Effect of Ce₂O₃ on the Melt Structure and Properties of CaO–Al₂O₃-based Slag

Abstract

The low-reactive tundish flux is urgently required for the smelting of rare-earth steels. The effect of Ce₂O₃ content on the properties (melting point and viscosity) and structure of CaO–Al₂O₃–Ce₂O₃–MgO–SiO₂ slag were analyzed in the present investigation. The research results indicated that the polymerized Q_Al⁴ and Q_Al³ units were modified to Q_Al² units in aluminate, and the depolymerization of SiO₄-tetrahedrons from Q_Si¹ to Q_Si⁰ units with Ce₂O₃ addition increasing from 5 wt% to 20 wt%. In addition, when the Ce₂O₃ addition increased from 15 wt% to 20 wt%, the increasing area fraction in AlO₆-octahedral units further led to a decrease in the degree of polymerization (DOP) in the melts. When the Ce₂O₃ addition increased from 5 wt% to 20 wt%, the melting temperature decreased from 1320°C to 1301°C. Additionally, the softening temperature and the fluidity temperature also decreased 20°C and 24°C, respectively. The viscosity decreased as the Ce₂O₃ addition increased from 5 wt% to 20 wt%, which was attributed to the decreased DOP and the increased superheat. A reasonable content for Ce₂O₃ should not be excess 10 wt% in the current slag.