Effects of the particle size and gas environment on afterburning reactions and explosion performance of aluminized HMX-based explosives

In this paper, confined explosions of HMX-based aluminized explosives in a spherical chamber are studied. The effects of aluminum particles on the afterburning reaction and explosive performance are obtained by changing the size of the particles and the gas environment. The results show that the concentration of oxygen in air is not sufficient to support complete combustion of aluminum particles. The estimated oxidation rate of aluminum particles is 87–93%, and it tends to decrease with increasing particle size. Part of aluminum particles oxidize with detonation products, and the reaction can last for hundreds of microseconds. However, the degree of oxidation between the large-sized aluminum particles and detonation products is small. A new method is used to estimate the initial energy of detonation by observing the time difference between sensing the initial light and the pressure wave. This method leads to a conclusion that some of the aluminum particles are oxidized during detonation and provide additional energy to the primary blast wave. Small micron-sized aluminum particles in the range of 48.9 nm to 46.7 $\mu$m extend the duration of the fireball.