The Effect of Mechanical Activation on Non-isothermal Decomposition Kinetics of Ag2O–Graphite Mixture

Abstract

The effect of mechanical activation for 0, 2 and 4 h using high-energy planetary ball mill on the thermal decomposition kinetics of Ag2O–graphite powder mixture, i.e., mechanochemical decomposition, is systematically investigated by thermogravimetric analysis and a differential scanning calorimeter (DSC) in terms of a model-free advanced isoconversional method of Vyazovkin. The DSC results showed the mechanochemical decomposition shifts the reaction temperature in the range of 140–436°C (for as-received sample) to 170–335°C and 161–250°C after 2 and 4 h milling, respectively. The results show that decomposition of as-received Ag2O–graphite mixture with the average activation energy of 118.93±3.95 kJ mol−1 consists of two steps. The first step is a complex process with the participation of at least of two mechanisms, and the second step is a single-step process. The thermal decomposition of mechanically activated Ag2O for 2 h is a multi-steps process with the average activation energy of 99.38 ± 2.36 kJ mol−1. Moreover, the thermal decomposition of mechanically activated Ag2O–graphite powder for 4 h is a single-step process with the average activation energy of 93.68± 2.26 kJ mol−1.