Metco, Inc.

William A Vogts

Horace S Daley

An improvement in a plasma flame spraying apparatus, particularly one in which at least two gases form the plasma, which improvement comprises means associated with the plasma gas inlet, said means being time related to an increase in the current through the arc maintained in the plasma flame spray gun, said current and said means associated with the plasma gas inlet each independently being associated with a timing means whereby the full flow of a secondary gas through the nozzle of the gun and the electric arc established therein is substantially simultaneous with an establishment of a full current level through the electric arc through which said secondary gas passes; a fully automatic ignition system for a plasma gas flame spraying process whereby establishment of an optimum gas mixture for normal operation is time coordinated with respect to start-up of the current passing in the circuit of the electric arc in the gun, such that the current rise and rise of secondary gas flow through the gun occur within a relatively narrow time window established therefor; a means for insuring that initial establishment of the arc in the circuit of said gun is established automatically, which comprises a means for pulsing a high frequency current through the circuit containing the arc disposed in said gun for a time sufficient to establish an electric arc between electrodes in said circuit; a closed loop automatic start-up - shut-down electrical system for a plasma gun flame spraying process which enables close coordination of plasma gas through flow and current in mutual response to one another to preserve the life of the gun in which an electric arc is established through which said plasma gas passes, which comprises a means downstream of said gaseous inlet in said gun for determining the current through said circuit containing said electric arc, said means operative to compensatingly adjust a plasma gas flow rate to compensate for an increase in or decrease in the current through said circuit; a means of adjusting the current passing through an electric arc of a plasma flame spraying gun in response to an increase (or decrease) in the current of said circuit which comprises a voltmeter in said circuit operative to signal a compensating means, in turn, operative to decrease (or increase) the current in said circuit to maintain a proper current level at a given throughput of a specific plasma gas composition.

Automatic plasma flame spraying process and apparatus

A plasma flame-spraying apparatus, having a source of primary gas and a source of a secondary plasma gas, is provided with means for insuring that when the secondary gas in passed through the electric arc established in the flame-spraying apparatus, which secondary gas flow causes an increase in the voltage in the current of the circuit containing the arc, the current is suitably adjusted. The apparatus includes means for insuring that the ignition of the arc is established by pressing a single switch. There is also provided a closed loop system of determining the voltage changes in the arc circuit and for compensatingly regulating the current at a fixed plasma gas flow-through rate and composition to maintain a desired balance between current and secondary gas flow. Various automatic means are provided for insuring against excessive constriction of the confined electric arc within the nozzle of the apparatus or parts associated therewith.

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Middle Village, NY, United States of America

William A Vogts