| Abstrakt: |
The temperature-impact safety correlation of a cyclotetramethylene tetranitramine (HMX) based polymer-bonded explosive (PBX) was investigated. Matrix of tests was determined by projectile velocities in the range of 160 m/s-370 m/s and five temperature cases of 28 °C (room temperature), 75 °C, 105 °C, 160 °C, and 195 °C. The safety performance under thermal-impact combined environment was evaluated by high speed camera and air over-pressure gauges. The samples before and after impact were compared by the scanning electron microscope. The mechanical performance and thermal decomposition under different temperatures were also studied by mechanics machine and the thermo gravimetric analysis technique. The phase transition of PBX-2 is investigated by XRD spectrograph. The results show that the reaction threshold of unheated explosive is between 263.5 m/s and 269.9 m/s. While heated to 75 °C and 105 °C, the values are increased to 316 m/s-367 m/s and 286 m/s-298.3 m/s, respectively. However, the threshold is less than 176 m/s at 160 °C and the threshold at 195 °C is even lower, which is less than 166.7 m/s. According to the temperature histories, the pictures of wreckages, the over-pressures, the mechanical performance, the thermal decomposition, and phase transition properties, some conclusions can be drawn. First of all, compared with unheated case, the impact safety of PBX-2 is improved at both 75 °C and 105 °C by a softened, easy-flowing, and energy absorbing mechanical properties. Secondly, at 160 °C, the impact safety becomes worse due to the thermal decomposition. Thirdly, when the temperature reaches or exceeds the β → δ phase transition range, the impact safety of PBX-2 becomes significantly worse. [ABSTRACT FROM AUTHOR] |
