PROJECT TITLE :

Effect of milling on the combustion synthesis of ternary system B2O3, Mg and C

ABSTRACT:

The preparation of boron carbide nanoparticles was investigated by coupling a highly exothermic B2O3-Mg thermite reaction with a weakly exothermic B4C formation reaction. An experimental study for the formation of B4C nanoparticles was conducted by combustion synthesis in the mode of thermal explosion. The mixture of B2O3:Mg:C with stoichiometry 2:7:1 was milled for 1, 3, 6, 12, 24 and 36 h. The milled powders up to 12 h were used for the combustion reaction. The combustion reactions were carried out in an inert atmosphere (Ar) at 900 C. The samples are investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The XRD analysis of all samples after combustion indicated that the main phase was MgO along with Mg3(Bo3)2 and B4C as secondary phases. The XRD analysis of samples after leaching of the combustion product detected boron carbide as a main phase and unreacted graphite as minor phase, while the graphite was the least for products of 12 h milled powders. The TEM image of this sample showed nanometric crystallite of less than 60 nm.