Effect of MgO on Crystallization and Heat Transfer of Fluoride-Free Mold Fluxes

The effect of MgO on crystallization and heat transfer of fluoride-free mold fluxes was studied using single/double-hot thermocouple technique (SHTT/DHTT) and infrared emitter technique (IET), respectively. SHTT experiments demonstrated that the increase of MgO concentration promoted the crystallization tendency of mold fluxes. XRD analysis showed that the dominant phases changed from CaSiO3 to CaSiO3/Ca2MgSi2O7/Ca11Si4B2O22, and to Ca2MgSi2O7 as the MgO content was increased. The heat flux across mold flux disks was reduced from 671 to 615 kW/m2 in IET experiments when MgO concentration was increased from 0.9 to 4.9 mass pct.