31results about How to "Absorbing frequency band is wide" patented technology

The invention discloses a compounded wave-absorbing material of grapheme / four-pin zinc oxide whisker and a preparation method thereof, and belongs to the field of microwave absorption. Natural scale graphite is used as a raw material to prepare reduction-oxidation graphene; the obtained reduction-oxidation graphene is dispersed into an alcohol solution for ultrasound treatment for 3-5 h to obtain reduction-oxidation graphene dispersion liquid with the concentration of 0.3-0.6 mg / ml; adding four-pin zinc oxide whisker into the reduction-oxidation graphene dispersion liquid, wherein the mass fraction of graphene is 4-8% and the mass fraction of four-pin zinc oxide whisker is 8-12%; performing magnetic mixing for 30-40 min wherein the rotating speed is controlled at 400-600 rpm / min and the temperature is controlled within 20-40 DEG C; placing the mixed solution into a drying oven for drying, and keeping the temperature at 60-80 DEG C for 6-8 h, so as to obtain the compounded wave-absorbing material. The preparation process is simple, the prepared wave-absorbing material is excellent in wave-absorbing property, strong in wave-absorbing ability, wide in wave-absorbing frequency band, and strong in regulatory property; high absorption at different frequency can be realized by thickness adjustment.

The invention provides a strontium titanate / polypyrrole nanocomposite fiber with a one-dimensional core-shell structure, and a preparation method thereof. The nanocomposite fiber is composed of a polymer polypyrrole body and a barium strontium titanate nanofiber material, and the barium strontium titanate nanofiber is coated with the polypyrrole to form the core-shell structure. The barium strontium titanate / polypyrrole nanocomposite fiber with the core-shell structure is prepared by an electrospinning process combined gas phase polymerization technology, and the core-shell structure of the barium strontium titanate / polypyrrole nanocomposite fiber is formed by adopting barium strontium titanate as a hard template and polyvinylpyrrolidone as a soft template in the polymerization process. The one-dimensional fibrous wave absorbing material has obvious better wave absorbing ability than a spherical wave absorbing material, the shell thickness of the composite fiber is controllable, and the material of the shell has good electrical conductivity, so the expansion of the wave absorbing band of the composite material is benefited, and the composite nanofiber has the advantages of good one-dimensional morphology, uniform size distribution, good dispersion stability, and simple and easy preparation process.

The invention discloses a high-temperature-resistant wave-absorbing coating, a preparation method and application thereof. The high-temperature-resistant wave-absorbing coating is mainly composed of high-temperature-resistant wave-absorbing fillers, silica sol, nano-silica dispersion, acidic medium, glass powder, ethylene glycol, dispersant, anti-settling agent, siloxane, etc., wherein, The high temperature resistant wave-absorbing filler includes Fe 3 o 4 ‑Graphene‑SiO 2 composite nanoparticles. The high-temperature-resistant wave-absorbing coating provided by the invention can be dried naturally at room temperature, can withstand high temperatures of 100-400°C for a long time, and the formed coating has good adhesion to the substrate, high hardness, wide wave-absorbing frequency band, anti-corrosion and anti-corrosion Salt spray performance is excellent.

The invention relates to the field of wave-absorbing materials, and particularly relates to a preparation method of a carbon nano tube barium titanate heterostructure composite material. According to the method, a processed carbon nano tube forms a cladding layer on the surface by using barium titanate, and thus a good absorption effect on an electromagnetic wave is achieved. The method is simple in process and has a good absorption effect.

The invention belongs to the technical field of manufacturing radar stealth materials for military aircrafts and particularly relates to a broadband wave-absorbing force bearing composite material adopting a secondary curing process and a preparing method thereof. The material is composed of a wave-transparent foam layer, a wave-transparent skin layer, an electrical loss wave-absorbing layer and a shielding bottom layer. The wave-transparent foam layer is made of an on-sale closed-hole hard organic foam material with the thickness of 2 mm-20 mm; the wave-transparent skin layer is made of a continuous wave-transparent fiber enhancing resin matrix composite material with the thickness of 0.1 mm-4 mm; the electrical loss wave-absorbing layer is made of a wave-transparent fiber cloth enhancing composite material which contains carbon black and is 0.5 mm-5 mm thick; the shielding bottom layer is made of a carbon fiber woven cloth material. According to the broadband wave-absorbing force bearing composite material adopting the second curing process, the wave-absorbing frequency band is wider, electrical performance is stable, and the composite material can be applied to various military targets and used for manufacturing stealth structural members with high broadband stealth performance.

The invention discloses a wave-absorbing material for medical equipment, which is prepared by the following preparation methods: (1) preparation of a modifying agent, (2) modification of polyaniline, (3) preparation of an addition polymer, (4) ) Preparation of magnetic wave-absorbing active ingredients, (5) Surface treatment of magnetic wave-absorbing active ingredients, (6) Forming of wave-absorbing materials. The wave-absorbing material for medical devices prepared by the present invention overcomes the technical problems that the traditional wave-absorbing material has a limited wave-absorbing range and the wave-absorbing effect needs to be further improved, and has the advantages of high electromagnetic wave absorption frequency band and absorption rate, compatibility, mechanical properties and The advantage of better heat resistance.

The invention provides a resin wave-absorbing coating, which comprises: a composite material of resin, graphene and ferric oxide, a dispersant, an anti-sedimentation agent and a solvent. The present invention creatively changes the way of adding graphene materials in the resin wave-absorbing coating. Firstly, the graphene and the hard material in the coating—ferric oxide are compounded to obtain a composite of graphene and ferric oxide. The material is then combined with other ingredients to obtain resinous absorbing coatings. The invention can not only solve the problem of graphene dispersion well, ensure the perfect performance of its excellent performance, solve the disadvantage of uneven mixing of flexible graphene materials in the coating system, but also realize the The uniform dispersion on the surface can better exert its performance; more importantly, it can be used in conjunction with specific components, so that the prepared wave-absorbing coating has thin film, high strength, strong wave-absorbing ability, wide wave-absorbing frequency band, and low cost. low and has broad application prospects.

The invention provides a nickel oxide@lanthanum nickelate@polypyrrole wave-absorbing material in a one-dimensional double-core / shell structure and a preparation method thereof, wherein the material isprepared through electrostatic spinning with combination of liquid phase synthesis. The product has an excellent one-core / two-shell one-dimensional appearance, wherein the shell layer is composed oflanthanum nickelate and polypyrrole while the core layer is nickel oxide. The shell layer is 10-100 nm in thickness, which is controllable. The material has excellent wave-absorbing performance and wide wave-absorbing frequency band. The preparation method of the material is simple, is low in cost, is convenient and quick, and allows large scale production.

The invention relates to a wave-absorbing material with a three-layer hollow structure, a preparation method and application thereof, and belongs to the technical field of wave-absorbing materials. The three-layer hollow structure wave-absorbing material of the present invention has various loss modes such as magnetic loss, resistance loss, and dielectric loss, which makes the wave-absorbing frequency band of the particle wider and better in wave-absorbing performance. The multi-layer structure and interlayer walls in the three-layer hollow structure wave-absorbing material of the present invention improve the wave-absorbing performance of the three-layer hollow nano-particles.

The invention provides a heat-insulation stealthy high-temperature-resistant gas inlet duct. The gas inlet duct comprises a wave-transparent layer, a heat-insulation stealth layer, an electromagneticshielding layer and a low emissivity coating from inside to outside. The wave-transparent layer is formed by a continuously oxide-enhanced oxide-based composite material; the heat-insulation stealth layer is a multilayer composite material which is formed by alternately arranging heat-insulation core layers and electromagnetic periodic structure wave absorbing layers in a matching optimizing design manner, every heat-insulation core layer is a ceramic fiber mat reinforced aerogel composite heat-insulation core layer, and the electromagnetic periodic structure wave absorbing layer is composed of a high-temperature electromagnetic periodic structure cell pattern; and the electromagnetic shielding layer is formed by carbon fibers, and the low infrared emissivity coating is sprayed on the external surface of the electromagnetic shielding layer. The heat-insulation stealthy high-temperature-resistant gas inlet duct has the advantages of good heat insulation effect, wide wave absorbing frequency band, good low-frequency wave absorbing performance and certain infrared stealth performance, and can be applied to high-speed aircrafts to solve the problems of heat insulation and radar and infrared stealth of aircraft gas inlet ducts under severe aerodynamic heating conditions.

The invention discloses a microwave sintering method for a SiC ceramic roller. The microwave sintering method comprises the following steps: 1) putting a green SiC ceramic roller body in an insulation apparatus and then placing the green SiC ceramic roller body and the insulation apparatus into a microwave resonant cavity together; and 2) starting a microwave source, adjusting microwave input frequency, carrying out slow heating until humidity elimination and smoke evacuation is finished, then continuously adjusting microwave input frequency, carrying out rapid heating until reflection power is stable, carrying out heating at a heating speed of 20 to 30 DEG C / min to a sintering temperature, maintaining the temperature for 5 to 15 min, then adjusting microwave input frequency and carrying out cooling to room temperature so as to obtain the SiC ceramic roller. The microwave sintering method for the SiC ceramic roller realizes rapid sintering of the SiC ceramic roller, substantially improves uniformity and stability of the performances of a sintered material, effectively avoids the phenomenon of local surface warping of a roller at a fire hole frequently occurred during conventional sintering, improves sintering yield of the SiC ceramic roller and has the advantages of short sintering time, conservation of considerable electric energy and suitability for industrial rapid production.