Abstract
Ammonium perchlorate (AP) is one of the most commonly used energetic oxidizers in solid propellants, providing strength and playing a crucial role in customizing propellant formulations. Preparing ultrafine AP with controllable particle size and crystal shape is essential for improving propellant formulations, especially for adjusting the burning rate. Traditional preparation methods face complicated steps, high energy consumption, and limited ability to control the quality. Therefore, this study developed an ultrasound-assisted antisolvent crystallization process as an alternative for producing ultrafine AP particles. The solubilities of AP in various organic solvents were determined, and the effect of solvent/antisolvent combination and solvent-to-antisolvent ratio was first screened to meet the goal of acceptable crystallization recovery. Then, several ultrasound-assisted antisolvent crystallization experiments were performed with the screened combination and ratio. By selecting the appropriate solvent/antisolvent system and applying sonication during the crystallization step, ultrafine AP particles with a mean size of 3.8 μm, a recovery of 83%, and a quasi-spherical crystal shape were successfully produced. In addition, the crystal structure, spectrometric properties, thermal properties, and decomposition behavior of the ultrasound-assisted recrystallized AP were compared with those of the unprocessed and the recrystallized AP without sonication. These results indicate that ultrasound-assisted antisolvent crystallization offers an efficient approach to designing ultrafine AP particles and has the potential for preparing other energetic materials.
