Crystallization Kinetics of Mold Slag Containing CeO₂ in Isothermal and Non-isothermal Process

Abstract

In rare-earth steel continuous casting, researchers examined the role of cerium oxide (CeO2) in mold slag crystallization. Using single hot thermocouple technique (SHTT) and Raman spectroscopy, they investigated the CaO-SiO2-Al2O3-Na2O-CaF2-(CeO2) slag system. The CeO2 was found to reduce structural polymerization, increase substance migration rates, and promote slag crystallization. Applying Johnson-Mehl-Avrami (JMA) and modified JMA models revealed distinct crystallization behaviors. In isothermal conditions, the crystal growth mechanism transitioned from one-dimensional to three-dimensional as temperature increased. Non-isothermal analysis consistently showed three-dimensional crystal growth. The models quantified how CeO2 content influences crystallization kinetics, demonstrating altered growth patterns. As CeO2 increased to 3%, the isothermal crystallization activation energy rose from 153.59 to 302.58 kJ/mol, indicating enhanced crystallization drive. Under non-isothermal conditions, with cooling rates of 1 to 20 °C/s, the apparent activation energy ranged from -288.44 to -941.97 kJ/mol. The negative values suggest that accelerated cooling and increased CeO2 concentration reduce crystallization process inhibition.