Preparation of a superfine RDX/Al composite as an energetic material by mechanical ball-milling method and the study of its thermal properties

To research the influence of aluminum (Al) on the decomposition of 1,3,5-trimethylene trinitramine (RDX), a type of superfine RDX/Al composite as an energetic material with a mass ratio of 70/30 was successfully prepared by mechanical ball-milling method. The morphology and structure of the superfine RDX/Al composite were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The thermal decomposition properties were analyzed by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and thermal-infrared spectrometry (DSC-FTIR) online. The results showed that the as-prepared material was a type of a novel superfine composite with the superfine RDX particles coated on the surface of Al flakes. XPS analysis indicated that a new Al–N bond was formed in the superfine RDX/Al composite and both physical and chemical absorptions existed between RDX and Al at the same time. The thermal decomposition temperature of RDX in the superfine RDX/Al composite had a shift of about 50 °C towards the lower temperature range compared with that of the neat superfine RDX when tested at four heating rates of 5, 15, 25 and 35 °C min(−1). Its activation energy value also decreased to 70.8 kJ mol(−1) compared with that of the neat superfine RDX (119.6 kJ mol(−1)). Moreover, thermal sensitivity of the superfine RDX/Al composite increased. DSC-FTIR analysis showed that the main decomposition products of the superfine RDX/Al composite were N(2)O and CO(2) with nearly no NO and NO(2) detected. The formation of Al–N bond and reactive Al atoms are the main reasons for the notably advanced decomposition of RDX in the superfine RDX/Al composite.