The Research On Influence Mechanism Of MgO In Continuous Casting Mold Fluxes

Continuous casting mold fluxes have many important metallurgical functions,especially for the lubrication of billets and the heat transfer of the casting billet to mold,which is important to maintain the continuous casting process and improve the surface quality of the billets.With the continuous expansion of continuous cast steel varieties and continuous casting quality requirements,the physical and chemical properties of continuous casting slag,the continuous casting process and the quality of casting billet are increasingly prominent,becoming limiting factors in the development of continuous casting technology.MgO is a kind of flux which is commonly used in continuous casting mold,which can reduce melting temperature,improve rheological property of slag and inhibit crystallization of slag.However,there is still a lack of systematic research on the mechanism of MgO in different slag systems,and the effect of MgO on slag structure is still not enough.Based on the study of the influence of MgO content on macroscopic physical energy?constant temperature viscosity,temperature viscosity,critical cooling rate,slag film thickness,heat flux density?under the condition of CaO-SiO₂ and CaO-SiO₂-Al₂O₃under certain alkalinity,this paper The relationship between the variation of MgO content and microstructure of molten slag was analyzed qualitatively and quantitatively by Raman spectroscopy.In order to analyze the effect of MgO content on its macroscopic physical energy through the influence of MgO content change on the microstructure of molten slag,the research will play a guiding role in the rational application of MgO in the slag.The study of CaO-SiO₂ slag system shows that MgO mainly plays the role of network destroy in slag structure,when mgo<12mol%,MgO is only a small amount of ionization,when MgO content reaches 15mol%,while MgO begins to have a large amount of ionization,but its ionization product mg²⁺charge compensation effect promotes the[AlO₄]The formation of tetrahedron structures.With the increase of MgO content in slag,the polymerization degree of the system showed a slow decreasing trend.As a result,the viscosity of slag decreases slowly,the thermal stability and crystallization performance increase gradually,the maximum heat flux density decreases,and the average heat flux density increases.The study of low bascity CaO-SiO₂-Al₂O₃ system shows that when MgO<12mol%,the high content of Al₂O₃ will promote the ionization of MgO,the ionization products of MgO,O^2-play the role of net breaker,the system polymerization degree is reduced significantly,when MgO content is increased to 15mol%,Under the influence of MgO,there are a large number of vial in the system,the formation of vial will make[Si-O]structure of high-frequency Raman Peaks Blue Shift,and the role of Vial Bridge leading to a large number of large anions in the structure,will increase the complexity of slag structure,so that the slag system polymerization degree.Thus,with the increase of MgO content,the viscosity first decreased and then increased,the thermal stability was not significantly reduced after first,the crystallization performance increased and then decreased,the maximum heat flux density and average heat flux density were first increased and then decreased.The study of high bascity CaO-SiO₂-Al₂O₃ system shows that when mgo<9mol%,MgO plays the role of network destruction in structure,and the O^2-of ionization produces lower the polymerization degree of the system.When MgO content reaches12mol%,MgO interacts with Al₂O₃,The result is that there is a small amount of magnesia-alumina spinel in the system,which changes the stability of the slag structure and causes its performance to deteriorate.Thus,with the increase of MgO content,the viscosity first decreased and then decreased,the thermal stability increased first,then decreased,the maximum heat flux density decreased,and the average heat flux density increased.