Classifications

• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B23/00—Compositions characterised by non-explosive or non-thermic constituents
  • C06B23/04—Compositions characterised by non-explosive or non-thermic constituents for cooling the explosion gases including antifouling and flash suppressing agents
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B25/00—Compositions containing a nitrated organic compound
  • C06B25/18—Compositions containing a nitrated organic compound the compound being nitrocellulose present as 10% or more by weight of the total composition
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B25/00—Compositions containing a nitrated organic compound
  • C06B25/34—Compositions containing a nitrated organic compound the compound being a nitrated acyclic, alicyclic or heterocyclic amine
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B31/00—Compositions containing an inorganic nitrogen-oxygen salt
  • C06B31/02—Compositions containing an inorganic nitrogen-oxygen salt the salt being an alkali metal or an alkaline earth metal nitrate
  • C06B31/12—Compositions containing an inorganic nitrogen-oxygen salt the salt being an alkali metal or an alkaline earth metal nitrate with a nitrated organic compound
  • C06B31/22—Compositions containing an inorganic nitrogen-oxygen salt the salt being an alkali metal or an alkaline earth metal nitrate with a nitrated organic compound the compound being nitrocellulose
  • C06B31/24—Compositions containing an inorganic nitrogen-oxygen salt the salt being an alkali metal or an alkaline earth metal nitrate with a nitrated organic compound the compound being nitrocellulose with other explosive or thermic component
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B45/00—Compositions or products which are defined by structure or arrangement of component of product
  • C06B45/12—Compositions or products which are defined by structure or arrangement of component of product having contiguous layers or zones

Definitions

• the invention relates to a powder as propulsion powder or ignition powder for accelerating projectiles for mortar systems, which is based on nitrocellulose and comprises a crystalline, nitramine-based energetic material at 1-30 wt % and an inorganic muzzle flash suppressor, the powder being present in the form of grains, and the grains on their surface optionally having an inert plasticizing additive.
• the invention further relates to a method for producing such a powder.
• the Nitrochemie company recognized the signs of the times some while ago, and commenced development of a new generation of nitroglycerine-free high-performance powders, which showed no change in ballistic and chemical stability even in long deployments in hot climate zones—that is, their use and storage in hot climate zones posed absolutely no safety risk.
• This new powder generation was first developed specifically for high-power applications in medium-caliber barrel weapons, such as some subcaliber APFSDS-T munitions or full-caliber airburst munitions.
• Weapons systems of these kinds are typically equipped with relatively long barrels, and relatively high peak gas pressures occur on firing, typically of 3000-5000 bar.
• a powder as propulsion powder or ignition powder for accelerating projectiles for mortar systems, which is based on nitrocellulose.
• the powder comprises a crystalline, nitramine-based energetic material at 1-30 wt % and an inorganic muzzle flash suppressor at 0.1-10 wt %.
• the powder is present in the form of grains.
• the grains may have an inert plasticizing additive on their surface. This additive is present at not more than 1 wt %, i.e, in a range of 0-1 wt %.
• the grains preferably have an inert plasticizing additive on their surface at 0.01-1 wt %.
• the concentration is increased, the pressure profile steepens gradually, and at a level of addition of markedly more than 1 wt %, there is a significant increase in the pressure with increasing temperature.
• the increase in the muzzle velocity with increasing temperature is also relatively small, and so the propulsion system is distinguished overall by a largely neutral temperature characteristic. For certain applications, moreover, no inert plasticizing additive at all is needed.
• the powder of the invention exhibits a high degree of energetic conversion, leading to a high internal-ballistic performance capacity.
• Mortar systems are understood generally to be systems which have a relatively short tube and are fired at relatively steep angles. There are mortars ranging from a caliber of 37 mm (light mortars) up to 240 mm (ultra-heavy mortars). The most important among them are the heavy mortars in calibers of 60-120 mm. A particular focus of the invention is on the mortars or the corresponding propulsion systems for systems with calibers of 60 mm, 81 mm, and 120 mm.
• the powders of the invention may also be used as ignition powders for mortar applications.
• An ignition powder is mounted in the shaft of a mortar grenade and is needed to boost the impulse of the initial pyrotechnic detonation and to transmit it to the propulsion powder in the surrounding increments (horse shoes).
• the composition of an ignition powder is identical to the composition of a propulsion powder.
• the powders may differ in grain dimension and in grain geometry.
• Both the propulsion powder and the ignition powder are extrudable bulk powders which can be produced in a solvent process and comprise nitrocellulose as their main component.
• nitrocellulose has been the major starting material for the production of monobasic, diobasic, and tribasic propellent charge powders. It is obtained by nitration of cellulose (cotton linters), is available inexpensively in large quantities, and is offered with a large spectrum of different chemicophysical properties. Nitrocellulose varies, for example, in its nitrogen content, molecular weight, or viscosity, and on the basis of these differences can be processed to the different homogeneous propellent charge powder types. The energetic content of nitrocellulose is adjusted via the nitrogen content. In monobasic formulations, nitrocellulose is the sole energetic material, implying that the energy density of nitrocellulose is relatively high by comparison with other synthetic binder polymers.
• the present powders are based on nitrocellulose.
• the latter preferably has an average nitrogen content of 12.6%-13.25%.
• the further key components present in the grain matrix are a crystalline energetic material and also an inorganic muzzle flash suppressor.
• the crystalline energetic material raises the energetic content of the powder and is used at a concentration in the range of 1-30 wt %.
• the average distances between the individual crystals of the crystalline energetic material are sufficiently large that predominantly the individual crystals do not make contact.
• the shock pulse cannot be passed on from one crystal of explosive to the adjacently situated crystals. Accordingly, a primary-acting shock pulse is not multiplied and transmitted throughout the powder volume.
• the individual crystals considered statistically, are located too close together, and this results in a sharp rise in the vulnerability of the powder.
• the inorganic muzzle flash suppressor is used at a concentration in the range of 0.1-10 wt %. Adding an inorganic muzzle flash suppressor suppresses the reaction of uncombusted gases such as hydrogen or carbon monoxide in the region of the weapon muzzle, meaning that these gases do not ignite or ignite only to a much lesser extent. Accordingly, the muzzle flash is reduced, thereby on the one hand reducing the blinding effect of the fire on the gunner and also making it more difficult for the gunner to be located.
• the crystalline, nitramine-based energetic material preferably comprises at least one compound from the group encompassing hexogen (RDX) and octogen (HMX).
• RDX hexogen
• HMX octogen
• RDX crystalline energetic material
• HMX is more favorable and safe to produce.
• HMX is more expensive than RDX, but offers no particular advantages.
• Other nitramine compounds e.g., NIGU, etc.
• NIGU nitramine compounds
• akardite II active ingredients
• the crystalline nitramine compound has a defined average grain size.
• RDX preferably with an average grain size of 4-8 micrometers, more particularly 6 micrometers, is used.
• the homogeneous particle size of the crystalline energetic material permits powders to be produced that have relatively consistent chemical and ballistic properties.
• nitrate ester of the general formula R—O—NO 2 , for example, would also be conceivable. In comparison to nitramine compounds, though, nitrate esters are less chemically stable.
• nitramine compounds hexanitroisowurtzitane (CL-20, CAS -#14913-74-7), nitroguanidine (NIGU, NQ, CAS-#70-25-7, N-methylnitramine (tetryl, N-methyl-N,2,4,6-tetranitrobenzolamine, CAS-#479-45-8), and also nitrotriazolone (NTO, CAS#932-64-9) and triaminotrinitrobenzole (TATB, CAS#3058-38-6). All of these energetic compounds can be used individually or in combination with one another.
• the proportion of the crystalline energetic material is more preferably 5-25 wt %.
• the distances between the individual crystals of the energetic material are such that the vulnerability of the powder lies at a very low level.
• the use of an inert plasticizing additive may attenuate the vulnerability of the powder somewhat in the event of a relatively high weight proportion of the crystalline nitramine compound.
• RDX in addition to its property as a crystalline energetic material, RDX also has certain stabilizing properties, which are manifested from as little as around 1 wt % and which rise only insignificantly as the proportion increases.
• the inorganic muzzle flash suppressor preferably comprises at least one compound from the group of the alkali metal salts such as potassium nitrate and potassium sulfate, for example. As well as reducing muzzle flash, these compounds may also accelerate burn-off and thereby reduce the formation of residues, thereby further increasing the degree of energetic conversion.
• the inorganic muzzle flash suppressor is present in a proportion of 0.1-5 wt %.
• the inert plasticizing additive which may be located on the surface of the powder grain comprises, in particular, at least one compound from the group encompassing camphor, dialkyl phthalates (preferably di-(C8-C12) phthalates or hydrogenated derivatives thereof), and dialkyldiphenylureas (preferably diethyldiphenylurea, known under the trivial name centralite II).
• the inert plasticizing additive may also be applied as a combination of two or more individual compounds.
• the particularly preferred compound applied optionally to the surface of the powder grain is camphor.
• the surface of the powder grain is treated preferably with graphite and ethanol.
• the extruded powder grains are preferably subjected to a surface treatment with ethanol and graphite.
• the surface is treated with an inert plasticizing additive.
• the inert plasticizing additive penetrates the near-surface zones of the powder grain, where it remains—that is, it is localized and is not distributed in the grain matrix.
• the inert plasticizing additive has a depth of penetration of a few 100 micrometers, e.g., at most 400 micrometers, preferably 100-300 micrometers. This means that at least 95 wt % of the inert plasticizing additive is present down to that depth.
• the applied graphite remains preferably at the surface of the powder grain.
• the effect on the properties of the powder grain of the surface treatment i.e., of the application of ethanol and graphite and optionally of the inert plasticizing additive to the surface of the extruded powder grain, is positive.
• a temperature-neutral behavior and the bulk density i.e., the amount of powder that can fit within a given container volume
• the pressure level i.e., the ratio of peak gas pressure to muzzle velocity
• the grain matrix no longer necessarily includes inert compounds, and is able consequently to have the maximum possible amount of energetic compounds. The maximum effect can be achieved through a surface treatment with a combination of these substances.
• the inert plasticizing additive is more preferably present on the surface of the grain at not more than 0.1 wt %, i.e., at 0-0.1 wt %, more particularly in a range of 0.01-0.1 wt %.
• the change in the muzzle velocity and also the pressure increase on transition to high temperatures is relatively small.
• the possibility of achieving temperature-neutral behavior goes down.
• the grains for propulsion preferably have a circular-cylindrical geometry with lengthwise channels in the axial direction.
• the number of channels is arbitrary; a grain often has one channel, or 7 or 19 channels.
• a propellent charge powder of this kind, also called hole powder, is consequently pourable and free-flowable, and can therefore be filled industrially into cartridges.
• the length of the circular cylinder is in the range, for example, of 0.3-10 mm, and the diameter is in the range of 0.3-10 mm.
• the invention is configured as multihole powder
• preference is given to a geometry with a small pitch circle and therefore a relatively large outer wall thickness.
• the individual lengthwise channels are arranged more closely at the center and occupy overall a smaller pitch circle.
• six lengthwise channels in a 7-hole powder with a total cross section of about 3.6 mm form a pitch circle having a diameter of about 2.1 mm.
• the individual lengthwise channels of a propulsion powder have a hole diameter of 0.1-0.5 mm.
• the grain dimensions are typically smaller than in the context of propulsion applications. Moreover, they frequently have a circular-cylindrical geometry with a central lengthwise channel. They have, for example, an outside diameter of 1.3-1.7 mm, a length of 1.5-2.0 mm, an average wall thickness of 0.6-0.8 mm, and a hole diameter of about 0.10 mm.
• the material for the powders may be present in the form of strips or may be extruded directly into a defined form suitable for barrel weapons. In this form, it is particularly suitable for large-caliber munitions.
• This typically includes forms for which the width is much smaller (e.g., at least 5 times or at least 10 times) than the length, and the thickness in turn is much smaller (e.g., at least 5 times or at least 10 times) than the width.
• the thickness is, for example, 1-2 mm
• the width is, for example, 10 mm or more
• the length is, for example, 100-150 mm.
• shaped bodies i.e., hollow-cylindrical forms for a munition, where the sleeve is absent and/or is replaced by the shaped body arranged behind the ignition system.
• the grain matrix may optionally include further additions, known per se.
• additional additions known per se.
• sodium hydrogen carbonate CAS-#: 144-55-8
• calcium carbonate CAS-#: 471-34-1
• magnesium oxide CAS-#: 1309-48-4
• akardite II CAS-#: 724-18-5
• centralite I CAS-#: 90-93-7
• centralite II CAS-#: 611-92-7
• 2-nitrodiphenylamine CAS-#: 836-30-6) and diphenylamine (CAS-#: 122-39-4)
• Additives such as, for instance, lime, manganese oxide, magnesium oxide (CAS-#: 1303-48-4), molybdenum trioxide (CAS-#: 1313-27-5), magnesium silicate (CAS-#: 14807-96-6), calcium carbonate (CAS-#: 471-34-1), titanium dioxide (CAS-#: 13463-67-7), tungsten trioxide (CAS-#: 1314-35-8) serve for tube relief; compounds such as phthalic esters, citric esters, or adipic esters are customary plasticizers.
• the green grain in other words the powder still untreated per se, in the matrix may also include further known additions, for improving the ignition behavior and for modulating the burn-off behavior, for example.
• a method for producing a powder of the invention is distinguished by the fact that a solvent-containing powder dough based on nitrocellulose and on a crystalline, nitramine-based energetic material at 1-30 wt %, and on an inorganic muzzle flash suppressor is produced. Subsequently, a green grain is produced from this solvent-containing powder dough by extrusion. The solvent is removed from this green grain, and the green grain is optionally surface-treated with an inert plasticizing additive. Finally, the optionally surface-treated green grain is dried.
• a powder of the invention whose binder consists primarily of nitrocellulose and which additionally comprises a crystalline, nitramine-based energetic material and an inorganic muzzle flash suppressor can be produced on existing manufacturing plants.
• the solid components of the formulation can be admixed with a solvent mixture, for example.
• the resulting solvent-moist kneading dough can be kneaded in a kneeder and then extruded in a press to the desired geometry.
• the extrudates can be subjected to preliminary drying and cut to the desired grain length.
• the solvent may be withdrawn from the grain.
• the grain may then optionally be surface-treated with an inert plasticizing additive and/or subjected to a finishing operation.
• the green grain is preferably surface-treated with ethanol and graphite, i.e., graphitized.
• Graphitizing may be carried out as an individual method step. It is also possible, however, to apply graphite and ethanol together with the inert plasticizing additive to the green grain.
• the solvent is removed from the green grain by way of a humid air method.
• the green grain obtained by extrusion comprises an inorganic muzzle flash suppressor in the grain matrix.
• the green grain ought not to be subjected to a bath process, since otherwise the water-soluble inorganic muzzle flash suppressor would be washed out of the grain matrix.
• the solvent which has been used in the production process is therefore removed by means of humid air methods.
• the solvent-moist green grain has a stream of air passed through it for 10-60 hours, this stream of air being at temperatures between 20-70° C., being saturated with water vapor, and flowing at high rates of several hundred m 3 per hour.
• the proportion of the solvent is reduced to ⁇ 1%, while the water-soluble muzzle flash suppressor is not removed from the grain matrix, but instead remains therein.
• Finishing refers in particular to the careful drying and screening of the surface-treated grain.
• additions are added to the nitrocellulose-based powder dough; in order words, the additions are distributed uniformly within the matrix.
• the total amount of these additions is 0-10 wt % relative to the nitrocellulose, preferably 2-7 wt %.
• the total amount of the crystalline nitramine compound, which is typically RDX, is 0-30 wt % of the amount of nitrocellulose, preferably 0-20 wt %.
• the crystalline nitramine compound may have to be subjected to pre-treatment before it is added to the powder dough, in order to improve attachment to the matrix.
• the green grain is extruded through a die. Subsequently the water and the solvent are removed, preferably by means of humid air drying.
• the green grain is subjected to a surface treatment, in which, for example, optionally, an inert plasticizing additive and preferably further additives such as graphite, for example, are applied in the presence of ethanol (impregnation+coating).
• the extruded strands are briefly subjected to preliminary drying in air, then cut to the desired length, and the resulting green grain is laid out evenly on fine-mesh screens.
• the green grain thereafter is subjected for 30 hours to a water-saturated air flow of 200 m 3 /h and a temperature of 30° C. and subsequently for 30 hours to a 400 m 3 /h air flow and a temperature of 65° C. (humid air drying).
• 60 kg of the green grain heated to 60° C. are subsequently admixed, in a copper polishing drum heated to 55° C., with 0.05 wt % of graphite and 1.2 litres of ethanol, which are allowed to act thereafter for one hour with continual turning.
• the powder is spread out on metal sheets and dried at 60° C. for 24 hours.
• a powder dough according to example 1 is pressed through a die (i.e., extruded) with 7-hole geometry and 4.8 mm strand cross section.
• the extruded strands are briefly subjected to preliminary drying in air and cut to the desired length, and the resulting green grain is subjected to humid air drying (as described in example 1).
• 60 kg of the green grain are preheated to 60° C. and transferred into a copper polishing drum which is heated at 55° C.
• the green grain is admixed with 0.05% graphite and with a solution of 1 wt % of camphor in 1.2 kg of ethanol, and turned continually for one hour.
• the powder is spread out on metal sheets and dried at 60° C. for 24 hours.
• a powder dough according to example 1 is extruded through a die with 7-hole geometry and 5.1 mm strand cross section.
• the extruded strands are briefly subjected to preliminary drying in air and cut to the desired length, and the resulting green grain is subjected to humid air drying (as described in example 1).
• 120 kg of the green grain are preheated to 60° C. and transferred into a copper polishing drum which is heated at 55° C.
• the green grain is admixed with 0.05% of graphite and with a solution of 0.1 wt % of camphor in 2.4 kg of ethanol, and turned continually for one hour.
• the powder is spread out on metal sheets and dried at 60° C. for 24 hours.
• Example 3 shows that this is a powder having a better performance with a low temperature dependency. Moreover, the scatter in individual measurements is much less than for the other powders, pointing to a very homogeneous powder which is therefore consistent in its performance.
• a powder dough according to example 1 is pressed through a die (i.e. extruded) with 1-hole geometry and 2.1 mm strand cross section.
• the extruded strands are briefly subjected to preliminary drying in air and cut to the desired length, and the resulting green grain is subjected to humid air drying (as described in example 1).
• 20 kg of the green grain are preheated to 60° C. and transferred into a copper polishing drum which is heated at 55° C.
• the green grain is admixed with 0.3 wt % of graphite and with 0.3 kg of ethanol, after which it is left for one hour with continual turning.
• the powder is spread out on metal sheets and dried at 60° C. for 24 hours.
• a powder dough according to example 1 is pressed through a die (i.e. extruded) with 1-hole geometry and 2.1 mm strand cross section.
• the extruded strands are briefly subjected to preliminary drying in air and cut to the desired length, and the resulting green grain is subjected to humid air drying (as described in example 1).
• 20 kg of the green grain are preheated to 60° C. and transferred into a copper polishing drum which is heated at 55° C.
• the green grain is admixed with 0.3 wt % of graphite, 0.5 wt % of camphor, and 0.15 kg of ethanol, after which it is left therein for one hour with continual turning.
• the powder is spread out on metal sheets and dried at 60° C. for 24 hours.
• the nitrocellulose-containing powders of the invention as propulsion powders or ignition powders, which comprise a crystalline, nitramine-based energetic material and an inorganic muzzle flash suppressor, and which have small amounts of an inert plasticizing additive on the surface, are suitable for accelerating projectiles for mortar systems, at the same time exhibiting a temperature-independent behavior and therefore being suitable for use independently of climatic conditions.

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• 2013
  • 2013-01-29 KR KR1020157020466A patent/KR101944300B1/ko active IP Right Grant
  • 2013-01-29 US US14/760,643 patent/US20150321969A1/en not_active Abandoned
  • 2013-01-29 ES ES13704344T patent/ES2872299T3/es active Active
  • 2013-01-29 WO PCT/CH2013/000017 patent/WO2014117280A1/de active Application Filing
  • 2013-01-29 JP JP2015555513A patent/JP6165269B2/ja active Active
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