Unraveling the Impact of Heat- or Moist-Aging on the Combustion Heat, Ignition Features, Multistep Thermal Decomposition, and Kinetics of a Magnesium-Based Energetic Composite

Abstract

ABSTRACT In this work, a Mg-based energetic composites, commonly known as pyrotechnic tracer composition (Mg-PC), was successfully fabricated by a mechanical milling method. The influence of the impact of artificial heat- or moist-aging on the combustion heat, ignition characteristics, and the thermal decomposition behavior of the as-prepared composite were investigated. Results show that the total energy output has decreased by 16% and 51% for the heat- and moist-aged samples, respectively. Microcalorimetric studies revealed shorter induction times and higher heat flow magnitudes for the different aged samples. Compared with the unaged composition, the ignition time of heat- and moist-aged samples are distinctly increased by 2.2 and 14.3 times, respectively. The thermogravimetric analysis demonstrated that humidity and thermal agings have a catalytic effect and accelerate the decomposition reaction, reducing the onset temperature decomposition by about 4–6°C after aging. The kinetic deconvolution analysis (KDA) indicated a multistep reaction comprising the resin decomposition, partial decomposition of the oxidizer, and the combustion of the Mg-PC. The activation energy of the first two decomposition steps was lower than that of the as-prepared mixture. Furthermore, the combustion process, corresponding to the third step exhibited slightly higher activation energy compared to the unaged formulation and is assigned to the fuel oxidation and the pre-decomposition of the oxidizer under heat- or moist-aging.