Shear thinning behavior of various mold flux systems
Seung-Ho Shin1，Jung-Wook Cho2，Qing Liu3
1. Department of Materials Science and Engineering， Pohang University of Science and Technology， Pohang 790-784， Korea 2. Graduate Institute of Ferrous Technology， Pohang University of Science and Technology， Pohang 790-784， Korea 3. State Key Laboratory of Advanced Metallurgy， University of Science and Technology Beijing， Beijing 100083， China
Abstract：During the continuous casting process， mold flux plays a crucial role in controlling lubrication to achieve better performance on the castability and quality of cast products. Out of the various thermo-physical properties of mold flux， viscosity is essential parameter to appreciate the lubrication of mold flux. Recently， shear thinning property of molten mold flux had been confirmed by many researchers including present authors. This particular property might be beneficial for the actual continuous casting due to the fact that actual operation needs high viscosity at mold top surface where shear rate is approximately 10-40 s－1in order to alleviate slag entrainments whereas the viscosity should be low at mold wall where shear rate is roughly 100-1 000 s－1 in order to maximize lubrication capability. The present study attempts to characterize viscoelasticity named shear thinning property of CaO-CaF2-SiO2， CaO-CaF2-B2O3-SiO2 and CaO-CaF2-SiO2-Si3N4 based mold flux systems by measuring their viscosity with a rotational viscometer， equipped a furnace under controlled oxygen fugacity at the temperature of 1 623 K. Also， Raman spectroscopy and XPS analyses have been conducted to understand the relationship between viscoelasticity and structure of mold fluxes. According to the results， all the mold fluxes tested have a property of shear thinning in which viscosity decreases as the shear rate increases. Oswald-De Waele power law model has been applied to quantify the degree of shear thinning for each mold flux， which showed that the degree of polymerization for each mold fluxes is largely proportional to the intensity of shear thinning behavior.
SHIN Seung-Ho，CHO Jung-Wook，刘 青. 不同结晶器保护渣的剪切变稀行为[J]. 中国钢铁期刊网, 2016, 35(4): 69-78.
Seung-Ho Shin，Jung-Wook Cho，Qing Liu. Shear thinning behavior of various mold flux systems. Chinese Journal of Iron and Steel, 2016, 35(4): 69-78.