7results about How to "Excellent electromagnetic wave absorption performance" patented technology

The application discloses a kind of natural rubber filling nickel-aluminum bimetallic hydroxide multi-walled carbon nanotube composite material for electronic component packaging, belong to packaging material technical field, the composite material includes natural rubber matrix and dispersed nickel-aluminum bimetallic hydroxide / multi-walled carbon nanotube hybrid filler, the hybrid filler is made of multi-walled carbon nanotube and nickel-aluminum layered double hydroxide grown in its surface in situ.Its preparation method is: multi-walled carbon nanotube, nickel source, aluminum source, urea and ammonium fluoride are dissolved in water and prepared hybrid filler by hydrothermal reaction;Then it is mixed with natural latex, vulcanization aid dispersion, freeze-drying, vulcanization is obtained.The application improves the dispersibility of filler by constructing LDH / MWCNT hybrid structure, uses phonon transmission optimization, synergism of loss and impedance, combustion inhibition and the friction and reinforcing mechanism of hybrid filler and natural rubber molecular chain, so that the thermal conductivity, electromagnetic wave absorption capacity, flame retardancy, mechanics and damping performance of the composite material are simultaneously improved, suitable for electronic component packaging field.

This invention belongs to the field of electromagnetic wave absorbing materials technology, and specifically discloses a hollow spherical Ti3C2T x @Molybdenum disulfide@cobalt / carbon composite materials, their preparation methods, and applications. The preparation method includes the following steps: reacting formaldehyde with melamine to prepare melamine-formaldehyde resin particles, ultrasonically dispersing them in water, and then adding Ti3C2T. x Suspension, stirred, melamine-formaldehyde resin particles with Ti3C2T x Self-assembly yields the core-shell material Ti3C2T x @MF; Ti3C2T x @MF, molybdenum source, and sulfur source are dispersed in water in a certain proportion and subjected to a hydrothermal reaction. The hydrothermal reaction product is washed and dried to obtain hollow spherical Ti3C2T x @Molybdenum disulfide composite material HTM; A dimethylimidazole alcohol solution is slowly added to a mixed alcohol solution of HTM and a cobalt source, stirred for a set time, and then allowed to stand for a set time to obtain HTM@ZIF67; HTM@ZIF67 is then pyrolyzed in an inert atmosphere to obtain hollow spherical Ti3C2T. x @Molybdenum disulfide@cobalt / carbon composite material. This material combination can effectively promote the attenuation of electromagnetic waves and reduce the material's filler content.

This invention discloses an electromagnetic wave absorbing material based on in-situ grown carbon nanotubes from FeCoNi alloy and its preparation method. First, an iron-based metal-organic framework is synthesized via a hydrothermal reaction, followed by ultrasonication, washing, and drying to obtain iron-based metal-organic framework nanoparticles. Then, the surface of the iron-based metal-organic framework nanoparticles is modified using polyvinylpyrrolidone, and Co is adsorbed onto them. 2+ and Ni 2+ Polyvinylpyrrolidone (MOF)-modified iron-cobalt-nickel (FeCoNi)-based metal-organic framework (MOF) nanoparticles were obtained. Finally, melamine and the cobalt-nickel-adsorbed MOF-modified FeCoNi-based MOF nanoparticles were subjected to a carbothermal reduction reaction under a nitrogen atmosphere to obtain the electromagnetic wave absorbing material. This invention relies on MOF porous templates and metal nanoparticles to catalyze the growth of carbon nanotubes, improving conductivity loss. Simultaneously, the interfacial polarization between the generated FeCoNi nanoparticles and the carbon matrix optimizes impedance matching and enhances electromagnetic wave absorption performance.

This invention belongs to the field of microwave absorbing materials technology, specifically relating to a carbon composite microwave absorbing material and its preparation method. The invention uses degummed waste filter cotton as a carbon source, employing an impregnation method to impregnate the pretreated waste filter cotton in magnetic metal salts, followed by heat treatment to obtain the composite microwave absorbing material. The carbon skeleton formed by the heat-treated waste filter cotton constitutes a conductive network in the composite material, exhibiting good dielectric loss. Magnetic metal elements and their alloys possess high saturation magnetization, providing magnetic loss in the composite material. The synergistic effect of dielectric and magnetic losses solves the problem of poor impedance matching in single carbon materials. The preparation process of this invention is simple and pollution-free, solving the environmental pollution problems caused by traditional waste filter cotton treatment methods, and is easy for large-scale production. The resulting composite microwave absorbing material is lightweight, efficient, has good impedance matching, and possesses excellent microwave absorption performance.

This invention discloses a high-entropy spinel ceramic powder, its preparation method, and its applications. The high-entropy spinel ceramic powder of this invention has the chemical formula MFe₂O₄, where M is composed of at least 11 elements selected from Ba, Ca, Sr, Mg, Ti, Co, Ni, Fe, Cr, Mn, Cu, Zn, Mo, Al, and W. The preparation method of the high-entropy spinel ceramic powder of this invention includes the following steps: mixing metal oxide powder and Fe₂O₃ powder, wet ball milling, drying, and grinding; then adding the mixture to a graphite crucible and compacting it; followed by laser radiation heating to obtain the high-entropy spinel ceramic powder. The high-entropy spinel ceramic powder of this invention possesses excellent and stable microwave absorption properties and a high service temperature, making it suitable for use in stealth coatings for aerospace vehicles. Furthermore, its preparation method is simple and rapid, with a large potential for component synthesis, making it suitable for large-scale industrial production and application.

This invention belongs to the field of electromagnetic wave absorbing materials technology, specifically relating to a nickel-boron-doped cobalt-based layered carbon absorbing material and its preparation method. This invention utilizes a cobalt-based boron imidazole precursor framework as a template, and forms a two-dimensional layered layered double hydroxide (LDH) through a chemical oxidation etching process using nickel ions. This LDH is then subjected to high-temperature reduction to obtain the nickel-boron-doped cobalt-based layered carbon material. This material leverages the unique properties of two-dimensional materials to achieve high impedance matching, allowing electromagnetic waves to enter the absorber at a significant rate. Furthermore, the material's excellent dielectric polarization and magnetic coupling attenuate the electromagnetic waves entering the absorber. The material achieves a minimum reflection loss of -60.1 dB and a maximum effective absorption bandwidth of 6.24 GHz, giving it excellent electromagnetic wave absorption capabilities. The preparation method of this invention is simple and easy to mass-produce.

This invention discloses a method for preparing a core-shell structured TiO2@N / C@Co / C composite microwave absorber. Specifically, the method involves: preparing MIL-125-NH2 powder using a microwave-assisted synthesis method; preparing MIL-125-NH2@ZIF-8 powder using an ultrasonic synthesis method; mixing the MIL-125-NH2@ZIF-8 powder with Co(NO3)2·6H2O, adding methanol for ultrasonic dispersion and stirring, and then carbonizing the resulting MIL-125-NH2@ZIF-8@ZIF-67 powder. This invention effectively improves the impedance matching of the microwave absorber by introducing a multi-component MOF, allowing incident electromagnetic waves to enter the composite absorber for dissipation and attenuation. Furthermore, the abundant heterogeneous interfaces in the core-shell structure can induce interfacial polarization losses, thereby increasing the absorption of electromagnetic waves.