Classifications

• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06C—DETONATING OR PRIMING DEVICES; FUSES; CHEMICAL LIGHTERS; PYROPHORIC COMPOSITIONS
  • C06C7/00—Non-electric detonators; Blasting caps; Primers
• • 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
  • C06B23/006—Stabilisers (e.g. thermal stabilisers)
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B33/00—Compositions containing particulate metal, alloy, boron, silicon, selenium or tellurium with at least one oxygen supplying material which is either a metal oxide or a salt, organic or inorganic, capable of yielding a metal oxide

Definitions

• the present invention relates to percussion primer compositions for explosive systems, and to methods of making the same.
• Ignition devices rely on the sensitivity of the primary explosive that significantly limits available primary explosives.
• the most common lead styphnate alternative, diazodinitrophenol (DDNP or dinol) has been used for several decades relegated to training ammunition.
• DDNP-based primers suffer from poor reliability that may be attributed to low friction sensitivity, low flame temperature, and are hygroscopic.
• Metastable interstitial composites also known as metastable nanoenergetic composites (MNC) or superthermites
• MNC metastable nanoenergetic composites
• superthermites including Al/MoO 3 , AlAVO 3 ,
• Al/CuO and Al/Bi 2 2O 3 have been identified as potential substitutes for currently used lead styphnate. These materials have shown excellent performance characteristics, such as impact sensitivity and high temperature output. However, it has been found that these systems, despite their excellent performance characteristics, are difficult to process safely. The main difficulty is handling of dry nano-size powder mixtures due to their sensitivity to friction and electrostatic discharge (ESD). See U.S. Patent No..5717159 and U.S. Patent Publication No. 2006/0113014. .
• the present invention relates to a method of making a percussion primer or igniter, the method including providing at least one water wet explosive, combining at least one nano-size non-coated fuel particle having natural surface oxides thereon with at least one water wet explosive to form a first mixture and combining at least one oxidizer.
• the present invention relates to a method for preparing a percussion primer, the method including providing at least one water wet explosive, combining at least one sensitizer with the at least one water wet explosive, combining at least one nano-size non-coated fuel particle having natural surface oxides thereon with the at least one additional water wet explosive to form a wet mixture, dry blending at least one oxidizer and at least one binder to form a resultant dry blend and adding the dry blend to the water wet mixture and mixing until homogeneous to form a final mixture.
• the present invention relates to a percussion primer composition, the composition including at least one explosive, at least one nano-size non-coated fuel particle having natural surface oxides thereon and at least one oxidizer.
• the present invention relates to a percussion primer premixture, the premixture including at least one explosive, at least one nano-size non- coated fuel particle having surface oxides thereon and water in an amount of about 10 wt-% to about 40 wt-% of the premixture.
• the present invention relates to a primer composition including at least one explosive, at least one non-coated nano-size fuel particle having natural surface oxides thereon, a buffer system including at least one salt of citric acid and at least one salt of phosphoric acid and an oxidizer.
• the present invention relates to a gun cartridge including a casing, a secondary explosive disposed within the casing and a primary explosive disposed within the casing, the primary explosive including at least one primary energetic, at least one nano-size non-coated fuel particle having natural surface oxides thereon and at least one oxidizer.
• the present invention relates to a primer-containing ordinance assembly including a housing, a secondary explosive disposed within the housing and a primary explosive disposed within the housing, the primary explosive including at least one primary energetic, at least one nano-size non-coated fuel particle having natural surface oxides thereon; and at least one oxidizer.
• FIG. IA is a longitudinal cross-section of a rimfire gun cartridge employing a percussion primer composition of one embodiment of the invention.
• FIG. IB is an enlarged view of the anterior portion of the rimfire gun cartridge shown in FIG. IA.
• FIG. 2A a longitudinal cross-section of a centerfire gun cartridge employing a percussion primer composition of one embodiment of the invention.
• FIG. 2B is an enlarged view a portion of the centerfire gun cartridge of
• FIG. 2A that houses the percussion primer.
• FIG. 3 is a schematic illustration of exemplary ordnance in which a percussion primer of one embodiment of the invention is used.
• FIG. 4 is a simulated bulk autoignition temperature (SBAT) graph.
• FIG. 5 is an SBAT graph.
• FIG. 6 is an SBAT graph.
• FIG. 7 is an SBAT graph.
• the present invention relates to percussion primer compositions that include at least one energetic, at least one nano-size non-coated fuel particle having natural surface oxides thereon, and at least one oxidizer.
• a buffer or mixture of buffers may be employed.
• a sensitizer for increasing the sensitivity of the primary explosive is added to the primer compositions.
• the primer mixture according to one or more embodiments of the invention creates sufficient heat to allow for the use of moderately active metal oxides that are non-hygroscopic, non-toxic and non-corrosive.
• the primary energetic is suitably selected from energetics that are relatively insensitive to shock, friction and heat according to industry standards, making processing of these energetics more safe.
• Some of the relatively insensitive explosives that find utility herein for use as the primary explosive have been categorized generally as a secondary explosive due to their relative insensitivity.
• Examples of suitable classes of energetics include, but are not limited to, nitrate esters, nitramines, nitroaromatics and mixtures thereof.
• the energetics suitable for use herein include both primary and secondary energetics in these classes.
• nitramines include, but are not limited to, CL-20,
• RDX royal demolition explosive
• hexahydro-l,3,5-trinitro-l,3,5 triazine or l,3,5-trinitro-l,3,5-triazacyclohexane may also be referred to as cyclonite, hexagen, or cyclotrimethylenetrinitramine.
• HMX high melting explosive
• octahydro-l,3,5,7-tetranitro-l, 3,5,7- tetrazocine or l,3,5,7-tetranitro-l,3,5,7 tetraazacyclooctane (HMX) may also be referred to as cyclotetramethylene-tetranitramine or octagen, among other names.
• CL-20 is 2,4,6,8, 10,12-hexanitrohexaazaisowurtzitane (HNIW) or
• nitroaromatics include, but are not limited to, tetryl
• nitrate esters include, but are not limited to, PETN
• nitrocellulose is employed. Nitrocellulose, particularly nitrocellulose having a high percentage of nitrogen, for example, greater than about 10 wt-% nitrogen, and having a high surface area, has been found to increase sensitivity. In primers wherein the composition includes nitrocellulose, flame temperatures exceeding those of lead styphnate have been created. In some embodiments, the nitrocellulose has a nitrogen content of about 12.5-13.6% by weight and a particle size of 80-120 mesh.
• the primary explosive can be of varied particulate size.
• particle size may range from approximately 0.1 micron to about 100 microns. Blending of more than one size and type can be effectively used to adjust formulation sensitivity.
• the primary explosive is suitably employed in amounts of about 5% to about 40% by weight. This range may be varied depending on the primary explosive employed.
• suitable nano-size non-coated fuel particles include, but are not limited to, aluminum, boron, molybdenum, silicon, titanium, tungsten, magnesium, melamine, zirconium, calcium suicide, and mixtures thereof.
• the size of the fuel particle may vary from about 0.05 microns (50 nm) to about 0.120 microns (about 120 nm), and suitably about 70 nm to about 120 nm.
• the fuel particle has an average size of greater than 0.05 microns (50 nm), more suitably greater than about 0.070 microns (70 nm) and even more suitably has an average particle size of about 0.1 micron or about 100 nanometers.
• the present invention is not limited to this specific size of fuel particle, keeping the average size fuel particle above about 0.05 microns or 50 nanometers, can significantly improve the safety of processing due to the naturally occurring surface oxides and thicker oxide layer that exist on larger fuel particles. Smaller fuel particles may exhibit higher impact (friction) and shock sensitivities.
• Very small fuel particles such as those between about 20 nm and 50 nm, can be unsafe to handle. In the presence of oxygen they are prone to autoignition and are thus typically kept solvent wet or coated such as with polytetrafluoroethylene or an organic acid such as oleic acid.
• the fuel particles according to one or more embodiments of the invention have a natural oxide coating.
• Surface oxides reduce the sensitivity of the fuel particle, and reduce the need to provide any additional protective coating such as a fluoropolymer coating, e.g. polytetrafluoroethylene (PTFE), an organic acid coating or a phosphate based coating to reduce sensitivity and facilitate safe processing of the composition.
• PTFE polytetrafluoroethylene
• phosphate based coating to reduce sensitivity and facilitate safe processing of the composition.
• the natural oxide coating on nano-size particles having a larger average particle size i.e. those having a particle size of about 50 nm to about 120 nm, suitably those having a particle size of about 70 nm to about 120 nm, improves the stability of the particles, which consequently increases the margin of safety for processing and handling. Furthermore, a lower surface area may also decrease hazards while handling the nano-size fuel particles as risk of an electrostatic discharge initiation of the nano-size fuel particles decreases as the surface area decreases.
• coatings for the protection of the fuel particle may be eliminated due to the increased surface oxides on the larger fuel particles.
• a specific example of an aluminum fuel particle that may be employed herein is Alex® nano-aluminum powder having an average particle size of about 100 nanometers (0.1 microns) available from Argonide Nanomaterials in Pittsburgh, PA.
• the nano-size fuel particles are employed in amounts of about
• Buffers can be optionally added to the primer compositions to decrease the likelihood of hydrolysis of the fuel particles, which is dependent on both temperature and pH. While single acid buffers may be employed, the present inventors have found that a dual acid buffer system significantly increases the temperature stability of the percussion primer composition. Of course, more than two buffers may be employed as well. For example, it has been found that while a single acid buffer system can increase the temperature at which hydrolysis of the fuel particle occurs to about 120-140° F (about 49°C - 60°C), these temperatures are not sufficient for standard processing of percussion primers that includes oven drying. Therefore, higher hydrolysis onset temperatures are desirable for safe oven drying of the percussion primer compositions.
• any buffer may be suitably employed herein, it has been found that some buffers are more effective than others for reducing the temperature of onset of hydrolysis.
• an organic acid and a phosphate salt are employed. More specifically, in some embodiments, a combination of citrate and phosphate are employed. In weakly basic conditions, the dibasic phosphate ion (HPO 4 ⁇ ) and the tribasic citrate ion (C 6 HsO 7 " ) are prevalent. In weakly acid conditions, the monobasic phosphate ion (H 2 PO 4 " ) and the dibasic citrate ion (COH 6 O 7 2" ) are most prevalent.
• the stability of explosives to both moisture and temperature is desirable for safe handling of firearms.
• small cartridges are subject to ambient conditions including temperature fluctuations and moisture, and propellants contain small amounts of moisture and volatiles. It is desirable that these loaded rounds are stable for decades, be stable for decades over a wide range of environmental conditions of fluctuating moisture and temperatures.
• primer compositions according to one or more embodiments of the invention can be safely stored water wet (25%) for long periods without any measurable affect on the primer sensitivity or ignition capability. In some embodiments, the primer compositions may be safely stored for at least about 5 weeks without any measurable affect on primer sensitivity or ignition capability.
• the aluminum contained in the percussion primer compositions according to one or more embodiments of the invention exhibit no exotherms during simulated bulk autoignition tests (SBAT) at temperatures greater than about 200° F (about 93° C), and even greater than about 225° F (about 107° C) when tested as a slurry in water.
• additional fuels may be added.
• a sensitizer may be added to the percussion primer compositions according to one or more embodiments of the invention. As the particle size of the nano-size fuel particles increases, sensitivity decreases. Thus, a sensitizer may be beneficial. Sensitizers may be employed in amounts of 0% to about 20%, suitably 0% to about 15% by weight and more suitably 0% to about 10% by weight of the composition. One example of a suitable sensitizer includes, but is not limited to, tetracene. [0057] The sensitizer may be employed in combination with a friction generator.
• Friction generators are useful in amounts of about 0% to about 25% by weight of the primer composition.
• a suitable friction generator includes, but is not limited to, glass powder.
• Tetracene is suitably employed as a sensitizing explosive while glass powder is employed as a friction generator.
• Oxidizers may be employed in amounts of about 20% to about 70% by weight of the primer composition.
• the oxidizers employed herein are moderately active metal oxides, and are non-hygroscopic and are not considered toxic. Examples of oxidizers include, but are not limited to, bismuth oxide, bismuth subnitrate, bismuth tetroxide, bismuth sulfide, zinc peroxide, tin oxide, manganese dioxide, molybdenum trioxide, and combinations thereof.
• Other conventional primer additives such as binders may be employed in the primer compositions herein as is known in the art.
• binders Both natural and synthetic binders find utility herein.
• suitable binders include, but are not limited to, natural and synthetic gums including xanthan, Arabic, tragacanth, guar, karaya, and synthetic polymeric binders such as hydroxypropylcellulose and polypropylene oxide, as well as mixtures thereof. See also U.S. Patent Publication No. 2006/0219341 Al, the entire content of which is incorporated by reference herein.
• Binders may be added in amounts of about 0.1 wt% to about 5 wt-% of the composition, and more suitably about 0.1 wt% to about 1 wt% of the composition.
• compositions according to one or more embodiments of the invention may also be employed in the compositions according to one or more embodiments of the invention.
• inert fillers, diluents, other binders, low out put explosives, etc. may be optionally added.
• the above lists and ranges are intended for illustrative purposes only, and are not intended as a limitation on the scope of the present invention.
• the primer compositions according to one or more embodiments of the invention may be processed using simple water processing techniques.
• the present invention allows the use of larger fuel particles which are safer for handling while maintaining the sensitivity of the assembled primer. It is surmised that this may be attributed to the use of larger fuel particles and/or the dual buffer system.
• the steps of milling and sieving employed for MIC-MNC formulations may also be eliminated. For at least these reasons, processing of the primer compositions according to the invention is safer.
• the method of making the primer compositions according to one or more embodiments of the invention generally includes mixing the primary explosive water wet with at least one nano-size non-coated fuel particle having natural surface oxides thereon to form a first mixture, and adding an oxidizer to the first mixture.
• the oxidizer may be optionally dry blended with at least one binder to form a second dry mixture, and the second mixture then added to the first mixture and mixing until homogeneous to form a final mixture.
• water-wet shall refer to a water content of between about 10 wt-% and about 40 wt-%, more suitably about 18% to about 30% and most suitably about 25% by weight.
• the sensitizer may be added either to the water wet primary explosive, or to the primary explosive/nano-size non-coated fuel particle water wet blend.
• the sensitizer may optionally further include a friction generator such as glass powder.
• At least one buffer may be added to the process to keep the system acidic and to prevent significant hydrogen evolution and further oxides from forming.
• a mildly acidic buffer having a pH in the range of about 4-8, suitably 4-7, can help to prevent such hydrolysis. While at a pH of 8, hydrolysis is delayed, by lowering the pH, hydrolysis can be effectively stopped, thus, a pH range of 4-7 is preferable.
• the buffer solution is suitably added as increased moisture to the primary explosive prior to addition of the non-coated nano-size fuel particle.
• the nano-size fuel particle may be preimmersed in the buffer solution to further increase handling safety.
• nano-size fuel particles and the explosive can be water-mixed according to one or more embodiments of the invention, maintaining conventional mix methods and associated safety practices.
• primary oxidizer-fuel formulations when blended with fuels, sensitizers and binders, can be substituted in applications where traditional lead styphnate and diazodinitrophenol (DDNP) primers and igniter formulations are employed.
• DDNP diazodinitrophenol
• the heat output of the system is sufficient to utilize non-toxic metal oxidizers of higher activation energy typically employed but under utilized in lower flame temperature DDNP based formulations.
• Additional benefits of the present invention include improved stability, increased ignition capability, improved ignition reliability, lower final mix cost, and increased safety due to the elimination of lead styphnate production and handling.
• the present invention finds utility in any igniter or percussion primer application where lead styphnate is currently employed.
• the percussion primer according to the present invention may be employed for small caliber and medium caliber cartridges, as well as industrial powerloads.
• compositions and concentration ranges for a variety of different cartridges. Such compositions and concentration ranges are for illustrative purposes only, and are not intended as a limitation on the scope of the present invention.
• the nitrocellulose is 30-100 mesh and 12.5-13.6 wt-% nitrogen.
• the nano-aluminum is sold under the tradename of Alex® and has an average particles size of 0.1 microns.
• the additional aluminum fuel is 80-120 mesh.
• Table 1 Illustrative percussion primer compositions for pistol/small rifle.
• Table 2 Illustrative percussion primer compositions for large rifle.
• Table 3 Illustrative percussion primer compositions for industrial/commercial power load rimfire.
• Table 4 Illustrative percussion primer compositions for industrial commercial power load rimfire.
• Table 5 Illustrative percussion primer compositions for industrial/commercial rimfire.
• Table 6 Illustrative percussion primer compositions for industrial/commercial shotshell.
• the percussion primer is used in a centerfire gun cartridge or in a rimfire gun cartridge.
• a centerfire gun cartridge or in a rimfire gun cartridge.
• a rimfire gun cartridge In small arms using the rimfire gun cartridge, a
• firing pin strikes a rim of a casing of the gun cartridge.
• firing pin of small arms using the centerfire gun cartridge strikes a metal cup in the center of the cartridge
• the firing pin may produce a percussive event that is sufficient to detonate the percussion primer in the rimfire gun cartridge or in the centerfire gun cartridge, causing the secondary explosive composition to ignite.
• FIG. IA is a longitudinal cross-section of a rimfire gun cartridge shown generally at 6.
• Cartridge 6 includes a housing 4.
• Percussion primer 2 may be substantially evenly distributed around an interior volume defined by a rim portion 3 of casing 4 of the cartridge 6 as shown in FIG. IB which is an enlarged view of an anterior portion of the rimfire gun cartridge 6 shown in FIG. IA.
• FIG. 2A is a longitudinal cross-sectional view of a centerfire gun cartridge shown generally at 8.
• the percussion primer 2 may be positioned in an aperture 10 in the casing 4.
• FIG. 2B is an enlarged view of aperture 10 in FIG. 2 A more clearly showing primer 2 in aperture 10.
• the propellant composition 12 may be positioned substantially adjacent to the percussion primer 2 in the rimfire gun cartridge 6 or in the centerfire gun cartridge 8.
• the percussion primer 2 When ignited or combusted, the percussion primer 2 may produce sufficient heat and condensing of hot particles to ignite the propellant composition 12 to propel projectile 16 from the barrel of the firearm or larger caliber ordnance (such as, without limitation, handgun, rifle, automatic rifle, machine gun, any small and medium caliber cartridge, automatic cannon, etc.) in which the cartridge 6 or 8 is disposed.
• the combustion products of the percussion primer 2 may be environmentally friendly, noncorrosive, and nonabrasive
• the percussion primer 2 may also be used in larger ordnance, such as (without limitation) grenades, mortars, or detcord initiators, or to initiate mortar rounds, rocket motors, or other systems including a secondary explosive, alone or in combination with a propellant, all of the foregoing assemblies being encompassed by the term "primer-containing ordnance assembly," for the sake of convenience.
• the percussion primer 2 may be positioned substantially adjacent to a secondary explosive composition 12 in a housing 18, as shown in FIG. 3.
• SBAT Simple acidic buffers provided some protection of nano- aluminum particles.
• specific dual buffer systems exhibited significantly
• FIG. 4 is an SBAT graph illustrating the temperature at which hydrolysis begins when Alex® aluminum particles are mixed in water with no buffer.
• the hydrolysis onset temperature is 118° F (47.8° C). See no. 1 in table 7.
• FIG. 5 is an SBAT graph illustrating the temperature at which hydrolysis begins using only a single buffer which is citrate.
• the hydrolysis onset temperature is
• FIG. 6 is an SBAT graph illustrating the temperature at which hydrolysis begins using only a single buffer which is a phosphate buffer.
• the hydrolysis onset temperature is 129° F (53.9° C).
• FIG. 7 is an SBAT graph illustrating the temperature at which hydrolysis begins using a dual citrate/phosphate buffer system. Hydrolysis has been effectively stopped at a pH of 5.0 even at temperatures of well over 200° F (about 93° C).
• the present invention finds utility in any application where lead styphnate based igniters or percussion primers are employed.
• Such applications typically include an igniter or percussion primer, a secondary explosive, and for some applications, a propellant.

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