Submicron Potassium Perchlorate: a Key Component to Reach Detonation in Binary Mixtures with Titanium Hydride

The pyrotechnic compositions made up of potassium perchlorate (KClO4) and titanium hydride (TiH2), known as THKP, have a fast deflagration velocity (similar to 500 m/s), along with low sensitivity and high stability. In this research, a new kind of THKP was formulated from a submicron powder of KClO4 (50-400 nm) prepared by the Spray Flash-Evaporation (SFE) process. The use of fine KClO4 not only ensures better oxidation of TiH2, but also leads to a transition to detonation in the THKP. This transition is observed in loose powders placed in small diameter tubes (3 mm). The distance of transition is relatively short (17-22 mm) and increases with the KClO4 content of the THKP mixture. The detonation front propagates steadily, at a velocity of similar to 1250 m/s in THKP powders with 86 % of porosity. The shockwave velocity varies little with the perchlorate content in the domain of composition studied (55-74 wt.% of KClO4). Conversely, in the classical THKP mixtures prepared from micron-sized KClO4 and tested in the same conditions, no transition to detonation is observed; the combustion slows down and eventually stops. Finally, owing to their high sensitivity thresholds to impact (S-Imp.>= 44.7 J), friction (S-Fr.>= 192 N), and electrostatic discharge (S-ESD >= 34.7 mJ), THKP mixtures prepared from submicron KClO4 can be classified as low-sensitivity primary explosives.

Automated summary

The research introduced a new type of pyrotechnic composition THKP, formulated from submicron KClO4 and TiH2, with fast deflagration velocity and high stability. The transition to detonation was observed in THKP, whereas conventional THKP prepared from micron-sized KClO4 did not exhibit this transition.