Ammunition and explosives – Blasting – Detonation wave modifying
Reexamination Certificate
2001-02-27
2002-09-10
Nelson, Peter A. (Department: 3641)
Ammunition and explosives
Blasting
Detonation wave modifying
C102S307000, C102S476000
Reexamination Certificate
active
06446558
ABSTRACT:
This invention relates to shaped-charge projectiles and, more particularly, to a shaped-charge liner made of fibers or particles of a reinforcement dispersed in a matrix comprising an amorphous metal.
BACKGROUND OF THE INVENTION
A shaped-charge projectile is used against armor and other hardened targets. It has an external appearance similar to a conventional round, but the internal structure is different. Behind the front end of a hollow-shell container is a metallic shaped-charge liner. Positioned further behind the metallic shaped-charge liner is an explosive charge. A detonator is in contact with the explosive charge. The projectile may also have a propulsion capability, or propulsion may be provided separately.
In operation, the shaped-charge projectile is propelled toward the target. Just prior to the projectile contacting the target, the detonator is fired to ignite the explosive charge. The force of the explosion is directed inwardly and forwardly, deforming the shaped-charge liner. The concentrated force of the explosion is so great and occurs in such a short period of time that the shaped-charge liner melts to the liquid or semi-liquid metallic state as it deforms. The resulting metallic jet of metal is forced forwardly against the target and achieves the penetration of the target. The shaped-charge liner does not penetrate the target in its solid form.
Thus, the shaped-charge projectile differs from an inert, heavy-mass penetrator in both its physical structure and its mode of operation. The heavy-mass penetrator relies upon its heavy mass and solid-state deformation behavior for its ability to penetrate the target, while the shaped-charge projectile penetrates the target in a liquefied form that is created and propelled forwardly by an explosion that occurs just as the projectile reaches its target. The physical principles that underlie the operation of conventional shaped-charge projectiles are completely different from those that underlie the operation of heavy-mass penetrators.
While operable, conventional shaped-charge projectiles have shortcomings in some applications and missions, and there is always a desire to improve an existing technology. There is therefore a need for an improved approach to the construction of shaped-charge projectiles. The present invention fulfills this need, and further provides related advantages.
SUMMARY OF THE INVENTION
The present invention provides an improved shaped-charge projectile. The present shaped-charge projectile utilizes the basic proven components of the shaped-charge projectile, but utilizes an improved shaped-charge liner material in either conventional or new physical configurations. The result is improved performance of the shaped-charge projectile.
In accordance with the invention, a shaped-charge projectile comprises a container in the form of a hollow shell elongated parallel to a projectile axis, with the container having a front end and a back end. A shaped-charge liner resides within the container adjacent to the front end of the container. The shaped-charge liner is a composite material made of a plurality of pieces of solid fibers or particles of a reinforcement dispersed in a matrix comprising an amorphous solid metal that may include some nanocrystalline metal. An explosive charge is positioned between the shaped-charge liner and the back end of the container. A detonator detonates the explosive charge, and a propulsion source may optionally be present in the projectile.
Preferably, the hollow shell is cylindrically symmetric about the projectile axis. It may have a generally conical nose, and a cylindrical rear portion continuous with the nose. The projectile may have other shapes as well, such as a flat-nosed hollow shell. The shaped-charge liner may be cylindrically symmetric about the projectile axis, or it may be asymmetric relative to the projectile axis.
The shaped-charge liner may have any operable shape, and a large number of shapes are known in the art for conventional shaped-charge projectile. In one configuration, the shaped-charge liner has the shape of a cone with a rearwardly pointing apex. In another, the shaped-charge liner is hemispherical, with its apex pointing rearwardly. (The term “shaped-charge liner” is a term of art and does not suggest that the shaped-charge liner lines the entire interior of the hollow shell of the projectile.)
The shaped-charge liner is formed of a composite material. The reinforcement phase desirably comprises from about 10 to about 95 percent by volume of the shaped-charge liner, and the balance is the matrix metal. The reinforcement is in the form of elongated fibers or more-equiaxed particles. Typical reinforcement metals include tungsten, niobium, tantalum, uranium, molybdenum, and copper, as well as alloys of each of these metals with other metals.
The matrix metal is an amorphous metal in its solid form. The matrix metal is preferably a bulk-solidifying amorphous metal which may be solidified to the desired shape of the shaped-charge liner. A preferred composition for the matrix metal, in atomic percent, is about 41 percent zirconium, about 14 percent titanium, about 12.5 percent copper, about 10 percent nickel, and about 22.5 percent beryllium.
The composite reinforcement/amorphous metal shaped-charge liner has important advantages as compared with a conventional monolithic metal shaped-charge liner or shaped-charge liner made of a composite material with a monolithic-metal matrix. The present composite reinforcement/amorphous metal shaped-charge liner does not work harden in the same manner as the conventional shaped-charge liner during the deformation period after the explosive is ignited and before the shaped-charge liner liquefies. Instead, it deforms more uniformly and nearly isotropically in compressive loading, to a large deformation strain. The result is that the shaped-charge liner achieves a large, predictable deformation prior to liquefaction.
A method for fabricating a shaped-charge projectile comprises the steps of providing a plurality of pieces of a reinforcement, providing a molten bulk-solidifying amorphous metal matrix alloy, and combining the reinforcement and the bulk-solidifying amorphous metal matrix alloy while the metal matrix alloy is molten to form a molten-matrix composite material. The reinforcement and the bulk-solidifying amorphous metal matrix alloy may be combined by any operable technique, such as infiltration, or mixing and casting. A shaped-charge liner is prepared from the molten-matrix composite material, with the step of preparing including the step of solidifying the molten matrix of the molten-matrix composite material to form a composite material of reinforcement in a solid amorphous alloy matrix. The method further includes providing other components of the shaped-charge projectile, and assembling the shaped-charge liner and the other components to form the shaped-charge projectile.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. The scope of the invention is not, however, limited to this preferred embodiment.
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Johnson William L.
Peker Atakan
Christie Parker & Hale LLP
Liquidmetal Technologies, Inc.
Nelson Peter A.
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