237results about How to "Absorption Bandwidth" patented technology

The invention provides a preparation method of a graphene / CoFe2O4 / polyaniline composite absorbing material. The preparation method comprises the following steps in sequence: preparing the graphene by adopting multi-walled carbon nanotubes with diameter of 30 to 50 nanometers as the raw materials; preparing the CoFe2O4 through a sol-gel auto-combustion method by adopting the Co(NO3)2.6H2O and Fe(NO3)3.9H2O as the raw materials; and then preparing the graphene / CoFe2O4 / polyaniline composite absorbing material through an in-situ polymerization method by adopting the prepared graphene, CoFe2O4 and aniline monomer as the raw materials. The composite material is higher in conductivity, magnetic performance and stability, and brings important applications in the microwave absorbing field and the electromagnetic shielding field.

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

The invention discloses an adjustable pipe hanging bracket and an adjustable hanging bracket assembly for suppressing ship pipe vibration noise, wherein the adjustable hanging bracket assembly comprises the hanging bracket. The hanging bracket comprises a base plate and an adjustment bolt, and the base plate is fixedly connected with a ship body. The hanging bracket is characterized in that the adjustment bolt comprises a bolt part on the upper portion and a spherical part at the bottom, outer threads are arranged on the bolt part, a bolt hole matched with the bolt part is formed in the base plate, the adjustment bolt is installed in the bolt hole, the spherical part of the adjustment bolt is embedded into a spherical clamping groove, an opening is formed in the top of the spherical clamping groove, the diameter or width of the opening is smaller than the diameter of the spherical part, and the bottom of the spherical clamping groove is fixedly connected to the outer wall of a pipe or the top of a pipe clamp device. The adjustable pipe hanging bracket is flexible and adjustable in connecting mode, good in vibration resistant effect and suitable for the ship pipe, meanwhile, the hanging bracket assembly based on the hanging bracket discloses a pipe clamp structure matched with the hanging bracket, and the hanging bracket assembly has the advantages of further suppressing the pipe vibration noise and being convenient to install and use.

The invention discloses a structural wave-absorbing material with an adjustable active frequency selective surface based on a PIN (positive intrinsic negative) diode. The structural wave-absorbing material comprises a plurality of wave-absorbing structure units arranged in arrays, wherein every two wave-absorbing structure units are connected by a connection line; each wave-absorbing structure unit comprises a base layer, an intermediate layer and a surface layer, the intermediate layer is attached on the base layer, the surface layer is attached on the intermediate layer, the surface layer consist of a patch type frequency selective surface and a PIN diode, the shape of the patch type frequency selective surface is a dipole pattern, and the PIN diode is welded at the center of the dipole pattern. According to the invention, the structural wave-absorbing material with adjustable wave-absorbing performance is manufactured by utilizing the PIN diode loaded with an active frequency selective surface design, a working state of the PIN diode can be dynamically adjusted, and the wave-absorbing performance of the structural wave-absorbing material can be actively adjusted; and meanwhile, the structural wave-absorbing material has the characteristics of thin thickness, light weight and large absorption frequency bandwidth.

The invention discloses a Ni-based alloy magnetic microwave absorbing material and a preparation method thereof. The stoichiometric proportions of a molecular formula of the magnetic microwave absorbing material are as follows: 16.67% of Pr, 83.33%-75% of Ni and 0-8.33% of Fe. The Ni-based alloy magnetic microwave absorbing material is prepared by the following main steps: smelting Pr, Fe and Ni metals, of which the purities are greater than or equal to 99.50% as raw materials under argon or vacuum protection; carrying out heat treatment on a cast ingot at 600-1100 DEG C under vacuum or argon protection; quenching with ice water; and grinding into powder and carrying out ball milling to form powder after mechanically crushing. The Ni-based alloy disclosed by the invention has the advantages of relatively good microwave absorbing effect, wide absorbing frequency band, simple preparation process, high antioxidant resistance and the like in a 2-18GHz of microwave band; and the Ni-based alloy magnetic microwave absorbing material disclosed by the invention is suitable for preparation of microwave absorbing products of requiring wide absorbing frequency band, good wave absorbing property and high corrosion resistance in the magnetic wave absorbing material.

The invention discloses a design method for a large-bandwidth strong-absorption metamaterial near-infrared wave-absorbing material. The method includes the following steps: 1. according to an effective medium theory and through simulation of a CST microwave studio, S parameters are obtained, wherein a frequency domain calculation mode is adopted during the simulation; periodic unit structures are periodically distributed in x and y directions and the periodic distribution is set as a periodic boundary condition; and according to parameters S11 (Omega) and S21(Omega) obtained through scanning, a resistance value is calculated. 2. through change of the period of the unit structures and the sizes of titanium resonant plates, corresponding absorption frequencies are adjusted and then the plurality of resonant plates of different sizes are horizontally placed in one unit so that absorption spectral lines corresponding to the different resonant plates are overlapped. The method adopts a high-loss metal so that a wideband wave-absorbing effect can be achieved through a simple structure. Resonant units of one size are replaced by the resonant units of different sizes so that a resonance mode of adjacent frequencies can be triggered and an absorption bandwidth can be further expanded.

The invention discloses a preparation method for an iron-doped tungsten trioxide photoelectrode. The preparation method comprises the following steps: firstly, preparing an amorphous tungsten oxide film: feeding an ITO (Indium Tin Oxide) conductive glass as a work electrode, a platinum gauze electrode as a counter electrode and a saturated calomel electrode as a reference electrode into electrolyte for electrodeposition to obtain the amorphous tungsten oxide film and drying the amorphous tungsten oxide film for later use; secondly, doping iron by using an impregnating method: feeding the amorphous tungsten oxide film obtained in the first step into 0.005mol / L Fe(NO3)3 solution and impregnating for 20-40 minutes to obtain an iron-doped tungsten oxide film, taking out the iron-doped tungsten oxide film and flushing the iron-doped tungsten oxide film with distilled water and drying the iron-doped tungsten oxide film in air; and thirdly, calcining: feeding the iron-doped tungsten trioxide photoelectrode in the second step into a muffle furnace, calcining the iron-doped tungsten trioxide photoelectrode at high temperature of 450DEG C for 3 hours, cooling the calcined iron-doped tungsten trioxide film at room temperature and then taking out to obtain the iron-doped tungsten trioxide photoelectrode. The photoelectric conversion efficiency and the photoelectric catalytic activity of the iron-doped tungsten trioxide photoelectrode are remarkably improved; the adopted experiment equipment is simple and easy to operate; and the used raw materials are abundant in natural word and low in cost and also have the advantages of environment friendliness and the like.

The invention relates to a surface mount shielding cloth electromagnetic compatibility wood-based composite material and the preparation method thereof, belonging to the field of electromagnetic compatibility material. The surface mount shielding cloth electromagnetic compatibility wood-based composite material has electromagnetic shielding function and electromagnetic wave absorption function; the surface mount shielding cloth electromagnetic compatibility wood-based composite material fulfills the electromagnetic shielding function through surface mount nickelplated or copperplated shielding cloth and the electromagnetic wave absorption function through a surface mount wave absorption plate; the wave absorption plate is prepared with silicon rubber as a basal body and the filled ferrite, carbonyl iron, graphite and silicon carbide as absorbent, and then the absorbent is stuck to the wood; the electromagnetic compatibility wood-based composite material has shield effectiveness of around 60 dB, electromagnetic wave absorbency ranges from 1 MHz to 1.5 GHz with the minimum value of -24.85 and the reflectivity of 240 MHz with the bandwidth being less than -10 dB.

The invention relates to the field of new material preparation, in particular to a light-weight broadband multilayer structural wave-absorbing composite material and a preparation method thereof. Thelight-weight broadband multilayer structural wave-absorbing composite material provided by the invention comprises three parts: a surface layer, a sandwich layer and a bottom plate. The wave-absorbingcomposite material has the characteristics of large absorption frequency bandwidth, good low-frequency performance, low surface density, high mechanical strength and the like; the bearing performanceand engineering application value of the wave-absorbing composite material are improved; and the preparation method is mature and stable, can realize large-scale continuous production, easily forms industrialization and can be applied in military and civilian fields. In the military field, the light-weight broadband multilayer structural wave-absorbing composite material is mainly used in stealthaircrafts, stealth missiles, stealth ships and the like. In the civilian field, the light-weight broadband multilayer structural wave-absorbing composite material is mainly used in high-rise buildings, medical equipment, electronic information and the like.

The invention provides an engineering electromagnetic compatibility wood-based composite material and a preparation method, belonging to the field of environmental function material. The electromagnetic compatibility wood-based composite material is the electromagnetic protection material applied to the engineering and carries out the protection on the aspects of shielding and wave absorbing; on the shielding aspect, a type of copper foil or Zn-plated iron plate covered on wood surface is adopted; on the aspect of wave absorbing, mainly aiming at the frequency range of 1MHz to 1.5GHz, single-layer interference loss is adopted, silicon rubber is taken as the substrate, MnZn ferrite is taken as main absorbent, carbonyl iron powder magnetic wave-absorbent and graphite resistance-typed absorbent are mixed, and the electromagnetic parameter of the material is adjusted: within the frequency of 1MHz to 1.5GHz, the maximum reflectivity of a wave-absorbing sheet is -12.28, and the frequency range when the reflectivity rate is less than -5dB is 965MHz. Furthermore, a dual-layer flat plate wave-absorbing material is adopted: a SiC matching layer is used on the surface layer and the MnZn ferrite and carbonyl iron powder are respectively on the bottom layer so as to be used as absorbent; the maximum reflectivity within 1-1.5GHz is -24.85dB and the bandwidth under -10dB of reflectivity is 240MHz. The engineering electromagnetic compatibility wood-based composite material leads the shielding efficiency of the composite plate to achieve 70dB and has good shielding efficiency.

The invention relates to the technical field of wave-absorbing materials, in particular to a preparation method of a silicon carbide / carbon hollow porous microsphere wave-absorbing material. The invention aims to solve the technical problems of large particle size and easy agglomeration of silicon carbide particles in the silicon carbide / carbon composite material prepared by the existing method. The method includes: mixing deionized water, anhydrous ethanol and ammonia water, adding a surfactant, resorcinol, a silicon source and a formaldehyde solution, stirring the substances uniformly at room temperature, then adding melamine, performing stirring, transferring the mixture into a high-temperature and high-pressure reactor for reaction, and conducting high temperature calcination; and thenperforming mixing with magnesium powder, conducting high temperature calcination in a nitrogen atmosphere, washing off redundant magnesium powder with hydrochloric acid, and carrying out washing anddrying. The silicon carbide / carbon hollow porous microsphere obtained by the method has good chemical homogeneity and large specific surface area, and can effectively avoid agglomeration and sinteringof silicon carbide particles. The material prepared by the method provided by the invention is used for making light and efficient wave-absorbing coatings.

The invention belongs to the field of composite material manufacturing and structure microwave-absorbing materials, and relates to a microwave-absorbing composite material with a discontinuous impedance gradient structure. A five-layer discontinuous impedance gradient structure comprising a wave-transparent layer, a low-concentration electrical loss layer, another wave-transparent layer and a high-concentration electrical loss layer and yet another wave-transparent layer is adopted; the used absorbent is electrical loss absorbent short carbon fibers; a mixed liquid is sprayed on quartz glass fiber cloth by adopting a spraying technology; and the short carbon fibers are uniformly distributed. An impedance gradient structure design is adopted by the electrical loss microwave-absorbing composite material, impedance matching can be achieved and an absorption band is effectively expanded. The short carbon fibers have the advantages of light weight, diversified loss mechanism and relatively high electromagnetic wave loss ability as an electrical loss absorbent, and the weight of the microwave-absorbing composite material is not increased. The designed and manufactured microwave-absorbing composite material has good micro-wave absorbing ability on X and KU bands.

A pyridine type metal complex having a partial structure represented by the formula (I) or (I′):wherein,M is a transition metal atom; Ds, which may be the same or different, respectively represent specific conjugated chains; Rs, which may be the same or different, respectively represent a halogen atom, a hydrogen atom, or an alkyl group having 1 to 20 carbon atoms, an alkenyl or alkynyl group having 2 to 10 carbon atoms, an aryl or heteroaryl group having 6 to 10 carbon atoms or an arylalkyl or heteroarylalkyl group having 7 to 13 carbon atoms which may have a substituent group.

The present invention discloses a porous carbon-based electromagnetic absorbing agent. The porous carbon-based electromagnetic absorbing agent comprises a plurality of dispersive two-dimensional sheetstructures, each dispersive two-dimensional sheet structure is formed by formless porous carbon frame and a graphitization carton layer inlaid into the carbon framework, and the graphitization cartonlayer is a hollow ball housing shape. The present invention further discloses a preparation method of a porous carbon-based electromagnetic absorbing agent. The porous carbon-based electromagnetic absorbing agent is high in absorption intensity in an ultra low filling degree and low thickness compared with traditional absorbing materials and metal organic framework derivative electromagnetic absorbing materials, can effectively absorb bandwidth, and has an excellent absorbing property; and moreover, the preparation method is simple in technology and low in cost, does not need complex synthesis devices, does not need usage of virulent chemical reagents and is suitable for industrial large-scale production.

The invention discloses a nanometer composite wave absorbing powder having a low density and a porous structure, and its preparation method. The preparation method of the composite wave absorbing powder comprises the following steps: 1, preparing porous ferrite through adopting a citrate sol-gel method, adding an organic additive in the porous ferrite preparation process, burning at a high temperature for combusting the organic additive to form ferrite having a porous structure; and 2, preparing an oxide doped precursor through adopting a sol-gel method, adding the ferrite having a porous structure, and burning at a high temperature to obtain the composite wave absorbing powder. The method reduces the density of the composite wave absorbing powder, the powder having a porous structure has a certain heat insulation effect, and the composite wave absorbing powder prepared through the method has the advantages of compatible absorption of radar waves and infrared waves, low density, wide absorption wave frequency band, good wave absorption performance, and simple preparation process, and overcomes the large density disadvantage of wave absorption materials prepared through using traditional ferrite.

The invention relates to a preparation method of a double-layer high-temperature-resistant heat-insulating wave-absorbing composite material, which belongs to the technical field of wave-absorbing material preparation. In the present invention, aluminum trichloride, zirconium carbonate and other materials are first prepared to obtain ceramic fiber powder, then nano-titanium dioxide and coupling agent are added to deionized water for mixing, then ceramic fiber powder is added, and after ultrasonic dispersion, heated and stirred to obtain a slurry solution, the The slurry solution and water glass are mixed, poured, molded and sintered to obtain a matrix material, and the wave-absorbing coating prepared by epoxy resin is coated on the surface of the matrix, and after curing, a double-layer high-temperature-resistant heat-insulating wave-absorbing composite material can be obtained. It is a ceramic fiber material with a porous structure, not only has high resistivity, but also has low thermal conductivity and good high temperature resistance. After being combined with the outer coating, it can quickly absorb and attenuate electromagnetic waves, with high absorption efficiency, wide frequency, light weight, Excellent mechanical properties, the coating is firmly combined with the base layer through the coupling agent, and it is not easy to fall off.

The invention discloses a LaCeNi magnetic microwave absorbing material and a preparation method thereof. The stoichiometric proportions of a molecular formula of the magnetic wave absorbing material are as follows: 10.0%-16.7% of La, 0-6.0% Ce and 83.3% Ni. The LaCeNi magnetic microwave absorbing material is prepared by the following main steps: smelting La, Ce and Ni metals, of which the purities are greater than or equal to 99.90% as raw materials under argon protection; carrying out heat treatment on a cast ingot in vacuum at 800-1050 DEG C; quenching with ice water; and carrying out ball-milling to form powder after mechanically crushing. The LaCeNi magnetic microwave absorbing material has relatively excellent microwave absorbing property in a 2-18GHz of microwave band; when the thickness of a compound is 1.5mm, the minimal absorption peak can reach about 40.1dB; the LaCeNi alloy disclosed by the invention has the advantages of good wave absorbing property, wide absorbing frequency band, simple preparation process, good corrosion resistance and the like in the 2-18GHz of microwave band; and the LaCeNi magnetic microwave absorbing material disclosed by the invention is suitable for preparation of microwave absorbing products of requiring wide absorbing frequency band, good wave absorbing property and good corrosion resistance in the magnetic wave absorbing material.

The invention discloses a middle infrared band broadband periodic?wave absorbing material based on medium regulation and pertains to the technical field of infrared?optoelectronic materials and devices. The middle infrared band broadband periodic?wave absorbing material based on medium regulation comprises a bottom-layer metal thin film and a graphical?resonant?wave absorbing?layer arranged on the bottom-layer metal thin film. The resonant?wave absorbing?layer comprises at least ten overlapped resonant layers; each resonant layer comprises a medium layer and a metal layer; and dielectric constant values of the medium-layer materials in the resonant layers are increased or decreased gradiently along the upward direction from the bottom layer. The middle infrared band broadband periodic?wave absorbing material based on medium regulation has the advantages of simple structure, controllable band, high absorbing efficiency, wide absorbing frequency?band and the like, and can be applied to a plurality of fields such as infrared camouflage, infrared?lattice imaging, infrared radiation energy?regulation and infrared optoelectronic devices.

The invention belongs to the field of building materials and particularly relates to a cement-based wave-absorbing material prepared by compounding ferroferric oxide and fly-ash hollow microspheres and a preparation method thereof. The cement-based wave-absorbing material prepared by compounding ferroferric oxide and fly-ash hollow microspheres is characterized by consisting of an absorbing layer and a matching layer, wherein the matching layer is cast on the absorbing layer, the thickness of the absorbing layer is 20-30 mm, and the thickness of the matching layer is 10-15 mm. 370 kg / <3> of cement, 13 kg / <3> of expanded perlite, 1110 kg / <3> of quartz sand, 148 kg / <3> of water and 11.1-25.9 kg / <3> of wave-absorbing agent are mixed, the surface of a sample is struck off to form the absorbing layer; according to the ratio of the expanded perlite to the cement to water of 91 kg / <3> to 944 kg / <3> to 378 kg / <3>, mixing is performed and the mixture is cast on the absorbing layer during initial setting of the absorbing layer to obtain the matching layer. The volume weight of the cement-based wave-absorbing material can be remarkably reduced, and the wave-absorbing property of the cement-based material is remarkably improved, so that the cement-based material has the advantages of having wide electromagnetic wave absorbing frequency band.

The invention discloses a noise suppression piece which comprises the following components in percentage by weight: 35-60 weight percent of flat soft magnetic alloy powder, 5-20 weight percent of a binder and 30-50 weight percent of a solvent. The invention further discloses a preparation method of the noise suppression piece. The noise suppression piece prepared by the method has the characteristics that the electromagnetic performance can be controlled, the noise suppression piece has multiple functions, the magnetic conductivity and the shielding demand can be met, the electromagnetic wave absorption effect can be improved, and the absorption band is broadened.

The invention discloses a middle-infrared band broadband cycle wave-absorbing material, and belongs to the technical field of function materials and devices. The middle-infrared band broadband cycle wave-absorbing material comprises an underlying metal film and a graphical resonance wave-absorbing layer arranged on the underlying metal film. The middle-infrared band broadband cycle wave-absorbing material is characterized in that the resonance wave-absorbing layer at least comprises two overlapped resonance layers, each resonance layer comprises a dielectric layer and a metal layer, and the dielectric constant values of the dielectric layer materials of the resonance layers are sequentially increased or decreased. According to the middle-infrared band broadband cycle wave-absorbing material, due to the fact that broadband absorption peaks of the resonance layers are overlapped, the bandwidth of the absorption peaks is extremely expanded, and more incident wave energy can be obtained from given wavebands.

The invention discloses a reduced graphene oxide / manganese ferrite (RGO / MnFe2O4) binary nano-composite wave absorbing material and a preparation method thereof. The method comprises the steps that graphene oxide, tetrahydrate manganese dichloride and iron nitrate nonahydrate serve as precursors, and by means of a one-step hydrothermal reaction, the RGO / MnFe2O4 nano-composite material is obtained,wherein the surfaces of RGO slices are loaded with cubic MnFe2O4 nano particles. The preparation method is environmentally friendly, no toxic by-product is generated, the preparation technology is simple, and the cost is low. The prepared nano-composite wave absorbing material is high in electromagnetic wave absorption capacity and wide in absorption band, by adjusting the content of MnFe2O4 in the composite material and the thickness of a coating, effective absorption of electromagnetic waves of different wavebands can be achieved, and the material has the important application value in the field of electromagnetic wave absorption and electromagnetic shielding.

The invention belongs to the field of preparation of nanometer materials and electromagnetic wave absorbing materials, the invention relates to a preparation method of a novel electromagnetic wave absorbing material, Ethanol or deionize water and Nb2AlC MAX are use as raw materials, Nb2C MXene nanosheets were synthesized by HF (hafnium) etching and hydrothermal method and their interlayer spacingand surface clusters were adjusted. At the same time, However, without adding any surfactant or template, pure Nb2C MXene was prepared by using Nb2AlC precursor, and then Nb2C MXene was modified by hydrothermal method to obtain improved Nb2C MXene nanosheets. The modified Nb2C MXene nanosheets were prepared by hydrothermal method. Nb2C MXene nanosheets have good electromagnetic wave absorption performance and wide absorption band, which can be used as microwave absorbing materials, and can be used in electromagnetic shielding technology and combat stealth technology. The process is green and environmentally friendly. The method is simple and easy to operate, easy to obtain raw materials, low production cost; The preparation efficiency is high, the quality of the prepared product is good, the stability is strong, the large-scale production can be realized, the application environment is good, and the market prospect is broad.

The invention discloses an ErFeV magnetic wave-absorbing material. The alloy comprises the following atoms in percentage: 10.5 percent of Er, 83.5-89.5 percent of Fe and 0-6 percent of V. The ErFeV magnetic wave-absorbing material is prepared by the method comprising the following main steps: taking metals Er, Fe and V with the purity of more than or equal to 99.90 percent as raw materials, smelting under argon shield, performing homogenizing thermal treatment on a cast ingot at the temperature of 600-800 DEG C in vacuum, quenching by using ice water, mechanically crushing, and ball-milling into powder. The ErFeV alloy disclosed by the invention has good wave-absorbing performance and wide absorption band in the microwave band of 2-18GHz and has the advantages of simple preparation process, abundant raw materials, low price and the like. According to the magnetic wave-absorbing material, the ErFeV magnetic wave-absorbing material disclosed by the invention is suitable for preparing microwave absorption products with wide absorption band, good wave-absorbing performance and low cost.

The invention provides a flexible stretchable electromagnetic shielding fabric and a preparation method thereof. The method for preparing the flexible stretchable electromagnetic shielding fabric comprises the following steps: selecting a spandex stretch fabric as an elastic adhesion matrix, applying a certain tension to two ends of the fabric, stretching the fabric to a certain elongation and fixing, and coating a layer of liquid elastic adhesives on the surface of the elastic adhesion matrix; performing pressure dipping on a flexible nano electromagnetic shielding composite film on the liquid elastic adhesives, coating a layer of liquid elastic adhesives on the upper side of the flexible nano electromagnetic shielding composite film, allowing the composite film to be adhered to another spandex stretch fabric, and curing the adhesives under a certain conditions; releasing the tension applied to the elastic adhesion matrix so as to drive the flexible nano electromagnetic shielding composite film to retract, thereby obtaining the flexible stretchable electromagnetic shielding fabric. The flexible stretchable electromagnetic shielding fabric disclosed by the invention has the characteristics of high elasticity, high elongation, excellent electromagnetic shield property and the like.

The invention relates to a gradient-type graphene-oxide-based structure wave absorbing material and a preparing method thereof. The method comprises the steps of utilizing a dispersing agent for preparing graphene oxide, an auxiliary, a curing agent and epoxy resin into multiple mixed sizing agents with different mass percentages of graphene oxide; conducting casting film forming on the prepared mixed sizing agents onto release paper separately through a casting method to obtain multiple graphene oxide dielectric thin films with different mass percentages of graphene oxide and in semi-solidified states; alternately splicing the obtained dielectric thin films with a hard foam material layer in sequence according to the mode of gradually increasing or gradually decreasing the mass percentages of graphene oxide to obtain a laying structure; solidifying the laying structure to obtain the gradient-type graphene-oxide-based structure wave absorbing material. The gradient-type graphene-oxide-based structure wave absorbing material has low surface density while increasing the radar wave absorbing bandwidth and absorbing depth, and hiding integration of multiple weaponry part structures canbe achieved.

The invention provides a photoelectronic device, a semiconductor substrate and a manufacturing method thereof. The semiconductor substrate comprise a silicon substrate and a metal layer positioned on the first surface of the silicon surface, wherein a plurality of grooves are formed in the first surface of the silicon substrate; and the areas among the grooves as well as the bottom surfaces and side walls of the grooves are covered with the metal layer. The grooves and the metal layer on the surfaces of the grooves can serve as U-shaped waveguides, multiple modes of surface plasma polariton excitation exist in the U-shaped waveguides, and the absorption band of the semiconductor substrate can be widened through the multiple modes of surface plasma polariton excitation, so that silicon substrate photoelectronic devices and silicon substrate photoelectric detectors are widely applied.

The invention provides a flexible stretchable electromagnetic shielding film and a preparation method thereof. The preparation method of the flexible stretchable electromagnetic shielding film comprises the following steps: selecting an elastic membrane as an elastic adhesion matrix, stretching the elastic membrane to a certain elongation, then fixing the elastic membrane, and coating a liquid elastic adhesive layer on the surface of the elastic membrane; crushing a flexible nano electromagnetic shielding complex film on the liquid elastic adhesive layer, coating resin with protective effect at the upper side of the flexible nano electromagnetic shielding complex film to form a resin layer, and curing the liquid elastic adhesive and the resin under certain conditions; and releasing a tensile force applied onto the elastic adhesion matrix, so as to drive the flexible nano electromagnetic shielding complex film to retract, namely the flexible stretchable electromagnetic shielding film is obtained. The prepared flexible stretchable electromagnetic shielding film has good elasticity, high elongation (20-50%) and excellent electromagnetic shielding property (electromagnetic wave absorptivity is more than or equal to 99% at the frequency of 1-5GHz) and can bear certain bending and compression deformation.

The invention provides a nitrogen-doped and carbon-coated magnetic nanoparticle composite microspheres and a preparation method thereof, and belongs to the technical field of materials with an electromagnetic function. According to the method, a glycerin metal complex and a nitrogenous organic compound are taken as main raw materials. A monodispersed glycerin metal complex precursor is prepared according to a self-template method at first; then the surface of the precursor is coated to form a shell by virtue of in-situ polymerization for nitrogenous organic monomers, and a carbon source and anitrogen source are introduced; and finally, calcining is carried out under an inert gas, and a core is subjected to thermal decomposition to form magnetic nanoparticles while the shell is carbonizedto form nitrogen-doped carbon. The nitrogen-doped and carbon-coated magnetic nanoparticle composite microspheres are green and environment-friendly, and efficient and time-saving in preparation process, and suitable for being prepared in a large scale; the electromagnetic parameters of the composite microspheres and the sizes of the magnetic nanoparticles can be regulated and controlled by changing the mass ratio of metal salt to the nitrogenous organic monomers, and an annealing temperature, so that impedance matching and attenuation characteristic are achieved; and the prepared composite microspheres are high in absorption intensity for electromagnetic wave, wide in effective absorption frequency band, easy to prepare in a large scale, and capable of meeting many use needs.

The invention relates to a carbon nano tube-doped poly-schiff base / carbonyl iron powder composite stealth material which is prepared by compounding a carbon nano tube, poly-schiff base and carbonyl iron powder, wherein the mass of the carbon nano tube accounts for 6-11% of the whole composite material, the mass of the poly-schiff base accounts for 27-31% of the whole composite material, and the balance of the nano carbonyl iron powder. The material has excellent microwave absorbing property, and has advantages of being wide in absorption band, low in cost, simple in preparation and low in density, thus having wide application prospect in the aspects such as microwave absorbing materials, antistatic materials, electromagnetic shielding materials and the like.