The subject is an unconventional method of heating and melting metals without a crucible, by suspension in space with an electromagnetic field. Operating conditions for certain cases are given. The results obtained by means of the new technique encourage the thought of melting, purifying, alloying, and agitating of inert and reactive metals without resort to crucibles, and thereby avoiding the contamination of reactive metals by crucible materials. Preliminary results with various forms and masses of metal are described. Considerations concerning the atmosphere in which levitation occurs are included.
An original method of heating and melting metals without a crucible, by suspension in space with an electromagnetic field, is described. The required field was generated by applying high frequency alternating current to two coaxial coils connected in series opposition. Stable levitation and heating of various metals in the solid state was obtained between the coils in the vicinity of the common axis, both in air and in a vacuum. Weights levitated ranged up to 550 grams. In air, some tens of grams of Al, Sn, and a brass were brought to melting and continued in levitation while in the liquid state. In a vacuum, 10 grams of Al was successfully levitated molten. On the other hand, several attempts to levitate molten Ag, Ti, and Zr in a vacuum failed.
Two methods for the determination of oxygen are reviewed and applied to the analysis of zirconium. The first is indirect and involves combustion of the metal and calculation of the oxygen content by difference. Corrections must be nmde for hafnium and other oxygen absorbing, inert, or volatile contamin,mts and the method is, therefore, useful only for contr()l purposes or where relatively large amounls of oxygen are present.The second procedure is a direct determination of the zirconium oxide content by w~porization ()f the met'd in chlorine gas. The micro-structures of heat; treated zirconium wires with and without added oxygen are shown. They indicate why, in some cases, hardness increased with heating alone. Microhardness measurements on a series of oxygen-doped wires have provided a correlation between oxygen content and hardness. The hardness of zirconium increases roughly 50 V.P.N. for each 0.1 per cent of added oxygen and metal containing more than about 0.2 per cent oxygen is probably not cold workable.
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