Oxidation kinetics of magnesium particles determined by isothermal and non-isothermal methods of thermogravimetric analysis

Knowledge of the oxidation kinetics magnesium (Mg) particles is important for development advanced propulsion and power systems based on combustion metals. However, reports high-temperature Mg powders in oxygen are contradictory. In present work, spherical non-spherical (flakes) O2 flow was investigated using isothermal non-isothermal thermogravimetry. Three fractions powder were tested, with average sizes about 30, 60, 300 ?m. The all complete at temperatures lower than melting point Mg, 650 °C. Friedman analysis thermogravimetric (TG) data has shown that activation energy exhibits only small fluctuations during a large part process, which indicates process can be modeled as single-step reaction. Model-based Avrami-Erofeev model simultaneous nucleation growth provides best fit experimental TG curves. Scanning electron microscopy oxidized submicron grains, consistent model. Mampel-Delmon 30 60 ?m particles, relatively slow, leading to sigmoidal curve, described by three-dimensional equation. An increase particle size decreases dimension this equation, flakes, entire considered non-protective oxide layer. apparent likely range 200 – 230 kJ/mol, independently shape.