Advances Toward the Development of “Green” Pyrotechnics

Gasless pyrotechnic delay compositions for time‐sequencing energetic events are reviewed. They are mixtures of powdered fuels and oxidants capable of a highly exothermic oxidation‐reduction reaction. Trends favor ‘green’ compositions targeted to replace compositions containing perchlorates, chromates, lead and barium. Thermite‐based reactions dominate but intermetallics (especially multi‐layered versions) and hybrids appear promising considering progress in self‐propagating high temperature synthesis technology. Improving computer modelling will require better description of condensed phase reactions. Progress was made with the development of “hot spot” models and expressing reactivity in terms of the number of contact points (or contact surface area) between particles. Promising processing advances include mechanochemical synthesis of reactive particle composites by arrested milling or comminution of cold‐rolled multilayer intermetallics. Dry mixing of reactive powders has made way for slurry mixing followed by spray drying.

Section: The Drive Towards "Green" Pyrotechnicsmentioning

confidence: 99%

Review of Gasless Pyrotechnic Time Delays

Focke

Tichapondwa

Montgomery

et al. 2018

“…In this case, the underlying smoke-generating mechanism is very different to colored smoke formulations: a typical HC mixture contains aluminum, zinc oxide and HC. During the combustion reaction, highly hygroscopic zinc(II) chloride is formed rapidly absorbing moisture from the air to generate a dense white smoke cloud [1,[5][6][7]. As a result, smoke yields above 100 % can be reached under optimal conditions mainly depending on the humidity.…”

Section: Introductionmentioning

confidence: 99%

“…During the combustion, highly toxic polychlorinated organic compounds can arise, which are believed to be carcinogenic [5,9]. Therefore, due to toxicity issues the HC-based obscurants are no longer produced [7]. Up to now, the AN-M83 smoke grenade based on terephthalic acid (TA) served as an environmentally benign alternative.…”

Section: Introductionmentioning

confidence: 99%

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Combining Higher Efficiency with Lower Costs: an Alternative Hexamine‐Based White Smoke Signal

Küblböck

Klapötke

2018

The effect of applying hexamine as main fuel in terephthalic acid-based white smoke formulations is discussed. For this reason, a simple four ingredients mixture only consisting of terephthalic acid, hexamine, potassium chlorate and a magnesium carbonate derivative was introduced. We started from a minimum amount of dye and constantly increased the dye percentage in 5.0 wt-% steps to investigate the influence on emerging smoke properties. This procedure ensures that the amount of dye present in the aerosol can be optimized to obtain the most persistent, thick white smoke cloud. Previous research on white smokes in our group indicated an overall higher smoke performance in terms of efficiency and advanced persistence by using 5-amino-1H-tetrazole as main fuel instead of sugar. From a costs point of view, hexamine would be favored, since it offers a low-cost alternative to 5-amino-1H-tetrazole.

“…Based on these results, it is recommended to find alternate wayst od emilitarize malfunctioning and weathered items found in military rangesa nd training areas. rates are expected to decline by about one ton per year in training ranges and manufacturing sites [6]. However,t he current stockpile still needst ob ea dequately managed.…”

Section: Introductionmentioning

confidence: 99%

Perchlorate Residues Emitted during the Use and Demilitarization of Simulators

Brochu

Turcotte‐Savard

2016

This study assessed the dispersion of perchlorate and dioxins and furans (PCDD/PCDF) residues following the use or demilitarization by blow‐in‐place of the Groundburst Simulator (GB) C1A1 and the Thunderflash (TF) C1A1 commonly used in the Canadian Armed Forces (CAF). The amount of unburned perchlorate residues per pyrotechnic device reached 0.8 and 43 mg for the regular use of TF and the GB, respectively. Their demilitarization by blow‐in‐place operations led to higher dispersion of unburned perchlorate residues, up to 6 and 2300 mg per TF and GB, respectively. Very high deposition rates were obtained for water‐soaked items: up to 460 mg per TF and up to 6600 mg for the GB. Dioxins and furans reached a maximum of 1 pg of Toxic Equivalent (TEQ) for the regular use, and 9 pg TEQ for the BIP operations. Based on these results, it is recommended to find alternate ways to demilitarize malfunctioning and weathered items found in military ranges and training areas.