605 results about "Electromagnetic wave absorption" patented technology

The invention provides a modified basalt fiber, a basalt fiber shielding material and a preparation method, and relates to the technical field of fiber composites.The modified basalt fiber comprises an activated basalt fiber, an adhesion layer and an electromagnetic shielding layer, and the surface of the activated basalt fiber is sequentially coated with the adhesion layer and the electromagnetic shielding layer; the adhesion layer comprises polydopamine; the electromagnetic shielding layer comprises magnetic Fe3O4 nano particles and a graphene nano sheet; the mass ratio of the activated basalt fibers to the polydopamine to the magnetic Fe3O4 nanoparticles to the graphene nanosheets is 1 to (0.4 to 0.5) to (0.6 to 1) to (0.1 to 0.25). According to the basalt fiber shielding material provided by the invention, the conductive particles and the magnetic particles are combined, and by optimizing the material components and proportion, a very good electromagnetic wave absorption and shielding effect can be achieved, a wider frequency band shielding effect can be provided, and electromagnetic radiation in various frequency ranges can be effectively covered.

The invention discloses supercritical fluid foaming polyimide wave-absorbing foam and a preparation method thereof.The thermoplastic polyimide is prepared by the steps that aromatic dianhydride, aromatic diamine and aliphatic diamine serve as comonomers, polyimide acid is generated through solution polymerization, and then high-temperature cyclization is conducted; wherein the mole number of the aliphatic diamine accounts for 10-50% of the total mole number of the diamine, and the free volume and glass transition temperature of a molecular chain are effectively regulated and controlled by introduction of the aliphatic diamine; the wave-absorbing foam is prepared by taking polyimide as a matrix, doping 1-20wt% of wave-absorbing filler, and foaming for 1-3 hours in a supercritical carbon dioxide or nitrogen environment at the temperature of 180-220 DEG C and the pressure of 9-25MPa, through molecular structure design, the adsorption capacity and impact resistance of polyimide to carbon dioxide are remarkably improved, and the prepared foam has the advantages of light weight, high porosity, uniform foam structure and excellent heat resistance, can realize effective electromagnetic wave absorption in an X wave band, and is suitable for the fields of aerospace stealth and electromagnetic compatibility protection.

The invention relates to the technical field of solid waste recycling and functional building materials, in particular to a wave-absorbing wall material based on a waste glass fiber wind power blade and a preparation method of the wave-absorbing wall material. The wave-absorbing wall material based on the waste glass fiber wind power blade is mainly prepared from the following raw materials in parts by mass: 60-68 parts of waste glass fiber wind power blade granules, 30-35 parts of silicon-aluminum solid wastes, 2-5 parts of a wave-absorbing reinforcing agent and 6-10 parts of water. According to the invention, waste wind power blades and silicon-aluminum solid wastes are used as raw materials, a high-strength porous carbon skeleton structure is formed in the material through a vacuum pugging molding and vacuum sintering process, and meanwhile, a ferrite wave-absorbing reinforcing agent is mixed to form a composite wave-absorbing electromagnetic structure of a carbon aggregate-dielectric loss material and a ferrite particle-magnetic loss material; collaborative optimization of the electromagnetic wave absorption performance and the material mechanical property is achieved, and good ecological value and economic benefits are achieved.

The invention belongs to the technical field of nano materials, and relates to a carbon thermal reduction driven high-entropy oxide metastable-state material and a preparation method and application thereof.The preparation method comprises the steps that S1, carbon and soluble metal salt are dissolved in a solvent for ultrasonic treatment, and a metal salt solution and a carbon suspension are obtained; s2, adding a metal salt solution into the carbon suspension, adding strong base, and stirring to obtain a coprecipitation polymer; s3, re-dispersing the coprecipitation polymer in the solvent, adding extra ferric salt and urea, mixing and stirring, and freeze-drying the mixed solution to obtain precursor powder; s4, performing staged annealing treatment on the precursor powder under low oxygen partial pressure to obtain a carbon-loaded high-entropy oxide metastable-state material; the prepared high-entropy oxide metastable-state material is of an alloy phase and high-entropy oxide double-phase coupling structure, the polarization loss of electromagnetic waves is enhanced through a heterogeneous interface, and the high-entropy oxide metastable-state material has the advantages of being excellent in impedance matching and wide in electromagnetic wave absorbing bandwidth and can be widely applied to the fields of industrial electronics, medical communication and military stealth.

The invention belongs to the technical field of electromagnetic wave functional materials, and particularly relates to a nested split ring wave-absorbing metamaterial and a preparation method thereof. The wave-absorbing metamaterial sequentially comprises an FSS metal structure layer, a dielectric layer and a metal matrix layer from top to bottom in the thickness direction, the FSS metal structure layer is formed by distributing structure units in a periodic array mode, each structure unit is composed of a double-opening outer ring shaped like a Chinese character'hui 'and a double-opening inner ring, the double-opening outer ring is a split square, and the double-opening inner ring is a hollow square. The structural units are symmetrically arranged about the diagonal line of the dielectric layer. The FSS metal structure layer designed by the invention has anisotropy, so that the polarization direction of an incident wave can be rotated by 90 degrees in a reflection mode. By means of the design, the two functions of electromagnetic wave absorption and polarization conversion are achieved at the same time, and meanwhile the effect of multiband wave absorption is achieved. Within the frequency band of 4 GHz to 18 GHz, the maximum wave-absorbing strength of the nested wave-absorbing metamaterial is as high as-30 dB, and the effective wave-absorbing bandwidth can reach 7.5 GHz.

The invention relates to the technical field of high-entropy ceramic powder, in particular to diboride high-entropy ceramic powder and a preparation method thereof.The preparation method comprises the following steps that five transition metal oxides, boron powder and fused salt serve as raw materials, are evenly mixed through a mixer and then are dried at the temperature of 60-200 DEG C, and a mixture is obtained; then, the mixture is put into a corundum crucible, and heat preservation is conducted for 1-20 h at the temperature interval of 700-1600 DEG C and under the protective atmosphere; and after the reaction is completed, cooling, washing, carrying out suction filtration, and drying at 60-200 DEG C to finally prepare the diboride high-entropy ceramic powder. The method has the advantages of low synthesis temperature, small product particle size, uniform element distribution, environment friendliness and the like, and the prepared diboride high-entropy ceramic powder shows excellent electromagnetic wave absorption performance.

The invention discloses a preparation method of a beaded cobalt-doped Bi25FeO40 / BiFeO3 nanofiber wave-absorbing material, which comprises the following steps: obtaining a precursor by a standing method, and adding the precursor, bismuth nitrate, ferric nitrate and a spinning aid into a mixed solvent compounded by N, N-dimethylformamide and absolute ethyl alcohol to obtain a spinning solution; spinning the spinning solution by adopting an electrostatic spinning technology to obtain a nanofiber membrane; and finally, drying and calcining to obtain the wave-absorbing material. According to the wave-absorbing material, multiple reflection and scattering of electromagnetic waves are increased, the absorption performance of the electromagnetic waves is improved, due to the fact that a heterogeneous interface is generated after two phases are compounded, the interface polarization loss is further increased, when the thickness of the wave-absorbing material is 2.33 mm, the minimum reflection loss reaches-56.01 dB, the effective absorption frequency band width is 6.32 GHz, and the whole Ku wave band is covered.

The utility model relates to a feed antenna and electronic equipment, the feed antenna comprises a main branch, a parasitic branch and a floor, the main branch is provided with a feed branch, the feed branch is connected with the floor, the parasitic branch is provided with a grounding branch, the grounding branch is connected with the floor, and the main branch and the parasitic branch are at least partially overlapped. According to the feed antenna, the electromagnetic wave absorption ratio of the front end facing the user to the rear end back to the user is low, and the degree of harm to the user is smaller.

The invention relates to a preparation method and application of a two-dimensional ultrathin porous nitrogen-doped carbon composite material. According to the invention, a metal salt nitrate ion mediation method is adopted, and the ultrathin porous carbon nanosheet loaded with metal single atoms and metal nanoparticles is successfully prepared through decomposition of a prepolymerized dopamine-metal salt precursor. By changing the type of metal salt ligand anions, accurate regulation and control between a non-porous structure and a porous structure can be realized. Endogenous multi-scale pore defects are introduced into the surface of the carbon nanosheet, so that the impedance matching of the prepared carbon nanosheet system is effectively improved, and meanwhile, high conductivity is kept. According to the prepared material, the dielectric constant is improved by introducing a porous structure, impedance matching is optimized, and the electromagnetic wave absorption capacity is improved.

The present invention provides: a powder which is capable of forming an electromagnetic wave absorption layer that has electromagnetic wave absorption characteristics in a wider frequency region than ever before and is suppressed in performance variation, and which can be electrostatically adhered or heat fixed to a support body; and an electromagnetic wave absorber which comprises a melt molded body of the powder as an electromagnetic wave absorption layer. The present invention provides: a powder which is capable of forming an electromagnetic wave absorption layer that has electromagnetic wave absorption characteristics in a wider frequency region than ever before and is suppressed in performance variation, and which can be electrostatically adhered or heat fixed to a support body; and an electromagnetic wave absorber which comprises a melt molded body of the powder as an electromagnetic wave absorption layer.

The invention discloses an electromagnetic wave absorbing material CoFe2O4 / ZnO-RGO with a ternary heterostructure as well as a preparation method and application of the electromagnetic wave absorbing material CoFe2O4 / ZnO-RGO, and belongs to the technical field of electromagnetic wave absorption. According to the material, a novel heterostructure with a multi-scale interface and a three-dimensional conductive network is constructed by compounding magnetic loss type CoFe2O4, dielectric loss type ZnO nanorods and resistance loss type RGO. Wherein the ZnO nanorod not only serves as a dielectric loss body, but also effectively enhances the structural anisotropy and the interface polarization effect of the material, and cooperates with the magnetic loss of CoFe2O4 and the resistance loss of RGO to jointly optimize impedance matching and improve the electromagnetic attenuation capability, so that the material shows excellent wave-absorbing performance under various thickness and even ultrathin conditions. The material source is wide, the cost is low, the preparation process is green, simple and convenient, the material is suitable for large-scale production, and an effective material solution is provided for electromagnetic wave absorption application in the national defense and civil fields.

The invention discloses an aerogel metamaterial capable of switching electromagnetic wave absorption and deflection reflection wave beam and a preparation method thereof, and the preparation method is characterized in that a metamaterial unit with a loose structure is arranged and comprises a first layer of rectangular pyramid, a second layer of quadrangular frustum pyramid, a third layer of quadrangular frustum pyramid and an internal pyramid cavity; the first layer of rectangular pyramid, the second layer of quadrangular frustum pyramid, the third layer of quadrangular frustum pyramid and the internal pyramid cavity are on the same center line; the bottom surface of the internal pyramid cavity is close to the bottom surface of the third-time quadrangular frustum pyramid, and the vertex of the internal pyramid cavity is close to the vertex of the first-layer quadrangular pyramid; the preparation method comprises the following steps: pouring mixed dispersion liquid containing conductive / magnetic functional components and cellulose microfibers into a mold manufactured according to a set structure, freezing, and then freeze-drying to obtain the metamaterial unit. The obtained aerogel metamaterial solves the problems that the effective absorption bandwidth of aerogel with adjustable electromagnetic wave absorption performance is difficult to substantially break through, and the aerogel cannot have both electromagnetic wave absorption performance and deflection reflection beam performance at the same time.

The application discloses a kind of high-entropy dual-phase sulfide and its preparation method and application, belong to electromagnetic wave absorbing material field.The application wants to solve how to enhance the weak interface polarization effect of high-entropy sulfide in electromagnetic attenuation problem.The application introduces Cu and Al metal elements into multi-metal sulfide by solvothermal and annealing method, and synthesizes a kind of six-component high-entropy sulfide wave-absorbing material (6-HES) with dual-phase structure, wherein all metal elements are uniformly distributed in M9S8 and MS (M represents metal element) two phases with crystal lattice defects.The high-entropy dual-phase sulfide prepared by the method has heterogeneous interface structure and rich vacancy defects, which not only can improve its conductance loss, but also can enhance defect-induced polarization and interface loss.The application taps the potential of multi-metal sulfide in the field of electromagnetic attenuation.

The invention belongs to the technical field of hydrophobic electromagnetic shielding materials, and particularly relates to an asymmetric electromagnetic shielding composite film and a preparation method and application thereof. The PNTs are polypyrrole nanotubes, after Na2MoO4. 2H2O and CH4N2S are added and subjected to a high-temperature reaction, a MoS2 flower-shaped shell structure can grow on the PNTs, the layered structure and the high specific surface area of MoS2 contribute to enhancing scattering and absorption of electromagnetic waves, and rich defect sites can induce dielectric polarization to achieve dielectric loss. Introducing the PNTs (at) MoS2 core-shell nanowire as an electromagnetic wave absorbent into a polylactic acid / dichloromethane system, then putting the system into a culture container in which a conductive filler is pre-paved, and standing and volatilizing at room temperature by adopting an ethanol solution as a volatile agent to finally obtain a three-layer asymmetric electromagnetic shielding composite film comprising the conductive filler, the PNTs (at) MoS2 structure and a polylactic acid matrix from bottom to top. And an asymmetric conductive gradient network is constructed, and the EMI shielding performance which mainly focuses on absorption is remarkably improved, so that the secondary radiation problem of electromagnetic waves is reduced.

The invention relates to the technical field of electromagnetic shielding materials, and particularly discloses an electromagnetic shielding composite material with active and passive infrared stealth functions and a preparation method thereof. The composite material comprises an electromagnetic wave reflecting layer and a plurality of electromagnetic wave absorbing layers. The electromagnetic wave reflecting layer is made of silver-plated bacterial cellulose, and efficient reflection of electromagnetic waves is achieved through high conductivity of the silver-plated bacterial cellulose. The electromagnetic wave absorbing layer is formed by compounding bacterial cellulose, multi-walled carbon nanotubes and core-shell magnetic nanoparticles, and the content of the multi-walled carbon nanotubes is gradually decreased and the content of the core-shell magnetic nanoparticles is gradually increased from the position close to the electromagnetic wave reflecting layer to the outside, so that a gradient structure is formed; the gradient design can improve surface impedance matching, promote electromagnetic waves to enter the material, and enhance electromagnetic loss through an interlayer multiple reflection-absorption process. The material disclosed by the invention has the functions of efficient electromagnetic shielding and active and passive infrared stealth.

The invention relates to a preparation method of an infrared stealth and wave-absorbing material and the infrared stealth and wave-absorbing material.The preparation method of the infrared stealth and wave-absorbing material comprises the steps that PMMA microspheres are coated with Ti < 3 > C < 2 > T < x >, and PMMA-coated Ti < 3 > C < 2 > T < x > is obtained; the PMMA microspheres in the PMMA coated Ti < 3 > C < 2 > T < x > are removed, and hollow Ti < 3 > C < 2 > T < x > is obtained; growing ZnO on the hollow Ti < 3 > C < 2 > T < x > to obtain a first substance; the first substance is dispersed in a cellulose nanofiber suspension with the concentration of 5 mg / mL, vacuum filtration and drying are carried out, the infrared stealth and wave-absorbing material is obtained, and 0.5 g to 1 g of the first substance corresponds to 20 mL of the cellulose nanofiber suspension. The infrared stealth and wave-absorbing material prepared by the method has excellent electromagnetic wave absorption performance and good infrared stealth performance.

This invention provides a benzene-azo group-grafted polyhydroxy graphene oxide-based material and its application in electromagnetic wave absorption. The material is synthesized using aniline compounds and polyhydroxy graphene oxide as raw materials via diazo coupling. The feasibility of the preparation method was verified by spectral characterization, demonstrating the feasibility of impedance matching through covalent grafting of functionalized functional groups. This preparation method is simple, low-cost, and yields high output.

The application provides a hollow carbon / Co efficient electromagnetic wave absorbing material and a preparation method and application thereof, and comprises the following steps: step 1, dissolving cobalt nitrate hexahydrate, tetradecyl trimethyl ammonium bromide, 2-methyl imidazole and zinc nitrate hexahydrate in water, stirring and reacting to obtain solution C; step 2, washing solution C, separating and drying a solid product to obtain a hollow ZIF-8 / ZIF-67 precursor; and step 3, carbonizing the hollow ZIF-8 / ZIF-67 precursor under an inert atmosphere to obtain the hollow carbon / Co efficient electromagnetic wave absorbing material. The preparation process is simple, the material can be prepared on a large scale, and the prepared composite material has excellent electromagnetic wave absorbing performance.

The invention discloses a Ni3Sn2S2-coated FeCoCrNiAl composite powder electromagnetic wave absorbent, which is formed by compounding Ni3Sn2S2 and a FeCoCrNiAl high-entropy alloy, the core is FeCoCrNiAl, and the shell layer is uniformly coated Ni3Sn2S2, and the Ni3Sn2S2-coated FeCoCrNiAl composite powder electromagnetic wave absorbent is formed by compounding Ni3Sn2S2 and FeCoCrNiAl high-entropy alloy. And a core-shell or heterogeneous nano composite structure is formed. The invention also discloses a preparation method of the electromagnetic wave absorbent. The mass fraction of the Ni3Sn2S2 is 10%-40%, and the mass fraction of the FeCoCrNiAl high-entropy alloy is 60%-90%. When the Ni3Sn2S2 and the FeCoCrNiAl high-entropy alloy are compounded, the magnetic dielectric coupling effect generated between the Ni3Sn2S2 and the FeCoCrNiAl high-entropy alloy remarkably improves the overall impedance matching, the reflection loss is reduced, and meanwhile dual energy attenuation is achieved through the magnetic loss brought by the high-entropy alloy and the dielectric dissipation of the Ni3Sn2S2.

A composite electromagnetic wave-absorbing material and preparation method therefor are provided. The composite electromagnetic wave-absorbing material includes following raw materials: magnetite powder, nickel powder, copper powder, samarium oxide, gadolinium oxide, cerium oxide, carbon black powder, graphite powder, epoxy resin, barium titanate powder, antioxidant, curing agent, diluent and leveling agent. Ferrite wave-absorbing materials are used as matrixes to be compounded with nickel powder, copper powder, graphite powder, carbon black and barium titanate, and doped with mixed rare earth oxides through combination of samarium oxide, gadolinium oxide and cerium oxide to thereby obtain the composite electromagnetic wave-absorbing material which combines magnetic loss characteristics of magnetite powder, ferromagnetic behavior of nickel powder and conductivity of copper powder, helping to achieve good electromagnetic wave-absorbing performance. By introducing graphite powder, carbon black powder and barium titanate powder as fillers and doping rare earth, wave-absorbing characteristics of the composite electromagnetic wave-absorbing material are improved.

The invention belongs to the technical field of electromagnetic wave absorbing materials, and particularly relates to a wave absorbing material and a preparation method and application thereof. Multi-walled carbon nanotubes (MWCNT), potassium permanganate (KMnO4) and a divalent manganese source are used as raw materials, in-situ uniform loading of MnO2 nanoparticles on the surface of the MWCNT can be realized through simple stirring in a room-temperature liquid-phase environment based on an oxidation-reduction reaction between Mn < 2 + > and MnO4 <->, and the wave-absorbing property of the MnO2-loaded MWCNT wave-absorbing material is superior to that of most similar wave-absorbing materials. Compared with a preparation method of a traditional wave-absorbing material, the technical route has the remarkable advantages that the preparation process is easy and convenient to operate, no pollutant is discharged, the process is energy-saving and environment-friendly, the material structure is adjustable and controllable, the wave-absorbing performance is excellent, and large-scale application can be achieved. According to the method, the technical limitation in the preparation process of the wave-absorbing material is effectively broken through, and a brand new scalable normal form is provided for green and large-scale production of the high-performance wave-absorbing material.

The invention belongs to the technical field of electromagnetic wave absorbing materials, and discloses a composite coating with electromagnetic protection and explosion-proof functions as well as a preparation method and application of the composite coating. The coating comprises 40 to 60 parts of polycarbodiimide modified diphenylmethane diisocyanate, 40 to 60 parts of a semi-prepolymer which is synthesized from polycarbonate diol with the equivalent weight of 1000 and has the NCO content of 10 to 20 percent, 73 to 100 parts of a polyether amine curing agent, 15 to 20 parts of diethyl toluenediamine or dimethyl thio toluenediamine, 0.5 to 2 parts of calcium carbonate and 3 to 6 parts of magnetic powder. And the two components are quickly reacted and molded through a spraying process. According to the invention, the polyurea elastomer is used as a matrix, so that the coating is endowed with excellent impact resistance, explosion-proof characteristics, water impermeability, oil resistance, low temperature resistance and other environmental tolerance; meanwhile, an adjustable electromagnetic wave absorption function is realized by doping specific magnetic powder. The coating is simple in preparation process and excellent in comprehensive performance, and is particularly suitable for equipment surfaces with high requirements on stealth and survival protection, such as oil storage equipment.

The invention relates to the technical field of electromagnetic wave absorbing materials, in particular to a composite material and a preparation method and application thereof. The composite material is prepared from magnetic microspheres, modified SiO2 aerogel and Mxene, wherein the magnetic microsphere comprises an inner core and a coating layer, the inner core comprises Fe3O4, the surface of the inner core is at least partially coated with the coating layer, and the coating layer comprises SiO2; a modified group of the modified SiO2 aerogel comprises at least one of amino, hydroxyl and carboxyl; the magnetic microspheres are positioned on the two-dimensional surface of the MXene. According to the composite material, through the synergistic effect of the magnetic microspheres, the modified SiO2 aerogel and the MXene, impedance matching between the composite material aerogel and air is remarkably enhanced, and the electromagnetic wave absorption performance of the composite material is promoted.

The application discloses a multi-dimensional structure silicon carbide-silicon nitride composite material and a preparation method thereof. S As the core of the multi-dimensional structure, the prepared silicon carbide-silicon nitride composite material not only solves the long-term technical problems of'single dimension' and 'incomplete carbonization and nitridation', but also realizes the structural and functional integration of'mechanical strength and toughness' and 'electromagnetic wave absorption function', has the advantages of high purity, excellent mechanical properties, good electromagnetic wave absorption effect, low raw material cost, industrializable process and the like, and has a wide industrialization prospect.

The invention relates to a preparation method and application of a CoNi alloy nanoparticle doped double-shell hollow carbon material, and belongs to the field of nano material preparation technology and electromagnetic wave absorption application. 3-aminophenol and formaldehyde are subjected to a condensation polymerization reaction to synthesize phenolic resin balls, the phenolic resin balls are placed in 3-aminophenol and formaldehyde again to react, and the double-shell hollow phenolic structure is obtained. And adding the double-shell hollow phenolic aldehyde structure into cobalt nitrate hexahydrate (Co (NO3) 2.6 H2O) and 2-methylimidazole for low-temperature reaction, then adding a solution of (Ni (NO3) 2.6 H2O) for reaction at high temperature and high pressure, and drying to obtain the CoNi alloy nanoparticle doped double-shell hollow carbon material. According to the preparation method disclosed by the invention, the double-shell structure is taken as a main template, and the CoNi alloy nanoparticles are used as active components to be doped in the double-shell hollow structure in situ, so that the cascade synthesis of the microstructure of the nano material is greatly enriched, and the obtained CoNi alloy nanoparticle doped double-shell hollow carbon material has excellent electromagnetic wave absorption performance.

The application relates to an in-situ composite preparation method of a calcium phosphate / boron nitride high-temperature wave-absorbing material and application thereof, and belongs to the technical field of wave-absorbing materials. The method solves the problem that traditional insulator materials boron nitride have no electromagnetic wave absorption capacity. The method comprises the following steps: preparing Ca3(PO4)2 ion oligomers; preparing Ca3(PO4)2 ion oligomer gel; preparing a transparent hot solution of melamine diboric acid, then mixing the transparent hot solution of melamine diboric acid with the Ca3(PO4)2 ion oligomer gel, and then cooling, centrifuging, drying and sintering, so that the preparation is completed. The calcium phosphate / boron nitride high-temperature wave-absorbing material is prepared by adopting the in-situ composite mode, the process is simple, the cost is low, the process is green and pollution-free; the wave-transparent boron nitride material is converted into a wave-absorbing material through the simple composite of inorganic non-metallic substances, the balanced magnetic property and polarization effect of the material are matched with each other, high-strength and wide-band electromagnetic wave absorption performance is finally realized, and meanwhile, the lightweight and high-temperature-resistant characteristics of boron nitride are maintained.

The invention provides a ZrO2 (at) SiC (at) NiCo2O4 / NiO composite material with high temperature tolerance and a preparation method and application thereof, the composite material takes ZrO2 (at) SiC fibers as a three-dimensional conductive network framework, and NiCo2O4 / NiO nanosheets are anchored on the surfaces of the ZrO2 (at) SiC fibers. The composite material shows excellent electromagnetic wave absorption performance in a high-temperature environment.

The invention discloses an on-line radiation monitoring and power-off protection MEMS pressure sensor and a preparation method thereof. The sensor can synchronously realize pressure measurement, radiation monitoring and power-off protection functions on a single chip. On the basis of realizing high-precision pressure measurement, the sensor is provided with a platinum film resistor in a specific area and is coated with an electromagnetic wave absorbing material to form a radiation sensing unit, so that the on-line monitoring on the electromagnetic radiation intensity of the environment is realized. The protection circuit closely integrated with the sensor continuously analyzes radiation dose signals, and once it is judged that the dose exceeds a preset safety threshold value, a control signal is generated, a power supply access of the pressure measurement unit is actively cut off, the pressure measurement unit is made to enter a dormant state, and therefore irreversible performance degradation or permanent damage is avoided. According to the invention, the conversion from passive bearing to active protection during the working of the sensor is realized, and the reliability of long-term working in an extreme electromagnetic environment is obviously improved.

The invention discloses a three-dimensional structure electromagnetic regulation and control material and a preparation method thereof, and belongs to the technical field of electromagnetic functional composite materials. In order to solve the problems of narrow band wave absorption and high density of a traditional electromagnetic regulation and control material, spherical carbonyl iron powder, conductive carbon black, graphene, carbon nanotubes, methyl vinyl silicone rubber and hydrophobic fumed silica are used as an electromagnetic regulation and control base material system, and the electromagnetic regulation and control material is prepared through mixing, vulcanization, forming and secondary processing. And the electromagnetic regulation and control material with the three-dimensional periodic tower-shaped microstructure, which has broadband electromagnetic wave absorption and low density and can be flexibly attached, is prepared.

A device (100) for heating by electromagnetic waves comprises: an electrically conductive housing (1); an electromagnetic wave generation unit (10) that generates electromagnetic waves which are linearly polarized waves; a plurality of radiating units (3) that radiate the electromagnetic waves generated by the electromagnetic wave generation unit into the interior of the housing; a directivity control unit (2) that controls the directivity of the electromagnetic waves from the plurality of radiating units; and an electromagnetic wave absorbing unit (5) that is arranged inside the housing in such a way that the electromagnetic wave absorbing unit is aligned with a plane of oscillation of the electromagnetic waves and absorbs electromagnetic waves inside the housing.