Classification and application of stealth coatings

China Coatings network
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the afternoon of December 19, 2014, the latest number 2015 domestic fourth-generation fighter J-20 successful flight. This is less than a month away from the success of the first flight of the J-20 in 2013. It is reported that China has now exposed 6 J-20s, and in 2014 a year, from 2011 to 2015 (2014 has not yet been publicly unveiled), 4 J-20 successful first flight, indicating that the J-20 project is progressing smoothly, and the emergence of the 2015 J-20 will further accelerate the pace of J-20 service. At the same time, with china's J-20 becoming the United States F-22, Russia's T-50 after another stealth fighter family members, stealth
coal
has also become a topic of much interest.
incognito is not the "incognito" of sci-fi, but a combination of techniques and techniques in military terminology that refer to controlling the observability of a target or controlling the signals of the target's characteristics. With the development of science and technology, stealth technology is widely used. Stealth technology is designed to reduce the radar, infrared, photoelectrical, visual and other observation characteristics of aircraft in the design of specialized technology, the use of stealth technology is for the aircraft in the sudden defense is not easy to be detected by enemy detectors, thereby enhancing the suddenness of the attack, improve the viability and combat effectiveness of the aircraft.
, the most challenging stealth technology is the development and application of stealth coatings. Stealth coating as one of the most convenient, economical, highly adaptable stealth technology has been widely used in aerospace, military equipment. In recent years, the United States, Britain, Russia, France and other military powers have invested heavily to increase the development of stealth paint. Obviously, the development of stealth coating not only marks the progress of a country's scientific field, but also relates to the consolidation of national defense forces, there is a huge space for survival and development at this stage.
Stealth Coatings are stealth materials fixed to the structure of weapon systems, which can be divided into radar stealth coatings, infrared stealth coatings, visible invisible coatings, laser stealth coatings, sonar stealth coatings and multi-functional stealth coatings. Stealth coating requires chemical stability at a wide temperature; Better band characteristics; The surface density is small and the weight is light. High bonding strength, resistant to certain temperatures and different environmental changes.
electromagnetic waves emitted by radar stealth coatings
radars are easily induced to generate the same frequency electromagnetic currents and establish electromagnetic fields to radiate energy to radar secondary when they touch metal materials. The research of radar stealth technology mainly focuses on structural design and absorbent material. In material stealth design, there are two key problems: First, how to make the incoming wave can enter the inside of the material without being reflected by the surface; The second is how to allow the electromagnetic waves entering the inside of the material to be absorbed and decayed quickly by the material. Radar stealth coating should minimize the possibility of radar survey. At present, there are many absorbent coatings used in various weapons and equipments, and here are a few brief introductions.
Ferride absorbent coatings
including nickel-zinc ferride, manganese zinc ferride, lithium zinc ferride, lithium-titanium ferride and ferronic ferride, etc., are the earliest and most widely used coating varieties. Because of the frequency dispersion efficiency of strong ferrical resonance absorption and magnetic conductivity, ferronic oxygen absorption material has the characteristics of strong absorption and frequency bandwidth, and is widely used in stealth fields, such as the SR-1 high-altitude reconnaissance aircraft in the United States on the use of ferronic absorption coating. In recent years, the ferrite body studied mainly includes hexagonal crystal ferrite and sharpstone ferrite.
-based iron absorbent coating
niobium-based iron absorbent coating is a typical magnetic loss-type absorbent coating, with strong absorption capacity, easy to apply and so on. However, due to the high density of ferring absorbers, the volume-to-empty ratio in coatings is generally greater than 40%, so the resulting wave-absorbing coating still has the disadvantage of large surface density. Corrosion-resistant polycrystalline iron fiber absorbent coatings have been used on F/A-18E/F and A/F-117X aircraft.
ceramic absorbent coating
these absorbents have lower density than ferride, composite metal powder and other absorbents, good absorption performance, can effectively reduce infrared radiation signal characteristics. Among them, silicon carbide is the main component of making multi-band absorbent coating, it is possible to achieve light, thin layer, broadband band and multi-band, very promising application.
Ultra-fine metal powder absorbent coating
fine metal ultra-fine powder can make it make up the number of particles of atoms greatly reduced, magnetic, electrical, optical and other physical properties of qualitative changes, magnetic loss is greater. The absorbent coating made with this absorbent can adjust the electromagnetic parameters of the absorbent coating by adjusting the particle size, content and mixing ratio of the powder, so as to achieve the ideal absorbent effect.
nomeometer absorbent coating
Nanomaterials, as one of the key technologies of stealth technology, are easy to achieve high absorption, thin coating, light weight, absorption bandwidth, infrared microwave absorption compatibility and other requirements, is a promising high-performance, multi-functional materials. It is reported that the "ultra-black powder" nano-absorbent material developed by the United States has a 99% absorption rate of radar waves; The wide-band microwave absorbent coating material developed in the United States is composed of adhesive and nano-scale micro-powder fillers% of these multi-layer structures have good magnetic conductivity and infrared radiation rate, and have good absorption performance for electromagnetic waves from 50MHz to 50GHz.
nanomaterials are the ideal black body in physics, nano-zinc oxide powder, niobium-based iron powder, nickel powder, ferrica powder and iron, nickel alloy powder, etc. are excellent electromagnetic wave absorption materials, not only can absorb radar waves, but also can absorb visible light and infrared light, with this preparation of absorbent paint and structural wave-absorbing materials, can significantly improve the aircraft, tanks, ships, missiles, torpedoes and other weapons and equipment stealth properties, will be the inevitable trend of future development.
Plasma absorbent coating
plasma absorbent coating is to apply radioactive material to the target, so that the target surface near the local space ionize, the formation of plasma to absorb the energy of electromagnetic waves. The biggest feature of this technology is that it does not have to change the structure of the equipment, only the plasma generator can be used for stealth purposes, and stealth effect is very good. At present, the more advanced countries of this technology are Russia and the United States.
infrared stealth coating
infrared stealth coating process is simple, easy to build, durable, low cost, is currently the most important varieties of stealth coatings. It is mainly aimed at the detection of infrared cameras, designed to reduce the brightness of aircraft in the infrared band, disguise or deform the shape of equipment in infrared cameras, reduce the probability of its detection and identification. The key to infrared stealth lies in the target's ability to form thermal camouflage in different regions using the difference in radiation brightness, and the key to its development is to find resin adhesive with low emission rate. Rubber butyl rubber, polyethylene and ethylene acetate co-polymers with ring structure have better infrared transparency and can be used as adhesive for infrared coatings.
Visible light stealth coating
visible light stealth coating, also known as video stealth technology, it is for human vision, 2, video and other means of observation to take stealth technology, the purpose is to reduce the target characteristics of the aircraft itself, less target and background between the brightness, color and motion of the contrast features, to achieve the target visual signal control, in order to reduce the probability of visible light detection system to find the target. Visible light stealth paint usually uses camouflage methods to make aircraft invisible, such as protection camouflage, imitation camouflage, deformation camouflage. A kind of visible light stealth is camouflage barrier, which simulates the electromagnetic radiation characteristics of the background, so that the target can be obscured and fused with the background, is the most important means of fixed target and motion target stay, and camouflage coating is an important component of this technology application. All in all, visible light stealth coatings are widely used, easy to use, economical, aircraft stealth coatings in the development of more mature technology.
multi-spectrum stealth coatings
this kind of coating generally refers to visible light, infrared and radar compatible stealth coatings, with advanced infrared detectors, mi-wave radar, millimeter-wave radar, lidar and other advanced detection equipment has come out, stealth materials are moving towards compatible with rice wave, cm-wave, infrared, laser and other multi-band electromagnetic wave stealth multi-spectrum direction. In recent years, foreign advanced multi-functional stealth materials in visible light, far infrared, 8mm and 3mm five-band integration has made some progress.
Laser stealth paint
laser-guided missiles or bombs throwing accuracy, combat capability has reached an alarming level, so that can be found to be hit, hit will be destroyed, seriously threatening the survival of ground weapons, therefore, modern battlefield ground weapons laser stealth is essential.
The principle of laser stealth is mainly based on the range-measuring equation of laser rangefle machine, in order to realize laser stealth and weaken the range-measuring ability of laser rangefle machine to shorten its maximum range, it is necessary to reduce the reflectivity of the target to the laser. At present, the detection frequency of commonly used laser detectors is mainly concentrated in the two frequency bands of 1.06 m and 10.6 m. Laser stealth coating in this band has a high molar absorption rate, its chemical stability, thermal stability and aesthetic performance and other comprehensive performance is excellent, so its application range is very wide.
from the current situation of the development of stealth technology at home and abroad, "thin, wide, light, strong" is the direction of the development of stealth technology. Therefore, the development and development of broadband compatibility, low-cost, multi-functional nano-stealth coating is an inevitable trend. First, the struggle of military reconnaissance increasingly requires better performance of stealth materials, and secondly, the development of nano-technology for nano-stealth coatings to provide a technical basis and material reserves, these two factors will promote the development of nano-stealth coatings to a higher level. With the increasing attention of countries to stealth technology, the research on nano stealth coatings will be more in-depth, a large number of military equipment applications of nano stealth coatings will be possible.