Laser ablation of aluminized RDX with added ammonium perchlorate or ammonium perchlorate/boron/magnesium hydride

Abstract

The laser-ablated reaction process of two aluminized cyclotrimethylene-trinitramine (RDX) explosives with additives is presented, one formulation is RDX/aluminum (Al) /ammonium perchlorate (AP) and named AH, the other is RDX/Al/AP/Boron (B)/magnesium hydride (MgH2) and named BH. Laser ablation combined with a high-speed photography and an emission spectrometer in this paper provides a high time-resolution observation of the reaction process of energetic materials in laboratory scale. A sample plate with an array of cylindrical holes was used to load the explosive powders for high-throughput studies, and a complete fresh sample was ablated each time to ensure the consistency of the sample status. From the laser-ablated images, AH exhibits a longer combustion duration than aluminized RDX with no additional additives, and BH has an even longer combustion duration than AH. Both AH and BH show a monotonic decreasing trend in luminous intensities, but AH has higher intensities than BH from 3 to 30 µs. In addition to the observation of AlO molecular emission lines in the spectra of AH and BH, neutral magnesium (Mg I) emission lines were observed in the spectra of BH. The spectral distribution with time indicates that the oxidation reaction of Al is the main reason leading to persistent combustion in AH and BH. Overall analysis directly reveals that AP promotes the combustion of AH and makes the afterburning of Al with ambient air less significant, and B/MgH2 prolongs the combustion duration of BH.