Analysis of Vibration‐enabled Dynamic Dispensing of Surrogate Energetic Powders

ABSTRACT Energetic materials have uniquely high energy densities and rapid release rates that provide solutions to a wide range of engineering problems, such as propulsion and demolition. The sensitivity of energetics is dependent on many factors, including microstructure and sources of initiation (i.e., mechanical insult, thermal, and electrostatic discharge). Vibration‐enabled powder deposition, which has been used in the pharmaceutical industry, can be used to achieve precise measurement and placement of raw energetic powders to control sensitivity. However, the compatibility of energetic powders with powder deposition techniques has not been deeply studied. In this research, particle bridging over a nozzle orifice was characterized for surrogates such as sugar, nylon, and soda lime microspheres with sizes ranging from 10 to 300 µm. Luer‐lock nozzles with orifice sizes from 0.2 to 1.6 mm were used, and vibration was applied at 100–300 Hz. Controllable deposition of the powders was possible when orifice‐to‐powder diameter ratios (ID/d90) were 2–4 for larger powders and ID/d90>4 for fine powders. The dynamic powder deposition process was analyzed using high‐speed videos and custom scripts to understand the cone angle and particle dispersion. Furthermore, repeatable deposition of a target dose of 20 mg was achieved for each material at low voltages. Finally, a custom script was used to track the change in nylon particle content over time in a sugar/nylon mixture. The analysis showed that the nylon content was not solely influenced by particle segregation, but also by nylon agglomeration with the sugar. This research presents a path for controlled vibration‐enabled deposition of energetic powders and mixtures.