Combustion efficiency and pyrochemical properties of micron-sized metal particles as the components of modified double-base propellant

The combustion efficiency of metallized propellants are investigated and compared to the corresponding blank propellant in order to evaluate the actual effect of the metals in solid rocket applications. The image analysis coupled with energy dispersive spectrometry (EDS) analysis on a scanning electron microscope (SEM) and quantitative X-ray diffraction analysis were applied to the characterization of the original metal particles such as aluminum (Al), magnesium (Mg), boron (B), nickel (Ni), and Mg–Al alloy (Mg/Al) and their condensed combustion products. Under the explored operating conditions, the results confirm that the metallized propellants show heterogeneous diffusing flame, with significant change in pressure sensitivity, and larger aggregation/agglomeration phenomena in combustion products than that of the blank propellant. Besides, the chemical reactions in condensed phase and gas phase which control the burning process and combustion efficiency of the double-base propellant containing different metal particles were systematically investigated and descriptions of the detailed reaction mechanisms from solid phase to liquid phase or to gas phase are also included. It was indicated that the combustion efficiency is favored by the activity and melting points of the metals.