U.S. patent application number 11/093633 was filed with the patent office on 2006-10-05 for heavy metal free, environmentally green percussion primer and ordnance and systems incorporating same.
Invention is credited to Reed J. Blau, Harold E. Johnston, Scott K. Lusk, Kirstin F. Warner.
Application Number | 20060219341 11/093633 |
Document ID | / |
Family ID | 36693212 |
Filed Date | 2006-10-05 |
United States Patent
Application |
20060219341 |
Kind Code |
A1 |
Johnston; Harold E. ; et
al. |
October 5, 2006 |
Heavy metal free, environmentally green percussion primer and
ordnance and systems incorporating same
Abstract
A sensitized explosive that comprises an explosive precipitated
onto a sensitizer. The explosive is CL-20, PETN, RDX, HMX, or
mixtures thereof and the sensitizer is aluminum, titanium,
zirconium, magnesium, melamine, styrene, lithium aluminum hydride,
or mixtures thereof. The sensitized explosive is used in a
percussion primer that includes a bismuth compound and a melt
binder. The bismuth compound is bismuth oxide, bismuth subnitrate,
bismuth tetroxide, bismuth sulfide, or mixtures thereof and the
melt binder is a wax having a melting point above ambient
temperature, trinitrotoluene, poly(3,3-bis(azidomethyl)oxetane),
poly(3-azidomethyl-3-methyloxetane), ethyl-3,5-dinitrobenzoate, or
mixtures thereof. A gun cartridge and other primer-containing
ordnance assemblies employing the percussion primer are also
disclosed. Methods of forming the sensitized explosive and the
percussion primer are also disclosed.
Inventors: |
Johnston; Harold E.;
(Brigham City, UT) ; Warner; Kirstin F.; (Ogden,
UT) ; Blau; Reed J.; (Richmond, UT) ; Lusk;
Scott K.; (Clarkston, UT) |
Correspondence
Address: |
TRASKBRITT, P.C.
P.O. BOX 2550
SALT LAKE CITY
UT
84110
US
|
Family ID: |
36693212 |
Appl. No.: |
11/093633 |
Filed: |
March 30, 2005 |
Current U.S.
Class: |
149/46 |
Current CPC
Class: |
C06B 33/08 20130101;
C06B 45/24 20130101; F42C 19/10 20130101; F42C 19/0803 20130101;
C06B 45/00 20130101; C06B 45/34 20130101; C06B 45/18 20130101; C06C
7/00 20130101 |
Class at
Publication: |
149/046 |
International
Class: |
C06B 31/28 20060101
C06B031/28 |
Claims
1. A sensitized explosive comprising an explosive selected from the
group consisting of
2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo[5.5.0.0.sup.5,90.-
sup.3,11]-dodecane ("CL-20"), pentaerythritol tetranitrate
("PETN"), cyclo-1,3,5-trimethylene-2,4,6-trinitramine ("RDX"),
cyclotetramethylene tetranitramine ("HMX"), and mixtures thereof
and a sensitizer selected from the group consisting of aluminum,
aluminum oxide, titanium, zirconium, magnesium, boron, silicon,
melamine, styrene, lithium aluminum hydride, calcium silicide, and
mixtures thereof, wherein the explosive is precipitated onto the
sensitizer.
2. The sensitized explosive of claim 1, wherein the sensitized
explosive has an average particle size that ranges from
approximately 1 .mu.m to approximately 100 .mu.m.
3. The sensitized explosive of claim 1, wherein the explosive
comprises from approximately 70% by weight to approximately 99.5%
by weight of a total weight of the sensitized explosive and the
sensitizer comprises from approximately 0.5% by weight to
approximately 30% by weight of the total weight of the sensitized
explosive.
4. A percussion primer comprising a sensitized explosive, a bismuth
compound, and a melt binder, wherein the sensitized explosive
comprises an explosive precipitated onto a sensitizer.
5. The percussion primer of claim 4, wherein the explosive has an
impact sensitivity that ranges from approximately 0.3 kp m to
approximately 0.75 kp m.
6. The percussion primer of claim 4, wherein the explosive is
selected from the group consisting of
2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo[5.5.0.0.sup.5,90.-
sup.3,11]-dodecane ("CL-20"), pentaerythritol tetranitrate
("PETN"), cyclo-1,3,5-trimethylene-2,4,6-trinitramine ("RDX"),
cyclotetramethylene tetranitramine ("HMX"), and mixtures
thereof.
7. The percussion primer of claim 4, wherein the sensitizer is
selected from the group consisting of aluminum, aluminum oxide,
titanium, zirconium, magnesium, boron, silicon, melamine, styrene,
lithium aluminum hydride, calcium silicide, and mixtures
thereof.
8. The percussion primer of claim 4, wherein the sensitizer has a
particle size that ranges from approximately 0.1 .mu.m to
approximately 100 .mu.m.
9. The percussion primer of claim 4, wherein the sensitizer has a
particle size that ranges from approximately 100 nm to
approximately 600 nm.
10. The percussion primer of claim 4, wherein the sensitizer has a
particle size that ranges from approximately 2 .mu.m to
approximately 5 .mu.m.
11. The percussion primer of claim 4, wherein the explosive
comprises from approximately 70% by weight to approximately 99.5%
by weight of a total weight of the sensitized explosive and the
sensitizer comprises from approximately 0.5% by weight to
approximately 30% by weight of the total weight of the sensitized
explosive.
12. The percussion primer of claim 4, wherein the bismuth compound
comprises bismuth oxide, bismuth subnitrate, bismuth tetroxide,
bismuth sulfide, or mixtures thereof.
13. The percussion primer of claim 4, wherein the melt binder
comprises a wax having a melting point above ambient temperature,
trinitrotoluene, poly(3,3-bis(azidomethyl)oxetane),
poly(3-azidomethyl-3-methyloxetane), ethyl-3,5-dinitrobenzoate,
1,3,3-trinitroazetine, natural gums, or mixtures thereof.
14. The percussion primer of claim 4, wherein the sensitized
explosive comprises from approximately 35% by weight to
approximately 55% by weight of a total weight of the percussion
primer, the bismuth compound comprises from approximately 20% by
weight to approximately 75% by weight of the total weight of the
percussion primer, and the melt binder comprises from approximately
0.5% by weight to less than approximately 20% by weight of the
total weight of the percussion primer.
15. The percussion primer of claim 4, further comprising at least
one of ground glass, nitrocellulose, and tetracene.
16. A percussion primer, comprising: a sensitized explosive
comprising an explosive selected from the group consisting of
2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo[5.5.0.0.sup.5,90.-
sup.3,11]-dodecane ("CL-20"), pentaerythritol tetranitrate
("PETN"), cyclo-1,3,5-trimethylene-2,4,6-trinitramine ("RDX"), and
cyclotetramethylene tetranitramine ("HMX") and a sensitizer
selected from the group consisting of aluminum and melamine; a
bismuth compound selected from the group consisting of bismuth
oxide, bismuth subnitrate, bismuth tetroxide, bismuth sulfide, and
mixtures thereof; and a melt binder selected from the group
consisting of a wax having a melting point above ambient
temperature, trinitrotoluene, poly(3,3-bis(azidomethyl)oxetane),
poly(3-azidomethyl-3-methyloxetane), ethyl-3,5-dinitrobenzoate,
1,3,3-trinitroazetine, natural gums, and mixtures thereof.
17. The percussion primer of claim 16, wherein the sensitized
explosive comprises from approximately 35% by weight to
approximately 55% by weight of a total weight of the percussion
primer, the bismuth compound comprises from approximately 20% by
weight to approximately 75% by weight of the total weight of the
percussion primer, and the melt binder comprises from approximately
0.5% by weight to less than approximately 20% by weight of the
total weight of the percussion primer.
18. The percussion primer of claim 16, further comprising at least
one of ground glass, nitrocellulose, and tetracene.
19. A method of preparing a sensitized explosive, comprising:
precipitating an explosive onto a sensitizer, wherein the explosive
is selected from the group consisting of
2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo[5.5.0.0.sup.5,90.-
sup.3,11]-dodecane ("CL-20"), pentaerythritol tetranitrate
("PETN"), cyclo-1,3,5-trimethylene-2,4,6-trinitramine ("RDX"), and
cyclotetramethylene tetranitramine ("HMX") and the sensitizer is
selected from the group consisting of aluminum, aluminum oxide,
titanium, zirconium, magnesium, boron, silicon, melamine, styrene,
lithium aluminum hydride, calcium silicide, and mixtures
thereof.
20. The method of claim 19, wherein precipitating an explosive onto
a sensitizer comprises dissolving the explosive in a solvent,
adding the sensitizer to the solvent, and removing the solvent.
21. The method of claim 20, wherein dissolving the explosive in a
solvent comprises dissolving the explosive in a polar organic
solvent selected from the group consisting of ethyl acetate,
acetone, and mixtures thereof.
22. The method of claim 20, wherein removing the solvent comprises
forming crystals of the sensitized explosive.
23. The method of claim 22, wherein forming crystals of the
sensitized explosive comprises forming crystals of the sensitized
explosive having an average particle size that ranges from
approximately 1.0 .mu.m to approximately 100 .mu.m.
24. A method of forming a percussion primer, comprising: providing
a sensitized explosive that comprises an explosive precipitated
onto a sensitizer; and combining the sensitized explosive with a
bismuth compound and a melt binder.
25. The method of claim 24, wherein providing a sensitized
explosive that comprises an explosive precipitated onto a
sensitizer comprises dissolving the explosive in a solvent, adding
the sensitizer to the solvent, and removing the solvent.
26. The method of claim 25, wherein dissolving the explosive in a
solvent comprises dissolving the explosive in a nonpolar, organic
solvent selected from the group consisting of ethyl acetate,
acetone, and mixtures thereof.
27. The method of claim 24, wherein removing the solvent comprises
forming crystals of the sensitized explosive.
28. The method of claim 24, wherein combining the sensitized
explosive with a bismuth compound and a melt binder comprises
combining the sensitized explosive with a bismuth compound selected
from the group consisting of bismuth oxide, bismuth subnitrate,
bismuth tetroxide, bismuth sulfide, and mixtures thereof.
29. The method of claim 24, wherein combining the sensitized
explosive with a bismuth compound and a melt binder comprises
combining the sensitized explosive with a melt binder selected from
the group consisting of a wax having a melting point above ambient
temperature, trinitrotoluene, poly(3,3-bis(azidomethyl)oxetane),
poly(3-azidomethyl-3-methyloxetane), ethyl-3,5-dinitrobenzoate,
1,3,3-trinitroazetine, natural gums, and mixtures thereof.
30. A gun cartridge comprising: a casing housing a percussion
primer and a secondary explosive composition, wherein the
percussion primer comprises a sensitized explosive, a bismuth
compound, and a melt binder, the sensitized explosive comprising an
explosive precipitated onto a sensitizer; and a projectile disposed
in a mouth of the casing.
31. The gun cartridge of claim 30, wherein the explosive is
selected from the group consisting of
2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo[5.5.0.0.sup.5,90.-
sup.3,11]-dodecane ("CL-20"), pentaerythritol tetranitrate
("PETN"), cyclo-1,3,5-trimethylene-2,4,6-trinitramine ("RDX"),
cyclotetramethylene tetranitramine ("HMX"), and mixtures thereof
and the sensitizer is selected from the group consisting of
aluminum, aluminum oxide, titanium, zirconium, magnesium, boron,
silicon, melamine, styrene, lithium aluminum hydride, calcium
silicide, and mixtures thereof.
32. The gun cartridge of claim 30, wherein the bismuth compound
comprises bismuth oxide, bismuth subnitrate, bismuth tetroxide, or
mixtures thereof and the melt binder comprises a wax having a
melting point above ambient temperature, trinitrotoluene,
poly(3,3-bis(azidomethyl)oxetane),
poly(3-azidomethyl-3-methyloxetane), ethyl-3,5-dinitrobenzoate,
1,3,3-trinitroazetine, natural gums, or mixtures thereof.
33. The gun cartridge of claim 30, wherein the gun cartridge
comprises a centerfire gun cartridge.
34. The gun cartridge of claim 30, wherein the gun cartridge
comprises a rimfire gun cartridge.
35. A primer-containing ordnance assembly, comprising: a housing
comprising a percussion primer and at least a secondary explosive
composition, wherein the percussion primer comprises a sensitized
explosive, a bismuth compound, and a melt binder, the sensitized
explosive comprising an explosive precipitated onto a
sensitizer.
36. The ordnance of claim 35, wherein the explosive is selected
from the group consisting of
2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo[5.5.0.0.sup.5,90.-
sup.3,11]-dodecane ("CL-20"), pentaerythritol tetranitrate
("PETN"), cyclo-1,3,5-trimethylene-2,4,6-trinitramine ("RDX"),
cyclotetramethylene tetranitramine ("HMX"), and mixtures thereof
and the sensitizer is selected from the group consisting of
aluminum, aluminum oxide, titanium, zirconium, magnesium, boron,
silicon, melamine, styrene, lithium aluminum hydride, calcium
silicide, and mixtures thereof.
37. The ordnance of claim 35, wherein the bismuth compound
comprises bismuth oxide, bismuth subnitrate, bismuth tetroxide,
bismuth sulfide, or mixtures thereof and the melt binder comprises
a wax having a melting point above ambient temperature,
trinitrotoluene, poly(3,3-bis(azidomethyl)oxetane),
poly(3-azidomethyl-3-methyloxetane), ethyl-3,5-dinitrobenzoate,
1,3,3-trinitroazetine, natural gums, or mixtures thereof.
38. The ordnance of claim 35, wherein the ordnance comprises a
grenade, mortar, detcord initiator, mortar round, or rocket motor.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a percussion primer that is
nontoxic, noncorrosive, and nonhygroscopic. More specifically, the
present invention relates to a percussion primer that includes a
sensitized explosive, an oxidizer, and a melt binder, as well as to
ordnance and systems incorporating such a percussion primer.
BACKGROUND OF THE INVENTION
[0002] A percussion primer is a primary explosive composition that
is commonly used to ignite a secondary explosive composition or
charge. The primary explosive composition is more sensitive to
impact than the secondary explosive composition and burns or
deflagrates for a short period of time before detonating. To be
effective as a percussion primer, the primary explosive composition
must have a relatively low activation energy for a given output
energy. In contrast, conventional explosives and insensitive
explosives with similar output energies have higher activation
energies. Since the primary explosive composition is more sensitive
to impact, the primary explosive composition ignites and detonates
before the secondary explosive composition. In contrast, the
secondary explosive composition is relatively stable and does not
detonate until initiated by the primary explosive composition.
[0003] Many ingredients of conventional percussion primers are
toxic and their use is restricted by the Environmental Protection
Agency. These ingredients include styphnate and picrate salts,
heavy metal compounds, or diazodinitrophenol ("DDNP" or dinol). The
heavy metal compounds include compounds of mercury, lead, barium,
antimony, beryllium, cesium, cadmium, arsenic, chromium, selenium,
strontium, tin, or thallium, such as lead styphnate or barium
styphnate, or mercury fulminate. Upon ignition, a percussion primer
that includes one of these ingredients emits toxic lead oxides or
toxic compounds of other heavy metals, such as oxides of cesium,
barium, antimony, or strontium. DDNP is also toxic because it is
known to cause allergic reactions and is possibly carcinogenic.
[0004] Conventional percussion primers also commonly include
oxidizers, such as potassium nitrate, potassium perchlorate, or
potassium chlorate, which are also toxic. Potassium nitrate and
potassium chlorate are also hygroscopic, which increases the
complexity of processing the percussion primer because the
potassium nitrate and potassium chlorate must be stored in ovens
and cannot be used on wet days. In addition to requiring
specialized storage, hygroscopic materials cause the percussion
primer to have a sticky consistency, which affects loading and
processing of the percussion primer. Other hygroscopic ingredients,
such as gums, are also used in conventional percussion primers.
Gums typically gain about 30% of the gum weight in moisture when
exposed to humid conditions. In addition to being hygroscopic, gums
are obtained from natural sources and, therefore, exhibit
characteristics which may vary from batch to batch. Some
ingredients of conventional percussion primers are also corrosive,
such as potassium chlorate, which is corrosive to steel and
corrodes a gun barrel when the percussion primer is used in small
arms ammunition.
[0005] To reduce health and environmental risks, percussion primers
that are free of lead have been developed. U.S. Pat. No. 4,522,665
to Yates, Jr. et al. discloses a percussion primer that includes
titanium and potassium perchlorate. U.S. Pat. No. 5,417,160 to Mei
et al. discloses a percussion primer that contains calcium
silicide, DDNP, and an alkaline or alkaline earth nitrate. U.S.
Pat. No. 5,167,736 to Mei et al. discloses a percussion primer that
includes DDNP and boron and U.S. Pat. No. 5,567,252 to Mei et al.
discloses a percussion primer that includes DDNP, boron, and iron
oxide. U.S. Pat. Nos. 4,963,201 and 5,216,199 to Bjerke et al.
disclose a percussion primer that includes DDNP, strontium nitrate,
tetracene, and a nitrate ester fuel. U.S. Pat. No. 6,478,903 to
John, Jr. et al. discloses a percussion primer that includes
bismuth sulfide and potassium nitrate or zinc sulfide and aluminum
nitrate. U.S. Pat. No. 4,581,082 to Hagel et al. discloses a primer
charge that includes zinc peroxide, DDNP, and/or a strontium salt
of mono- and/or dinitrodihydroxydiazobenzene.
[0006] International Application WO 01/21558 to Nesveda et al.
discloses an ignition mixture that includes a high explosive and a
sensibilizer, such as tetracene, tetrazole, a tetrazole derivative,
or a tetrazole salt. The high explosive is a nitroester, such as
penthrite, nitrocellulose, or hexanitromanite, or a nitramine, such
as hexogen ("RDX"), octogen ("HMX"), or tetryl. The ignition
mixture also includes powdered boron as a fuel and an oxidizing
agent, such as an oxide of copper, bismuth, zinc, iron, manganese,
vanadium, tin, molybdenum, or calcium.
[0007] In light of the problems mentioned above with conventional
percussion primers, it would be desirable to produce a percussion
primer that utilizes nontoxic, noncorrosive, and nonhygroscopic
ingredients.
BRIEF SUMMARY OF THE INVENTION
[0008] The present invention relates to a sensitized explosive that
comprises an explosive precipitated onto a sensitizer. The
explosive is selected from the group consisting of
2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo[5.5.0.0.sup.5,90.-
sup.3,11]-dodecane ("CL-20"), pentaerythritol tetranitrate
("PETN"), cyclo-1,3,5-trimethylene-2,4,6-trinitramine ("RDX"),
cyclotetramethylene tetranitramine ("HMX"), and mixtures thereof.
The sensitizer is selected from the group consisting of aluminum,
aluminum oxide, titanium, zirconium, magnesium, boron, silicon,
melamine, styrene, lithium aluminum hydride, calcium silicide, and
mixtures thereof. The explosive may comprise from approximately 70%
by weight ("wt %") to approximately 99.5 wt % of a total weight of
the sensitized explosive and the sensitizer may comprise from
approximately 0.5 wt % to approximately 30 wt % of the total weight
of the sensitized explosive. The sensitized explosive may have a
particle size that ranges from approximately 1 .mu.m to
approximately 100 .mu.m.
[0009] The present invention also relates to a percussion primer
that comprises a sensitized explosive, a bismuth compound, and a
melt binder, wherein the sensitized explosive comprises an
explosive precipitated onto a sensitizer. The explosive may have an
impact sensitivity that ranges from approximately 0.3 kp m to
approximately 0.75 kp m. The explosive and the sensitizer may be
one of the compounds previously described and may be present in the
amounts indicated above. The bismuth compound may be bismuth oxide,
bismuth subnitrate, bismuth tetroxide, bismuth sulfide, or mixtures
thereof. The melt binder may be a wax having a melting point above
ambient temperature, trinitrotoluene,
poly(3,3-bis(azidomethyl)oxetane),
poly(3-azidomethyl-3-methyloxetane), ethyl-3,5-dinitrobenzoate,
1,3,3-trinitroazetine, natural gums, or mixtures thereof.
[0010] The sensitized explosive may comprise from approximately 35
wt % to approximately 55 wt % of a total weight of the percussion
primer, the bismuth compound may comprise from approximately 20 wt
% to approximately 75 wt % of the total weight of the percussion
primer, and the melt binder may comprise from approximately 0.5 wt
% to less than approximately 20 wt % of the total weight of the
percussion primer. The percussion primer may further comprise at
least one of ground glass, nitrocellulose, and tetracene.
[0011] The present invention also relates to a method of producing
the sensitized explosive that comprises precipitating an explosive
onto a sensitizer. The explosive is selected from the group
consisting of CL-20, PETN, RDX, and HMX and the sensitizer is
selected from the group consisting of aluminum, aluminum oxide,
titanium, zirconium, magnesium, boron, silicon, melamine, styrene,
lithium aluminum hydride, calcium silicide, and mixtures thereof.
To precipitate the explosive, the explosive may be dissolved in a
solvent, the sensitizer added to the solvent, and the solvent
removed, forming crystals of the sensitized explosive. The crystals
may have a particle size that ranges from approximately 1.0 .mu.m
to approximately 100 .mu.m.
[0012] The present invention also relates to a method of producing
the percussion primer that comprises providing a sensitized
explosive and combining the sensitized explosive with a bismuth
compound and a melt binder. The sensitized explosive is produced as
described above. The bismuth compound and the melt binder are as
described above.
[0013] The present invention also relates to a gun cartridge that
comprises a casing in which a percussion primer and a secondary
explosive composition are disposed. The percussion primer is as
described above. The gun cartridge may be a centerfire gun
cartridge or a rimfire gun cartridge.
[0014] The present invention also relates to primer-containing
ordnance assemblies comprising a housing in which a percussion
primer and a secondary explosive composition are disposed. The
percussion primer is as described above. The primer-containing
ordnance assembly may be (without limitation) a grenade, mortar,
detcord initiator, mortar round, rocket motor, or other system
including a percussion primer and secondary explosive composition,
alone or in combination with a propellant.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0015] While the specification concludes with claims particularly
pointing out and distinctly claiming that which is regarded as the
present invention, the advantages of this invention may be more
readily ascertained from the following description of the invention
when read in conjunction with the accompanying drawings in
which:
[0016] FIG. 1 is a scanning electron micrograph of crystals of
CL-20 sensitized with aluminum;
[0017] FIGS. 2A and 2B are cross-sectional views of a rimfire gun
cartridge;
[0018] FIGS. 3A and 3B are cross-sectional views of a centerfire
gun cartridge;
[0019] FIG. 4 is a schematic illustration of exemplary ordnance in
which a percussion primer of the present invention is used; and
[0020] FIGS. 5 and 6 show the results of Allegheny Ballistics
Laboratory ("ABL") impact testing conducted on sensitized
explosives.
DETAILED DESCRIPTION OF THE INVENTION
[0021] An explosive composition for use as a percussion primer is
disclosed. As used herein, the term "percussion primer" refers to
an explosive composition that detonates under slight percussion.
For instance, the percussion primer may be initiated by heat, shock
waves, or a combination of heat and shock waves. Upon ignition, the
percussion primer may generate heat, but little gas, and condensing
hot particles that are of sufficient energy to ignite a secondary
explosive composition or charge. The percussion primer of the
present invention utilizes ingredients that are low in toxicity,
free of heavy metals, stable to aging, nonhygroscopic, and
noncorrosive. When combusted, the percussion primer may produce
nontoxic, nonhygroscopic, and noncorrosive combustion products. The
percussion primer may also be highly reliable in that the
percussion primer reliably ignites the secondary explosive
composition over ambient temperature extremes.
[0022] The percussion primer includes a sensitized explosive, an
oxidizer, and a melt binder. The sensitized explosive may include
an explosive and a sensitizer. As used herein, the term "sensitized
explosive" refers to an explosive that is rendered more sensitive
to impact and friction by association with the sensitizer than the
explosive alone (the unsensitized explosive). The sensitized
explosive of the present invention may provide substantially the
same impact sensitivity to the percussion primer as lead styphnate
provides to a conventional percussion primer. The explosive may be
a solid material that is moderately insensitive to impact and that
decomposes upon melting. For instance, the explosive may have an
impact sensitivity that ranges from approximately 0.3 kp m to
approximately 0.75 kp m. Examples of explosives suitable for use in
the percussion primer of the present invention include, but are not
limited to, CL-20, PETN, RDX, HMX, or mixtures thereof. The
explosive may have a particle size that ranges from approximately
0.1 .mu.m to approximately 100 .mu.m, with an average particle size
that ranges from approximately 20 .mu.m to approximately 5.0 .mu.m.
The explosive may have a bimodal or trimodal particle size
distribution. However, the explosive used in the percussion primer
is not limited to a particular particle size or particle size range
because the explosive is dissolved in a solvent as the sensitized
explosive is prepared. An explosive that is highly sensitive to
impact may be undesirable for use in the percussion primer because
the explosive may unexpectedly initiate, such as without an impact
event. However, an explosive that is not sufficiently impact
sensitive may also be undesirable because the explosive may not
initiate upon impact, even if sensitized by the sensitizer.
[0023] Since the explosive used in the percussion primer is
moderately insensitive, the sensitizer may be used to increase the
sensitivity of the explosive. The explosive may be sensitized to
impact by precipitating the explosive onto the sensitizer, as
described below. The sensitizer may be a solid material that is
thermally stable and does not oxidize. For instance, the sensitizer
may be an electron rich compound or a reducing agent. Examples of
materials that may be used as the sensitizer include, but are not
limited to, aluminum, aluminum oxide, titanium, zirconium,
magnesium, boron, silicon, melamine, styrene, lithium aluminum
hydride, calcium silicide, or mixtures thereof. The sensitizer may
be selected based on the sensitivity of the explosive and the
intended use of the percussion primer. The sensitizer may have a
bimodal particle size distribution and have a particle size that
ranges from approximately 0.1 .mu.m (approximately 100 nm) to
approximately 100 .mu.m.
[0024] If the sensitizer is aluminum, the aluminum may have an
average particle size that ranges from approximately 0.1 .mu.m to
approximately 5 .mu.m. For the sake of example only, Alex.RTM.,
which is a nanoaluminum powder having a particle size that ranges
from approximately 100 nm to approximately 600 nm and having an
average particle size of approximately 210 nm, may be used.
Alex.RTM. is available from Argonide Corp. (Sanford, Fla.). The
H-series (H-2, H-3, or H-5) of powdered aluminum, which is
available from Valimet, Inc. (Stockton, Calif.), may also be used
in the percussion primer. The powdered H-2 aluminum has an average
particle size of approximately 2 .mu.m, the powdered H-3 has an
average particle size of approximately 3 .mu.m, and the powdered
H-5 has an average particle size of approximately 5 .mu.m.
Nanosized aluminum may also be used and is available from Nanotech
(Austin, Tex.). The particle size of the aluminum used in the
percussion primer may be selected based on the intended purpose of
the percussion primer. For instance, if the percussion primer is to
be used in small arms ammunition, aluminum having a small particle
size, such as Alex.RTM., may be used. If larger particle size
aluminum is used in the small arms ammunition, the percussion
primer may be too brisant for its intended purpose. However, to
dilute or reduce the brisance, an inert filler may optionally be
present in the percussion primer. The inert filler enables a
percussion primer that may otherwise be too brisant to be used in
small arms ammunition. Aluminum having the larger particle size, up
to approximately 5 .mu.m, may be used without dilution in other
applications, such as in larger ordnance. If the sensitizer is
melamine, the melamine may have a particle size that ranges from
approximately 2 .mu.m to approximately 100 .mu.m, with an average
particle size of approximately 12 .mu.m. Melamine is commercially
available from numerous sources, such as from Sigma-Aldrich Co.
(St. Louis, Mo.).
[0025] The explosive may account for from approximately 70% by
weight ("wt %") to approximately 99.5 wt % of a total weight of the
sensitized explosive. The sensitizer may constitute from
approximately 0.5 wt % to approximately 30 wt % of the total weight
of the sensitized explosive. In one embodiment, the sensitized
explosive includes approximately 85 wt % CL-20 and approximately 15
wt % aluminum or approximately 15 wt % melamine. In another
embodiment, the sensitized explosive includes approximately 77.5 wt
% CL-20 and approximately 22.5 wt % aluminum. In another
embodiment, the sensitized explosive includes approximately 70 wt %
CL-20 and approximately 30 wt % aluminum or approximately 30 wt %
melamine. In another embodiment, the sensitized explosive includes
approximately 70 wt % RDX and approximately 30 wt % aluminum. In
another embodiment, the sensitized explosive includes approximately
70 wt % PETN and approximately 30 wt % aluminum or approximately 30
wt % melamine.
[0026] The sensitized explosive may be formed by precipitating the
explosive onto the sensitizer. For instance, the explosive may be
dissolved into a solvent, into which the sensitizer is also added.
The solvent may be any volatile solvent in which the explosive is
soluble. The solvent may be a polar, organic solvent including, but
not limited to, ethyl acetate, acetone, or mixtures thereof. When
the sensitized explosive is to be used in the percussion primer,
the solvent may be evaporated, such as by using heat, reduced
pressure, or combinations thereof. As the solvent evaporates, the
explosive may precipitate onto the sensitizer, producing crystals
of the sensitized explosive. The crystals may be of a sufficiently
small size for the sensitized explosive to be loaded into the
desired ordnance without damaging the crystals. The crystals of the
sensitized explosive may have an average particle size that ranges
from approximately 1 .mu.m to approximately 100 .mu.m. Crystals of
CL-20 sensitized with aluminum are shown in FIG. 1. The CL-20 in
the crystals precipitated as the epsilon-polymorph
(".epsilon.-polymorph"), the most stable form of CL-20, as
determined by Fourier Transform Infrared Spectroscopy (data not
shown).
[0027] Alternatively, the explosive may be dissolved into the
solvent and the sensitizer may be added to a nonsolvent, forming a
slurry of the sensitizer in the nonsolvent. The nonsolvent may be
any nonpolar organic solvent in which the sensitizer is not
soluble, such as hexane, heptane, octane, or mixtures thereof. The
solution of the explosive may be combined with the slurry of the
sensitizer. When the sensitized explosive is to be formulated into
the percussion primer, the solvent and the nonsolvent may be
removed, such as by using heat, reduced pressure, or combinations
thereof, to precipitate the explosive onto the sensitizer. However,
until the sensitized explosive is to be used in the percussion
primer, the sensitized explosive may remain in the solvent or the
solvent and the nonsolvent. Without being bound to a particular
theory, it is believed that precipitating the explosive onto the
sensitizer brings the explosive and sensitizer into intimate
contact, which reduces the activation energy of the explosive. As
such, the sensitized explosive may be more sensitive to impact than
the explosive alone (the unsensitized explosive) and may utilize
less energy to initiate than is needed to initiate the unsensitized
explosive.
[0028] While the sensitivity of the sensitized explosive is
increased, the sensitized explosive may remain safe to handle.
Since the solvent or solvent and nonsolvent are not removed until
the sensitized explosive is ready to be formulated into the
percussion primer, the sensitized explosive is stored in a
substantially wet state and not a substantially dry state. As used
herein, the term "dry" refers to a state of the sensitized
explosive that is free of solvent or solvent and nonsolvent. In
contrast, a "wet" state refers to a state in which the sensitized
explosive is present in the solvent or in the solvent and
nonsolvent. Since the sensitized explosive remains wetted by the
solvent or solvent and nonsolvent, particles of the sensitized
explosive may have insufficient surface area to burn. As such, the
wet, sensitized explosive may only be capable of a surface burn.
When the sensitized explosive is to be used in the percussion
primer, a desired amount of the wet, sensitized explosive may be
dried, such as by removing the solvent or solvent and nonsolvent.
Since large or bulk quantities of the wet, sensitized explosive are
not dried, the sensitized explosive may be safe to handle in the
amounts that are needed in the percussion primer.
[0029] Depending on the intended purpose of the percussion primer
and the desired properties of the percussion primer, the oxidizer
may be a bismuth compound or a conventional oxidizer. While the
bismuth compound may be considered a less effective or weaker,
oxidizer than the conventional oxidizer, the bismuth compound, in
combination with the sensitized explosive, may provide the desired
properties to the percussion primer. In other words, the increased
sensitivity of the sensitized explosive may be balanced by the
reduced oxidizing effect of the bismuth compound. Examples of
bismuth compounds suitable for use in the percussion primer
include, but are not limited to, bismuth oxide ("Bi.sub.2O.sub.3"),
bismuth subnitrate ("BiONO.sub.3"), bismuth tetroxide
("Bi.sub.2O.sub.4"), or mixtures thereof. These bismuth compounds
are nontoxic, noncorrosive, and nonhygroscopic. Therefore, the
bismuth compound may be used as the oxidizer when the resulting
percussion primer is to be noncorrosive or nonhygroscopic. For
instance, the bismuth compound may be used as the oxidizer when the
percussion primer is to be used in a gun cartridge, such as in
centerfire ammunition or in rimfire ammunition. Since the bismuth
compound is noncorrosive, combustion products of the percussion
primer may not corrode the gun barrel. In addition, the bismuth
compound may decompose upon combustion to form metallic bismuth,
which may provide lubrication in the gun barrel, similar to the
effect produced by lead oxide in metallic lead percussion primers.
Bismuth sulfide, or mixtures of bismuth sulfide and at least one of
the previously discussed bismuth compounds, may be used as the
bismuth compound in situations where corrosiveness is not a
concern, such as in grenades.
[0030] If hygroscopicity or corrosiveness of the percussion primer
is not a concern, the conventional oxidizer may be used, such as a
salt or metal salt of a nitrate, chlorate, or perchlorate. For the
sake of example only, the conventional oxidizer may be barium
nitrate, cesium nitrate, potassium nitrate, ammonium nitrate,
potassium chlorate, potassium perchlorate, ammonium perchlorate, or
mixtures thereof. The conventional oxidizer may also be a metal
oxide, metal hydroxide, metal peroxide, metal oxide hydrate, metal
oxide hydroxide, metal hydrous oxide, basic metal carbonate, basic
metal nitrate, or mixtures thereof. For instance, the conventional
oxidizer may be CuO, Co.sub.2O.sub.3, Co.sub.3O.sub.4,
CoFe.sub.2O.sub.4, Fe.sub.2O.sub.3, MoO.sub.3, Bi.sub.2MoO.sub.6,
or mixtures thereof.
[0031] The sensitized explosive may be present in the percussion
primer at from approximately 35 wt % to approximately 55 wt %. When
the percussion primer is to be used in a bullet or other gun
cartridge, the explosive may constitute from approximately 25 wt %
to approximately 40 wt % of a total weight of the percussion
primer. The oxidizer may account for from approximately 20 wt % to
approximately 75 wt % of the percussion primer.
[0032] The melt binder may be a nonhygroscopic material having a
melting point of less than or equal to approximately 120.degree.
C., such as a melting point that ranges from approximately
80.degree. C. to approximately 120.degree. C. The melt binder may
be a hydrophobic material that has a low viscosity when melted.
Examples of melt binders that may be used include, but are not
limited to, a wax having a melting point above ambient temperature
(approximately 25.degree. C.), trinitrotoluene ("TNT"),
poly(3,3-bis(azidomethyl)oxetane) ("poly(BAMO)"),
poly(3-azidomethyl-3-methyloxetane) ("poly(AMMO)"),
ethyl-3,5-dinitrobenzoate, 1,3,3-trinitroazetine ("TNAZ"), natural
gums, or mixtures thereof. The wax may be bees wax, paraffin wax,
microcrystalline wax, synthetic waxes, carnauba wax, ozokerite wax,
a polyethylene wax, a hydrocarbon wax, or mixtures thereof. Since
the melt binder has a low viscosity when melted, the melt binder
may flow around the crystals of the sensitized explosive, coating
the crystals. The melt binder may also have a strong affinity for
the ingredients in the percussion primer and for metal surfaces in
which the percussion primer is housed, such as the metal surfaces
of ordnance, such as in bullets, grenades, etc. Accordingly, the
melt binder may be used to bind together the percussion primer and
hold the percussion primer in place in the ordnance. A small amount
of the melt binder may be present in the percussion primer. For
instance, in centerfire ammunition, the melt binder may be present
in the percussion primer at from approximately 0.5 wt % to less
than approximately 10 wt %, such as at approximately 1.5 wt %. In
rimfire ammunition, the melt binder may be present in the
percussion primer at from approximately 0.5 wt % to less than
approximately 10 wt %, such as approximately 3 wt %.
[0033] The percussion primer may also include optional ingredients,
such as an inert filler, diluent, binder, low output explosive, or
mixtures thereof. The optional ingredient may be glass,
nitrocellulose ("NC"), tetracene, or mixtures thereof. Glass may be
used in the percussion primer as an inert filler or diluent that
reduces the energy or brisance of the percussion primer. For
instance, if a potential formulation of a percussion primer is too
energetic to be effectively used to ignite the secondary explosive
composition, glass, NC, or mixtures thereof may be added to the
percussion primer to reduce its brisance. Bi.sub.2O.sub.3 may also
be used to reduce the brisance of the percussion primer. If glass
is present in the percussion primer, the glass may be ground to a
mesh size that ranges from approximately #80 mesh to approximately
#120 mesh. The NC used in the percussion primer may be in a fibrous
form. In addition to functioning as an inert filler, the NC may
function as a binder or reinforcing agent, providing strength to a
pellet formed from the percussion primer. Tetracene, which is a
sensitive, but low output, explosive, may also be used in the
percussion primer. The tetracene may improve reliability of the
percussion primer (i.e., reduce the percussion primer failure
rate). While these optional ingredients, if present, provide
desirable properties to the percussion primer, the percussion
primer may be formulated for its intended purpose without using
these ingredients.
[0034] The percussion primer may be produced by measuring desired
amounts of the sensitized explosive and the other ingredients, such
as the oxidizer, the melt binder, and any optional ingredients. The
other ingredients may be combined with the sensitized explosive,
such as in a mixer, to produce the percussion primer composition.
Since the sensitized explosive is stored wet, the sensitized
explosive may be dried, as previously described, before combining
the sensitized explosive with the other ingredients. To achieve a
desired consistency of the percussion primer, the ingredients of
the percussion primer may be wetted with water or a volatile,
nonpolar organic solvent. The organic solvent used to wet the
ingredients of the percussion primer may be hexane, heptane,
octane, or mixtures thereof. Alternatively, the wet, sensitized
explosive may be combined with the other ingredients of the
percussion primer, i.e., without first removing the solvent or the
solvent and nonsolvent. The resulting percussion primer is not
sticky and, therefore, may be easily removed from equipment used to
process the percussion primer. Since little material remains on the
processing equipment, high yields of the percussion primer may be
achieved. In addition, the percussion primer may be easily loaded
into gun cartridges or other ordnance. The percussion primer may be
formed into a desired shape, such as a pellet, which is selected
based on the intended purpose of the percussion primer. Possible
shapes of the percussion primer, and methods of fabricating these
shapes, are known in the art and, therefore, are not described in
detail herein. Any solvents or water may subsequently be removed,
producing the percussion primer. However, if water is used to
process a percussion primer that includes aluminum, the water may
be removed before exposing the percussion primer to elevated
temperatures, preventing the aluminum from reacting with the
water.
[0035] Properties of the percussion primer may depend on relative
amounts of each of the ingredients that are present. For instance,
combustion properties of the percussion primer may be tailored by
varying the relative amounts of the explosive, the sensitizer, the
oxidizer, the melt binder, and any optional ingredients to achieve
properties that are optimal for the intended purpose of the
percussion primer. Since the properties of the percussion primer
are tailorable, the percussion primer may be used in a wide variety
of ordnance to initiate the secondary explosive composition.
Examples of ordnance in which the percussion primer may be used
include, but are not limited to, small arms ammunition, grenades,
mortars, or detcord initiators. The percussion primer may also be
used to initiate or prime mortar rounds, rocket motors,
illuminating flares, or signaling flares. For the sake of example
only, the percussion primer may be used in a gun cartridge, such as
in a centerfire gun cartridge or in a rimfire gun cartridge. The
secondary explosive composition that is used in the ordnance may be
selected by one of ordinary skill in the art and, therefore, is not
discussed in detail herein. For instance, if the ordnance is a gun
cartridge, the secondary explosive composition may be a smokeless
gunpowder. In a grenade, the percussion primer may ignite a delay
charge. In many cases, such as in mortar rounds or medium artillery
cartridges, the percussion primer may ignite a booster charge that
includes black powder or boron/potassium nitrate with an organic
binder.
[0036] In one embodiment, the percussion primer is used in a
centerfire gun cartridge or m a rimfire gun cartridge. Rimfire
ignition differs significantly from centerfire ignition and,
therefore, a percussion primer that is suitable for use in the
centerfire gun cartridge may not provide optimal performance in the
rimfire gun cartridge. In small arms using the rimfire gun
cartridge, a firing pin strikes a rim of a casing of the gun
cartridge. In contrast, the firing pin of small arms using the
centerfire gun cartridge strikes a metal cup in the center of the
cartridge casing containing the percussion primer. Gun cartridges
and cartridge casings are known in the art and, therefore, are not
discussed in detail herein. The force or impact of 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. As shown in FIGS. 2A and 2B, the percussion primer 2 may be
substantially evenly distributed around an interior volume defined
by a rim portion 3 of a casing 4 of the rimfire gun cartridge 6.
FIG. 2B is an enlarged view of an anterior portion of the rimfire
gun cartridge 6. In the centerfire gun cartridge 8, the percussion
primer 2 may be positioned in an aperture 10 in the casing 4, as
shown in FIGS. 3A and 3B. FIG. 3B is an enlarged view of a
component of the centerfire gun cartridge 8. The secondary
explosive 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. When ignited or combusted, the
percussion primer 2 may produce sufficient heat and condensing hot
particles to ignite the secondary explosive 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, 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.
[0037] As previously mentioned, 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. In the ordnance,
motor or system 14, the percussion primer 2 may be positioned
substantially adjacent to the secondary explosive composition 12 in
a housing 16, as shown in FIG. 4. Of course, in the instance of a
system including a propellant (not shown) the secondary explosive
composition 12 would typically be used to initiate the
propellant.
[0038] The following examples serve to explain embodiments of the
present invention in more detail. These examples are not to be
construed as being exhaustive or exclusive as to the scope of this
invention.
EXAMPLES
Example 1
Sensitized CL-20: 77.5% CL-20 and 22.5% Aluminum (Alex.RTM.)
[0039] CL-20 (50 g) was dissolved in 150 ml of ethyl acetate. The
solution was poured into a 400 ml beaker having a magnetic stirring
bar and was stirred on a warm hot plate. Alex.RTM. aluminum (14.5
g) was poured into the solution, forming a slurry. An air tube was
positioned in the beaker to increase the evaporation rate of the
ethyl acetate. The ethyl acetate was evaporated until the magnetic
stirring bar nearly stuck in the thick slurry that formed upon
evaporation of the ethyl acetate. Heptane (50 ml) was added to the
beaker and evaporated. An additional amount of heptane (50 ml) was
added to the beaker and the beaker removed from the hot plate.
After removing the magnetic stirring bar, the sensitized CL-20 was
dried by removing the heptane. The dried, sensitized CL-20 was used
for testing or was formulated into a percussion primer.
Example 2
Sensitized CL-20: 85% CL-20 and 15% Aluminum (Alex).RTM.
[0040] A 250-ml round bottom flask having a magnetic stirring bar
was charged with 50 g ethyl acetate. CL-20 (8.5 g) was dissolved in
the ethyl acetate. Alex.RTM. aluminum (1.5 g) was added to the
solution, followed by 150 g of heptane. The ethyl acetate and
heptane were slowly removed under vacuum at 40.degree. C. using a
rotary evaporator. The dried, sensitized CL-20 was used for testing
or was formulated into a percussion primer.
Example 3
Sensitized CL-20: 70% CL-20 and 30% Aluminum (Alex.RTM.)
[0041] A 250-ml round bottom flask having a magnetic stirring bar
was charged with 50 g ethyl acetate. CL-20 (7.08 g) was dissolved
in the ethyl acetate. Alex.RTM. aluminum (3.08 g) was added to the
solution, followed by 150 g of heptane. The ethyl acetate and
heptane were slowly removed under vacuum at 40.degree. C. using a
rotary evaporator. The dried, sensitized CL-20 was used for testing
or was formulated into a percussion primer.
Example 4
Sensitized CL-20: 70% CL-20 and 30% Aluminum (H-5)
[0042] A 250-ml round bottom flask having a magnetic stirring bar
was charged with 50 g ethyl acetate. CL-20 (1.4 g) was dissolved in
the ethyl acetate. Valimet H-5 spherical aluminum (0.6 g) was
slowly added to the solution, followed by 160 g of heptane. The
ethyl acetate and heptane were slowly removed under vacuum at
40.degree. C. using a rotary evaporator. The dried, sensitized
CL-20 was used for testing or was formulated into a percussion
primer.
Example 5
Sensitized CL-20: 70% CL-20 and 30% Aluminum (H-2)
[0043] A 250-ml round bottom flask having a magnetic stirring bar
was charged with 50 g ethyl acetate. CL-20 (1.4 g) was dissolved in
the ethyl acetate. Valimet H-2 aluminum (0.6 g) was added to the
solution, followed by 160 g of heptane. The ethyl acetate and
heptane were slowly removed under vacuum at 40.degree. C. using a
rotary evaporator. The dried, sensitized CL-20 was used for testing
or was formulated into a percussion primer.
Example 6
Sensitized CL-20: 85% CL-20 and 15% Melamine
[0044] A 250-ml round bottom flask having a magnetic stirring bar
was charged with 50 g ethyl acetate. CL-20 (8.5 g) was dissolved in
the ethyl acetate. Melamine (1.5 g) was added to the solution,
followed by 150 g of heptane. The melamine had an average particle
size of approximately 10 .mu.m. The ethyl acetate and heptane were
slowly removed under vacuum at 40.degree. C. using a rotary
evaporator. The dried, sensitized CL-20 was used for testing or was
formulated into a percussion primer.
Example 7
Sensitized CL-20: 70% CL-20 and 30% Melamine
[0045] A 250-ml round bottom flask having a magnetic stirring bar
was charged with 50 g ethyl acetate. CL-20 (7.08 g) was dissolved
in the ethyl acetate. Melamine (3.08 g) was added to the solution,
followed by 150 g of heptane. The melamine had an average particle
size of approximately 10 .mu.m. The ethyl acetate and heptane were
slowly removed under vacuum at 40.degree. C. using a rotary
evaporator. The dried, sensitized CL-20 was used for testing or was
formulated into a percussion primer.
Example 8
Sensitized RDX: 70% RDX and 30% Aluminum (Alex.RTM.)
[0046] A 250-ml round bottom flask having a magnetic stirring bar
was charged with 50 g acetone. RDX (7.08 g) was dissolved in the
acetone. Alex.RTM. aluminum (3.08 g) was added to the solution,
followed by 150 g of heptane. The acetone and heptane were slowly
removed under vacuum at 40.degree. C. using a rotary evaporator.
The dried, sensitized RDX was used for testing or was formulated
into a percussion primer.
Example 9
Sensitized RDX: 70% RDX and 30% Aluminum (H-2)
[0047] A 250-ml round bottom flask having a magnetic stirring bar
was charged with 50 g acetone. RDX (1.4 g) was dissolved in the
acetone. Valimet H-2 aluminum (0.6 g) was added to the solution,
followed by 150 g of heptane. The acetone and heptane were slowly
removed under vacuum at 40.degree. C. using a rotary evaporator.
The dried, sensitized RDX was used for testing or was formulated
into a percussion primer.
Example 10
Sensitized PETN: 70% PETN and 30% Melamine
[0048] A 250-ml round bottom flask having a magnetic stirring bar
was charged with 20 g ethyl acetate. PETN (1.4 g) was dissolved in
the ethyl acetate. Melamine (0.6 g) was added to the solution,
followed by 60 g of heptane. The melamine had an average particle
size of approximately 10 .mu.m. The ethyl acetate and heptane were
slowly removed under vacuum at 40.degree. C. using a rotary
evaporator. The dried, sensitized PETN was used for testing or was
formulated into a percussion primer.
Example 11
Sensitized PETN: 70% PETN and 30% Aluminum (Alex.RTM.)
[0049] A 250-ml round bottom flask having a magnetic stirring bar
was charged with 60 g ethyl acetate. PETN (1.4 g) was dissolved in
the ethyl acetate. Alex.RTM. aluminum (0.6 g) was added to the
solution, followed by 100 g of heptane. The ethyl acetate and
heptane were slowly removed under vacuum at 40.degree. C. using a
rotary evaporator. The dried, sensitized PETN was used for testing
or was formulated into a percussion primer.
Example 12
Impact Sensitivity of Sensitized CL-20
[0050] The impact sensitivity of sensitized CL-20 was measured
using an impact test developed by Allegheny Ballistics Laboratory
("ABL") as known in the art. The impact sensitivity of the
sensitized CL-20 was compared to that of unsensitized CL-20 and to
a K75 primer. The CL-20 was sensitized with aluminum or with
melamine, which was prepared as described in Examples 2, 3, and 6.
One formulation of sensitized CL-20 included 70% CL-20 and 30%
Alex.RTM., a second formulation of sensitized CL-20 included 85%
CL-20 and 15% Alex.RTM., and a third formulation of sensitized
CL-20 included 85% CL-20 and 15% melamine. The K75 primer included
39% lead styphnate, 10.8% antimony sulfide, 41% barium nitrate,
2.5% tetracene, 6.3% propellant fines (24:76
nitroglycerin:nitrocellulose), 0.2% gum arabic, and 0.2% gum
tragacanth (federal internal specifications allow the ingredients
of the K75 primer to vary by +/-3%).
[0051] The ABL impact was determined by dropping a 0.5 kg weight
from a given height onto a mass (15 mg to 30 mg) of the sensitized
CL-20. If the impact between the weight and the sensitized CL-20
caused the sensitized CL-20 to detonate (indicated by the
production of smoke, sparks, or ignition), this event was reported
as a "GO." The probability of a "GO" as a function of the drop
height is shown in FIG. 5 for each of the tested formulations. This
data was inputted into a numerical fitting program, yielding the
"calculated" plots. The CL-20 sensitized with the aluminum and the
CL-20 sensitized with the melamine had comparable impact
sensitivity compared to the K75 primer. The CL-20 sensitized with
the aluminum and the CL-20 sensitized with the melamine also had
comparable or increased impact sensitivity compared to the
unsensitized CL-20.
[0052] FIG. 6. shows the effect on ABL impact sensitivity of CL-20
sensitized with different types of nanoparticle sized aluminum and
with melamine. FIG. 6 also shows the effect of varying the
concentration of the sensitizer used in the percussion primer. The
CL-20 was sensitized with Nanotech aluminum (available from
Nanotech (Austin, Tex.)) and with Alex.RTM.. Varying concentrations
of the aluminum sensitizers (5 wt %, 15 wt %, and 25 wt % of the
sensitized explosive) were tested. The CL-20 was also sensitized
with melamine, which was tested in the sensitized explosive at
concentrations of 5 wt % and 15 wt %. The impact sensitivity of the
sensitized CL-20 was compared to that of unsensitized CL-20 and to
that of basic lead styphnate, which is labeled in FIG. 6 as
(PbOH).sub.2TNR. The sensitized CL-20 showed increased impact
sensitivity compared to the unsensitized CL-20. The sensitized
CL-20 also showed comparable or slightly decreased impact
sensitivity compared to that of the basic lead styphnate.
Example 13
Formulations of Percussion Primers Used in Centerfire
Ammunition
[0053] Percussion primers having the formulations shown in Table 1
were produced by sensitizing the CL-20 or PETN with Alex.RTM.
aluminum. The sensitized explosives were prepared as described in
Examples 3 and 11. To form each of the percussion primers, the
sensitized CL-20 or the sensitized PETN were combined with the
remaining ingredients indicated in Table 1. TABLE-US-00001 TABLE 1
Formulations of Sensitized CL-20 and Sensitized PETN Percussion
Primers. Formu- Formu- Formu- Formu- Formu- lation lation lation
lation lation 1 2 3 4 5 Ingredient (wt %) (wt %) (wt %) (wt %) (wt
%) 70% CL-20 38.4 38.3 -- 42 39 sensitized with 30% Alex .RTM.
Aluminum 70% PETN -- -- 46 -- -- sensitized with 30% Alex .RTM.
Aluminum Bi.sub.2O.sub.3 46.5 46.4 38.5 52 46 Ground Glass, 9.2 8.7
9 -- 13 #80 mesh size Fibrous 4.6 4.7 4.8 4.2 -- Nitrocellulose
Ethyl-3,5- 1.5 1.7 1.7 -- -- dinitrobenzoate Poly(BAMO) -- -- --
1.8 1.6
[0054] Each of Formulations 1-5 was loaded into a centerfire
ammunition. The centerfire ammunition was shot to determine the
effectiveness of each of the formulations as a percussion primer.
Each of the formulations was effective as a percussion primer. As
shown by Formulation 4, which lacks ground glass, ground glass is
not needed in the percussion primer to achieve effective combustion
properties. Nitrocellulose is also not needed in the percussion
primer for effective combustion properties, as shown by Formulation
5, which lacks nitrocellulose.
Example 14
Formulation of a Percussion Primer Used in Rimfire Ammunition
[0055] A percussion primer having the formulation shown in Table 2
was produced by sensitizing the CL-20 with Alex.RTM. aluminum, as
described in Example 3. To form the percussion primer, the
sensitized CL-20 was combined with the remaining ingredients
indicated in Table 2. TABLE-US-00002 TABLE 2 Formulations of
Sensitized CL-20 Percussion Primers. Formulation Ingredient 1 (wt
%) 70% CL-20 sensitized with 30% Alex .RTM. Aluminum 50
Bi.sub.2O.sub.3 21 Ground Glass, #120 mesh size 22 Tetracene 4
Ethyl-3,5-dinitrobenzoate 3
[0056] Formulation 1 was loaded into a rimfire gun cartridge. The
rimfire gun cartridge was shot to determine the effectiveness of
the formulation as a percussion primer. The formulation was
effective as a percussion primer.
[0057] While the invention may be susceptible to various
modifications and alternative forms, specific embodiments have been
shown by way of example in the drawings and have been described in
detail herein. However, it should be understood that the invention
is not intended to be limited to the particular forms disclosed.
Rather, the invention is to cover all modifications, equivalents,
and alternatives falling within the spirit and scope of the
invention as defined by the following appended claims.
* * * * *