Influence of the process variables on mechanosynthesis of AgI–Ag 2O–WO 3 system

Abstract

The work studies the effect of selected milling variables on mechanosynthesis of the materials formed in the AgI–Ag 2O–WO 3 system. These variables were: a rotation speed, a milling time, a ball-to-powder mass ratio, a process control agent and a level of preliminary grinding of the reactant powders. The mechanosynthesis was carried out using Fritsch Pulverisette 7 and Fritsch Pulverisette Premium Line planetary mills. The X-ray diffraction method was applied for phase identification in the final product and for determination of their relative contents. It has been found out that: the synthesis leads to amorphous products and its efficiency is enhanced when: i) rotation speed and milling time are increased, ii) ball-to-powder mass ratio decreased and iii) starting powders are pre-ground. When the substrates are milled too long or applied milling speed is too fast, exceeding 600 rpm, then the process of amorphisation is impeded. The limit values of rotation speed and milling time are interrelated. Additionally they depend on the type of mill and applied mode of work. Preliminary grinding of the starting compounds enhances the milling efficiency. Addition of acetone, a control agent, to the milling batch reduces efficiency of production of amorphous phase.