Production of fine powder by spark discharge

Abstract

As an application of electrode erosion by electric discharge, a new method was developed in which fine powder was produced by the spark discharge.When metal pellets are dipped into the liquid medium, the contact points of each pellets form the spark points. The pellets repel momentarilly each other by the impulse of spark discharge, and maintain its steady spark discharge by shifting the contact points and inhibiting the conversion to arc discharge. Thus fine powder is produced at spark points.In spark discharge circuit, electrostatic capacity of condenser is set as small as possible, and enhances the condenser energy by higher charge voltage. In addition, the discharge voltage is brought to be higher by quenched spark gap.The powder quantity is increased with the higher discharge voltage (10-40 kV) and its particle size becomes smaller with increase of frequency (230-610 kHz). Discharge condition has been investigated for producing fine powder (0.05-5μm) from aluminum, copper and iron materials. Finally the theoretical description has been given with regard to the mechanism of producing the fine powder at spark points.