Combustion Properties of Metal Particles as Components of Modified Double-Base Propellants

Metal particles such as aluminum (Al), magnesium (Mg), boron (B) and nickel (Ni), as well as Mg/Al alloy (Mg/Al3/4) are currently the most widely used ingredients in modified double-base propellants. In this contribution, the combustion properties of the metal species are studied by means of the high-speed photography technique and the non-contact wavelet-based measurement of flame temperature distribution. The combustion process of the Al, Mg and Mg/Al samples shows both gas phase reaction and surface oxidation, which yield volatile and nonvolatile products, corresponding to the oxide and suboxide respectively. However, the combustion of B and Ni shows only gas phase reaction, due to their high melting point as well as high enthalpy of vaporization. In addition to the experiments, a hypothetical combustion model has been proposed to clarify the combustion characteristics of metal species in modified double-base propellants.