Assessment of the Lubrication and Heat Transfer Controlling ability of the CaO-Al2O3-CaF2-based Mold Flux containing Metallic Particles

Abstract

Traditional lime-silica based mold flux for high Al AHSS causes a very rapid chemical reaction between SiO2 and Al. This chemical reaction causes serious problems in the continuous casting process, such as improper lubrication, lack of mold flux consumption, and so on. Alternatively, a structurally stable lime - alumina based mold flux can be developed to delay the chemical reaction. However, the crystallization behavior of the lime-alumina-based mold flux is difficult to control and easily occurs, which causes the mold lubrication to deteriorate rapidly. Therefore, this study designs a composition that can form structurally stable glass at high temperatures and suggests ways to control heat transfer and lubrication at the same time. In order to improve the structural stability of the lime-aluminate system, a structural analysis was conducted using Raman and Solid-state MAS NMR spectroscopy to find a composition that can optimize the mixed alkali effect. Next, a mechanism for effective controlling heat transfer based on Mie scattering was studied by dispersing metallic particles in a structurally stable mold flux. The change of extinction coefficient by Mie scattering of the metallic particles were investigated using FT-IR and UV-VIS. Also, Laser flash method was conducted for thermal conductivity measurement. Finally, the heat transfer ratios by both the conduction and radiation were simulated based on measurement of actual heat flux through mold flux film with an Infrared Emitter Technique (IET).