US2918362A - Explosive composition - Google Patents

Description

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2,918,362 Patented Dec. 2 2, i959 EXPLOSIV E COMPOSITION Duncan P. MacDougall, Pittsburgh, Pa., Paul M. ljye,

Woods Hole, Mass., and George B. Kistiakowsky, Pittsburgh, Pa., assignors to the United States of America as represented by the Secretary of the Navy No Drawing. Application June 24, 1944' Serial No. 542,008 a 1 Claim. c1. 52-6) This invention relates to explosives and has particular relation to an explosive composition of high density for use in ordnance devices, such as depth charges, mines, and the like, where high density is one of the desired characteristics of the explosive.

An object of this invention is to provide an explosive composition which will have a high density, an increased damage range as compared to known explosives such as trinitrotoluene, and good casting properties.

Another object of the invention is to provide an explosive composition which will have desirable thermostability and an impact sensitivity in the neighborhood of that possessed by trinitrotoluene.

A further object of the invention is to provide an explosive composition which will be fluid enough to be readily poured at temperatures of about 80 to 90 C. but will not be so fluid as to cause serious segregation of the components.

Still another object of the invention is to provide an explosive composition which will solidify on cooling to give a solid having a consistent density throughout its mass.

A still further object of the invention is to provide an explosive composition which is capable of being safely and efliciently melted, cast and subsequently handled by methods now used for trinitrotoluene and other known explosives.

A still further object of the invention is to provide an explosive composition which may be safely and efficiently used in place of trinitrotoluene and other known military explosives in ordnance equipment, such as depth charges, mines, and the like.

An additional object of the invention is to provide an explosive composition which may be subjected to existing military and naval practices for handling and firing explosives.

These and other objects of the invention will be better understood by reference to the accompanying description.

The invention broadly comprises an explosive composition of trinitrotoluene, barium nitrate and aluminum powder. 'In a preferred form, the new explosive composition comprises a composition of 35 percent trinitrotoluene, 50 percent barium nitrate and 15 percent aluminum pow- It will be understood that other substantial percentages of these ingredients may be employed. For example, the composition may include from 15 to 50 percent tn'nitrotoluene, 30 to 60 percent barium nitrate and about 10 to 25 percent aluminum powder.

An explosive having a high density is particularly desirable for use in underwater ordnance devices, such as depth charges, mines, and the like, where the function of the ordnance is partially dependent upon its degree of buoyancy. For example, the rate of sinking of a depth charge is primarily dependent upon its density. Although the weight of the ordnance devices may be increased by the addition of heavy weights, such addition lessens the volume of space which may be allotted to the explosives. Accordingly,,it is desirable that an explosive composition be utilized which will contribute to the weight, and therefore the density, of the ordnance equipment for underwater use.

Example 1 A technical grade barium nitrate powder was selected having an approximate screen analysis as follows: 53 percent through a 325 mesh screen; 20 percent through a 200 mesh screen onto a 325 mesh screen; 11 percent through a 150 mesh screen onto a 200 mesh screen; 7 percent through a mesh screen onto a 150 mesh screen; and 9 percent through a screen-slightly coarser than 100 mesh. An atomized aluminum powder was selected, approximately 95 percent of which was capable of being passed through a 200 mesh screen. The particular aluminum powder used in this exmaple was commercial grade MD 101. An ordinary military grade of granular trinitrotoluene was used. These ingredients were compounded into a composition comprising 35 percent trinitrotoluene, 50 percent barium nitrate, and 15 percent of the aluminum powder. It has been found that this preferred percentage composition results in an explosive composition having desirable characteristics including high density, increased damage range and good casting properties.

The new explosive composition was tested for thermostability by heating 10 to 20 gram samples up to 200 C. for 20 minute periods. These samples failed to ignite nor was there any visible evidence of decomposition. Further samples were held for a period of two hours at temperatures between 150 C. and 200 C. without any indication of decomposition having taken place. Other samples exposed to the standard C. thermostability test for a period of five hours showed no acidity, explosion or other evidence of decomposition. Other samples exposed to the vacuum stability test showed results approximately the same as those obtained with trinitrotoluene, while still other samples of the new explosive composition were subjected to the standard Woods-metal bath explosion test and gave no indication of exploding at 360 C.

It is difiicult to compare the sensitivity of a mechanical explosive composition with that of a pure explosive material. However, when the new explosive composition was subjected to tests on standard impact machines, the tests indicated an impact sensitivity not appreciably greater than that exhibited by trinitrotoluene. When exposed to the standard rifle bullet test, the new explosive composition gave some evidence of partial detonation when cast in either a welded steel case or in standard plumbing pipe nipples.

The new explosive composition solidified on cooling from the molten state to give a slightly porous, rock-like material having a density of about 2.3 grams per ml. A cast charge of the new explosive composition was separated into various small sections which were measured for density. It was observed that there was no marked variation in density between the small sections, which indicated that very little settling took place either prior to or during solidification of the cast charge.

The physical characteristics of the new explosive composition are such that it may be readily substituted for present explosives now used in underwater ordnance equipment. Thus, the new explosive composition may be subjected to present loading conditions and practices, it may be shipped and stored by present practices, and it may be detonated by means of detonators now in use. In this connection, it 'has been found that the new explosive composition is fiuid enough to be readily poured when heated at temperatures from 80 to 90 C., but

it is not so fluid as to cause serious segregation between the components of the composition.

We claim:

A cast explosive composition for underwater ordnance characterized by a density of substantially 2.3 and consisting essentially of the following, by weight: 35 percent trinitrotoluene, 50 percent barium nitrate powder of 5 3 percent 325 mesh screen particle size, 20 percent 200 mesh screen particle size, 11 percent 150 mesh screen particle size, 7 percent 100 mesh screen particle size and 9 percent of particle size coarser than 100 mesh screen; and 15 percent atomized aluminum powder, approximately 95 percent of which is of particle size finer than 200 mesh screen.

References Cited in the file of this patent UNITED STATES PATENTS