Study of Solidification and Heat Transfer Behavior of Mold Flux Through Mold Flux Heat Transfer Simulator Technique: Par
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flux plays very important roles in the continuous casting of steels, and one of the main functions is to infiltrate into the gap between the solidified shell and water-cooled copper mold gap and solidify against the water-cooled copper mold to provide lubrication and the control of heat transfer between the shell and mold.[1,2] The infiltrated mold flux film in between the gap is usually composed of three layers, depending upon the temperature gradient between the steel shell and copper mold, and its chemical compositions, i.e., a liquid layer next to the steel shell, a solid glassy layer against the mold wall, and a crystallized layer in between.[3–5] The partially crystallized slag film can reduce the heat transfer rate by scattering radiation and forming the air gap at the interface between the solidified mold flux and copper mold.[6,7] Therefore, the control of heat transfer in the mold can be achieved by the proper selection of the chemical composition of the mold flux. Intensive research has been conducted to investigate the in-mold heat transfer behaviors of mold flux using the following methods. Ohmiya et al.[8] and Yamauchi et al.[9] measured both the heat conductivity and FANJUN MA, Lecturer, YONGZHEN LIU and HAIHUI ZHANG, Graduate Students, and WANLIN WANG, Shenghua Professor, are with the School of Metallurgy and Environment, Central South University, Changsha, 410083, Hunan, P.R. China. Contact e-mail: [email protected] Manuscript submitted April 8, 2015. Article published online May 19, 2015. 1902—VOLUME 46B, AUGUST 2015
interface thermal resistance through the method of one-dimensional steady-state plate. Cho et al.[10,11] concluded that the interfacial thermal resistance between the mold and solidified mold flux controls the in-mold heat transfer and the formation of interfacial thermal resistance is attributed to the shrinkage of the solidified mold flux. Schwerdfeger et al.[12,13] suggested that there are both radiative and conductive heat transfer across the mold flux layer and the contact thermal resistance at the copper side is almost independent upon the layer thickness. Shibata et al.[14] studied the overall thermal resistance by pouring the molten slag onto the copper mold and measuring transient heat transfer to the mold. Yovermeulen et al.[15] identified the heat transfer of the mold flux qualitatively by measuring the surface temperature of copper mold in the copper finger test. Ozawa et al.[16] measured the lattice conductivities, refractive indices, and absorption/extinction coefficients of glassy and partially crystallized mold fluxes using the hot wire method. Nishioka et al.[17] studied thermal diffusivity, heat capacity, and thermal conductivity of CaOSiO2 and CaO-SiO2-Al2O3 system slags through the square-wave pulse heat method. Susa et al.[7] and Diao et al.[18] studied the effect of crystallization of mold flux on the heat transfer rate by measuring the radiative thermal properties of mold slag, such as the absorption and extinction coefficient using a spectrophotometer. Wang et al.[19–21] investigated
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