Experimental investigations of the controlled explosive synthesis of ultrafine Al$_2$O$_3$

The relation between the parameters of mixed explosives [combinations of Al(NO$_3$)$_3$ $\cdot$ 9H$_2$O powder, RDX powder, and/or polyethylene foaming particles] and the phase and dimension of ultrafine Al$_2$O$_3$ is studied in this paper. Experimental results indicate that mixed explosives with a high density of 1.8 g/cm$^3$ are adapted to prepare high-temperature $\alpha$-Al$_2$O$_3$. Ultrafine $(\alpha+\gamma)$-Al$_2$O$_3$ with $\alpha$-phase dominance is synthesized by the detonation of charges with a medium-high density of 1.3 g/cm$^3$. Explosives with a medium-low density of 0.8 g/cm$^3$ synthesize low-temperature pure $\gamma$-Al$_2$O$_3$.