Application of Conductive Polymer Materials in Stealth Technology

(1.Department of Chemical Engineering, Northwestern Polytechnical University, Xi'an 710072, China. The Military Representative Office of the Air Force in Jinan, Jinan 250023, China) Briefly introduces the stealth mechanism of material stealing and the material requirements for material stealth technology, and shows that the conductive polymer material is One of the preferred materials for stealth materials, reviews the stealth of conductive polymer materials in radar. The application of infrared stealth technology.

Stealth technology is an interdisciplinary and comprehensive technology. It is a multidisciplinary system engineering involving electromagnetics, materials, energy conversion, information processing and other disciplines and technologies. It includes shape design, electronic countermeasure technology and the use of stealth materials as weapons. Three important aspects of the surface structure, over the years of research have shown that only by combining the above three aspects can we obtain better stealth effects. Stealth materials are the key to stealth technology. Currently, several new types of stealth are under development in the world military powers. Materials include: chiral materials, nano stealth materials, conductive polymer materials, ceramic absorbers, salt absorbents, polycrystalline iron fiber absorbers, plasma absorbers, etc., due to the structural diversity of conductive polymer materials, small and unique The physicochemical properties have aroused widespread attention in the scientific community. 4 Many new sciences and new technologies once discovered are quickly applied to military conductive polymer materials. Since their inception, they have been favored by military technology experts. So far, conductive polymer materials are gradually being used as stealth materials in aviation aviation. Day technology, this article introduces the application of conductive polymer materials in stealth technology.

1 Stealth Mechanism of Material Stealth Stealth technology is a new technology emerging in the aerospace field. It means reducing the signal reflection characteristics of stealthy targets or reducing the leakage of their own characteristic signals within a certain range, making it difficult to be detected by signal detectors. The key to the technology, including radar stealth, infrared stealth, and other stealth technology materials, is that it must be able to absorb, dissipate, and scatter all types of electromagnetic radiation. By designing reasonable material properties and structure, electromagnetic waves are absorbed when they pass through the material and are converted into heat energy to dissipate, so that electromagnetic waves are reflected as little as possible to the radar or various types of detectors; or the frequency of electromagnetic waves is changed to reflect electromagnetic waves The center frequency is far from the receiving frequency of the detector; or the leakage of the electromagnetic waves of the weapon equipment itself is reduced to achieve the purpose of stealth. Therefore, the research on the material stealth technology is to study the wave absorbing material, the shielding material and the wave-transmitting material according to the absorbing mechanism. Absorbing materials are divided into resistance-type wave-absorbing materials, dielectric-type wave-absorbing materials and magnetic medium-type wave-absorbing materials. The resistance-type wave-absorbing materials mainly rely on the conduction or leakage loss energy of materials in the electromagnetic field, and the smaller the volume resistivity of the materials, The better the wave absorption effect is, the lower the resistivity of the material is, but the reflection ability of the material is increased, so that the electromagnetic wave in the free space is hard to enter the interior of the material, and the purpose of absorbing the wave cannot be achieved. The dielectric wave absorbing material mainly depends on its electromagnetic field. The repetitive polarization loss energy, the dielectric constant of the dielectric material, or the loss tangent Improve the wave absorption rate, but the increase of the dielectric constant will lead to the material surface reflection ability is strong, not conducive to the absorption of electromagnetic waves into the material, in order to improve the absorption effect, only to try to improve the material dielectric loss tangent to the magnetic medium It has 1 electrical function and has good mechanical properties. The shielding effect of this shielding material has reached 4dB. The absorption of electromagnetic wave absorbing materials for electromagnetic field is mainly the hysteresis loss eddy current loss domain wall displacement loss, residual magnetic loss and resonance loss, etc. As a result of the combined effects of the loss, the magnetic absorbers used in the magnetic wave absorbing material are mostly magnetic materials such as ferrite carbonyl iron powder, metal cobalt powder, and the like, and the absorbing materials are adjusted by means of their different proportions with the binder. The parameters, to achieve the purpose of absorbing the electromagnetic shielding of shielding materials is the use of low-resistance conductor material to reflect and guide the electromagnetic energy flow, in the conductor material generates the current and magnetic polarization opposite to the source electromagnetic field, thereby reducing the source electromagnetic field The radiation shielding material used for general equipment is mostly metallic, but in weapons and equipment The use of metal shielding materials to produce a larger reflective surface, not easy to use as a shielding material, it is generally used non-metallic materials, mainly conductive polymer materials through the wave, mainly by reducing the dielectric constant and dielectric loss angle The tangent value to achieve the material requirements of the 2 material stealth technology Absorbing materials for stealth materials can be divided into coated wave absorbing materials and structural wave absorbing materials depending on the application, the key is to select and adjust the complex dielectric parameters of the material (, X, in order to meet the electric performance requirements of absorbing materials, in order to meet the special requirements of various aircrafts for strong practicality, the microwave absorbing materials must have characteristics of light weight, high wave-absorption stability, good designability, etc., and conductive polymer materials. Due to its diversified structure, unique physical and chemical properties, and strong designability, conductive polymer materials are just one of the materials that meets the requirements.

3 The application of conductive polymer materials in stealth technology The conductive polymer materials can be divided into intrinsic conductive polymer materials and composite conductive polymer materials according to their composition and conductive mechanism. The intrinsic type electroconductive polymer material refers to a polymer material having a conductive property or a conductive function after being subjected to a doping treatment. There are mainly n-conjugated types, such as polyacetylene, linear polystyrenic polymers, etc.; metal-type chelates, such as poly-copper cyanide; and electron-transfer complexes, such as polycation Co-complexes, etc. It is difficult to process and synthesize conductive polymers, and it is still in the research stage. The limited application of composite conductive polymer materials, that is, conductive polymer composite materials, refers to the use of general-purpose polymers as substrates, through the addition of various conductive materials, Physical and chemical methods of multi-phase composite materials obtained after such conductive polymer materials due to processing convenience, relatively low cost, can design, get a relatively wide range of methods should be dumped to obtain composite conductive polymer materials, two One is that the matrix polymer is filled with various conductive fillers; the other is that the conductive mechanism of the conductive polymer or hydrophilic polymer and the matrix polymer blended with the conductive polymer composite material is relatively complex. Usually include three kinds of conductive channels, tunneling effects and field emission, the conductive performance is the result of the role of these three conductive mechanisms.

By adding different components and phases to the polymer material, the dielectric constants of the conductive polymer material can be adjusted to achieve the required requirements for the stealth material. The conductive polymer material is either in the structural stealth material or in the stealth paint material. Both have applications.

3.1 Application in Radar Stealth Technology British Plessey company uses polyurethane foam-based materials to dip carbon ink or graphite into LA-1 foam conductive polymer absorbing materials, and absorbs more waves in the 2 GHz to 18 GHz broadband frequency range. Well, it has been used on fuselage and wing of stealth aircraft. Wang Guoqiang et al. used conductive polymer and nano-scale magnetic material to compound and obtained materials with good absorbing effect. Experiments showed that nanocomposite is better than non-nanocomposite. , Shows unique properties, its structure is conducive to the absorption of electromagnetic waves on the one hand, on the other hand, the low density, ultra-thin thickness can better meet the needs of aerospace in order to reduce the production of engine wires and electronic equipment, etc. Electromagnetic leakage and wave-transmitting materials do not play a significant role in reducing the cross-sectional area of ​​the radar. They mainly use a large amount of radar absorbing material (RAM). The radar absorbing materials used are conductive polymer materials such as graphite epoxy resin. Aniline has become a conductive polymer due to its diversified structure, good environmental stability, easy processing, low cost, and special doping mechanism. Research hotspots. It has been applied to absorbing materials and electromagnetic shielding materials. In the United States made of polyaniline above China Huayin Technology Co., Ltd. developed a series of coatings, at 80, shielding effectiveness of 40dB ~ 60dB using conductive conductive polymers and doping semiconductor properties, reflection or absorption Electromagnetic waves have been patterned into camouflage fabrics with conductive polypyrrole fibers, which can interfere with enemy electronic surveillance.

Applying a conductive polymer coating on the inside or hole wall of an electronic device can increase its electrical conductivity to 10-1 S/cm or more, so as to achieve electromagnetic shielding inside and outside the device housing. Great changes in electrical conductivity before and after, to achieve the protection layer from the reflection of electromagnetic waves through the electromagnetic switch, to achieve the function of smart stealth 2 Infrared laser stealth technology for thermal stealth materials should have the following basic characteristics: meet the requirements Thermal infrared emissivity or strong temperature control capability; reasonable surface structure; low solar absorptivity; ability to be compatible with stealth requirements of other frequency bands; foreign research is more about coating type infrared stealth materials, followed by thin films Materials Infrared adhesives and infrared coating resins have the following characteristics: The fillers must be well protected and their infrared properties remain unchanged throughout the lifetime of the coating; secondly, the resin must be transparent to the infrared properties of the selected spectral range. Conductive polymers are more in line with requirements, so they are widely used in infrared stealth technology. Several types of conductive polymers are listed below. Composition and Infrared Stealth Effect The first material has a basic composition of Al X3m~18m; 0.623, and has visible light disguised Afc3 (3~7), organic alkyd (40~60) organic pigments (1.3-1.8) Other materials, the stealth performance index is Xlm-151m: 0.512Xlm-141m: 0520X.31m ~ 181m: 0-684, and has the characteristics of visible light disguise. The third basic material is Al foil (1 (!20, H101m) commercial colorless polyurethane paint, carbon black, and its stealth performance index is Xir: With the continuous development of thermal infrared technology, it is used for thermal camouflaging with low Radiating color paints are being studied. It has been reported that the low emissivity of heat-transparent adhesives and metallic pigments such as polyvinyl ethylene and vinyl acetate copolymers such as polypropylene nitride and metallic pigments is approximately 0. Radar Stealth Thermal Infrared Stealth conductive polymer material mainly consists of two layers. Generally, the surface layer contains 31 m51m81m141m low-emissivity pigments in the wavelength range, and the bottom layer contains carbonized boron, conductive graphite, conductive polyphenol aldehyde and other radar wave absorbers ( 75%-85%), Sh3 flame retardant (-8%) and rubber adhesive (7%-1%) In order to ensure the radar stealth performance of the composite coating, the electromagnetic parameters of the surface layer must be adjusted to reach the maximum Excellent impedance matching In addition, due to the use of boron carbide, the material also has the function of heat-resistant neutrons. This kind of coating is generally used on the surface of moving objects (such as aircraft missiles, vehicles).

Wide-band energy absorption camouflage rug should be thrown camouflage blanket bottom support layer, the middle is a metal reflective film, the surface of polyethylene material in the polyethylene layer is implanted with metal fibers bent mouse material for radar absorption properties of the radar Determined by the size of the small circle; the small circle's density, high and low reflect the ability of the material surface to reflect visible light, polyethylene layer containing radar absorber is generally thicker (about 2. 5mm), can be covered in Protected military equipment can also be used to create multiband false targets.

In the application of conductive polymer stealth materials, the United States has developed "ultra-black powder" nano-materials, the absorption rate of radar bands up to 99% plastic composites and graphite epoxy composites, not only good wave absorption performance, but also in It maintains good toughness at low temperatures.

Institute of Nanomaterials, Qingdao Institute of Chemical Technology, uses nanometals as catalysts to prepare conductive spiral chiral absorbers through polymerization. This is a new type of lightweight, broadband absorber that integrates nanometer, conductive polymers and spiral chiral. . Due to the effect of the spiral, this kind of absorbent not only has a strong effect on the wave-absorbing layer, but also has the advantages of good processability and convenient use. The material is based on the color and light intensity of the two atmospheric windows of the Pu-M15m Pu material. With it. The application of cnkibookmark4 conductive polymer materials in smart stealth materials should be used to reduce the quality and cost of the electronic system itself. Using smart fiber strong polymer as the stealth structural material not only reduces the cross section of the radar scattering, but also The quality of the aircraft has been reduced by 50, and the sound waves have good stealth effects. The success has been achieved by embedding high-activity diacetylene segments in polyurethane molecules. Under appropriate conditions, diacetylene is polymerized into polybutadiene. Diacetyl, which changes the technology of the entire material and applies it to stealth technology. 4 Conclusion Future war is a war under high-tech conditions, and the battlefield environment becomes more and more complex. Various types of radar advanced detectors and precision guided weapons were introduced. Various types of weapons constitute a serious threat. In order to improve the viability and combat effectiveness of weapons and improve combat effectiveness, all the major military powers in the world are developing stealth technologies. Since the 1950s, the United States has conducted research on stealth technology and began research in the 1970s. Stealth aircraft, stealth bombing of F117A stealth bombardment of 80s stealth aircraft equipped troops on active aircraft The machine, the B-2 strategic bomber, and the new F-22 advanced stealth fighter all use different stealth materials. China has started late in stealth technology research. With the deepening of research on the conductive mechanism of conductive polymer materials, due to the extremely strong designability of conductive polymer composite materials, it will be more fully applied in stealth technology. China must make a difference in this regard and develop its own stealth technology and materials.