Reaction path in the magnesium thermite reaction to synthesize titanium diboride

TiB2, along with MgO and Mg3B2O6, was formed by a thermite reaction between Mg, amorphous B2O3, and TiO2 powders in argon. The mixture 5Mg-TiO2-B2O3 along with binary mixtures and single components were analyzed using differential thermal analysis (DTA) and x-ray diffraction (XRD). Large (25 g) specimens were also ignited in bulk using a resistance-heated nichrome wire. The reaction path in forming TiB2 in the three component mixture was deduced. Mg reduces TiO2 and B2O3 to form Ti and MgB2, respectively, which in turn react to form TiB2, In an oxidizing atmosphere, the significant speed of the reaction permitted solid state reaction to form TiB2 before atmospheric oxygen could diffuse into the powder mass and react to form oxide phases. Thermite reactions in air have the advantage (over furnace heating in air) of not providing time at elevated temperatures for Mg and intermediate products to become consumed in the formation of oxides, nor time for oxidation degradation of TiB2.