Investigation on heat transfer performance of fluoride-free and titanium-bearing mold fluxes

Fluorine erodes continuous casters and pollutes the environment. In order to reduce the damage caused by fluorine, it is necessary and urgent to carry out research on fluoride-free mold fluxes. There has been little research done on the heat transfer performance of fluoride-free mold fluxes either domestically or abroad. The present work adopted TiO2 to take the place of fluorine in mold fluxes and studies its heat transfer performance. Heat flux simulation equipment was developed and the heat flux density of titanium-bearing mold fluxes containing TiO2 was measured; in addition, a solid slag film was obtained. The crystallization behavior and the change of activation energy for crystallization of the slag film was analyzed. Our results show that when the TiO2 content is increased, the heat flux density of fluoride-free mold fluxes decreases, the crystallization activation energy of mold fluxes is diminished and the crystallization ratio of mold fluxes increases, and the mineral phase of the slag film turns from akermanite into perovskite. When the basicity is increased, the heat flux of fluoride-free mold fluxes is reduced, the crystallization ratio of mold fluxes increases and the mineral phase of the slag film turns from unitary akermanite into the coexistence of two phases of akermanite and perovskite. Furthermore, the capability of fluoride-free and titanium-bearing mold fluxes to control heat transfer is better, so it can be expected to replace industrial slag containing fluorine completely.