Effect of Lithium Oxide an‎d Boron Oxide on Reducing Fluorine Consumption an‎d Phase Transformation in Continuous Molding Powders Based on CaO-SiO2

10/22/2026 12:00:00 AM

Mold powder is a key component in the continuous steel casting process, whose main function is to control heat transfer between molten steel an‎d copper mold, lubricate the initial shell, an‎d absorb impurities. The chemical composition of this powder plays a decisive role in the thermal behavior, viscosity, melting temperature, an‎d final quality of steel. Among the components, calcium fluoride (CaF₂) is usually used as the main lubricant; however, its adverse environmental effects an‎d tendency to nozzle erosion (SEN) have led to the investigation of suitable alternatives. In this study, the effect of gradual addition of boron oxide (B₂O₃) an‎d lithium oxide (Li₂O) as partial an‎d simultaneous substitutes for CaF₂ on the thermal an‎d rheological properties of mold powder was investigated. For this purpose, seven mold powder samples were designed an‎d prepared, an‎d sample MF8 with 8 wt% CaF₂ was selec‎ted as the reference sample. Three samples including MBF5, MBF4 an‎d MBF3 with 2.3, 2.4 an‎d 2.5 wt% of boron oxide respectively an‎d three other samples with simultaneous combination of boron oxide an‎d lithium including ML2F4, ML4F4 an‎d ML6F4 with 2, 4 an‎d 6 wt% of lithium oxide respectively were prepared an‎d studied. The samples were subjected to X-ray diffraction (XRD) tests to identify crystalline phases, differential thermal analysis (DTA) to determine crystallization, melting an‎d fracture temperatures, an‎d scanning electron microscopy (SEM) to examine the microstructure. Also, in order to determine the fluidity behavior an‎d viscosity changes, a slot viscometer was used at different temperatures. The results showed that with increasing boron oxide content, the melting temperature an‎d crystallization temperature decreased an‎d the formation of gelnite (Ca₂Al₂SiO₇) an‎d wollastonite (CaSiO₃) phases was facilitated. In samples containing lithium, the fracture temperature an‎d viscosity were reduced an‎d the melt fluidity was improved. Also, the presence of B₂O₃, by creating a more stable glass structure, facilitated crystallization an‎d reduced the activation energy of the melting process. Overall, the results of this study show that the controlled replacement of CaF₂ with a combination of B₂O₃ an‎d Li₂O can, while maintaining the fluidity performance, reduce the melting temperature, facilitate the crystallization process, an‎d provide better control over heat transfer an‎d mold powder viscosity in the continuous casting process.

پودر قالب , ريخته گري پيوسته , ويسكوزيته , اكسيد بور , اكسيد ليتيم , دماي شكست

Mold powder , continuous casting , viscosity , , boron oxide , lithium oxide , fracture temperature

jalil sadpour hadam

rahim naghizadeh & hamidreza rezai