FR2826188A1 - Stealth coating for military aircraft, vehicles and ships, consists of an elastomer matrix or matrices comprising a dielectric filler and a ferromagnetic filler - Google Patents

Abstract

A stealth coating comprising components capable of modifying the spectral characteristics of a material which consists of at least one matrix comprising a dielectric filler and ferromagnetic filler such as ferrite The matrix is of elastomers such as silicone, preferably an alkyde/silicone or polyvinylchloride varnish. The ferromagnetic fillers are polygonal ferrites or conductive polymers such as polyaniline, polypyrrole or polyalkylthiophene. The coating has a thickness of one quarter of the wavelength of the masked (incident detection) radiation or illuminator striking the surface. It may consist of a single multifunctional layer or of several specialized monofunctional layers. It may consist of a first layer comprising infrared signature reduction components and an exterior layer transparent to infrared and comprising electromagnetic laser type signature reduction components or of a layer comprising electromagnetic radar signature reduction components and an outer non-interacting layer comprising infrared signature reduction components or be a homogenous matrix comprising infrared and radar signature reduction components. It may further comprise on its surface a specialized CML 106 (Counter Measure Laser) layer and optically active molecules with aromatic cores and optically active crystals of the photo and/or electro and/or thermoluminescent type.

Description

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MULTIFUNCTIONAL MATERIALS WITH CONTROLLED THERMOOPTIC EFFECTS
The present invention relates to the field of materials intended to reduce the electromagnetic and optical signature of particularly military devices.

 South African patent ZA972655 discloses a fluid material absorbing radiation. It is composed of a light particulate material, the light articular material consisting of separate particles, each particle being coated with a coating material associated with an electrically conductive material. The coating material may be electrically conductive and / or the coating material may be mixed with an electrically conductive material.

 FR2720194 French patent describes an ionizable paint coating applied to the outer surface of the body of the part and an electrically conductive layer is disposed on the inner surface of said body.

 FR2716038 French patent describes a camouflage method of a machine against the detection by electromagnetic means in the optical wavelength bands of covering the greater part at least of the emitting surfaces of said machine with a coating comprising at least one material inherently having a selective emittance.

 These different solutions are effective only in relation to a type of detection, and do not simultaneously reduce the risks corresponding to different electromagnetic threats.

 The object of the present invention is to propose an extended solution for reducing and / or modifying the electromagnetic signatures of the potential targets of the battlefield in an enlarged manner.

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 For this purpose, the invention relates, in its most general sense, to an intrinsically stealth coating in several wavelength bands comprising organic or inorganic components capable of modifying the spectral characteristics, the spectral response of these coatings, of these stealth materials. , characterized in that they consist of at least one matrix, in particular an organic matrix, comprising dielectric charges such as certain sulphides and ferromagnetic charges such as ferrite.

 Preferably, the matrix consists of elastomers such as silicone resins.

 Advantageously, the coating has a thickness corresponding to a quarter of the wavelength of the illuminating radiation striking the surface. Coatings of this type consist of matrices whose spectral responses interact with the electromagnetic flows of the battlefield threats to absorb them, modify them, shift the frequencies according to the laws of Stokes. These controlled thermooptic materials do not comply with Planck's law.

 According to one variant, these materials consist of a homogeneous multifunctional matrix.

 According to another variant, these materials are constituted by a plurality of layers. the spectral response of each of them corresponds to an electromagnetic threat.

 According to a particular embodiment, the ferromagnetic charges are polygonal type ferrites.

 According to one variant, the ferromagnetic charges are conductive polymers of polyaniline, polypyrolle or polyalkylthiophene type.

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According to a first variant, the coating consists of a first layer comprising infrared signature reduction components (IRS) and a transparent outer layer in the infrared and comprising components for reducing the electromagnetic signature LASER in order to also reduce the
Equivalent laser surface rated SEL.

According to a second variant, it consists of a first layer comprising components for reducing the electromagnetic signature Radar noted
RAM (Radar Absorption Material), and by a non-interacting layer comprising infrared signature reduction components denoted SIR.

 According to a third variant, it consists of a homogeneous matrix comprising SIR infrared signature reduction components and RAM Radar signature reduction components.

The present invention will be better understood on reading the description of a nonlimiting example of embodiment which follows, with reference to the appended drawings in which: FIG. 1 represents the detection wavelength bands. Figures 2 to 4 describe different possible architectures of multilayer materials
The invention aims at conferring on an airborne, land or naval craft intrinsic qualities of discretion compared to most known detection equipment, in particular a INFRA-RED and / or RADAR discretion, and / or LASER by the affixing of homogeneous or laminated multifunction liners on said machines or on camouflage tarpaulins for the protected persons. On the tarpaulin support, the stealth materials as described in the invention may be applied by spraying or coating.

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 Stealth materials as described in this patent may also be added to other radar discretion systems obtained by the forms of facilities or mobiles to protect. This geometric type technique, simple in principle, has disadvantages because the shapes imposed for good radar efficiency may be incompatible with the optimum characteristics of the mobile. This type of protection, on the other hand, is not too restrictive for ships, land vehicles or fixed infrastructures. Radar discretion may be diminished in the case of multistatic radar. A good approach may be to reduce or modify the geometry of surface discontinuities (inspection hatches, junction points of moving parts on the aircraft's cell) by various solutions such as sails with variable camber, isoic junctions, beveling fins and flaps, negative dihedrons, armament in the hold. It is obvious that during an attack, with the bunkers open, the aircraft is no longer stealthy. Similarly no electromagnetic transmission must be made to avoid indiscretion.

 The invention consists in introducing into the SIR, SEL, RAM coatings, crystalline active substances, of optically active crystals type COA or organic of optically active molecules type denoted MOA. In addition, the SA active substances included in the RAM materials are either hexagonal, cubic or spinel or even chiral ferrites, or conductive polymers of polyaniline, polypyrolle or polyalkylthiophene type.

atmosphériques appelées respectivement bande II (3-5um) et Bande III (8-12 um), la Bande I (l, 5-2, 5um) n'étant plus The infrared discretion is mainly in the 2 transmission windows

called Band II (3-5um) and Band III (8-12 um), Band I (1,5-2,5um) being no longer

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 currently exploited. Band II is mainly used by missile searchers while band III is more specifically dedicated to thermal imaging cameras for detection and identification. This differentiation tends to disappear with bi-band autodirectors whether they are imagers or not.

Infrared discretion is usually and mainly conferred by low emittance conductive materials (Al alloys of different geometries and particle sizes) that are introduced into protective varnish type materials or paints. These materials, gray-type cops meet the law of Planck. They are quite economical to use but have two major drawbacks for the future:
Possibility of reconstructing the temperature map of the observed object by spectral analysis. (Emission peak um = F (8)).

 If the conductive active substances are too concentrated in the matrix to have a low emittance, this IR material can not be associated with a RAM material because it increases the overall RES.

 The coatings according to the invention fulfill several functions simultaneously and are adapted to the appearance of new threats such as the simultaneous dual-mode missile whose development is expected in the short term (ex MICA air-to-air missile). It is obvious that the coupling of several functions depends on the mission profiles for which weapons systems are planned. In fact, a ground support aircraft will need different treatments from an air superiority plane, an armored vehicle or a ship. Some target areas require only SIR reduction therapy, or SER reduction therapy, while other areas require SER-SIR-SEL combination therapy.

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 Currently IR materials are conductive materials except for some non-planckian dielectric-type SIR reduction materials developed by the authors. While the current RAM materials are essentially dielectric or conductive with particular architectures difficult to master during their application.

 Figures 2 to 4 describe different possible architectures of multifunctional materials. The SIR layer is a silicone resin doped with thermochromic materials, Ytrium oxides (Eu ") and Zn metal sulphides for example, with a particle size of 1.5 to 10 μm for a deposition thickness of 10 to 50 μm, for example. There is a correlation between these different parameters that satisfy Mie's theory and Bert-Lambert's law.

 The SIR and SER reduction functions can also be combined with the SEL reduction functions as well as the visible camouflage according to NATO or GAM standards. French C (Figures 5 and 6).

 FIG. 4 presents a multifunctional material with a homogeneous structure in which the active RAM and IR centers defined in the present BVT are mixed in the matrix and do not disturb the intrinsic characteristics of the SER and SIR stealth coatings, or improve their characteristics.

 To achieve this goal, particular attention will be paid to the concentration of SA (Active Substances), COA (Optically Active Crystals) or MOA (Optically Active Molecules) and to the interaction of these particles with one another. saturation, and self quenching as indicated in the standard formulas below.

 The systems of discretion and stealth, the technologies and formulas that are the subject of the present invention form a new generation of materials.

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multi-function "with movement of bands with controlled thermooptic effects, in the following different wavelength ranges: - R, decrease of the SIR-Signature Infra
Red-Bands II and III, (3/5 and 8 / 12un) - SEL (CML 1. 06) - Measuring Laser-rangefinder or illuminator, 1, 06/1, 54um,
RAM, decrease of SER-Signature
Equivalent Radar-, in the 4/18 domain
Ghz, (ie)
On the other hand, these "band moving" materials are intrinsically compatible with each other and allow multiple battlefield electromagnetic threats to be taken into account simultaneously by developing combined protection (stealth, deception or camouflage) for potential targets or targets. , in particular in the following fields: - IR / RAM, - IR / LASER, - IR / RAM / LASER In the development of the above-mentioned formulas, the visible and near-IR colorimetric components are defined by the GAM C or NATO standards.

 The results in this field of IR Frequency are given with respect to the emissivity of the black body: e = 1.

It should be noted that GAM C (Fr.) or NATO standardized military paints and coatings are given for: e == 0. 85 / 0.9 depending on the camouflage hues.

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I INFRA RED

<Tb>
<tb> I <SEP> A <SEP>: <SEP> Materials <SEP> SIR <SEP> type <SEP> IR / B2 <SEP> (3-5jam) <SEP> White <SEP> GAM. <SEP> C
<tb> Type <SEP> Matrices <SEP> S. <SEP> A. <SEP> / COA / MOA <SEP> Thickness <SEP> Color <SEP> Results
<tb> IR / B2Silicone + ZnS <SEP> (Cu / Ag) <SEP> 100m <SEP> White <SEP># = 0. <SEP> 36
<tb> CAF <SEP> 3
<tb> Toluene <SEP> + Y203 <SEP> (Eu ++)
<tb> + ZnS <SEP> (C26H27N207CI.)
<tb> I <SEP> B <SEP>: <SEP> Materials <SEP> SIR <SEP> type <SEP> IR <SEP> BII <SEP> Green <SEP> NATO
<tb> Type <SEP> Matrices <SEP> SA / COA / MOA <SEP> Thickness <SEP> Color <SEP> Results
<tb> IR / B2 <SEP> Silicone / + ZnS <SEP> (Cu / Ag) <SEP> 75um <SEP> Green <SEP> t = 0. <SEP> 54
<tb> Alkyd <SEP> + Y203 <SEP> (Eu ++)
<tb> DCE <SEP> + CrO <SEP> type <SEP> GX
<tb> + Blue <SEP> Phthalocyanine
<tb> + Yellow <SEP> 3G <SEP> Thiosol
<tb> + Ti02 <SEP> type <SEP> RC2R
<tb> + Violet <SEP> Solanthrene
<tb> + Fe203 <SEP> Yellow <SEP> 920
<tb> I <SEP> C <SEP>: <SEP> Materials <SEP> SIR <SEP> type <SEP> IRBII <SEP> sand <SEP> GAMC
<tb> Type <SEP> Matrices <SEP> S. <SEP> A./COA/MOA <SEP> Thickness <SEP> Color <SEP> Results
<tb> Silicone / + ZnS <SEP> (Cu / Ag) <SEP> 75 m <SEP> Sand1 <SEP># = 0. <SEP> 46
<tb> IR / B2 <SEP> Alkyd <SEP> + Y203 <SEP> (Eu ++)
<tb> DCE <SEP> + ZnS <SEP> (C28H31N203Cl.)
<tb> + Fe203 <SEP> treated <SEP> to <SEP> 5030K
<tb> + Cr02
<tb> + Violet <SEP> Solanthrene
<tb> + Ti02
<tb> + Yellow <SEP> mineral
<Tb>

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<Tb>
<tb> I <SEP> D <SEP>: <SEP> Materials <SEP> SIR <SEP> type <SEP> IR <SEP> BII / IRBIII <SEP> Gray <SEP> aeronautical
<tb> Type <SEP> Matrices <SEP> S. <SEP> A./COA/MOA <SEP> Thickness <SEP> Color <SEP> Results
<tb> Silicone <SEP> + ZnS <SEP> (Cu / Ag) <SEP> 60). <SEP> lm <SEP> GrayAe <SEP> s = 0. <SEP> 45 / B2
<tb> IR / B2 <SEP> + Y203 <SEP> (Eu ++) <SEP> S = 0. <SEP> 65 / B3
<tb> IR / B3 <SEP> + Al <SEP> (lenticular)
<tb> + Bentone
<tb> + Red <SEP> Monoazoic
<tb> + Yellow <SEP> Rh. <SEP> (C3H3NOS2)
<tb> + Blue <SEP> Phthalocyanine
<Tb>

In this formula ID, the desired colorimetry is obtained by combining non-conductive organic or inorganic pigments of complementary colors, which makes it possible to avoid the use of metal pigments, oxides for example, which can impair the performance of IR and RAM stealth. multifunctional materials.

II Countermeasure LASER telemetry or illuminator
The results in the LASER wavelength ranges, l, 06um in the example, are given in dB measuring the attenuation of the reference beam emitted by the rangefinder or the illuminator. The measurements were performed with a TM 18 rangefinder operational.

II A: SML materials CML type l, 06um

<Tb>
<tb> Type <SEP> Matrix <SEP> SA / MOA / COA <SEP> Thickness <SEP> Color <SEP> Results
<tb> CML1. <SEP> 06 m <SEP> PVC <SEP> crosslinked <SEP> + C40H30S204C12 <SEP> 75um <SEP> (-19dB)
<tb> Solvent <SEP>: <SEP> Heptamétinecyanine <SEP> Transluce
<tb> dichloroethane <SEP> + C15H11NO
<tb> PFO
<tb> (dipheniloxazol)
<tb> + C24H16N202
<tb> POPOP <SEP> (5-Phenyloxa
<tb> zol)
<Tb>

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III Contre-mesure LASER/IRBII/IRBIII III A : Matériaux SEL/SIR de type CML 1, 06/IR (3-5/8-12um)

III Countermeasure LASER / IRBII / IRBIII III A: SEL / SIR materials of type CML 1, 06 / IR (3-5 / 8-12um)

<Tb>
<tb> Type <SEP> Matrices <SEP> SA / MOA / COA <SEP> Thickness <SEP> Color <SEP> Results
<tb> CML1. <SEP> 06 <SEP> said <SEP> A <SEP> said <SEP> A <SEP> said <SEP> II <SEP> A <SEP> said <SEP> I <SEP> A <SEP> (-19dB )
<tb> IRBII <SEP> a <SEP> A <SEP> A <SEP > (E <SEP>: <SEP> = <SEP> 0. <SEP> 3 <SEP> 6)
<tb> IRBIII """"<SEP> (e = 0. <SEP> 73)
<Tb>

It should be noted that the type materials
CML1.06 are IRBII-IR transparent and semi-transparent in IR III band allowing an association with infrared active materials for SIR as described in IA / B / C / D.

IV INFRA RED and RADAR
SIR materials of the dielectric type, such as those described herein, do not interfere with the operation of the RAM (Radar Absorption Materials) materials to which they are applied. On the contrary, they improve the efficiency of the order of 5 to 10%.

 IV A: Multifunctional multiband materials of SIR / RAM laminated type.

 These materials according to the invention are applied to a JAUMANN screen-type RAM material comprising a succession of conductive and dielectric layers, particularly suitable for HF 4 / 8Ghz and 12 / 18Ghz bands.

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<Tb>
<tb> Type <SEP> Matrices <SEP> SA / MOA / COA <SEP> Bands <SEP> Results
<tb> IR / RAM <SEP> If <SEP> RTV <SEP> 4P <SEP> Rp <SEP> + ZnS <SEP> (Ca, <SEP> Mg) <SEP> 4/10 <SEP> Ghz <SEP > A% <SEP> = 20dB
<tb> (Laminate) <SEP> Primary <SEP> MB <SEP> + Y203 <SEP> (Eu ++)
<tb> DCE
<tb> + ZnS <SEP> (C32H31N2O7Cl) <SEP> 10 / 20Ghz <SEP> A% = 15dB
<tb> + Red <SEP> monoazo <SEP> IRBII <SEP> (3 / 5m) <SEP> g = <SEP> 0. <SEP> 45
<tb> + Yellow
<tb> Rh <SEP> (C3H3NOS2)
<tb> + Blue
<tb> Phthalocyanine
<tb> + Bentone
<Tb>
IV B: Multi-function SIR / RAM multi-function materials with homogeneous matrix

<Tb>
<tb> Type <SEP> Matrices <SEP> SA / MOA / COA <SEP> Thickness <SEP> Color
<tb> IR / RAM <SEP> Elastomer <SEP> If <SEP> + BaMe2Fe019 <SEP> (hex) <SEP> 4mm <SEP> Gray <SEP> Bridge
<tb> (Homogeneous) <SEP> RTV <SEQ> 4P <SEP> Rp. <SEP> + ZnS <SEP> (Ag) <SEP> (Cu)
<tb> + Y203 <SEP> (Eu ++)
<tb> + Colorimetry
<tb> Organic
<Tb>

Note: The characteristics of these electromagnetic materials with controlled thermooptic effects can be modified by varying the concentrations of the doping SAs of the formulas described. These different materials, compatible with each other, can be combined into specialized layers, homogeneous matrices or a combination of these combinations.

 According to a possibility offered by the invention, the coating will also comprise, on the surface, a specialized layer of CML 106 (Counter Laser Measurement).

 Furthermore, according to one embodiment of the invention, the coating will comprise optically active cyclic aromatic ring molecules and optically active crystals of the photo and / or electro and / or thermoluminescent type. In the same way, one of the matrices forming the coating may be constituted by a varnish of Alkyde / Silicone or PVC type.

Claims (11)

1-stealth coating comprising components capable of modifying the spectral characteristics of a material, characterized in that it consists of at least one matrix comprising a dielectric charge and a ferromagnetic charge such as ferrite.  2-stealth coating according to claim 1, characterized in that the matrix consists of elastomers such as silicone.  3-stealth coating according to claim 1 or 2, characterized in that it has a thickness corresponding to a quarter of the wavelength of radiation (incident detection) masked, illuminator striking the surface.  4-stealth coating according to any one of the preceding claims, characterized in that it is constituted by a plurality of specialized monofunction strata or a single multifunctional homogeneous layer.  5-stealth coating according to any one of the preceding claims, characterized in that the ferromagnetic charges are polygonal type ferrites for example.  6-stealth coating according to any one of the preceding claims, characterized in that the ferromagnetic charges are conducting polymers of polyaniline, polypyrolle or polyalkylthiophene type. <Desc / Clms Page number 13>  7-stealth coating according to any one of the preceding claims, characterized in that it consists of a first layer comprising infrared signature reduction components and an infrared transparent outer layer and comprising Electromagnetic signature reduction components of the laser type.  8-stealth coating according to any one of claims 1 to 6, characterized in that it consists of a first layer comprising radar electromagnetic signature reduction components and by a layer that does not interact and comprising components reduction of the infra-red signature.  9-Stealth coating according to any one of the preceding claims, characterized in that it consists of a homogeneous matrix comprising infrared signature reduction components and radar electromagnetic signature reduction components.  10-coating according to any one of the preceding claims, characterized in that it further comprises, on the surface, a specialized layer of CML 106 (Counter Laser Measurement).  The coating according to any one of the preceding claims, characterized in that it furthermore comprises optically active molecules with aromatic cyclic rings and optically active crystals of the photo and / or electro and / or thermoluminescent type. <Desc / Clms Page number 14>  12-stealth coating according to claims 1 and 2 characterized in that one of the matrices consists of a varnish of Alkyde / Silicone or PVC type.