13results about How to "Improve electromagnetic absorption performance" patented technology

The invention discloses a Ni3InC0.5 wave-absorbing material and a preparation method thereof, and the preparation method comprises the following steps: (1) dispersing Ni (CH3COO) 2.4 H2O and In (CH3COO) 2.6 H2O into N, N-dimethylformamide (DMF), and magnetically stirring to obtain a liquid A; (2) dispersing terephthalic acid (PTA) and triethylamine (TEA) into DMF, and magnetically stirring to obtain liquid B; (3) pouring the liquid B into the liquid A, and continuously stirring to obtain a Ni3InC0.5 precursor solution; (4) putting the solution obtained in the step (3) into a circulating water suction filter for suction filtration to obtain a gelatinous sample; and (5) taking a sample obtained in the step (4), calcining the sample in a nitrogen atmosphere, and naturally cooling the sample to room temperature to obtain Ni3InC0.5. The method has the characteristics of simple process and low cost, and the material is applied to the field of wave absorption for the first time.

The invention provides a novel resin-based silicon carbide / graphite / nickel composite wave-absorbing material and a preparation method thereof. The silicon carbide / graphite / nickel composite wave-absorbing material is prepared. The preparation method comprises the following steps: firstly, weighing graphite powder, silicon carbide powder, mullite powder and phenolic resin liquid in proportion, putting into a powder mixer in batches, uniformly mixing, taking out, drying, crushing and sieving to obtain mixed powder; secondly, preparing a graphite prototype model by using a selective laser sintering molding technology, and carrying out secondary curing to obtain a porous graphite preform; and impregnating epoxy resin liquid containing high-purity nickel powder into the porous graphite prefabricated body by using a vacuum pressure impregnation technology, and taking out the porous graphite prefabricated body for cross-linking and curing to obtain the novel resin-based silicon carbide / graphite / nickel composite wave-absorbing material. The preparation method of the resin-based silicon carbide / graphite / nickel composite wave-absorbing material is short in technological process and low in cost, controllable compounding of multiple wave-absorbing agents can be rapidly achieved, and the wave-absorbing agents are assembled into a three-dimensional micro-network structure; the method can be applied to the field of high-frequency electromagnetic wave absorption.

The invention relates to a carbon nanotube modified fiber composite material as well as a preparation method and application thereof. The preparation method comprises the following steps: cutting a fiber material and carrying out heat treatment; immersing the obtained fiber material into a chemical plating solution for heat preservation, so that the surface of the fiber is coated with a nickel-based catalyst; growing a carbon nanotube on the obtained fiber with the surface coated with the nickel-based catalyst in the presence of reaction gas to obtain the carbon nanotube modified fiber composite material. The nickel-based catalyst is firmly and completely coated on the surface of the fiber through chemical plating, so that the loading capacity and the bonding strength of the catalyst can be effectively improved; in addition, the loading capacity of the metal catalyst on the surface of the fiber can be adjusted through chemical plating, and the nickel-based catalyst can make up for the defect that the magnetic performance of the carbon nano tube is low.

The present invention relates to a nickel hydroxide modified graphene composite broadband wave absorbing material and a preparation method and application, belonging to the technical field of electromagnetic wave absorbing materials. The specific synthesis method is: pre-oxidation treatment is performed on the graphene raw material using hydrogen peroxide. This step creates a large number of defects on the graphene surface to create conditions for the loading of nanoparticles. Then, nickel hydroxide is loaded on the pre-treated graphene surface under the condition of different alkaline solution addition amounts. The nickel hydroxide particles under different synthesis conditions have different sizes. By adjusting the loading conditions, the modification effect of nickel hydroxide on graphene can be optimized, and the overall absorption capacity of electromagnetic waves is enhanced, thereby obtaining a broadband electromagnetic absorption material. At the same time, the synthesis process of the material is simple, the filling ratio and application thickness are low, and it can meet the needs of industrial production and has application value.

Provided is a thermoplastic resin composition capable of obtaining uniform electromagnetic absorption performance with no in-plane variation in a molded article thereof as a result of the fluidity being favorable in addition to the reflection loss and transmission loss being high. A thermoplastic resin composition according to the present disclosure which is to be used in an electromagnetic wave absorber and contains a thermoplastic resin (A) and carbon nanotubes (B), wherein the carbon nanotubes (B) satisfy formulas (1) and (2), and a sheet having a thickness of 100µm and formed from the thermoplastic resin composition has a sheet surface maximum height Sz of 5µm or less when measured according to ISO 25178. (1) The full width at half maximum of the diffraction peak of the (002) plane in powder X-ray diffraction analysis is 2.0-6.0°. (2) The ratio (G / D) of the maximum peak intensity G in a 1,560-1,600 cm-1 range in a Raman spectrum to the maximum peak intensity D in a 1,310-1,350 cm-1 range therein is 0.5-2.0.

This invention belongs to the field of electromagnetic wave absorbing materials technology, specifically relating to an absorbing material, its preparation method, and its application. This invention uses multi-walled carbon nanotubes (MWCNTs), potassium permanganate (KMnO4), and divalent manganese as raw materials, based on Mn... 2+ With MnO4 ‑ The redox reaction between the two components allows for in-situ uniform loading of MnO2 nanoparticles onto the MWCNT surface through simple stirring in a room-temperature liquid environment, resulting in microwave absorption performance superior to most similar absorbing materials. Compared to traditional methods for preparing absorbing materials, the technical route of this invention offers significant advantages, including simple preparation process, no pollutant emissions, energy-saving and environmentally friendly process, adjustable and controllable material structure, excellent microwave absorption performance, and scalability. This method effectively overcomes the technical limitations in the preparation of absorbing materials, providing a scalable new paradigm for the green and large-scale production of high-performance absorbing materials.

The present invention relates to the technical field of carbon fiber materials and composite materials preparation thereof, specifically a biomass-based silicon carbide composite fiber and a preparation method thereof and an electromagnetic absorption material. The present invention provides a biomass-based silicon carbide composite fiber, comprising a hollow carbon fiber and silicon carbide composited in the hollow carbon fiber; the hollow carbon fiber is a carbide of tree cotton fiber. The composite fiber provided by the present invention selects tree cotton fiber with a hollow morphology, high hollowness and large specific surface area as a raw material, and the hollow carbon fiber obtained after carbonization treatment is used as a carbon source to carry out a carbon thermal reduction reaction to introduce a silicon carbide phase to realize a carbon / silicon carbide composite fiber. Under the action of a catalyst, the silicon carbide component can shuttle inside the hollow carbon tube, increase the interface of the composite material and adjust its dielectric constant, so as to optimize the electromagnetic absorption performance; it can realize the application in the electrochemical direction, improve the economic added value of the tree cotton fiber and show multifunctional application.

This invention discloses a cobalt-based Hassler alloy material, its preparation method, and its application. The preparation method includes the following steps: (1) Weighing cobalt powder, iron powder, and germanium powder in a molar ratio of 2:(1~1.75):(0.25~1), mixing them, placing them in a tungsten carbide grinding jar, adding anhydrous ethanol, adding grinding balls, and ball milling; (2) Drying and sieving the ball-milled powder, taking the sieved magnetic alloy powder, sealing it in a vacuum quartz tube, heat-treating it using a muffle furnace, and cooling it to room temperature with the furnace to obtain a cobalt-iron-germanium Hassler alloy. This invention uses a ball milling method, which can effectively change the surface morphology of the alloy powder, making it form a flake powder with a larger specific surface area, thereby improving the electromagnetic absorption performance of the magnetic alloy; by selecting and changing the proportion of the Hassler alloy components, the saturation magnetization of the magnetic alloy can be effectively increased, its Curie temperature can be increased, and the electromagnetic wave absorption performance of the magnetic alloy at high temperatures can be improved.

This invention relates to the field of functional composite materials technology, and particularly to a high-frequency absorbing multilayer woven fabric and its preparation method. An embodiment of this invention provides a high-frequency absorbing multilayer woven fabric, which, along its thickness direction, sequentially comprises a frequency selective layer, a dielectric modulating layer, and a penetration blocking layer; the frequency selective layer comprises multiple periodically arranged periodic patterns obtained from conductor fabrication for absorbing the Ka-band. This invention provides a high-frequency absorbing multilayer woven fabric and its preparation method, which not only maintains good electromagnetic absorption in the 26-40 GHz high-frequency range, but also possesses the flexibility and durability of a fabric.

The application discloses a preparation method of carbon-based wave-absorbing coating powder for plasma spraying, a product and application thereof, and belongs to the technical field of functional materials. Lithium-aluminum-silicon gel powder, graphene oxide and N precursor are added into water and uniformly mixed, the obtained slurry is dried, and heat treatment is carried out in an inert atmosphere to obtain ceramic / graphene wave-absorbing powder; sodium silicate aqueous solution is added into the ceramic / graphene wave-absorbing powder, and stirring is uniformly carried out to obtain a wet mixed solid, and high-speed shearing is carried out to obtain a solid powder; the above operation is repeated, the finally obtained sample is dried and subjected to secondary heat treatment to obtain the carbon-based wave-absorbing coating powder for plasma spraying. Through a liquid sodium silicate foaming method, the outer layer of the ceramic / graphene wave-absorbing powder is coated with sodium silicate, the high-temperature resistance and oxidation resistance of the powder are improved, and the plasma spraying and the wave-absorbing coating are combined together, so that the application range of the coating is widened.

The application is a honeycomb concrete wave-absorbing structure based on a full-dielectric phase gradient metasurface, which is composed of a base fiber honeycomb concrete and a top full-dielectric phase gradient metasurface structure. The base fiber honeycomb concrete is divided into a multi-layer structure by different contents of wave-absorbing agents, the impedance matching is adjusted by changing the content and type of the wave-absorbing agents, and the function of maximum absorption of electromagnetic waves is achieved. The fiber wave-absorbing honeycomb woven by wave-absorbing fibers enables the concrete to have good toughness and strength, and achieves the dual effect of synergistic enhancement of wave-absorbing and mechanical properties. The size and shape of the micro units in the full-dielectric phase gradient metasurface can be flexibly adjusted, different micro units are combined, electromagnetic waves produce different phases, and the purpose of flexibly adjusting the electromagnetic wave-absorbing performance of different frequency bands is achieved. Through the combination of 3D fiber honeycomb structure, multi-layer wave-absorbing structure and metasurface and other factors, the optimal electromagnetic wave-absorbing structure is prepared, and the requirements of thin, light, wide and strong of the electromagnetic wave-absorbing material are met.

The present invention discloses a broadband three-dimensional dendritic absorbing material and a preparation method and application thereof. The three-dimensional dendritic absorbing material prepared by the present invention uses a Co-based MOF with a dendritic structure as a precursor, and after calcining at different temperatures under nitrogen, a Co / C composite material with a three-dimensional dendritic structure is obtained. Due to the unique structure and multiple loss mechanisms, an effective absorption bandwidth of 7 GHz is obtained under four temperature conditions, and after calcination at 550°C, a reflection loss of ‑51.2 dB is obtained when the thickness is 2.5 mm, and an ultra-wide effective absorption bandwidth of 7.92 GHz is obtained. Therefore, the synergistic effect of the structural design of the material and the loss mechanism is of great significance for optimizing the performance of the absorbing material and broadening the effective absorption bandwidth.

The invention discloses an implantable ultrasonic stimulation device and method based on electromagnetic sound, which can realize a novel transcranial ultrasonic stimulation technology by organically integrating an electromagnetic sound principle and an implantable and controllable high electromagnetic absorption material. The device comprises an electromagnetic wave generation module, a magnetic field generation module, an ultrasonic wave generation module, an ultrasonic signal acquisition module and an image processing and analyzing module. According to the device and the method, the high electromagnetic absorption material implanted into the cranium is excited by using electromagnetic waves to generate ultrasonic waves, so that stimulation on brain tissues in different areas and at different depths is realized, and the stimulation intensity can be adjusted. Compared with traditional transcranial ultrasonic stimulation and transcranial direct current stimulation technologies, the transcranial direct current stimulation system has the advantages of being efficient in stimulation, adjustable in stimulation position, capable of positioning a sound source in real time, adjustable in strength, deep in penetration, capable of achieving long-term stimulation, biocompatible, low in cost and the like, and has large potential application value in the fields of cranial nerve regulation and control, brain medicine precise delivery and the like.