Influence of Al2O3/SiO2 and BaO/Al2O3 Ratios on Rheological and Crystallization Behavior of CaO-BaO-Al2O3-Based Mold Slags

In this study, the rheological and crystallization behavior of CaO-BaO-Al2O3-based mold slags was investigated through the measurement of the viscosity-temperature relationship and the record of crystallization behavior during the continuous cooling process from 1 300 to 600 degrees C applying a modified confocal scanning laser microscopy. Variations of the viscosity, break temperature, initial crystallization temperature and crystallization phases of mold slags with the substitution of SiO2 by Al2O3 and Al2O3 by BaO at a gradient interval of 4 mass% were discussed, and crystallization parameters of average crystallization rate, Ozawa index and effective crystallization activation energy were calculated to explain the crystallization performance. The slag viscosity at 1 300 degrees C, the melting and break temperature increased with the substitution of SiO2 (16 to 0 mass%) by Al2O3 (20 to 36 mass%), while those decreased with the substitution of Al2O3 (32 to 16 mass%) by BaO (4 to 20 mass%). With the gradual substitution of SiO2 by Al2O3, the initial crystallization temperature increased from 820 to 1 273 degrees C at the cooling rate of 1 degrees C/s, major precipitated phases gradually changed from CaF2 to CaF2, LiAlO2 and BaAl2O4, the average crystallization rate and the Ozawa index fluctuated but had the same tendency. With Al2O3 gradually replaced by BaO, the initial crystallization temperature decreased from 970 to 775 degrees C at the cooling rate of 1 degrees C/s, major precipitated phases changed from CaF2 to CaF2 and BaAl2O4, the crystallization rate of slags was affected by the difference of the nucleation and growth rate of different crystals.

Automated summary

This study investigates the rheological and crystallization behavior of CaO-BaO-Al2O3-based mold slags, and calculates the crystallization parameters to explain the performance. The results show that the substitution of SiO2 and Al2O3, as well as Al2O3 and BaO, have an impact on the properties of the mold slags.