Experimental investigation of induction melting in cold crucible for high temperature processing of oxides using HF transistor power supply

The subject of the presented work is the experimental investigation of induction melting of electrically low conductive materials in cold crucible (IMCC) using high-frequency transistor power supply. Significantly lower frequency and voltage as well as different output character- istics of transistor converters require extending experimental experience for IMCC technology based on using vacuum-tube generators. IMCC is a unique process based on contactless transfer of energy to the melted material by high frequency electromagnetic field of high intensity. In spite of conventional induction melting technologies, IMCC is oriented to melt materials with low electrically conductivity in solid phase. Extremely high chemical purity of IMCC process at very high temperature is reached because of no contact of the melt to the crucible. The design of IMCC with the cold crucible separated from the induction coil makes the process very robust and applicable for aggressive chemical compositions and most heavy process conditions. One real scale experimental installation for investigation of various IMCC processes and systems has been designed and built at the Institute of Electrotechnology of the Leibniz Uni- versity of Hannover. The structure of the installation and a detailed description of its parts are presented in the work together with numerous methodologies of experimental investigation. Melting of glasses and oxides in cold crucible for various scientific and industrial applications has been analysed experimentally. The universal design of the installation with transistor power supply has allowed carrying out a comprehensive research for single-crystal growing, glass melting, high temperature liquid phase synthesis and investigation of phase diagrams using IMCC process at frequency range of 80-300 kHz. The received results and experimental experience can be effectively used for development and design of high power IMCC installations for single-crystal growing, creating and inves- tigating new oxide-based material as well as for high temperature synthesis of glasses or for vitrification of radioactive waste. keywords: induction melting in cold crucible, experimental investigation, transistor power supply, melting of glasses and oxides.