Classifications

• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06D—MEANS FOR GENERATING SMOKE OR MIST; GAS-ATTACK COMPOSITIONS; GENERATION OF GAS FOR BLASTING OR PROPULSION (CHEMICAL PART)
  • C06D3/00—Generation of smoke or mist (chemical part)
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B27/00—Compositions containing a metal, boron, silicon, selenium or tellurium or mixtures, intercompounds or hydrides thereof, and hydrocarbons or halogenated hydrocarbons
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S149/00—Explosive and thermic compositions or charges
  • Y10S149/11—Particle size of a component
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S149/00—Explosive and thermic compositions or charges
  • Y10S149/11—Particle size of a component
  • Y10S149/114—Inorganic fuel

Definitions

• the technical sector of the present invention is that of fusible smoke pyrotechnic compositions making it possible to camouflage any target by preventing the transmission of the infrared radiation emitted by it.
• the fuming pyrotechnic compositions based on hexachloroethane (oxidizing agent) and zinc oxide (reducing agent) are well known to those skilled in the art and it will be possible, by way of illustration, to refer to patent US Pat. 779. This kind of composition produces a white screen which is ineffective with respect to infrared sensors working in the windows of transparency of the atmosphere which are 3-5 ⁇ m and 7-14 ⁇ m.
• Patent FR-A-2 560 186 is also known which proposes a pyrotechnic composition intended for the production of opaque smoke with infrared radiation from a target to a thermal sensor, characterized in that it comprises a generating compound, by thermal decomposition of carbon particles whose size is between 1 and 14 ⁇ m, an oxidation-reduction system reacting at a temperature above 1000 ° C and a binder.
• composition can include the following ternary system: - 15 to 25 parts by weight of metal powder, for example magnesium, - 50 to 85 parts by weight of hexachlorobenzene or hexachlorethane (oxidant), - 0 to 30 parts of naphthalene (carbon generator).
• the smoke-producing compositions are most of the time powdery mixtures used by compression. These materials do not always have optimal mechanical properties, are difficult to machine for low compression ratios and are produced individually. Manufacturing requires heavy means such as mixers, mixers, dryers, presses which prohibit the manufacture of large products.
• the manufacturing diagram is complex and the unit price high.
• smoke-producing pyrotechnic compositions intended for the production of a smoke screen preventing the transmission of infrared radiation comprise the following components: - a reducing agent (most commonly magnesium powder) - an oxidant (hexachloroethane or hexachlorobenzene) - a carbon generating binder (naphthalene, anthracene) - a fluorinated binder (Polyvinylidene fluoride).
• a reducing agent most commonly magnesium powder
• an oxidant hexachloroethane or hexachlorobenzene
• carbon generating binder naphthalene, anthracene
• fluorinated binder Polyvinylidene fluoride
• compositions have two drawbacks: - for reasons of toxicity, hexachlorobenzene is no longer commercially available on European markets, - In addition to the problems of industrial implementation mentioned above, they require the mixture of at least four components.
• the object of the present invention is to provide a pyrotechnic composition producing a screen made up of carbon particles to make a target undetectable by a receiver or a missile sensor, but which can be produced by simple casting.
• the subject of the invention is therefore a flowable pyrotechnic composition intended for the production of opaque smoke to prevent the transmission of infrared radiation from a target to a sensor, of the type comprising a general compound.
• carbon particle generator whose dimensions are between 1 and 14 ⁇ m, characterized in that it comprises a halogenated condensed carbon compound fusible between 75 and 120 ° C whose halogenation rate is greater than 3, a chlorinated carbon compound and a metallic powder, reacting together at a temperature of the order of 1500 ° C.
• the carbon compound can be represented by chlorinated naphthalene, the fluorinated compound by polyvinylidene fluoride and the metal powder by magnesium.
• the composition may contain 50 to 90 parts by weight of carbonaceous compound, 8 to 10 parts by weight of polyvinylidene fluoride and 15 to 25 parts by weight of metal powder.
• the pyrotechnic composition according to the invention meets the following three criteria: - a high combustion regime, - an oxygenated combustion medium, - the presence in the composition of a compound with condensed nuclei.
• the condensed nuclei can advantageously carry halogen atoms (fluorine, chlorine) and / or have the greatest possible number of carbon atoms / number of hydrogen atoms. We then take advantage of the presence of these condensed nuclei, associated with the first two criteria, to generate carbon forming a screen of particles with a broad spectrum. Indeed, the presence of oxygen as well as an unfavorable C / H ratio would cause the formation of gaseous molecules (CO2 and H2O) transparent in the visible and the infrared.
• halogen atoms fluorine, chlorine
• the oxidant is then chlorine or fluorine, carried by another molecule, acid generator which, by condensing on atmospheric water vapor, forms an aerosol of solid particles, effective in the spectrum visible against the sensors.
• the oxidizing compound generating carbon particles can be an industrial chlorinated naphthalene called clonacire whose chlorine substitution rate varies between 3.4, and 3.6.
• clonacire 90 and clonacire 115 Two clonacires are marketed: clonacire 90 and clonacire 115, the melting points of which are 90 and 115 ° C respectively.
• the size of the carbon particles is between 1 and 14 ⁇ m.
• An advantage of the pyrotechnic composition and of the smoke ammunition according to the invention lies in the fact that the cloud of opaque infrared smoke consists of fine carbon particles chemically generated homogeneously with a sufficient flow rate.
• Another advantage lies in the fact that it is possible to master the essential factors: the combustion speed of the composition, which makes it possible to obtain a sufficient mass flow rate, - the combustion temperature which must be high and which conditions the good particle size distribution of the carbon particles;
• compositions are pourable or extrudable.
• a family of fusible compositions between 75 and 120 ° C.
• a double objective is achieved: economic by improving production costs, and technological by filling in complicated geometric shapes.
• These compositions lend themselves better to modern industrialization and their interests are obvious: - suppression of compression as a means of implementation (these compositions can however be implemented by compression), - the possibility of pouring large-diameter breads to supply generators intended for area defense, which is impossible with compressed compositions, - optimal density, - good machinability, - good impact resistance.
• Another advantage is that it is possible to incorporate fibers of chemical origin with a carbon skeleton, the pyrolysis of which at high temperature will generate opacifying carbon particles.
• the overall composition can be obtained by mixing only 3 components: reducing agent - chlorinated naphthalene - polyvinylidene fluoride.
• the metal powder is first subjected to a steaming at approximately 50 ° C for 24 hours.
• the fusible carbon compound is then introduced into the reactor and the mixture is heated with stirring to a temperature 15 ° C higher than the melting level.
• the polyvinylidene fluoride and the reducing agent are then successively added and the melting temperature is maintained for ten minutes with stirring to homogenize the mixture well.
• the casting can then take place.
• the breads obtained are then taken up by machining in order to eliminate shrinkage.
• the combustion speed is measured on a cylindrical test tube 3cm long and 3cm in diameter produced by compression of 6.107 Pa.
• the occulting power is measured using two thermal cameras working in the bands 3-5 and 8-12 um arranged 4.5 m from an emitter constituted by an extended source of 20 cm of coast increased to 200 ° C in a tunnel.
• the obscuring power of the smoke can be defined as the time during which the image of the extended source is partially or completely erased by the passage of this smoke between the camera and the extended source.
• the absorption coefficient A ⁇ (m ⁇ 1) is measured on two bands of wavelength from 7.65 to 13.2 ⁇ m and from 3.3 to 4.2 ⁇ m by application of Beer's law.
• compositions are produced by way of examples in the form of breads according to the preceding indications which are tested as specified above, at the same time as a reference composition described according to Example I of the FR-A patent. -2 560 186.
• compositions 1 and 2 are not sensitive to cracking. Similar results are obtained with compositions 3 and 4.
• the blackout power results from the color processing of a thermal image and is expressed in seconds.
• the absorption coefficient A ⁇ obtained thanks to the spectroradiometer, reflects the capacity of smoke to obscure for a very short time but is not representative of the anti-infrared power over time.
• composition 4 has excellent anti-infrared capacities. Its optimal density and low combustion speed make it suitable for producing large caliber smoke greater than 120 mm.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Botany (AREA)
• Pest Control & Pesticides (AREA)
• Plant Pathology (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Aiming, Guidance, Guns With A Light Source, Armor, Camouflage, And Targets (AREA)
• Air Bags (AREA)

Applications Claiming Priority (2)

Publications (2)

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Citations (5)

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• 1985
  • 1985-06-07 FR FR8508603A patent/FR2583037B1/fr not_active Expired
• 1986
  • 1986-05-13 NO NO861901A patent/NO164591C/no not_active IP Right Cessation
  • 1986-05-27 DE DE8686401123T patent/DE3660487D1/de not_active Expired
  • 1986-05-27 EP EP86401123A patent/EP0210082B1/de not_active Expired
  • 1986-06-03 US US06/869,894 patent/US4698108A/en not_active Expired - Lifetime
  • 1986-06-06 CA CA000511019A patent/CA1271334A/fr not_active Expired - Lifetime

Patent Citations (5)

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