4results about How to "Absorption Bandwidth" patented technology

The application discloses a carbon-composite high-entropy metal oxide electromagnetic functional material and a preparation method thereof, and relates to the technical field of microwave absorbing materials. The electromagnetic functional material is composed of (Fe 0.2 Co 0.2 Ni 0.2 Mn 0.2 Cr 0.2 )3O4 / C, and the preparation method comprises the following steps: adding equimolar iron salt, cobalt salt, manganese salt, chromium salt and nickel salt into water together with urea, polyvinylpyrrolidone and a carbon source to configure a mixed solution, then heating and reacting, centrifuging and drying the reaction product after the reaction is completed, and obtaining the electromagnetic functional material. By introducing the carbon material with high dielectric constant, the electric conduction performance and the electric loss performance are enhanced, the impedance matching is optimized, the overall density is reduced, the absorption bandwidth is widened, the effective absorption bandwidth covers the full wave band of 2-18GHz, the electromagnetic functional material is suitable for multi-wave bands, and the problems of low absorption rate and narrow frequency band are solved. Moreover, the preparation process is simple, and the one-time hydrothermal reaction can be completed, so that the scale production is facilitated.

The application provides a magnetic metal powder / porous carbon composite material, a preparation method and application thereof. The preparation method comprises the following steps: step S1, performing surface oxidation reaction on a magnetic carbonyl metal powder to form pretreated metal powder; step S2, dissolving a copolymer PS n -b-PEO m in a first solvent, adding a mixed solution of ethanol and water into the first solvent to obtain a milk emulsion; step S3, adding the pretreated metal powder, pyrrole and FeCl3 into the milk emulsion to perform in-situ polymerization reaction, so as to form a precursor and obtain a precursor solution; step S4, removing the spherical PS n -b-PEO m micelles in the precursor by a solvothermal method, and then drying to obtain a porous precursor; and step S5, calcining the porous precursor under an inert atmosphere to obtain the magnetic metal powder / porous carbon composite material. The magnetic metal powder / porous carbon composite material prepared by the application has better wave absorption performance in a low frequency band.

The invention discloses a NiCo-MOF derived carbon nanotube wave-absorbing material with a core-shell structure and a preparation method of the NiCo-MOF derived carbon nanotube wave-absorbing material, and relates to the technical field of wave-absorbing materials. According to the method, NiCo-MOF with a core-shell structure is obtained by controlling the solvent proportion, then a carbon nano tube grows on the surface of the NiCo-MOF in situ, the prepared MOF-derived carbon nano tube has a hollow core-shell structure, and the surface of the MOF-derived carbon nano tube is covered with a layer of dense carbon nano tube. By adopting the structure, the conductivity of the material is greatly improved, the types of interface polarization are enriched, and good wave absorbing performance is shown in the frequency band of 2-18 GHz; the hollow structure is beneficial to multiple reflection of electromagnetic waves inside, and when the matching thickness is 2.5 mm, the effective absorption bandwidth can reach 5.7 GHz, and the minimum absorption peak reaches 4.8 GHz. The method is simple in technological process, low in cost and suitable for large-scale preparation, and has wide application prospects in the fields of light broadband wave absorption, thermal protection and the like.

This invention belongs to the field of coloring pigments and their preparation technology, specifically relating to an ion-absorbing silicate coloring pigment. The general formula of its initial raw materials is: x AX 1 / δ · m MX 2 / δ · n SiX 4 / δ · y REX 2或3 / δ A carbon source is added, and the mixture is calcined at 900-1500℃ in an inert or reducing atmosphere for 1-50 h to obtain an ion-absorbing silicate coloring pigment. The resulting pigment can achieve continuous coloring in the blue-green to red-orange visible light region under sunlight. This ion-absorbing silicate inorganic coloring pigment is non-toxic, exhibits strong absorption in the blue-green light region with a wide absorption band, and overcomes the shortcomings of the aforementioned functional luminescent pigments, such as weak light absorption, extremely poor coloring performance, and unstable coloring. It also possesses many advantages that make it an ideal coloring pigment, including abundant and inexpensive raw materials, stable physicochemical properties, simple synthesis conditions, good compatibility with glass and ceramics, and environmental friendliness during preparation and use.