Non-isothermal oxidation and kinetic analysis of pure magnesium powder

With high energy densities, metals appear as innovative energy carriers. In the present study, magnesium powder is considered as fuel for energy production through slow combustion. Thermogravimetric analyses (TG) were carried out to extract the kinetic parameters and determine the mechanism of the overall slow combustion reaction. TG experiments were performed under synthetic airflow and under different heating rates (from 1 to 20 degrees C min(-1)) from ambient temperature to 900 degrees C, with two Mg size fractions. The optimal kinetic parameters were determined solving a kinetic model and applying an optimization procedure, both using the Scilab software. The Avrami-Erofeev reaction function of second order, which is a nucleation model, gave the best results for both size fractions. The activation energies were found equal to 146.1kJmol(-1) and 290.0kJmol(-1) for the 20-50 mu m and 50-71 mu m fractions, respectively. The corresponding optimal pre-exponential factors were found equal to 1.2x10(6) s(-1) and 2.0x10(15) s(-1), respectively.