Study On Metallurgical Behavior Of Fluorine Free Mold Powder

The addition of a certain amount of fluorine in the mold fluxes plays a role in stabilizing and regulating the metallurgical properties of the mold powder,but at the same time it brings a series of hazards.Affecting the working environment of the casting site and endangering the health of the staff to accelerate the aging of the equipment,erosion of the outlet and pollution of secondary cooling water.Development of fluorinefree flux is the objective requirements of environmental protection,metallurgical workers at home and abroad by the high priority.The difficulty of this technology is to find suitable fluorine substitute components,can fully coordinate the basic composition of the flux and suitable mineral phase.At present,the basic theory of fluorine-free mold flux is not perfect,the main metallurgical behavior and the coordination mechanism between them is not clear.In this paper,a fluorine-free mold powder with special contents such as TiO₂,Li₂ O,B₂O₃,Ca Cl₂,Mn O and so on was designed.The melting and crystallization behavior of mold powder under different fluorine substitutes were studied by using laboratory test instrument.Combined with Fact Sage software to analyze the microstructure of slag film and slag,to explore the reasonable composition and suitable mineral phase of fluorinefree mold powder,the main conclusions are as follows:1)the content of B₂O₃ increases,the area of low-melting liquid phase area increases,the melting point and viscosity of the flux decrease,and the content of B₂O₃ increases when the B₂O₃ content is more than 7% Crystal behavior is inhibited,the formation of the glass phase is facilitated,and the lubricating property of the slag is improved.2)When the content of TiO₂ is less than 9%,the area of low melting point increases and gradually approaches to Si O2,the viscosity of the slag decreases,TiO₂ is more than 9%,the crystallization temperature increases,and Ca Ti O3?Ca O·TiO₂?and other high melting point of the material caused by the increase in viscosity.3)Mn O and Li₂ O can provide O2-to make the complex anion disintegrate and reduce the viscosity.When the content of Ca Cl₂ is more than 3%,the main products are Ca2Al2 Si O7,Ca Si O3 and mullite.The crystallization temperature and crystallinity of the mold powder are improved,but the lubricating property of the mold powder is deteriorated.