ions were reduced to metal, and alloy grains of different proportions were formed according to the feeding ratio, and the carbon bonds of the disconnected It is rearranged around the alloy grains, and under certain temperature conditions, a porous carbon composite structure in which CoNi nano-alloy particles are uniformly embedded is formed. The preparation method of the invention has the advantages of simple preparation process, low cost, large output and simple synthesis equipment, and is suitable for large-scale industrial production.

An electromagnetic wave absorbing silicon-carbide particle coated by baruim ferrite film is prepared by citrate sol-gel method, that is, proportionally coating the barium ferrite film on the surface of silicon carbide particle. It can be used for wave absorbing coating.

Disclosed is a composite material for shielding broadband electromagnetic waves and a method for its production. More particularly, a composite material for shielding broadband electromagnetic waves that absorbs low frequency electromagnetic waves and reflects high frequency electromagnetic waves is disclosed. The composite material for shielding broadband electromagnetic waves may be a polymer composite prepared by mixing a matrix composition including a matrix-forming polymer impregnated with a carbonaceous conductive nano material with a filler composite including a filler-forming polymer impregnated with a magnetic material. The magnetic material impregnated in the filler-forming polymer may be distributed in the matrix composite.

The invention provides a heat-conducting and wave-absorbing material and a preparation method thereof, wherein the heat-conducting and wave-absorbing material is prepared from the following raw materials by weight: 200-400 parts of vinyl organosilicon, 150-550 parts of Si-H organosilicon, 0.1-5 parts of hydrogen-containing silicone oil, 50-400 parts of iron-silicon aluminum alloy magnetic powder,20-300 parts of SiO2 powder, 0.1-10 parts of a silane coupling agent, 0.005-0.5 part of a platinum catalyst, and 20-500 parts of a solvent. According to the present invention, the specific componentsare matched according to the specific ratio, such that the obtained heat-conducting and wave-absorbing material can excellent absorb K[alpha] electromagnetic waves so as to produce good electromagnetic absorption, and further has good thermal conductivity and good physical and mechanical property so as to easily achieve the normal operation of electronic equipment and improve the service life of the electromagnetic material.

The invention discloses a method for preparing UV light-catalyzed carbon fiber grafted polyaniline. The method comprises the following steps: soaking chopped carbon fibers in ammonium persulfate/ferrous chloride, stirring for certain time, washing, and vacuum-drying to obtain oxidized chopped carbon fibers; pre-modifying the oxidized chopped carbon fibers with dopamine; and placing dopamine-modified carbon fibers and ammonium persulfate in a dopamine hydrochloride solution and grafting the surfaces of the dopamine-modified carbon fibers with polyaniline under irradiation of a UV lamp. In the method, the number of surface active groups of the fibers is increased firstly through oxidation, then the surfaces are modified with dopamine, and the polyaniline is polymerized to be grafted onto the surfaces of the fibers under catalysis of ultraviolet light, so that improvements on wettability and reactivity with a matrix in the later stage are favorable, and the electromagnetic wave absorption performance is greatly improved. The method has the advantages of being mild in conditions, high in grafting efficiency, relatively stable in polyaniline on the surfaces of the fibers, and capable of improving poor bonding strength with the matrix, low adhesion and the like, and is favorable for improving the performance of a carbon fiber reinforced composite material.

The invention relates to a rapid preparation method of a high-temperature-resistant structured wave-absorbing ceramic matrix composite material. The SI+RMI process is adopted to prepare a SiC fiber-reinforced silicon-based ceramic matrix composite material. Firstly, Si3N4 powder, BN powder, SiC powder, or C + Si3N4 mixed powder is respectively introduced into a SiC fiber preform through the SI process; and then, through the RMI process, a silicon melt is infiltrated into the composite material to be combined with or react with the above powder respectively so as to generate a Si3N4-Si matrix,a Si-B-N matrix, a SiC-Si matrix or a Si-C-N matrix, and an electromagnetic impedance matching type matrix (such as Si3N4-Si, Si-B-N, etc.) or an electromagnetic wave-absorbing type matrix (such as SiC-Si, Si-C-N, etc.) which meets the requirements of the structure wave-absorbing ceramic matrix composite material is prepared. Rapid densification of the composite material is realized, preparation cycle of the composite material is effectively shortened, and density and mechanical/wave-absorbing properties of the composite material are improved.

The invention relates to an MXene/Ni composite material as well as a preparation method and application thereof. The MXene/Ni composite material comprises an MXene carrier and nickel balls compoundedon the MXene carrier, wherein the nickel balls are distributed on the surface and between layers of the MXene carrier, the particle sizes of the nickel balls are not larger than 1 micron, and the MXene carrier is Ti<3>C<2>T<x>. According to the MXene/Ni composite material provided by the invention, the nickel balls are uniformly loaded on the surface and between layers of the MXene material, so the agglomeration phenomenon of particles is improved, the specific surface area of the material is increased, an interface between the materials is increased, wave-absorbing capacity at low frequency bands from 2 GHz to 18 GHz is enhanced, the maximum absorption (reflectivity) of electromagnetic waves reaches -47.06 dB, and excellent wave-absorbing capacity is shown.

The invention discloses a 3D printing electromagnetic wave absorption concrete orientated fiber classified feeding system. The 3D printing electromagnetic wave absorption concrete orientated fiber classified feeding system comprises a control unit and a first-stage stirring unit used for preliminarily weighing, mixing and stirring dry materials and wet materials, and further comprises a second-stage stirring unit, a fiber orientating unit and a third-stage stirring unit; the second-stage stirring unit comprises a middle-sized stirring barrel, an impeller rotation shaft, a middle-sized impellerand an auxiliary impeller and a coaxial reversing device thereof, the lower portion of the middle-sized stirring barrel is a revolution body of which the section is gradually decreased, the impellerrotation shaft is arranged in the axial direction of the middle-sized stirring barrel, the middle-sized impeller is arranged on the portion, located in the middle-sized stirring barrel, of the impeller rotation shaft, and the coaxial reversing device is coaxially connected to the upper portion of the impeller rotation shaft; and the fiber orientating unit comprises three solenoids, the three solenoids are sequentially arranged on the outer surface of the lower portion of the middle-sized stirring barrel in a surrounding mode from top to bottom, and each solenoid is independently connected witha corresponding switch circuit. According to the 3D printing electromagnetic wave absorption concrete orientated fiber classified feeding system, classified feeding of electromagnetic wave absorptionconcrete can be completed, magnetic fibers in the concrete can be output in an orientated mode, and 3D printing is achieved.

The invention discloses a method for microwave-assisted low-temperature rapid synthesis of ferrite ultrafine powder. The method comprises the steps of respectively weighing metallic oxide of Me, ZnO and Fe2O3 depending on chemical dosage of ferrite Me(1-x)ZnxFe2O4, mixing and wet-ball milling, drying and filtering by a 100-mesh sieve to obtain a mixture; and adding the mixture in a microwave reaction furnace, carrying out microwave-assisted solid synthesis for 10-30min in an air atmosphere at 600-950 DEG C, and cooling to obtain the ferrite ultrafine powder, wherein the Me is Ni, Mn or Co, and x is not greater than 1.0 and not less than 0. The process for microwave-assisted low-temperature rapid synthesis of the ferrite ultrafine powder is simple, high in temperature raising speed, short in heat preservation duration, low in synthesis temperature and excellent in performance, and is capable of effectively reducing production cost and energy consumption, and improving the production efficiency. And the method is applicable to mass production.

The invention discloses a high-entropy alloy wave-absorbing material with a reflection loss reaching -60.9dB. A molecular formula of the high-entropy alloy wave-absorbing material is FeNiCr<c>Al<d>, wherein a, b, c and d respectively represent atomic percent values of corresponding metal elements. The invention further discloses a preparation method for the wave-absorbing material. The method comprises the following steps of: 1, weighing raw material powder according to a target product; 2, filling the powder into a glove box filled with argon, and conducting sealing; 3, conducting ball milling; and 4, taking out a ball mill tank, and placing the ball mill tank in the glove box filled with the argon for opening to obtain the high-entropy alloy wave-absorbing material. For the high-entropy alloy wave-absorbing material disclosed by the invention, through the composition characteristics of multiple elements, the coupling effect of multiple loss mechanisms is exerted, so that the wave-absorbing performance of the high-entropy alloy wave-absorbing material is cooperatively improved, an effective absorption bandwidth is relatively large, energy consumption is relatively low, and the raw material cost is reduced. The preparation method disclosed by the invention is simple in process operation without complex equipment, low in cost and beneficial to large-scale production.

The invention provides a preparation method of an MOF-derived composite wave-absorbing material. The preparation process is simple, the cost is low, large-scale mass production can be realized, and the prepared wave-absorbing material has good impedance matching, wide effective absorption bandwidth and high reflection loss value. The ordered porous wave-absorbing material is synthesized by taking MOFs as a template, and magnetic metal, alloy or metal oxide generated after calcination can bring excellent magnetic loss, which is beneficial to impedance matching and wider effective absorption bandwidth.

The invention relates to the technical field of ceramic material preparation, in particular to a polymer precursor porous magnetic ceramic system based on a 3D printing technology, which comprises a slurry preparation unit, a 3D printer and a calcining boiler, the slurry preparation unit comprises a pretreatment tank and an ultrasonic stirring kettle; the pretreatment tank is used for preparing amodified pore-forming agent, the ultrasonic stirring kettle is used for adding the modified pore-forming agent, magnetic nanoparticles, an inert filler and a polymer precursor into an organic solventfor stirring and mixing, and the organic solvent is volatilized through ultrasonic treatment to obtain printing slurry; the 3D printer uses the printing slurry for printing to obtain a green body ; and the green body is calcined by a calcining boiler to obtain a porous magnetic ceramic. The preparation method is used for preparing the porous magnetic ceramic and comprises the following steps: A, preparing the slurry; b, preparing the green body; and c, performing atmospheric sintering. The preparation process is simple, the production cost is low, and the economic value of the prepared productis high.

The invention discloses a core-shell heterostructure magnetic nanowire as well as a preparation method and application thereof and belongs to the technical field of nanowire materials. The core-shell heterostructure magnetic nanowire takes an iron nanowire as a core and takes silver as a shell, is prepared by combining a magnetic field-assisted induction liquid phase reduction method and a layer-island growth mode, and has excellent electrical conductivity, oxidation resistance, corrosion resistance and wave-absorbing performance. A molar ratio of Fe to Ag in a ferromagnetic nanowire in the core-shell heterostructure magnetic nanowire is 1 to (0.3-1.1); the minimum reflection loss reaches -58.69dB, and the effective absorption bandwidth with the reflectivity being smaller than or equal to -10dB is 5.78-13.10GHz. The core-shell heterostructure magnetic nanowire has the advantages of mild conditions, simple equipment, good repeatability, short period and large-scale production, and has wide application prospects in the aspects of microwave absorption, electro-catalysis, flexible transparent conductive films and surface enhanced Raman spectroscopy.

The invention discloses a high-entropy alloy/carbon black composite electromagnetic wave-absorbing material which is characterized in that the molecular formula of high-entropy alloy/carbon black is (FeNiCrAla) xCy, a is the molar ratio of Al to Fe, Ni and Cr, x and y are the mass fraction of FeNiCrAla and the mass fraction of C in the high-entropy alloy/carbon black respectively, Fe, Ni, Cr and Al form a quaternary high-entropy alloy which is compounded with carbon black, magnetic loss and electric loss are both achieved, and the high-entropy alloy/carbon black composite electromagnetic wave-absorbing material has a good electromagnetic wave-absorbing effect. The wave absorbing performance of the material is effectively improved, and the material has broadband efficient electromagnetic wave absorbing performance and is widely applied to various civil and military electromagnetic wave absorbing fields; in addition, the invention further provides a preparation method of the high-entropy alloy/carbon black composite electromagnetic wave-absorbing material, according to the method, metal iron, metal nickel, metal chromium, metal aluminum and carbon black are subjected to high-energy ball milling, alloying and compounding, and preparation of the high-entropy alloy/carbon black composite electromagnetic wave-absorbing material is achieved.

The invention discloses a CoFe/C-CNT wave-absorbing material as well as a preparation process and application thereof. The invention relates to a preparation process of a CoFe/C-CNT wave-absorbing material. The preparation process comprises the following steps: S1, mixing Co (NO3) 2.6 H2O and Fe (NO3) 3.9 H2O to prepare a solution A; s2, dissolving 2-methylimidazole to prepare a solution B; s3, adding the solution A into the solution B, stirring, filtering, washing and drying to obtain an MOFs precursor; and S4, sintering the MOFs precursor prepared in the step S3 in a protective atmosphere, so as to prepare the CoFe/C-CNT material. According to the preparation process of the CoFe/C-CNT wave-absorbing material, the CoFe/C-CNT wave-absorbing material with excellent wave-absorbing performance is prepared, and the problem that current electromagnetic wave pollution is harmful to information, communication and human bodies can be solved.

The invention relates to a photovoltaic module with an electromagnetic shielding function. The photovoltaic module comprises a back plate, a lower EVA film, a solar cell, an upper EVA film and a glasscover plate. A side, close to the solar cell, of the back plate is coated with an electromagnetic shielding coating, and the glass cover plate is infrared reflection insulating glass. The electromagnetic shielding coating is prepared by the coating of electromagnetic shielding paint, and the photovoltaic module can effectively shield the electromagnetic radiation on the back and has high runningstability.

The invention relates to a recycled fine aggregate aerated building block with electromagnetic wave absorption performance. The recycled fine aggregate aerated building block comprises the following raw materials in parts by weight: 100-250 parts of recycled concrete aggregate fine powder, 50-100 parts of sand, 70-100 parts of cement, 30-50 parts of lime, 0.5-0.8 part of graphite, 0.5-1.0 part ofcarbon black, 20-30 parts of lightweight aggregate, 0.8-1.6 parts of polyurethane hot melt slag, 0.01 part of industrial carbon nanotube, 20-30 parts of steel slag powder, 0.4-0.5 part of aluminum powder, 0.7-1 part of carbon fiber, 3-6 parts of dispersant and 300-400 parts of water. The aerated building block has the advantages of low carbon, energy conservation, environmental protection, light weight, heat preservation and electromagnetic wave absorption performance; simple preparation method and convenience in construction are achieved; and the proportion of the components can be adjusted according to the wave absorption requirement, different reflectivity can be obtained, and various building external maintenance walls with radiation protection and heat preservation and insulation functions can be met.

The invention belongs to the technical field of nanophase material preparation, and provides a Fe nanometer dot @ BN nanosphere compound and preparation method thereof. The compound microstructure isthat the Fe nanometer dot is embedded in the BN nanosphere. The invention further discloses a preparation method for the Fe nanometer dot @ BN nanosphere compound. Plasma arc discharge method is adopted. Iron powder and boron powder are pessed into a block as an anode target material according to a certain percentage of atoms, tungsten is adopted as a cathode material, and argon and nitrogen are adopted as working gases; liquid nitrogen cooling stave is positioned around anode, certain distance is kept between cathode tungsten electrode and an anode iron-boron powder block; arc discharge is conducted between the anode and cathode; and the Fe nanometer dot @ BN nanosphere compound is obtained on the liquid nitrogen cooling stave, and a microwave absorption coating manufactured by the nanometer compound has excellent electromagnetic absorption property in the range of 2-18 GHz. The preparation process is simple, postprocessing is omitted, the cost is low and industrial production is easyto realize.

The invention belongs to the technical field of nanomaterial preparation. The invention discloses a Cu nano point@BN nanosphere compound and a preparation method thereof. A microstructure of the compound is formed by embedding nano points into BN nanospheres. The invention further discloses a preparation method of the Cu nano point@BN nanosphere compound. The preparation method is characterized inthat by adopting a plasma arc discharge process, copper powder and boron powder are pressed into a block according to a certain atomic percent to act as an anode target material, tungsten acts as a cathode material, argon and nitrogen are adopted as working gas, a liquid nitrogen cooling wall is placed around the anode, a certain distance is kept between a cathode tungsten electrode and an anodecopper-boron powder block body, and arc discharge is performed between the anode and the cathode, so that the Cu nano point@BN nanosphere compound is obtained on the liquid nitrogen cooling wall. A wave suction coating made of the Cu nano point@BN nanosphere compound has good electromagnetic absorption performance within a range of 2-18 GHz. The preparation process is simple, no post treatment process exits, the cost is low, and industrialized production is easy to achieve.