"Pretender" in military textiles

Camouflage technology is a technical measure to conceal oneself and deceive the enemy to take all kinds of false and false detections, and is an important means to guarantee the combat effectiveness of the army. Stealth technology is a comprehensive technology that changes the detectable information characteristics of targets such as weapons and equipment, making it difficult for enemy detection systems to find. Stealth technology is the promotion of camouflage technology. The modern camouflage technology is mainly used to reduce the technical interference measures taken by the difference between visible light, laser, thermal infrared, electromagnetic wave and other aspects.

1, laser stealth technology

Laser stealth is to make the target less detectable by reducing the reflection and scattering signals of the target to the laser. The focus is on reducing the target's lidar scattering cross section LRCS and laser reflectivity. Among them, LRCS comprehensively reflects the influence of various factors such as laser wavelength, target surface material and roughness, target geometry shape on the target laser scattering characteristics, and is the main index used to characterize the target laser scattering characteristics.

There are two main types of laser stealth technology. Structure type: The structure is designed as an absorption type multi-layer sandwich, or the composite material is made into a honeycomb shape, a corrugated shape, a laminated shape, a cone-shaped shape, etc., when the laser is returned from the structural end, the special structure of the material can reduce the reflected laser light. The strength of the signal, which in turn extends the arrival time of the reflected laser. Coated type: Reduces the reflection of the target on the laser.

Laser stealth mainly refers to the stealth of 1.06, 1.54, 10.6μm laser, of which 1.06μm laser stealth is the most important, because the current laser guided weapon working wavelength is mainly 1.06μm. If the coating is capable of reducing the laser diffuse reflectance at these wavelengths, it will have a significant laser stealth effect.

Laser stealth materials are mainly divided into two types: absorbing materials and nano materials. Absorbing materials are mainly used to absorb light waves that are incident on a target. The absorption capacity depends on the magnetic permeability and dielectric constant of the material, and the absorption wavelength depends on the thickness of the material. Nanomaterial refers to a material with a characteristic size of 0.1-100 nm. It has excellent absorbing properties, and has the characteristics of frequency bandwidth, good compatibility, small mass and thin thickness.

2, anti-heat infrared stealth technology

Infrared radiation refers to electromagnetic waves with a wavelength of 0.78 to 1000 μm, also known as thermal radiation, which is the most extensive radiation in nature. As long as the temperature of the object is above absolute zero (-273 ° C), the molecules that make up them are constantly making irregular thermal motion and continuously emitting thermal infrared radiation. The most effective way to prevent infrared reconnaissance is to try to make the infrared characteristics of the target as close as possible to the infrared characteristics of the background, so that it is difficult to distinguish the target from the background object by means of thermal infrared reconnaissance.

Since the radiation of general military targets is stronger than the background, the use of low emissivity coatings can significantly reduce the target's infrared radiation energy. On the other hand, a thermal infrared stealth coating is used to lower the target surface temperature.

Infrared stealth coating materials are mainly divided into two categories: absorption type, through the coating itself or some structure and process technology, so that the absorbed energy is continuously consumed or converted inside the coating without causing obvious temperature rise, reducing the heat radiation of the object; The type, after absorbing the infrared energy, changes its reflection direction, or shifts the infrared radiation released after absorption to the long wave, so that it is outside the working band of the infrared detection system, and finally achieves the purpose of stealth.

3, anti-electromagnetic wave technology

Preventing the interference of high-frequency electromagnetic fields can improve the safety performance of equipment such as precision electronic weapon equipment, and ensure the safety and smoothness of systems such as network systems, transmission systems, and weapon platforms, as well as the importance of personal safety protection.

May be the high frequency electromagnetic wave shielding fabric has two types: shielded functional fiber woven fabric; finishing manner in a process of shielding fabric.

Electromagnetic shielding fabrics woven from metal fiber blended yarns are an effective method for shielding electromagnetic waves. At present, the wire contained in the electromagnetic wave shielding fabric is mainly stainless steel fiber and nickel fiber, and the fiber diameter is about 4 to 10 μm. The mixing ratio of the wire is 20% to 30%, but the metal fiber has a hard hand feeling, a large friction coefficient, a large density, a strong rigidity, and the toughness, curl, poor elasticity, and poor cohesion of the fiber are generally suitable for Ordinary 21s ~ 40s fiber blending, but the spinnability is much more difficult than ordinary fiber, we must further explore the production process, improve the spinning quality, improve production efficiency and yield.

The electroless plating method requires the roughening, sensitization and activation pretreatment of the fabric after desizing and degreasing. The electroless plating process is used to produce electromagnetic shielding fabrics with high electrical conductivity, and the electromagnetic wave is mainly caused by reflection loss.

4, anti-radar wave stealth technology

The absorbing fabric designed for anti-radar reconnaissance must be able to have a large loss of electromagnetic waves, minimize the electromagnetic wave reflectivity of the coating, and have the effect of interference between the electromagnetic waves reflected by the metal substrate and the reflected waves on the surface of the coating. This reflection is performed multiple times at the interface of the two materials. In short, the electromagnetic attenuation of electromagnetic absorbing materials is mainly based on the reflection of electromagnetic waves and the absorption of electromagnetic waves.

Anti-radar reconnaissance camouflage nets can be divided into several types, such as scattering type, absorption type and scattering/absorption type anti-radar camouflage net, according to different camouflage mechanisms. The anti-radar camouflage net adopts a shielding surface and a support structure. The metal mesh cloth and the absorbing coating are used to create a shielding effect to cover the real target under the shielding surface, so that only the shielding bright spots formed by the mesh surface appear in the radar display.

The scattering type anti-radar shielding net reduces the backscattering of the incident radar wave by the scattering of the mesh surface, and makes the backscattering coefficient of the mesh surface close to the average backscattering coefficient of the background, so that the radar is difficult to identify the target.

The absorption type anti-radar network uses radar wave absorbing material to convert and absorb incident electromagnetic waves through the conductance loss, high-frequency dielectric loss and hysteresis loss inside the material, and reduce the surface reflection of radar electromagnetic waves, so that the radar can not detect the camouflage net. The real goal under.