Mechanosynthesis of nanocomposites in TiO2–B2O3–Mg–Al quaternary system

The mechanochemical behavior of TiO2–B2O3–Mg–Al quaternary system to synthesize various composite nanopowders was studied. A mixture of boron oxide and titanium dioxide powders along with different amounts of magnesium and aluminum was milled using a high-energy planetary ball mill to persuade necessary conditions for the occurrence of a mechanically induced self-sustaining reaction (MSR). Results showed that the formation of composite nanopowders was influenced strongly by the reducing agents content. In the absence of Al (100 wt% Mg), TiB2 nanopowder was formed after 34 min of milling. In the presence of x wt% Mg–y wt% Al (x=40 and 70; y=100−x), mechanical activation was completed after 37–40 min which caused the formation of TiB2–MgFe0.6Al1.4O4 composite nanopowders. In the case of 10 wt% Mg–90 wt% Al, a ternary nanocomposite (TiB2–MgAl2O4–Al2O3) was produced after 43 min of milling. Besides, Al2O3–TiB2 nanocomposite was formed after 90 min of milling in the absence of Mg (100 wt% Al). From the SEM images, mechanochemical process reached a steady state after short milling times where the particles have become homogenized in size and shape. The reaction mechanism steps were proposed to clarify the reactions occurring during mechanochemical process.