Thermodynamic Modeling of Pyrotechnic Smoke Compositions

Abstract

Some of the most effective visible obscurants for military applications are toxic or incendiary or present serious logistical complications. Sustainable alternatives are needed to mitigate the risks of human exposure and environmental contamination. The FactSage 6.4 software package was used to model the thermodynamics of pyrotechnic smoke compositions based on boron carbide, hexachloroethane, and phosphorus. The computational results are shown to be relevant in light of prior experimental observations. Boron phosphide is proposed as a benign source of phosphorus for next-generation pyrotechnic smoke compositions. The thermodynamics of the BP–KNO3 system have been studied computationally. The results indicate that certain stoichiometries should produce elemental phosphorus upon combustion. The properties of the BP–KNO3 system are examined considering the functional requirements of smoke munitions.

Preparation, Characterisation and Performance of Microencapsulated Red Phosphorus

“…With the data listed in Table 4, the entropy of activation (DS # ),enthalpy of activation (DH # ), and free energy of activation (DG # ) of the oxidation of RP and MRP are obtained from equation (3), equation (4) and equation (5).…”

“…The main military applications for phosphorus and its compounds are igniters, incendiaries, screening smoke ammunition, flame, smoke signals and decoys [1][2][3]. However, RP-based smoke compositions slowly degrade in the presence of air and trace moisture, producing acids that can corrode munition components and phosphine gas that is highly toxic and flammable [4,5]. Additionally, RP-based smoke compositions are generally very sensitive to unintended ignition by friction [6].…”

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

“…There are several promising approaches in the experimental stage in the literature: Shaw et al discussed the use of boron carbide as pyrotechnic fuel in combination with potassium nitrate as a possible alternative to HC-based smoke [23]. In a further theoretical study, they compared the thermodynamics of this B 4 C/KNO 3 composition with a boron phosphide (BP/KNO 3 ) system [25]. In this case, BP is expected to function as in situ phosphorus source, since the commonly applied red phosphorus suffers from the formation of toxic phosphine gas and phosphoric acid during combustion [25,26].…”

Internal Temperature and Pressure and the Rate of Mass Loss from Hand Thrown Smoke Grenades

“…There have been a small number of publications regarding smoke compositions, but the majority are either based around the now nearly obsolete Hexachloroethane white smokes [1] or the use of red phosphorus in obscurant smoke, whether empirical or modelling [2]. In the more spe-cific case of coloured smokes, published data has been primarily based upon toxicity concerns regarding the volatilised dyes [3,4], although there does exist one paper examining the safe performance of suitable fuel/oxidiser compositions in a laboratory context [5] and a study of some thermal properties of commonly used dyestuffs [6].…”