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AssigneeFord Global Technologies, LLC
InventorsDaniel R. Marantz, Keith A. Kowalsky, James R. Baughman, David J. Cook
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A plasma transferred wire arc thermal spray apparatus and method producing an extended-arc and supersonic plasma jet stream for applying a dense metallic coating on a substrate, such as a concave internal surface of a bore. The apparatus includes a plasma generating torch assembling having a cathode and an anode nozzle surrounding the cathode and a wire feeder which continuously feeds the tip of a wire feedstock opposite a constricted nozzle orifice and wherein the wire feedstock is maintained at the same positive electrical potential as the nozzle. Plasma gas is directed into the nozzle, preferably generating a vortex flow around the cathode and exiting the restricted nozzle orifice. The improved apparatus includes a pilot power supply and a high voltage or high frequency power supply which initiates the electric arc and the constricted plasma arc and a separate main power supply which extends the constricted plasma arc to the wire tip. In the disclosed bore coating apparatus and method, the plasma torch assembly is rotated about the longitudinal axis of the wire feedstock while maintaining the electrical connection between the wire feedstock and the nozzle. The apparatus further includes an annular conical port surrounding the restricted nozzle orifice connected to a second gas source which generates an annular conical gas stream surrounding the wire tip having a point of intersection spaced downstream of the wire tip and the second gas is further directed to the wire feed guide to cool the assembly.
A plasma transferred wire arc thermal spray apparatus for applying a coating to a surface comprising a cathode having a first negative electrical potential, a nozzle generally surrounding a free end of said cathode in spaced relation having a restricted orifice opposite said cathode free end, said nozzle having a second positive electrical potential, a source of plasma gas directing plasma gas into said nozzle surrounding said cathode and exiting said restricted nozzle orifice, and a wire feed continuously directing a free end of wire feedstock opposite said restricted nozzle orifice and said wire feedstock having the same second positive electrical potential as said nozzle, said apparatus thereby establishing a plasma transferred-arc between said wire feedstock free end and said cathode melting said wire feedstock free end and said plasma gas exiting said restricted nozzle orifice atomizing melted feedstock and propelling atomized melted wire feedstock toward said surface, thereby coating said surface.
A plasma transferred wire arc bore coating apparatus comprising a plasma generating torch assembly including a cathode and a nozzle at least partially surrounding a free end of said cathode in spaced relation having a restricted nozzle orifice opposite said cathode free end, a wire feeder continuously directing a free end of wire feedstock opposite said restricted nozzle orifice, a power source and a source of plasma gas directing plasma gas into said nozzle surrounding said cathode and exiting said restricted nozzle orifice, said power source having a negative terminal operably connected to said cathode to establish a negative electrical potential of said cathode and a positive terminal operably connected to said wire feedstock to establish a positive electrical potential of said wire feedstock and said wire feedstock operably electrically connected to said nozzle to establish a positive electrical potential of said nozzle which is the same positive electrical potential as said wire feedstock, said plasma generating torch assembly generating a constricted plasma arc between said cathode and said wire feedstock free end thereby melting said wire feedstock free end and said plasma gas exiting said nozzle orifice atomizing molten feedstock and propelling atomized molten feedstock toward an internal surface of said bore, and said plasma generating torch assembly rotatably mounted to rotate about a longitudinal axis of said wire feedstock while maintaining said electrical connection to said nozzle, thereby directing said atomized molten feedstock rotatably to coat said internal surface of said bore.
A plasma transferred wire arc thermal spray apparatus comprising a plasma generating torch assembly including a cathode having a negative electrical potential and a nozzle having a positive electrical potential generally surrounding a free end of said cathode in spaced relation having a restricted nozzle orifice opposite said cathode free end, a source of plasma gas directing plasma gas under pressure into said nozzle exiting said nozzle restricted orifice, and a wire feeder continuously directing a free end of a wire feedstock opposite said restricted nozzle orifice, said wire feedstock having a positive electrical potential generally equal to said nozzle, said apparatus establishing a constricted plasma arc between said cathode and said wire feedstock free end, and said wire feedstock having a longitudinal axis defining an angle of less than 90.degree. relative to said restricted plasma arc, said constricted plasma arc melting said wire feedstock free end and said plasma gas atomizing molten feedstock and propelling atomized molten feedstock onto a work surface forming a dense metal coating on said surface.
A method of coating a surface with a dense metallic coating using a plasma transferred wire arc thermal spray apparatus, said apparatus including a cathode, a nozzle generally surrounding a free end of said cathode in spaced relation having a restricted orifice opposite said cathode free end and a wire feed directing a free end of a wire feedstock opposite said restricted nozzle orifice, said method comprising:
A method of coating an interior concave surface with a dense metallic coating using a plasma transferred wire arc thermal spray apparatus, said apparatus comprising a plasma generating torch assembly, a wire feed and a source of plasma gas, said plasma generating torch assembly including a cathode having a negative electrical potential and a nozzle having a positive electrical potential generally surrounding a free end of said cathode in spaced relation having a restricted nozzle orifice opposite said cathode free end, said wire feedstock in electrical contact with said nozzle and having the same positive electrical potential as said nozzle, and said plasma generating torch assembly rotatably mounted to rotate about a longitudinal axis of said wire feedstock, said method comprising:
Dependencies are inferred from the claim text.