<p dir="ltr">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.</p>

<p>Raman spectroscopy is a molecular spectroscopy technique that uses monochromatic light to provide a fingerprint to identify structural components and chemical composition. Depending on the changes in the unit-cell parameters and volume under the application of stress and temperature, the Raman spectrum undergoes changes in the wavenumber of Raman-active modes that allow identification of sample characteristics. Due to the various advantage of mechanical Raman spectroscopy (MRS), the use of this technique in the characterization and modeling of chemical changes under stress and temperature have gained popularity. </p> <p> Quantitative information regarding the local behavior of interfaces in an inhomogeneous material during shock loading is limited due to challenges associated with time and spatial resolution. Recently, we have extended the use of MRS to high-strain rate experiments to capture the local thermomechanical response of mock energetic material and obtain material properties during shock wave propagation. This was achieved by developing a novel method for <i>in‑situ</i> measurement of the thermo‑mechanical response from mock energetic materials in a time‑resolved manner with 5 ns resolution providing an estimation on local pressure, temperature, strain rate, and local shock viscosity. The results show the solid to liquid phase transition of sucrose under shock compression. The viscous behavior of the binder was also characterized through measurement of shock viscosity at strain rates higher than 10⁶/s using microsphere impact experiments.</p> <p> This technique was further extended to perform Raman spectral imaging over a microscale domain of the sample with a nano-second resolution. This was achieved by developing a laser-array Raman spectral imaging technique where simultaneous deconvolution of Raman spectra over the sample domain was achieved and Raman spectral image was reconstructed on post-processing. We developed a Raman spectral imaging system using a laser array and analysis was performed over the interface of sucrose crystals bonded using an epoxy binder. This study provides the Raman spectra over the microstructure domain which enabled the detection of localized melting under shock compression. The distribution of shock pressure and temperature over the microstructure was obtained using mechanical Raman analysis. The study shows the effects of an actual interface on the propagation of shock waves where a higher dissipation of shock energy was observed compared to an ideal interface. This increase in shock dissipation is accompanied by a decrease in both the maximum temperature, as well as the maximum pressure within the microstructure during shock wave propagation.</p>