Electrical Conductivity of Molten Slags for Electro-slag Remelting

Abstract

A four electrodes method with alternative current has been developed for measurement on the electrical conductivity of ionic melts at high temperatures, especially for that of CaF₂-based slags for electro-slag remelting (ESR). The electrical conductivity was measured systematically for CaF₂-based slags containing MgF₂, BaF₂, CaO, BaO, Al₂O₃, TiO₂, ZrO₂, and CaS. From the results, the conduction mechanism of those slags was discussed in terms of molar conductivity.
The molar conductivity of CaF₂ melt was changed with the addition of alkaline-earth oxides and fluorides, such as MgO, CaO, BaO, MgF₂, and BaF₂ in accordance with the intensity of cation-anion attraction. It suggests that those additives have a tendency to behave as ionic pairs in the melt. The remarkable decrease on the electrical conductivity of the melts was observed by the addition of some oxides, such as Al₂O₃, TiO₂, SiO₂, and ZrO₂ into the melts. It suggests that those additives have a tendency to form oxyfluoride complex ions. An empirical equation was proposed for the calculation of the conductivity of multi-component slags for the ESR process.