Thermal properties of decomposition and explosion for CL-20 and CL-20/n-Al

Nano-sized aluminum powders (n-Al) are usually added to high energy explosives and propellants o promote their detonation and combustion performance. From the perspective of thermal safety, this work focused on the thermal decomposition and explosion properties of CL-20 in the absence and presence of 30 wt% n-Al (CL-20/n-Al). The results of DSC experiments showed that the activation energy (Eα) of thermal decomposition of CL-20 slightly decreased upon addition of n-Al, implying that n-Al exhibited a certain degree of catalytic effect on the thermal decomposition process of CL-20, but the catalytic activity is quite low. By nonlinear multivariate regression method, the kinetic model for the thermal decomposition of CL-20 and CL-20/n-Al was determined as n-th order reaction with autocatalysis, and both the reaction order (n) and autocatalytic kinetic rate constant (kcat) of CL-20 were found to be lower than those of CL-20/n-Al, indicating that the complexity of the decomposition reaction system and autocatalytic ability of CL-20 during thermal decomposition increased upon addition of n-Al. By the deflagration point tests, the Five-Second explosion temperature (Tb) of CL-20 and CL-20/n-Al was determined to be 277.7°C and 282.3°C, respectively. Moreover, the activation energy (Eb) of thermal explosion of CL-20 and CL-20/n-Al were calculated as 159.98 kJ mol−1 and 100.7 kJ mol−1, respectively. From the more than one-third reduction of Eb value, it can be concluded that the thermal sensitivity of CL-20 explosive could be remarkably decreased by adding n-Al, especially under the low-temperature condition.