Investigation on mechanochemical behavior of the TiO2–Mg–C system reactive mixtures in the synthesis of titanium carbide

Abstract

TiC–MgO composite was synthesized using mixtures of TiO2, Mg, and wood dust via a mechanochemical process. The influence of various Mg values (0–2.4mol) on the titanium carbide formation and the mechanism of reactions during the milling of TiO2–Mg–C mixture were investigated. Phase transformations, grain size, strain, lattice parameters, and morphology of the powders during the milling process were examined using X-ray diffractometry (XRD) and scanning electron microscopy (SEM). Thermodynamic calculations revealed that the Mg value played a main role. Consequently, the overall reaction enthalpy and adiabatic temperature (Tad) changed with variation of the magnesium content. Experimentally, after 10h of milling, TiC was synthesized in the mixture powder with stoichiometric ratio (Mg=2mol). The type of reactions was mechanically induced self-sustaining reaction (MSR). In addition, at lower Mg content (Mg=1.5), the heat resulted from magnesiothermic reaction also activated the carbothermal reduction. Further decrease in the Mg value (Mg=0.5 and 1mol) resulted in formation of MgTiO3 as a major phase. Using the excess Mg value (Mg=2.2 and 2.4molMg) as a diluent agent led to formation of Mg2TiO4 besides the MgO and TiC phases.