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

TiC-MgO composite was synthesized using mixtures of TiO2, Mg, and wood dust via a mechanochemical process. The influence of various Mg values (0-2.4 mol) 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 10 h of milling, TiC was synthesized in the mixture powder with stoichiometric ratio (Mg = 2 mol). 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 1 mol) resulted in formation of MgTiO3 as a major phase. Using the excess Mg value (Mg = 2.2 and 2.4 mol Mg) as a diluent agent led to formation of Mg2TiO4 besides the MgO and TiC phases.