Effect of CaO/Al 2 O 3 on electrical conductivity,viscosity and structure of electroslag remelting-type TiO 2 -bearing slag

Abstract

The composition of electroslag has a great influence on the remelting behaviour, and the electrical conductivity and viscosity of slag directly affect the energy consumption and the surface quality of the alloy. The electrical conductivity and viscosity of CaF₂–CaO–Al₂O₃–SiO₂–MgO–TiO₂ slag system with different CaO/Al₂O₃ (0.9–1.8) were measured by a high-temperature physical property measuring instrument, and the structure of the slag was analysed by FTIR and Raman spectroscopy. The results showed that the electrical conductivity increased from 0.027 to 0.071 S · cm⁻¹ and viscosity decreased from 0.58 to 0.27 Pa s with the temperature rising from 1733 to 1823 K. The activation energy of each slag system increases and then decreases. The higher the temperature, the stronger the ion mobility in the melt. There is an inflection point for electrical conductivity and viscosity when the CaO/Al₂O₃ is 1.2. With the increase of Ca²⁺ and the conversion of free O²⁻, [AlO₆] and [AlF₆] to Q², Q³ and Q⁴, the decrease of melt degree of polymerisation (DOP) leads to the decrease of carrier diffusion ability. As DOP of Q², Q³ and Q⁴ continue to increase, the electrical conductivity begins to decrease and the viscosity increases. The linear equations of viscosity and electrical conductivity are established according to the experimental results.