Ignition sensitivity and explosion behaviors of micron-sized aluminum powder: Comparison between flake aluminum powder and spherical aluminum powder

The addition of aluminum powder can increase the energy of the combustion system. The spherical aluminum powder can be flaked by the ball milling technology, which can remove the oxide layer on the particle surface and improve the reaction activity. However, the ignition sensitivity and thermal behavior of flake aluminum powder should arouse extensive attention. In this paper, experimental measurements and statistical analysis are carried out for the ignition characteristics and explosion mechanism of micron-sized flake and spherical aluminum powder. Because the oxide layer is an important component in the oxidation process of aluminum powder, a theoretical model to calculate its equivalent thickness and fracture conditions is proposed. Moreover, the surface effect has a significant impact on intensifying the explosion hazard. For micron-sized aluminum powder, the relationship between ignition temperature and particle size is as follows: T_i∝d₃₂^0.2. The maximum rise rate of explosion pressure for flake aluminum powder is 4.19 times than that for large spherical aluminum powder. Furthermore, the MEC results corresponding to the ignition probability are obtained by using the Logistic regression model. Present work recommends that the safety design should be based on the MEC prediction result of p = 0.5.