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Accelerated ageing of SR‐562 pyrotechnic composition and investigation of its thermo kinetic parameters

Pyrotechnics are used to produce some special effects in various military and civilian applications. High temperatures and elevated humidity levels influence the thermal decomposition and kinetic behaviour of pyrotechnics. The present work describes the effect of ageing on SR‐562 military pyrotechnic composition. The composition contains magnesium, sodium nitrate and calcium oxalate and it is used as a flare. The composition was aged for 30 days at a temperature of 70 °C and relative humidity (RH) of 70%. The experimental results show noteworthy variations in the thermal cum kinetic behaviour as well as in the morphology of the aged composition. Activation energy of the aged composition decreased to 189 kJ mol−1 from 239 kJ mol−1 for the fresh composition. Thermal decomposition temperature was found to increase by 51 °C after the ageing. X‐ray diffraction results confirm the presence of magnesium hydroxide in the aged composition showing that some of the magnesium reacted with water vapours at high temperatures. Some micro sized cracks have been seen in the scanning electron microscopy micrographs of the aged composition. Copyright © 2016 John Wiley & Sons, Ltd.