GB2504050A

GB2504050A - High oxygen content explosive compositions

Info

Publication number: GB2504050A
Application number: GB9524750A
Authority: GB
Inventors: Paul C Braithwaite; Gary K Lund
Original assignee: Thiokol Corp
Current assignee: ATK Launch Systems LLC
Priority date: 1995-12-04
Filing date: 1995-12-04
Publication date: 2014-01-22
Anticipated expiration: 2015-12-04
Also published as: GB2504050B; GB9524750D0

Abstract

High explosive compositions having favorable oxygen balances for use in confined volume, underwater, underground, and other limited oxygen environments, are disclosed. The disclosed explosives include an energetic binder, an oxidizer, a reactive 'metal, and a high explosive. The ingredients are combined in. concentrations such that the explosive composition has an equivalence ratio in the range from 1 to 3 as determined by the NASA Lewis thermo-chemical equilibrium computer software SP-273. The resulting explosives do not rely on external oxygen to combust the metal efficiently as do conventional warhead fills.

Description

HIGH OXYGEN CONTENT EXPLOSIVE COMPOSITIONS

Field of the Invention

The present invention relates to enhanced performance explosive compositions. More particularly, the present invention is directed to highly oxygenated high explosive compositions containing an energetic polymer, an oxidizer, a reactive metal, and a high explosive for use in applications where there is little available external oxygen.

Background of Invention

Explosives and explosive devices must meet many rep]ire-nents if they are to achieve optimal effectiveness in confined volume, underwater, or underground applications where there is little available external oxygen. These applications include structurally damaging bunkers, bridge piers, ships and underwater mines, and heaving runways, berms, and embankmerits.

Unfortunately, conventional warheads and explosives are not effective in these low-oxygen availability applications for three reasons: (1) a significant amount of energy remains unused due to the incomplete combustion of reactants, (2) the rate of energy release is too high to cause maximum damage, and (3) the duration of high temperature is too short to cause complete burning of the reactive metal particles, which in an unreacted condensed phase act as an energy sink.

A reactive metal, such powder, is commonly added to composite explosives in quantities ranging from 5 to weight percent. The addition of aluminum to explosives increases the density and theoretically increases the amount of heat released during detonation. A large heat release is critical to maximum expansion of product gases during and S after detonation. This relates directly to the amount of work an explosive is capable of performing in a confined volume application. High temperature is also necessary for the complete reaction of aluminum or other metallic constituents.

Unfortunately, even under ideal condition! not all of the aluminum is reacted during detonation of a typical composite explosive. As a result, significant amounts of available energy remain unused. The unreacted aluminum acts as a heat sink and reduces the amount of energy available from the detonation. When little external oxygen is available, problems associated with metal reactivity are increased.

Conventional explosives do not function efficiently in confined volume applications because their rate of energy release is too high. It is desirable that the explosive in a warhead contain significant amounts of high-energy, high-density materials to minimize the size of the warhead.

However, high energy-density materials such as}ThIX, RDX, and TNT have high detonation velocities, which are desirable in shaped charge and metal accelerating applications, but not in confined volume applications For confined volume applica-tions, relatively slow rates of energy release are much more desirable, especially for, damaging runways and reinforced concrete bunkers. Lonaer duration tiñies (milliseconds instead 4' of microseconds) produce much more damage to runways, rein-forced bunkers, and similar targets.

Rapid volume expansion resulting from high-energy release rates also produces inefficient metal reaction due to the short duration of high temperatures in the reaction zone. If the duration of the high temperature experienced by a metallic particle is too short, even though the temperature is well above the combustion temperature, the particle will not burn completely due to insufficient time f or diffusion and heat transfer. Therefore, to optimize the reaction of metals used in coTrposite explosives for confined volume applications, it is necessary to increase the time at which high temperatures are maintained.

It will be appreciated that there is a need in the art for new explosive compositions having a prolonged combustion rate which produces more useful work on the target. There is a further need to provide explosive formulations containing sufficient oxygen to burn the reactive metals and thereby increase the amount of heat and lengthen the time the explo-sive can do its work.

Such enhanced performance explosive compositions are disclosed and claimed herein.

Summary of the Invention

The present invention is directed to high explosive compositions having favorable oxygen balances for use in confined volume, underwater, underground, and other limited 1' oxygen enyironments. The explosives include an energetic binder, an oxidizer, a reactive metal, and a high explosive.

The ingredients are combined in concentrations such that the explosive composition has an equivalence ratio of fuelf oxygen in the range from 1 to 3 as determined by the NASA Lewis thermochemical equilibrium computer software SP-273. See, Sanford Gordon and Bonnie 3. McBride, "Computer Program for Calculation of Complex Chemical Equilibrium Compositions, Rocket Performance, Incident and Reflected Shocks, and Chapman-Jouguet Detonations" NASA SP-273, Interim Revision, March 1976, which is incorporated herein by reference. As used herein, the equivalence ratio is calculated based upon the oxidation states of each element occurring in the reac-tants. A summation is made of the oxidation states per kilogram of the total oxidant or total fuel. The equivalence ratio is calculated from this information.

The NASA Lewis SP-273 software utilizes several equa-tions, described below, to calculate the equivalence ratio.

The total reactant may be composed of a number of reactants and each of these may be specified as an oxidant or a fuel.

If the total reactant contains more than one oxidant, these oxidants may be combined into a total oxidant by specifying the relative proportion of each oxidant. Similarly, if the total reactant contains more than one fuel, they may be combined into a total fuel by specifying the relative propor-tions of each fuel. The equivalence ratio is calculated according to the following equation: Equivalence ratio = _____ j=1 Where: 1 equals the number of fuel species (elements with positive oxidation states, a, is the mole fraction of i1 fuel species in the S explosive, V1 is the oxidation state of the ith fuel species, in equals the number of oxidizing species (elements with negative oxidation states), bj is the mole fraction of 1th oxidizing species in the explosive, is the oxidation state of the jth oxidizing species.

From the equation, the first step is to calculate the mole fraction of each element in the composition. Next, the commonly occurring oxidation state for each element is determined. Finally, the sum of all fuel species (i.e., those with a positive oxidation state) multiplied by the mole fraction for the fuel species is divided by the sum of all oxidizing species (i.e., those with a negative oxidation state) multiplied by the mole fraction for the oxidizing species.

Using the methodology of NASA SP-2?3 the equivalence ratio of the common explosive 2,4,6-trinitrotoluene (TNT) is

II

calculated to be 2.75. The composition of TNT and the oxidation states of the individual atoms are shown below: Number Oxidation S Element of Atoms State carbon 7 +4 Hydrogen 5 +1 Nitrogen 3 Inert Oxygen 6 -2 Therefore the equivalence ratio for TNT equals: (7x4 + Sxl)/(6x2) or 2.75.

Another common explosive consists of 80% by weight TNT and 20% aluminum. The equivalence ratio for this explosive is found to be 3.276. The additional aluminum, without an oxidizer, increases the equivalence ratio. The composition of this explosive and the oxidation states of the individual atoms are as follows: Mole Oxidation Element Percent State carbon 30.30 +4 Hydrogen 21.64 +1 Aluminum 9.11 +3 Nitrogen 12.98 Inert Oxygen 25.97 -2 Therefore the equivalence ratio for 80% TNT/20% aluminum equals: (0.3030x4 + 0.2164x1 + 0.0911x3)/(0.2597x2) or 3.276.

Explosive compositions with low equivalence ratios as defined herein, have reasonable oxygen balances despite containing substantial quantities of reactive metal, such as aluminum, and moderate amounts of oxidizer, such as aimnonium perchiorate. The resulting explosives do not rely on external oxygen to conibust the metal efficiently as do conventional warhead fills.

Brief Description of the Figures

Figure 1 is a graph illustrating equilibrium flame temperature versus the fuel to oxygen ratio for two composite explosives and two propellants prepared with an energetic binder and with an inert binder.

Detailed Description of the Invention

The present invention is directed to high explosive compositions having favorable oxygen balances for use in confined volume, underwater, underground, and other limited oxygen environments. The explosives include an energetic binder, an oxidizer, a reactive metal, and a high explosive.

The ingredients are combined in concentrations such that the explosive composition has sufficient oxygen to combust the reactive metal without the need for external oxygen.

Typical energetic binders which can be used in the present invention include PGN (polyglycidyl nitrate), poly-1' NMMO (nitratoinethyl-methyloxetane), GAP (polyglycidyl azide), 9DT-NIDA (diethyleneglycol-triethyleneglycol-nitraminodiacetjc acid terpolymer), poly-BANO (poly(bis(azidomethyl)oxetane)), poly-AMNO (poly(azidomethyl-methyloxetane)), poly-NAMNO S (poly(nitraminomethyl-methyloxetane)), poly-BFMO (poly(bis(difluoroaininomethyl)oxetane)) , poly-DFNO (poly(difluroamincmethylmethyloxetane)), and copolymers and mixtures thereof. Those skilled in the art will appreciate that other known and novel energetic binders not listed above may be used in the present invention. Suitable energetic binders used according to the present invention have a high density, relatively high heat of formation. Binders with the most utility have significant oxidizing moiety content, such as fluorine or oxygen. The energetic binder will typically be present in a concentration from 10 wt.% to 40 wt. %, and preferably from 15 wt. % to 30 wt. %.

Equilibrium thermochemical calculations indicate signifi-cant increases in temperature and pressure are produced when the inert binder system in a typical composite explosive is replaced with an energetic polymer system. In particular, the data shown in Table 1 illustrate the increase in temperature and pressure predicted when the hydroxy terminated polybuta-diene (HTPB) binder system of PBXN-109 is replaced with a PGN binder system. Conventional PBXN-109 is comprised of the following ingredients: 20 wt. % Al, 64 wt. % RDX, 16 wt. % binder system containing HTPB, DOA, and IPDI. The equilibrium temperature calculation was performed using NASA Lewis SP-273 ----8-at 500,000 psi. The C-J (Chapman-Jouguet) detonation pressure was calculated using TIGER thermochemical equilibrium software with BKW equation of state (Stanford Research Institute, Menlo Park, California, Publication Number ZiOG).

S

Table 1

Influence of Binder System on Equilibrium Temperature and Calculated C-J Detonation Pressure of PBXN-109 Equilibrium Detonation Composition Temp. (°K) Pressure (katm) PBXN-109 (HTPB) 3348 211.1 PBXN-109 (PGN) 4125 287.0 The binder may also contain up 75%, by weight, of a plasticizer such as DOA (dioctyladipate or (2-ethylhexyl)-adipate), lOP (isodecylperlargonate), DOP (dioctyiplithalate), DOM (dioctylmaleate), DBP (dibutylphthalate), oleyl nitrile, or mixtures thereof. Energetic plasticizers may also be used, such as BDNPF/BDNPA (bis(2,2-dinitropropyl)acetal/bis(2,2-dinitropropyl)formal), TNETN (trimethylolethanetrinitrate), TEGDN (triethyleneglycoldinitrate), DEGDN (diethyleneglycol-dinitrate), NG (nitroglycerine), BTTN (butanetrioltrinitrate), alkyl NENA's (nitratoethylnitramine), or mixtures thereof.

Typical high explosives which can be used in the present invention include known and novel nitramines such as CL-20 (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo- [5.5.0. o5'9.03")-dodecane), RDX (1, 3,5-trinitro-l,3, 5-triazacy- clohexane), HMX (1,3,5, 7-tetranitro-1, 3, 5,7-tetraazacyclo---9 -. octane), TEX (4, 1o-dinitro-2, 6,8, 12-tetraoxa-4,10-diazatetra- cyc1o[5.5.O.O5.03'"3dodccane), NTO (3-nitro-1,2,4-triazol-5-one), MQ (nitroguanidine), TAG nitrate (triaminoguanidinium trinitrate), PETN (pentaerythritol tetranitrate), TATB (1,3,5- S triamino-2,4, 6-trinitrobenzene), TNAZ (1,3, 3-trinitroazeti- dine), ADN (ammonium dinitramide), DADNE (1,1-diamino-2,2-dinitro ethane), and mixtures thereof. Those skilled in the art will appreciate that other known and novel high explosives not listed above may also be used in the present invention.

The high explosive will typically be present in a concentra-tion from 10 wt. % to 50 wIn % and preferably from 15 wt. % to wt. % of the total explosive composition.

Reactive metals are added to the explosive compositions of the present invention to achieve high heats of reaction.

The reactive metal is preferably aluminum or magnesium, although other reactive metals may also be used such as boron, silicon, titanium, zirconium, or mixtures thereof, Selected metal alloys may also be used, such as aluminum/magnesium and aluiuinum/ lithium alloys. These types of alloys have been used successfully in the solid rocket propellant industry. Such alloys react more completely than pure metals by virtue of the increased reactivity and lower ignition and cutoff tempera-tures. Increased metal reactivity further improves overall combustion efficiency which translates into the generation of greater amounts of heat during the reaction of the explosive.

As used herein, reactive metals also include metal hydrides such as titanium and zirconium hydrides. The reactive metal r]0 -1' I content of the explosive compositions within the scope of the present invention typically ranges from 15 wt. % to 50 wt. %, more preferably from 20 wt. * to 35 wt. %.

The oxidizer is preferably AP (ammonium perchlorate) or S AN (amnioniun nitrate), although other oxidizers can be used such as RAN (hydroxyl-anunonium nitrate), ADN (anunonium dinitramide), lithium perchlorate, potassium perchlorate, lithium nitrate, or mixtures thereof. Useful oxidizers are characterized by high density and oxygen content. The oxidizer will typically be present in a concentration from 10 wt. % to 40 wt. %, more preferably from 15 wt. % to 35 win %, and most preferably 20 wt. % to 30 wt. % of the total explo-sive composition. In explosives compositions containing highly oxygenated or fluorinated polymer systems and a low energy explosive, such as TEX or NTO, no oxidizer may be needed to provide the desired oxygen balance.

The benefits of proper selection of ingredients to be used in confined volume or limited oxygen applications are further illustrated in Figure 1. In Figure 1, the equilibrium flame temperature versus the equivalence ratio for two composite explosives and two propellants are compared. The two explosives and two propellants differ in that one contains an energetic binder (PGN) and one contains an inert binder (HTPB). The ratio of nitramine to metal and oxidizer to metal was varied for each composition while holding the total solids level for each formulation constant. -i_i-

For each composition illustrated in Figure 1, the flame temperature was predicted to increase as more metal was added, at the expense of the nitramine or oxidizer, until the metal content became too high at which point the predicted tempera- ture drops. However, the maximum temperature for the explo-sive and propellant containing the energetic binder was much higher than the corresponding inert binder formulation. In addition, the energetic binder dramatically lowered the fuel to oxygen ratio for both the explosive and propellant. Higher flame temperatures and lower fuel to oxygen ratios are both desirable characteristics for compositions which will be effective in destroying confined volume targets.

Results of theoretical calculations for several explosive compositions containing HMX are reported in Table 2. Similar results are obtained when other high explosives are used.

These data indicate that the explosive compositions within the scope of the present invention have high temperatures and favorable oxygen balances relative to three current explo-sives, TNT, Tritonal, and PBXN-l09, used against underground targets. High reaction temperatures and favorable fuel to oxygen ratios are both important factors in developing explosive compositions which will efficiently combust the metal additive. Additionally, the density of the explosive compositions described herein is considerably more dense than baseline explosives. The hiqher density makes it possible to load the same weight of explosive in smaller devices or a greater quantity nf expJosive in the same volume. This is advantageous to producing more portable battlefield armament or enhanced guidance devices.

Table 2

Deton. Reaction Density Equiv. Pressure Temperature (°K) Composition (glee) Ratio (kBar) 1000 psi 14.7 psi TNT 1.65 2.75 228.5 2009 1048 Tritonal 1.79 3.28 303.6 2803 2011 PBXN-109 1.67 3.65 280.6 2630 1884 A 1.88 1.77 386.5 3807 2569 B 1.90 2.00 386.4 3687 2444 C 1.93 2.27 372.6 3296 2347 D 1.96 2.64 366.9 2993 2363 Explosive compositions A-U included the following ingredients expressed in weight percent:

Table 3

PGN

Composition Binder HMX Al AP A 25 20 24 31 B 25 20 29 26 C 25 20 34 21 ID 25 20 39 16 The PGN binder consisted of the following ingredients ex-pressed as weight percent of the total explosive composition.: -13-H 14.l9wt. % PGN, 8.0 wt. % DEGON, 0.25 sit. % 4-NDPA, 0.50 wt.

% MNA, 2.00 wt. % Desmodur® N-100 (a polyisocyanate curative obtained from Mobay), and 0.06 wt. % TPTC (triphenyl tin chloride).

The present invention is further described in the following nonlimiting examples.

Example 1

A series of explosive compositions were prepared in 10-gram quantities. The compositions were mixed and cast according to conventional explosives processing techniques.

The explosive compositions had the following ingredients expressed in weight percent:

PGN

Composition Binder HMX TEX CL-20 Al AP 1-a 54.33 45.67 ---- 1-b 33.37 28.06 --38.57 - 1-c 24.08 20.24 --27.84 27.84 1-d 52.25 -47.75 --- l-e 31.55 -28.82 -39.63 - 1-f 22.135 -20.22 -27.81 29.835 i-g 54.33 --45.67 -- 1-h 32.24 --27.10 40.66 - 1-i 24.08 --20.24 30.367 25.31 The PGN binder consisted of 36.59 wt. % PGN, 55.05 wt. %, DEGDN, 0.97 sit. % 4-NDPA (4-nitrodiphenylamine), 2.44 wt. % MNA (N-methyl-p-nitroanhline), and 0.12 sit. % acid scavenger (N,N,N' ,n'-tetramethyl-l, 8-naphthalenediamine, obtained from Aldrich). The material was tested to determine its safety characteristics. Safety tests were run using standard methodologies common the those skilled in the art. It should noted that TC (Thiokol Corporation) tests are 50% fire values and ABL (Allegheny Ballistics Laboratory) numbers are thresh-old initiation values. The results were as follows: Impact Friction ESO SBAT DSC

ABL TC ABL TC

(cm) (lb) (psi@ftfs) (3) (°F) (°C) 1-a 21 >64 240@8 6.47 254 177 1-b 11 >64 l00@6 >0.10 253 127 1.-c 3.5 60.8 50@6 1.53 253 186 1-d 26 >64 240@6 2.23 253 187 l-e 41 >64 370@8 0.73 253 190 1-f 3.5 56.2 25@6 0.31 266 194 1-g 13 >64 800@8 1.17 259 188 1-h 13 63 100@3 1.41 259 191 1-i 6.9 59.6 25@4 0.19 279 187 ESD = Electrostatic Discharge SBAT = Simulated Bulk Autoignition Temperature.

DSC = Differential Scanning Calorimeter, base line departure.

-15 -These data are typical of high performance explosives. As the AP content increased, the sensitivity to ignition via friction increased.

Example 2

several 600 gram explosive composition mixes were processed in a 1-pint mixer. The compositions were mixed and cast according to conventional explosives processing tech-niques. The compositions had the following ingredients expressed in weight percent:

PGN

Composition Binder RMX TEX CL-20 Al A? 2-a 25 20 --29 26 2-b 25 -20 -27.5 27.5 2-c 25 --20 30 25 The PGN binder consisted of the following ingredients cx-pressed as weight percent of the total explosive composition: 14.19 wt. % PGN, 8.0 wt. % DEGDN, 0.25 wt. % 4-NDPA, 0.50 wt.

% MNA, 2.00 wt. % Desmodur® 11-100, and 0.06 wt. % TPTC. The viscosity of the explosive compositions was very low (0.8]CP) and the explosive compositions were not vacuum cast. The Al' was unground (about 200 g) and the Al was about 15 i.

The explosive compositions were loaded into standard NOL (Naval ordnance Laboratory) card gap pipes (5-1/2 inches long and 1-3/8 inches inside diameter). In the standard "card gap" test, an explosive primer is set off a certain distance from the explosive. The space between the primer and the explosive charge is filled with an inert material such as PNMA (poly-methylxaethacrylate). The distance is expressed in cards, where 1 card is equal to 0.01 inch such that 70 cards is equal to 0.7 inches. If the explosive does not detonate at 70 cards, for example, then the explosive is insensitive at 70 cards. These pipes were also instrumented to allow the detonation velocity to be determined. The results of these tests and tests on the aluminized explosive PBXN-109 are summarized below: Composition Cards Result PBXN-109 70 sustained detonation, Vd=7685 rn/s PBXN-109 150 Sustained detonation, Vd=7712 nt/s 2-a 35 sustained detonation, Vd=7432 nt/s 2-a 70 Sustained detonation, Vd=7180 ni/s 2-b 35 Sustained detonation, Vd=5579 itt/s 2-b 70 No detonation 2-c 35 Sustained detonation, Vd=6702 rn/s 2-c 70 Sustained detonation, Vd=6846 nt/s These results show that the tested compositions according to the present invention have detonation velocities lower than PBXN-109. The lower detonation velocity renders the explo-sives more suitable for use in the low-oxygen availability applications discussed in the background section, above.

Example 3

The explosive compositions disclosed in Example 2 were processed in a 1-pint mixer cast into 3.875 inch diameter hemispheres for subsequent testing in an air blast configura- tion to determine blast overpressure relative to TNT and PBXN- 109. The testing and results are discussed in Example 8.

Example 4

The explosive compositions disclosed in Table 3 were processed in a 1-pint mixer and cast into hemispheres accord-ing to the procedure of Example 3 to evaluate the effects of changes in Al/AP ratios (or fuel/oxygen ratio). All mixes were processed at 75% solids, by weight, and were identical, other an the Al and AP percentages. The compositions had the following ingredients expressed in weight percent: PGN Equiv.

Composition Binder HMX Al Al? Ratio 4-a 25 20 24 31 1.77 4-b 25 20 29 26 2.00 4-c 25 20 34 21 2.27 4-d 25 20 39 16 2.60 From each mix, one 3.875-inch diameter hemisphere was cast and cured for subsequent testing in an air blast configuration to determine blast overpressure relative to TNT and PBXN-109.

The testing and results are discussed in Example 8.

I

Example S

Two explosive compositions were processed in a 1-pint mixer according to the procedure of Example 2 (composition 2-b), except that a blended nitramine (TEX and}INX) was used.

The compositions had the following ingredients expressed in weight percent:

PGN

Composition Binder JiNX TEX 5-a 25 5 15 27.5 27.5 5-b 25 10 10 27.5 27.5 The PGN binder consisted of the following ingredients ex-pressed as weight percent of the total explosive composition: 14.19 wt. % PGN, 8.0 wt. % DEGDN, 0.25 wt. % 4-NDPA, 0.50 wt.

% NNA, 2.05 wt. % Desmodur® 14-100, and 0.01 wt. % TPTC. Both.

mixes processed easily and had end of mix (EOM) Brookfield viscosities < 3 kP. From each mix, one 3.875-inch diameter hemisphere was cast and cured for subsequent testing in an air blast configuration. The testing and results are discussed in

Example 9.

Example 6

Two explosive compositions were processed in a 1-pint mixer according to composition 3-b of Example 3, with one composition containing TEX and the other containing NTO instead of TEX. from each mix, one 3.875-inch diameter 19 -hemisphere was cast and cured for subsequent testing in an air blast configuration. Because these explosives are insensi-tive, a smaller concentric hemisphere, to be filled with a PGNJCL-20 explosive composition, was cast into the larger hemisphere. The PGNfCL-20 explosive contained 70 wt. % CL-20, 26.24 cit. % PGN, 0.25 wt. % 4-NDPA, 0.5 cit. % MNA, 3.0 cit. % Desmodur® N-100, and 0.01 cit. % TPB (triphenyl bismuth). The smaller hemisphere had a diameter of approximately 2 inches.

A glass sphere was used to create the smaller hemisphere cavity during casting.

The purpose of these mixes is to obtain a direct compari-son of the performance of TEX and NTO in an airbiast test.

The testing and results are discussed in Example 9.

Example 7

Because of the excellent overall performance of mix 4-d of Example 4, additional mixes of high aluminum explosives were processed according to conventional explosives processing techniques. The compositions had the following ingredients expressed in weight percent:

PGN

Composition Binder HNX CL-20 Al AP 7-a 25 -20 40 15 7-b 25 20 -39 16 t-20 -Two mixes of composition 7-a were processed, one was used to cast a 3.875-inch diameter hemisphere and one was used to cast two standard NOL card gap pipes which were instrumented for detonation velocity. The results of the hemisphere test S are discussed in Example 9. One mix of composition 7-b was processed and cast into two standard NOL card gap pipes which were instrumented for detonation velocity. The card gap test results were as follows: composition cards Result 7-a 35 Sustained detonation, Vd=6833 rn/s 7-a 70 Sustained detonation, Vd=7054 rn/s 7-b 35 Sustained detonation, Vd=6856 rn/s 7-b 70 sustained detonation, Vd6874 in/s These data indicate that both compositions have detona-tion velocities which are suitable for explosives designed for the low-oxygen availability applications discussed in the

background section, above.

Example 8

Air blast performance tests were performed on the explosive compositions disclosed in Examples 3 and 4 and on TNT and PBXN-lOY explosive charges similarly cast as a hemisphere. The cast hemispheres were placed on top of a 9-inch by 9-inch steel plate which was 1-inch thick. In the center of the steel plate, a 1-inch diameter hole was drilled 21 -for the booster and blasting cap. The booster consisted of one sheet of Detasheet® A-4, (sold by Dupont, based on PETN) and a 1-inch thick cylinder of detonable propellant. The hemisphere/plate/booster/cap assembly was placed in the ground so that the top of the plate was level with the ground. Also at ground level were transducers placed at locations predicted to experience 100 Psi, 10 psi, and 1 psi overpressure.

The TNT and the TEX charges did not appear to fully detonate while the other charges were clearly detonations as they deformed the witness plates and resulted in significant overpressures. The peak overpressure at 10 feet and 40 feet, expressed in TNT equivalents, and the positive impulse at 10 feet and 40 feet for the explosive compositions is presented

in Table 4.

Peak Positive Overpressure Impulse Composition 10 ft. 40 ft. 10 ft. 40 ft.

PBXN-109 1.14 1.35 0.59 0.62 2-b (TEX) (Did not fully detonate) 2-c (CL-20) 1.48 1.65 0.78 0.89 4-a (HMX) 1.36 1.62 0.70 0.63 4-b (JINX) 1.32 1.31 0.70 0.83 4-c (HNX) 1.33 1.58 0.73 0.78 4-d (JINX) 1.30 1.64 0.78 0.80

Example 9

Air blast performance tests were performed on the explosive compositions disclosed in Examples 5, 6 and 7. The cast hemispheres were placed on top of a 9-inch by 9-inch steel plate which was 1-inch thick. In the center of the steel plate, a 1-inch diameter hole was drilled for the booster and blasting cap. The booster consisted of one sheet of Detasheet A-4, (sold by DuPont, based on PETN) and a 1-inch thick cylinder of a detonable propellant. The hemisphere/-plate/booster/cap assembly was placed in the ground so that the top of the plate was level with the ground. Also at ground level two arrays of pressure transducers (located perpendicular to each other) were placed 4 feet, 10 feet, and feet from the center of the explosive. Because of its insensitive nature, composition 5-a did not fully detonate.

The average overpressure (expressed in TNT equivalents) from all gauges front these tests are shown below: Average Composition Overpressure 5-a (15% TEX) 0.57 5-b (10% TEX) 1.01 6-a (TEX) 1.11 6-b (NTO) 1.16 7-a (CL-20) 1.43 rLtJw LLJ.e £QLS9USiA9, SC WSSS ae appreciacea. that the present invention provides explosive compositions having a prolonged combustion. The present invention further provides explosive formulations containing sufficient oxygen to burn the reactive metals and thereby increase the amount of heat and lengthen the time the explosive can do its work. -. . -r-

Claims

CLAIMS1. An explosive composition comprising: an energetic binder; an oxidizer-; a reactive metal; and a high explosive, wherein the explosive composition has an equivalence ratio in the range from 1 to 3.

2. An explosive composition as defined in claim 1, wherein the explosive composition has an equivalence ratio in the range from 1.5 to 2.5.

3. An explosive compesittQ as. defined in claim 1 or claim 7, wherein the high explosive is selected from CL-20 (2,4,6,8,lO,12-hexanitro-2,4,6,8,1O,l2-hexaazatetracyclo- (5.5.0. &. 03')-dodecane), RDX (1,3, 5-trinitro-l,3,5-triaza- cyclohexane), RNX (1,3,5,7-tetranitro-l, 3, 5,7-tetraazacyclo- octane), TEX (4,10-dinitro-2, 6,8, 12-tetraoxa-4, lO-diazatetra- cyclo{5.5.O.05'9.03"Jdodecane), NTO (3-nitro-1,2,4-triazol-5- one), PETN (pentaerythritol tetranitrate), TATB (1,3,5-tn-amino-2,4, 6-trinitrobenzene), TNAZ (1,3, 3-trinitroazetidine), ADM (ammonium dinitramide), DADNE (l,1-diamino-2,2-dinitro ethane), and mixtures thereof.

4. An explosive composition as defined in any preceding claim wherein the high explosive is present in a concentration from weight percent to 50 weight percent of the explosive composition.S

An explosive composition as defined in clairn4,: -wherein the high explosive is present in a concentration from weight percent to 30 weight percent of the explosive composition.

6. An explosive composition as defined in any precedinq claim wherein the energetic binder is selected from PCN (polygly-cidyl nitrate), poly-NNNO (nitratomethyl-methyloxetane), GAP (polyglycidyl azide), 90T-NIDA (diethyleneglycol-triethylene-- glycol-nitraminodiacetic acid terpolyner), poly-BAXO (poly- (bis(azidomethyl)oxetane)), poly-ANHO (poly(azidomethyl- methyloxetane)), poly-NAXMO (poly(nitraminomethyl-methyl-oxetane)) , and copolymers and mixtures thereof.

7. An explosive composition as defined in any preceding claim wherein the energetic binder is present in a concentration from 10 weight percent to 40 weight percent of the explosive composition.

-26 - 8. An explosive composition as defined in claim 7, wherein the energetic binder is present in a concentration from 15 weight percent to 30 weight percent of the explosive composition.

9. An exp1osiwe composition as defined in any preceding claim wherein the energetic binder further comprises a plasticizer.

10. An explosive composition as defined in claim 9, wherein the plasticizer is selected from BDNPF/BDNPA (bis(2,2-dinitropropyl) acetal/bis(2, 2-dinitropropyl) formal), TMETN (trimethylolethanetrinitrate), TEGDN (triethyleneglycoldini- trate), DEGDN (diethyleneglycol-dinitrate), NG (nitrogly- cerine), BTTN (butanetrioltrinitrate), alkyl NENA's (nitrato-ethylnitraiuine), and mixtures thereof.

11. An explosive composition as defined in claim 9, wherein the plasticizer is selected from DOA (dioctyladipate or (2-ethylhexyl) adipate), 11W (isodecylperlargonate), DOP (dioctylphthalate), DOM (dioctylmaleate), DBP (dibutyl-phthalate), oleyl nitrile, and mixtures thereof.

12. An explosive composition as defined in any preceding claim wherein the reactive metal is selected from aluminum, boron, magnesium, titanium, zirconium, mixtures, and alloys thereof.

-27 - 13. An explosive composition as defined in any preceding claim -wherein the reactive metal is in the form of a metal hydride.

14. An explosive composition as defined in any preceding claim wherein the reactive metal is present in a concentration from weight percent to 50 weight percent of the explosive composition.

15. An explosive composition as defined in claim 14, wherein the reactive metal is present in a concentration from weight percent to 35 weight percent of the explosive composition.

16. An explosive composition as defined in any precedinqclaim wherein the oxidizer is selected from A? (ainmonium perchiorate), AN (ammonium nitrate), HAN (hydroxyl-ammonium nitrate), ADN (ammonium dinitramide), and mixtures thereof.

-28 - 17. An explosive composition comprising: an energetic binder selected from PGN (polyglycidyl nitrate), poly-NMNO (nitratomethyl-methyloxetane), GAP (polyglycidyl azide), 9DT-NIDA (diethyleneglycol-triethyleneglycol-nitraminodiacetic acid terpolymer), poly-BANO (poly(bis(azidomethyl)oxetane)), poly-ANMO (poly(azidomethyl-methyloxetane)) , poly-NAMMO (poly(nitraminomethyl-methyloxetane)), and copolymers and mixtures thereof, wherein the energetic binder is present in a concentration from 10 weight percent to 40 weight percent of the explosive composition; an oxidizer selected from Al' (ammonium perchlorate), AN (ammonium nitrate), HAN (hydroxyl-ainmonium nitrate), ADN (anunonium dinitramide), and mixtures thereof; a reactive metal selected from aluminum, boron, magnesium, titanium, zirconium, alloys thereof, titanium hydride, zirconium hydride, and mixtures thereof, wherein the reactive metal is present in a concentration from 15 weight percent to 50 weight percent of the explosive composition; and a high explosive, wherein the high explosive is present in a concentration from 10 weight percent to 50 weight percent of the explosive composition, and wherein the explosive composition has an equivalence ratio in the range from 1 to 3.

18. An explosive composition as defined in claim 17, wherein the energetic binder further comprises a plasticizer.

19. An explosive composition as defined in claiitj 18, wherein the plasticizer is selected from BDNPF/BDNPA (bis(2,2-dinitropropyl)acetal/bis(2, 2-dinitropropyl)forinal), TMETN (trimethylolethanetrinitrate), TEGON (triethyleneglycoldini- trate), DEGDN (diethyleneglycol-dinitrate), HG (nitrogly- cerine), BTTN (butanetrioltrinitrate), alkyl NENA's (nitrato-ethylnitramine), and mixtures thereof.

20. An explosive composition as defined in claim 18, wherein the plasticizer is selected from DOA (dioctyladipate or (2-ethyihexyl) adipate), ID? (isodecylperlargonate), DOP (dioctylphthalate), DOM (dioctylmaleate), DBP (dibutyl-phthalate), oleyl nitrile, and mixtures thereof.

21. An explosive composition as defined in any pne:.ofclai'ns 17 to 20, wherein the energetic binder is PGN, the oxidizer is AP, the reactive metal is aluminum, and the high explosive is selected from CL-20 (2,4,6,8,lO,l2-hexanitro-2,4,6,8,1O,12--hexaaza- tetracyclo[5.5.0. 0. 03"]-dodecane), ROX (1, 3,5-trinitro-1, 3,5- triazacyclohexane), HMX (1,3, 5,7-tetranitro-1, 3, 5,7-tetraaza- cyclooctane), TEX (4, lO-dinitro-2, 6,8, 12-tetraoxa-4, lO-diaza- tetracyclo[5.5. 0. 03']dodecane), NTO (3-nitro-l,2,4-triazol- 5-one), and PETN (pentaerythritol tetranitrate).-30 - 22. -An explosive composition as defined in any one of claims ii to 71, wherein the high explosive is present in a concentration from weight percent to 30 weight percent of the explosive composition.

S

23. An explosive composition as defined in any one of clainis 11 to 22, wherein the energetic binder is present in a concentration from 15 weight percent to 30 weight percent of the explosive composition.

-31 - 24. An explosive composition comprising: an energetic binder selected from PGH (polyglycidyl nitrate), poly-NNI4O (nitratomethyl-methyloxetane), GAP (polyglycidyl azide), 9DT-NIDA (diethyleneglycol-tri- ethyleneglycol-nitraminodiacetic acid terpolymer), poly-BAMO (poly(bis(azidomethyl)oxetane)), poly-AMMO (poiy(azidcunethyl-methyloxetane)), poly-NAfl4O (poly(ni-traminomethyl-methyloxetane)), and copolyners and mixtures thereof; a reactive metal selected from aluminum, boron, magnesium, titanium, zirconium, alloys thereof, titanium hydride, zirconium hydride, and mixtures thereof; and a high explosive selected from TEX (4,10-dinitro- 2,6,8, 12-tetraoxa-4, 10-diazatetracyclo[5.5. 0. 05'9.03"Jdo- decane), NTO (3-nitro-1,2,4-triazol-5-one), NQ (nitrogna-nidine), TATE (1,3,5-triamino-2,4,6-trinitrobenzene), and TAG nitrate (triaminoguanidinium trinitrate), wherein the explosive composition has an equivalence ratio in the range from 1. 5 to 2.5.

25. An explosive composition as defined in claim 24, wherein the energtetic binder further comprises a plasticizer.-. ... -32 -a 26. An explosive composition as defined in claim 25, wherein the plasticizer is selected from BDNPF/BDNPA (bis(2,2-dinitropropyl)acetal/bis(2, 2-dinitropropyl) formal), TZ4ETN (trimethylolethanetrinitrate), TEGDN (triethyleneglycoldinj- trate), DEGDN (diethyleneglycol-dinitrate), MG (nitrogly- cerine), BTTN (butanetrioltrinitrate), alkyl NENA'S (nitrato-ethylnitrainine), and mixtures thereof.-33 -C ----Amendments to the èlaims have been filed as follows 1. An explosive composition comprising: an energetic binder; an oxidizer; a reactive metal; and a high explosive, wherein the explosive composition has an equivalence ratio in the range from 1 to 3.2. An explosive composition as defined in claim 1, wherein the explosive composition has an equivalence ratio in the range from 1.5 to 2.5.3. An explosive compe.sitiuin as defined in claim 1 or claim 2, wherein the high explosive is selected from CL-20 (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo- ROX (1,3,5-trinitro-1,3,5-triaza- cyclohexane), HMX (l,35, 7-tetranitro-1, 3' 5,7-tetraazacyclo- octane), TEX (4, 1O-dinitro-2, 6,8, 12-tetraoxa-4, lO-diazatetra- cyclo[5. 5.0. tP. 03")dodecane), NTO (3-nitro-1, 2,4-triazol-5- one), PETN (pentaerythritol tetranitrate), TATB (1,3,5-tn-amino-2,4, 6-tninitrobenzene), TNAZ (1,3, 3-trinitroazetidine), ADN (anunonium dinitramide), DADNE (l,1-diamino-2,2-dinitro ethane), and mixtures thereof.* 1;/:;-:. a4. An explosive composition as defined in any preceding claim wherein the high explosive is present in a concentration from weight percent to 50 weight percent of the explosive composition. An explosive composition as defined in claim4, wherein the high explosive is present in a concentration from weight percent tO 30 weight percent of the explosive composition.6. An explosive composition as defined in any preceding claim wherein the energetic binder is selected from PGN (polygly-cidyl nitrate), poly-NMMO (nitratomethyl-methyloxetane), GAP (polyglycidyl azide), 9DT-NIDA (diethyleneglycol-triethylene- glycol-nitraminodiacetic acid terpolymer), poly-BAMO (poly- (bis(azidomethyl) oxetane)), poly-ANMO (poly(azidomethyl- methyloxetane)), poly-NAMMO (poly(nitraminomethyl-methyl-oxetane)), and copolyniers and mixtures thereof.7. An explosive composition as defined in any preceding claim wherein the energetic binder is present in a concentration from 10 weight percent to 40 weight percent of.the explosive composition. a C;8. An explosive composition as defined in claim 7, wherein the energetic binder is present in a concentration from 15 weight percent to 30 weight percent of the explosive composition.g. An explosive composition as defined in any preceding claim wherein the energetic binder further comprises a plasticizer.10. An explosive composition as defined in claim 9, wherein the plasticizer is selected from BDNPF/BCNPA (bis(2,2-cuinitropropyl)acetalfbis(2,2-dinitropropyl)formal), TMETN (triniethylolethanetrinitrate), TEGDN (triethyleneglycoldini- trate), DEGDN (diethyleneglycol-dinitrate), NG (nitrogly- cerine), BTTN (butanetrioltrinitrate), alkyl NENA's (nitrato-ethylnitramine), and mixtures thereof.11. An explosive composition as defined in claim 9, wherein the plasticizer is selected from DOA (dioctyladipate or (2-ethylhexyl) adipate), ID? (isodecylperlargonate), DOP (dioctylphthalate), DOM (dioctylmaleate), DBP (dibutyl-phthalate), oleyl nitrile, and mixtures thereof.12. An explosive composition as defined in any preceding claim wherein the reactive metal is selected from aluminum, boron, magnesium, titanium, zirconium, mixtures, and alloys thereof. -Á t tla. Rh explosive composition as defCned in any preceding claim -wherein the reactive metal is. in the form of a metal hydride.14. An explosive composition as defined in claim 13 wherein the reactive metal is titanium hydride or zirconium hydride.15.. An explosive composition as-defined in any preceding claim wherein tLe reactive metal is present in a concentration from weight percent to 50 weight percent of the explosive composition.16. An explosive composition as defined in clam 15 wherein the reactive metal is present in a concentration from weight percent to 35 weight percent of the explosive composition.17. cAn explosive composition as defined in any preceding -claim wherein the oxidizer is selected from Al' .(aoni'int perchiorate), AN (annionium nitrate), RAN (hydroxyl-ammonium nitrate), ADN (ammonium dinitramide), and mixtures thereof -H18. An explosive composition comprising: an energetic binder selected from PGN (polyg].ycidyl nitrate), poly-NI4MO (nitratomethyl-methyloxetane), GAP (polyglycidyl azicle), 9DT-NIDA (diethyleneglycol-tri-- ethyleneglycol-nitraminodiacetic acid terpolyiner), poly-BAI4O (poly(bis(azidomethyl)oxetane)), poly-ANMO (poly (azidomethyl-methyloxetane)), poly-NANMO (poly (ni-traminomethyl-methyloxetane)), and copolymers and mixtures thereof; iO a reactive metal selected from aluminum, boron, magnesium, titanium, zirconium, alloys thereof, titanium hydride, zirconium hydride, arid mixtures thereof; and a high explosive selebted from TEX (4,10-dinitro- 2,6,8,12-tetraoxa-4, l0-diazatetracyclo(5.5.O.05'9.03"]do- decane), NTO (3-nitro-1, 2,4-triazol-5-one), NQ (nitrogua-nidine), TATS (1,3, 5'-trianiino-2,4,6-trinitrobenzene), and TAG nitrate (triaminoguanidinium trinitrate), wherein the explosive composition has an equivalence ratio in the range from 1.5 to 2.5.19. An explosive composition as defined in claim »=O, wherein the energetic binder further comprises a plasticizer.21. An explosive composition as defined in claim 20 wherein the plasticizer is selected from BDNPF/BDNPA (bis(2,2-dinitropropyl) acetal/bis (2, 2-dinitropropyl) formal), TMEPN (trimethylolethanetrjnitrate), TECDN (triethyleneglycoldini- trate), DEGDN (diethyleneglycol-dinitrate), NC (nitrogly- cerine), BTTN (butanetrioltrinitrate), alkyl NENA's (nitrato-ethylnitramine), and mixtures thereof.