Patent ID: 7520914

Claim:
A process for the manufacture of a nickel powder, wherein nickel powder particles are oxidized on their surface by means of a transferred arc plasma system, the process comprising the steps of: (a) continuously providing nickel in a transferred arc plasma reactor; (b) striking an arc between the nickel and a non-consumable electrode in a straight polarity configuration to generate a plasma gas having a temperature sufficiently high to vaporize the nickel and form a vapor thereof; (c) injecting a diluting gas heated to a temperature of at least 1000 K into the plasma reactor; (d) transporting the vapor by means of a carrier gas comprising the plasma gas and the diluting gas into a thermostatisized tube wherein the temperature is controlled at between 1000 and 1500° C. to control particle growth and crystallization during passage of the carrier gas through the tube; (e) introducing the carrier gas with entrained nickel particles into a quench tube with injection of a cooling fluid directly into the carrier gas through one or more cooling fluid inlets along the quench tube; (f) introducing oxygen in an amount sufficient to effect surface oxidation of the entrained nickel powder particles as an additive to the cooling fluid supplied to a first of the one or more cooling fluid inlets; and (g) separating the nickel powder from the carrier gas and the cooling fluid.