Study on the oxidation mechanism of micron- and nano-sized aluminum powders influenced by alumina shell

Abstract

Thermal behaviors for aluminum particles at oxidative atmosphere gradually heating system were discussed. Heating micron- and nano-sized aluminum powders from room temperature to 1400℃ using thermal analysis method. The results showed that the reaction process for micron-sized aluminum particles can be divided into four stages which include the phase change of oxidized shell, increasing thickness of alumina shell, main broken shell oxidizing process and the phase change of alumina shell in high temperature. Thermal analysis for micro aluminum particles was carried out with shell thickness adjustments via ambient manual means. It turned out that the oxide layer thickness would have full limitation effects on the slow oxidation for micro aluminum particles with shell structure when it was increased above twice of the original thickness. The limitation effects of oxide shell thickness on the heating processes in gradually heating system were proposed. Humidity environment can make the thickness of alumina increase in a certain range when the particles are in nano-scale. Complete oxidation processes were observed but an increase of the oxidation temperature was identified.