Welding electrode with functional coating

Abstract

The disclosed technology relates generally to welding electrodes, and more particularly to consumable welding electrodes having functional coatings. In one aspect, a welding electrode includes a core wire having a base metal composition and two or more coatings covering at least a portion of the core wire. The two or more coatings include a conductive coating that includes one or more conductive elements or compounds in addition to or different from copper (Cu). The two or more coatings additionally include an additional functional coating that includes one or more additional elements or compounds adapted to change the surface tension of a droplet formed by the welding electrode. In another aspect, a method of manufacturing a welding electrode includes providing a core wire having a base metal composition and forming two or more coatings layers.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 261,462, filed September 21, 2021, entitled “WELDING ELECTRODE WITH FUNCTIONALCOATINGS”, the contents of which are hereby incorporated by reference in their entirety. background Technical Field

[0004] The disclosed technology generally relates to welding electrodes, and more particularly to consumable welding electrodes having a functional coating on a core wire. Background Technology

[0006] Various welding techniques utilize consumable welding electrodes that serve as the source of weld metal. For example, in metal arc welding, an arc is generated when a voltage is applied between a consumable welding electrode (which acts as one electrode moving toward the workpiece) and the workpiece (which acts as the other electrode). The arc melts the tip of the metal welding wire, thereby producing molten metal droplets that deposit onto the workpiece to form weld metal or weld beads.

[0007] The technical and economic demands on welding technologies continue to increase in complexity, with the need for greater manufacturing flexibility and higher mechanical properties coexisting. Furthermore, optimizing one performance parameter of the weld metal may compromise another. Some welding technologies aim to address these competing requirements by improving consumables (e.g., by improving the physical design and / or composition of consumable electrodes). The disclosed technology addresses the need for improved consumable welding electrodes with functional coatings. Summary of the Invention

[0008] In a first aspect, the welding electrode comprises a solid core welding wire having an iron (Fe)-based base metal composition and a conductive coating formed on the solid core welding wire. The conductive coating, in addition to copper (Cu) or otherwise, comprises one or more conductive elements or compounds. The welding electrode further comprises an additional functional coating formed on the conductive coating and comprising one or both of the element antimony (Sb) and one or more Sb oxides.

[0009] In a second aspect, the welding electrode comprises a solid core welding wire having an iron (Fe)-based base metal composition and two or more coatings covering at least a portion of the core welding wire. The two or more coatings include a conductive coating formed on the solid core welding wire, which, in addition to copper (Cu) or otherwise, includes one or more conductive elements or compounds. The two or more coatings further include an additional functional coating having a porous structure formed on the conductive coating and including antimony (Sb). Attached Figure Description

[0010] Figure 1 An arc welding system that can be used in conjunction with a consumable electrode according to embodiments disclosed herein is shown.

[0011] Figure 2 A welding process using consumable electrodes according to embodiments disclosed herein is illustrated.

[0012] Figure 3 A covered welding consumable electrode according to an embodiment is shown.

[0013] Figure 4A A flux-coated welding consumable electrode comprising two or more coatings is shown according to an embodiment.

[0014] Figure 4B A flux-coated consumable electrode comprising three or more coatings is shown according to an embodiment.

[0015] Figure 5 A method for manufacturing a flux-coated welding consumable electrode according to an embodiment is shown.

[0016] Figure 6A The weld metal formed using a conventional consumable electrode is shown.

[0017] Figure 6B The diagram illustrates weld metal formed using a consumable electrode with a functional coating according to an embodiment. Detailed Implementation

[0018] Some welding electrodes have two main components: a core wire or rod and a coating. The core comprises the matrix alloying elements of the weld metal. The coating can include a variety of materials that provide various functions. For example, coatings can be used to provide: protection of the weld metal, arc stabilization, various physical properties of the alloying elements in the weld metal, slag for fluxing, reduction of porosity in the weld metal, improved conductivity or insulation, environmental protection, lubrication of the feed, and aesthetics.

[0019] Some traditional solid welding wires have a copper-containing coating on their surface to enhance the conductivity and corrosion resistance of the wire and welding nozzle, as well as reduce friction with the feed hose or welding nozzle. However, during the welding process, some copper may undesirably melt into the weld joint. Copper contamination at the weld joint can lead to “copper cracking” or reduce the mechanical properties of the weld joint, especially impact toughness and elongation at low temperatures. Copper also oxidizes into copper particles that escape into the air, which are harmful to human health when inhaled. The production of copper-coated welding wire can also generate waste acid and environmental pollution. Therefore, there is a need for a coated welding wire that at least reduces or eliminates copper from the coating on the welding electrode while maintaining its functional benefits.

[0020] To address these and other needs, the embodiments disclosed herein relate to a welding electrode comprising a core wire having a base metal composition and two or more coatings covering at least a portion of the core wire. The two or more coatings comprise a conductive coating, which, in addition to copper (Cu) or otherwise, includes one or more conductive elements or compounds. The two or more coatings further comprise an additional functional coating comprising one or more additional elements or compounds (molten weld metal surface tension modifiers) adapted for altering the surface tension of droplets formed by the welding electrode.

[0021] Arc welding process for welding with electrodes having functional coatings

[0022] Arc welding is one of several fusion processes used to join metals. By applying intense heat, the metal at the joint between two parts is melted, causing direct or more usually mixing with intermediate molten filler metal.

[0023] An arc welding system 100 that can be used in conjunction with the embodiments disclosed herein is shown in Figure 1A power system 110, including an AC or DC power supply and controller, is connected to the workpiece 102 to be welded via a working cable 114 and to an electrode holder 118 that makes electrical contact with the welding electrode 106 via a "thermal" cable. An electric arc is generated in the gap between the workpiece 102 and the welding electrode 106 when the energized circuit contacts the electrode tip against the workpiece 102 and retracts but remains in close contact. The arc can be generated between the welding electrode 106 (which can be a consumable electrode acting as one electrode (e.g., the anode (+) in a DC power supply)) and the workpiece 102 (which acts as another electrode (e.g., the cathode (-) in a DC power supply)). After the arc is ignited, a plasma 108 is maintained containing neutral and ionized gas molecules, as well as neutral and charged clusters or droplets of the metal welding wire material vaporized by the arc. The welding electrode 106 is advanced toward the workpiece 102, and the molten droplets of the metal welding wire are deposited onto the workpiece, forming a weld bead or weld metal. The arc can generate temperatures up to approximately 6500°F at its tip. The heat melts both the workpiece 102 and the welding electrode 106, creating a pool of molten metal, sometimes referred to as an "arc crater." As the crater moves along the joint, it solidifies behind the electrode. Upon cooling and solidification, a metallurgical bond is formed. Because the joint is a mixture of metals, the final welded part can have mechanical properties comparable to or substantially the same as those of the metal in the workpiece 102, such as strength. This contrasts sharply with non-fusion bonding processes (e.g., brazing, soldering, etc.), in which the mechanical and physical properties of the base material at the joint may be incomparable to those of the workpiece 102.

[0024] At high temperatures, metals tend to react chemically with elements in the air—oxygen and nitrogen. When the molten metal in the weld pool comes into contact with air, oxides and nitrides may form, which can adversely affect the strength and toughness of the weld joint. Therefore, some arc welding processes provide means of covering the arc and weld pool with protective shielding from gases, vapors, and / or slag. This is called arc protection. This protection reduces or minimizes the contact between the molten metal and air. Protection can also improve the weld joint. An example is flux, which can include deoxidizers for the weld metal.

[0025] In welding, the electric arc not only provides the heat required to melt the electrode and base metal, but under certain conditions, it must also provide a means to transport the molten metal from the electrode tip to the workpiece. Several mechanisms exist for metal transfer. Examples include surface tension transfer and jet arcing. In surface tension transfer, molten metal droplets contact the molten metal pool and are drawn into it by surface tension. In jet arcing, droplets are ejected from the molten metal at the electrode tip via an electric pinch, propelling the droplets into the molten pool.

[0026] When electrode 106 is a consumable electrode as disclosed herein, the tip melts under the heat of the arc, and the molten droplet separates and is transported to workpiece 102 via the arc column. Arc welding in which the electrode according to the embodiments described herein is melted to become part of the weld joint is described as metallic arc welding. This is in contrast to carbon or tungsten (TIG) welding, in which no molten droplet is forced through the gap and reaches the workpiece. Filler metal melts from a separate electrode or wire into the joint. More heat generated by the arc is transferred to the weld pool via the consumable electrode. This results in higher thermal efficiency and a narrower heat-affected zone.

[0027] Arc welding can be performed using direct current (DC) or alternating current (AC) with electrodes that are either positive (DCEP) or negative (DCEN). The choice of current and polarity depends on the process, the type of electrode, the arc atmosphere, and the metal being welded.

[0028] In processes using consumable electrodes, the electrode or welding wire melts to provide additive metal to fill gaps, thereby forming a welded joint that joins two metal workpieces. Welding processes using consumable electrodes include shielded metal arc welding (SMAW), gas metal arc welding (GMAW) or metal inert gas (MIG) welding, flux-cored arc welding (FCAW), metal-cored arc welding (MCAW), and submerged arc welding (SAW). Welding processes using consumable welding electrodes can be performed in DC electrode positive (DCEP) mode, DC electrode negative (DCEN) mode, or AC mode. In DCEP mode, direct current is used, and the welding wire is connected to the positive terminal of the power supply, while the workpiece(s) or plates(s) to be welded are connected to the negative terminal; the reverse is true in DCEN mode. In AC mode, the welding wire and the workpiece(s) or plates(s) switch from positive to negative in a cycle according to frequency. The terminal used as the positive electrode can be called the anode, and the terminal used as the negative electrode can be called the cathode. The following describes various electrode-based welding processes that can be implemented using oxide-coated welding wire according to embodiments.

[0029] Figure 2A gas metal arc welding (GMAW) process 200, sometimes referred to as a metal inert gas (MIG) welding process, is illustrated and can be used in conjunction with the embodiments disclosed herein. The GMAW process uses a continuous solid wire electrode 106 for filler metal and an externally supplied gas (typically from a high-pressure cylinder) for shielding. The electrode 106 may be low-carbon steel and may be coated with a thin layer of coating according to various embodiments, which may include two or more coatings comprising a conductive coating and an additional functional coating adapted to modify the surface tension of the molten droplets formed by the welding electrode (a surface tension modifier for molten weld metal). When an arc 108 strikes between the electrode 106 and the workpiece 102, the surfaces of both the electrode 106 and the workpiece 102 evaporate to form metal spheres transferred to the surface of the workpiece 102, thereby forming a weld pool 204 comprising the metal of the coated electrode 106 and the metal of the workpiece 102. The welding machine can be set to DC positive polarity. A shielding gas, typically carbon dioxide or a mixture of carbon dioxide and argon, protects the molten metal from atmospheric influence. A protective gas flows through the welding torch and cable assembly and exits the torch nozzle along with the welding wire to protect and safeguard the molten weld pool. Molten metal, if exposed to the atmosphere, can be highly reactive to oxygen, nitrogen, and hydrogen from the atmosphere. According to various embodiments, welding electrodes configured for the various welding processes described above (e.g., GMAW) comprise a core wire having a base metal composition and two or more coatings covering at least a portion of the core wire. As described herein, these two or more coatings comprise a conductive coating, which, in addition to copper (Cu) or otherwise, comprises one or more conductive elements or compounds. These two or more coatings further comprise an additional functional coating. This additional functional coating comprises one or more additional elements or compounds adapted to modify the surface tension of the droplets formed by the welding electrode.

[0030] Figure 3 A welding consumable electrode 300 according to various embodiments is shown. Electrode 300 comprises a core wire 304 and a coating 308. The core wire 304 may comprise a suitable carbon steel, such as low-carbon steel for GMAW, coated with coating 308 to provide alloying elements to the resulting weld metal, as well as various additional non-alloying functionalities, as described herein. The chemical elements and compounds of the core wire 304 and coating 308 disclosed herein can be distinguished based on whether the constituent elements are incorporated as part of the alloy of the weld metal. Hereinafter, elements substantially incorporated into the resulting weld metal may be referred to as alloying elements, while elements substantially not incorporated into the resulting weld metal for other functions (such as slag or gas formation or arc stabilization) may be referred to as non-alloying elements.

[0031] Figure 4A and 4BElectrodes 400A and 400B, respectively, according to some other embodiments of flux-coated welding, are shown. Electrodes 400A and 400B comprise a core wire 304 and a coating 308, and in addition to comprising multiple coatings, electrodes 400A and 400B are designed to be compatible with... Figure 3 The electrode 300A shown is configured in a similar manner. As an example, electrode 400A includes two coatings 308, including a first coating 308A and a second coating 308B. Electrode 400B includes multiple coatings 308, including a first coating 308A, a second coating 308B, and a third coating 308C. Additionally, although not shown, multiple coatings according to other embodiments may include n coatings, including first to nth coatings.

[0032] As described above, the weld metal may include the solidified metal of the workpiece and the metal that can consume the electrode. Because the amount of dilution or concentration of elements in the weld metal due to the incorporation of the molten workpiece can vary significantly, unless otherwise specified, the weight percentages of various elements and compounds in the weld metal disclosed herein refer to those of the undiluted weld metal that would be obtained if no dilution or concentration had occurred from the workpiece.

[0033] Still referencing Figure 3 and 4A -4B, the core wire 304 comprises a carbon steel composition, for example, a low-carbon steel composition. The carbon steel composition according to various embodiments includes Fe and one or more of C, Cr, Ni, Mo, V, Cu, Mn, and Si at concentrations greater than impurity levels. In some embodiments, the core wire 304 comprises a low-alloy steel composition, including an alloying element content of about 1.5% to 5% by weight. Additional elements may be present, which can be present at impurity levels. As described herein, an impurity level refers to the weight percentage of elements that are not intentionally introduced but are still present, which is typically less than 0.05%. Impurities that are not intentionally added but are still present in the core wire 304 include S, P, Al, Cu, N, Cr, Ni, Mo, V, Nb, and Ti. The weight balance of the core wire 304 may be Fe.

[0034] Still refer to Figures 4A-4B Coating 308 includes a conductive coating and an additional functional coating. The conductive coating includes one or more conductive elements or compounds other than copper (Cu), and the additional functional coating includes one or more additional elements or compounds adapted to modify the surface tension of the droplets formed by the welding electrode. As described herein, electrode 400A ( Figure 4A The first and second coatings 308A and 308B or electrode 400B Figure 4BAny one of the first, second, and third coatings 308A, 308B, and 308C can be a conductive layer or an additional functional layer in any order. Therefore, although the conductive coating according to the embodiment may be referred to as the first coating 308A of electrodes 400A and 400B, which is the innermost coating of the plurality of coatings 308, it should be understood that the conductive coating may also be the second coating 308B of electrodes 400A and 400B, or the third coating 308C of electrode 400B. Similarly, although the additional functional coating according to the embodiment may be referred to as the first coating 308A of electrodes 400A and 400B, which is the innermost coating of the plurality of coatings 308, it should be understood that the additional functional coating may also be the second coating 308B of electrodes 400A and 400B, or the third coating 308C of electrode 400B.

[0035] conductive coating

[0036] According to various embodiments, the first, second, and third coatings are 308A, 308B, 308C ( Figure 4A Any one of (or 4B) is a conductive coating comprising one or more conductive elements or compounds selected from the group consisting of magnesium (Mg), aluminum (Al), zinc (Zn), tin (Sn), chromium (Cr), platinum (Pt), silver (Ag), graphite, graphene, graphene oxide, and titanium (Ti).

[0037] According to various embodiments, a conductive coating is used to provide electrodes 400A and 400B with considerable conductivity, such that a considerable amount of current (e.g., >10%, >30%, >50%, >70%, >90%, or values ​​within any range defined by these values) flows through the first coating 308A during welding. In some embodiments, the one or more conductive elements or compounds are present in an amount and form that results in welding electrodes 400A and 400B having lower resistance relative to the core wire 304 without conductive elements or compounds.

[0038] In some embodiments, the one or more conductive elements or compounds are present without Cu as part of the conductive coating or as part of any of the plurality of coatings 308. That is, in some embodiments, the one or more conductive elements or compounds can avoid the need to use Cu as part of the coating, for example, to provide the necessary conductivity, and Cu can be omitted from the plurality of coatings 308. In some other embodiments, the one or more conductive elements or compounds are present in addition to Cu as part of the conductive coating or as part of any of the plurality of coatings 308. That is, in some embodiments, the one or more conductive elements or compounds can supplement Cu as part of the same or different coatings, for example, to provide the necessary conductivity.

[0039] The one or more conductive elements or compounds can significantly reduce or eliminate the need for copper as part of the coating in conventional coated electrode welding wires. Therefore, according to embodiments, the one or more conductive elements or compounds can be present in the absence of Cu or in addition to Cu. When present in addition to Cu, the one or more conductive elements are present in an amount exceeding 50 at.%, 60 at.%, 70 at.%, 80 at.%, 90 at.%, or a value within any range defined by these values, of the combined total of the one or more conductive elements or compounds and Cu. Therefore, the reduced Cu content can advantageously reduce the adverse effects of copper cracking at the weld joint.

[0040] When present, Cu is present in amounts exceeding 0.0005 wt.%, 0.0010 wt.%, 0.0020 wt.%, 0.0050 wt.%, 0.010 wt.%, 0.020 wt.%, 0.050 wt.%, 0.10 wt.%, 0.20 wt.%, 0.5 wt.%, or any of these values ​​within a defined range, based on the weight of the welding wire.

[0041] Additional functional coatings

[0042] According to various embodiments, the first, second, and third coatings are 308A, 308B, 308C ( Figure 4A Either (or 4B) is an additional functional coating containing a surface tension modifier for molten weld metal, as described below.

[0043] Various productivity parameters, such as the travel speed used to form the weld metal, can be determined in part by the surface tension of the molten weld metal droplets. To provide the desired molten weld metal surface tension, according to some embodiments, an additional functional coating includes a molten weld metal surface tension modifier. The molten weld metal surface tension modifier includes one or more additional elements or compounds adapted to modify the surface tension of the molten weld metal droplets formed by the welding electrodes 400A, 400B. According to various embodiments, the one or more additional elements or compounds adapted to modify the surface tension are selected from the group consisting of cadmium (Cd), mercury (Hg), gallium (Ga), indium (In), germanium (Ge), tin (Sn), lead (Pb), phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi), sulfur (S), selenium (Se), tellurium (Te), and polonium (Po).

[0044] One or more additional elements or compounds adapted to alter the surface tension of the molten weld metal can change (e.g., reduce) the surface tension of the molten weld metal droplets, causing the droplets to separate from the electrode at a faster rate than those formed by a reference electrode without such additional elements or compounds. The size of the droplets can be related to the equilibrium contact angle of the droplets formed on the solidified weld metal or workpiece, as defined by a relationship known as the Young-Dupré equation. If the solid-gas interfacial energy between the molten weld metals is expressed by γ... SG This indicates that the solid-liquid interface energy is determined by γ. SL This indicates that the liquid-gas interfacial energy (i.e., surface tension) is determined by γ. LG This indicates that the equilibrium contact angle θ C These quantities are determined by the following Young's equation:

[0045] γ SG -γ SL -γ LG cosθ C =0

[0046] In other words, the contact angle is established by the balance between adhesive forces (the liquid that wants to maintain contact with the solid) and cohesive forces within the liquid (both internal cohesion and surface tension). An increase in the adhesive forces between the liquid and the solid, or a decrease in the cohesive forces within the liquid (surface tension), will result in greater wettability and a smaller contact angle. For greater travel speeds, lower surface tension may be advantageous because the molten weld metal reduces the droplet size and improves the wettability of the workpiece or the solidified weld metal. For example, the average droplet size formed by the electrode according to the embodiment can be reduced by 30%, 40%, 50%, 60%, or values ​​within the range defined by any of these values ​​for the addition of these elements. The surface tension of the droplet formed by the welding electrode is reduced by 10%, 20%, 30%, 40%, 50%, or more compared to a reference droplet formed by the same welding electrode under the same welding conditions except for the presence of surface tension modifying elements. The average droplet size and surface tension can be reduced, so that the travel speed of the weld metal formed using the welding electrode according to the embodiment can be 30%, 40%, 50%, 60% or more higher than the travel speed of the weld metal formed using the welding electrode without the one or more additional elements or compounds adapted to change the surface tension of the molten weld.

[0047] The inventors have discovered that one or more additional elements or compounds adapted to alter the surface tension of molten weld metal can synergistically and simultaneously reduce the amount of slag or residual oxide or silicate islands formed on the weld metal. Oxide islands can be difficult to remove and degrade the visual appearance of the weld metal. The relative ease of removing oxide or silicate islands can be related to the equilibrium contact angle of the oxide or silicate islands formed on the weld metal, as defined by a relationship known as Young's equation. If the solid-gas interfacial energy is expressed by g... SG This indicates that the solid-liquid interface energy can be determined by g SL This indicates that the liquid-gas interfacial energy (i.e., surface tension) is determined by g. LG This indicates that the equilibrium contact angle q C These quantities are also determined by Young's equation as defined above. That is, although the same equation can be applied, the relevant interface is the interface between the silicate island and the underlying weld metal.

[0048] According to an embodiment, the one or more additional elements or compounds adapted to change the surface tension of the molten weld metal exist in an amount and form such that the volume of the silica islands formed on the weld metal formed by the welding wire is reduced by at least 30%, 40%, 50%, 60% or more relative to the volume of the silica islands formed on the weld metal formed by the core wire without the one or more additional elements or compounds adapted to change the surface tension of the molten weld.

[0049] According to various embodiments, each of the one or more conductive elements or compounds and the additional elements or compounds is present in an amount exceeding 0.0005 wt.%, 0.0010 wt.%, 0.0020 wt.%, 0.0050 wt.%, 0.010 wt.%, 0.020 wt.%, 0.050 wt.%, 0.10 wt.%, 0.20 wt.%, 0.5 wt.%, 1.0 wt.%, 2.0 wt.%, 5.0 wt.%, or a value within any defined range of these values, based on the weight of the welding wire.

[0050] Therefore, the welding wire comprises a core wire with an iron or steel composition (e.g., low-carbon steel composition) including Fe and one or more conductive elements or compounds of C, Mn, Si, Ni, Mo, Cr, and V at concentrations greater than impurity levels, as well as additional elements or compounds. The core wire referred to herein is a solid welding wire with a substantially uniform composition.

[0051] refer to Figure 4BIn some embodiments, two of the first, second, and third coatings 308A, 308B, and 308C are configured as conductive coatings. For example, the first and third coatings 308A and 308C may be the same or different conductive coatings, and may be inserted by a second coating 308B arranged as an additional functional coating.

[0052] Also refer to Figure 4B In some other embodiments, two of the first, second, and third coatings 308A, 308B, and 308C are configured as additional functional coatings. For example, the first and third coatings 308A and 308C may be the same or different additional functional coatings, and may be inserted by a second coating 308B arranged as a conductive coating.

[0053] Reference Figure 3 and Figures 4A-4B According to various embodiments, the core wire 304 may have a diameter of 1 / 16 inch (1.6 mm), 3 / 32 inch (2.5 mm), 1 / 8 inch (3.2 mm), 5 / 32 inch (4.0 mm), or 3 / 16 inch (5.0 mm), or a diameter within any range defined by these values, such as 3.2 mm. The core wire 304 may have a length of 250 mm, 300 mm, 350 mm, 400 mm, 450 mm, or 500 mm, or a length within any range defined by these values. The coating 308 may have a thickness of 1-1.5 mm, 1.5-2.0 mm, 2.0-2.5 mm, or 2.5-3.0 mm, or a thickness within any range defined by these values, such as 1.2 mm. By way of example only, an electrode with a core wire diameter of 3.2 mm and a coating thickness of 1.2 mm can have an overall diameter of 5.6 mm; and an electrode with a core wire diameter of 4.0 mm and a coating thickness of 1.35 mm can have an overall diameter of 6.7 mm. According to various embodiments, the coating 308 can have a weight percentage of 10%-15%, 15%-20%, 20%-25%, 25%-30%, 30%-35%, 35%-40%, or any value within the range defined by these values, based on the total weight of the electrode 300.

[0054] In a specific embodiment, an additional functional coating 308B is formed on the conductive coating 308A. When the additional functional coating 308B includes a surface tension modifier for molten weld metal, it includes elemental antimony (Sb) and one or more Sb oxides, or both. The one or more Sb oxides may be antimony tetroxide (Sb₂O₄), antimony trioxide (Sb₂O₃), antimony pentoxide (Sb₂O₅), or antimony hexadecyloxide (Sb₆O₃). 13It exists in one or more forms of antimony oxides and yellow antimony oxides (Sb3O6(OH)). Substoichiometric oxides of these oxides are also possible.

[0055] The inventors have found that forming an additional functional coating 308B including Sb via electrochemical deposition is particularly advantageous for the various reasons described herein. The electrode structure described herein, comprising a solid core wire coated with two or more functional coatings, is particularly advantageous for electrodeposition because the underlying solid core wire 304 or conductive coating 308A can act as an effective electrode for the relevant electrochemical reactions. This contrasts with electrode formation, for example, when the core is formed from powder (e.g., in a metal core electrode), where the core may be discontinuous or insufficiently conductive.

[0056] The inventors have further discovered that forming an additional functional coating 308B comprising Sb by electrochemical deposition can be particularly advantageous because it provides a high degree of control over the composition at both the macroscopic and microscopic levels. In particular, electrodeposition allows the formation of elemental antimony (Sb) and one or more Sb oxides, or both. In one specific example, an additional functional coating comprising particles of Sb and one or more Sb oxides can be deposited by constant-current reduction of antimony tartrate. Using such electrodeposition techniques, composite films comprising elemental antimony (Sb) and / or one or more Sb oxides, or both, can be formed. The relative amounts of Sb and / or Sb oxides can be controlled such that the overall composition of the resulting Sb / Sb oxide mixture can have an Sb:O ratio of 0.1, 0.2, 0.5, 1, 2, 5, 10, or any of these values ​​within a range defined by these values.

[0057] In some embodiments, the resulting film may be a homogeneous mixture of elemental Sb and Sb oxide. In some other embodiments, the resulting additional functional coating 308B may include islands, domains, grains, or particles that may include any one or more of elemental Sb and / or Sb oxide. As an example, the relative amounts of elemental Sb and Sb oxide, for example, the relative amounts of elemental Sb particles and Sb oxide particles, can be controlled by controlling the local pH at the electrode / electrolyte interface. Intermediates of welding electrodes with solid core wire coated with a conductive coating (e.g., a Cu coating) can serve as electrodes in these electrochemical reactions. Without being bound by any theory, although Sb is thermodynamically stable at low pH, higher pH values ​​favor the formation of Sb₂O₃. Therefore, by controlling the pH at the electrode / electrolyte interface, the additional functional coating may have controlled amounts of Sb particles and one or more Sb oxide particles. Furthermore, depending on the initial pH at the electrode / electrolyte interface, the additional functional coating 308B can be controlled to have an initial nucleation layer that is predominantly or more enriched in one or more of elemental Sb and Sb oxide. Using these and other methods, the weight ratio of elemental Sb particles to Sb oxide particles can be controlled to 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or any value within a defined range of these values.

[0058] The inventors have further discovered that forming an additional functional coating 308B including Sb via electrochemical deposition can be particularly advantageous, providing control over the morphology of the additional functional coating. In particular, the inventors have found that forming the coating with submicron particles can be advantageous, providing a high degree of control over the morphology of the resulting coating at both the macroscopic and microscopic levels. The nucleation density can be controlled in the electrochemical deposition of elemental Sb and Sb oxides by controlling the surface conditions of the underlying conductive coating, for example, a Cu coating formed on a solid core wire. For example, by providing a rougher underlying surface, a higher density of nuclei can be obtained, resulting in a smaller average size of islands, domains, grains, or particles. The average size of the islands, domains, grains, or particles can be less than 1000 nm, 800 nm, 600 nm, 400 nm, 200 nm, 100 nm, 50 nm, 20 nm, 10 nm, or values ​​within any of these ranges.

[0059] Islands, domains, grains, or particles can have controlled shapes and average sizes and size distributions, resulting in a controlled porosity for the resulting functional coating 308B. Controlled porosity can be advantageous for a variety of reasons, including physical appearance, improved adhesion to the overcoat, and controlled exposure of the underlying material. For example, the porosity (defined as the ratio of empty volume to the total volume of the coating) can be controlled to 0.1, 0.2, 0.3, 0.4, 0.5, or any value within a range defined by these values.

[0060] Additionally, in some embodiments, the additional functional coating 308B may be discontinuous, sheet-like, or otherwise formed to partially cover the underlying solid core welding wire 304 or conductive coating 308A. Partial coverage can be beneficial in certain situations, for example, for optimizing the surface friction and travel speed of the welding wire. For example, when the underlying conductive coating 308A, such as a Cu coating, has considerably lower friction, partial exposure of the conductive coating 308A may be desirable. The surface coverage (defined as the ratio of the surface area of ​​the underlying material (e.g., conductive coating 308A) covered by the additional functional coating 308B to the total surface area of ​​the underlying material) can be controlled to 0.1, 0.2, 0.3, 0.4, 0.5, or values ​​within any range defined by these values.

[0061] The inventors have discovered that, in order to improve the surface tension reduction effect of Sb while reducing the possibility of Sb having a detrimental effect on the mechanical properties of the resulting weld metal, the welding wire can be advantageously configured such that a controlled amount of Sb becomes part of the weld metal. According to embodiments, the amount of Sb in the welding electrode alloyed with the weld metal can be less than 60%, 50%, 40%, 30%, or 20% of the total amount of Sb present in the welding wire, for example, 25%-60% of the total amount of Sb present in the welding wire. The relatively small amount of Sb incorporated into the weld metal can be attributed to various characteristics of the above-described additional functional coating 308B, including the presence of both elemental Sb and Sb oxide, which can be achieved by electrochemical deposition. For example, different amounts of Sb can be volatilized by controlling the ratio of elemental Sb to Sb oxide. Table 1 below shows the experimental atomic percentage of Sb in the experimentally manufactured welding wire and the detected atomic percentage of Sb in the resulting weld metal. As shown, 0.009%-0.024% Sb in the welding wire results in 0.004%-0.010% Sb in the resulting weld metal.

[0062] Table 1

[0063]

[0064]

[0065] Methods for manufacturing coated electrodes

[0066] Figure 5 A method 500 for forming two or more coatings on a core wire according to an embodiment is shown. Method 500 includes providing a core wire 304 510 having a base metal composition. Figure 4A , 4B Method 500 includes forming a first coating 308A 530 and conditioning the surface of the 520 core welding wire to prepare for the formation of two or more coatings. Figure 4A , 4B The first coating comprises a conductive coating (including one or more conductive elements or compounds other than copper (Cu) or different from copper) and an additional functional coating. After forming the first coating 308A at 530, method 500 proceeds to post-conditioning 540 of the surface of the first coating 308A. Method 500 further includes forming a second coating 308B at 550 comprising the conductive coating and another of the additional functional coatings. Figure 4A , 4B After forming the second coating 308B, method 500 proceeds to post-conditioning 560 of the surface of the second coating 308B.

[0067] In some embodiments, method 500 is optionally performed to form a third coating 308C (540). Figure 4B In some embodiments, the third coating 308C may be a second conductive coating comprising one or more conductive elements or compounds other than copper (Cu). In some other embodiments, the third coating 308C may be a second additional functional coating that is different from the first functional coating.

[0068] As described above, electrode 400A ( Figure 4A The first and second coatings 308A and 308B or electrode 400B Figure 4B Any one of the first, second, and third coatings 308A, 308B, and 308C can be arranged as a conductive coating or an additional functional coating in any order.

[0069] Method 500 can be performed in a production line including a loading station for providing 510-core welding wire, a surface conditioning station for conditioning 520-core welding wire, a drawing station, a first coating station for forming a first coating 530, a first post-conditioning station for post-conditioning the surface of the first coating 540, a second coating station for forming a second coating 550, a second post-conditioning station for post-conditioning the surface of the second coating 560, a third coating station for forming a third coating 570, and a third post-conditioning station for post-conditioning the surface of the third coating 580.

[0070] Providing 510 cored welding wire includes providing cored welding wire 304 containing the base metal composition described above (e.g., steel composition, such as low carbon steel composition). Figure 3 , 4A -4B). Adjusting the surface of the 520-core welding wire includes cleaning the surface of the core welding wire at the cleaning station. In one exemplary embodiment, the cleaning station uses a cleaning and / or coating agent to clean the outer surface of the material.

[0071] After cleaning, the material is moved to a drawing station. The drawing station includes at least one die. In one exemplary embodiment, the drawing station includes a series of dies, each having an opening progressively smaller than the preceding die. A lubricant (e.g., powdered lubricant) may be added to these dies to facilitate the passage of the core wire through them and reduce wear on the dies. As the core wire passes through the drawing station, the diameter of the material can be gradually reduced to a desired size through plastic deformation. In some embodiments, the drawing process uses drawing soap, which may be a stearate, such as calcium stearate, sodium stearate, etc. These soaps facilitate the drawing process. After the drawing step, the core wire may be further passed through an acid bath to further clean the introduced core wire and prepare it for the formation of one or more coatings thereon. After cleaning, the desired Ca range on the wire will allow the wire to be further used for coating. The Ca content can vary from 0.0005 wt% to 1 wt% of the wire to form an optimized surface for further coating.

[0072] After adjusting the surface of the 520-core welding wire, method 500 proceeds to forming the first coating 308A (530). Figure 4A , 4B The first coating comprises one of a conductive coating (including one or more conductive elements or compounds other than copper (Cu) or different from copper) and an additional functional coating (e.g., an Sb-containing coating as described herein).

[0073] In various embodiments, forming the first coating 530 includes, for example, wet coating in a wire plating bath comprising the desired coating formulation. The wet coating process can be performed via chemical / electrochemical or mechanical / physical methods. Chemical methods can be displacement reactions, sol-gel film methods, electroplating, or electroless plating, etc. In mechanical / physical methods, an adhesive is used to adhere the coating to the surface of the wire.

[0074] After forming the first coating 308A, method 500 proceeds to post-conditioning 540 of the surface of the first coating 308A. In some instances, post-conditioning 540 includes curing using, for example, in-line heating. In-line heating is achieved by conduction, convection, radiation, or Joule heating, etc. Heating can be electrical / resistance heating, induction heating, heating by flame or hot air, laser heating, plasma heating, etc.

[0075] Method 500 further includes forming a second coating 308B comprising another of a conductive coating and an additional functional coating. Figure 4A , 4B In various embodiments, forming the second coating 550 includes, for example, wet coating in a wire plating bath comprising the desired coating formulation. The wet coating process can be performed via chemical / electrochemical or mechanical / physical methods. Chemical methods can be displacement reactions, sol-gel film methods, electroplating, or electroless plating, etc. In mechanical / physical methods, an adhesive is used to adhere the coating to the surface of the wire.

[0076] When present, method 500 includes forming (multiple) additional coatings 308C. Figure 4B The process can be similar to forming the first and / or second coatings 308A and 308B of 530 and 550.

[0077] It should be understood that in some embodiments, one or both of the conductive coating and the additional functional coating contain a plurality of pores, wherein these pores are at least partially filled with a material different from that of the conductive coating and the additional functional coating having these pores. When present, having a porous structure can be beneficial for improving adhesion between different layers.

[0078] After forming the second coating 308B, method 500 proceeds to post-conditioning 560 of the surface of the second coating 308B. In some embodiments, post-conditioning 560 includes using a finishing / polishing mold. When the final coating contains a metallic coating such as a Cu coating, the polishing mold has effects such as smoothing the surface of the solder wire, removing excess copper, and making the solder wire appear uniform and glossy. The mold can be a polycrystalline diamond mold or a tungsten carbide mold.

[0079] Figure 6A The weld metal formed using a conventional consumable electrode is shown. Figure 6B The diagram illustrates weld metal formed using a consumable electrode with a functional coating according to an embodiment. Figure 6A and 6B The two consumable electrodes used to form the weld metal have the same composition, except for these functional coatings. Specifically, Figure 6B The weld metal shown is formed using an electrode with a conductive coating and an additional functional coating. The conductive coating includes one or more conductive elements, including copper (Cu). The additional functional coating is formed on the conductive coating and includes antimony (Sb) and one or more Sb oxides. (See above regarding...) Figure 4A As described, the weld metal formed using the consumable electrode according to the embodiment has a significantly reduced amount of silicate islands due to the increased contact angle between the silicate islands and the weld metal. For example, as shown, the surface area of ​​the covered weld metal has...

[0080] Unless the context explicitly requires it, throughout the specification and claims, the terms “comprise,” “comprising,” “include,” “including,” etc., shall be interpreted in an inclusive sense, rather than an exclusive or exhaustive one; that is, in the sense of “including but not limited to.” As commonly used herein, the term “connected” refers to two or more elements that can be directly connected or connected via one or more intermediate elements. Similarly, as commonly used herein, the term “connected” refers to two or more elements that can be directly connected or connected via one or more intermediate elements. Additionally, when used in this application, the terms “here,” “above,” “below,” and similar terms shall refer to the entire application and not any particular part of it. Where the context permits, the use of singular or plural terms in the above specific embodiments may also include either the plural or the singular, respectively. The term “or” refers to a list of two or more entries, and covers all of the following interpretations: any entry in the list, all entries in the list, and any combination of entries in the list.

[0081] Furthermore, unless otherwise specifically stated or otherwise understood within the context in which they are used, the conditional language used herein (among others, such as “can,” “could,” “might,” “may,” “eg,” “for example,” “such as,” etc.) is generally intended to convey that certain embodiments include certain features, elements, and / or steps, while other embodiments do not include certain features, elements, and / or steps. Therefore, this conditional language is not generally intended to imply that such features, elements, and / or statements are necessary in any one or more embodiments, or whether such features, elements, and / or statements are included in any particular embodiment or are to be performed in any particular embodiment.

[0082] While certain embodiments have been described, these embodiments are presented by way of example only and are not intended to limit the scope of this disclosure. In fact, the novel apparatuses, methods, and systems described herein can be implemented in a variety of other forms; furthermore, various omissions, substitutions, and changes can be made to the form of the methods and systems described herein without departing from the spirit of this disclosure. For example, although blocks are presented in a given arrangement, alternative embodiments may perform similar functions with different components and / or circuit topologies, and some blocks may be deleted, moved, added, subdivided, combined, and / or modified. Each of these blocks can be implemented in a variety of different ways. Any suitable combination of elements and functions of the different embodiments described above can be combined to provide further embodiments. The various features and processes described above can be implemented independently of each other or combined in various ways. All possible combinations and sub-combinations of the features of this disclosure are intended to fall within the scope of this disclosure.

Claims

1. A welding electrode comprising: Solid core welding wire composed of an iron (Fe)-based base metal; A conductive coating, formed on the solid core welding wire, and comprising one or more conductive elements or compounds other than copper (Cu), and An additional functional coating is formed on the conductive coating and includes one or both of the element antimony (Sb) and one or more Sb oxides, wherein... The additional functional coating comprises submicron particles containing the element Sb and one or more Sb oxides, and wherein the additional functional coating is a porous layer containing a plurality of pores formed between adjacent submicron particles.

2. The welding electrode as described in claim 1, wherein, Compared to a reference droplet formed from a reference welding electrode that is identical to the welding electrode except for the presence of Sb under the same welding conditions, the total amount of Sb in the welding electrode effectively reduces the surface tension of the droplet formed by the welding electrode by 10% or more.

3. The welding electrode as described in claim 2, wherein, The total amount of Sb is 0.0005% - 2% by weight of the welding electrode.

4. The welding electrode as described in claim 1, wherein, The submicron particles contain elemental Sb particles and Sb2O3 particles.

5. The welding electrode as described in claim 1, wherein, These holes expose the conductive coating underneath.

6. The welding electrode as described in claim 2, wherein, The welding electrode is configured to form weld metal at a travel speed 30% or more higher than that of the reference welding electrode used to form reference weld metal under the same welding conditions as the reference welding electrode, except in the presence of Sb or one or more Sb oxides.

7. The welding electrode as claimed in claim 1, wherein, The one or more conductive elements or compounds are selected from the group consisting of magnesium (Mg), aluminum (Al), zinc (Zn), tin (Sn), chromium (Cr), platinum (Pt), silver (Ag), graphite, graphene, graphene oxide, and titanium (Ti).

8. The welding electrode as described in claim 7, wherein, One or more conductive elements or compounds are present in the conductive coating in the absence of Cu.

9. The welding electrode as claimed in claim 7, wherein, In addition to Cu, the one or more conductive elements or compounds are present in an amount exceeding 90 atomic percent of the combined total of the one or more conductive elements or compounds and Cu.

10. The welding electrode as claimed in claim 3, wherein, The welding electrode is configured such that the weld metal formed using the welding electrode contains 25%-60% of the total amount of Sb present in the welding electrode.

11. A welding electrode comprising: A solid core welding wire composed of an iron (Fe)-based base metal; and Two or more coatings covering at least a portion of the solid core welding wire, wherein the two or more coatings comprise: A conductive coating, formed on the solid core welding wire, comprises one or more conductive elements or compounds other than copper (Cu) or different from copper, and An additional functional coating comprising antimony (Sb) having a porous structure and formed on the conductive coating, wherein the Sb is in the form of elemental Sb and one or more Sb oxides, and wherein the additional functional coating comprises submicron particles containing elemental Sb and the one or more Sb oxides.

12. The welding electrode as claimed in claim 11, wherein, Compared to the contact angle of a reference oxide island formed on a reference weld metal formed under the same welding conditions and by a reference welding electrode that is identical to the welding electrode except for the presence of Sb, the total amount of Sb present in the welding electrode is an amount that effectively increases the contact angle of the oxide island formed on the weld metal formed by the welding electrode by 10% or more.

13. The welding electrode as claimed in claim 12, wherein, The total amount of Sb in this welding electrode is 0.0005 wt% - 2 wt%.

14. The welding electrode as claimed in claim 11, wherein, These submicron particles contain elemental Sb particles and Sb2O3 particles.

15. The welding electrode as claimed in claim 11, wherein, These submicron particles partially cover the conductive coating, leaving portions of the conductive coating exposed between adjacent submicron particles.

16. The welding electrode as claimed in claim 11, wherein, The total amount of Sb exists in the welding electrode in such a quantity and form that the volume of the silica island formed on the welding metal formed by the welding electrode is at least 50% lower than the volume of the reference silica island formed on the reference welding metal formed under the same welding conditions using the same reference welding electrode except for the presence of Sb.

17. The welding electrode of claim 11, further comprising calcium (Ca) in the interface region between the core wire and the two or more coating layers, in an amount of 0.0005 wt.%-1 wt.% of the weight of the welding electrode.

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