Oxidation Kinetics of Magnesium Powder Particles in Non-Isothermal Condition

In this research, the effect of heating rate on oxidation kinetics of magnesium powder particles under non-isothermal conditions was studied. For this purpose, differential thermal analysis (DTA) and thermogravimetry analysis (TGA) was done on magnesium powder particles at three heating rates of 5, 10 and 20 K min-1 up to 1000 °C under air atmosphere. Also, in order to better understand the oxidation process of magnesium powder, three temperatures were selected according to the DTA curve at a heating rate of 20 K min-1. Then, samples of magnesium powder were heated up to these three temperatures with heating rate of 20 K min-1 and were subjected to X-ray diffraction (XRD) and scanning electron microscopy (SEM) for phase and microstructural analysis. Then, kinetic studies were performed using some isoconversional methods such as Starink and Friedman as well as direct and indirect fitting methods. The activation energy (E) and pre-exponential factor (lnA) for oxidation of magnesium powder were in the range of 327-956 kJ mol-1 and 45-135 min-1, respectively. The reaction models for heating rates of 5, 10 and 20 K min-1 were obtained to be A3/2, R2 and D1, respectively.