Formation of TiN and Ti(C,N) in TiO ₂ containing, fluoride free, mould fluxes at high temperature

Abstract

Fluoride containing mould fluxes may damage both the environment and casters, so the development of fluorine free mould fluxes is of great interest. The key issue for the development of fluorine free or low fluoride mould fluxes is to find a suitable crystal phase as a substitute for cuspidine. Some researchers have suggested that additions of TiO2 to fluxes can help to form perovskite (CaTiO3) as a suitable substitute for cuspidine. However, the rate of sticker breakouts was found to increase greatly after the use of the TiO2 containing, fluorine free mould fluxes in the continuous casting of peritectic steel grades. One of the possible reasons for this phenomenon is the formation of titanium nitride and carbonitride during the melting process of mould flux. This possible explanation has been proved in this study using both thermodynamic calculation and laboratory experiments on TiO2 containing, fluoride free mould fluxes.