Explosive and thermic compositions or charges – Containing hydrazine or hydrazine derivative
Reexamination Certificate
2000-04-28
2002-03-19
Miller, Edward A. (Department: 3641)
Explosive and thermic compositions or charges
Containing hydrazine or hydrazine derivative
C149S018000, C149S019100, C149S105000
Reexamination Certificate
active
06358339
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to derivatives of 3,4-diaminofurazan useful as insensitive high explosive materials.
BACKGROUND OF THE INVENTION
The synthesis of 3,4-diaminofurazan was first reported by Coburn in J. Heterocyclic Chem., vol. 5, pp. 83-87 (1968). Since then a large body of work has been accumulated on the oxidation of 3,4-diaminofurazan, especially by Russian scientists, e.g., Solodyuk et al., in Zh. Org. Khim., vol. 17(4), pp. 756-759 (1981) wherein the compounds 3,3′-diamino-4,4′-azoxyfurazan (DAAF) and 3,3′-diamino-4,4′-azofurazan (DAAzF) were described. They used a variety of peroxide reagents on 3,4-diaminofurazan to prepare 3,3′-diamino-4,4′-azoxyfurazan (DAAF), 3,3′-diamino-4,4′-azofurazan (DAAzF) and 3-amino-4-nitrofurazan usually as mixtures which were separated by differing solubilities. However, no characterization of the explosive properties of these compounds was reported.
One previously known explosive formulation included a combination of 2,2′,4,4′,6,6′-hexanitrostilbene (HNS) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). While this formulation has been useful, it suffers some drawbacks in terms of performance and safety. Improved formulations including TATB have been sought.
The present inventors undertook a study of the compounds 3,3′-diamino-4,4′-azoxyfurazan (DAAF) and 3,3′-diamino-4,4′-azofurazan (DAAzF). Through their efforts, it was found that the compounds 3,3′-diamino-4,4′-azoxyfurazan (DAAF) and 3,3′-diamino-4,4′-azofurazan (DAAzF) were both useful as insensitive high explosive materials. In addition, an improved synthesis of 3,3′-diamino-4,4′-azofurazan (DAAzF) was developed. Also, formulations of 3,3′-diamino-4,4′-azofurazan (DAAzF) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) should overcome the drawbacks of TATB/HNS formulations.
It is an object of this invention to provide an improved process for preparation of 3,3′-diamino-4,4′-azofurazan (DAAzF).
Another object of the present invention is to provide for use of 3,3′-diamino-4,4′-azoxyfurazan (DAAF) and 3,3′-diamino-4,4′-azofurazan (DAAzF) as insensitive high explosive materials.
Still another object of the present invention is to provide formulations including 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) and 3,3′-diamino-4,4′-azofurazan (DAAzF).
SUMMARY OF THE INVENTION
To achieve the foregoing and other objects, and in accordance with the purposes of the present invention, as embodied and broadly described herein, the present invention provides for the use of 3,3′-diamino-4,4′-azoxyfurazan (DAAF) and 3,3′-diamino-4,4′-azofurazan (DAAzF) as insensitive, high explosive materials.
The present invention further provides a process for the preparation of 3,3′-diamino-4,4′-azofurazan (DAAzF) from 3,4-diaminofurazan.
The present invention further provides a composition including 3,3′-diamino-4,4′-azofurazan and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB).
DETAILED DESCRIPTION
The present invention is concerned with insensitive, high explosive materials. The particular insensitive, high explosive materials of the present invention include 3,3′-diamino-4,4′-azoxyfurazan (DAAF) and 3,3′-diamino-4,4′-azofurazan (DAAzF). Neither compound has previously been known as insensitive, high explosive material.
In addition to the use of these particular compounds as insensitive, high explosive materials, the present invention is concerned with compositions including 3,3′-diamino-4,4′-azofurazan and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB).
By the term “insensitive”, it is generally meant that the material has a drop height of greater than 320 cm as measured by using a 2.5 kg falling weight (Type 12).
Both 3,3′-diamino-4,4′-azoxyfurazan (DAAF) and 3,3′-diamino-4,4′-azofurazan (DAAzF) derive a significant amount of their energy of detonation from their intrinsically high heats of formation (&Dgr;H
f
) and not from oxidation of carbon in the backbone. This, in a large part, is due to the presence of the azo- and azoxy-linkage. As an example of this, 3,3′-diamino-4,4′-azofurazan only has enough available oxygen to burn its hydrogen to water and none to oxidize carbon, yet it has better explosive performance than HNS (2,2′,4,4′6,6′-hexanitrostilbene) which is able to burn 64% of its carbon to CO. In addition, the impact sensitivity of 3,3′-diamino-4,4′-azofurazan was determined to be greater than 320 cm while the drop height of HNS was published (Dobratz, “Lawrence Livermore National Laboratory Explosives Handbook. Properties of Chemical Explosives and Explosives Simulants”, National Technical Information Service, UCRL-52997, 1981) to be 54 cm (2.5 kg, Type 12).
Pure 3,3′-diamino-4,4′-azoxyfurazan (DAAF) is an orange-yellow crystalline powder having a DSC onset of 248° C. and an x-ray crystal density of 1.747 g/cm
3
. DAAF was found to have a drop height of greater than 320 cm (2.5 Kg, Type 12) and elicited no response to spark (>0.36 J) or friction (>36 kg, BAM). DAAF had a measured &Dgr;H
f
=+106 kcal/mole. Low density pellets of DAAF could be pressed neat but high density pellets tended to wafer and therefore required formulation with 5 volume percent of latex Kel-F 800 resin (a chlorotrifluoroethylene/vinylidene fluoride copolymer, available from 3M Company). This allowed pressing of pieces up to a density of 1.70 g/cm
3
(97% of theoretical maximum density). A Henkin critical temperature was determined to be 241° C. for the Kel-F formulated material and 252° C. for the neat material.
The explosive performance properties of DAAF were examined. A poly-&rgr; test, which determines detonation velocity as a function of density, was performed at two diameters, 0.5 in. and 0.25 in. These two diameters revealed that the detonation velocity was relatively independent of diameter. The detonation velocity of DAF was determined to be 8.0 kilometers per second (km/s) at a density of 1.69 g/cm
3
. This data was further verified by an unconfined rate stick of pellets at a density of 1.69 g/cm
3
and 3 mm in diameter. As evidenced by the witness plate a complete detonation was achieved. Unfortunately, this test was too small to be instrumented accurately to determine detonation velocity. A failure diameter of less than 3 millimeters (mm) is unprecedented in a material which is insensitive to impact. The detonation pressure (P
CJ
) was estimated to be 299 kbar from a 0.5-inch diameter plate dent at a density of 1.69 g/cm
3
.
Shock sensitivity was characterized by performing six wedge tests, in which the DAAF was plastic-bonded with 5% Kel-F 800 resin and pressed to 1.705 g/cm
3
. There have been many variations on the wedge test; the present one is the so-called “mini-wedge” test (see Seitz, Shock Waves in Condensed Matter, 531 (1983) and Hill et al., Shock Compression of Condensed Matter, 803 (1995)) which is designed to use a minimal amount (about 7 g) of sample explosive. Material conservation is desirable for screening new explosives, due to cost.
From the wedge testing, it was found that DAAF was quite like HMX so far as shock sensitivity was concerned.
The explosive energy was characterized by performing a standard 1-inch cylinder test on DAAF neat-pressed to 1.691 g/cm
3
. The cylinder energy was determined to be 1.22 kilojoules per gram (kJ/g) for DAAF. The test consists of a 1.00-inch inner diameter, 0.10-inch wall copper tube filled with explosive and detonated at one end. The pressure of the explosive products expands the tube in a funnel shape. With proper care the tube will typically expand to about three times its initial diameter before it begins to fragment. To achieve this much expansion requires very tight mechanical tolerances and high standards of purity, temper, and grain size for the copper. These requiremen
Bishop Robert L.
Chavez David E.
Hiskey Michael A.
Kinkead Scott A.
Kramer John F.
Cottrell Bruce H.
Miller Edward A.
The Regents of the University of California
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