UC San Diego

The process of spark erosion employs an electric discharge to break down bulk materials into fine powders and has been developed to produce nanostructured powders of metallic, ceramic, and semiconducting materials. This work demonstrates the optimization of charge morphology, energy parameters, and liquid dielectric of a “shaker-pot” spark erosion process to produce maximum yields and size-specific nanopowders. Nanopowders were assessed using x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission scanning electron microscopy (t-SEM), dynamic light scattering (DLS), and a new multispectral advanced nanoparticle tracking analysis (MANTA) technique. Additional efforts were taken to evaluate the new MANTA technique and its performance capabilities and limitations for application in fast and accurate particle size analysis. A single-spark apparatus was also constructed to evaluate the discharge mechanics relevant to nanoparticle formation. High-speed imaging and spectroscopy were used to investigate the characteristic plasma arc, shock wave, and plume evolution in a submerged capacitive discharge system. The effects of varying both the capacitance and liquid dielectric (liquid nitrogen/ethanol) are evaluated. Discharge features such as plume temperature and time are discussed with respect to previous findings and active particle formation mechanisms that influence size-tunability of the spark erosion technique.