Nanosize Powders of Zinc Oxide Produced by Electrical Explosion of Zinc Wires

Nanosize powders of zinc oxide are of potential application in making better varistors for metal oxide arresters. Production of nanosize powders of zinc oxide by electrical explosion of zinc wires in oxygen was experimentally investigated. A pulse current generator was constructed for exploding the wire. The generator is composed of a spark gap switch triggered at a voltage from 10 kV to 40 kV and a capacitor of 2 muF charged to a few tens kilovolts depending on the mass of the wire to be exploded. A discharge chamber for housing the wire was evacuated to a gas pressure below 0.1 torr and then filled with oxygen at pressure in range of 100 torr ~760 torr. One Zn wire (0.2-0.5 mm in diameter, 50-100 mm in length) as the load of the pulse current generator was located in the center of the chamber. A mechanical system was designed to feed the wires without opening the chamber. After 10 wires were exploded, the powders were collected by the evacuation through membrane filter with pore size of 100 nm in diameter. The powders were analyzed by X-ray diffraction, transmission electron microscopy, BET surface area analyzer and laser particle size analyzer. The size of the most powders is found to be smaller than 100 nm.