Ignition of aluminum powders under different experimental conditions

This paper presents a brief review of experimental measurements of aluminum ignition temperature. Models used to describe aluminum ignition are also reviewed. It is shown that the current models cannot describe ignition of aluminum powders of different sizes and ignited under various experimental conditions. The paper further discusses properties of and phase changes occurring in the alumina scale existing on the surface of aluminum particles at different temperatures. Results of recent thermal analysis studies of aluminum powder oxidation are presented and it is shown that the stepwise oxidation of aluminum is caused by the sequence of polymorphic phase transitions occurring in the growing oxide film. Finally, the qualitative connection between the processes governing the oxidation of aluminum powders and the ignition of aluminum particles is made and an explanation for the experimentally observed wide range of aluminum ignition temperatures is suggested.