Thermal-Ignition and Combustion Behavior of Pyrotechnic Composition Containing Mechanically Activated Commercial Mg-Al Alloy

Abstract

The effect of mechanical activation of commercial Mg-Al on its thermally-initiated reactions with KClO₄ under air atmosphere was investigated. Modifications of structure and morphology of Mg-Al during milling were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Thermogravimetry–differential scanning calorimetry (TG-DSC) analysis and light emission measurement combined with a test of combustion products indicated that KClO₄/Mg-Al mixtures containing milled Mg-Al had lower ignition temperature, faster combustion rates, and more complete combustion than the mixture containing commercial Mg-Al, especially when milling time was within 4 h–12 h. This was ascribed to decrease in particle size and appearance of nano-structured surface for milled Mg-Al. On the other hand, for the mechanically activated Mg-Al, prolonging milling time up to 16 h not only caused a significant decrease in heat release during ignition reaction, but also caused decreases in combustion rates and light emission intensity of the pyrotechnic mixture. Air-passivation and more obvious preferential oxidation of Mg component in the long-time milled Mg-Al were suggested as reasons for deterioration in combustion property of the pyrotechnic composition.

Keywords:

• Combustion reaction
• Mechanical activation
• Mg-Al alloy
• Particle size effect

Additional information

Funding

The authors would like to thank the support of the Science and Technology Foundation of CAEP under Grant No. 2013B0302052 and the Open Foundation of Joint Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology and Research Center of Laser Fusion, CAEP under Grant No. 12zxjk01.