Effect of fluorine on the viscosity and structure of non-reactive mold fluxes for high-Mn high-Al steel

The impact of varying F content from 4 wt.% to 10 wt.% on the structure and properties of non-reactive mold slag for high-Mn high-Al steel was investigated in this study. Employing a combination of techniques including a rotary viscometer, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and Raman spectroscopy, the viscosity and structure of mold slag were analyzed. The findings revealed that increasing F content led to a gradual reduction in viscosity, activation energy for viscous flow, and the internal friction within the mold fluxes, consequently enhancing its fluidity. The Al-O-Al structure remained stable throughout the experimental range. The decrease in content indicated a continuous depolymerization process, leading to the formation of free Al2OF6 and AlO6 structures as F content increased. At the same time, the replaced O2- ions were assimilated by AlO4 tetrahedron, facilitating the formation AlO6 octahedron. Consequently, the slag structure was simplified, resulting in a reduction in the degree of polymerization and viscosity.