Improving the Explosive Performance of Aluminum Nanoparticles with Aluminum Iodate Hexahydrate (AIH)

Abstract

A new synthesis approach for aluminum particles enables an aluminum core to be passivated by an oxidizing salt: aluminum iodate hexahydrate (AIH). Transmission electron microscopy (TEM) images show that AIH replaces the Al2O3 passivation layer on Al particles that limits Al oxidation. The new core-shell particle reactivity was characterized using laser-induced air shock from energetic materials (LASEM) and results for two different Al-AIH core-shell samples that vary in the AIH concentration demonstrate their potential use for explosive enhancement on both fast (detonation velocity) and slow (blast effects) timescales. Estimates of the detonation velocity for TNT-AIH composites suggest an enhancement of up to 30% may be achievable over pure TNT detonation velocities. Replacement of Al2O3 with AIH allows Al to react on similar timescales as detonation waves. The AIH mixtures tested here have relatively low concentrations of AIH (15 wt. % and 6 wt. %) compared to previously reported samples (57.8 wt. %) and still increase TNT performance by up to 30%. Further optimization of AIH synthesis could result in additional increases in explosive performance.

Ultra‐High Fidelity Laser‐Induced Air Shock from Energetic Materials

“…The results presented herein are in conflict with the published methods [5][6][7][8][9][10][11][12][13][14] for the LASEM technique, mainly: 1) transformation of the spatiotemporal data to velocitytime space, 2) use of the fifth-order polynomial for representation of the data, and 3) extrapolation of the fifth-order polynomial outside the experimentally measured dataset bound. However, a measurable difference was found between the baseline adhesive and HE materials, suggesting that the HE materials do indeed contribute to the laser-generated plasma, but outside the bounds of the length and time scales presented herein.…”

“…The target slides are oriented parallel to the optics table and mounted to a three-axis translational stage to permit laser ablation across the entire HE sample. Laser-pulse energy and spot size are chosen to replicate, as closely as permissible, the experimental parameters published by Gottfried [5][6][7][8][9][10][11][12][13][14]. The target is raised such that the laser focal point falls beneath the target surface as prescribed by Gottfried [6].…”

“…More recently, Gottfried et al published a similar technique possessing the capability to predict detonation-performance parameters of new and novel HE and/or HE formulations by demonstrating an empirically based correlation between detonation-performance parameters and the external shock wave velocity generated by laser ablation of sub-mg quantities of HE. The technique is referred to as LASEM: laser-induced air shock from energetic materials, and its novelty is challenging the axiom that energetic-material-performance characterization is unable to be completed at the sub-mg scale [5][6][7][8][9][10][11][12][13][14]. In brief, a small quantity (< 40 mg) of a target HE is spread onto a piece of double-sided adhesive that is adhered to a glass microscope slide.…”

“…The characteristic laser-induced shock velocity has been shown to correlate with multiple performance metrics, including: 1) heat of combustion, 2) detonation energy, 3) detonation pressure, and 4) published theoretical maximum density (TMD) bulk-detonation velocity for numerous HE materials characterized. Ultimately, it is claimed that linear calibration curves generated from these correlations permit an explosive-performance characterization for novel HE or HE formulations [5][6][7][8][9][10][11][12][13][14].…”

Characterization of Aluminum Powders: III. Non‐Isothermal Oxidation and Combustion of Modern Aluminized Solid Propellants with Nanometals and Nanooxides

“…Widely used cyclic nitramines (HMX, RDX, and CL‐20) are the common ingredients for the majority of modern solid propellants . The regulation of ballistic properties and the burning rate of such formulations are a complex task due to their chemical resistance to the majority of conventional catalysts (metal oxides , stearates , ferrocene , etc.). Nevertheless, nano‐sized metal powders and metal oxides were found to be competitive promoters of HMX, RDX, and CL‐20 decomposition.…”