The method of receiving radio-absorbing material
(57) Abstract:The invention relates to the absorbers of electromagnetic waves, in particular to methods of producing a multilayer nonwoven materials. The method of receiving radio-absorbing material allows you to extend the range of the lengths of the absorbed electromagnetic waves, to simplify and intensify the process by pre-molding canvases of synthetic fibers, dispersion of carbon fibers in a liquid or gaseous medium, filtering the dispersion through the canvas, synthetic fibers or styling ribbon electrically conductive materials on the canvas, of synthetic fibres Assembly of a multilayer stack of at least two non-woven synthetic canvases, one of which put a layer of carbon fibers or ribbons of conductive material so that the layer of carbon fibers or tapes electrically conductive materials alternated with a layer of canvas, of synthetic fibers, with subsequent perforation of the assembled multilayer stack of needles. 6 C.p. f-crystals, 7 ill., table 1. The invention relates to the absorbers of electromagnetic waves and means of masking, and more specifically to methods for mn is awewsome properties in a wide range of electromagnetic radiation (EMR). The invention can be used in the manufacture of protection from the adverse effects of EMP.Known absorber of electromagnetic waves and method of its manufacture, which allows to reduce the prominence when the radar in a wide range of frequencies  . A method of producing an absorber EMP includes mating hollow crests on dvukhfotonnoi machine parallel to each other, and stitch 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 radar absorbing properties of the material are not shown. The disadvantage of this method is the complexity of technology and the high cost of conducting filaments.The closest to the technical nature of the claimed is a method of receiving radio-absorbing material, comprising obtaining a blend dielektricheskoi 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% vol. Dielectric filaments embedded in a flat layer, protrude above the ends of the carbon fibers at 5-2 mm . The method of preparation of the blend of fibers and the implementation of the threads perpendicular to the flat layer in the description of the invention is not disclosed. There is a method allows to obtain materials with a minimum reflectance of ELECTROMAGNETIC radiation at a frequency of 10 GHz -19,2 dB.The disadvantage of this method is the complexity of technology and the narrow range of lengths absorbed electromagnetic waves.The technical problem on which this invention is directed, is the expansion of the range of the lengths of the absorbed electromagnetic waves, simplification and intensification of the process.The problem is solved in that in the method of receiving radio-absorbing material, comprising forming a multilayer non-woven fabric of synthetic and carbon fibers, a blend of synthetic and carbon fibers do not produce pre-formed into a canvas of synthetic fibers, Donskih fibers for drawing on the canvas specified number of carbon fiber or put tape electrically conductive materials, then collect layered package of at least two non-woven canvases, at least one of which put a layer of carbon fibers or ribbons of conductive material, the assembled package is covered with a canvas made of synthetic fibers and needles pierce. Filtering the dispersion of carbon fibers through the canvas of synthetic fiber produced by drawing it on the canvas, laid on a perforated substrate for separating the dispersion medium.Preliminary molding of the canvas, of synthetic fibers carried by wind or mechanical application of polyester fibers or a blend of polypropylene and polyester fibers onto the conveyor with the subsequent binding hypoproteinemia and/or heat treatment to thermostat.Filtering the gas dispersion on the surface of the canvas of dielectric fibers are produced by feeding carbon fibres carding machines, air jet onto the conveyor.The Assembly of a multilayer stack of several non-woven canvas with a layer of carbon fiber or foil is produced so that the layer of carbon fibers or tapes electrically conductive materials (foil) Cherepovetskaya permeability layers) increased from layer to layer from top to bottom.Prokalyvanie package needles is at a depth of 4-8 mm in the downward direction or toward each other with a density of 100 to 500 punctures on 1 cm2.The invention is illustrated in the schemes and examples.Fig. 1. Assembly diagram of the multilayer stack in the manufacture of radar absorbing material.1, 3, 5, 7 - canvas synthetic (dielectric) fibers, 2, 4, 6 - layer carbon(conductive) fibers or ribbons of electrically conductive materials.Fig. 2. Assembly diagram of the multilayer stack in the manufacture of radar absorbing material.1, 3, 4, 6 - canvas synthetic (dielectric) fibers, 2, 5 - layer carbon(conductive) fibers.Fig.3. Radio-absorbing properties of the material of example 1.Fig.4. Radio-absorbing properties of the material according to example 4.Fig.5. Radio-absorbing properties of the material according to example 5.Fig.6. Radio-absorbing properties of the material according to example 6.The technical proposal. A positive effect is achieved by introducing in the non-woven fabric, which in this case, the dielectric matrix with electrophysical properties close to the characteristics of the nation two types of input in the non-woven fabric, conductive components provides a wider range of absorption of electromagnetic radiation, penetrating into the material and create interference effects, providing a minimum reflectivity at the desired frequency AMY.In the non-woven fabric is set in a certain way by descending order of concentration from the boundary between "material is securable to the external surface of the material is divided conductive particles of the absorber consisting of a carbon fiber.Electromagnetic wave incident on such material penetrates into it without reflection, due to the proximity of the dielectric characteristics of free space and the dielectric matrix in the upper layers which low concentration of absorbing particles that affect these characteristics.As the distribution in depth of the material wave interacts with the absorbent particles, and they heat up due to the loss of their energy.Due to the gradual increase of the concentration of the absorber, the lack of sharp boundaries between layers of the electromagnetic wave is virtually no reflection in the material and there is damped with corresponding changes in the amplitude and length.Example 1. Get a radar absorbing material Assembly chetyrehkolka formed in accordance with table four canvas surface density (weight) of 100-200 g/m2of synthetic fibres mechanically and fasten by hypoproteinemia with a density of 180 cm-2. The formation of the canvas And In the produce of polyester staple fibers, canvas D - from a blend of polyester and polypropylene fibers. Canvas D from a blend of polyester and polypropylene fibers additionally thermoablative at 170oC for 3 minutes to seal. Carbon fiber length of 20 mm was dispersed in 5% aqueous solution of surface-active substances OS-20. Dispersion with a content of carbon fiber, 2 g/l filtered through the canvas of synthetic fibers in amounts corresponding data table. For this purpose, each canvas is placed on a perforated substrate and pour the appropriate amount of water dispersion of carbon fiber. Then the canvas is dried and collected in a four-layer package so that the layer of carbon fibers alternated with a layer of synthetic fibers and the content of carbon fibers (dielectric constant) increased from layer to layer from the top down (in the direction opposite to the direction of propagation of the electromagnetic wave). Four-layer package fasten by hypoproteinemia to a depth of 6 mm with a density of 300 cm-2.Example 2. Get a radar absorbing material of example 1, but the preliminary molding of the canvas provide an aerodynamic way. The dependence of the coefficient of reflection of radio waves from the frequency of the ELECTROMAGNETIC radiation similar to that shown in Fig.3.Example 3. Receive radio-absorbing material according to example 1 or 2, but after filtering the dispersion of carbon fiber through pre-molded cloth made of synthetic fibers on it is placed next canvas made of synthetic fibers and again carry out the filtration of a dispersion of carbon fiber for the application already fewer of the latter in accordance with the table. The dependence of the coefficient of reflection of radio waves from the frequency of the ELECTROMAGNETIC radiation similar to that shown in Fig.3.Example 4. Receive radio-absorbing material according to example 1 or 2, but after molding canvases from synthetic fibers and filtering water dispersion of carbon fibers collect multilayer package (Fig.2), in which the layer 1 and 5 is formed of synthetic (polyester) fibers, and layers 3 and 6 is formed from a synthetic (polyester) fibers, which filtered air disperse the CSOs fiber length of 5 mm at a rate of 13 g/m2.The dependence of the coefficient of reflection of radio waves from the frequency of the ELECTROMAGNETIC radiation shown in Fig. 4. Radio-absorbing material according to example 4 has a reflection coefficient AMY less than -10 dB in the frequency range from 5 to 30 GHz, which is considerably wider frequency range radiopalmwine materials obtained by known methods [1, 2].Example 5. Receive radio-absorbing material according to example 1 or 2, but of the two canvases of synthetic (polyester) fibers, one of which is applied by filtering water dispersions put a layer of shredded carbon fiber length of 200 μm in the amount of 7,010-3g/cm2. The dependence of the coefficient of reflection of radio waves from the frequency of the ELECTROMAGNETIC radiation shown in Fig.5. Radio-absorbing material according to example 5 has a reflectance AMY about 20 dB at a frequency of 15 GHz, which corresponds to the level of radiopalmwine material obtained by a known method  , when obviously the simpler the technology of its production.Example 6. Receive radio-absorbing material according to example 1 or 2, but instead of carbon fiber on the pre-molded cloth made of synthetic fibers are placed tape conductive material is aluminum foil or metalized p is cake 10x10 mm with decreasing cell size in the direction opposite to the direction of propagation of the incident electromagnetic wave. The dependence of the coefficient of reflection of radio waves from the frequency of the ELECTROMAGNETIC radiation shown in Fig.6.Literary sources
1. The absorber of electromagnetic waves and method of its manufacture. Pat. RF 2119216, CL H 01 Q 17/00, 19982. The method of receiving radio-absorbing material. Pat. The USSR 1790795, CL H 01 Q 17/00, 1990 1. The method of receiving radio-absorbing material comprising an Assembly of a multilayer non-woven fabric of synthetic and carbon fibers, wherein the pre-formed into a canvas of synthetic fibers, dispersed carbon fiber in a liquid or gaseous medium, filtering the dispersion through the canvas, synthetic fibers or put tape electrically conductive materials on the canvas of synthetic fibers, collecting the multilayer package, at least two non-woven canvases, of synthetic fibres, one of which is coated with the layer of carbon fibers or tapes electrically conductive materials, thus, to the layer of carbon fibers or ribbons of conductive material interspersed with canvas made of synthetic fibers and assembled multilayer package was covered Holst receiving radar absorbing material p. 1, wherein the preliminary forming of the canvas, of synthetic fibers carried by wind or mechanical application of polyester fibers or a mixture of polypropylene and polyester fibers onto the conveyor with the subsequent binding hypoproteinemia and/or heat treated.3. The method of receiving radio-absorbing material under item 1, characterized in that the filtering liquid dispersion of carbon fibers through the canvas of synthetic fibers produced by irrigation on a perforated substrate for separating liquid.4. The method of receiving radio-absorbing material under item 1, characterized in that the dispersing carbon fibers in a gaseous environment carried out by the flow of air in the process of scratching on the carding machine.5. The method of receiving radio-absorbing material under item 1, characterized in that the Assembly of a multilayer stack of several non-woven canvas made of synthetic fibers coated with a layer of carbon fibre or film of electrically conductive material is produced so that the layer of carbon fibers or ribbons of conductive material interspersed with canvas made of synthetic fibers and the content of the>/P>6. The method of receiving radio-absorbing material under item 1, characterized in that as the strips of conductive material using a foil or metallized polymeric film.7. The method of receiving radio-absorbing material under item 1, characterized in that the assembled multilayer package puncture needle with one or two sides, with a density of punctures 100500 cm-2.
FIELD: radio-electric engineering.
SUBSTANCE: cover is formed in form of layer on basis of fiber, placed between outer and inner layers of dielectric materials. Fiber layer along thickness is formed of several cloths of textile material of synthetic filaments with carbon cover with specific electrical, in which adjacent cloths are interconnected by inserts of given thickness on basis of dielectric connecting substance. Outer layer is made of rubber. Inner layer is made of dielectric connecting substance, containing granulated material, weakening reflection of electro-magnetic waves, in amount of 5-25% of total.
EFFECT: higher efficiency.
3 cl, 1 dwg
FIELD: composite materials.
SUBSTANCE: invention discloses a method for manufacturing composite material for shielding-mediated protection against electromagnetic emission and can be used in electronics, in radio engineering, and also in a series of special-destination articles. In addition, material may be used for anechoic boxes and in various assemblies of technical devices and radio apparatuses. Method comprises mixing modified graphite-containing conducting filler and polymeric binder at weight ratio (50-80):(20-50). Once ingredients combined, mixture is additionally subjected to thermal expansion in thermal shock mode at 250-310оС and then molded. Polymeric binder is selected from polyolefins, polystyrene, fluoroplastic, polyvinylchloride paste and modified graphite is product obtained by modifying graphite with concentrated sulfuric and nitric acids. Material is characterized by that, in wavelength band from 2 to 5 cm at thickness of material up to 0.1 mm, transmission coefficient is decreased from -40 to -85 dB.
EFFECT: improved performance characteristics.
6 cl, 1 tbl, 2 ex
FIELD: electromagnetic radiation protection.
SUBSTANCE: invention relates to a method of preparation and to composition of magneto-dielectric materials absorbing electromagnetic emission. Composition is prepared by combining binder with superdispersed magneto-dielectric filler, in particular composite product obtained through caking at 1150-1250°C followed by disaggregation of cake composed of magnetic particles of ferrite material (61.5-86.7 vol %) obtained by chemical precipitation of ferrite phase from aqueous solutions, the rest being layers of dielectric oxides precipitated onto surface of magnetic particles by way of nanomolecular layering from gas medium. Invention further discloses composition including 65-75 vol % of superdispersed magneto-dielectric filler along with binder prepared by above-indicated method.
EFFECT: increased choice of electromagnetic radiation-protection materials.
2 cl, 3 tbl, 12 ex
FIELD: electromagnetic radiation protection.
SUBSTANCE: invention relates to a method of preparation and to composition of materials absorbing electromagnetic emission. Composition is prepared by combining binder with ferrite, the latter containing 60-90% of ferrite material obtained according to high-temperature ceramic technology and ground to microparticle size and 10-40% of particles belonging to ferrite phase obtained by chemical precipitation from aqueous solutions onto surface of ferrite material microparticles. Ferrite is calcined in the form of isolated precipitate at 500-600°C and then disaggregated. Invention further discloses ferrite-based composition containing 9-13% binder obtained by above-indicated method.
EFFECT: increased choice of electromagnetic radiation-protection materials.
2 cl, 5 tbl, 12 ex
FIELD: shipbuilding; devices reducing probability and range of detection of ship by enemy radar systems.
SUBSTANCE: ship has metal hull and superstructure which is made from multi-layer polymer composite material. Ratio of superstructure area to hull area shall be no less than 0.54; metal members built in superstructure are coated with radio-absorbing external layer. Open cavities in hull and in superstructure are provided with detachable shields made from material reflecting the radio waves. Provision is made for forming false radar targets for receiving enemy missiles and effective protection of personnel against radiation of own radar facilities.
EFFECT: enhanced efficiency and safety.
FIELD: antennae equipment.
SUBSTANCE: device is in form of a structure composed of cardboard pipe-like elements of various length and diameter and wedge-like inserts, positioned inside pipe-like elements. Said elements are gathered in blocks in parallel to their axis, have inner diameter 66 and 200.4 mm, one slant at 17 degrees angle or two slants symmetric to element axis at angle 35 degrees, outer and inner electric-conductive layer.
EFFECT: higher efficiency, broader functional capabilities.
8 cl, 11 dwg, 1 tbl
FIELD: radiation-absorbing coatings.
SUBSTANCE: proposed radiation-absorbing coating has rubber base three-layer flexible plate made of ferrite powder, content of the latter being different in each layer. Third layer has in its composition 10 - 15 volume percent of gralene fiber. Coating also has fourth layer abutting against metal surface of piece of equipment being protected which is made of magnetically hard rubber of arch-type magnetization whose magnetic energy corresponds to maximum of energy product (BH)max = 4 - 8 kJ/m3. Coating may have metal or ceramic magnets in fourth layer. Process for manufacturing radiation-absorbing coating includes production of each layer of plate, joining of three first layers by co-curing, magnetization of fourth layer, and installation of metal or ceramic magnets therein; fourth layer is magnetized by way of arch-type saturation whereupon this layer is attached to plate assembled of three first layers with aid of adhesive.
EFFECT: facilitated installation on and removal from machine armor, improved radiation absorbing properties within wide frequency band.
3 cl, 4 dwg, 1 tbl
FIELD: materials transmitting or trapping electromagnetic beams of definite wavelength and bandwidth for research and industrial applications.
SUBSTANCE: proposed method for producing membranes capable of passing or trapping electromagnetic radiation of definite wavelength λ and bandwidth Δλ to obtain frequency-selective membranes with any composite pattern on any insulating substrate and in any quantity includes coating insulating substrate with low-resistance paste of desired pattern. Used as low-resistance paste is low-viscosity stabilized conducting compound of ultra-dispersed powders, polymeric binder having steady electric conductivity and average particle size of 10 - 600 nm, organic solvent, and surface-active materials, proportion of ingredients being as follows, parts by mass: ultra-dispersed conducting powder, 60 - 90; polymeric binders, 39 - 7; organic solvent, 100 - 400; and surface-active materials, 1 - 3. This compound is applied by means of printer or plotter according to desired program to produce desired pattern whose layer thickness is not smaller than that of skin layer for final procedure, it is dried out.
EFFECT: enlarged functional capabilities.
1 cl, 2 tbl
FIELD: protection from electromagnetic emission.
SUBSTANCE: mesh of electric-conductive material is positioned on dielectric transparent film with applied transparent electric-conductive layer, made either of indium, or of tin, or of indium/tin alloy with thickness, approximately equal to 0,1 of skin layer, and the very mesh is applied with thickness not exceeding skin-layer by printer or plotter using electric-conductive compound, consisting of ultra-dispersive electric-conductive powder with stable electric conductivity and average size of particles 10,0-600,0 nm, polymer linking component, organic solvent and surfactant with certain ratio of components.
EFFECT: forming of transparent screens, screening properties of which do not depend on falling angle of electromagnetic emission, also light and simple to manufacture.
FIELD: reduced probability of weapon and other war materiel location by radar.
SUBSTANCE: controllable layer is made in the form of thin film of evaporated graphite and disposed between first and second insulating layers; first bidimensional-periodic lattice made of evaporated metal strips is disposed on external side of first insulating layer; second bidimensional-periodic lattice made of evaporated metal strips is disposed between second and third insulating layers; other side of third layer carries reflecting screen; conductivity B1 of first bidimensional-periodic lattice and thickness d1 of first insulating layer ensuring minimal level of echo signal in desired frequency band are chosen from mathematical expressions given in description of invention. Thicknesses of second and third insulating layers d2 and d3 of second and third insulating layers, respectively' as well as refractive indices of first, second, and third insulating layers n1, n2 n3, respectively, are chosen from expressions given in description of invention.
EFFECT: reduced cost of coating.
1 cl, 5 dwg