V. Sundaram et al., REACTION-PATH IN THE MAGNESIUM THERMITE REACTION TO SYNTHESIZE TITANIUM DIBORIDE, Journal of materials research, 12(10), 1997, pp. 2657-2664
TiB2, along with MgO and Mg3B2O6, was formed by a thermite reaction be
tween Mg, amorphous B2O3, and TiO2 powders in argon. The mixture 5Mg-T
iO2-B2O3 along with binary mixtures and single components were analyze
d 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 sta
te 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 beco
me consumed in the formation of oxides, nor time for oxidation degrada
tion of TiB2.