A feature on ensuring safety of superfine explosives

To probe the dependence of particle size on the safety of nitroamine explosives, coarse RDX and HMX were comminuted to nanometer particles by an improved superfine mill. Their thermolysis characteristics were studied by thermal analysis and described via calculating some thermodynamic and kinetic parameters such as the activation free-energy (ΔG ^≠), activation enthalpy (ΔH ^≠), activation entropy (ΔS ^≠), apparent activation energy (E), critical temperature of thermal explosion (T _b), and critical heating rate of thermal explosion ( $ ({\text{d}}T/{\text{d}}t)_{{T_{\text{b}} }} $ ). After comminuted, the values of T _b and $ ({\text{d}}T/{\text{d}}t)_{{T_{\text{b}} }} $ were increased. However, the values of ΔH ^≠, ΔS ^≠, ΔG ^≠, and E for nanoexplosives were close to those of microexplosives, which mean decreasing particle size into nanometer did not distinctly influence the thermolysis characteristic of nitroamines. The safety of the nanoexplosives was practically assessed by testing their impact, friction, and shock sensitivities. Results indicated that nano nitroamines presented obviously higher safety than the micro-counterparts. Especially in Small Scale Gap Test, the shock sensitivity of nano-RDX and nano-HMX decreased by about 45 and 56% compared with that of micro-RDX and micro-HMX, respectively.