Effect of TiO 2 on melting and crystallisation properties of CaF 2 (50%)-CaO-Al 2 O 3 -MgO(3%)-ZrO 2 (4%) electroslag

Abstract

This study investigates the effect of highly fluorinated electroslag with TiO₂ content of 0%, 3%, 6% and 9% on the melting process, crystallisation kinetics and crystalline product structure by using STA, XRD and SEM-EDS techniques. The results demonstrated a gradual decrease in the melting temperature, heat of fusion and first crystallisation temperature of the slag as the TiO₂ content increased. The main precipitation phases in the slag are Ca₁₂Al₁₄O₃₂F₂, CaF₂, CaZrO₃, CaTiO₃, (Ca, Zr, Ti)O₂ and MgO. The larger the ratio of TiO₂:ZrO₂, the higher the precipitation rate of multi-faceted CaTiO₃. The precipitation of dendritic CaZrO₃ was also gradually suppressed. Crystallisation kinetic analysis revealed that the slag exhibited the highest activation energy for crystallisation at a TiO₂ content of 6%. These findings have a positive impact on determining the TiO₂ content in the electroslag and enhancing the surface quality of the ingot.