Effects of CaF 2 on the Radiative Heat Transfer in Mould Fluxes for Continuous Steel Casting

Effects of CaF2 additions to mould fluxes have been investigated from the perspective of radiative heat transfer reduction to design mould flux for mild cooling. Glassy and crystallised mould flux samples were prepared so that the basicity of CaO/SiO2 was 1 and the Fe2O3 concentration was 1mass%, whereas the concentration of fluorine ranged between 2 and 14mass%. The samples were analysed by SEM-EDS and XRD. The apparent reflectivities and transmissivities were measured using two types of spectrophotometer with an integrating sphere. The replacement of CaO by CaF2 gives no effect on the optical characteristics of the glassy samples, not leading to radiative heat transfer reduction. In contrast, the replacement affects the optical characteristics of the crystallised samples and also the radiative heat transfer, which appear due to changes in the crystalline phases produced and the degree of crystallinity rather than the interaction between iron and fluoride irons.