Enhancement of energy deposition in pulsed wire discharge for synthesis of nanosized powders

Nanosized particles, less than 100 nm in diameter, have been successfully synthesized by pulsed wire discharge (PWD). The powders prepared by PWD contained submicron-sized particles, in the range of 0.1 /spl mu/m-1 /spl mu/m in diameter. The existence of submicron-sized particles is attributed to liquid droplets due to lower energy deposition in the wire than vaporization energy of the whole wire. The effect of the energy deposition on particle size distribution was investigated with the copper powders prepared in the atmospheric gas of nitrogen. The energies deposited in the wire were estimated by measuring the currents and voltages for various discharge conditions. Under the conditions of high atmospheric pressure and fast-current rise, the energy deposition was significantly enhanced. The energy deposition mainly affects the quantity of submicron-sized particles that originates from unvaporized liquid droplets rather than the average particle size of nanosized powders.