Abstract
TiO2-Ca(1:2) mixture was milled in a planetary ball mill using cemented tungsten carbide vial and balls. It is supposed that in the mechanochemical reduction reaction of titanium oxide, TiO2+2Ca→ Ti+2CaO (ΔH=-326kJ/mol), a part of the reaction system is firstly ignited at about 830°C by mechanical energy and then the explosion reaction propagates to the whole of the reaction system by the reaction heat. This reaction process, in the range of weight of balls, 500-820g, as sample weight increases, time required for the reactions becomes longer, but the reduction reaction is accelerated and the side reactions are suppressed. In these experiments, the most suitable weight of the sample was about 110g for the reaction vessel of 250ml.
