Preparation of silver nanopowder by thermal plasma

Nano-sized silver powder was prepared from micro-sized silver powder by thermal plasma processing. As a process parameter, feeding rate of raw material was controlled by the flow rate of the carrier gas. To study the effect of the composition of plasma generation gas, He and H2 were mixed with Ar respectively. Most of prepared powder was collected on the quenching tube. Characteristics of the powders were analyzed using X-ray diffractometer (XRD), scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDS), light scattering particle size analyzer (PSA), and UV/Visible spectroscopy. Under Ar plasma, raw powder was not completely evaporated, forming a bimodal structure. By introducing the H2 gas, the evaporation of silver powder was enhanced. With increasing H2, raw powder was fully evaporated and prepared powder was evenly distributed with a mean size below 100 nm.