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 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 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 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 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 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 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.