1991 Volume 77 Issue 4 Pages 496-503
A direct induction skull melting which was developed for melting materials with high electric conductivity at liquid state and with low one at solid state is one of skull meltings by use of high frequency induction heating. This process has the advantage of melting and holding the high melting temperature materials or chemically active ones without contamination from a crucible. It also has higher energy efficiency than that of the cold crucible which has the same advantage concerning melting without contamination from a crucible. In this melting the skull existing between coil and melt plays roles of electrical, chemical and thermal insulators so that control of the skull thickness is important. By conducting model experiments using NaCl, KCl and CaF2 as a charge, it has been found that the system stability depends on the convection which governs temperature distribution in the melt. By developing a one dimensional thermal transfer model in radial direction, the conditions for getting a stable skull have been studied and the relation between the magnetic and cooling conditions needed for the stable operation has been derived.
