Thermal Oxidation Characteristics and Kinetics of Micron Aluminum Powder in Different Ambient Oxygen Concentration Atmospheres

This paper examines the effect of oxygen concentration on the oxidation process and properties of aluminum particles, providing valuable insights for production and storage. Micron-grade aluminum powders were tested at heating rates of 5, 7.5, 10, and 15 K/min under oxygen concentrations of 7, 11, 15, 21, and 30 vol%. Results indicate a two-step mass gain oxidation process, with less pronounced mass gain at lower oxygen concentrations. SEM and XRD characterized the morphological and crystalline changes during oxidation. Lowering oxygen concentration from 30 vol% to 7 vol% increased the onset oxidation temperature by 17.1 °C. Increasing the proportion of inert gas in the atmosphere increases the ignition temperature of aluminum powder. The mathematical modeling approach of AKTS was used to decouple and analyze the thermal effects of simultaneous melting and oxidation, using the Friedman method to show that the apparent activation energy is about 350 kJ/mol in low-oxygen atmospheres (7 vol% and 11 vol%). The kinetics of aluminum oxidation were found to be closely related to the oxygen concentration, and based on the kinetics parameter, it is possible to predict a minimum limiting oxygen concentration.