Effect of metallic agent on the carbothermic reduction of titanium dioxide in order to produce titanium carbide

The effect of metallic agents such as aluminium, magnesium and mixture of magnesium-zinc was studied on the carbothermic reduction of titanium dioxide in this research under mechanical milling. The mechanical milling runs were done in a planetary ball mill in different times. The stoichiometric mixtures of TiO2-Mg-C, TiO2-Mg-Zn-C and TiO2-Al-C were prepared based on stoichiometric ratios for each reaction. The acid washing process using 2 N HCl solution was done to remove the soluble phases after finishing mechanical milling of each sample. The isothermal heating was done at temperature of 1000 ºC for one hour for solid residues of acid washing under flowing of argon atmosphere. The analysis of products and phases was done using XRD and the microstructure of samples studied by SEM. The results showed the reaction between titanium dioxide and carbon would be exothermic after the adding metallic agent. The reaction progresses via MSR mode for the mixture of TiO2-Al-C in milling conditions and the products were titanium carbide and alumina in the 5 h milled sample. The reduction reaction however progressed via intermediate titanium dioxide in the milled samples for mixtures of TiO2-Mg-C and TiO2-Mg-Zn-C. The signs of titanium carbide and intermediate titanium oxide such as Ti2O3 were observed in the milled mixtures of TiO2-Mg-C and TiO2-Mg-Zn-C after isothermal heating under argon atmosphere. The signs of Ti2O3 phase reveal that the reduction reaction of titanium dioxide does not complete after 10 h milling when metallic agents such as magnesium and/or magnesium-zinc mixture are used.