Mechanism of titanium carbide formation in mould flux investigated by TG-FTIR, DSC and XRD

As a crucial functional material in the continuous casting process, mould fluxes play a significant role in ensuring smooth operation and improving the quality of cast billets. To mitigate the environmental impact of fluorides in mould fluxes, TiO 2 has been introduced as a network former to reduce viscosity and melting temperature. The formation of perovskite instead of cuspidine also contributes to controlled heat transfer. However, preventing the formation of titanium carbide (TiC) under high-temperature conditions remains challenging. Experimental results indicate that during heating, both CaO–SiO 2 –TiO 2 and CaO–SiO 2 –CaF 2 –TiO 2 slag systems react to form perovskite. TiO 2 participates more readily in solid-state reactions with CaO than CaF 2 does, thereby inhibiting the formation of cuspidine. Furthermore, in carbon-containing CaO–SiO 2 –TiO 2 systems, TiC forms along with CO at elevated temperatures. It is revealed that TiC formation does not result from the direct reaction between TiO 2 and C, but rather from the reaction between CaTiO 3 and C. Under high-temperature carbon-rich conditions, carbon reduces perovskite to form TiC. Consequently, in contrast to fluorine-based fluxes, titanium-bearing mould fluxes require careful optimisation of carbon content to prevent TiC precipitation.