A method of producing an absorber of electromagnetic radiation

 

(57) Abstract:

The method allows to increase the absorptive capacity of the material in the length range of electromagnetic waves 2,5-36 GHz and to simplify the technological process. This technical result is reached by making the blend of fibers in three stages, the first of which put carbon fiber on the dielectric manually scraps of 0.5 to 1.0 g, the second conducting rough ploughing with weight control bits to reduce their mass to 0.01 g, the third conducting thin loosening and brushing blend, and the fixing structure of the canvas and duplication takes place simultaneously by piercing needles. 4 C.p. f-crystals, 3 ill.

The invention relates to methods of producing non-woven materials of the blend dielectric and conductive fibers having the property of absorbing electromagnetic radiation (EMR) in a wide frequency range. The invention is intended for the manufacture of structural elements or garments used for protection from the effects of EMP.

Known absorber of electromagnetic waves and method of its manufacture, allowing power reduction AMY in a wide range of frequencies [1]. The method of obtaining A rows of hollow ridges knit from a dielectric filament needles of one needle cases and hollow comb injected conductive thread with tension. Each hollow ridge additionally fill conductive threads with variable density altitude attainable by a change in the proportions between the dielectric and conductive fibers in the mixture. A method of obtaining a blend dielectric and conductive yarns and the filling ridges in the patent does not describe the characteristics of the basic material properties are not listed. The disadvantage of this method is the complexity of technology and the high cost of conducting filaments.

The closest in technical essence to the claimed is a method of producing an absorber of electromagnetic radiation, including bulk dielectric fibers and fibers (threads) carbon fiber "plan", cooking blend dielectric fibers and carbon fiber, molded double-layer fabric of the blend, and one layer of a thickness of 1-2 mm contains 6,8 about. % randomly arranged filaments "plan" length 2-5 mm, which is introduced perpendicular to the plane of the layer of dielectric thread length 20 mm and strands of fiber "plan" length 15-18 mm in fiber content "plan" layer 6,8-8,5 about. %. Dielectric filaments embedded in a flat layer, protrude above the ends of the carbon fibers at 5-2 mm [2]. How photokit. There is a method allows to obtain materials with a minimum reflectance of ELECTROMAGNETIC radiation at a frequency of 10 GHz is 19.2 dB.

The disadvantage of this method is insufficient absorption capacity of the material in the length range of electromagnetic waves from 2.5 to 36 GHz and technological complexity.

The technical problem on which this invention is directed, to increase the absorption ability of the material in the length range of electromagnetic waves from 2.5 to 36 GHz and simplify the process.

The problem is solved in that in the method of producing an absorber of electromagnetic radiation, including bulk dielectric and carbon fibers, preparation of a blend of fibers forming the nonwoven canvas, the fixation structure of the canvas and duplication, according to the invention the preparation of the blend fibers are in three stages, first put the carbon fiber on the dielectric manually scraps of 0.5 to 1.0 g, the second conducting rough ploughing with weight control bits blend of fibers and reduce their mass to 0.01 g, the third conducting thin loosening and brushing blend, fixing structure of the canvas and duplication takes place simultaneously by piercing and fibers over time, sufficient to reduce the mass of scraps to 0.01,

To prepare the blend of fibers using 0.5-15 wt.% carbon fiber, forming a non-woven canvas carry from a blend of fibers weighing 100-150 g/m2.

Fixing structure of the canvas and duplication takes place simultaneously by piercing needles with density punching above 5-20 cm-2below 20-100 cm-2.

Piercing duplicated canvases needles produce through in the direction perpendicular to the plane of the canvas, towards each other.

Duplicated canvases consistently stack the PA one side of the first canvas. When applying each subsequent layer package bonded canvases pierce for all thickness.

The invention is illustrated by examples and charts.

Fig.1. Radio-absorbing properties of the material according to example 1-3.

Fig.2. Radio-absorbing properties of the material in example 4-5.

Fig.3. Stealth properties of the composite material according to example 6.

The technical proposal. A positive effect is achieved by the inclusion in the non-woven fabric with small dielectric loss is raspredeleniya (dispersion) in a dielectric medium (synthetic fiber). Uniform distribution of carbon fibers in the synthetic fiber is due to the fact that the preparation of the blend fibers are in three stages, first put the carbon fiber on the dielectric manually Klochkov 0.5-1.0 g on the second conducting rough ploughing with weight control bits to reduce the average weight of scraps of less than 0.01 g, the third conducting thin loosening and brushing blend fibers. A special place in the proposed method takes the stage rough loosening when the speed of movement of the conveyor 0.1-0.5 m/min and weight control bits of carbon fiber in the amount of polyester. For quality control of mixing in the process of loosening take samples from 15-20 Klochkov, weigh and determine their average weight. The average weight of one piece should not be more than 0.01, In case of discrepancy of this parameter gross loosening repeat again. Radio-absorbing properties of the material obtained by the proposed method significantly depends on the quality of mixing of components.

Absorbing properties are enhanced, and their frequency response is substantially improved (aligned) with the duplication of non-woven sheets with evenly distributed in the volume of carbon fiber.

The invention is illustrated by the following examples.

Examples 1-3. Get an absorber of electromagnetic radiation from a blend of polyester and carbon fibers. Pre-hung components in the ratio, providing the concentration of the carbon fibers in the mixture 6, 9 and 12 wt.% respectively. Cut polyester fiber 0.33 Tex has the following parameters: diameter of 10-15 μm and a length of 3-3,5 cm Cut carbon fiber brand "Plan-9" is characterized by a diameter of 5-10 μm and a length of 3-3,5 cm

The belt conveyor unload polyester fiber and hand-laid carbon fiber for polyester in the form of pieces of a mass of 0.5-1.0, Spend gross loosening when the speed of movement of the conveyor 0.2 m/min with weight control bits of carbon fiber in the amount of polyester. To control take samples from 15-20 bits and determine their total and average mass. The average weight of one piece should not be more than 0.01, In the case of non-compliance with this parameters the points fibrous mass into smaller structural elements and mixing them together spend loosening of the fibers in a thin Ripper. The mixture of fibers thin after loosening served on veloceprod in the drive before carding unit. From the drive fibrous mass is fed into the carding machine for its separation into individual fibers and ensure uniform and uninterrupted supply in the disconnected state at the stage of formation of the canvas. The degree of separation (tangle free) and mixing fibers regulate by changing the speed of rotation of the working bodies of the carding machine (replacement removable sprockets and pulleys) and the wiring between the main and removable-chechoseme rolls.

In the process of forming non-woven canvas carry out removal of fibers from the removable-kasumiga shaft, transported in suspension in the air stream in the chamber of the wind consoles for the formation and deposition of fibers on the air-permeable supporting surface in the form of fibrous canvas (layer) with chaotic arrangement of fibres in the material weighing 150 g/m2.

The surface density change by regulating the speed of movement of the conveyor blade at a constant performance carding machines. After the formation of the canvas provide a fixing structure of bilateral about the studied 22 cm-2. The absorber of electromagnetic radiation as in example 1 placed on a conductive surface and measure the reflection coefficient of electromagnetic radiation from a frequency in the range from 2.5 to 37.5 GHz. The dependence of the reflection coefficient of electromagnetic radiation of frequency is shown in Fig.1.

Examples 4-5. Get an absorber of electromagnetic radiation as in example 1, but pre-hung components in the ratio, providing the concentration of the carbon fibers in the mixture is 3 and 15 wt.% respectively, and is formed into a sheet with a surface density of 100 g/m2. The dependence of the reflection coefficient AMY on the frequency and composition of the material shown in Fig. 2. In the frequency range from 3 to 36 GHz absorbing properties of the material containing 15 wt.% carbon fiber is considerably higher than that of the material containing 3 wt.% carbon fiber, and in the range from 5.5 to 36 GHz absorbing properties of the material containing 15 wt.% carbon fiber is higher than that of the material obtained by a known method.

Example 6. Get an absorber of electromagnetic radiation as in example 1, but using carbon fiber brand "Avlon-2" (diameter 5-10 mm, length 3-3,5 cm). Form Paralimni car brand "beech Okoume".

The dependence of the reflection coefficient AMY frequency shown in Fig.3. Absorbing properties of the composite material containing carbon fiber is higher than that of the material obtained according to the method in all the investigated wavelength range from 2.5 to 37.5 GHz.

Examples 7-8 (control). Get an absorber of electromagnetic radiation as in example 1, but hung components in the ratio, providing the concentration of the carbon fibers in the mixture is 0.2 and 25 wt.%. The reflection coefficient AMY frequency of 10 GHz is 2 and 3.5 dB, respectively.

Examples 9-10 (control). Get an absorber of electromagnetic radiation as in example 1, but the mixture is carried out without prior pickup carbon fiber, and cultivation is carried out for 5 minutes without size control bits of carbon fiber. The reflection coefficient AMY frequency of 10 GHz is more than 5 dB.

Literary sources

1. The absorber of electromagnetic waves and method of its manufacture. Pat. RF 2119216, CL H 01 Q 17/00, 1998

2. The method of receiving radio-absorbing material. Pat. The USSR 1790795, CL H 01 Q 17/00, 1990

1. A method of producing an absorber of electromagnetic radiation, including the hundred, fixing structure of the canvas and duplication, characterized in that the preparation of the blend fibers are in three stages: first put the carbon fiber on the dielectric in the form of scraps of 0.5 to 1.0 g, the second conducting rough ploughing with weight control bits blend of fibers, the third conducting thin loosening and brushing blend, and the fixing structure of the canvas and duplication takes place simultaneously by piercing needles.

2. A method of producing an absorber of electromagnetic radiation under item 1, characterized in that the coarse loosening spend with weight control bits blend of fibers for a time sufficient to reduce the mass of scraps to 0.01,

3. A method of producing an absorber of electromagnetic radiation under item 1, characterized in that for the preparation of blend fibers using 0.5-15 wt.% carbon fibre.

4. A method of producing an absorber of electromagnetic radiation under item 1, characterized in that the formation of woven canvas carry from a blend of fibers weighing 100-150 g/m2.

5. A method of producing an absorber of electromagnetic radiation under item 1, characterized in that the piercing needles carried out with density

 

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