The effect of boron oxide on the crystallization behavior of MgAl2O4 spinel phase during the cooling of the CaO-SiO2-10 mass.% MgO-30 mass.%Al2O3 systems

• Published in: Metals and materials international Vol. 16; no. 6; pp. 987 - 992
• Main Author: Park, Joo Hyun
• Format: Journal Article
• Language: English
• Published: Springer The Korean Institute of Metals and Materials 01.12.2010; 대한금속·재료학회
• Subjects: Aluminosilicates; Characterization and Evaluation of Materials; Chemistry and Materials Science; Engineering Thermodynamics; Heat and Mass Transfer; Machines; Magnetic Materials; Magnetism; Manufacturing; Materials Science; Metallic Materials; Processes; Solid Mechanics; 재료공학; crystallization; spinel inclusion; thermodynamic properties; oxides; solidification
• ISSN: 1598-9623; 2005-4149
• DOI: 10.1007/s12540-010-1220-3

The microstructural characteristics of the CaO-SiO 2 -B 2 O 3 -10 mass.% MgO-30 mass.% Al 2 O 3 systems solidified during slow cooling from 1600 °C were investigated using SEM-EDS and a thermochemical computation package. The effect of boron oxide on the crystallization behavior of the spinel in the aluminosilicate system was observed because boron oxide is believed to become a potential flux to reduce the melting point of the liquid oxides. The primary crystalline phase was spinel, mainly MgAl 2 O 4 , irrespective of the boron content. The liquidus temperature T L continuously decreased as the boron oxide content increased, indicating that the boron oxide decreased the activity of the MgAl 2 O 4 spinel phase in liquid melts at high temperatures. The size of the spinel crystals increased as the temperature range for the solid + liquid coexisting region, viz . the mushy zone, increased. In the present systems, because the T L continuously decreased with the increase in the boron oxide content, the viscosity of the liquid oxide may have affected the crystallization behavior of the spinel during cooling. Based on these results, an injection of a small amount of B 2 O 3 flux into molten steel containing liquid aluminosilicate inclusions is not recommended because large spinel crystals can originate from the changes in the thermophysical properties of the liquid inclusions due to the incorporation of boron oxide into the aluminosilicate networks.