Mohammad Hossein Khazaei Feizabad - Department of Material Engineering and Metallurgy, Shahid Bahonar University of Kerman, Kerman, Iran
Alireza Arab - Khash Education Department, Khash Dr. Hesabi Research Center

In the present study, MgO-ZrB۲ nanocomposite was produced by the mechanochemical process of Mg, ZrO۲ and H۳BO۳ stoichiometry mixture. For this purpose, the powder mixture was mechanically milled for different milling times at ۳۵۰ and ۴۵۰ rpm in Ar atmosphere. The ball to powder ratio was ۱۰:۱. Also, to control the process and prevent the agglomeration and sticking of powders, process control agent was employed. The results of X-ray diffraction, Differential scanning calorimetry (DSC) and scanning electron microscopy showed that lower milling speed (۳۵۰ rpm) leads to gradually progress reaction in contrast with higher milling speed (۴۵۰ rpm) which cause to the combustion reaction. Also when the milling speed was ۴۵۰ rpm the Mg۲Zr۵O۱۲ was created which confirms combustion reaction has taken place. The average grain size of MgO and ZrB۲after ۱۵ h of milling at ۴۵۰ rpm, were ۹۰ and ۴۷ nm, respectively. For determination of reaction activation energy, DSC was done for the sample milled for ۲۵ h at ۳۵۰ rpm with heating rates of ۲۰, ۳۰ and ۴۰ oC/min in Ar atmosphere. The estimated value for the reaction activation energy of reaction was determined about ۱۷۹.۵ kJ/mol.

MgO nanocomposite, Mechanochemical reaction, DSC analysis, Activation energy