EP0924798A1 - Composite radar absorbing material and use of such a material - Google Patents

Composite radar absorbing material and use of such a material Download PDF

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Publication number
EP0924798A1
EP0924798A1 EP98402984A EP98402984A EP0924798A1 EP 0924798 A1 EP0924798 A1 EP 0924798A1 EP 98402984 A EP98402984 A EP 98402984A EP 98402984 A EP98402984 A EP 98402984A EP 0924798 A1 EP0924798 A1 EP 0924798A1
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Prior art keywords
order
composite material
layer
thickness
structural composite
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EP98402984A
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German (de)
French (fr)
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EP0924798B1 (en
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Jean-Francois Escarmant
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Giat Industries SA
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Giat Industries SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/42—Housings not intimately mechanically associated with radiating elements, e.g. radome
    • H01Q1/422—Housings not intimately mechanically associated with radiating elements, e.g. radome comprising two or more layers of dielectric material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
    • H01Q17/004—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems using non-directional dissipative particles, e.g. ferrite powders
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
    • H01Q17/008—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems with a particular shape

Definitions

  • the technical sector of the present invention is that of structural composite materials absorbing radar waves.
  • One of the possible solutions to reduce possibilities of detecting a battle tank is to use covering or structural materials chests able to significantly reduce reflection of the incident radar wave.
  • the object of the present invention is to provide a structural composite material capable of absorbing incident radar radiation.
  • the impregnated folds are glass or Nylon® fibers associated with epoxy resins.
  • the composite material can have a thickness of the order of 4 to 10 mm.
  • the outer layer has a thickness of the order of 1.5 to 4 mm, the intermediate layer a thickness of the order of 0.5 to 2.5 mm and the layer internal thickness of the order of 1.5 to 3.5 mm.
  • the material composite has a total thickness of around 6.75 mm, the outer, intermediate and inner layers having the respective thicknesses of 2.75 mm, 1.5 mm and 2.5 mm.
  • the particles electrically conductive are carbon grains having a diameter less than 0.1 mm with a proportion less than 10% by mass.
  • the invention also relates to a use of this material for the manufacture of walls for armored vehicles endowed with a mechanical resistance resistant to a pressure of the order of 1 ton / cm 2 and providing an attenuation in reflection of radar waves greater than 10 dB.
  • such a composite material can be also used for the production of safety boxes easement or protection for armored vehicles.
  • the composite material according to the invention offers the advantage of replacing all the composites used on armored vehicles where there is a need for reduction of radar reflectivity is necessary. More radar absorption performance, it has all the mechanical strength characteristics of composites usual used on armored vehicles.
  • the material according to the invention can be used in particular to make batch boxes edge, flysheet and all double walls composites for thermal insulation and the evacuation of heat flows, for example at the rear near the exhaust.
  • the composite material according to the invention is obtained without modification of the current manufacturing process existing structural composites.
  • the concept of the invention is based on the adaptation of a multilayer structure allowing, through the play of internal resonances of the different layers, to obtain significant absorption over several frequency bands. It has therefore been found that a three-layer material offers a satisfactory compromise for obtaining radar absorption performance and mechanical performance.
  • an easement chest made with the material according to the invention can be walked on by a man equipped with his package, with a mass of the order of 100 kg, without causing breakage or permanent deformation, which represents a resistance to a pressure of the order of 1 ton per cm 2 .
  • the structural composite material 1 is applied to a support 2 formed by the wall of a armored vehicle (not shown).
  • the outer layer 3 is made of a material weakly reflecting non-magnetic dielectric radar, low dielectric loss and equipped with real dielectric permittivity on the order of 3. This layer must favor the penetration of the radar wave in structure by impedance matching.
  • a layer may consist of Nylon® fibers and a epoxy resin, for example.
  • the intermediate layer 4 consists of a non-magnetic dielectric material whose losses dielectrics are more important than those of the layer external 3, with a real dielectric permittivity of around 5.
  • the inner layer 5 is made of a material non-magnetic dielectric charged with carbon particles having a high electrical conductivity, and conferring to this material absorption of electromagnetic waves more important than those of the first two layers.
  • the actual dielectric permittivity of this layer is more important, of the order of 15 to 20.
  • the material 1 is completed in a known manner by a metal layer 6 consisting of an aluminum film on the order of 0.1 mm thick, for example.
  • Layers 4 and 5 are composites made at based on epoxy resin and E glass fiber fabric
  • the material 1 according to the invention can have a thickness of the order of 4 to 10 mm, advantageously 6.75 mm approximately.
  • the outer 3, intermediate 4 and internal 5 may have a thickness of 1.5 to 4 mm, 0.5 to 2.5 mm and 1.5 to 3.5 mm.
  • these three layers have thicknesses 2.75 mm, 1.5 mm and 2.5 mm respectively.

Abstract

A composite structural material, designed to absorb radar waves at frequencies of 8 - 18, 35 and 94 GHz. The composite structural material consists of at least three layers (3,4,5) of dielectric and nonmagnetic materials - an outer low reflective and low loss layer with an actual dielectric constant of about 3 to promote penetration of incident radar waves, an intermediate layer (4) with a dielectric constant of about 5, and an inner layer (5) filled with electrically conductive particles and having an actual dielectric conductivity of 15-20. The structure has an overall thickness of 4-10 mm, with the outer layer being 1.5-4.0 mm thick, the intermediate one 0.5-2.5 mm and the inner one 1.5-3.5 mm, with conductive particles in the form of carbon grains under 0.1 mm in diameter and in a proportion of less than 10 wt.%. The material is able to withstand a pressure of the order of 1 tonne/cm<2> and has a radar wave attenuation of over 10 dB.

Description

Le secteur technique de la présente invention est celui des matériaux composites structuraux absorbant les ondes radar.The technical sector of the present invention is that of structural composite materials absorbing radar waves.

On utilise actuellement sur le champ de bataille de nombreuses menaces mettant en oeuvre la détection et/ou le guidage par ondes radar. Ce sont les radars de terrain portés par un véhicule ou par un fantassin, les radars aéroportés sur hélicoptères, les auto-directeurs de missiles notamment à ondes millimétriques pour munitions dites intelligentes. Vis-à-vis de ce type de détection, le char de bataille moderne et tous les véhicules blindés de reconnaissance doivent être rendus les plus discrets possible.We are currently using on the battlefield of numerous threats implementing detection and / or radar wave guidance. These are the field radars carried by a vehicle or by an infantryman, radars airborne on helicopters, the self-directors of missiles including millimeter wave for ammunition say smart. Regarding this type of detection, the modern battle tank and all the armored vehicles of recognition should be made the most discreet possible.

Une des solutions envisageables pour réduire les possibilités de détecter un char de bataille consiste à utiliser des matériaux de recouvrement ou de structure de coffres aptes à atténuer de manière importante la réflexion de l'onde radar incidente.One of the possible solutions to reduce possibilities of detecting a battle tank is to use covering or structural materials chests able to significantly reduce reflection of the incident radar wave.

Une difficulté réside dans la conception d'un matériau composite ayant des propriétés d'absorption radar dans les bandes de fréquences utilisées actuellement sur le champ de bataille et qui sont situées à 8-18 GHz, à 35 GHz et à 94 GHz.One difficulty lies in the design of a composite material with radar absorption properties in the frequency bands currently used on the battlefield and which are located at 8-18 GHz, at 35 GHz and at 94 GHz.

On ne connaít pas actuellement des matériaux composites aptes à offrir une telle performance.We do not currently know materials composites capable of offering such a performance.

Le but de la présente invention est de fournir un matériau composite structural apte à absorber le rayonnement radar incident.The object of the present invention is to provide a structural composite material capable of absorbing incident radar radiation.

L'invention a donc pour objet un matériau composite structural apte à absorber les ondes radar de fréquences 8 à 18 GHz, 35 GHz et 94 GHz, ce matériau étant caractérisé en ce qu'il comprend au moins trois couches de matériaux diélectriques non magnétiques obtenues à partir d'un empilement de plis imprégnés :

  • une couche externe faiblement réflectrice et à faibles pertes ayant une permittivité diélectrique réelle de l'ordre 3, pour favoriser la pénétration des ondes radar incidentes,
  • une couche intermédiaire ayant une permittivité diélectrique réelle de l'ordre de 5,
  • et une couche interne chargée de particules électriquement conductrices et ayant une permittivité diélectrique réelle importante de l'ordre de 15 à 20.
The subject of the invention is therefore a structural composite material capable of absorbing radar waves of frequencies 8 to 18 GHz, 35 GHz and 94 GHz, this material being characterized in that it comprises at least three layers of non-magnetic dielectric materials obtained from a stack of impregnated plies:
  • a weakly reflecting and low loss outer layer having a real dielectric permittivity of the order of 3, to promote the penetration of incident radar waves,
  • an intermediate layer having a real dielectric permittivity of the order of 5,
  • and an internal layer charged with electrically conductive particles and having a high real dielectric permittivity of the order of 15 to 20.

Selon un exemple de réalisation, les plis imprégnés sont des fibres de verre ou de Nylon® associées à des résines époxy.According to an exemplary embodiment, the impregnated folds are glass or Nylon® fibers associated with epoxy resins.

D'une manière générale, le matériau composite peut présenter une épaisseur de l'ordre de 4 à 10 mm.Generally, the composite material can have a thickness of the order of 4 to 10 mm.

A titre d'exemple, la couche externe présente une épaisseur de l'ordre de 1,5 à 4 mm, la couche intermédiaire une épaisseur de l'ordre de 0,5 à 2,5 mm et la couche interne une épaisseur de l'ordre de 1,5 à 3,5 mm.For example, the outer layer has a thickness of the order of 1.5 to 4 mm, the intermediate layer a thickness of the order of 0.5 to 2.5 mm and the layer internal thickness of the order of 1.5 to 3.5 mm.

Selon un autre exemple de réalisation, le matériau composite présente une épaisseur totale de l'ordre de 6,75 mm, les couches externe, intermédiaire et interne ayant les épaisseurs respectives de 2,75 mm, 1,5 mm et 2,5 mm.According to another exemplary embodiment, the material composite has a total thickness of around 6.75 mm, the outer, intermediate and inner layers having the respective thicknesses of 2.75 mm, 1.5 mm and 2.5 mm.

D'une manière générale, les particules électriquement conductrices sont des grains de carbone ayant un diamètre inférieur à 0,1 mm avec une proportion inférieure à 10 % en masse.Generally speaking, the particles electrically conductive are carbon grains having a diameter less than 0.1 mm with a proportion less than 10% by mass.

L'invention concerne également une utilisation de ce matériau pour la fabrication de parois pour véhicules blindés dotées d'une résistance mécanique résistant à une pression de l'ordre de 1 tonne/cm2 et procurant une atténuation en réflexion des ondes radar supérieure à 10 dB.The invention also relates to a use of this material for the manufacture of walls for armored vehicles endowed with a mechanical resistance resistant to a pressure of the order of 1 ton / cm 2 and providing an attenuation in reflection of radar waves greater than 10 dB.

En variante, un tel matériau composite peut être également utilisé pour la réalisation de coffres de servitude ou de protection pour des véhicules blindés.Alternatively, such a composite material can be also used for the production of safety boxes easement or protection for armored vehicles.

Le matériau composite selon l'invention offre l'avantage de remplacer tous les composites utilisés sur les véhicules blindés aux endroits où un besoin de réduction de la réflectivité radar est nécessaire. En plus des performances d'absorption radar, il possède toutes les caractéristiques de tenue mécanique des composites habituels mis en oeuvre sur les véhicules blindés.The composite material according to the invention offers the advantage of replacing all the composites used on armored vehicles where there is a need for reduction of radar reflectivity is necessary. More radar absorption performance, it has all the mechanical strength characteristics of composites usual used on armored vehicles.

Ainsi, le matériau selon l'invention peut être utilisé notamment pour fabriquer des coffres de lot de bord, le double-toit et toutes les doubles parois composites destinées à l'isolation thermique et à l'évacuation des flux de chaleur, par exemple à l'arrière près de l'échappement.Thus, the material according to the invention can be used in particular to make batch boxes edge, flysheet and all double walls composites for thermal insulation and the evacuation of heat flows, for example at the rear near the exhaust.

Enfin, le matériau composite selon l'invention est obtenu sans modification du procédé de fabrication actuel des composites structuraux existants.Finally, the composite material according to the invention is obtained without modification of the current manufacturing process existing structural composites.

D'autres caractéristiques, détails et avantages de l'invention ressortiront à la lecture du complément de description qui va suivre d'un mode de réalisation de l'invention donné à titre d'exemple en relation avec des dessins sur lesquels :

  • la figure 1 est une vue en coupe montrant la disposition des couches du matériau composite selon l'invention, et
  • les figures 2 à 4 sont des courbes illustrant la performance d'atténuation des ondes radar de ce matériau composite dans les trois bandes de fréquences précitées.
Other characteristics, details and advantages of the invention will emerge on reading the additional description which follows of an embodiment of the invention given by way of example in relation to the drawings in which:
  • FIG. 1 is a sectional view showing the arrangement of the layers of the composite material according to the invention, and
  • Figures 2 to 4 are curves illustrating the attenuation performance of the radar waves of this composite material in the three aforementioned frequency bands.

Le concept de l'invention repose sur l'adaptation d'une structure multicouche permettant par le jeu des résonances internes des différentes couches d'obtenir une absorption importante sur plusieurs bandes de fréquences. On a donc trouvé qu'un matériau à trois couches offrait un compromis satisfaisant pour obtenir les performances d'absorption radar et les performances mécaniques. Ainsi, un coffre de servitude fabriqué avec le matériau selon l'invention peut être piétiné par un homme équipé de son paquetage, d'une masse de l'ordre de 100 kg, sans induire des cassures ou une déformation permanente, ce qui représente une résistance à une pression de l'ordre de 1 tonne par cm2. The concept of the invention is based on the adaptation of a multilayer structure allowing, through the play of internal resonances of the different layers, to obtain significant absorption over several frequency bands. It has therefore been found that a three-layer material offers a satisfactory compromise for obtaining radar absorption performance and mechanical performance. Thus, an easement chest made with the material according to the invention can be walked on by a man equipped with his package, with a mass of the order of 100 kg, without causing breakage or permanent deformation, which represents a resistance to a pressure of the order of 1 ton per cm 2 .

Sur la figure 1, le matériau composite structural 1 est appliqué sur un support 2 constitué par la paroi d'un véhicule blindé (non représenté).In FIG. 1, the structural composite material 1 is applied to a support 2 formed by the wall of a armored vehicle (not shown).

La couche externe 3 est constituée par un matériau diélectrique non magnétique faiblement réflecteur des ondes radar, à faible perte diélectrique et doué d'une permittivité diélectrique réelle de l'ordre de 3. Cette couche doit favoriser la pénétration de l'onde radar dans la structure par adaptation d'impédance. Une telle couche peut être constituée par des fibres de Nylon® et d'une résine époxy, par exemple.The outer layer 3 is made of a material weakly reflecting non-magnetic dielectric radar, low dielectric loss and equipped with real dielectric permittivity on the order of 3. This layer must favor the penetration of the radar wave in structure by impedance matching. Such a layer may consist of Nylon® fibers and a epoxy resin, for example.

La couche intermédiaire 4 est constituée par un matériau diélectrique non magnétique dont les pertes diélectriques sont plus importantes que celles de la couche externe 3, avec une permittivité diélectrique réelle de l'ordre de 5.The intermediate layer 4 consists of a non-magnetic dielectric material whose losses dielectrics are more important than those of the layer external 3, with a real dielectric permittivity of around 5.

La couche interne 5 est constituée par un matériau diélectrique non magnétique chargé de particules de carbone ayant une conductivité électrique importante, et conférant à ce matériau une absorption des ondes électromagnétiques plus importante que celles des deux premières couches. La permittivité diélectrique réelle de cette couche est plus importante, de l'ordre de 15 à 20.The inner layer 5 is made of a material non-magnetic dielectric charged with carbon particles having a high electrical conductivity, and conferring to this material absorption of electromagnetic waves more important than those of the first two layers. The actual dielectric permittivity of this layer is more important, of the order of 15 to 20.

Il est à noter qu'aucune de ces trois couches en elle-même n'est suffisamment absorbante pour donner à elle-seule et quelle que soit son épaisseur les performances d'absorption radar recherchées.It should be noted that none of these three layers in itself is not absorbent enough to give on its own and whatever its thickness performance radar absorption sought.

Le matériau 1 est complété de manière connue par une couche métallique 6 constituée par un film d'aluminium de l'ordre de 0,1 mm d'épaisseur, par exemple.The material 1 is completed in a known manner by a metal layer 6 consisting of an aluminum film on the order of 0.1 mm thick, for example.

Les couches 4 et 5 sont des composites fabriqués à base de résine époxy et de tissu de fibres de verre E.Layers 4 and 5 are composites made at based on epoxy resin and E glass fiber fabric

Il faut noter que le procédé d'obtention de ces trois couches est tout à fait classique et ne nécessite aucune adaptation du procédé classique de fabrication des matériaux composites structuraux. It should be noted that the process for obtaining these three layers is completely classic and does not require no adaptation of the conventional process for manufacturing structural composite materials.

Le matériau 1 selon l'invention peut avoir une épaisseur de l'ordre de 4 à 10 mm, avantageusement 6,75 mm environ. Les couches externe 3, intermédiaire 4 et interne 5 peuvent avoir respectivement une épaisseur de l'ordre de 1,5 à 4 mm, 0,5 à 2,5 mm et 1,5 à 3,5 mm. Avantageusement, ces trois couches ont des épaisseurs respectives de 2,75 mm, 1,5 mm et 2,5 mm.The material 1 according to the invention can have a thickness of the order of 4 to 10 mm, advantageously 6.75 mm approximately. The outer 3, intermediate 4 and internal 5 may have a thickness of 1.5 to 4 mm, 0.5 to 2.5 mm and 1.5 to 3.5 mm. Advantageously, these three layers have thicknesses 2.75 mm, 1.5 mm and 2.5 mm respectively.

Sur les figures 2 à 4, on a représenté graphiquement la variation du coefficient de réflexion en fonction de la fréquence. On constate que pour les trois bandes 8 à 18 GHz, 35 GHz et 94 GHz, on obtient une atténuation en réflexion supérieure à 13 dB. Cette performance d'atténuation est tout à fait satisfaisante dans le domaine d'utilisation visé.In Figures 2 to 4, there is shown graphically the variation of the reflection coefficient in frequency function. We note that for the three bands 8 to 18 GHz, 35 GHz and 94 GHz, we obtain a attenuation in reflection greater than 13 dB. This mitigation performance is quite satisfactory in the intended area of use.

Claims (8)

Matériau composite structural (1) apte à absorber des ondes radar de fréquences 8 à 18 GHz, 35 GHz et 94 GHz, caractérisé en ce qu'il comprend au moins trois couches (3,4,5) de matériaux diélectriques non magnétiques obtenues à partir d'un empilement de plis imprégnés : une couche externe (3) faiblement réflectrice et à faibles pertes ayant une permittivité diélectrique réelle de l'ordre de 3, pour favoriser la pénétration des ondes radar incidentes, une couche intermédiaire (4) ayant une permittivité diélectrique réelle de l'ordre de 5, et une couche interne (5) chargée de particules électriquement conductrices et ayant une permittivité diélectrique réelle importante de l'ordre de 15 à 20. Structural composite material (1) capable of absorbing radar waves of frequencies 8 to 18 GHz, 35 GHz and 94 GHz, characterized in that it comprises at least three layers (3,4,5) of non-magnetic dielectric materials obtained at from a stack of impregnated plies: a weakly reflecting and low loss outer layer (3) having a real dielectric permittivity of the order of 3, to promote the penetration of incident radar waves, an intermediate layer (4) having a real dielectric permittivity of the order of 5, and an internal layer (5) charged with electrically conductive particles and having a high real dielectric permittivity of the order of 15 to 20. Matériau composite structural selon la revendication 1, caractérisé en ce que les plis imprégnés sont des fibres de verre ou de Nylon® qui sont associées à des résines époxy.Structural composite material according to claim 1, characterized in that the impregnated pleats are glass or Nylon® fibers which are associated with epoxy resins. Matériau composite structural selon la revendication 2, caractérisé en ce qu'il présente une épaisseur de l'ordre de 4 à 10 mm.Structural composite material according to claim 2, characterized in that it has a thickness of the order of 4 to 10 mm. Matériau composite structural selon la revendication 3, caractérisé en ce que la couche externe (3) présente une épaisseur de l'ordre de 1,5 à 4 mm, la couche intermédiaire (4) une épaisseur de l'ordre de 0,5 à 2,5 mm, et la couche interne (5) une épaisseur de l'ordre de 1,5 à 3,5 mm.Structural composite material according to claim 3, characterized in that the outer layer (3) has a thickness of the order of 1.5 to 4 mm, the intermediate layer (4) a thickness of the order of 0.5 to 2.5 mm, and the internal layer (5) a thickness of the order from 1.5 to 3.5 mm. Matériau composite structural selon la revendication 4, caractérisé en ce qu'il présente une épaisseur de l'ordre de 6,75 mm, les couches externe (3), intermédiaire (4) et interne (5) ayant des épaisseurs respectives de 2,75 mm, 1,5 mm et 2,5 mm.Structural composite material according to claim 4, characterized in that it has a thickness of the order of 6.75 mm, the outer layers (3), intermediate (4) and internal (5) having thicknesses 2.75 mm, 1.5 mm and 2.5 mm respectively. Matériau composite structural selon l'une quelconque des revendications précédentes, caractérisé en ce que les particules électriquement conductrices sont des grains de carbone, ayant un diamètre inférieur à 0,1 mm, avec une proportion inférieure à 10 % en masse.Structural composite material according to one any of the preceding claims, characterized in what electrically conductive particles are carbon grains, having a diameter of less than 0.1 mm, with a proportion of less than 10% by mass. Utilisation du matériau composite tel que défini par l'une quelconque des revendications précédentes à la fabrication de parois pour véhicules blindés, dotées d'une résistance mécanique résistant à une pression de l'ordre de 1 tonne/cm2 et procurant une atténuation en réflexion des ondes radar supérieure à 10 dB.Use of the composite material as defined by any one of the preceding claims for the manufacture of walls for armored vehicles, endowed with a mechanical resistance resistant to a pressure of the order of 1 ton / cm 2 and providing attenuation in reflection radar waves greater than 10 dB. Utilisation selon la revendication 7 pour la réalisation de coffres de servitude ou de protection pour des véhicules blindés.Use according to claim 7 for the production of easement or protection boxes for armored vehicles.
EP98402984A 1997-12-11 1998-11-30 Composite radar absorbing material and use of such a material Expired - Lifetime EP0924798B1 (en)

Applications Claiming Priority (2)

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FR9715681 1997-12-11
FR9715681A FR2772520B1 (en) 1997-12-11 1997-12-11 RADAR WAVE ABSORBING COMPOSITE MATERIAL AND USE OF SUCH MATERIAL

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EP0924798A1 true EP0924798A1 (en) 1999-06-23
EP0924798B1 EP0924798B1 (en) 2005-01-26

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US (1) US6111534A (en)
EP (1) EP0924798B1 (en)
AT (1) ATE288139T1 (en)
CA (1) CA2254314C (en)
DE (1) DE69828759T2 (en)
ES (1) ES2232924T3 (en)
FR (1) FR2772520B1 (en)

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CN104763099B (en) * 2015-03-06 2017-07-07 中国人民解放军国防科学技术大学 Big plate of shelter with radar invisible function and preparation method thereof
US10697856B2 (en) 2016-07-08 2020-06-30 Dynamic Research Inc. To a soft collision partner (aka soft car) used in system for testing crash avoidance technologies
CN111516340B (en) * 2020-07-03 2020-09-22 宁波曙翔新材料股份有限公司 Invisible and anti-damage shielding material and preparation method thereof

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CN105383130A (en) * 2014-12-15 2016-03-09 沈阳航空航天大学 Method for functionally modifying composite material laminated board by radar absorbing nano-membrane

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FR2772520A1 (en) 1999-06-18
FR2772520B1 (en) 2000-01-14
CA2254314A1 (en) 1999-06-11
US6111534A (en) 2000-08-29
DE69828759T2 (en) 2006-05-18
DE69828759D1 (en) 2005-03-03
EP0924798B1 (en) 2005-01-26
CA2254314C (en) 2006-08-08
ATE288139T1 (en) 2005-02-15
ES2232924T3 (en) 2005-06-01

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