Plasma transfer wire arc thermal spray system

Patent metadata

Field	Value
Publication number	US-10730063-B2
Application number	US-201013259433-A
Country	US
Kind code	B2
Filing date	Mar 31, 2010
Priority date	Mar 31, 2009
Publication date	Aug 4, 2020
Grant date	Aug 4, 2020

Abstract

In one or more embodiments, the invention relates to a plasma transfer wire arc thermal spray system, comprising a section for feeding a wire acting as a first electrode, a source of plasma gas providing plasma gas, a nozzle directing the plasma gas stream from the source of plasma gas to a free end of the wire, and a second electrode located in the plasma gas stream towards the nozzle. In certain instances, the nozzle is made at least partially of electrically insulating material. The thermal spray apparatus with the inventive spray gun may have a simplified and faster starting procedure and the spray nozzle can be more durable.

First claim

The invention claimed is:

1. A plasma transferred wire arc thermal spray apparatus comprising:
a nozzle having an orifice with an upstream and downstream side with respect to a plasma gas jet path and a secondary gas orifice proximate the orifice configured to supply a secondary gas downstream of the orifice to surround the plasma gas jet path,
a consumable feed wire electrode perpendicular to the plasma gas jet path and having a free end within the plasma gas jet path on the downstream side provided by a wire guide, and
a non-consumable second electrode on the upstream side, the non-consumable second electrode generating a transferred arc from the non-consumable electrode, through the orifice, to the free end of the consumable feed wire electrode,
wherein the nozzle has an inner portion adjacent the orifice oriented toward the second electrode, and an outer portion adjacent the orifice oriented toward the feed wire electrode, and wherein the nozzle comprises electrically insulative material at the inner portion and extending along the upstream side within the nozzle to inhibit a non-transferred arc between the nozzle and the second electrode.

2. The plasma transferred wire arc thermal spray apparatus of claim 1 , wherein the nozzle includes a nozzle body at least partially covered with electrically insulative material, wherein the electrically insulative material is arranged at a front side of the nozzle, in the nozzle orifice, or at a back side of the nozzle.

3. The plasma transferred wire arc thermal spray apparatus of claim 1 , wherein the nozzle comprises electrically insulating material at the outer portion.

4. The plasma transferred wire arc thermal spray apparatus of claim 1 , wherein the nozzle comprises electrically conductive material at its back side, the nozzle orifice, or both, and the conductive material is connected electrically to the second electrode or is acting as the second electrode.

5. The plasma transferred wire arc thermal spray apparatus of claim 4 , wherein a nozzle body or an inner part of the nozzle body is made of the conductive material.

6. The plasma transferred wire arc thermal spray apparatus of claim 1 , wherein the nozzle introduces a secondary gas around the plasma jet.

7. The plasma transferred wire arc thermal spray apparatus of claim 6 , wherein the nozzle includes a plurality of spaced converging secondary gas orifices surrounding the nozzle orifice.

8. The plasma transferred wire arc thermal spray apparatus of claim 1 , wherein the nozzle orifice is formed as a Laval nozzle.

9. The plasma transferred wire arc thermal spray apparatus of claim 1 , wherein the nozzle is made at least partially from an insulating material selected from the group consisting of SiN, Al 2 O 3 , ceramics, glass ceramics and SiC.

10. The plasma transferred wire arc thermal spray apparatus of claim 1 , wherein the apparatus includes a high voltage power source connected to first and second electrode generating direct current, alternating current, or high-frequency current.

11. A plasma transferred wire arc thermal spray apparatus for applying a coating to a surface, the apparatus comprising:
a nozzle having an upstream side and a downstream side with respect to an orifice, the nozzle configured to direct a gas flow through the orifice and defining at least one secondary gas orifice proximate the orifice for directing a secondary gas to surround the gas flow downstream of the orifice, the nozzle comprising an electrically insulating material at the orifice; the insulating material being configured to directly surround the gas flow along an entire length of the gas flow's path within the upstream side of the nozzle;
a first electrode comprising a feed wire fed by a roller perpendicular to the gas flow, the feed wire having a continuously fed free end in the gas flow downstream of the orifice and being configured to melt in response to an electrical arc; and
a second electrode located on the upstream of the orifice and terminating at a terminal end upstream of the orifice, the first and second electrodes being configured to transfer an electrical are from the terminal end of the second electrode to the first electrode, the are passing through the nozzle orifice, and terminating on the free end of the first electrode to melt the feed wire creating a liquid coating for depositing onto a surface by the gas flow;
wherein the electrically insulating material inhibits a non-transferred arc between the nozzle and the second electrode.

12. The plasma transferred wire are thermal spray apparatus of claim 11 , wherein the nozzle is coated at least partially with an insulative material.

13. The plasma transferred wire arc thermal spray apparatus of claim 11 , wherein an inner part of the nozzle toward the second electrode comprises an electrically insulative material, and an outer part of the nozzle radially outward of the inner part with respect to a center of the orifice, oriented toward the feed wire, on the downstream side of the nozzle orifice comprises an electrically non-insulative material.

14. The plasma transferred wire are thermal spray apparatus of claim 11 , wherein the nozzle comprises an electrically insulating material and is made at least partially from SiN, Al 2 O 3 , yttrium oxide, ceramics, glass ceramics, or SiC.

15. The plasma transferred wire are thermal spray apparatus of claim 11 , wherein the nozzle is a de Laval nozzle.

16. A plasma transferred wire arc thermal spray system comprising:
a nozzle defining an orifice and having a gas flow path therethrough with an upstream side and a downstream side with respect to the orifice and defining a secondary gas orifice proximate the orifice having a secondary gas flow path therethrough for surrounding the gas flow path downstream of the orifice; the nozzle having a plasma gas source in fluid communication with the upstream side of the nozzle;
a first electrode downstream of the orifice, the first electrode comprising a continuously fed feed wire perpendicular to the gas flow path, the feed wire having a melting point and a free end in the gas flow path downstream of the orifice, the first electrode being insulated from the nozzle with an electrically insulating material at the orifice;
a second electrode upstream of the orifice, the second electrode being electrically insulated from the nozzle, wherein the electrically insulating material is disposed along the entire gas flow path within the nozzle and at the nozzle orifice on an inner part of the nozzle between the first electrode and the second electrode to inhibit a non-transferred arc or pilot arc between the nozzle and the second electrode; and
a high voltage power source electrically coupled to the first and second electrodes and configured to generate an electric arc from the second electrode to the first electrode during start-up by providing up to 200 A of current without a pilot arc, the electric are passing through the orifice and having a temperature above the melting point of the feed wire to melt the feed wire at the free end.

17. The plasma transferred wire arc thermal spray system of claim 16 , wherein the nozzle includes a nozzle body made entirely of insulative material.

18. The plasma transferred wire arc thermal spray system of claim 16 , wherein the nozzle is a de Laval nozzle.

Assignees

• Schramm Leander
• Schwenk Alexander
• Hauser Enrico
• Ford Global Tech Llc

Inventors

• Schramm Leander
• Schwenk Alexander
• Hauser Enrico

Classifications

• B05B7/06

  with {at least} one outlet orifice surrounding another approximately in the same plane · CPC title

• B05B7/224 Primary

  the material having originally the shape of a wire, rod or the like · CPC title

• C23C4/131

  Wire arc spraying · CPC title

• B05B13/0636

  by means of rotatable spray heads or nozzles · CPC title

• H05H1/42

  with provisions for introducing materials into the plasma, e.g. powder or liquid {(arc stabilising or constricting arrangements H05H1/3405; coaxial protecting fluids H05H1/341)} · CPC title