In‐situ Remediation of Hydrogen Fluoride During a Detonation Event

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Abstract
Hydrogen fluoride (HF) is a known product from the combustion or detonation of explosives formulated with fluoropolymer binder systems. This presents the user with elevated risk levels during unintended combustion events or detonations in confined situations. In an effort to remediate the production of HF, calcium disilicide (CaSi2) was added to explosive formulations and the amount of HF formed was monitored. Viton A/calcium disilicide mixtures were made and the thermal decomposition characteristics studied using thermal gravimetric/differential thermal analysis (TG/DTA). The activation energy ranged from 145–190 kJ mol−1, indicative of CF scission in the Viton A binder prior to calcium fluoride formation. An energetic formulation was prepared which consisted of approximately a 5/3 mass ratio of Viton A/CaSi2. Combustion calorimetry in oxygen and air, and subsequent analysis of the residues using X‐ray diffraction (XRD) showed evidence of calcium fluoride (CaF2) formation. The decrease in HF formation was determined by trapping off gases and subsequent analysis in anion exchange chromatography of combustion and detonation products. Upon introduction of calcium disilicide into the formulation, a small decrease in HF formation was observed along with appearance of calcium fluoride and free Si in the residue. Such products are consistent with the mechanism following a general decomposition path of 2F−+CaSi2→CaF2+2Si. Under detonation conditions, the decomposition path followed nearly the same route with a net ca. 30 % decrease in HF formation, but with a portion of the silicon oxidizing slightly further to SiO2.