Analysis of Oxidation Characteristics of Micron-Scale Aluminum Powders at Different Heating Rates

The oxidation characteristics of 1~2 μm aluminum powders at different heating rates were studied by TG-MS, X ray diffractometer (XRD) and scanning electron microscope (SEM). The relationship between the thickness of the oxide layer_the activation energies and the heating rate were analyzed. The results show that the oxidation of 1~2 μm aluminum powders can be divided into five stages, and the mechanism of polycrystalline phase transition is suitable for 1~2 μm aluminum powders. The rupture of the oxide layer induced by the crystal transformation of the alumina and the expansion of the molten aluminum core is the main cause of rapid oxidation. A smaller weight gain peak in the DTG curve occurs in the third stage, due to the emergence of θ-Al₂O₃ at the surface. The temperature peak occurs earlier when the heating rate decrease. It is also found that the selection of the diffusion force only slightly influence the computation of the activation energy, and the relationship between the activation energies and the heating rate is not consistent at all oxidation stages.