The auto-ignition behaviors of HMX/NC/NG stimulated by heating in a rapid compression machine

Abstract

In this work, we have for the first time, applied a rapid compression machine (RCM) to generate initial uniformly high temperature environment to investigate the auto-ignition behaviors of solid energetic material (HMX/NC/NG). Pressure evolution recording and high speed visualization were synchronized to reveal the response of energetic material to thermal stimulus in a time scale of the order of 100 ms. Results show that at sufficiently high end of compression (EOC) pressure and temperature, auto-ignition of solid energetic material is observed after certain period of induction time upon EOC. The ignition delay time defined by the first flame spot observation from high speed imaging (IDTI) is smaller than defined by the maximum pressure rise rate instant (IDTP). However, both IDTI and IDTP decrease with the increase of EOC pressure and temperature. In addition, the burning duration also decreases, indicating a faster burning rate. By tuning the EOC pressure and temperature, the critical thermodynamic condition that separates the auto-ignition region and the non-ignition regime is obtained. The present method of thermal stimulus generation is believed to provide a new approach for evaluating the thermal stability of energetic materials, beyond the literature on cook-off test approaches.