Oxidation mechanism of micron-sized aluminum particles in Al-CO₂ gradually heating system

Micron-sized aluminum powders were heated in carbon dioxide atmosphere through differential scanning calorimetry (DSC) method in this work. Aluminum powders were oxidized into four distinct stages from room temperature to 1500°C. Stage I, amorphous alumina shell turns to γ-Al₂O₃ phase from room temperature to 620°C. Stage II, accompany with the aluminum core melting, alumina shell becomes thicker and fragile at the temperature around 667°C which is the melting point of aluminum. Stage III, in the temperature range of 690-1150°C, alumina shell was broken partially because of the inside pressure. Liquid aluminum spurts out through the weak point which becomes cracks on the surface just like volcano eruption and then oxidized by CO₂ while the temperature increased from 700°C to 900°C. Stage IV, alumina changes to stable α-Al₂O₃. From what was presented above, a mechanism of micron-sized aluminum particle oxidation in CO₂ under gradually increasing temperature condition was proposed as "eruption model". (paper)