Design of a cold crucible and characteristics of melting and levitating on materials with a high temperature melting

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1. To evaluate the effects of design parameters of a cold Crucible, a three-dimensional mathematical model was developed where the boundary element method was employed to solve the magnetic field distribution around a cold crucible system. The fundamental information for design was obtained by use of the model.2. The new hybrid process which combines a cold crucible and a plasma was proposed. This process can melt materials such as oxide, carbide and nitride, an electric conductivity of which is relatively low in solid state but increase drastically at the melting point. Furthermore, it was found that the process was useful for melting materials with high melting point such as WC, Mo, and Nb. The relations between operating conditions of the process and physical properties were clarified by use of mathematical model developed for the process and by the experimental results.3. Another hybrid process which combines the SHS(Self-propagating heatfront synthesis)reaction and the cold crucible are developed. By use of the process, TiAl intermetallic compound which is promising to use as the high temperature resistance materials in the future generation, could be successfully melted. The process has advantages to suppress Al vaporization by controlling the atmosphere pressure, to allow the precise control of compositions due to electromagnetic mixing and to decrease the oxygen content due to high vaporization rate of suboxides.4. By developing a mathematical model of SHS reaction, the condition for which the heat wave can propagate in the steady state was derived.5. A new type of the cold crucible was designed for concentrating magnetic field and its applicability to the zone melting process was studied by the ways of the theoretical analysis and the experiments.