Coated nozzle for an arc torch

Abstract

The invention discloses a coated nozzle for an arc torch. In one aspect, a nozzle for an arc torch is described herein that includes a refractory coating that increases the operational life of the nozzle by resisting weld molten metal spatter and associated accumulation of molten metal deposits. In one aspect, a nozzle for an arc torch includes a first body including a central bore and an outer surface. The coating adheres to the outer surface by thermal spraying, physical vapor deposition (PVD) or chemical vapor deposition (CVD), the coating comprising a refractory layer comprising one or more metal elements selected from the group consisting of aluminum, silicon, and metal elements of groups IIIB-VIIIB of the periodic table; and one or more non-metallic elements selected from groups IIIA, IVA, VA and VIA of the periodic table.

Description

[0001] This application is a divisional application of the invention patent application with application date of September 18, 2020 and application number 202010985989.1. Technical Field

[0002] The present invention relates to electric arc welding torches, and more particularly, to welding torch nozzles including a refractory coating. Background Art

[0003] Generating plasma for cutting or welding is an important tool in the metalworking industry. Plasma is generated during various processes, including plasma transferred arc welding, MIG welding (also known as GMAW), TIG welding (also known as GTAW), plasma cutting, and plasma spraying. In these methods, plasma can reach temperatures in excess of 20,000°F. At these temperatures, cutting and welding slag are usually abundant and inevitably deposited on welding equipment. Therefore, equipment maintenance is required on a regular basis. Maintenance may include cleaning or replacing parts with molten metal deposits. When welding, for example, with PTA, MIG, or plasma cutting, welding fumes and welding slag tend to accumulate on the nozzle surface, thereby interrupting arc transfer, reducing welding and / or cutting efficiency, and clogging powder or wire ports. Typically, depending on the severity of the accumulation, welding or cutting will be stopped to clean the nozzle surface or replace the nozzle completely. Such stops are very common because current nozzles generally exhibit a maximum of 1-2 hours of continuous cutting or welding time. This limited operating time window limits welding and cutting efficiency and increases operating costs. Summary of the invention

[0004] In one aspect, a nozzle for an arc welding torch is described herein, the nozzle comprising a refractory coating that increases the operating life of the nozzle by resisting the accumulation of weld molten metal spatter and associated molten metal deposits. In one aspect, the nozzle for an arc welding torch comprises a first body comprising a central hole and an outer surface. The coating is adhered to the outer surface by thermal spraying, physical vapor deposition (PVD), or chemical vapor deposition (CVD), the coating comprising a refractory layer comprising one or more metallic elements selected from the group consisting of: aluminum, silicon, and metallic elements of Groups IIIB-VIIIB of the Periodic Table; and one or more non-metallic elements selected from Groups IIIA, IVA, VA, and VIA of the Periodic Table. In some embodiments, the refractory layer exhibits a critical load (L c ) and / or residual compressive stress conditions of at least 2 GPa. In addition, the coated nozzles described herein exhibit a continuous welding life that can be twice the life of uncoated nozzles.

[0005] In another aspect, a method of welding or cutting is described herein. In some embodiments, the method includes providing an arc welding torch including a nozzle, the nozzle comprising a first body, the first body comprising a central hole and an outer surface; and a coating adhered to the outer surface by thermal spraying, physical vapor deposition (PVD) or chemical vapor deposition (CVD). The coating includes a refractory layer, the refractory layer comprising one or more metallic elements selected from the group consisting of aluminum, silicon and metal elements of Groups IIIB-VIIIB of the Periodic Table; and one or more non-metallic elements selected from Groups IIIA, IVA, VA and VIA of the Periodic Table. Welding and / or cutting metal or alloy workpieces with a plasma torch. In some embodiments, the continuous welding or cutting life of the coated nozzle is twice that of the continuous welding or cutting life of the uncoated nozzle.

[0006] These and other embodiments are described in more detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 A perspective view of a coated nozzle is shown according to some embodiments.

[0008] Figure 2 According to some embodiments, Ti adhered to the outer surface of the nozzle 0.40 Al 0.60 Cross-sectional scanning electron (SEM) micrograph of N coating.

[0009] Figure 3 After seven hours of continuous welding of Stellite 6 alloy Figure 1 Picture of the nozzle. DETAILED DESCRIPTION

[0010] The embodiments described herein can be more easily understood by reference to the following detailed description and examples and its previous description and the following description. However, the elements, devices and methods described herein are not limited to the specific embodiments presented in the detailed description and examples. It should be appreciated that these embodiments are merely illustrative of the principles of the present invention. Those skilled in the art will readily appreciate many modifications and adjustments without departing from the spirit and scope of the present invention.

[0011] I. Arc welding torch nozzle

[0012] As described herein, a nozzle for an arc torch includes a first body including a central hole and an outer surface. A coating is adhered to the outer surface by thermal spraying, physical vapor deposition (PVD), or chemical vapor deposition (CVD), the coating including a refractory layer comprising one or more metallic elements selected from the group consisting of aluminum, silicon, and metallic elements of Groups IIIB-VIIIB of the Periodic Table; and one or more non-metallic elements selected from Groups IIIA, IVA, VA, and VIA of the Periodic Table.

[0013] Turning now to specific components, the refractory layer may include any composition within the above parameters. The refractory layer may, for example, include a carbide, nitride, carbonitride, oxide, oxynitride, or oxycarbonitride of one or more metals selected from the group consisting of aluminum, silicon, and metal elements of Groups IIIB-VIIIB of the periodic table. In some embodiments, for example, the refractory layer includes M 1-x Al x N, wherein 0.3≤x≤0.9 and M is titanium, chromium or zirconium. In some embodiments, 0.4≤x≤0.6. The refractory layer may also include Ti 1-x-y Me y Al x N, wherein Me is selected from Groups IVB-VIB of the periodic table, and x>0, y≥0 and 0.3≤x+y≤0.9. Alternatively, the refractory layer may include a metal oxide. In some embodiments, the oxide is selected from the group consisting of chromium oxide, yttria-stabilized zirconium oxide, and titanium aluminum oxide. The ceramic properties of the refractory layer described herein make the refractory layer electrically insulating.

[0014] The refractory layer can be deposited by physical vapor deposition (PVD), chemical vapor deposition (CVD) or thermal spraying. In some embodiments, the refractory layer exhibits a compressive residual stress condition. In some embodiments, the refractory layer, for example, can have a residual compressive stress of at least 2 GPa. The refractory layer can also have a residual compressive stress selected from Table 1.

[0015] Table I - Residual compressive stress of refractory layer

[0016] Residual compressive stress, GPa 1-4 2-4 0.5-3 0.1-1

[0017] In the absence of a specific indication that it is compressive, the residual stress values ​​described herein may be assigned a negative value to indicate that the residual stress is compressive stress. It will be understood by those skilled in the art that, in the absence of a specific indication, the residual stress is assigned a positive value to indicate tensile stress, and a negative value to indicate compressive stress.

[0018] For the refractory layer described in this paper, a modified Sin 2The ψ method uses the Seemann-Bohlin (SB) focusing geometry to determine residual stresses and shear stresses. See V. Valvoda, R. Kuzel, R. Cerny, DS Rafaja, J. Musil, C. Kadlec, AJPerry, Thin Solid Films 193 / 194 (1990) 401. According to this method, the plane spacing of all measurable diffraction peaks with different Miller (hkl) indices is determined using grazing incidence X-ray diffraction geometry. [Diffraction peaks from different (hkl) planes are collected in a single 2θ scan at a fixed incident beam angle to the sample.] Since in the method of Perry et al., the diffraction planes make different angles with the sample surface normal, there is no need to tilt the sample ψ. Perry et al. proposed that the angle ψ actually corresponds to the Bragg angle θ minus the grazing angle γ (ψ = θ-γ). Therefore, in a single 2θ scan, when multiple Bragg peaks with different Miller indices are measured at different 2θ angles, the range of ψ angles is automatically selected. 2 The plot of the variation of ψ gives the residual stresses.

[0019] For including M 1-x Al x N and where M is a titanium refractory layer, for example, the residual stress and shear stress are determined by X-ray diffraction using grazing incidence Sin 2 The ψ method is determined for multiple (hkl) reflections of the TiAlN crystalline phase. The instrument used to determine the residual stress is a PANalytical Xpert Pro MRD equipped with a Eulerian holder for sample manipulation. The x-ray source is a copper long fine focusing x-ray tube operated at 45KV and 40MA. The instrument is configured with a parallel beam optical device for determining the stress in the coating. The incident optical device includes an x-ray mirror and a 0.04 degree soller slit. The receiving optical device includes a 0.27 degree parallel plate collimator, a flat graphite monochromator and a sealed proportional counter.

[0020] The (111), (200), (220), (311), (222), (331), (420) and (422) reflections of AlTiN were selected to measure the residual stress levels. The grazing incidence angle was chosen to minimize substrate reflections while ensuring that the entire refractory thickness was included in the analysis. For each (hkl) reflection, the data acquisition parameters for step size and counting time were adjusted to obtain the appropriate peak intensity, thereby accurately determining the peak position.

[0021] Next, the peak data was corrected for absorbance and clarity using the following formula:

[0022] Absorption correction

[0023]

[0024] Transparency Correction

[0025]

[0026] in

[0027] and

[0028] in:

[0029] t = layer thickness

[0030] μ=linear absorption coefficient (cm -1 )

[0031] θ=2θ / 2(degrees)

[0032] (ω-θ) = ω deviation angle (degrees)

[0033] ψ=Tilt angle (Psi stress) (degrees)

[0034] τ = information depth (micrometers)

[0035] R = radius of the goniometer (mm)

[0036] The peak data were corrected for Lorentz polarization using the following formula:

[0037] Polarization correction

[0038]

[0039] 2θ mon = diffraction angle of graphite monochromator

[0040] The Kα2 peak was removed using the Ladell model. The peak positions were refined using a modified Lorentzian shape profile function.

[0041] The refractory residual stress is calculated by the following general formula:

[0042]

[0043] where σ φ =σ1cos 2 φ+σ2sin 2 φ

[0044] =In the corner and the lattice constant at the tilt angle ψ

[0045] d o = strain-free lattice constant

[0046] =Rotation angle

[0047] ψ = sample inclination angle

[0048] σ1 and σ2 = principal stress tensors in the specimen surface

[0049] =In Stress under rotation angle

[0050] S1 & 1 / 2S2 = X-ray elastic constant

[0051]

[0052] For the TiAlN of the present invention, the Poisson's Ratio (υ) is set to 0.20, and the elastic modulus (E, in GPa) is determined by nanoindentation analysis performed with a Fischerscope HM2000 using a Vickers indenter according to ISO standard 14577. The indentation depth is set to 0.25 μm. As known to those skilled in the art, for refractory layers with other compositions, residual stress analysis can be performed using XRD in a similar manner by selecting multiple (hkl) reflections suitable for these compositions. In addition, the Poisson's ratio (υ) and elastic modulus (E) of other refractory layers can also be determined by nanoindentation analysis as described herein.

[0053] In some embodiments, the fire resistant layer of the coating may exhibit a critical load (L c In other embodiments, the fire-resistant layer exhibits a critical load (L of at least 60 kgf). c ). The critical load of the fire-resistant layer may also have a value selected from Table II.

[0054] Table II - Critical load of fire resistant layer (L c )

[0055] 45-60kgf 60-100kgf ≥100kgf

[0056] The critical load for characterizing the adhesion of the refractory layer is determined according to the following scheme. A Vicker indenter with a surface scale is used, which has no cracks, cracks, defects and adhered surface debris. A point anvil (0.25 inch diameter) and a flat anvil (2 inch diameter) are also used. Select an appropriate preload (10kg) to apply the indenter load. Select the flat surface of the coated substrate, and adjust the position on the anvil and below the diamond indenter and the lifting screw to the desired zero scale position. Apply an indentation under the desired surface load (e.g., 45, 60, 100, 150kgf, etc.). Release the lifting screw and position the sample laterally to apply the next load. The indentations are spaced apart to avoid the interference effect or influence of adjacent indentations. The recommended spacing distance is 3-5× the diameter of the indentation. By immersing the sample in an ultrasonic bath for several minutes, any debonded but still adhered refractory layer can be removed. Alternatively, a tape can be used to remove the debonded refractory layer. Under an optical microscope (10×-100×), the peeling and delamination of the dented sample were examined along the surface periphery of the dent. Critical load (L c ) is reported as a load at which coating spalling and / or delamination occurs beyond the indent diameter. The refractory layer described herein may have any desired thickness. The thickness of the refractory layer may be selected based on several considerations, including but not limited to the compositional properties of the layer and the deposition technique. The PVD or CVD refractory layer may generally have a thickness of 1-10 μm. In some embodiments, the thickness of the PVD or CVD refractory layer is 2-5 μm. Alternatively, the refractory layer deposited by thermal spraying may have a thickness of 25 μm to 500 μm.

[0057] In some embodiments, the refractory layer may undergo one or more post-coating treatments. The refractory layer may be, for example, sandblasted with various wet and / or dry particle compositions. Post-coating sandblasting may be applied in any desired manner. In some embodiments, post-coating sandblasting includes shot blasting or pressurized sandblasting. Pressurized sandblasting may be applied in a variety of forms, including compressed air sandblasting, wet compressed air sandblasting, pressurized liquid sandblasting, wet sandblasting, and steam sandblasting. For example, wet sandblasting is achieved using a slurry of inorganic and / or ceramic particles such as aluminum oxide and water. The particle slurry may be pneumatically sprayed onto the surface of the coated cutting tool body to impact the surface of the coating. The size of the inorganic and / or ceramic particles may generally be in the range of about 20 μm to about 100 μm. Sandblasting parameters include pressure, impact angle, distance from the component surface, and duration.

[0058] In other embodiments, the refractory layer undergoes a post-coating polishing process. Polishing can be applied with a paste having an appropriate diamond or ceramic grit size. In some embodiments, the grit size of the paste is in the range of 1 μm to 10 μm. In one embodiment, a 5-10 μm diamond grit paste polishing coating is used. The refractory layers described herein may be sandblasted or polished for a period sufficient to achieve the desired surface roughness (R a ) and / or other parameters, such as the time to increase the residual compressive stress of the refractory layer. In some embodiments, the refractory layer subjected to post-coating treatment has a surface roughness (R a ).

[0059] Table III - Surface roughness after coating (R a )–nm

[0060] ≤500 ≤250 <200

[0061] In some embodiments, the refractory layer may be directly adhered to the outer surface of the nozzle. Alternatively, the coating may also include one or more intermediate layers between the outer surface of the nozzle and the refractory layer. The intermediate refractory layer of the coating may include one or more metal elements selected from the group consisting of aluminum and metal elements of Groups IVB, VB and VIB of the periodic table, and one or more non-metallic elements selected from the group consisting of non-metallic elements of Groups IIIA, IVA, VA and VIA of the periodic table. For example, in some embodiments, one or more intermediate layers of TiN, AlTiN, TiC, TiCN or Al2O3 may be positioned between the outer surface of the nozzle and the refractory layer. The intermediate layer may have any desired thickness consistent with the purpose of the present invention. In some embodiments, the intermediate layer has a thickness in the range of 100nm to 5μm.

[0062] As described herein, the nozzle of an arc torch includes a first body, the first body including a central hole and an outer surface. In some embodiments, a second body is arranged in the central hole, wherein a channel is formed between the first body and the second body. The second body may, for example, be concentrically arranged in the central hole of the first body. Similarly, the nozzle may include an additional body arranged in the central hole, wherein a channel is formed between the second body and the additional body. The channel formed between the first body, the second body and / or the additional body may perform various functions, including passages for shielding gas, water cooling and / or powdered or wire-shaped welding materials. Depending on the function, the second body and / or the additional body may be uncoated or at least partially coated with the refractory layer described herein.

[0063] Figure 1 A perspective view of a coated nozzle is shown according to some embodiments. Figure 1 As shown in , the nozzle includes an outer surface to which a coating is adhered. Figure 1 In the embodiment of Ti0.40 Al 0.60 N refractory layer adheres to the outer surface. Ti 0.40 Al 0.60 The N refractory layer is gray in color. The nozzle includes a central orifice for transferring the arc generated by the welding torch to the workpiece. The nozzle also includes two orifices adjacent to the central orifice. These orifices can transport shielding gas or powdered welding material. Figure 2 It is Ti adhered to the outer surface of the nozzle. 0.40 Al 0.60 Cross-sectional SEM of N refractory layer.

[0064] The nozzle can be formed of any material consistent with the purpose of the present invention. In some embodiments, for example, the nozzle is formed of copper or a copper alloy. The continuous welding or cutting life exhibited by the nozzle including the coating described herein can be twice the life of the uncoated nozzle. The continuous welding or cutting life refers to the time when the welding torch generates an arc and participates in the welding or cutting operation. Therefore, the continuous welding or cutting life does not include the time when the welding torch does not generate an arc. In some embodiments, the nozzle described herein has a continuous welding or cutting life of at least 5 hours. The coated nozzle described herein can be used for any type of arc torch, including a plasma arc torch, a plasma transfer arc torch, a plasma cutter and / or a torch for MIG welding and TIG welding.

[0065] Figure 1 The coated nozzle was subjected to 7 hours of continuous welding of Stellite 6 alloy. The coated nozzle is commercially available from Kennametal Stellite Part of a welding torch. Figure 3 is a picture of the nozzle at 7 hours completion. It is noteworthy that the central orifice and adjacent orifices were not blocked by molten metal deposits generated by weld metal splash. A comparative uncoated insert was also subjected to use Continuous welding of Stellite 6 alloy by a welding torch. After three hours of continuous welding, the uncoated nozzle needed to be replaced.

[0066] II. Methods of welding and / or cutting

[0067] In another aspect, a method of welding or cutting is described herein. In some embodiments, the method includes providing an arc torch including a nozzle, the nozzle comprising a first body, the first body comprising a central hole and an outer surface; and a coating adhered to the outer surface by thermal spraying, physical vapor deposition (PVD) or chemical vapor deposition (CVD). The coating includes a refractory layer, the refractory layer comprising one or more metal elements selected from the group consisting of: aluminum, silicon and metal elements of Groups IIIB-VIIIB of the periodic table; and one or more non-metallic elements selected from Groups IIIA, IVA, VA and VIA of the periodic table. Metal or alloy workpieces are welded and / or cut with an arc torch. In some embodiments, the continuous welding or cutting life of the coated nozzle is twice that of the continuous welding or cutting life of the uncoated nozzle. The nozzle used in the method described herein may have any composition and / or characteristics described in Part I above. The coated nozzle described herein can be used for any type of arc torch, including a plasma arc torch, a plasma transfer arc torch, a plasma cutter and / or a torch for MIG welding and TIG welding.

[0068] Various embodiments of the present invention have been described in the realization of the various objects of the present invention. It should be recognized that these embodiments are only illustrative of the principles of the present invention. Many modifications and adjustments will be readily apparent to those skilled in the art without departing from the spirit and scope of the present invention.

Claims

1. A nozzle for an arc welding torch, the nozzle comprising: a first body comprising a central hole and an outer surface; as well as An electrically insulating coating adhered to the outer surface by physical vapor deposition (PVD) or chemical vapor deposition (CVD), the coating comprising a refractory layer comprising one or more metallic elements selected from the group consisting of aluminum, silicon, and metallic elements of Groups IIIB-VIIIB of the Periodic Table; and one or more non-metallic elements selected from Groups IIIA, IVA, VA, and VIA of the Periodic Table. 2 . The nozzle according to claim 1 , wherein the refractory layer has a thickness of 1 μm to 10 μm.

3. The nozzle of claim 1, wherein the refractory layer has a critical load (L c ).

4. The nozzle of claim 1, wherein the refractory layer has a critical load (L c ).

5. The nozzle of claim 1, wherein the refractory layer has a compressive residual stress of at least 2 GPa. The nozzle of claim 1 , wherein the refractory layer has a compressive residual stress of 1-4 GPa.

7. The nozzle of claim 1, wherein the refractory layer comprises an oxide of the one or more metallic elements.

8. The nozzle of claim 7, wherein the oxide is selected from the group consisting of chromium oxide, yttria stabilized zirconia, and titanium aluminum oxide.

9. The nozzle of claim 1, wherein the refractory layer comprises Ti 1-x-y Me y Al x N, wherein Me is selected from Group IVB-VIB of the periodic table, and x>0, y≥0 and 0.3≤x+y≤0.

9.

10. The nozzle of claim 9, wherein 0.4≤x+y≤0.

6.

11. The nozzle of claim 1, further comprising a second body disposed in the central bore, wherein a channel is formed between the first body and the second body.

12. The nozzle of claim 11, further comprising an additional body arranged in the central hole, wherein a channel is formed between the second body and the additional body.

13. The nozzle of claim 1, wherein the nozzle exhibits a continuous welding or cutting life of at least 5 hours.

14. The nozzle of claim 1, wherein the coating has a surface roughness of less than 500 nm.

15. A method of welding or cutting, the method comprising: Providing an arc welding torch including a nozzle, the nozzle comprising a first body, the first body including a central bore and an outer surface; and an electrically insulating coating adhered to the outer surface by physical vapor deposition (PVD) or chemical vapor deposition (CVD); the coating comprising a refractory layer comprising one or more metallic elements selected from the group consisting of aluminum, silicon, and metallic elements of Groups IIIB-VIIIB of the Periodic Table; and one or more non-metallic elements selected from Groups IIIA, IVA, VA, and VIA of the Periodic Table; and The arc welding torch is used to weld or cut metal or alloy workpieces.

16. The method of claim 15, wherein the continuous welding or cutting life of the nozzle is twice the life of an uncoated nozzle. 17 . The method of claim 15 , wherein the fire-resistant layer has a thickness of 1 μm to 10 μm.

18. The method of claim 15, wherein the fire-resistant layer has a critical load (L c ).

19. The method of claim 15, wherein the fire-resistant layer has a critical load (L c ).

20. The method of claim 15, wherein the refractory layer has a compressive residual stress of at least 2 GPa.

21. The method of claim 15, wherein the refractory layer has a compressive residual stress of 1-4 GPa.

22. The method of claim 15, wherein the refractory layer comprises an oxide of the one or more metallic elements.

23. The method of claim 22, wherein the oxide is selected from the group consisting of chromium oxide, yttria-stabilized zirconium oxide, and titanium aluminum oxide.

24. The method of claim 15, wherein the refractory layer comprises Ti 1-x-y Me y Al x N, wherein it is selected from Groups IVB-VIB of the periodic table, and x>0, y≥0 and 0.3≤x+y≤0.

9.

25. The method of claim 24, wherein 0.4≤x+y≤0.

6.

26. The method of claim 15, wherein the nozzle further comprises a second body disposed in the central bore, wherein a channel is formed between the first body and the second body.

27. A nozzle for an arc welding torch, the nozzle comprising: a first body comprising a central hole and an outer surface; as well as An electrically insulating coating adhered to the outer surface by thermal spraying, the coating comprising a refractory layer comprising one or more metallic elements selected from the group consisting of aluminum, silicon, and metallic elements of Groups IIIB-VIIIB of the Periodic Table; and one or more non-metallic elements selected from Groups IIIA, IVA, VA, and VIA of the Periodic Table.

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