Effect of F − Replacing O 2 − on crystallization behavior of CaO–SiO 2 –Al 2 O 3 continuous casting mold flux

Abstract

In the molten slag system of CaO–SiO 2 –Al 2 O 3 , F − will replace part of the bridging oxygen in the Al–O network as bridging fluorine. The electronegativity of fluoride ions is greater than that of oxygen ions. By maintaining the molar number of metal cations, and using an equimolar amount of CaF 2 to replace CaO, i.e., F − instead of O 2− , the main focus of this research is whether one can inhibit the crystallization of the CaO–SiO 2 –Al 2 O 3 slag system. In this paper, the techniques of single hot thermocouple technique, X-ray diffraction and Raman spectroscopy were used to analyze the crystalline properties, the crystalline phases and the molten slag structure. The results show that with the increase in the amount of equimolar CaF 2 replacing CaO, the structure of Q 0 decreases in prevalence, the structure of Q 2 , Al–F–Al and Al–O–Si with high polymerization increases in prevalence, the critical cooling rate decreases, the high temperature precipitation material of the sample changes from dicalcium silicate to gehlenite, and there will be CaF 2 precipitation at low temperature.