U.S. patent application number 10/646965 was filed with the patent office on 2004-07-08 for reduced sensitivity melt-cast explosives.
Invention is credited to Doll, Daniel W., Hanks, Jami M., Highsmith, Thomas K., Lund, Gary K..
Application Number | 20040129356 10/646965 |
Document ID | / |
Family ID | 22623921 |
Filed Date | 2004-07-08 |
United States Patent
Application |
20040129356 |
Kind Code |
A1 |
Doll, Daniel W. ; et
al. |
July 8, 2004 |
REDUCED SENSITIVITY MELT-CAST EXPLOSIVES
Abstract
A melt-cast explosive which shares comparable explosive
properties to those of COMP B explosives and is melt-pourable and
castable under conditions comparable to those of COMP B explosives,
but experiences less impact, shock, and thermal sensitivity and
avoids the issues of toxicity associated with COMP B. A fundamental
and well-accepted component of COMP B, i.e., trinitrotoluene (TNT),
is replaced with one or more mononitro-substituted or
dinitro-substituted melt-cast binders, such as dinitroanisole,
which can be melt-cast without presenting the toxicity drawbacks
experienced with the use of TNT. The melt-cast binder can also be
combined with a processing aid selected from the group consisting
of alkylnitroanilines and arylnitroanilines. Preferably, the
composition also includes coarse oxidizer particles and energetic
filler in fine particulate form.
Inventors: |
Doll, Daniel W.; (Ogden,
UT) ; Hanks, Jami M.; (Logan, UT) ; Highsmith,
Thomas K.; (North Ogden, UT) ; Lund, Gary K.;
(Malad, IN) |
Correspondence
Address: |
TRASK BRITT
P.O. BOX 2550
SALT LAKE CITY
UT
84110
US
|
Family ID: |
22623921 |
Appl. No.: |
10/646965 |
Filed: |
August 22, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10646965 |
Aug 22, 2003 |
|
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09747303 |
Dec 21, 2000 |
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6648998 |
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60171490 |
Dec 22, 1999 |
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Current U.S.
Class: |
149/92 |
Current CPC
Class: |
C06B 21/005 20130101;
C06B 25/06 20130101 |
Class at
Publication: |
149/092 |
International
Class: |
C06B 025/34 |
Goverment Interests
[0002] The U.S. Government has a paid-up license in this invention
and the right in limited circumstances to require the patent owner
to license others on reasonable terms as provided by the terms of
DAAE30-97-C-1040 to Picatinny Arsenal.
Claims
What is claimed is:
1. A melt-cast explosive composition comprising: at least one
binder comprising at least one member selected from the group
consisting of mononitro-substituted arenes and dinitro-substituted
arenes; at least one processing aid comprising at least one member
selected from the group consisting of N-alkylnitroanilines and
N-arylnitroanilines, the at least one processing aid and the at
least one binder forming a mixture having a melting temperature in
a range of from about 80.degree. C. to about 110.degree. C.;
oxidizer particles having particle diameters in a range of from
about 20 .mu.m to about 600 .mu.m; and at least one energetic
filler having particles sizes in a range of from about 2 .mu.m to
about 10 .mu.m, wherein the melt-cast explosive composition is
melt-pourable at at least one temperature in the range of from
about 80.degree. C. to about 110.degree. C.
2. The melt-cast explosive composition of claim 1, wherein the at
least one binder comprises at least one member selected from the
group consisting of nitrotoluenes, dinitrotoluenes, and
dinitronaphthalenes.
3. The melt-cast explosive composition of claim 1, wherein the at
least one binder is further substituted and comprises at least one
member selected from the group consisting of nitrophenols,
dinitrophenols, mononitroanilines, and dinitroanilines.
4. The melt-cast explosive composition of claim 1, wherein the at
least one energetic filler comprises at least one member selected
from the group consisting of
1,3,5-trinitro-1,3,5-triaza-cyclohexane (RDX),
1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX),
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 (HNIW),
4,10-dinitro-2,6,8,12-tetraoxa-4,10-diazatetracy-
clo[5.5.0.0.sup.5,90.sup.3,11]dodecane (TEX), nitroguanidine (NQ),
1,3,5-triamino-2,4,6-trinitrobenzene (TATB),
1,1-diamino-2,2-dinitroethan- e (DADNE), 1,3,3-trinitroazetidine
(TNAZ), and 3-nitro-1,2,4-triazol-5-one (NTO).
5. The melt-cast explosive composition of claim 1, wherein the
oxidizer particles comprise at least one member selected from the
group consisting of inorganic perchlorates and inorganic
nitrates.
6. The melt-cast explosive composition of claim 5, wherein the at
least one energetic filler comprises
1,3,5-trinitro-1,3,5-triazacyclohexane (RDX).
7. The melt-cast explosive composition of claim 6, wherein the at
least one processing aid comprises at least one
N-alkyl-nitroaniline.
8. The melt-cast explosive composition of claim 6, wherein the at
least one processing aid comprises N-methyl-nitroaniline.
9. A melt-cast explosive composition comprising: at least one
binder comprising at least one member selected from the group
consisting of mononitro-substituted arenes and dinitro-substituted
arenes, the at least one binder being free of --NH.sub.2
functionalities; at least one processing aid comprising at least
one member selected from the group consisting of
N-alkylnitroanilines and N-arylnitroanilines, the at least one
processing aid is different than the at least one binder and
combines with the at least one binder to form a mixture having a
melting temperature in a range of from about 80.degree. C. to about
110.degree. C.; oxidizer particles having particle diameters in a
range of from about 20 .mu.m to about 600 .mu.m; and at least one
energetic filler having particle sizes in a range of from about 2
.mu.m to about 10 .mu.m, wherein the melt-cast explosive
composition is melt-pourable at at least one temperature in the
range of from about 80.degree. C. to about 110.degree. C.
10. The melt-cast explosive composition of claim 9, wherein the at
least one processing aid accounts for about 0.15 weight percent to
about 1 weight percent of a total weight of the melt-cast explosive
composition.
11. The melt-cast explosive composition of claim 9, wherein the at
least one binder accounts for 25 weight percent to 45 weight
percent of a total weight of the melt-cast explosive
composition.
12. The melt-cast explosive composition of claim 9, wherein the at
least one binder accounts for 30 weight percent to 40 weight
percent of a total weight of the melt-cast explosive
composition.
13. The melt-cast explosive composition of claim 9, wherein the at
least one binder comprises at least one member selected from the
group consisting of nitrotoluenes, dinitrotoluenes, and
dinitronaphthalenes.
14. The melt-cast explosive composition of claim 9, wherein the at
least one binder is further substituted and comprises at least one
member selected from the group consisting of nitrophenols,
dinitrophenols, mononitroanilines, and dinitroanilines.
15. The melt-cast explosive composition of claim 9, wherein the at
least one energetic filler comprises at least one member selected
from the group consisting of
1,3,5-trinitro-1,3,5-triaza-cyclohexane (RDX),
1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX),
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 (HNIW),
4,10-dinitro-2,6,8,12-tetraoxa-4,10-diazatetracy-
clo[5.5.0.0.sup.5,90.sup.3,11]dodecane (TEX), nitroguanidine (NQ),
1,3,5-triamino-2,4,6-trinitrobenzene (TATB),
1,1-diamino-2,2-dinitroethan- e (DADNE), 1,3,3-trinitroazetidine
(TNAZ), and 3-nitro-1,2,4-triazol-5-one (NTO).
16. The melt-cast explosive composition of claim 9, wherein the
oxidizer particles comprise at least one member selected from the
group consisting of inorganic perchlorates and inorganic
nitrates.
17. The melt-cast explosive composition of claim 16, wherein the at
least one energetic filler comprises
1,3,5-trinitro-1,3,5-triaza-cyclohexane (RDX).
18. The melt-cast explosive composition of claim 17, wherein the at
least one processing aid comprises at least one
N-alkyl-nitroaniline.
19. The melt-cast explosive composition of claim 17, wherein the at
least one processing aid comprises N-methyl-nitroaniline.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of application Ser. No.
09/747,303, filed Dec. 21, 2000, pending, which claimed priority of
U.S. Provisional Application 60/171,490 filed Dec. 22, 1999.
BACKGROUND OF THE INVENTION
[0003] Field of the Invention: This invention relates to melt-cast
explosives, and in particular to melt-cast explosives suitable for
use in mortars, grenades, artillery shells, warheads, and
antipersonnel mines.
[0004] State of the Art: Melt-cast explosives based on a
2,4,6-trinitrotoluene (TNT) melt-cast binder have been used in a
wide array of military applications. Among the TNT-based
compositions known for making melt-cast explosives, COMP B (also
commonly referred to in the art as Composition B comprises a
mixture of TNT, RDX (1,3,5-trinitro-1,3,5-triaza-cyclohexane), and
beeswax. Although the precise concentrations of these ingredients
may vary somewhat in industry practice, generally COMP B includes
about 39.5 wt % TNT, about 59.5 wt % RDX class 1 (100 .mu.m) and
about 1 wt % wax.
[0005] COMP B is typically prepared by initially melting the TNT
melt-cast binder, which has a relatively low melting temperature of
about 81.degree. C. RDX particles and wax (optionally precoated on
the RDX particles) are then stirred into the melted TNT until a
slurry or homogeneous dispersion is obtained. The molten slurry can
be poured into shells or casings for mortars, grenades, artillery,
warheads, mines, and the like by a casting process, then allowed to
cool and solidify. The melt-pourability of COMP B is characteristic
of melt-cast explosives.
[0006] As widely acknowledged in the art, however, melt-cast
explosive compositions such as COMP B have several drawbacks. One
of the most acknowledged of these drawbacks is the tendency of
melt-cast explosives to shrink and crack upon cooling. Separation
of the melt-cast explosive from its shell or casing and the
formation of cracks within the explosive significantly increase the
shock (or impact) sensitivity of the melt-cast explosive. Due to
this increase in shock/impact sensitivity, melt-cast explosives
made of COMP B and the like have been determined to lack sufficient
predictability for some military applications. In particular, such
melt-cast explosives are particularly prone to premature detonation
when used adjacent to an ordnance motor. Moreover, due to the high
thermal sensitivity and toxicity of TNT as a melt-cast binder,
safety precautions are often required in practicing melt-cast
techniques, thereby adding to manufacturing costs, slowing
production rates, and raising worker safety issues. TNT is no
longer produced domestically. The primary reason is because the
manufacture of TNT produces toxic by-products known as pink water.
During the TNT purification process, the meta isomers produced
during the nitration of toluene react with the sodium sulfite to
produce water soluble, sulfated nitro toluene that is red and
highly toxic. The waste stream cleanup is labor intensive, thereby
increasing cost significantly.
BRIEF SUMMARY OF THE INVENTION
[0007] The present invention provides a melt-cast explosive that
shares comparable explosive properties to those of COMP B
explosives and is melt-pourable and castable under conditions
comparable to those of COMP B explosives, but experiences less
impact, shock, and thermal sensitivity and avoids the issues of
toxicity associated with COMP B.
[0008] In accordance with the present invention, a fundamental and
well-accepted component of COMP B, i.e., the trinitrotoluene (TNT)
melt-cast binder is replaced with one or more mononitro-substituted
arenes or dinitro-substituted arenes, such as dinitroanisole. It
has been discovered that mononitro-substituted and
dinitro-substituted arenes such as dinitroanisole can be melt-cast
without presenting the toxicity drawbacks experienced with the use
of TNT. Additionally, many mononitro-substituted and
dinitro-substituted arenes are lower in costs and more widely
available than TNT. Mononitro- and dinitro-arenes are less
detonable than tri-nitrated arenes. Therefore, the mononitro- and
dinitro-arenes do not require the explosive transportation,
storage, and packaging infrastructure that tri-nitrated compounds,
such as TNT, mandate.
[0009] Generally, the use of mononitro-substituted and
dinitro-substituted arenes in place of TNT for melt-cast
compositions has been disfavored (if not overlooked) in the
melt-casting art due to the lower energetic oxygen content of the
mononitro-substituted and dinitro-substituted arenes compared to
TNT. This drawback has been recognized and overcome by the
inventors by the addition of coarse oxidizer particles to the
melt-cast composition. As referred to herein, "coarse" means
particles having a granular appearance. The coarse oxidizer
particles compensate for the energy loss experienced by the
replacement of TNT with the less-energetic mononitro-substituted
and/or dinitro-substituted arene melt-cast binder. Further,
relatively large coarse oxidizer particles reduce the shock,
impact, and thermal sensitivities. Inorganic oxidizers are
preferred.
[0010] Additionally, the different melting points of
mononitro-substituted and dinitro-substituted arenes from that of
TNT have also disfavored the melt-cast binder substitution proposed
by the inventors. Melt-casting requires heating of the melt-cast
binder to a temperature higher than its melting point, so that the
binder can be mixed with the energetic filler and cast by
melt-pouring. A typical and useful melting point range for the melt
or pour process is 80.degree. C. to 110.degree. C. However,
melt-cast compositions should not be heated close to or above their
autoignition temperatures, since the compositions will ignite
automatically and generate an exothermic burn or explosion if
heated to their autoignition temperatures. Preferably, a relatively
wide "safety margin" is present between the melt temperature of the
melt-cast binder and the autoignition temperature of the melt-cast
composition. TNT has a melting point of about 80.9.degree. C., and
COMP B has an autoignition temperature of 167.degree. C., giving a
reasonably wide safety margin between the binder melting
temperature and the autoignition temperature. On the other hand,
many mononitro-substituted and dinitro-substituted arenes have
melting points exceeding that of TNT, thereby narrowing the safety
margin for melt-casting. For example, dinitroanisole has a melting
point of 94.degree. C.
[0011] The inventors have also discovered a way of overcoming this
drawback by combining with the melt-cast binder a processing aid
selected from the group consisting of alkylnitroanilines and
arylnitroanilines. The processing aid combines with the melt-cast
binder to lower the overall melting temperature of the melt-cast
composition, preferably into a range of from 80.degree. C. to
90.degree. C., while raising the autoignition temperature,
preferably to about 149.degree. C. (300.degree. F.) composition to
widen the safety margin.
[0012] Additionally, in accordance with the present melt-cast
composition, the high impact and shock sensitivity commonly
associated with melt-cast explosives such as COMP B are mitigated
by providing at least a portion of the energetic filler (e.g., RDX)
in a fine powder form. It has been discovered by the inventors that
the provision of the energetic filler in fine powder form lowers
the shock and impact sensitivities of the melt-cast composition.
Fine powders have high surface area relative to coarse material.
Fine powders stay suspended in the melt phase significantly better
than coarse material and will not settle out of the binder as
rapidly. This mitigates the formation of a surface-rich melt phase
and the formation of voids and cracks.
[0013] This invention is also directed to ordnances and munitions
in which the melt-cast composition of this invention can be used,
including, by way of example, mortars, grenades, artillery shells,
warheads, and antipersonnel mines.
[0014] These and other objects, aspects and advantages of the
invention will be apparent to those skilled in the art upon reading
the specification and appended claims which explain the principles
of this invention.
DETAILED DESCRIPTION OF THE INVENTION
[0015] The melt-cast explosive of this invention includes at least
the following: at least one mononitro-substituted and/or
dinitro-substituted arene melt-cast binder, at least one
N-alkylnitroaniline and/or N-arylnitroaniline processing aid,
coarse oxidizer particles, and an energetic filler (e.g., RDX
and/or HMX) present at least in part as a fine powder.
[0016] Generally, the melt-cast composition comprises from 25 wt %
to 45 wt %, more preferably from 30 wt % to 40 wt %, and more
preferably about 33.75 wt % of at least one melt-cast binder.
Exemplary melt-cast binders suitable for this invention include
mononitro-substituted and dinitro-substituted phenyl alkyl ethers
having the following formula: 1
[0017] wherein one or two members selected from R.sub.1, R.sub.2,
R.sub.3, R.sub.4, and R.sub.5 are nitro (--NO.sub.2) groups, the
remaining of R.sub.1 to R.sub.5 are the same or different and are
preferably selected from --H, --OH, --NH.sub.2, NR.sub.7R.sub.8, an
aryl group, or an -alkyl group (such as methyl), R.sub.6 is an
alkyl group (preferably a methyl, ethyl, or propyl group), R.sub.7
is hydrogen or an alkyl or aryl group, and R.sub.8 is hydrogen or
an alkyl group.
[0018] 2,4-dinitroanisole (2,4-dinitrophenyl-methyl-ether) and
2,4-dinitrophenotole (2,4-dinitrophenyl-ethyl-ether) are examples
of dinitro-substituted phenyl alkyl ethers suitable for use in the
present melt-cast composition, while 4-methoxy-2-nitrophenol is an
example of an exemplary mononitro-substituted phenyl alkyl ether.
2
[0019] DNAN, along with fine, high surface area material, has been
found (and 2,4-dinitrophenotole and 4-methoxy-2-nitrophenol are
also believed) to exhibit less tendency to shrink and crack than
TNT. The reduced shrinkage and cracking of DNAN is believed to be
attributable to the fact that DNAN does not crystallize as easily
as TNT during solidification that follows melt-casting.
[0020] As referred to herein, "arenes" encompass arene derivatives
such as phenols and aryl amines. For example, mononitro-substituted
and dinitro-substituted arene melt-cast binders suitable for use
with this invention include nitrophenols, such as meta-nitrophenol,
para-nitrophenol, and 2-amino-4-nitrophenol; dinitrophenols, such
as 2,4-dinitrophenol and 4,6-dinitro-o-cresol; nitrotoluene and
dinitrotoluenes, such as 2,4-dinitrotoluene; mononitroanilines,
such as ortho-nitroaniline, meta-nitroaniline, para-nitroaniline;
and dinitroanilines, such as 2,4-dinitroaniline and
2,6-dinitroaniline. As referred to herein, arenes also include
polycyclic benzenoid aromatics such as mononitronaphthalenes and
dinitronaphthalenes (e.g., 1,5-dinitronapthalene).
[0021] The mononitro-substituted and dinitro-substituted arenes
generally have a much lower toxicity than TNT, particularly when
the arenes do not contain --OH and/or --NH.sub.2 functionalities.
Thus, in many instances the use of mononitro-substituted and
dinitro-substituted arenes often simplifies handling and reduces
the costs associated with manufacturing the melt-cast
explosive.
[0022] The processing aid of this invention preferably is one or
more N-alkyl-nitroanilines and/or N-aryl-nitroanilines having the
following formula: 3
[0023] wherein R.sub.6 is hydrogen, R.sub.7 is an unsubstituted or
substituted hydrocarbon (e.g., straight-chain alkyl, branched
alkyl, cyclic alkyl, or aryl group), and at least one of R.sub.1 to
R.sub.5 is a nitro group, the remaining of R.sub.1 to R.sub.5 are
the same or different and are preferably selected from --H, --OH,
--NH.sub.2, NR.sub.8R.sub.9, an aryl group, or an -alkyl group
(such as methyl), R.sub.8 is hydrogen or an alkyl or aryl group,
and R.sub.9 is hydrogen or in alkyl group. Exemplary
N-alkyl-nitroaniline processing aids include the following: 4
[0024] Examples of aryl-nitroaniline processing aids include the
following: 5
[0025] The concentration of the processing aid is selected in order
to widen the "safety margin" at which the melt-cast composition can
be melt-poured without significant threat of autoignition of the
composition. The processing aid generally acts to lower the melting
point of the mixture of melt-cast binder and processing aid towards
(but not necessarily to) its eutectic point. By controlling the
amount of the processing aid, the melting point of the mixture of
melt-cast binder and processing aid can be adjusted into a range of
80.degree. C. to 110.degree. C. that generally characterizes
melt-cast materials. More preferably, the melting point is adjusted
to 80.degree. C. to 90.degree. C., and more preferably about
86.degree. C. Simultaneously, the processing aid has been found to
raise the autoignition (or exotherm) temperature of the melt-cast
composition, thereby widening the safety margin between the melting
temperature and the autoignition temperature of the melt-cast
composition. While not wishing to be bound by any theory, it is
postulated that there is a possibility that the processing aid may
also impart a secondary benefit of functioning as a NO
scavenger.
[0026] The concentration of the processing aid can be selected by
taking into account the amount of melt-cast binder in the overall
melt-cast composition, the purity of the melt-cast binder, and the
nitrogen content of the melt-cast binder. Generally, the melt-cast
composition can include from about 0.15 wt % to about 1 wt %
processing aid based on the total weight of the melt-cast
composition. More than 1 wt % of the processing aid lowers the
temperature of the melt-cast binder/processing aid mixture below
about 80.degree. C.
[0027] Representative inorganic materials that can be used as the
coarse oxidizer particles in the present melt-cast explosive
composition include perchlorates, such as potassium perchlorate,
sodium perchlorate, and ammonium perchlorate; and nitrates, such as
potassium nitrate, sodium nitrate, ammonium nitrate, copper nitrate
(Cu.sub.2(OH).sub.3NO.sub.3, and hydroxylammonium nitrate (HAN);
ammonium dinitramide (ADN); and hydrazinium nitroformate (HNF).
Organic oxidizers having excess amounts of oxygen available for
oxidizing the melt-cast binder can also be used. An example of a
suitable organic oxidizer is CL-20. The coarse particles preferably
have particle diameters, on average, on the order of from about 20
.mu.m to about 600 .mu.m, more preferably 200 .mu.m to 400 .mu.m,
and still more preferably about 400 .mu.m. Particles having an
average diameter of less than about 20 .mu.m are DoD/DoT explosive
class 1.1, and therefore highly detonable and sensitive. The coarse
oxidizer particles preferably constitute from 10 wt % to 55 wt %,
more preferably from 20 wt % to 45 wt %, and still more preferably
about 35 wt % of the overall melt-cast composition.
[0028] Similar to COMP B, which contains RDX as an energetic
filler, the melt-cast explosive composition of this invention also
contains at least one energetic filler. In the present melt-cast
explosive composition, the energetic filler can be RDX, a nitramine
other than RDX, or a combination of RDX and other nitramines.
Representative nitramines that may be used in accordance with this
invention include 1,3,5,7-tetranitro-1,3,5,7-tetr- aaza-cyclooctane
(HMX), 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetra-
cyclo-[5.5.0.0.sup.5,90.sup.3,11]-dodecane (HNIW), and
4,10-dinitro-2,6,8,12-tetraoxa-4,10-diazatetracyclo-[5.5.0.0.sup.5,90.sup-
.3,11]-dodecane (TEX). In addition or as an alternative to the use
of these nitramines, other energetic materials can be used in the
present melt-cast composition, including, by way of example,
nitroguanidine (NQ), 1,3,5-triamino-2,4,6-trinitrobenzene (TATB),
1,1-diamino-2,2-dinitro ethane (DADNE), 1,3,3-trinitroazetidine
(TNAZ), and 3-nitro-1,2,4-triazol-5-one (NTO).
[0029] The overall weight percentage of the melt-cast explosive
composition attributed to the energetic filler is preferably not
more than 60 wt %, more preferably in a range of from 20 wt % to 60
wt %, more preferably in a range of from 30 wt % to 40 wt %.
[0030] It has been discovered by the inventors that the shock and
impact sensitivity of the melt-cast explosive can be reduced by
including a substantial portion of the energetic filler in a fine
powder form, preferably having particle sizes in a range of from
about 2 .mu.m to about 10 .mu.m, more preferably about 2 .mu.m.
However, an excess amount of fine powder energetic filler in the
melt-cast composition can adversely affect the pourability of the
composition. Generally, about 18 wt % to about 54 wt % of the
composition should be fine powder energetic filler. The remainder
of the energetic filler in the melt-cast composition can have
larger particle sizes, such as on the order of about 100 .mu.m, to
ensure that the composition remains melt-pourable.
[0031] According to one preferred embodiment, the composition
comprises 34 wt % dinitroanisole (DNAN), 0.25 wt %
N-methyl-p-nitroaniline (MNA), 30 wt % of 400 .mu.m ammonium
perchlorate (AP), 5 wt % of 100 .mu.m RDX, and 30.75 wt % of 2
.mu.m RDX.
[0032] Additional ingredients can also be introduced into the
melt-cast composition of this invention. For example, a
particularly desirable additional ingredient comprises reactive
metals, such as aluminum, magnesium, boron, titanium, zirconium,
silicon, and mixtures thereof. Reactive metals are particularly
useful in applications in which the melt-cast explosive is
submerged or otherwise exposed to large amounts of water.
[0033] Preferably, the melt-cast composition of this invention is
substantially free of polymeric binders conventionally found in
pressable and extrudable energetic materials, since an undue amount
of these polymeric binders can lower the energy (especially for
nonenergetic polymer binders) and reduce the melt-pourability (by
increasing the viscosity) of the melt-cast explosive.
EXAMPLES
[0034] The following examples illustrate embodiments which have
been made in accordance with the present invention. Also set forth
are comparative examples prepared for comparison purposes. The
inventive embodiments are not exhaustive or exclusive, but merely
representative of the invention.
[0035] Unless otherwise indicated, all parts are by weight.
[0036] Examples 1 and 2 were prepared as follows. The
dinitroanisole (DNAN) was introduced into a melt kettle and heated
to melt the DNAN into a liquid state. The processing aid
N-methyl-p-nitroaniline (MNA) was also added at this time. While
stirring, fine RDX was added at a sufficiently slow rate to
facilitate thorough wetting of the RDX fine powder. Coarse RDX was
then added by stirring, followed by the ammonium perchlorate
inorganic oxidizer, which was also added while stirring. Once
homogeneous, stirring was increased for another hour, then poured
into an ordnance and allowed to cool at ambient conditions.
[0037] Comparative Example A and COMP B were prepared under similar
conditions, but without the processing aid.
1 TABLE I Comparative Example 1 Example 2 Example A COMP B DNAN
33.75 27.5 28 MNA 0.5 0.5 Ammonium 25 12 12 perchlorate (AP) RDX
(1.8 .mu.m) 30.75 30 30 RDX (100 .mu.m) 10 30 30 59.5 TNT 39.5
Paraffin 1.0 Cards 155 188 188 203 Energy of 9.2 9.5 9.5 9.5
Detonation MP(.degree. C.) 86 91 93 81 Exotherm (.degree. C.) 167
167 139 167 Safety Margin 81 76 46 86
[0038] The card gap test measures shock sensitivity by loading a
sample into a card gap pipe and setting off an explosive primer a
predetermined distance from the sample. The space between the
primer and the explosive charge is filled with an inert material
such as PMMA (polymethylmethacrylate). The distance is expressed in
cards, where 1 card is equal to 0.01 inch (0.0254 cm), such that
100 cards equal 1 inch (2.54 cm). If the sample does not explode at
100 cards, for example, then the explosive is nondetonable at 100
cards. Thus, the lower the card value, the lower the shock
sensitivity.
[0039] Example 1 exhibited a card gap value of 155, which is almost
20% lower than Comparative Example A (188 cards) and more than 20%
lower than COMP B (203 cards).
[0040] Additionally, a comparison of Example 2 and Comparative
Example A shows that the presence of MNA in the inventive
composition lowered the melting temperature and raised the exotherm
temperature, while not adversely affecting card gap. Hence, the
"safety margin" at which Example 2 can be melt-cast is increased by
30.degree. C. over that of Comparative Example A.
[0041] The foregoing detailed description of the preferred
embodiments of the invention has been provided for the purpose of
explaining the principles of the invention and its practical
application, thereby enabling others skilled in the art to
understand the invention for various embodiments and with various
modifications as are suited to the particular use contemplated. The
foregoing detailed description is not intended to be exhaustive or
to limit the invention to the precise embodiments disclosed.
Modifications and equivalents will be apparent to practitioners
skilled in this art and are encompassed within the spirit and scope
of the appended claims.
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