Differences of thermal decomposition behaviors and combustion properties between CL-20-based propellants and HMX-based solid propellants

Abstract

Differences of thermal decomposition characteristics and combustion properties between CL-20-based propellants and HMX-based propellants were researched by combination of theory and practice. Burning rates and burning rate pressure exponents of CL-20-based propellants were much higher than those of HMX-based propellants, when contents and particle sizes of CL-20 and HMX were identical. The thermal decomposition of CL-20 and CL-20-based propellants was systematically studied by comparison of HMX and HMX-based propellants. HMX melted firstly at 198.53 °C and then decomposed violently at 284.3 °C, while CL-20 only decomposed violently at 246.9 °C without any melting peak, and the heat released from decomposition of CL-20 was much higher than that of HMX. Thermal decomposition of CL-20 or HMX could be greatly enhanced by GAP. CL-20 could accelerate the high-temperature decomposition of AP, whereas the decomposition of HMX was greatly enhanced by AP. Mole ratio of [NO2]/[N2O] in decomposition gas products of CL-20 was 3.07, whereas the result for HMX was 0.43. More oxidative gases were generated for CL-20 or CL-20-based propellants. Molar reaction heat in luminescent flame zone and dark zone for CL-20-based propellants was much higher than that for HMX-based propellants, resulting in a higher burning rate for CL-20-based propellants. Value of [NO2]/[N2O] for gas-phase products of thermal decomposition of CL-20/ammonium perchlorate (AP) mixed system was also much higher than of HMX/AP mixed system, resulting in more oxidative gases, such as NO2, involved in the thermal decomposition and combustion of CL-20-based propellants with ammonium perchlorate, further leading to higher burning rates of CL-20-based propellants.