EP3701214B1 - Use of material for masking a target and ammunition for dispersing such a masking material - Google Patents

Use of material for masking a target and ammunition for dispersing such a masking material Download PDF

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Publication number
EP3701214B1
EP3701214B1 EP18779054.8A EP18779054A EP3701214B1 EP 3701214 B1 EP3701214 B1 EP 3701214B1 EP 18779054 A EP18779054 A EP 18779054A EP 3701214 B1 EP3701214 B1 EP 3701214B1
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EP
European Patent Office
Prior art keywords
masking
ammunition
rod
ammunition according
dispersion
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EP18779054.8A
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German (de)
French (fr)
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EP3701214A1 (en
Inventor
Nicolas Perrot
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Mecar SA
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Mecar SA
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Priority to SI201830690T priority Critical patent/SI3701214T1/en
Priority to RS20220745A priority patent/RS63479B1/en
Priority to HRP20221002TT priority patent/HRP20221002T1/en
Publication of EP3701214A1 publication Critical patent/EP3701214A1/en
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Publication of EP3701214B1 publication Critical patent/EP3701214B1/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F41—WEAPONS
    • F41H—ARMOUR; ARMOURED TURRETS; ARMOURED OR ARMED VEHICLES; MEANS OF ATTACK OR DEFENCE, e.g. CAMOUFLAGE, IN GENERAL
    • F41H9/00—Equipment for attack or defence by spreading flame, gas or smoke or leurres; Chemical warfare equipment
    • F41H9/06—Apparatus for generating artificial fog or smoke screens
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F41—WEAPONS
    • F41H—ARMOUR; ARMOURED TURRETS; ARMOURED OR ARMED VEHICLES; MEANS OF ATTACK OR DEFENCE, e.g. CAMOUFLAGE, IN GENERAL
    • F41H3/00—Camouflage, i.e. means or methods for concealment or disguise
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
    • F42B12/00—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material
    • F42B12/02—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material characterised by the warhead or the intended effect
    • F42B12/36—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material characterised by the warhead or the intended effect for dispensing materials; for producing chemical or physical reaction; for signalling ; for transmitting information
    • F42B12/46—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material characterised by the warhead or the intended effect for dispensing materials; for producing chemical or physical reaction; for signalling ; for transmitting information for dispensing gases, vapours, powders or chemically-reactive substances
    • F42B12/48—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material characterised by the warhead or the intended effect for dispensing materials; for producing chemical or physical reaction; for signalling ; for transmitting information for dispensing gases, vapours, powders or chemically-reactive substances smoke-producing, e.g. infrared clouds
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
    • F42B12/00—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material
    • F42B12/02—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material characterised by the warhead or the intended effect
    • F42B12/36—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material characterised by the warhead or the intended effect for dispensing materials; for producing chemical or physical reaction; for signalling ; for transmitting information
    • F42B12/56—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material characterised by the warhead or the intended effect for dispensing materials; for producing chemical or physical reaction; for signalling ; for transmitting information for dispensing discrete solid bodies
    • F42B12/70—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material characterised by the warhead or the intended effect for dispensing materials; for producing chemical or physical reaction; for signalling ; for transmitting information for dispensing discrete solid bodies for dispensing radar chaff or infrared material
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
    • F42B33/00—Manufacture of ammunition; Dismantling of ammunition; Apparatus therefor

Definitions

  • the technical field of the invention is that of materials making it possible to ensure the masking of an objective.
  • Masking materials are well known in the military field. They make it possible to protect an objective, for example a vehicle, by preventing its detection by an enemy means.
  • Dispersed using a projectile they also make it possible to create a masking cloud in an area, thus allowing the progression of vehicles or infantry towards said area, sheltered from the cloud.
  • the infrared domains which it is more particularly necessary to mask from an operational point of view is the 8-14 micrometer band.
  • silica powder (patent DE4126016 ), titanium dioxide (statutory invention registration USH769), calcium or magnesium carbonate (patent FR2396265 ), carbon powder or carbon nanotubes (patents FR2730742 and FR2421363 ).
  • the materials forming clouds of droplets have the disadvantage of being very corrosive and of forming clouds that are both corrosive and toxic, generally comprising hydrochloric acid. They are most often discarded in favor of the dispersion of inert materials.
  • Metallic powders are interesting but the mass of the block of powder necessary to achieve a masking of relatively large dimensions (height or width greater than 5 meters) will greatly increase the weight of the ammunition responsible for dispersing the material, which can lead to destabilization of the projectile in flight.
  • the metallic material can also become compacted during storage of the ammunition, leading to masking performances different from those initially expected and can possibly destabilize the projectile in flight by a displacement of the center of gravity.
  • the masking obtained to be able to have a certain duration, it is necessary for the grains of the material to have a sufficiently reduced rate of descent.
  • the object of the invention is therefore to propose a material of reduced mass and having good masking efficiency with respect to electromagnetic radiation in a given range of wavelengths.
  • the invention thus allows masking in the visible range but also advantageously in the infrared range, in particular in the 3-5 and 8-14 micrometer ranges.
  • the material according to the invention according to claim 1 is of simple industrial implementation and does not present any risk of use.
  • This material is in particular compatible with European REACH regulations.
  • the invention also proposes a masking ammunition according to claim 6 implementing such a material and allowing its optimal dispersion on the ground.
  • the subject of the invention is an ammunition according to claim 6 using aluminum oxy-hydroxide, such as boehmite or pseudo-boehmite, as masking material dispersible by ammunition to ensure the masking of a target with respect to electromagnetic radiation in a given range of wavelengths.
  • aluminum oxy-hydroxide such as boehmite or pseudo-boehmite
  • the invention proposes a use in which masking is sought for ranges of infrared wavelengths, the particle size of the oxy-hydroxide of aluminum then being between 1 and 100 micrometers, with at least 90% of the grains of the material having an average diameter of between 25 and 45 micrometers.
  • the invention also relates to ammunition comprising a masking material intended to be dispersed by ammunition to produce a cloud ensuring the masking of an objective vis-à-vis electromagnetic radiation in a given range of wavelengths, material characterized in that it comprises at least one aluminum oxy-hydroxide, such as boehmite or pseudo-boehmite.
  • this ammunition is effective in a range of infrared wavelengths and the aluminum oxy-hydroxide has a particle size between 1 and 100 micrometers with at least 90% of the grains of the material having an average diameter between 25 and 45 micrometers.
  • the aluminum oxy-hydroxide may be coated with a binder.
  • the binder may in particular comprise polyvinyl alcohol (PVA).
  • PVA polyvinyl alcohol
  • the invention finally relates to a masking ammunition comprising a casing containing a masking material and a pyrotechnic dispersion charge which can be actuated by a rocket, ammunition characterized in that the masking material comprises at least one oxy-hydroxide of aluminum, such as boehmite or pseudo boehmite.
  • the dispersal charge consists of at least one explosive material placed in a metallic dispersion rod closed at its end remote from the fuze, the rod extending axially into the masking material in a manner coaxial with the axis of the munition.
  • the masking material may comprise at least one block compressed directly inside the envelope and around the dispersion rod.
  • the masking material can be compressed inside the envelope without using a binder.
  • Boehmite and pseudo boehmite are aluminum oxy-hydroxides with the generic formula AlO(OH).
  • Boehmite is a material that occurs naturally in bauxite ore. It is a hydrated alumina having a lamellar orthorhombic crystal structure.
  • Pseudo boehmite is a common designation for a finely crystallized boehmite, containing more water than boehmite, and formed of octahedral crystalline layers separated by water molecules.
  • boehmite and more particularly finely crystallized boehmite or pseudo boehmite, can be dispersed in the air in the form of a cloud and that the clouds thus produced have a certain durability favoring a masking of a target, for example in the visible domain.
  • the falling velocity of the cloud particles was relatively slow with falling velocities of less than 1 m/s.
  • Such behavior is due, on the one hand, to the reduced mass of the material, the average density of the material itself of which is of the order of 3 to 3.07, and the bulk density of the uncompacted bulk powder of which is less than 1.5, and is due on the other hand to the fineness of the boehmite crystals which are morphologically in the form of plates or sheets as illustrated in the microscopic photo of figure la, or even in the form of spheres carrying a median hollow as represented in the figure 1b ).
  • the powder of the material has many advantages.
  • this powder is not a material listed in a pyrotechnic risk class.
  • the loading of the ammunition can be carried out in bulk or by compression, however the masking performance of a compressed load will be better.
  • the loading by compression will be carried out by implementing conventional and inexpensive installations, such as a hydraulic press.
  • the latter is inert, unlike powdered aluminium.
  • the bulk density of the bulk powder is less than 1.5, so the material is particularly light.
  • the cloud generated by the suspension of this powder is not corrosive and it is very slightly toxic for humans and the environment.
  • the generated cloud ensures masking in the infrared ranges of 3 to 5 and 8 to 14 micrometers and in the visible spectrum.
  • the masking is mainly ensured by absorption of the radiation.
  • Air humidity or oxygen levels have little influence on the effectiveness of the aerosol.
  • the powder does not react, neither with the air nor with the water in the atmosphere.
  • Boehmite powder or pseudo boehmite is commercially available for different types of grain sizes.
  • This powder is generally produced by a conventional method of the sol-gel type comprising a step of hydrolysis and condensation of an aluminum alkoxide with an excess of water to form an aluminum hydroxide, a step of redissolution of the precipitate obtained to form the Sol then formation of the Gel by drying of the Sol.
  • boehmite or pseudo boehmite grains can be modified by implementing a spray drying tower.
  • a spray drying tower makes it possible to ensure drying of the industrial boehmite or pseudo-boehmite gel solutions while making it possible to calibrate the desired particle size.
  • Atomization towers are well known in the field of industrial processes for the production of powdery materials and it is therefore not necessary to describe them in more detail.
  • This atomization tower will be parameterized so as to obtain a powder whose particle size at d(0.9) is between 25 and 35 micrometers, that is to say that 90% of the grains of the material have an average diameter of between 25 and 35 micrometers, the overall particle size of the grains being further distributed between 1 micrometer and 100 micrometers.
  • increasing the atomization pressure makes it possible to reduce the size of the grains of the powder.
  • Such a choice of particle size leads to grains G1, G2 in the shape of spheres carrying a median hollow G3 as represented in the figure 1b ).
  • This particle size also provides masking in the infrared wavelength ranges in the bands of 3 to 5 and 8 to 14 micrometers.
  • the aluminum oxy-hydroxide grains could be coated with a binder.
  • Such a variant will make it possible to increase the size of the granules formed and will facilitate their subsequent compaction in ammunition. It also makes it possible to limit the dispersion of the grains of the material during the manufacturing stages, in particular by limiting the level of dust.
  • the binder may for example comprise polyvinyl alcohol (PVA) in a proportion of 1% to 4% by mass.
  • PVA polyvinyl alcohol
  • the binder is incorporated into the solution of the aluminum oxy-hydroxide grains in water and before atomization.
  • the figure 2 shows in longitudinal section an example of an embodiment of a masking ammunition 1 according to the invention, the ammunition having a conventional shape of a projectile with an axis of rotational symmetry X-X'.
  • This ammunition is intended to be fired by a weapon system not shown in the direction of an area of land. Its function is to generate an infrared or visible masking cloud at said zone.
  • the ammunition 1 comprises an envelope 2 containing a masking material 3 and a pyrotechnic dispersion charge 4 which can be actuated by a rocket 5, for example of the type chronometer capable of dissipating a flame in the axial direction X-X'.
  • the casing carries at its rear part a belt 12 allowing in a conventional way to ensure gas tightness during firing in the barrel of a weapon.
  • the dispersion charge 4 consists of at least one explosive material, for example tablets of an explosive combining hexogen and wax or of a composite explosive, which is placed in a metal dispersion rod 6 closed at its end 6a away from the rocket.
  • the rod 6 is integral with a connecting ring 7 which is fixed to the casing 2, for example by a thread 8.
  • the rod 6 extends axially in the masking material 3 in the direction of the axis X-X' of ammunition 1.
  • the connecting ring 7 is preferably made in one piece with the rod 6. This assembly will for example be made of aluminum to reduce the mass of the ammunition.
  • the connecting ring 7 contains an internal housing 9 which receives a detonation relay 10 and which is in communication with the cavity of the rod 4. It also comprises a thread 11 allowing the fuse 5 to be fixed.
  • the quantity of explosive in the dispersal charge 4 is defined as sufficient to ensure the rupture, both of the rod 6 and of the casing 2 of the ammunition.
  • the fuse 5 When the ammunition is launched by a cannon, for example to mask a target, at a given instant on the trajectory of the ammunition or by the impact of the ammunition, the fuse 5 causes the initiation of the detonation relay 10 which itself initiates the dispersal charge 4.
  • the bursting of the dispersion charge 4 stresses the masking material 3 which causes the bursting of the casing 2 of the ammunition and the dispersion of the masking material 3.
  • the rod 6 In order to improve the distribution of the masking cloud, the rod 6 will be given a length such that there remains behind the rod 6 a distance D, at least equal to half the internal diameter d of the envelope 2. such an arrangement makes it possible to avoid reducing the density of the masking cloud at its center. A rod 6 that is too long runs the risk of creating an annular cloud.
  • the masking material 3 is a material essentially comprising aluminum oxy-hydroxide, such as boehmite or pseudo-boehmite, the grains of which are optionally coated with a binder such as polyvinyl alcohol (PVA).
  • a binder such as polyvinyl alcohol (PVA).
  • the material 3 is placed in the envelope 2 by compression directly in the envelope. At least one compressed block is thus produced directly inside the casing 2 and around the dispersion rod 6.
  • the casing 2 carries the connecting ring 7 extended by the cane 6. It is easy with the aid of a piston pierced to the diameter of the cane 6 to carry out an in situ compression of the masking material 3, without it being necessary to carry out subsequent machining of the compressed block to allow the passage of the rod 6. This results in a great ease of manufacture of the ammunition 1.
  • the compression may be carried out in one or more passes depending on the length of the ammunition 1.
  • Wedging washers 13 will be positioned between the rear of the block of masking material 3 and a cap 14 ensuring the closure of the envelope 2 at its rear part.
  • the washers are used to compensate for manufacturing tolerances on the length of the compressed block of masking material 3 so that the block is well immobilized axially in the ammunition 1.
  • dispersion charge 4 can only be put in place after the masking material 3 has been loaded.
  • the masking material 3 compression operations are therefore carried out on a completely inert ammunition 1.
  • the masking material 3 can be compressed inside the casing 2 without using a binder.
  • a solvent will be added to the masking material, for example methyl ethyl ketone in a reduced proportion (5% to 20% by mass, to limit dust.
  • the solvent may or may not be evacuated by drying with suction before setting up the base 14.
  • the tests carried out made it possible to verify that the masking material 3 according to the invention compressed easily, even without a binder.
  • the block obtained is particularly compact and solid. No risk of dislocation during firing is to be feared. No settling of the masking material during the storage phases is to be feared either.
  • the powder of the masking material can be compressed in a separate mold to form a compressed block which can be manipulated to introduce it into the envelope 2.
  • the energy communicated by the dispersion charge 4 during its initiation is sufficient to fragment the block of masking material which, outside the envelope 2, becomes a powdery material forming the desired masking cloud and with the expected performance, especially in the infrared range.
  • ammunition 1 according to the invention which is not fired by a cannon or a mortar tube but which equips the launcher tubes of the close defense ammunition of armored vehicles.
  • the masking cloud will have the effect of concealing the vehicle which fires the ammunition according to the invention.
  • the aluminum oxy-hydroxide as masking material 3 does not necessarily have to be in the form of boehmite or pseudo-boehmite.

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  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Manufacturing & Machinery (AREA)
  • Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
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Description

Le domaine technique de l'invention est celui des matériaux permettant d'assurer le masquage d'un objectif.The technical field of the invention is that of materials making it possible to ensure the masking of an objective.

Les matériaux de masquage sont bien connus dans le domaine militaire. Ils permettent de protéger un objectif, par exemple un véhicule, en empêchant sa détection par un moyen ennemi.Masking materials are well known in the military field. They make it possible to protect an objective, for example a vehicle, by preventing its detection by an enemy means.

Dispersés à l'aide d'un projectile, ils permettent aussi de réaliser un nuage de masquage dans une zone, permettant ainsi la progression de véhicules ou de fantassins vers ladite zone, à l'abri du nuage.Dispersed using a projectile, they also make it possible to create a masking cloud in an area, thus allowing the progression of vehicles or infantry towards said area, sheltered from the cloud.

Il est ainsi connu de réaliser des masquages vis-à-vis des rayonnements électromagnétiques dans le domaine visible (longueurs d'onde du rayonnement de 380 nanomètres à 780 nanomètres) et dans le domaine infrarouge (longueurs d'onde de 780 nanomètres à 1 millimètre).It is thus known to perform masking vis-à-vis electromagnetic radiation in the visible range (radiation wavelengths from 380 nanometers to 780 nanometers) and in the infrared range (wavelengths from 780 nanometers to 1 millimeter ).

Compte tenu des technologies de détecteurs infrarouge connues, les domaines infrarouge qu'il est plus particulièrement nécessaire de masquer d'un point de vue opérationnel est la bande 8-14 micromètres.Given the known infrared detector technologies, the infrared domains which it is more particularly necessary to mask from an operational point of view is the 8-14 micrometer band.

Pour assurer un masquage infrarouge, il est connu, dans le domaine des munitions de défense rapprochée de véhicules blindés, de disperser une poudre ou des plaquettes métalliques (le plus souvent de laiton ou d'aluminium). À titre d'exemple, le brevet US5531930 décrit une munition dispersant des plaquettes d'aluminium et le brevet US4704966 décrit un matériau de masquage formé de plaquettes de laiton.To ensure infrared masking, it is known, in the field of close defense ammunition for armored vehicles, to disperse a powder or platelets metal (most often brass or aluminum). For example, the patent US5531930 describes ammunition dispersing aluminum platelets and the patent US4704966 describes a masking material formed from brass plates.

Il a également été proposé de disperser d'autres types de matériaux ayant une granulométrie appropriée au masquage des longueurs d'onde du domaine infrarouge (bandes 3-5 micromètres et 8-12 micromètres).It has also been proposed to disperse other types of materials having a particle size suitable for masking the wavelengths of the infrared range (bands 3-5 micrometers and 8-12 micrometers).

Parmi les matériaux connus : la poudre de silice (brevet DE4126016 ), le dioxyde de titane (statutory invention registration USH769), le carbonate de calcium ou de magnésium (brevet FR2396265 ), la poudre de carbone ou les nanotubes de carbone (brevets FR2730742 et FR2421363 ).Among the known materials: silica powder (patent DE4126016 ), titanium dioxide (statutory invention registration USH769), calcium or magnesium carbonate (patent FR2396265 ), carbon powder or carbon nanotubes (patents FR2730742 and FR2421363 ).

Il est enfin connu de disperser de fines gouttelettes formant un brouillard, masquant dans le domaine visible et infrarouge. Pour cela il suffit de disperser un liquide comme le tétrachlorure de titane qui forme un nuage dense au contact de l'humidité de l'air (brevet EP791164 ).Finally, it is known to disperse fine droplets forming a mist, masking in the visible and infrared range. To do this, simply disperse a liquid such as titanium tetrachloride which forms a dense cloud on contact with the humidity of the air (patent EP791164 ).

Les matériaux formant des nuages de gouttelettes, tétrachlorure de titane par exemple, présentent l'inconvénient d'être très corrosifs et de former des nuages tout à la fois corrosifs et toxiques, comprenant généralement de l'acide chlorhydrique. Ils sont le plus souvent écartés au profit de la dispersion de matériaux inertes.The materials forming clouds of droplets, titanium tetrachloride for example, have the disadvantage of being very corrosive and of forming clouds that are both corrosive and toxic, generally comprising hydrochloric acid. They are most often discarded in favor of the dispersion of inert materials.

Les poudres métalliques sont intéressantes mais la masse du bloc de poudre nécessaire pour réaliser un masquage de dimensions relativement importantes (hauteur ou largeur supérieure à 5 mètres) va augmenter fortement le poids de la munition chargée de disperser le matériau, ce qui peut conduire à une déstabilisation du projectile en vol.Metallic powders are interesting but the mass of the block of powder necessary to achieve a masking of relatively large dimensions (height or width greater than 5 meters) will greatly increase the weight of the ammunition responsible for dispersing the material, which can lead to destabilization of the projectile in flight.

Le matériau métallique peut également se compacter au fil du stockage de la munition conduisant à des performances de masquage différentes de celles initialement attendues et peut éventuellement déstabiliser le projectile en vol par un déplacement du centre de gravité.The metallic material can also become compacted during storage of the ammunition, leading to masking performances different from those initially expected and can possibly destabilize the projectile in flight by a displacement of the center of gravity.

Par ailleurs pour que le masquage obtenu puisse avoir une certaine durée, il est nécessaire que les grains du matériau aient une vitesse de descente suffisamment réduite.Furthermore, for the masking obtained to be able to have a certain duration, it is necessary for the grains of the material to have a sufficiently reduced rate of descent.

On adopte ainsi le plus souvent des grains ayant une forme de plaquettes pour que la descente se trouve ralentie. Le brevet US4704966 décrit ainsi un matériau de masquage formé de plaquettes de cuivre ou de laiton.Grains having the shape of pads are thus most often adopted so that the descent is slowed down. The patent US4704966 thus describes a masking material formed of copper or brass plates.

Cependant cuivre ou laiton sont sensibles à la corrosion et ont une densité trop importante pour réaliser des projectiles permettant de réaliser un masquage de taille importante et à distance.However, copper or brass are sensitive to corrosion and have too high a density to produce projectiles allowing large-scale masking to be carried out at a distance.

Il a été proposé par le brevet US5531930 de mettre en œuvre des plaquettes d'aluminium. Cependant ces plaquettes doivent être enrobées pour diminuer les risques d'agglomération dans le corps de munition ce qui complique le procédé de réalisation des munitions. Par ailleurs l'aluminium de faible granulométrie est pyrophorique, c'est-à-dire peut s'enflammer spontanément aux températures ambiantes. Sa mise en œuvre est donc dangereuse et sa dispersion en nuage sur le terrain peut provoquer des incendies.It was proposed by the patent US5531930 to implement aluminum plates. However, these pads must be coated to reduce the risk of agglomeration in the ammunition body, which complicates the process for producing the ammunition. In addition, aluminum of small particle size is pyrophoric, that is to say can ignite spontaneously at ambient temperatures. Its implementation is therefore dangerous and its dispersion in a cloud on the ground can cause fires.

Le but de l'invention est donc de proposer un matériau de masse réduite et ayant une bonne efficacité de masquage vis à vis des rayonnements électromagnétiques dans une gamme de longueurs d'ondes donnée.The object of the invention is therefore to propose a material of reduced mass and having good masking efficiency with respect to electromagnetic radiation in a given range of wavelengths.

L'invention permet ainsi un masquage dans le domaine visible mais aussi avantageusement dans le domaine infrarouge,en particulier dans les gammes 3-5 et 8-14 micromètres.The invention thus allows masking in the visible range but also advantageously in the infrared range, in particular in the 3-5 and 8-14 micrometer ranges.

Le matériau selon l'invention selon la revendication 1 est de mise en œuvre industrielle simple et ne présente aucun risque d'emploi.The material according to the invention according to claim 1 is of simple industrial implementation and does not present any risk of use.

Ce matériau est en particulier compatible avec les réglementations européennes REACH.This material is in particular compatible with European REACH regulations.

L'invention propose également une munition de masquage selon la revendication 6 mettant en œuvre un tel matériau et permettant sa dispersion optimale sur le terrain.The invention also proposes a masking ammunition according to claim 6 implementing such a material and allowing its optimal dispersion on the ground.

Ainsi l'invention a pour objet une munition selon la revendication 6 utilisant de l'oxy-hydroxyde d'aluminium, tel que la boehmite ou la pseudo boehmite, comme matériau de masquage dispersable par une munition pour assurer le masquage d'un objectif vis à vis des rayonnements électromagnétiques dans une gamme de longueurs d'ondes donnée.Thus the subject of the invention is an ammunition according to claim 6 using aluminum oxy-hydroxide, such as boehmite or pseudo-boehmite, as masking material dispersible by ammunition to ensure the masking of a target with respect to electromagnetic radiation in a given range of wavelengths.

Avantageusement l'invention propose une utilisation dans laquelle le masquage est recherché pour des gammes de longueurs d'ondes infrarouges, la granulométrie de l'oxy-hydroxyde d'aluminium étant alors comprise entre 1 et 100 micromètres, avec au moins 90% des grains du matériau qui ont un diamètre moyen compris entre 25 et 45 micromètres. L'invention a également pour objet une munition comprenant un matériau de masquage destiné à être dispersé par une munition pour réaliser un nuage assurant le masquage d'un objectif vis-à-vis des rayonnements électromagnétiques dans une gamme de longueurs d'ondes donnée, matériau caractérisé en ce qu'il comporte au moins un oxy-hydroxyde d'aluminium, tel que la boehmite ou la pseudo boehmite.Advantageously, the invention proposes a use in which masking is sought for ranges of infrared wavelengths, the particle size of the oxy-hydroxide of aluminum then being between 1 and 100 micrometers, with at least 90% of the grains of the material having an average diameter of between 25 and 45 micrometers. The invention also relates to ammunition comprising a masking material intended to be dispersed by ammunition to produce a cloud ensuring the masking of an objective vis-à-vis electromagnetic radiation in a given range of wavelengths, material characterized in that it comprises at least one aluminum oxy-hydroxide, such as boehmite or pseudo-boehmite.

Avantageusement cette munitionest efficace dans une gamme de longueurs d'ondes infrarouges et l'oxy-hydroxyde d'aluminium a une granulométrie comprise entre 1 et 100 micromètres avec au moins 90% des grains du matériau qui ont un diamètre moyen compris entre 25 et 45 micromètres.Advantageously, this ammunition is effective in a range of infrared wavelengths and the aluminum oxy-hydroxide has a particle size between 1 and 100 micrometers with at least 90% of the grains of the material having an average diameter between 25 and 45 micrometers.

Selon une variante de réalisation, l'oxy-hydroxyde d'aluminium pourra être enrobé avec un liant.According to a variant embodiment, the aluminum oxy-hydroxide may be coated with a binder.

Le liant pourra en particulier comprendre de l'alcool polyvinylique (PVA).The binder may in particular comprise polyvinyl alcohol (PVA).

L'invention a enfin pour objet une munition de masquage comprenant une enveloppe renfermant un matériau de masquage et une charge pyrotechnique de dispersion pouvant être actionnée par une fusée, munition caractérisée en ce que le matériau de masquage comporte au moins un oxy-hydroxyde d'aluminium, tel que la boehmite ou la pseudo boehmite.The invention finally relates to a masking ammunition comprising a casing containing a masking material and a pyrotechnic dispersion charge which can be actuated by a rocket, ammunition characterized in that the masking material comprises at least one oxy-hydroxide of aluminum, such as boehmite or pseudo boehmite.

Selon un mode de réalisation, la charge de dispersion est constituée par au moins un matériau explosif disposé dans une canne de dispersion métallique fermée au niveau de son extrémité distante de la fusée, la canne s'étendant axialement dans le matériau de masquage d'une manière coaxiale avec l'axe de la munition.According to one embodiment, the dispersal charge consists of at least one explosive material placed in a metallic dispersion rod closed at its end remote from the fuze, the rod extending axially into the masking material in a manner coaxial with the axis of the munition.

Avantageusement le matériau de masquage pourra comprendre au moins un bloc comprimé directement à l'intérieur de l'enveloppe et autour de la canne de dispersion.Advantageously, the masking material may comprise at least one block compressed directly inside the envelope and around the dispersion rod.

Selon un mode particulier de réalisation le matériau de masquage pourra être comprimé à l'intérieur de l'enveloppe sans mise en œuvre d'un liant.According to a particular embodiment, the masking material can be compressed inside the envelope without using a binder.

L'invention sera mieux comprise à la lecture de la description qui va suivre de modes particuliers de réalisation, description faite en référence aux dessins annexés et dans lesquels :

  • La figure la est une micro photographie d'un premier exemple de grains d'un matériau selon l'invention ;
  • La figure 1b est une micro photographie à plus grande échelle d'un deuxième exemple de grains d'un matériau selon l'invention ;
  • La figure 2 est une vue en coupe longitudinale d'une munition selon un mode de réalisation de l'invention.
The invention will be better understood on reading the following description of particular embodiments, description made with reference to the accompanying drawings and in which:
  • Figure la is a microphotograph of a first example of grains of a material according to the invention;
  • The figure 1b is a microphotograph on a larger scale of a second example of grains of a material according to the invention;
  • The figure 2 is a longitudinal sectional view of an ammunition according to one embodiment of the invention.

La boehmite et la pseudo boehmite sont des oxy-hydroxyde d'aluminium de formule générique AlO(OH). La boehmite est un matériau qui existe naturellement dans le minerai de bauxite. C'est une alumine hydratée ayant une structure cristalline orthorhombique lamellaire.Boehmite and pseudo boehmite are aluminum oxy-hydroxides with the generic formula AlO(OH). Boehmite is a material that occurs naturally in bauxite ore. It is a hydrated alumina having a lamellar orthorhombic crystal structure.

La pseudo boehmite est une désignation courante d'une boehmite finement cristallisée, contenant d'avantage d'eau que la boehmite, et formée de couches cristallines octaédriques séparées par des molécules d'eau. La publication « Crystal chemistry of Boehmite de Rodney Tettenhorst et Douglas A Hofman (Clays and clay minerais vol 28, n°5, 373-380, 1980 ) » décrit des synthèses comparatives de boehmite et pseudo boehmite et leurs comparaisons cristallographiques.Pseudo boehmite is a common designation for a finely crystallized boehmite, containing more water than boehmite, and formed of octahedral crystalline layers separated by water molecules. The publication “Crystal chemistry of Boehmite by Rodney Tettenhorst and Douglas A Hofman (Clays and clay minerals vol 28, n°5, 373-380, 1980 )” describes comparative syntheses of boehmite and pseudo-boehmite and their crystallographic comparisons.

Ces matériaux sont faciles à approvisionner et sont couramment utilisés dans l'industrie pour la préparation d'abrasifs, de revêtements céramiques, d'encres, de papier, de catalyseurs...These materials are easy to source and are commonly used in industry for the preparation of abrasives, ceramic coatings, inks, paper, catalysts...

Ils sont aussi utilisés comme produits intermédiaires dans la métallurgie de l'aluminium.They are also used as intermediate products in aluminum metallurgy.

Ces matériaux n'ont à ce jour jamais été mis en œuvre dans le domaine de l'armement et en particulier n'a jamais été incorporé comme chargement d'une munition fumigène.These materials have to date never been implemented in the field of armaments and in particular have never been incorporated as a load of a smoke-producing ammunition.

Les essais conduits par la déposante ont permis de constater que la boehmite, et plus particulièrement la boehmite finement cristallisée ou pseudo boehmite, pouvait être dispersée dans l'air sous forme de nuage et que les nuages ainsi réalisés avaient une certaine durabilité favorisant un masquage d'une cible, par exemple dans le domaine visible.The tests conducted by the applicant have shown that boehmite, and more particularly finely crystallized boehmite or pseudo boehmite, can be dispersed in the air in the form of a cloud and that the clouds thus produced have a certain durability favoring a masking of a target, for example in the visible domain.

Il a en particulier été constaté que la vitesse de chute des particules du nuage était relativement lente avec des vitesses de chute inférieure à 1 m/s.In particular, it was found that the falling velocity of the cloud particles was relatively slow with falling velocities of less than 1 m/s.

Un tel comportement est dû d'une part à la masse réduite du matériau dont la densité moyenne du matériau lui-même est de l'ordre de 3 à 3,07 et dont la densité apparente de la poudre en vrac non compactée est inférieure à 1,5, et est dû d'autre part à la finesse des cristaux de boehmite qui sont morphologiquement en forme de plaques ou de feuillets comme illustré dans la photo microscopique de la figure la, ou encore en forme de sphères portant un creux médian comme représenté dans la figure 1b).Such behavior is due, on the one hand, to the reduced mass of the material, the average density of the material itself of which is of the order of 3 to 3.07, and the bulk density of the uncompacted bulk powder of which is less than 1.5, and is due on the other hand to the fineness of the boehmite crystals which are morphologically in the form of plates or sheets as illustrated in the microscopic photo of figure la, or even in the form of spheres carrying a median hollow as represented in the figure 1b ).

Ces formes favorisent une chute lente des grains et la durabilité du nuage qui est par ailleurs peu sensible au vent.These shapes favor a slow fall of the grains and the durability of the cloud which is moreover not very sensitive to the wind.

La poudre du matériau possède beaucoup d'avantages.The powder of the material has many advantages.

D'un point de vue procédé de chargement des corps de munition, cette poudre n'est pas un matériau répertorié dans une classe de risque pyrotechnique.From an ammunition body loading process point of view, this powder is not a material listed in a pyrotechnic risk class.

Le remplissage d'un corps de munition est aisé. Il ne nécessite pas d'équipements de protection individuels particuliers, hormis un masque à poussières et des lunettes de sécurité.Filling an ammunition body is easy. It does not require any particular personal protective equipment, apart from a dust mask and safety goggles.

Le chargement des munitions pourra être effectué en vrac ou par compression, cependant les performances de masquage d'un chargement comprimé seront meilleures.The loading of the ammunition can be carried out in bulk or by compression, however the masking performance of a compressed load will be better.

Le chargement par compression sera effectué en mettant en œuvre des installations classiques et peu coûteuse, telle qu'une presse hydraulique.The loading by compression will be carried out by implementing conventional and inexpensive installations, such as a hydraulic press.

Du point de vue des propriétés intrinsèques de la poudre, cette dernière est inerte, contrairement à l'aluminium pulvérulent.From the point of view of the intrinsic properties of the powder, the latter is inert, unlike powdered aluminium.

La densité apparente de la poudre en vrac est inférieure à 1,5, le matériau est donc particulièrement léger.The bulk density of the bulk powder is less than 1.5, so the material is particularly light.

Le nuage généré par la suspension de cette poudre n'est pas corrosif et il est très faiblement toxique pour l'homme et l'environnement.The cloud generated by the suspension of this powder is not corrosive and it is very slightly toxic for humans and the environment.

Par un choix judicieux de la granulométrie, le nuage généré permet d'assurer un masquage dans les gammes infrarouges de 3 à 5 et 8 à 14 micromètreset dans le spectre du visible. Le masquage est principalement assuré par absorption du rayonnement.By a judicious choice of particle size, the generated cloud ensures masking in the infrared ranges of 3 to 5 and 8 to 14 micrometers and in the visible spectrum. The masking is mainly ensured by absorption of the radiation.

L'humidité de l'air ou le taux d'oxygène n'ont que peu d'influence sur l'efficacité de l'aérosol. La poudre ne réagit pas, ni avec l'air, ni avec l'eau de l'atmosphère.Air humidity or oxygen levels have little influence on the effectiveness of the aerosol. The powder does not react, neither with the air nor with the water in the atmosphere.

La poudre de boehmite ou pseudo boehmite est disponible dans le commerce pour différents types de granulométries.Boehmite powder or pseudo boehmite is commercially available for different types of grain sizes.

Cette poudre est généralement réalisée par un procédé classique de type sol-gel comprenant une étape d'hydrolyse et condensation d'un alkoxyde d'aluminium avec un excès d'eau pour former un hydroxyde d'aluminium, une étape de redissolution du précipité obtenu pour former le Sol puis formation du Gel par séchage du Sol.This powder is generally produced by a conventional method of the sol-gel type comprising a step of hydrolysis and condensation of an aluminum alkoxide with an excess of water to form an aluminum hydroxide, a step of redissolution of the precipitate obtained to form the Sol then formation of the Gel by drying of the Sol.

Ce procédé Sol-Gel a été mis au point par B.E Yoldas. Pour plus de détails sur les procédés Sol-Gel il est possible de consulter l'ouvrage « Handbook of Sol-Gel science and technology » de Sumio Sakka (ISBN : 1-4020-7968-0 ).This Sol-Gel process was developed by BE Yoldas. For more details on the Sol-Gel processes it is possible to consult the book “Handbook of Sol-Gel science and technology” by Sumio Sakka (ISBN: 1-4020-7968-0 ).

La finesses et la morphologie des grains de boehmite ou pseudo boehmite est modifiable en mettant en œuvre une tour de séchage par atomisation. Une telle tour permet d'assurer un séchage des solutions Gel de boehmite ou de pseudo boehmite industrielles tout en permettant de calibrer la granulométrie souhaitée.The fineness and morphology of boehmite or pseudo boehmite grains can be modified by implementing a spray drying tower. Such a tower makes it possible to ensure drying of the industrial boehmite or pseudo-boehmite gel solutions while making it possible to calibrate the desired particle size.

Les tours d'atomisation sont bien connues dans le domaine des procédés industriels de production de matériaux pulvérulents et il n'est donc pas nécessaire de les décrire plus en détails.Atomization towers are well known in the field of industrial processes for the production of powdery materials and it is therefore not necessary to describe them in more detail.

On paramètrera cette tour d'atomisation de façon à obtenir une poudre dont la granulométrie à d(0,9) est comprise entre 25 et 35 micromètres, c'est-à-dire que 90% des grains du matériau ont un diamètre moyen compris entre 25 et 35 micromètres, la granulométrie globale des grains se répartissant par ailleurs entre 1 micromètre et 100 micromètres. D'une façon classique l'augmentation de la pression d'atomisation permet de diminuer la taille des grains de la poudre.This atomization tower will be parameterized so as to obtain a powder whose particle size at d(0.9) is between 25 and 35 micrometers, that is to say that 90% of the grains of the material have an average diameter of between 25 and 35 micrometers, the overall particle size of the grains being further distributed between 1 micrometer and 100 micrometers. Conventionally, increasing the atomization pressure makes it possible to reduce the size of the grains of the powder.

Un tel choix de granulométrie conduit à des grains G1,G2 en forme de sphères portant un creux médian G3 comme représenté dans la figure 1b). Cette granulométrie assure par ailleurs un masquage dans les gammes de longueurs d'ondes infrarouges dans les bandes de 3 à 5 et 8 à 14 micromètres.Such a choice of particle size leads to grains G1, G2 in the shape of spheres carrying a median hollow G3 as represented in the figure 1b ). This particle size also provides masking in the infrared wavelength ranges in the bands of 3 to 5 and 8 to 14 micrometers.

À titre de variante les grains d'oxy-hydroxyde d'aluminium pourront être enrobés avec un liant.As a variant, the aluminum oxy-hydroxide grains could be coated with a binder.

Une telle variante permettra d'augmenter la taille des granules formés et facilitera leur compaction ultérieure dans une munition. Elle permet aussi de limiter la dispersion des grains du matériau lors des étapes de fabrication, notamment par limitation du taux de poussière.Such a variant will make it possible to increase the size of the granules formed and will facilitate their subsequent compaction in ammunition. It also makes it possible to limit the dispersion of the grains of the material during the manufacturing stages, in particular by limiting the level of dust.

Le liant pourra par exemple comprendre de l'alcool polyvinylique (PVA) dans une proportion de 1% à 4% en masse.The binder may for example comprise polyvinyl alcohol (PVA) in a proportion of 1% to 4% by mass.

Le liant est incorporé à la solution des grains d'oxy-hydroxyde d'aluminium dans l'eau et avant l'atomisation.The binder is incorporated into the solution of the aluminum oxy-hydroxide grains in water and before atomization.

La figure 2 montre en coupe longitudinale un exemple d'un mode de réalisation d'une munition 1 de masquage selon l'invention, la munition auyant une forme classique d'un projectile avec un axe de symétrie rotationel X-X'.The figure 2 shows in longitudinal section an example of an embodiment of a masking ammunition 1 according to the invention, the ammunition having a conventional shape of a projectile with an axis of rotational symmetry X-X'.

Cette munition est destinée à être tirée par un système d'arme non représenté en direction d'une zone de terrain. Elle a pour fonction de générer au niveau de ladite zone un nuage de masquage infrarouge ou visible.This ammunition is intended to be fired by a weapon system not shown in the direction of an area of land. Its function is to generate an infrared or visible masking cloud at said zone.

La munition 1 comprend une enveloppe 2 renfermant un matériau de masquage 3 et une charge pyrotechnique de dispersion 4 pouvant être actionnée par une fusée 5, par exemple de type chronométrique pouvant dissiper une flamme dans la direction axiale X-X'.The ammunition 1 comprises an envelope 2 containing a masking material 3 and a pyrotechnic dispersion charge 4 which can be actuated by a rocket 5, for example of the type chronometer capable of dissipating a flame in the axial direction X-X'.

L'enveloppe porte à sa partie arrière une ceinture 12 permettant de façon classique d'assurer l'étanchéité aux gaz lors du tir dans le tube d'une arme.The casing carries at its rear part a belt 12 allowing in a conventional way to ensure gas tightness during firing in the barrel of a weapon.

La charge de dispersion 4 est constituée par au moins un matériau explosif, par exemple des comprimés d'un explosif associant hexogène et cire ou d'un explosif composite, qui est disposé dans une canne de dispersion métallique 6 fermée au niveau de son extrémité 6a distante de la fusée.The dispersion charge 4 consists of at least one explosive material, for example tablets of an explosive combining hexogen and wax or of a composite explosive, which is placed in a metal dispersion rod 6 closed at its end 6a away from the rocket.

La canne 6 est solidaire d'une bague de liaison 7 qui est fixée à l'enveloppe 2, par exemple par un filetage 8. La canne 6 s'étend axialement dans le matériau de masquage 3 dans la dierction de l'axe X-X' de la munition 1.The rod 6 is integral with a connecting ring 7 which is fixed to the casing 2, for example by a thread 8. The rod 6 extends axially in the masking material 3 in the direction of the axis X-X' of ammunition 1.

La bague de liaison 7 est réalisée de préférence de façon monobloc avec la canne 6. Cet ensemble sera par exemple réalisé en aluminium pour réduire la masse de la munition.The connecting ring 7 is preferably made in one piece with the rod 6. This assembly will for example be made of aluminum to reduce the mass of the ammunition.

La bague de liaison 7 renferme un logement interne 9 qui reçoit un relais de détonation 10 et qui est en communication avec la cavité de la canne 4. Elle comporte aussi un taraudage 11 permettant de fixer la fusée 5.The connecting ring 7 contains an internal housing 9 which receives a detonation relay 10 and which is in communication with the cavity of the rod 4. It also comprises a thread 11 allowing the fuse 5 to be fixed.

La quantité d'explosif de la charge de dispersion 4 est définie suffisante pour assurer la rupture, tant de la canne 6 que de l'enveloppe 2 de la munition.The quantity of explosive in the dispersal charge 4 is defined as sufficient to ensure the rupture, both of the rod 6 and of the casing 2 of the ammunition.

Lorsque la munition est lancée par un canon par exemple pour masquer un objectif, à un instant donné sur le trajectoire de la munition ou par l'impact de la munition, la fusée 5 provoque l'initiation du relais de détonation 10 qui lui-même initie la charge de dispersion 4.When the ammunition is launched by a cannon, for example to mask a target, at a given instant on the trajectory of the ammunition or by the impact of the ammunition, the fuse 5 causes the initiation of the detonation relay 10 which itself initiates the dispersal charge 4.

L'éclatement de la charge de dispersion 4 met en contrainte le matériau de masquage 3 qui provoque l'éclatement de l'enveloppe 2 de la munition et la dispersion du matériau de masquage 3.The bursting of the dispersion charge 4 stresses the masking material 3 which causes the bursting of the casing 2 of the ammunition and the dispersion of the masking material 3.

Afin d'améliorer la répartition du nuage de masquage on donnera à la canne 6 une longueur telle qu'il subsiste en arrière de la canne 6 une distance D, au moins égale à la moitié du diamètre interne d de l'enveloppe 2. Une telle disposition permet d'éviter de réduire la densité du nuage de masquage en son centre. Une canne 6 trop longue risque en effet de créer un nuage annulaire.In order to improve the distribution of the masking cloud, the rod 6 will be given a length such that there remains behind the rod 6 a distance D, at least equal to half the internal diameter d of the envelope 2. such an arrangement makes it possible to avoid reducing the density of the masking cloud at its center. A rod 6 that is too long runs the risk of creating an annular cloud.

Le matériau de masquage 3 est un matériau comprenant essentiellement de l'oxy-hydroxyde d'aluminium, tel que la boehmite ou la pseudo boehmite, dont les grains sont éventuellement enrobés par un liant tel que l'alcool polyvinylique (PVA).The masking material 3 is a material essentially comprising aluminum oxy-hydroxide, such as boehmite or pseudo-boehmite, the grains of which are optionally coated with a binder such as polyvinyl alcohol (PVA).

De préférence le matériau 3 est mis en place dans l'enveloppe 2 par compression directement dans l'enveloppe. On réalise ainsi au moins un bloc comprimé directement à l'intérieur de l'enveloppe 2 et autour de la canne de dispersion 6.Preferably the material 3 is placed in the envelope 2 by compression directly in the envelope. At least one compressed block is thus produced directly inside the casing 2 and around the dispersion rod 6.

Conformément à ce mode de réalisation de l'invention, l'enveloppe 2 porte la bague de liaison 7 prolongée par la canne 6. Il est aisé à l'aide d'un piston percé au diamètre de la canne 6 de réaliser une compression in situ du matériau de masquage 3, sans qu'il soit nécessaire de réaliser un usinage ultérieur du bloc comprimé pour permettre le passage de la canne 6. Il en résulte une grande facilité de fabrication de la munition 1.In accordance with this embodiment of the invention, the casing 2 carries the connecting ring 7 extended by the cane 6. It is easy with the aid of a piston pierced to the diameter of the cane 6 to carry out an in situ compression of the masking material 3, without it being necessary to carry out subsequent machining of the compressed block to allow the passage of the rod 6. This results in a great ease of manufacture of the ammunition 1.

La compression pourra être réalisée en une ou plusieurs passes en fonction de la longueur de la munition 1.The compression may be carried out in one or more passes depending on the length of the ammunition 1.

Des rondelles de calage 13 seront positionnées entre l'arrière du bloc de matériau de masquage 3 et un culot 14 assurant la fermeture de l'enveloppe 2 à sa partie arrière. Les rondelles servent à compenser les tolérances de fabrication sur la longueur du bloc comprimé du matériau de masquage 3 de façon à ce que bloc soit bien immobilisé axialement dans la munition 1.Wedging washers 13 will be positioned between the rear of the block of masking material 3 and a cap 14 ensuring the closure of the envelope 2 at its rear part. The washers are used to compensate for manufacturing tolerances on the length of the compressed block of masking material 3 so that the block is well immobilized axially in the ammunition 1.

On notera que la charge de dispersion 4 peut n'être mise en place qu'après chargement du matériau de masquage 3.Les opérations de compression du matériau de masquage 3 sont donc effectuées sur une munition 1 complètement inerte.It will be noted that the dispersion charge 4 can only be put in place after the masking material 3 has been loaded. The masking material 3 compression operations are therefore carried out on a completely inert ammunition 1.

Selon un mode de réalisation particulièrement avantageux, on pourra comprimer le matériau de masquage 3 à l'intérieur de l'enveloppe 2 sans mise en œuvre d'un liant. Dans ce cas on ajoutera cependant au matériau de masquage un solvant, par exemple le méthyléthylcétone en proportion réduite (5% à 20% en masse, pour limiter les poussières. Le solvant pourra ou non être évacué par séchage avec aspiration avant mise en place du culot 14.According to a particularly advantageous embodiment, the masking material 3 can be compressed inside the casing 2 without using a binder. In this case, however, a solvent will be added to the masking material, for example methyl ethyl ketone in a reduced proportion (5% to 20% by mass, to limit dust. The solvent may or may not be evacuated by drying with suction before setting up the base 14.

Les essais réalisés ont permis de vérifier que le matériau de masquage 3 selon l'invention se comprimait aisément, même sans liant. Le bloc obtenu est particulièrement compact et solide. Aucun risque de dislocation lors du tir n'est à craindre. Aucune décantation du matériau de masquage lors des phases de stockage n'est à craindre non plus.The tests carried out made it possible to verify that the masking material 3 according to the invention compressed easily, even without a binder. The block obtained is particularly compact and solid. No risk of dislocation during firing is to be feared. No settling of the masking material during the storage phases is to be feared either.

Il est évident que la poudre du matériau de masquage peut être comprimé dans un moule séparé pour former un bloc comprimé que l'on peut manipuler pour l'introduire dans l'enveloppe 2.It is obvious that the powder of the masking material can be compressed in a separate mold to form a compressed block which can be manipulated to introduce it into the envelope 2.

De manière alternative il n'est pas exclu de remplir l'enveloppe 2 en versant la poudre non-comprimé dans l'enveloppe 2 et de mettre en place le culot 14 sans avoir comprimé la poudre préalablement.Alternatively, it is not excluded to fill the envelope 2 by pouring the uncompressed powder into the envelope 2 and to set up the base 14 without having compressed the powder beforehand.

De façon surprenante, l'énergie communiquée par la charge de dispersion 4 lors de son initiation suffit à fragmenter le bloc du matériau de masquage qui redevient hors de l'enveloppe 2 un matériau pulvérulent formant le nuage de masquage souhaité et avec les performances attendues, en particulier dans le domaine infrarouge.Surprisingly, the energy communicated by the dispersion charge 4 during its initiation is sufficient to fragment the block of masking material which, outside the envelope 2, becomes a powdery material forming the desired masking cloud and with the expected performance, especially in the infrared range.

Il est bien entendu possible de réaliser des munitions 1 selon l'invention qui ne sont pas tirées par un canon ou un tube de mortier mais qui équipent les tubes lanceur des munitions de défense rapprochée des véhicules blindés. Dans ce cas, le nuage de masquage aura pour effet de dissimuler le véhicule qui tire la munition selon l'invention.It is of course possible to produce ammunition 1 according to the invention which is not fired by a cannon or a mortar tube but which equips the launcher tubes of the close defense ammunition of armored vehicles. In this case, the masking cloud will have the effect of concealing the vehicle which fires the ammunition according to the invention.

Il est clair que l'oxy-hydroxyde d'aluminium comme matériau de masquage 3 ne doit pas nécessairement se présenter sous la forme de boehmite ou de la pseudo boehmite.It is clear that the aluminum oxy-hydroxide as masking material 3 does not necessarily have to be in the form of boehmite or pseudo-boehmite.

Claims (21)

  1. - Use of aluminum oxyhydroxide, such as boehmite or pseudoboehmite, as a masking material (3) which is dispersible by an ammunition (1) or a launcher to mask a target with respect to electromagnetic radiation in a given wavelength range.
  2. - Use according to claim 1 for masking a target for a range of infrared wavelengths, characterized in that the aluminum oxyhydroxide is used in an optionally compressed powder form of which the particle size is between 1 and 100 micrometers, with at least 90% of the grains (G1, G2) of the masking material (3) having an average diameter of between 25 and 35 micrometers.
  3. - Use according to either claim 1 or claim 2 for masking a target for electromagnetic radiation in the band of infrared wavelengths from 8 to 14 micrometers, in the band of infrared wavelengths from 3 to 5 micrometers, and in the visible band.
  4. - Use according to any of the preceding claims, characterized in that the aluminum oxyhydroxide is dispersed in the form of a cloud.
  5. - Use according to either claim 2 or claim 3, characterized in that the aluminum oxyhydroxide is dispersed by means of an explosive ammunition comprising an optionally compressed aluminum oxyhydroxide powder.
  6. - Masking ammunition comprising a casing which contains a masking material (3) and a pyrotechnic dispersion charge (4) which can be actuated by a fuze (5), characterized in that the masking material (3) comprises at least an aluminum oxyhydroxide such as boehmite or pseudoboehmite.
  7. - Masking ammunition according to claim 6, characterized in that the masking material (3) consists substantially of aluminum oxyhydroxide.
  8. - Masking ammunition according to either claim 6 or claim 7 which is effective in a range of infrared wavelengths and in the visible range, characterized in that the aluminum oxyhydroxide is a powder of which the particle size is between 1 and 100 micrometers with at least 90% of the grains (G1, G2) of the masking material (3) having an average diameter of between 25 and 35 micrometers.
  9. - Masking ammunition according to any of claims 6 to 8 which is effective in a range of infrared wavelengths, characterized in that the aluminum oxyhydroxide has a particle size of the grains (G1, G2) in the form of platelets or flakes or in the form of spheres having a central recess (G3).
  10. - Masking ammunition according to either claim 8 or claim 9, characterized in that the grains (G1, G2) of aluminum oxyhydroxide are coated with a binder.
  11. - Masking ammunition according to claim 10, characterized in that the binder comprises polyvinyl alcohol (PVA).
  12. - Masking ammunition according to claim 11, characterized in that the binder comprises polyvinyl alcohol (PVA) in a proportion of 1 % to 4% by mass.
  13. - Masking ammunition according to any of claims 8 to 12, characterized in that it is in the form of a compressed powder block.
  14. - Masking ammunition according to any of claims 6 to 13, characterized in that the pyrotechnic dispersion charge (4) consists of at least an explosive material arranged in a dispersion rod (6) which is closed at the end (6a) thereof that is remote from the fuze (5), the dispersion rod (6) extending axially in the masking material (3) and in the axis of the ammunition.
  15. - Masking ammunition according to claim 14, characterized in that the dispersion rod (6) is a metal rod.
  16. - Masking ammunition according to either claim 14 or claim 15, characterized in that the masking material (3) is enclosed in the casing (2) by a base (14) that closes the casing (2) at its rear portion and in that the length of the dispersion rod (6) is such that there remains an axial distance (D) between the rod (6) and the base (14).
  17. - Masking ammunition according to claim 16, characterized in that the distance (D) between the rod (6) and the base (14) is at least equal to half the internal diameter (d) of the casing 2.
  18. - Masking ammunition according to any of claims 14 to 17, characterized in that the explosive material of the pyrotechnic dispersion charge (4) comprises tablets of an explosive which combines hexogen and wax or of a composite explosive.
  19. - Masking ammunition according to claim 18, characterized in that the quantity of explosive of the dispersion charge (4) is sufficient to rupture both the rod (6) and the casing (2).
  20. - Masking ammunition according to any of claims 13 to 19, characterized in that the masking material (3) comprises at least one compressed block directly inside the casing (2) and around the dispersion rod (6).
  21. - Masking ammunition according to claim 20, characterized in that the masking material (3) is compressed inside the casing (2) without the use of a binder.
EP18779054.8A 2017-10-23 2018-09-14 Use of material for masking a target and ammunition for dispersing such a masking material Active EP3701214B1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
SI201830690T SI3701214T1 (en) 2017-10-23 2018-09-14 Use of material for masking a target and ammunition for dispersing such a masking material
RS20220745A RS63479B1 (en) 2017-10-23 2018-09-14 Use of material for masking a target and ammunition for dispersing such a masking material
HRP20221002TT HRP20221002T1 (en) 2017-10-23 2018-09-14 Use of material for masking a target and ammunition for dispersing such a masking material [

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
BE2017/5755A BE1025655B1 (en) 2017-10-23 2017-10-23 Masking material and use of lens masking material and ammunition for dispersing such masking material
PCT/IB2018/057034 WO2019081993A1 (en) 2017-10-23 2018-09-14 Masking material and use of the material for masking a target and ammunition for dispersing such a masking material

Publications (2)

Publication Number Publication Date
EP3701214A1 EP3701214A1 (en) 2020-09-02
EP3701214B1 true EP3701214B1 (en) 2022-05-18

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EP18779054.8A Active EP3701214B1 (en) 2017-10-23 2018-09-14 Use of material for masking a target and ammunition for dispersing such a masking material

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US (1) US11079208B2 (en)
EP (1) EP3701214B1 (en)
BE (1) BE1025655B1 (en)
CA (1) CA3079576A1 (en)
DK (1) DK3701214T3 (en)
ES (1) ES2923681T3 (en)
HR (1) HRP20221002T1 (en)
HU (1) HUE059236T2 (en)
LT (1) LT3701214T (en)
PL (1) PL3701214T3 (en)
PT (1) PT3701214T (en)
RS (1) RS63479B1 (en)
SI (1) SI3701214T1 (en)
WO (1) WO2019081993A1 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102018129786B4 (en) * 2018-11-26 2022-03-03 Rheinmetall Waffe Munition Gmbh Test and/or practice ammunition
DE102020002776A1 (en) 2020-05-09 2021-11-11 Diehl Defence Gmbh & Co. Kg Device arrangement, projectile and method

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DE2729055B2 (en) * 1977-06-28 1979-07-12 Nico-Pyrotechnik Hanns-Juergen Diederichs Kg, 2077 Trittau Method of creating dense clouds for military purposes
SE418495B (en) 1978-03-31 1981-06-09 Lennart Holm APPLICATION OF PARTICLES OF ACTIVE CARBON IN AEROSOLS INTENDED FOR RADIATION ABSORPTION SPECIFICALLY IN IR
FR2730742A1 (en) 1983-02-08 1996-08-23 Armement Et D Etudes Sae Alset Aerosol powder for screening against sighting by infra red
US4704966A (en) 1986-05-16 1987-11-10 Aai Corporation Method of forming IR smoke screen
DE4126016C1 (en) 1991-08-06 1992-11-12 Dynamit Nobel Ag, 5210 Troisdorf, De Non-moisture sensitive, artificial camouflaging mixt. - comprises metal dust solid particles e.g. of iron@ surrounded by hydrophobic silica gel
ATE129650T1 (en) * 1992-03-13 1995-11-15 Solvay Umweltchemie Gmbh ABRASION-RESISTANT SUPPORTED CATALYST.
DE4212633A1 (en) * 1992-04-15 1993-10-21 Inst Neue Mat Gemein Gmbh Process for the production of surface-modified nanoscale ceramic powders
US5531930A (en) 1994-04-12 1996-07-02 Israel Institute For Biological Research Aluminum metal composition flake having reduced coating
NO180216B1 (en) 1994-11-11 1997-03-24 Forsvarets Forsknings Device by smoke grenade
DE10325436A1 (en) * 2003-06-05 2004-12-23 Bayer Materialscience Ag Process for the production of anti-fog scratch-resistant coating systems
US7166271B2 (en) * 2003-10-28 2007-01-23 J.M. Huber Corporation Silica-coated boehmite composites suitable for dentifrices
FR2879439B1 (en) * 2004-12-17 2007-02-09 Oreal COSMETIC EMULSION COMPRISING SOLID PARTICLES.
EP1880041A4 (en) * 2005-04-26 2010-06-09 Tda Research Inc Releasable corrosion inhibitor compositions
KR20100138880A (en) * 2008-02-19 2010-12-31 알베마를 유럽 에스피알엘 A process for the production of nanodispersible boehmite and the use thereof in flame retardant synthetic resins
US9828304B1 (en) * 2015-04-21 2017-11-28 The United States Of America As Represented By The Secretary Of The Army Composites of porous pyrophoric iron and ceramic and methods for preparation thereof

Also Published As

Publication number Publication date
PL3701214T3 (en) 2022-09-19
US11079208B2 (en) 2021-08-03
RS63479B1 (en) 2022-08-31
PT3701214T (en) 2022-07-13
DK3701214T3 (en) 2022-07-25
SI3701214T1 (en) 2022-07-29
ES2923681T3 (en) 2022-09-29
EP3701214A1 (en) 2020-09-02
US20200309494A1 (en) 2020-10-01
HRP20221002T1 (en) 2022-11-11
CA3079576A1 (en) 2019-05-02
LT3701214T (en) 2022-06-27
BE1025655B1 (en) 2019-05-21
BE1025655A1 (en) 2019-05-16
HUE059236T2 (en) 2022-10-28
WO2019081993A1 (en) 2019-05-02

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