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Abstract

The method of making the casing comprises the steps of preparing a powder mixture consisting predominantly of a metal powder mixed with a minor proportion of graphite powder ranging from about 0.2% to about 2%, preferably 0.8% by weight, while the metal powder ranges from about 99.8% to about 98% by weight. The powder material is compressed into a casing mold to a molded density ranging from about 0.21 to about 0.24, preferably 0.23 of a pound per cubic inch. The molded powder is sintered in an inert atmosphere at a temperature ranging from about 1500 to about 1700, preferably 1600.degree. F. for a time sufficient to unite the molded powder into a brittle porous frangible casing. The graphite powder vaporizes and escapes from the molded casing during the sintering step whereby porosity and frangibility are imparted to the casing. In molding the casing, a previously formed rotator band is preferably inserted into the mold so that a portion of the casing is molded within the band whereby the casing and the band are securely united. The band preferably has inwardly projecting teeth which interlock with the casing. The band is adapted to engage rifling within the barrel of the cannon. The casing is preferably formed with an axial bore wherein a hard dense penetrator rod is received, preferably made of tungsten or tungsten carbide. Behind the penetrator rod, the casing preferably has an enlarged bore wherein an incendiary pellet is received, preferably comprising zirconium crystals molded in an epoxy matrix. The casing preferably has a massive closure plug behind the incendiary pellet.

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First Claim