Continuous spheroidization strategy for explosives with micro/nano hierarchical structure by coupling microfluidics and spray drying

Abstract The spheroidization of explosives with micro/nano hierarchical structure is a feasible and efficient way to meet the requirements of energy and safety. In order to achieve the expectation, a microfluidic strategy consisting of a spheroidization model and verification experiments was proposed. The model states a possible spheroidization process and three spheroidization types by theoretical analysis. Furthermore, a continuous microfluidic platform was established for the verification experiments, which is consisting of a combinatorial microfluidic module and a spray-drying module. Here we used HNS (2,2′,4,4′,6,6′hexanitrostilbene) to verify the applicability of the strategy. The spheroidization process was verified by deconstructing HNS microspheres and adjusting the internal-outside pressure at the microscale. The spheroidization types were verified by tuning flow rate ratios of the solvent and antisolvent. It was found that the model is quite applicable for the spheroidization of micro/nano hierarchical structure by microfluidics. According to the detonation test, it was found the HNS microspheres have similar firing sensitivity to nano HNS under short-pulse shock wave, which means the better fluidity and higher bulk density can be realized while retaining the firing sensitivity. This study demonstrates an efficient, safe strategy to realize the high-quality spheroidization and continuous preparation of explosives with micro/nano hierarchical structure.