Nano absorber material refers to the material whose characteristic size of the material component is on the order of nanometers (1~100nm). The material is composed of "particle component" and "interface component". In recent years, the development of nanomaterials has provided new possibilities for absorbing materials. Nanomaterials have a large proportion of interface components due to their small particles. The size effect and interface effect have an important impact on the properties of the material. Its unique structure and many peculiar properties are manifested in mechanics, optics, magnetism, heat and chemistry. The extremely high electromagnetic wave absorption performance of nanomaterials has attracted widespread attention. Nanomaterials have good wave absorption. At the same time of function, it has the characteristics of good broadband compatibility, light weight and thin thickness. Britain, the United States and other countries have included it in the new generation of stealth materials for research. Under the radiation of the microwave field, the movement of atoms and electrons in the nanomaterials is intensified, which promotes magnetization and converts electromagnetic energy into heat energy, thereby increasing the absorption performance of electromagnetic waves. For nanocomposite materials in visible light and other wavelength bands, a single absorption particle matching design mechanism is proposed, which can give full play to the role of the unit mass loss layer.
(1) Nano metal and alloy wave absorbing agent
It is mainly a composite powder of nano metal and nano alloy, mainly Fe, Co, Ni and other nano metal and nano alloy powder. It adopts a multi-phase composite method, and its absorbing performance is better than single-phase nano metal powder. The bandwidth with a rate greater than 10dB can reach 3.2GHz, and the absorption rate at the resonant frequency point is greater than 20dB. The proportion of each component in the composite, the particle size, and the microstructure of the alloy powder are the main factors affecting its absorbing performance.
(2) Nano metal oxide magnetic ultrafine powder wave absorbing agent
This type of absorbent has two types of single oxide and composite oxide. The former mainly includes Fe2O3, Fe3O4ZnO, Co3O4, TiO2, NiO, MoO2, WO3 and other nano magnetic ultrafine powders; the latter mainly includes LeFe3, L. a SrFe(3 Nano-magnetic ultra-fine powders. These metal oxide (and some non-metallic materials) nano-ultra-fine powders have more and more atoms on the surface during the refining process, which enhances the activity of nano-materials.
(3) Nano silicon carbide absorbent
Silicon carbide ceramic material has good mechanical properties and thermal physical properties, especially its high temperature resistance, high strength, corrosion resistance, low relative density, high resistivity, and its good wave absorbing performance, which can weaken the infrared signal of the engine. One of the wave absorbers with wide application and rapid development. The absorbing material prepared by the absorbing agent has stable electromagnetic performance at high temperature, and is especially suitable for engines with working temperature up to 1000°C. The absorption band of nano-silicon carbide is wider, and it has a good absorption effect on the millimeter wave band and the centimeter wave band. After nano-silicon carbide and magnetic nano-wave absorbing agent (such as nano metal powder, etc.) are combined, the absorbing effect can be greatly improved. There is also a great improvement.
(4) Nano graphite wave absorbing agent
Nano graphite is often used in combination with absorbents such as nano silicon carbide. Nanographite as a wave absorber can be used to make graphite thermoplastic composites and graphite epoxy composites, these materials still maintain toughness at low temperatures.
(5) Nano Si/C/N and Si/C/N/O absorbers
The main components of nano-SiC/N wave absorbers are silicon carbide, silicon nitride and free carbon, which mainly rely on silicon carbide and free carbon to absorb and attenuate radar waves, and the content of silicon nitride to adjust the overall resistivity. The main components of nano SiC/N/O absorbent are SiC, Si3N4, Si2N2O, SiO2 and free carbon. Recent studies have shown that SiC/N and Si/C/N/O nano-wave absorbing agents have strong absorbing properties not only in the centimeter wave band, but also in the millimeter wave band.
(6) Nano conductive polymer wave absorber
Conductive polymers have diversified structures, low density, unique physical and chemical properties, and their electrical conductivity can vary within the range of insulators, semiconductors and metal conductors. Among them, polyacetylene, polypyrrole, polythiophene and polyaniline are High polymer with conductive structure. These conductive polymer nano-powders have very good absorbing properties. It has a better absorbing effect after being combined with nano-metal absorbing agents/combined with inorganic magnetic loss substances or ultrafine particles to produce new lightweight broadband microwave absorbing materials .
(7) Nano metal insulating dielectric film absorber
This is a wave absorbing agent made of metal deposited on an insulating dielectric film, and the thickness of the metal film and the insulating dielectric film are maintained at the nanometer level. France has recently successfully developed a broadband microwave absorbing coating, which is composed of an adhesive and nano-scale microchip filling materials.
(8) Nano metal film/insulating dielectric wave absorbing agent
This kind of absorber deposits a nano-scale metal film on an insulating dielectric sphere, that is, a multi-layer nanoparticle film absorber is generated on the surface of the hollow glass sphere by sputtering film formation technology.
(9) Nano-nitride wave absorbing agent
Nano-nitride wave absorbers mainly include silicon nitride and iron nitride. Nano-silicon nitride has a relatively large dielectric loss at 102~106Hz. Nano-iron nitride has a high saturation magnetic induction intensity and a high saturation magnetic current density, and may become a nano radar wave absorber with excellent performance. Nano radar wave absorbers, as a new type of absorber, are still in the development stage. However, they have great potential and there may be greater breakthroughs. In response to the higher requirements of "thin, light, wide, strong" properties of absorbing materials, magnetic nanoparticles, nanoparticle films and multilayer films will become a new generation of practical wave receivers.