Purification and Phase Evolution Mechanism of Titanium Oxycarbide (TiCxOy) Produced by the Thermal Reduction of Ilmenite

The phase evolution mechanism and purification of titanium oxycarbide (TiCxOy) synthesized via the carbothermal reduction of ilmenite are investigated. The reaction process and products of the performed carbothermal reduction are analyzed by means of X-ray diffraction (XRD), scanning electron microscopy-energy disperse spectroscopy (SEM-EDS), X-ray photoelectric spectroscopy (XPS) and enthalpy, entropy and heat capacity (HSC) thermodynamic software. According to the shapes of Ti 2p3/2 and Ti 2p1/2 peaks in XPS spectra, together with the XRD analyses, the reduction products of TiO, TiCxOy or TiC can be judged. The phase evolution mechanism involves FeTi2O5, Ti2O3, Fe, TiO, TiCxOy and TiC under enhancing the content of carbon. The phase evolution law can be written as FeTiO3 -> FeTi2O5 -> Ti2O3 + Fe -> TiO + Fe -> TiCxOy + Fe. Due to the incomplete reduction state of TiCxOy, the Delta G(theta) of TiCxOy is detected between TiC and TiO. TiCxOy could be attained under reduction conditions of Ti:C, 1:3-1:4 in argon atmosphere at 1550 degrees C after 2 h. Grinding, flotation and magnetic separation processes displayed that C, TiCxOy and Fe are not dissociated until the particle size of -38 mu m. TiCxOy and Fe can be separated by an iron-bath in a high temperature. 95.56% TiCxOy can be obtained, and resistance of TiCxOy is less than 0.05 omega.