Equilibrium phase relations of CaO–SiO2–TiO2 system at 1400 °C and oxygen partial pressure of 10−10 atm

Abstract

The equilibrium phase relations and liquidus contours for the TiOx-containing oxide system in reducing atmospheres are of importance in understanding the smelting process of Ti-containing resources. Equilibrium - quenching experiments were conducted at 1400 °C for the CaO–SiO2-TiOx system at oxygen partial pressure of 10−10 atm controlled by a CO/CO2 gas mixture. The equilibrium phase compositions were analyzed by scanning electron microscopy - energy dispersive X-ray spectrometry. Perovskite, wollastonite, rutile, and silica were found to coexist with liquid oxide. The 1400 °C isotherm was then constructed for the CaO–SiO2-TiOx system, and the results revealed that lower oxygen partial pressures led to shrinkage of the rutile and wollastonite primary phase areas. The comparisons with the calculated sections by FactSage and MTDATA indicated that the oxygen partial pressure has an obvious influence on the molten phase domain and clear deviations from experimental data mainly existed in the primary phase field of rutile. Therefore, the present results are significant for updating the current TiOx-containing thermodynamic databases, giving a deeper understanding of the related high temperature processes.