Melting and Casting of Lightweight Ceramic Armor.
Final rept. 1 Jul 69-31 Mar 70,
BATTELLE MEMORIAL INST COLUMBUS OH
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The arc-melting process was investigated as a method of fabricating boron carbide-base materials for armor applications. Small-scale studies on castings measuring 12 in. in diameter by 2 in. long led to the selection of the B4C-SiC eutectic composition for full-size skull casting studies to yield tiles for ballistic tests. Procedures were developed for producing castings measuring about 6-12 in. wide by 1-14 in. thick by 9 in. high, including a 2-12 in. hot top, for the ternary alloy boron-25 wo silicon-22 wo carbon. This composition results in a largely eutectic structure of B4C-SiC and about 5 wo silicon. An off-eutectic composition was found desirable in order to insure an absence of primary graphite which can lead to tap hole constriction which makes pouring difficult or impossible, cold shuts, and also can cause microcracking in castings that are produced. The same benefits would be derived from an all eutectic composition, but closer compositional control is necessary in this case. Eleven castings of this composition were prepared. These castings were characterized by macro cracks, a centrally located zone of porosity parallel to the large faces of the castings, and excessive shrinkage in the thickness direction, making it impossible to obtain sound test pieces measuring 6 by 6 by 38 in. Measures for minimizing cracks and pores were developed near the end of the program. Author
- Ceramics, Refractories and Glass