Pulsed high energy synthesis of fine metal powders

Details Pulsed high energy synthesis of fine metal powders Pulsed high energy synthesis of fine metal powders

1997-07-25

1999-08-10

Paschall, Mark

Electric heating

Metal heating

By arc

219 7616, 21912152, 21912143, 75338, 75346, 427569, 427565, B23K 1000

Patent

active

059354615

ABSTRACT:
Repetitively pulsed plasma jets generated by a capillary arc discharge at high stagnation pressure (>15,000 psi) and high temperature (>10,000 K) are utilized to produce 0.1-10 .mu.m sized metal powders and decrease cost of production. The plasma jets impact and atomize melt materials to form the fine powders. The melt can originate from a conventional melt stream or from a pulsed arc between two electrodes. Gas streams used in conventional gas atomization are replaced with much higher momentum flux plasma jets. Delivering strong incident shocks aids in primary disintegration of the molten material. A series of short duration, high pressure plasma pulses fragment the molten material. The pulses introduce sharp velocity gradients in the molten material which disintegrates into fine particles. The plasma pulses have peak pressures of approximately one kilobar. The high pressures improve the efficiency of disintegration. High gas flow velocities and pressures are achieved without reduction in gas density. Repetitively pulsed plasma jets will produce powders with lower mean size and narrower size distribution than conventional atomization techniques.

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