Hybrid plasma-cold spray method and apparatus
AssigneeSulzer Metco (US), Inc.
InventorsRonald J. Molz, David Hawley, Richard McCullough
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Abstract
The present invention provides a method and apparatus of producing a dense coating with desirable stress conditions similar to coatings produced by a cold spray processes, but with higher process efficiencies and lower gas consumption. The inventive process combines features of a plasma process method of gas heating and a cold spray process to accelerate the gas, incorporating these elements into a single hybrid process.
Claims30
A method of applying a coating to a substrate, said method comprising the steps of:
- introducing a process gas into a thermal spray gun at a flow sufficient for ionization and acceleration for the application of coatings;
- ionizing the process gas using one or more electric arcs to heat the gas to temperatures in excess of 2,000 degrees C. with the one or more electric arcs occurring between one or more cathodes and one or more anodes, the one or more electric arcs being seated in an arc attachment step;
- accelerating the ionized plasma gas to supersonic velocities by a nozzle, having a convergent/divergent section with a throat therein between downstream of the arc attachment step;
- injecting material feed stock into the resulting high velocity hot gas/plasma stream downstream of the accelerating nozzle throat either internal to the bore of the nozzle or at the exit of the nozzle;
- and
- accelerating the material feed stock by the high velocity hot gas/plasma stream to achieve particle velocities from 600 to 2000 m/sec.
An apparatus for applying a thermal spray coating, comprising:
- one or more cathodes used as emitters for generating electrical arcs, said cathodes located such that gas suitable for ionization passes across the cathodes;
- a section of bore that is electrically neutral but can support the partial passage of an electric current during ignition to lengthen the arc and increase the voltage;
- an anode section that contains an arc attachment step or edge structured and arranged to seat an other end of the electrical arcs and stabilizing an arc length;
- a nozzle, having a convergent/divergent section with a throat therein between, downstream of the arc attachment step, wherein the geometry of the convergent/divergent section is such as to generate mach numbers in excess of 1;
- and
- one or more material feedstock injectors.
A hybrid plasma/cold spray systems, comprising:
- (a) a gun comprising
- one or more cathodes used as emitters for generating electrical arcs;
- a section of bore that can support the partial passage of an electric current during ignition to lengthen the arc and increase the voltage;
- an anode section that contains an arc attachment step or edge structured and arranged to seat an other end of the electrical arcs;
- a nozzle, having a convergent/divergent section and a throat, downstream of the arc attachment step, wherein the geometry of the convergent/divergent section is such as to generate mach numbers in excess of 1;
- and
- one or more material feedstock injectors;
- and
- (b) a gas consisting of one of air, argon, nitrogen, helium, hydrogen, oxygen, and any combination thereof for passing across said cathodes, wherein said gas is ionized by passing across said cathode to form ionized plasma gas, and said ionized plasma gas is accelerated to supersonic velocities, and wherein material feed stock is injected into the resulting high velocity ionized plasma and propelled toward a substrate.
Dependencies are inferred from the claim text.