Mechanical activation of aluminothermic reduction of NiO by high energy ball milling

The effect of mechanical activation on NiO–Al reaction has been investigated by carrying out high energy ball milling using toluene as the process controlling agent. NiO reduction reaction progresses gradually and a maximum of 70% reduction has been observed in 20 h of milling. Amorphous alumina forms as the product of NiO reduction and it transforms to stable α-Al2O3 at 1000 °C via the formation of metastable transition γ-Al2O3. The activation energy of NiO reduction in unmilled powder is 277 kJ/mol whereas in 20 h milled powder the activation energy has been reduced to 150 kJ/mol.