Solid State Reactions in the Na2CO3, CaF2 and CaSiO3 System: The Case of a Bifurcation Point
Different studies have been conducted,beginning in 1979,on mineralogical phases which evolve in mold powders during their use in continuous casting of steel.Literature reports many studies which focus on melting,crystallization or devitrification processes and on equilibrium of mineralogical phases formed by fluxes.Most of these studies point out that,depending on different composition factors such as the basicity index,CaO/SiO2 wt%/wt%,alkali or fluorine content,these systems evolve to different silicate and fluoro-silicate phases.In many publications the most common identified phase is cuspidine,Ca4Si2O7F2,which is also an important phase in controlling thermal exchange between steel strand and mold wall.In the present work,while data available in open literature on these systems have been qualitatively confirmed,the conditions which lead,during melting process,to formation of the different crystalline fluoro-silicate phases such as cuspidine,Ca4Si2O7F2 and dicalcium sodium fluoro-silicate,Ca2SiO4.NaF,have been deeply investigated using hot stage microscope,X-ray difractometry,DSC-TGA and SEM.This study led to identification of a well-defined bifurcation point which has been found to be correlated with existence of an eutectic point in the pseudo binary system CaF2 and Na2CO3.Solid state reaction paths have been considered to explain the observed phenomena pointing out the crucial role of the liquid phase formed by this eutectic in melting process of mold fluxes and crystalline phases formation.
mold flux melting behavior cuspidine formation Na2CO3-CaF2 pseudo-binary system eutectic reaction
Marco ALLONI Riccardo CARLI
Prosimet S.p.A.,Filago(BG),Italy
国际会议
the 6th International Congress on the Science and Technology of Steelmaking,ICS2015(第六届国际炼钢科技大会)
北京
英文
626-628
2015-05-12（万方平台首次上网日期，不代表论文的发表时间）