Crystallization characteristics of CaO–Al2O3–SiO2–Li2O–B2O3 mold flux with different values of w(CaO)/w(Al2O3)

Abstract The effect of C/A ratio (abbreviation of w(CaO)/w(Al2O3)) on the crystallization characteristics was investigated. With an increase in C/A ratio from 1.1 to 1.8, the crystallization ability first decreased and then increased; the crystallization ability is weakest and strongest with C/A ratios of 1.5 and 1.8, respectively. Increasing C/A ratio, the crystalline phase changed from LiAlO2 and CaO·Al2O3 to LiAlO2 and 3CaO·Al2O3. The Li+ ions in the slag took precedence over Ca2+ ions to participate in charge compensation because the mold flux contains Al3+ which is more advantageous for a monovalent cation, and LiAlO2 formed preferentially over CaO·Al2O3. With a further increase in C/A ratio, 3CaO·Al2O3 formed from the combination of Ca2+ ions and QAl2 units, and the precipitated amount of 3CaO·Al2O3 increased.