Effect of Pulsed Current and Mold Material for Pulsed Current Sintering.

Abstract

The effect of a pulsed current on heating in a pulsed current sintering (PCS) was examined. When a graphite mold was used for the PCS, the heating rate of the mold did not depend on a frequency of a pulsed current. The heating rate of graphite applying pulsed current was larger than that of graphite applying direct current, because of the difference of the input of energy between pulsed current and direct current.The heating rate of the mold in a PCS was determined by a mold material. The hard metal with free carbon was heated more quickly than a usual hard metal in the PCS. Moreover, the cast iron including the precipitation of carbon was obtained higher heating rate by applying pulsed current. The heating rate of cast iron was almost unchanged by the morphology of the carbon, such as nodular graphite cast iron and gray cast iron.The metal mold including carbon is suitable for the near net forming of the powder in the PCS because of its machinability.