RDX基PBX在高温条件下热损伤表征试验研究

Experimental study on thermal damage characterization of RDX-based PBX after high-temperature treatment

炸药热损伤特征及演化行为对装药安全性具有重要影响。为探究高聚物黏结剂炸药(Polymer Binder Explosive,PBX)在不同温度载荷下的内部损伤和演化行为,对无约束状态下炸药进行烤燃试验,使用分析天平监测炸药的质量变化,并采用显微镜和扫描电子显微镜等技术对炸药样品的表面和内部损伤进行表征。结果表明:温度越高,炸药的质量损失越大且损失速率越快;加热过程中黏结剂先发生熔化,随着加热时间变长和温度升高,黏结剂熔化程度增大,流动性增强,气体从炸药表面孔洞内逸出,孔洞增多且尺寸变大;温度越高炸药内部出现的孔隙越多,孔隙尺寸越大,孔隙主要是由于气体从试样内部逸出形成;炸药内部比表面积变化趋势为上升—下降—上升,其变化趋势受到化学反应速率和黏结剂的流动及损失影响。黏结剂材料的热稳定性是影响炸药热损伤演化行为的重要因素。

The thermal damaged features and evolution behaviors of High Explosives(HEs)has an important effect on their safety.To investigate the internal damage and evolution behavior of RDX(1,3,5-trinitro-1,3,5-triazinane)-based Polymer Binder Explosive(PBX)under different temperature loads(unheated,140℃,160℃,180℃ for 40 h),an unconstrained cook-off experiment was designed.Throughout the experiment,the mass change of the explosives was monitored through balance analysis to determine the law of mass loss under high-temperature loading conditions.Optical microscopy and scanning electron microscopy were used to observe the surface of the explosive and obtain information on its damage evolution.Micro-CT was used to characterize the internal structural damage of the explosive.Results show that the higher the loading temperature,the greater the mass loss and mass loss rate of the explosive.At 140℃,the binder melts,and with increasing temperature,the degree of binder melting increases while the fluidity is enhanced.At 180℃,the binder and RDX crystals become mixed,such that the boundary can not be distinguished between the two.Gas escaped from the holes on the surface of the explosive,and the binder formed a bubble-like structure.As temperature increases,the number and size of surface holes in the explosive also increase.The amount and size of voids inside the explosive increase with increasing temperature,which are largely formed by gas escaping from the interior of the sample.The variance law of the specific surface area inside the explosive changes from up-down-up and is influenced by the chemical reaction rate and the flow and loss of the binder.The thermal stability of binder materials is an important factor affecting the evolution behaviour of thermal damage of explosives.Therefore,improving the thermal stability of binder materials is particularly important for reducing the thermal sensitivity of explosive materials.