The Auto-Ignition Behaviors and Thermal Safety of the Composite Modified Double Base Propellants under Rapid Heating

The safety issue of energetic materials (EMs) such as propellants or explosives has been a high concern. When EMs are subjected to rapid thermal stimulus, they will ignite or explode, which may cause personal injury and property loss. Studies on auto-ignition behaviors and thermal safety of EMs under rapid thermal stimulation provide important guidelines for EMs in their production, transportation, storage, and application. In this work, auto-ignition experiments of the composite modified double base (CMDB) propellants, which include 1,1-diamino-2,2-dinitroethylene (FOX-7) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) mixtures under high initial temperature condition, have been conducted by using a rapid compression machine (RCM). The temperature rise rate can reach up to 2×10⁴ K/s. Pressure evolution recording and high speed-visualization were synchronized to reveal the auto-ignition behaviors of CMDB samples. Results show that the end of compression (EOC) temperature and pressure have a significant impact on the ignition delay time (IDT). The IDT increases with a decrease in temperature and pressure. In addition, through tuning the EOC temperature and pressure, the critical condition that separates the ignition region and non-ignition region is obtained. The critical ignition temperature of CMDB decreases with an increase in pressure. When the pressure is higher than 2.0 MPa, the critical temperature is about 650 K.