Propellants Explosives Pyrotechnics, Vol.44, No.7, 908-914, 2019
Milling of Energetic Crystals with the LabRAM
Processing energetic materials with the LabRAM acoustic mixer has been widely published; however, using it as a vibratory mill has only recently been explored. The size reduction of energetic crystals remains a tremendous processing challenge as it is often time and energy intensive. The LabRAM has the potential to reduce the time and energy required for milling through the use of low frequency waves. In this study, three distinct materials were selected to determine the effects of milling with the LabRAM. Ammonium perchlorate (AP), sodium periodate (NaIO4), and nitroguanidine (NQ) were chosen as their starting crystal morphologies are spherical, irregular, and needle-like, respectively. The three materials were analyzed by laser particle analysis and scanning electron microscopy (SEM) to determine the average particle size and any morphology changes that may occur while milling. The average particle size, D-50, of the starting materials, AP, NaIO4, and NQ were 253 mu m, 415 mu m, and 60 mu m, respectively. The D-50 after only 15 minutes of continuous milling for AP, NaIO4, and NQ was 7.01 mu m, 2.92 mu m, and 22.90 mu m, respectively. This study focuses on the feasibility of safely dry milling micron-size energetic crystals on the LabRAM acoustic mixer, while optimizing milling parameters for effective size reduction.