Effect Of Fluoric Material Kind On Crystallization And Heat Transfer Of Mold Fluxes

In the production process of continuous casting,crystallizer protecting slag plays avery important role, especially in the control of slab crystallizer direction to heattransfer and lubricating casting blanks. Improve crystallization properties of mold fluxfor reducing slag film thermal conductivity, thereby reducing between mold and strandtransfer, which is the present domestic and foreign control crack sensitivity steel slabsurface crack of commonly used methods, but with the crystallization rate increased,prone to deterioration of billet lubrication condition. Therefore, the protecting slagcrystallization properties of regulation is the key.F-as the protective slag of flux, its rawmaterials type selection for production practice play a very important influence, and theraw materials of different types because of its various components formed by thereaction of different minerals, the cooling process of separated crystal ore is complex,the performance of protecting slag to produce different effects, therefore protective slag,type choice is particularly important.This paper focuses on the research of protectiveslag added fluoride raw material type on the crystallization and heat transferperformance, in order to protect the residue of raw materials selection and bycontrolling the raw material type to control flux heat transfer and provide a theoreticalbasis for lubrication performance.This topic is in the National Natural Science Foundation support, through the hotwire method （Single Hot Thermocouple Technique, referred to as SHTT）, heat fluxsimulation instrument, scanning electron microscope and rotational viscometer,determination of crystallizer protection slag viscosity, melting and crystalline phase,research on NaF, CaF₂of two fluoride materials in different basicity and the same F-ion content, for protection slag crystallization and heat transfer performance.Theexperimental results show that:①Two groups of slag melting temperature withincreasing alkalinity decreased gradually, and the group NaF slag on protecting slagmelting temperature regulating ability than group CaF₂slag basicity, less than1.2,group CaF₂slag melting point average than group NaF slag high12.9℃;②Thealkalinity, low basicity, CaF₂with NaF more effectively reduces the viscosity of theprotective slag, slag and group CaF₂than group NaF slag viscosity average small0.019Pa? S, high alkalinity, two fluoride materials on protecting group slag viscosityreducing effect difference;③G roup CaF₂slag reduction slag incubation time effect is more significant than that of NaF, CaF₂and NaF can promote the crystallization;④Twogroups of slag basicity of slag film thickness increases were gradually reduced, in lowbasicity, both on the flux film thickness at the same rate, in, high alkalinity, NaF groupthan that in CaF₂group decreased slag slag slag film thickness ability, and group CaF₂than in group NaF slag slag slag film the average thickness of0.198mm;⑤Two groupsof slag basicity increases with the crystallization rate gradually increased, group CaF₂slag crystallization rate greater than NaF group of slag, the difference between the twois about0.0959;⑥Two groups of slag average heat flux density and characteristics ofthe average heat flux density with the basicity was an increasing trend, and the verysimilar, the alkalinity is1.05, the average heat flux density value for0.063MW/m2.