PLASMA NOZZLE FOR A THERMAL SPRAY GUN AND METHOD OF MAKING AND UTILIZING THE SAME

Abstract

Plasma nozzle includes a nozzle body arranged to engage with a thermal spray gun. The nozzle body includes an axial through bore having up-stream input orifice and a down-stream nozzle exit, at least one material injector positioned between the up-stream input orifice and the nozzle-exit, said at least one material injector being configured to introduce a feedstock material into a gas flow passing through the axial through bore and at least one gas injector configured to introduce a shroud gas flow into the axial through bore and being located at a position up-stream of said at least one material injector.

Claims

1. A plasma nozzle comprising: a nozzle body arranged to engage with a thermal spray gun; the nozzle body comprising: an axial through bore having up-stream input orifice and a down-stream nozzle exit; at least one material injector positioned between the up-stream input orifice and the nozzle-exit, said at least one material injector being configured to introduce a feedstock material into a gas flow passing through the axial through bore; and at least one gas injector configured to introduce a shroud gas flow into the axial through bore and being located at a position up-stream of said at least one material injector.

2. The plasma nozzle of claim 1, wherein the at least one gas injector is an opening in a wall of the nozzle body and the at least one material injector is an opening in the wall of the nozzle body.

3. The plasma nozzle of claim 1, wherein the at least one gas injector is an opening in a wall of the nozzle body having a diameter or size that is less than a diameter or size of said at least one material injector.

4. The plasma nozzle of claim 1, wherein the at least one gas injector is a first opening and the at least one material injector is a second opening and wherein the first opening is arranged in a semi-circular or arc-shaped area defined by 3 times a diameter or size of the second opening and whose radius extends from a center axis of the second opening.

5. The plasma nozzle of claim 4, wherein the first opening comprises plural openings spaced from the center axis of the second opening by a same amount.

6. The plasma nozzle of claim 4, wherein the first opening comprises plural openings spaced from the center axis of the second opening by different amounts.

7. The plasma nozzle of claim 4, wherein the second opening comprises plural openings.

8. The plasma nozzle of claim 1, further comprising at least one down-stream gas injector positioned down-stream of said at least one material injector.

9. The plasma nozzle of claim 8, wherein the at least one down-stream gas injector comprises plural down-stream gas injectors positioned at an azimuthal angle relative to a center axis of the axial through bore.

10. The plasma nozzle of claim 1, wherein the nozzle body is an anode.

11. The plasma nozzle of claim 1, wherein the nozzle body is an anode of a thermal spray gun.

12. A thermal spray gun comprising a plasma nozzle of claim 1.

13. The plasma nozzle of claim 1, wherein the at least one gas injector is a circular opening in a wall of the nozzle body and the at least one material injector is a circular opening in the wall of the nozzle body.

14. The plasma nozzle of claim 1, wherein the at least one gas injector is a non-circular opening in a wall of the nozzle body and the at least one material injector is a circular opening in the wall of the nozzle body.

15. The plasma nozzle of claim 1, wherein the at least one gas injector is a circular opening in a wall of the nozzle body and the at least one material injector is a non-circular opening in the wall of the nozzle body.

16. The plasma nozzle of claim 1, wherein the at least one gas injector is a non-circular opening in a wall of the nozzle body and the at least one material injector is a non-circular opening in the wall of the nozzle body.

17. A thermal spray gun plasma nozzle comprising: an anode comprising: an axial through bore having up-stream input orifice and a down-stream nozzle exit; at least one material injector opening positioned between the up-stream input orifice and the nozzle-exit, said at least one material injector opening being configured to introduce a feedstock material into a gas flow passing through the axial through bore; and at least one gas injector opening configured to introduce a shroud gas flow into the axial through bore and being located at a position up-stream of said at least one material injector opening, wherein the at least one gas injector opening is smaller in diameter or size than the at least one material injector opening.

18. The plasma nozzle of claim 17, wherein the at least one gas injector opening is arranged in a semi-circular or arc-shaped area defined by 3 times a diameter or size of the at least one material injector opening and whose radius extends from a center axis of the at least one material injector opening.

19. The plasma nozzle of claim 17, wherein the at least one gas injector opening comprises plural openings spaced from the center axis of the at least one material injector opening.

20. The plasma nozzle of claim 17, wherein the at least one gas injector opening comprises plural openings spaced from the center axis of the at least one material injector opening by different amounts.

21. A thermal spray gun plasma nozzle comprising: an anode comprising: an axial through bore having up-stream input orifice and a down-stream nozzle exit; at least one material injector opening positioned between the up-stream input orifice and the nozzle-exit, said at least one material injector opening being configured to introduce a powder feedstock material into a gas flow passing through the axial through bore; and at least one gas injector opening configured to introduce an inert shroud gas flow into the axial through bore and being located at a position up-stream of said at least one material injector opening, wherein the at least one gas injector opening is smaller in diameter or size than the at least one material injector opening.

22. The plasma nozzle of claim 21, wherein the at least one gas injector opening is arranged in a semi-circular area defined by 3 times a diameter or size of the at least one material injector opening and whose radius extends from a center axis of the at least one material injector opening.

23. The plasma nozzle of claim 21, wherein the at least one gas injector opening comprises plural openings spaced from the center axis of the at least one material injector opening.

24. The plasma nozzle of claim 21, wherein the at least one gas injector opening comprises plural openings spaced from the center axis of the at least one material injector opening by different amounts.

25. A method of making the plasma nozzle of claim 1, the method comprising: arranging at least one gas injector opening upstream of at least one material injector opening and in a semi-circular or arc-shaped area defined by 3 times a diameter or size of the at least one material injector opening and whose radius extends from a center axis of the at least one material injector opening.

26. A method of using the plasma nozzle of claim 1, the method comprising: introducing, while powder is being introduced via the at least one material injector opening, an intern gas through at least one gas injector opening located upstream of at least one material injector opening and in a semi-circular or arc-shaped area defined by 3 times a diameter or size of the at least one material injector opening and whose radius extends from a center axis of the at least one material injector opening.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The accompanying drawings are included to provide further understanding of the invention and are incorporated in and constitute a part of this specification. The accompanying drawings illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. In the figures:

[0049] FIG. 1 shows a prior art VPS F4 spray gun employing internal injection of powder material inside the anode;

[0050] FIG. 2 shows a prior art arrangement that employs an internal shroud gas film;

[0051] FIG. 3 shows a cross-section of a section of an anode which can be used to practice the invention and illustrates various locations and area sizes;

[0052] FIGS. 4A and 4B show cross-sections of a section of anode in accordance with one non-limiting embodiment of the invention. The cross-section of FIG. 4B is schematic and taken orthogonal relative to the cross-section of FIG. 4A;

[0053] FIGS. 5A and 5B show cross-sections of a section of anode in accordance with another non-limiting embodiment of the invention. The cross-section of FIG. 5B is schematic and taken orthogonal relative to the cross-section of FIG. 5A;

[0054] FIGS. 6A and 6B show cross-sections of a section of anode in accordance with another non-limiting embodiment of the invention. The cross-section of FIG. 6B is schematic and taken orthogonal relative to the cross-section of FIG. 6A;

[0055] FIGS. 7A and 7B show cross-sections of a section of anode in accordance with another non-limiting embodiment of the invention. The cross-section of FIG. 7B is schematic and taken orthogonal relative to the cross-section of FIG. 7A; and

[0056] FIG. 8 shows an exemplary powder port with arc-shaped areas defined by different diameters of an oblique ellipse shaped powder injector opening.

DETAILED DESCRIPTION OF THE INVENTION

[0057] The following detailed description illustrates by way of example, not by way of limitation, the principles of the disclosure. This description will clearly enable one skilled in the art to make and use the disclosure, and describes several embodiments, adaptations, variations, alternatives and uses of the disclosure, including what is presently believed to be the best mode of carrying out the disclosure. It should be understood that the drawings are diagrammatic and schematic representations of exemplary embodiments of the disclosure and are not limiting of the present disclosure nor are they necessarily drawn to scale.

[0058] The novel features which are characteristic of the disclosure, both as to structure and method of operation thereof, together with further aims and advantages thereof, will be understood from the following description, considered in connection with the accompanying drawings, in which an embodiment of the disclosure is illustrated by way of example. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only, and they are not intended as a definition of the limits of the disclosure.

[0059] In the following description, the various embodiments of the present disclosure will be described with respect to the enclosed drawings. As required, detailed embodiments of the present disclosure are discussed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the embodiments of the disclosure that may be embodied in various and alternative forms. The figures are not necessarily to scale and some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present disclosure.

[0060] The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present disclosure only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present disclosure. In this regard, no attempt is made to show structural details of the present disclosure in more detail than is necessary for the fundamental understanding of the present disclosure, such that the description, taken with the drawings, making apparent to those skilled in the art how the forms of the present disclosure may be embodied in practice.

[0061] As used herein, the singular forms a, an, and the include the plural reference unless the context clearly dictates otherwise. For example, reference to a powder material would also mean that mixtures of one or more powder materials can be present unless specifically excluded. As used herein, the indefinite article a indicates one as well as more than one and does not necessarily limit its referent noun to the singular.

[0062] Except where otherwise indicated, all numbers expressing quantities used in the specification and claims are to be understood as being modified in all examples by the term about. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and claims are approximations that may vary depending upon the desired properties sought to be obtained by embodiments of the present disclosure. At the very least, and not to be considered as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed in light of the number of significant digits and ordinary rounding conventions.

[0063] Additionally, the recitation of numerical ranges within this specification is considered to be a disclosure of all numerical values and ranges within that range (unless otherwise explicitly indicated). For example, if a range is from about 1 to about 50, it is deemed to include, for example, 1, 7, 34, 46.1, 23.7, or any other value or range within the range.

[0064] As used herein, the terms about and approximately indicate that the amount or value in question may be the specific value designated or some other value in its neighborhood. Generally, the terms about and approximately denoting a certain value is intended to denote a range within 5% of the value. As one example, the phrase about 100 denotes a range of 1005, i.e. the range from 95 to 105. Generally, when the terms about and approximately are used, it can be expected that similar results or effects according to the disclosure can be obtained within a range of 5% of the indicated value.

[0065] As used herein, the term and/or indicates that either all or only one of the elements of said group may be present. For example, A and/or B shall mean only A, or only B, or both A and B. In the case of only A, the term also covers the possibility that B is absent, i.e. only A, but not B.

[0066] The term at least partially is intended to denote that the following property is fulfilled to a certain extent or completely.

[0067] The terms substantially and essentially are used to denote that the following feature, property or parameter is either completely (entirely) realized or satisfied or to a major degree that does not adversely affect the intended result.

[0068] The term comprising as used herein is intended to be non-exclusive and open-ended. Thus, for example a composition comprising a compound A may include other compounds besides A. However, the term comprising also covers the more restrictive meanings of consisting essentially of and consisting of, so that for example a composition comprising a compound A may also (essentially) consist of the compound A.

[0069] The various embodiments disclosed herein can be used separately and in various combinations unless specifically stated to the contrary.

[0070] The invention will now be described with reference to FIG. 3 which show a cross-section of a section of anode An having a powder inlet or injection port P having a diameter d located in a wall W of the anode An. The port P can extend through the wall W in a manner similar to that shown in FIG. 1. The semi-circular area labeled with the letter A shows an area where one can place one or more shroud gas inlets which will be located in proximity to the port P. The area A around the powder port P is located upstream of the port P and is defined by a diameter that is 3 times the diameter d of the port P. A second larger area B may also include additional optional gas inlets and extends from an upstream location x to a downstream location y. For example, in an LPPS and PS-PVD type system, a common powder port P diameter d is 3 mm. Therefore, in such an application, at least one gas inlet (not shown) should be placed upstream in the area A which is defined by a semi-circle having a diameter of 9 mm. Upstream from the powder port P, one can place additional gas inlets within the 9 mm area A and can also place one or more additional gas inlets either upstream or downstream from the port P and outside the half-circle area A, i.e., in area B.

[0071] FIGS. 4A and 4B show two orthogonal cross-sections of an embodiment of an anode An which includes 5 gas inlets I in area A of FIG. 3, at equal distance from the powder port P and in close proximity of the powder port P. With such an arrangement, the carrier gas material build-up around the powder port P is avoided. With such an arrangement, the total shroud gas flow through all gas inlet bores I can be varied from 50% to 150% with respect to the carrier gas flow through the anode An. Preferably, gas flows is provided through the inlets I in a flow that is below 100% of the carrier gas flow. Moreover, in case the spraying conditions are those used in LPPS in which the material vaporizes, one should be mindful that shroud gas flows which are too high can lead to undesirable re-condensation. The flow of carrier gas and shroud gas can be 10% to 30% compared to the gas flows used to create the plasma gas jet. The carrier gas flow can also be split in several powder port injectors or ports P, as well as the shroud gas inlets I. Typically, total carrier gas flows can be between 5 and 60 NLPM (Normal Liter Per Minute). They can also be between 20 and 50 NLPM, and are preferably between 25 and 40 NLPM. On the other hand, the shroud gas flow through the inlets I can be set between 5 and 80 NLPM, typically between 20 and 75 NLPM, and preferably between 25 and 40 NLPM.

[0072] FIGS. 5A and 5B show another embodiment of an anode An having one or more powder injection ports P and plural gas inlets I. In this case the gas inlets I are located in area A of FIG. 3 at varying distance from the powder port P. Downstream of the port P there are arranged additional gas inlets I and are placed at a further azimuthal angle with respect to the powder port P with some inlets I located in area B of FIG. 3. This embodiment is designed to generate a gas shroud that follows the diffusion of the injected carrier gas. In addition to forming a protective gas shroud between the anode wall and the material/plasma jet, this configuration also leads to deflecting the injected powder material towards an anode axis into the zone of the highest plasma temperatures. Numerical simulations indicate that this will improve heat transfer from the hot plasma jet to the powder particles, which leads to a higher efficiency with respect to the material deposit versus the amount of injected material. Especially in cases of PS-PVD spraying, in which the powder material is transferred into the vapor phase, a larger share of the powder material will be vaporized compared to the classic anode design which lacks the shroud gas inlets. As with the previous embodiment, the inlets I in area A function to prevent material build-up in a most critical zone around the powder injection port P. However, in this embodiment, the inlets I located in area B function to prevent material build-up in the anode wall.

[0073] FIGS. 6A and 6B show another embodiment of an anode An having one or more powder injection ports P and plural gas inlets I. In this case some gas inlets I are located in area A of FIG. 3 at varying distance from the powder port P. Downstream of the port P there are arranged additional gas inlets I and these are placed at a further azimuthal angle with respect to the powder port P with some inlets I located in area B of FIG. 3. In addition, one or more gas inlets I are located in area B between the inlets I arranged in azimuthal angle with respect to the powder port P and these form a generally circular group of gas inlets I which surround the powder port P. This embodiment is also designed to generate a gas shroud that follows the diffusion of the injected carrier gas. In addition to forming a protective gas shroud between the anode wall and the material/plasma jet, this configuration also leads to deflecting the injected powder material towards an anode axis into the zone of the highest plasma temperatures. It is believed that this arrangement can improve heat transfer from the hot plasma jet to the powder particles, which can lead to a higher efficiency with respect to the material deposit versus the amount of injected material. Especially in cases of PS-PVD spraying, in which the powder material is transferred into the vapor phase, a larger share of the powder material will be vaporized compared to the classic anode design which lacks the shroud gas inlets. As with the previous embodiment, the inlets I in area A function to prevent material build-up in a most critical zone around the powder injection port P. However, in this embodiment, the inlets I located in area B are believed to function to prevent material build-up in the anode wall.

[0074] FIGS. 7A and 7B show another embodiment of an anode A n having one or more powder injection ports P and a single arc-shaped gas inlet I. In this case the arc-shaped gas inlet I is located in area A of FIG. 3 with end portions being located a varying distance from the powder port P. Downstream of the port P one could arrange additional gas inlets I (not shown in FIG. 7) in a manner similar to previous embodiments. This embodiment can also be designed to generate a gas shroud that follows the diffusion of the injected carrier gas. In addition to forming a protective gas shroud between the anode wall and the material/plasma jet, this configuration also leads to deflecting the injected powder material towards an anode axis into the zone of the highest plasma temperatures. It is believed that this arrangement can improve heat transfer from the hot plasma jet to the powder particles, which can lead to a higher efficiency with respect to the material deposit versus the amount of injected material. Especially in cases of PS-PVD spraying, in which the powder material is transferred into the vapor phase, a larger share of the powder material will be vaporized compared to the classic anode design which lacks the shroud gas inlets. As with the previous embodiment, the elongate arc-shaped inlet I in area A functions to prevent material build-up in a most critical zone around the powder injection port P.

[0075] The powder injection port P, P, P or P as well as the gas injector ports or inlets I, I, I and I can be either circular or non-circular shaped such as oval or elliptical (e.g., oblique ellipse) with the elongate ends oriented in a direction that is upstream/downstream. FIG. 8 shows an example of an oblique ellipse shaped powder port P. In such cases, one can define the port P by either an average diameter or by a size of the opening. Alternatively, one can define such openings as having a diameter that is defined as the larger distance (based on using the major axis) of the opening, i.e., the larger vertical arrow R1 in FIG. 8. When defining area A, one can use the vertical arrow R1 to determine the 3 times distance D1 of the same for area A (which represents an area covered by the larger semi-circle in FIG. 8) or one can use the horizontal arrow R2 (based on using the minor axis) to determine the 3 times distance D2 of the same for area A (which represents an area covered by the smaller semi-circle in FIG. 8). The invention contemplates using either option in the case of such non-circular openings or ports P. Alternatively, one can define the opening or port P by its open area and this can used this as its size. In addition to circular, oval or elliptical shapes for the ports can have other shapes such as generally rectangular, square, triangular, etc.

[0076] The gas inlets I, I, I and I of the shroud generating gas flow of the invention can be arranged in the section of the anode An, An, An and A n where the powder injection port P, P, P and P is located. The powder material can be injected from one or several powder ports. The possible and optimum zones where the shroud gas inlet(s) should be positioned can be upstream from the powder port as well as downstream between the powder port and towards the anode exit. The total gas flow through the one or several shroud gas inlets can be between 50% and 150% of the total carrier gas flow that is injected through the powder ports. The injected shroud gas can be any inert gas, in particular, argon or helium, but could be also a diatomic gas such as nitrogen. The shroud gas may be the same or different from the carrier gas that is used to inject the powder particles. The diameter of each shroud gas inlet I, I, I and I can be between 20% and 120%, in particular 20% to 80%, preferably 20% to 50%, compared to the diameter of powder port P, P, P and P.

[0077] In all arrangements, there should be at least one shroud gas inlet that can be located upstream from the powder port. There should be at least one upstream inlet located in an area whose radius is a maximum 3 times the powder port diameter or size around the powder port P, P, P or P. Additional shroud gas inlets I, I, I or I may be placed upstream in the area of maximum 3 times the powder port diameter or size in length with respect to the powder port P over the full circumference. Downstream of the powder port, they may be located at any distance between the powder port P, P, P or P and the anode exit over the full circumference. The diameter or size of the shroud gas inlets I, I, I or I may vary by 100% when one compares the smallest and biggest diameter. The area in which at least one gas inlet is placed can be characterized as an area A or first area (see FIG. 3). The area in which additional inlets can be placed in different arrangements and in an undefined number can be characterized as an area B or second area (see FIG. 3). Typically, a powder port diameter of the powder port in vacuum type systems is between 0.5 and 5 mm, in particular, between 1 to 3 mm. Practical examples have demonstrated that a shroud gas inlet I, I, I or I diameter of the gas inlets I of between 0.5 and 1.5 mm, preferably between 0.75 and 1 mm, can provide best results. Similar to the powder injection port P, P, P or P, the injection of the shroud gas via inlets I, I, I or I, can have different directions with respect to the flow of the primary process gas axially and radially inducing some swirl effect to follow or counter the flow and/or swirl flow of the primary process gas flow.

[0078] Further, at least because the invention is disclosed herein in a manner that enables one to make and use it, by virtue of the disclosure of particular exemplary embodiments, such as for simplicity or efficiency, for example, the invention can be practiced in the absence of any additional element or additional structure that is not specifically disclosed herein.

[0079] It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to an exemplary embodiment, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.