Abstract
A direct induction skull melting process, in wihch a water-cooled induction coil is directly used as a crucible, enjoys an advantage of non-contamination from the crucible together with high energy efficiency. The applications of this process, however, are limited to the materials with electrical insulating property in solid state. The aim of this study is to extend the applicable materials of the process and to melt and hold the materials with electrical conducting property in solid state such as metals and semiconductors by coating a insulating film on the coil surface. In order to clarify a theoretical base of the process, electric and magnetic fields and a temperature one are simultaneously analyzed by taking account of the differences of electrical and thermal conductivities in solid and liquid states. Experiments demonstrate the feasibility of the process for a stainless steel and a silicon which indicate the electrical conducting property in solid state and clarify the validity of the theoretical results. It is found that the conditions of the smaller thermal conductivity, the higher heat transfer coefficient and the lower magnetic frequency, can provide the wider range of the magnetic field to form the stable skull.
