Fluoride evaporation and crystallization behavior of CaF2–CaO–Al2O3–（TiO2） slag for electroslag remelting of Ti-containing steels
来源期刊：International Journal of Minerals Metallurgy and Materials2016年第6期
论文作者：Cheng-bin Shi Jung-wook Cho Ding-li Zheng Jing Li
文章页码：627 - 636
摘 要：To elucidate the behavior of slag films in an electroslag remelting process, the fluoride evaporation and crystallization of CaF2–CaO–Al2O3–（TiO2） slags were studied using the single hot thermocouple technique. The crystallization mechanism of TiO2-bearing slag was identified based on kinetic analysis. The fluoride evaporation and incubation time of crystallization in TiO2-free slag are found to considerably decrease with decreasing isothermal temperature down to 1503 K. Fish-bone and flower-like CaO crystals precipitate in TiO2-free slag melt, which is accompanied by CaF2 evaporation from slag melt above 1503 K. Below 1503 K, only near-spherical CaF2 crystals form with an incubation time of less than 1 s, and the crystallization is completed within 1 s. The addition of 8.1wt% TiO2 largely prevents the fluoride evaporation from slag melt and promotes the slag crystallization. TiO2 addition leads to the precipitation of needle-like perovskite（CaTiO3） crystals instead of CaO crystals in the slag. The crystallization of perovskite（CaTiO3） occurs by bulk nucleation and diffusion-controlled one-dimensional growth.
Cheng-bin Shi1，Jung-wook Cho2，Ding-li Zheng1，Jing Li1
1. State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing2. Graduate Institute of Ferrous Technology, Pohang University of Science and Technology
摘 要：To elucidate the behavior of slag films in an electroslag remelting process, the fluoride evaporation and crystallization of CaF2–CaO–Al2O3–（TiO2） slags were studied using the single hot thermocouple technique. The crystallization mechanism of TiO2-bearing slag was identified based on kinetic analysis. The fluoride evaporation and incubation time of crystallization in TiO2-free slag are found to considerably decrease with decreasing isothermal temperature down to 1503 K. Fish-bone and flower-like CaO crystals precipitate in TiO2-free slag melt, which is accompanied by CaF2 evaporation from slag melt above 1503 K. Below 1503 K, only near-spherical CaF2 crystals form with an incubation time of less than 1 s, and the crystallization is completed within 1 s. The addition of 8.1wt% TiO2 largely prevents the fluoride evaporation from slag melt and promotes the slag crystallization. TiO2 addition leads to the precipitation of needle-like perovskite（CaTiO3） crystals instead of CaO crystals in the slag. The crystallization of perovskite（CaTiO3） occurs by bulk nucleation and diffusion-controlled one-dimensional growth.
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