VIBRATION-CONTROLLED DRY POWDER DEPOSITION FOR MANUFACTURING OF SURROGATE ENERGETIC MATERIALS

Energetic materials are a special class of materials which are immensely useful across applications due to their high energy density. However, energetics present unique challenges in manufacturing, processing, and handling. Sensitivity depends on microstructural features (i.e., porosity) established during manufacturing processes, external stimulation (i.e., electrostatic discharge, shock), environmental conditions (i.e. humidity), etc. Improving control of microstructure with new, safe manufacturing techniques such as powder deposition could expand the capabilities of energetic materials and improve sensitivity. Industries such as pharmaceuticals and additive manufacturing routinely use vibration to control dispensing of fine powders, but this has not been applied often to energetics. This research uses a DC vibration mini motor and Luer-lock nozzle tips to investigate controlled dispensing of sugar, soda lime, and nylon powders as energetic surrogates or potential binders. Changes in powder flow due to powder characteristics (size, shape, density), orifice sizes (0.2-1.6 mm), nozzle geometry (tapered and blunt-end), and motor voltages (1-3.4V) were quantified with high-speed image data and novel image processing scripts. Free flowing powders (> 150 µm) formed natural bridges in nozzles 2-4x larger. Finer, more cohesive powders bridged across larger orifice diameters. Vibration was applied to toggle flow by disrupting bridging. Higher vibration voltages created erratic dispensing patterns, while lower motor voltages (< 2V) yielded smaller cone angles and cyclic behavior tied to the motor frequency. A mixture of sugar and nylon was dispensed, and partial segregation was observed over time. This research demonstrated the range of vibration-controlled deposition conditions applicable to energetic materials which are currently lacking in literature.