Stability of pyrotechnic composition in flame detonator exposed to severe thermal stimulus

Abstract

The stability of pyrotechnic composition used in flame detonator was studied at severe temperatures (–70―130 °C) for 5 d. For single N-LTNR(normal lead styphnate), camera was used to observe the shape and colour of N-LTNR in the DSC(differential scanning calorimetry) furnace during continuous heating and cooling processes. Based on the DSC-TGA(thermogravimetric analysis) results, it can be seen that when the temperature exceeded 110 °C, N-LTNR lost its crystal water, making the energetic material become darker in colour, smaller in dimension, lager in volume and lighter in weight(3.416%); when the temperature was below −40 °C, the phenomenon of sample broking, jumping and cracking happened. For the N-LTNR and Pb(N₃)₂(lead azide) double layers, the loss of N-LTNR’s crystal water at the temperature higher than 110 °C caused the hydrolysis reaction of Pb(N₃)₂, and the purity of Pb(N₃)₂ measured after the temperature cycling decreased from 98.6% to 95.26%. For the flame detonator, the height and diameter of the flame detonator were measured and no apparent changes of them were found. The p-t(pressure-time) test shows that the peak pressure was decreased by 3.9%. Therefore, the operating temperature of this flame detonator should be limited to −40–110 °C.

Keywords

Normal lead styphnate / Lead azide / Flame detonator / Stability

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