Word: molybdenum
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...great that no one knew whether such an engine would work at all. The reactor must run extremely hot; otherwise the hydrogen will not form an effective gas jet. Thus Kiwi-A's innards are probably made of tricky, heat-resistant metals such as tungsten, tantalum and molybdenum. Control is far more difficult than with chemical engines, because the flow of hydrogen must be balanced perfectly against the production of energy by the reactor. A slight maladjustment of the controls might melt the nuclear engine in seconds or blow it to smithereens...
SNAP III's heart is a pinpoint one-hundredth of an ounce of radioactive polonium 210 encased in a molybdenum capsule. The polonium's entrapped radiation heats the capsule to above 700° F. Arranged around it like the spokes of a wheel are 20 thermocouples made of lead telluride. When their ends are heated by the capsule, a flow of electrons is set up in the thermocouples, producing an electric current. At peak power, SNAP III can turn out five watts. Before most of its polonium (half life: 140 days) is exhausted, SNAP III will generate...
...meet the demands of missile makers, U.S. scientists have worked for years on metals that can resist the high temperatures generated by supersonic speeds. One such metal is molybdenum, which melts at 4748° F., v. about 3000° F. in commonly used alloys. But making molybdenum castings was long impossible; its melting point is so high that it destroyed the crucible holding it. Last week the U.S. Bureau of Mines announced "a major metallurgical breakthrough"; it had succeeded in making molybdenum castings...
Metallurgists melted a 30-lb. piece of molybdenum with a high-density electric arc in a copper-lined, water-cooled crucible. The molten molybdenum was then poured through a series of troughs into a rotating graphite cylinder which forced the metal to cling to its walls while it hardened, produced a molybdenum cylinder 4½ in. wide and 8 in. long...
...development proves commercially successful, missile engineers will have greater flexibility in designing vital molybdenum parts for missiles. Molybdenum parts are now made by pressing or melting the powdered metal into ingots or billets, then forging, machining or extruding it. The new casting method may permit not only more intricate shapes but also lower costs, since the process may cut the number of steps necessary. But the major U.S. moly producer, American Metal Climax, Inc.. cautioned that it may be some time before the casting method becomes commercially feasible...