Preparation and characterization of energetic materials coated superfine aluminum particles

Abstract This work is devoted to protect the activity of aluminum in solid rocket propellants by means of solvent/non-solvent method in which nitrocellulose (NC) and Double-11 (shortened form of double-base gun propellant, model 11) have been used as coating materials. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to characterize the morphology of coated Al particles. Other characterization data of coated and uncoated Al particles, such as infrared absorption spectrum, laser particle size analysis and the active aluminum content were also studied. The thermal behavior of pure and coated aluminum samples have also been studied by simultaneous thermogravimetry–differential thermal analysis (TG–DTA) and differential scanning calorimetry (DSC). The results indicated that: superfine aluminum particles could be effectively coated with nitrocellulose and Double-11 through a solvent/non-solvent method. The energetic composite particles have core-shell structures and the thickness of the coating film is about 20–50 nm. The active aluminum content of different coated samples was measured by means of oxidation–reduction titration method. The results showed that after being stored in room temperature and under 50% humidity condition for about 4months the active aluminum content of coated Al particles decreased from 99.8 to 95.8% (NC coating) and 99.2% (Double-11 coating) respectively. Double-11 coating layer had a much better protective effect. The TG–DTA and DSC results showed that the energy amount and energy release rate of NC coated and Double-11 coated Al particles were larger than those of the raw Al particles. Double-11 coated Al particles have more significant catalytic effect on the thermal decomposition characters of AP than that of NC coated Al particles. These features accorded with the energy release characteristics of solid propellant.