Explosive Powder Preparation And Characterization Based On Spray Drying Technology

HMX and RDX are the most representative elemental explosive in nitramine explosives.They are widely used in mixing explosive, warhead charge and Booster. The performance ofelemental explosive is greatly influenced by the characteristics of morphology. The explosivemorphology can be effectively improved by the spray drying method. Therefore, it isimportant to study the spray drying method for improving the explosive performance.The mechanism of the influence on the crystal morphology has been studied from thepoint of evaporation crystallization and spray drying theory using spray drying technology.The influence of factors, such as solvent type, entrance temperature, precursor solutionconcentration, spraying gas flow rate and feed rate on the RDX/HMX particles’ morphologywere investigated in the process of spray drying.The optimum conditions of preparing spherical RDX by the single factor experimentwere acetone as the solvent, feed rate of1.5mL·min-1, pumping flow of40m3·h-1, entrancetemperature of60℃, spraying gas flow rate of357L·h-1, RDX mass fraction of1.9%.Scanning Electron Microscope (SEM) was employed to characterize the samples. The impactsensitivity and thermal decomposition properties of the samples were also measured andanalyzed. The results show that the spherical RDX particles range from0.5μm to5μm in sizeand the particle surface has fewer defects. Compared the raw RDX, the thermaldecomposition apparent activation energy(E) and the thermal explosion criticaltemperature(Tb) of the spherical RDX decrease3.99kJ/mol and1.19℃, but the impactsensitivity of the spherical RDX is decreased obviously that the drop height rises from19.98cm to54.70cm.The spray drying process of preparing fewer defect and low sensitivity spherical micronHMX was obtained by orthogonal experiments. The optimum conditions of orthogonalexperiments were acetone as the solvent, entrance temperature of70℃, feed rate of7.5mL·min-1, spraying gas flow rate of357L·h-1, precursor concentration of1.5%. The spherical HMX was measured and analyzed. The results show that the spherical HMX particles sizerange from0.5μm to2μm and the crystal is βtype same as raw HMX. Compared the rawHMX, the apparent activation energy of thermal decomposition of the spherical HMXreduced by21.96kJ·mol-1. But the impact sensitivity of the spherical HMX is decreasedobviously that the drop height increase156.1%over raw HMX.