Electrode wire and method for manufacturing the same

Abstract

An electrode wire (2) suitable for use as an electrode wire for electric food processing, the electrode wire comprising: - A metal core (10) extending along the longitudinal axis; - A coating (12) on the metal core having a mass of zinc oxide per unit area exceeding 0.5 g / m 2 and the zinc oxide is chlorine-enriched, i.e., the composition of the zinc oxide is (Zn ,O 2+ ,O 2- 1-x ,Cl - 2x ) where x is a mole fraction of 0.01 to 0.25.

Description

[Technical Field] 【0001】 The present invention relates to an electrode wire suitable for use as an electrode wire in EDM (electrical discharge machining) processing, and to a method for manufacturing an electrode wire. [Background technology] 【0002】 Electrode wires are used in EDM machines to cut metal or conductive materials. 【0003】 The well-known electrical discharge machining (EDM) method removes material from a conductive workpiece by generating sparks in the machining area between the workpiece and a conductive electrode wire. The electrode wire extends continuously in the direction of its length near the workpiece, is held by a guide, and gradually moves laterally toward the workpiece by the lateral translation of the wire guide or the translation of the workpiece. 【0004】 A generator, connected to the electrode wire via electrical contact and separated from the workpiece, establishes a suitable potential difference between the electrode wire and the conductive workpiece being processed. The workpiece area between the electrode wire and the workpiece is immersed in a suitable dielectric fluid. The potential difference between the electrode wire and the workpiece generates sparks that gradually erode the workpiece and the electrode wire. The longitudinal movement of the electrode wire ensures that a sufficient wire diameter is always maintained to prevent wire breakage in the workpiece area. Lateral relative movement between the wire and the workpiece allows for cutting or surface treatment of the workpiece as needed. 【0005】 Particles detached from the electrode wire and workpiece by the spark are dispersed in a dielectric fluid and discharged there. 【0006】 Especially when performing small-radius angle cuts, in order to achieve machining accuracy, it is necessary to use a small-diameter wire with a large mechanical cutting load, apply tension in the machining area, and limit the vibration amplitude. 【0007】 Most modern EDM machines typically have a diameter of 0.25 mm and a cutting load of 700 N / mm². 2 ~1,000 N / mm 2 It is designed to use metal wire. 【0008】 When a spark is generated between the electrode wire and the workpiece, the surface of the electrode wire is rapidly heated to a very high temperature in a short time. As a result, the material of the surface layer of the electrode wire changes from solid to liquid or gas at the point of the spark, displaced on the surface of the electrode wire, and / or discharged into the dielectric fluid. The outer surface of the electrode wire affected by the spark is deformed, becoming a slightly concave, crater-like shape overall, and it can be seen that there are areas where the material has melted and then solidified again. 【0009】 The efficiency of spark erosion has been shown to depend heavily on the properties and surface morphology of the electrode wire's surface layer. Therefore, significant improvements in EDM efficiency have been achieved by using electrode wires that possess the following characteristics: - A metal core made of one or more metals or alloys, ensuring good current conductivity and good mechanical strength to withstand the mechanical tensile load of the wire, - One or more other metals or alloys, and / or specific surface shapes, such as coatings on fractured areas, to reliably improve EDM efficiency, for example, to accelerate erosion. 【0010】 For example, Japanese Patent Publication No. 2-6076 discloses creating an oxide layer on the surface of an electrode wire to speed up processing. Other prior art is known from U.S. Patent No. 8,378,247B2 and U.S. Patent Application No. 2022 / 212277A1. [Overview of the Initiative] [Problems that the invention aims to solve] 【0011】 The present invention aims to further improve the processing speed of electrode wires having a coating containing an oxide, particularly zinc oxide. [Means for solving the problem] 【0012】 The present invention is described in the appended claims. 【0013】 The present invention is presented merely as a non-limiting example and will be better understood by reading the following description made with reference to the drawings. [Brief explanation of the drawing] 【0014】 [Figure 1] This is a schematic diagram of the cross-section of an electrode wire. [Figure 2] Figure 1 is a flowchart of a first method for manufacturing electrode wires. [Figure 3] Figure 1 is a flowchart of a second method for manufacturing electrode wires. [Figure 4] Figure 1 is a flowchart of a third method for manufacturing electrode wires. [Figure 5] This is a schematic diagram of a cross-section of another electrode wire. [Figure 6] Figure 5 is a flowchart illustrating the method for manufacturing the electrode wire shown. [Modes for carrying out the invention] 【0015】 In these figures, the same reference numerals are used to refer to the same elements. Features and functions that are well known to those skilled in the art are not described in detail in the remainder of this specification. 【0016】 Chapter I provides definitions of specific terms. Chapter II describes detailed examples of embodiments with reference to figures. Chapter III then presents variations of these embodiments. Finally, Chapter IV explains the advantages of various embodiments. 【0017】 Chapter I Definitions and Terms The expression "element made of material A" or "element of material A" refers to an element in which material A constitutes at least 70% by mass, preferably at least 90% or 95% by mass of this element. 【0018】 A "copper-zinc alloy" is an alloy made entirely of copper and zinc, with unavoidable impurities removed. Copper-zinc alloys are also known as "brass." 【0019】 The term "phase" in copper-zinc alloys refers to the solid phase of a copper-zinc alloy that possesses a specific crystallographic structure. More precisely, phases in copper-zinc systems are distinguished from one another by the composition of the copper-zinc alloy and their distinctive crystallographic structure. This distinctive crystallographic structure allows the phases of a copper-zinc alloy to be distinguished from simple mixtures of fine copper and zinc particles that have the same overall composition. Typical phases of known copper-zinc alloys are alpha, beta, gamma, delta, epsilon, and eta. The distinctive crystallographic structure of a phase can be identified by various means. For example, optical micrographs or metallographic structures of polished samples will show different hues for each phase, provided the sample is properly etched. For example, to distinguish the gamma phase from the epsilon phase, the sample is etched with "Nital," which is a solution of 3% nitric acid diluted with ethanol. The gamma phase will appear gray if the zinc content is low, and brownish-gray if the zinc content is high. The epsilon phase will appear a darker brown. The gamma phase can also be distinguished from the epsilon phase by observing the sample with a scanning electron microscope using a backscattered electron detector. It is also possible to identify the phase of a sample by X-ray diffraction. In X-ray diffraction, the wire sample is placed under an incident X-ray beam of a specific wavelength. For example, the Kα line of copper with an average wavelength of 0.1541 nm is used. The intensity of the diffracted light is evaluated for each diffraction angle. The gamma phase has a known X-ray diffraction spectrum that differs from the X-ray diffraction spectra of other phases of the copper-zinc system, and from zinc oxide (ZnO), which is often found on wire surfaces. If a copper-zinc alloy is not crystallized in at least one of the following forms: alpha, beta, gamma, delta, epsilon, or eta phases, the copper-zinc alloy is amorphous, and the X-ray diffraction pattern shows flat elevations rather than prominent peaks. At a given temperature, each different phase of a copper-zinc alloy corresponds to a specific range of zinc concentration. The extent of each of these specific zinc concentration ranges varies with temperature. 【0020】 The elemental concentrations in a sample can be obtained by trace composition analysis, particularly by energy-dispersive X-ray spectroscopy (EDS or EDXS). Trace composition analysis is performed using a scanning electron microscope equipped with a spectroscopic probe. For example, an electron beam accelerated by a 20 kV electric field collides with the surface of a sample, causing the sample to emit X-rays. These X-rays have an energy spectrum characteristic of the composition of the sample surface to which the electron beam collides. The spectrum of X-rays emitted from the sample surface is measured using an energy-dispersive spectroscopy (EDS) or wavelength-selective spectrometry (WDS) probe. An algorithm is used to select the element to be analyzed (and thus eliminate the influence of impurities) and calculate the composition of the sample to which the electron beam collides, based on the measured spectrum. Note that due to the interaction between X-rays and matter, the volume analyzed by EDS (or WDS) is generally about 1 cubic micrometer. At the boundary between two regions with different compositions, average concentrations that do not actually exist in either region may be measured. To avoid this problem, the compositions shown are measured in areas larger than 1 cubic micrometer, and at points within these analytical areas that are far from the boundaries with other unanalyzed areas. 【0021】 The expression "the concentration of an element in a region is greater than X atoms" means that the average concentration of this element in this region is greater than X atoms (at%). The average concentration is obtained, for example, by measuring the concentration of this element at various locations within the region and then averaging these concentration measurements. The locations where measurements are taken are the points where the lowest concentration is expected, the points where the concentration is expected to be close to the average, and the points where the highest concentration is expected. The measurement locations are typically distributed along an axis passing through the axis of the electrode wire. 【0022】 The term "conductivity" refers to an electrical conductivity of 10 at 20°C. 6 Exceeding S / m, preferably 10 7 This refers to materials exceeding S / m. 【0023】 The longitudinal axis of a wire is the axis along which the wire primarily extends. 【0024】 The term "cut surface" refers to a cross-section of an electrode wire perpendicular to its longitudinal axis. 【0025】 The term "longitudinal section" refers to a cross-section of an electrode wire obtained along a plane containing the longitudinal axis. 【0026】 The term "layer" refers to the annular layer of electrode wire between the inner and outer circular boundaries at each cross-section of the electrode wire. These boundaries are not actually perfect circles. However, as a first approximation, this book treats these boundaries as circles. Both the inner and outer circular boundaries are centered on the axis of the electrode wire. The inner circular boundary is the boundary of the layer closest to the axis of the electrode wire. Conversely, the outer circular boundary is the boundary of the layer furthest from the axis of the electrode wire. Between these inner and outer circular boundaries, the chemical composition is substantially homogeneous. Conversely, the chemical composition changes abruptly at both the inner and outer circular boundaries. In particular, the change in composition when crossing these circular boundaries is much larger than the slight change in composition that can be observed within the layer. 【0027】 A “uniform” layer is a layer formed of material that extends continuously or nearly continuously around the wire axis and within the layer at the cross-section of the wire. Therefore, a uniform layer does not have a large number of radial fractures in the longitudinal cross-section of the wire that divide the layer into a large number of blocks that are separated from each other. A large number of radial fractures means that in the longitudinal cross-section, such radial fractures divide the layer into approximately a dozen blocks that are mechanically separated from each other, with a dozen or so radial fractures per millimeter of electrode wire. 【0028】 The term "broken layer" refers to a layer having a number of breaks that, in the longitudinal cross-section of the wire, divide the layer into a number of blocks separated from each other by a number of radial breaks. The composition of these blocks is different from the composition of the adjacent layer below the broken layer or the composition of the metal core directly below the broken layer. Most of the blocks of the broken layer are longer than the thickness of the broken layer. Here, most of the blocks of the broken layer are longer than 5 μm or 10 μm. In this book, the length and width of the block in the cut surface are respectively defined to be equal to the length and width of the rectangle of the smallest area that completely contains this block. 【0029】 "Radial break" is a break that mainly extends in the radial direction within the cut surface of the electrode wire. 【0030】 The term "surface layer" refers to the outermost layer of the electrode wire. This surface layer may have a thin film of residues such as residues of the stretching lubricant on the surface of the surface layer. The outer surface of this surface layer is thus integrated with the outer surface of the electrode wire when there is no thin film, or is separated from the outer surface of the electrode wire only by this thin film. 【0031】 "Ambient temperature" refers to a temperature of 15°C to 35°C, typically 25°C. 【0032】 The average thickness e of the zinc oxide surface layer is defined by the following relational expression (1). e=(m i -m f ) / (ρ×π×d×L) Here, - m i is the initial mass of the wire sample with the zinc oxide surface layer, - m f is the mass of the same wire sample after being immersed in a bath that completely dissolves the zinc oxide surface layer, - ρ is the volume density of zinc oxide regardless of whether it is chlorine-enriched or not. This density ρ is here equal to 5600 kg / m 3 and, - π is the ratio of the circumference of a circle to its diameter, - d is the initial diameter of the wire sample before immersion in a bath that completely dissolves the oxide layer. - L is the length of the wire sample, and - The symbol "×" is the symbol for scalar multiplication. 【0033】 The average thickness e is measured using, for example, the following procedure: 1) Using a sample of wire length L and diameter d, wind it into a coil with a diameter of approximately 5 cm. The length L is, for example, 12 m. The diameter d is often equal to 0.25 mm. 2) Rinse the sample with water, then dry it, and remove dust with compressed air. 3) The initial mass m of the sample i This is measured using a precision scale. 4) Next, immerse the sample in a stirred aqueous bath of 8% to 12% sulfuric acid at a temperature of 42°C to 48°C for 20 to 30 seconds. 5) Rinse the sample with water. 6) Dry the sample using a jet of compressed air. 7) Final mass m of the sample f This is measured using a precision scale. 8) The average thickness e of the sample is calculated using the above relational equation (1). Unless otherwise specified, in the remainder of this book, the term "thickness of the zinc oxide layer" refers only to the average thickness of the zinc oxide layer. 【0034】 q: Average amount of zinc oxide contained in the surface layer ZnO This is determined by the following relation (2). q ZnO =(m i -m f ) / (π×d×L) Initial mass m i and final mass m f For example, the quantity q is measured using the same procedure as described in the measurement of the thickness e of the zinc oxide surface layer. ZnO From this point forward, the unit will be g / m 2 It is represented by . Quantity q ZnO is g / m 2Since it is expressed as such, it is the mass per unit area. Therefore, in this book, "quantity q" is used. ZnO The term "mass per unit area q" ZnO " and " refer to the same thing. Unless otherwise specified, in the remainder of this book, the term "amount of zinc oxide" refers only to the average amount of zinc oxide calculated using relation (2). 【0035】 After immersing a wire in an aqueous solution of zinc chloride (ZnCl2), the average amount of this salt that precipitates on the surface of the wire is q. ZnCl2 This is determined by the following relation (3). q ZnCl2 = (C / (1+C)) × (m fCl -m iCl ) / (π×d×L) Here, - C is the concentration of zinc chloride in an aqueous solution, expressed in units of kg / l, and C is equal to the mass of zinc chloride dissolved in 1 liter of water, expressed in units of kg. - m fCl This is the final mass of the wire sample, obtained by immersing the wire in an aqueous solution of this salt, which precipitates zinc chloride on the surface. - m iCl This is the initial mass of the same wire sample before immersion in zinc chloride solution. - π is the ratio of a circle's circumference to its diameter, - d is the initial diameter of the wire sample before immersion in the zinc chloride solution. - L is the length of the wire sample. 【0036】 average quantity q ZnCl2 This can be measured using, for example, the following method: 1) Using a sample of wire length L and diameter d, wind it onto a coil with a diameter of approximately 5 cm. The length L is, for example, 12 m. 2) Rinse the sample with water, then dry it, and remove dust with compressed air. 3) The initial mass m of the sample iCl This is measured using a precision scale. 4) The sample is then immersed in an aqueous zinc chloride solution to precipitate zinc chloride on its surface. 5) Drain the sample and remove any remaining solution droplets. Do not dry the sample as zinc chloride is highly hygroscopic. 6) Final mass m of the sample fCl This is measured using a precision scale. 8) Average quantity q ZnCl2 This is calculated using the above relational equation (3). quantity q ZnCl2 From this point forward, the unit will be g / m 2 It is expressed as follows. Unless otherwise specified, in the remainder of this book, the term "amount of zinc chloride deposited on the wire" refers only to the average amount of zinc chloride calculated using relation (3). 【0037】 Chapter II: Examples of Implementation Forms Figure 1 shows the EDM processing electrode wire 2 described in the introduction to this book. 【0038】 Electrode wire 2 is rated at 400 N / mm² for this purpose. 2 or 700 N / mm 2 It exceeds 1100 N / mm², generally speaking. 2 It has a breaking load of less than . Wire 2 extends along a longitudinal axis 4. Axis 4 is perpendicular to the plane of paper. The length of wire 2 is greater than 1 m, typically greater than 10 m or 50 m. 【0039】 The wire 2 has an outer surface 6 that is directly exposed to sparks when a workpiece is machined using electrical discharge machining (EDM) with this wire. The outer surface 6 is cylindrical and extends along the axis 4. The curve, which is the directrix of surface 6, is mainly a circle centered on the axis 4. Therefore, the cross-section of the wire 2 is circular. The outer diameter D2 of the wire 2 is typically 50 μm to 1 mm, and quite often 70 μm to 400 μm. Here, the diameter D2 is 0.25 mm. 【0040】 In this embodiment, wire 2 comprises the following: - A central core 10 made of conductive material, and - Coating 12 applied directly to core 10. 【0041】 The function of core 10 is to secure the majority of the breaking load on wire 2 on its own. Core 10 also ensures the conductivity of wire 2. For this purpose, core 10 is made of a conductive material. Core 10 is typically made of metal or a metal alloy. 【0042】 The core 10 has a mainly cylindrical circumferential surface 14 extending along the axis 4. This circumferential surface 14 is made of a copper-zinc alloy. In this example, the core 10 is made entirely of a copper-zinc alloy. For example, the single copper-zinc alloy of the core 10 is an α-phase copper-zinc alloy, or a copper-zinc alloy formed from a mixture of α and β phases. The core 10 does not have a central portion of a single-phase copper-zinc alloy covered with a layer of another phase copper-zinc alloy. The zinc concentration of the core 10 is typically greater than 20 atomic percent, preferably 36 atomic percent or more, or 40 atomic percent or more. The zinc concentration of the core 10 is typically less than 42 atomic percent. 【0043】 Coating 12 is designed to improve machining speed, and consequently, the erosion efficiency of the electrode wire and / or the surface quality of the part obtained after EDM machining. The lower the roughness, the better the quality of the EDM-machined surface. 【0044】 Coating 12 is 0.5 g / m for this purpose. 2 or 1 g / m 2 It contains an amount of zinc oxide exceeding [a certain value]. The amount of zinc oxide is 3 g / m². 2 or 5g / m 2 It may exceed this amount. The amount of zinc oxide in coating 12 is approximately 100 g / m². 2 or 50g / m 2 It is less than 10 g / m², and in many cases 10 g / m² 2 It is less than. 【0045】 In this embodiment, layer 12 is essentially made of zinc oxide. However, in some places, brass spikes may penetrate layer 12. These brass spikes form projections on the circumferential surface 14 of core 10 that penetrate layer 12. These brass spikes, together with core 10, form a single block of material. 【0046】 The zinc oxide contained in coating 12 is, more precisely, chemically formulated (Zn 2+ ,O 2- 1-x ,Cl - 2x ) is chlorine-enriched zinc oxide, where x is a mole fraction of 0.01-0.15, 0.01-0.2, or 0.01-0.25. A mole fraction x greater than 0.02 or 0.03 is preferable. A mole fraction x less than or equal to 0.2 or 0.13 is also preferable. The chlorine-enriched zinc oxide may be partially hydrated or unhydrated. Analysis by energy-dispersive spectroscopy (EDS) or wavelength-selective spectroscopy (WDS) yields essentially the same results for chlorine-enriched zinc oxide, regardless of whether it is hydrated or not. The composition of chlorine-enriched zinc oxide is shown hereafter without considering water molecules. 【0047】 In this first embodiment, the coating 12 consists of a single layer of zinc oxide. Hereafter, the same reference numeral will be used to refer to both the coating 12 and the zinc oxide layer. Layer 12 is the surface layer of the electrode wire 2. 【0048】 The average thickness of layer 12 is very small compared to the diameter D2 of wire 2, i.e., less than 0.5% of the diameter D2, preferably less than 0.25% of the diameter D2. 【0049】 Average thickness e of layer 12 12 The wavelength is 100 nm to 522 nm, preferably 100 nm to 400 nm or 100 nm to 300 nm. 【0050】 Compositional analysis using XPS (X-ray Photoelectron Spectroscopy) spectra revealed that the zinc oxide in layer 12 has the following atomic percentage composition. - More than 90% consists of zinc, oxygen, and chlorine, and - The remainder consists of copper and various manufacturing residues. 【0051】 These compositional analyses did not consider the presence of water, carbon, and carbon compounds on the surface of layer 12. This carbon actually originates from the lubricant used during the wire drawing process. The analysis performed showed that the zinc oxide was consistent with zinc ore. 【0052】 Next, a first method for manufacturing wire 2 will be described with reference to Figure 2. 【0053】 To carry out this manufacturing method, typically, first the desired thickness e 12 Select a thickness between 100nm and 522nm. 12 For example, we set this to be equal to 200 nm. Next, we select a value for coefficient c1, which will be explained later, between 1.15 and 6. For example, we set coefficient c1 to be equal to 2 here. Finally, we select the diameter D0 as a function of the previously selected coefficient c1 and the desired final diameter D2, while adhering to the constraints stated in the following paragraphs. For example, we set the final diameter D2 to be equal to 0.25 mm. 【0054】 In step 80, a brass blank wire is first supplied. The blank wire is a brass wire with a diameter D0 of 1.15 × D2 to 6 × D2, preferably 2 × D2 to 6 × D2. In this example, the diameter D2 is equal to 0.25 mm, so the diameter D0 is 0.288 mm to 1.5 mm, preferably 0.5 mm to 1.5 mm. Here, the diameter D0 is 0.5 mm. 【0055】 The zinc concentration of this blank wire is selected as described above for core 10. Here, the zinc concentration of the blank wire is 40 atomic percent. The higher the zinc concentration, the better the performance of wire 2. 【0056】 In this embodiment, a blank wire of a desired diameter D0 is a standard diameter D ini This is obtained by stretching a brass wire to a desired diameter D0. ini For example, it is 1.25 mm. 【0057】 Next, in step 82, the blank wire is oxidized to obtain an oxide blank wire. The oxide blank wire has a zinc oxide layer directly on its circumferential surface. This zinc oxide layer completely covers the circumferential surface of the oxide blank wire. For this purpose, in step 82, the supplied blank wire is heat-treated in the presence of oxygen and chlorine. This heat treatment is carried out in an oxygen-containing gaseous medium at a pressure exceeding 50 kPa or 100 kPa. Here, this heat treatment is carried out simply in the Earth's atmosphere, i.e., in a gaseous medium containing more than 20 volume percent oxygen, at an ambient pressure of about 101 kPa. 【0058】 To ensure the presence of chlorine during heat treatment, the blank wire is immersed in a zinc chloride solution before the start of the heat treatment. The concentration of zinc chloride in the solution is 0.5 g / m on the outside of the blank wire. 2 or 1 g / m 2 Ensure the deposition of zinc chloride exceeding a certain amount. The amount of zinc chloride deposited on the outside of the blank wire is 5 g / m 2 or 10g / m 2It is preferable that the concentration exceeds 250 g / l. Here, the temperature of the zinc chloride aqueous solution is equal to room temperature, and the concentration of zinc chloride in the solution is equal to 250 g / l. Immerse the blank wire in this solution for more than 1 second. Here, the immersion time is 1 to 10 seconds, preferably 3 to 6 seconds. Stir the solution throughout the immersion time to ensure that the concentration of zinc chloride is uniform. Allow the zinc wire to pass through the zinc chloride aqueous solution at a speed of, for example, 2 m / s. After immersion in the zinc chloride solution, drain the blank wire to remove any remaining solution droplets on the surface, thereby avoiding localized excess zinc chloride on the outside of the blank wire. Under these conditions, the amount of zinc chloride ZnCl2 deposited on the outside of the blank wire is about 6 g / m 2 That is the case. 【0059】 The zinc chloride-coated blank wire is then wound onto a steel coil, and the steel coil is placed in a furnace under ambient pressure and subjected to heat treatment. Here, the furnace is not airtight, and air is circulated throughout the entire heat treatment process. 【0060】 Here, this heat treatment is configured to generate a layer of zinc oxide on the circumferential surface of the blank wire with an average thickness e0 of 115 nm to 600 nm. In fact, if the thickness e0 is less than 115 nm, a thickness of 100 nm or more will occur after the stretching step 84 described below. 12 It is impossible to obtain this. On the other hand, when the thickness e0 exceeds 600 nm, it was observed that the zinc oxide layer does not adhere sufficiently and peels off at least in some places during the stretching step 84. This partial peeling of the zinc oxide layer during the stretching step 84 is a waste of material that should be avoided or limited, as the peeled zinc oxide is not used in the wire 2 produced. 【0061】 The thickness e0 is the desired thickness of zinc oxide after drawing, within the range (115nm~600nm). 12The thickness e0 that produces the desired result is determined by a series of experiments testing multiple thicknesses e0 within this range. In particular, when determining the thickness e0, it must be kept in mind that even if the thickness e0 is still less than 600 nm, a certain percentage of the zinc oxide will peel off during the stretching stage. This percentage of zinc oxide is currently estimated to be as high as 45% or even 30%. It should be emphasized that the percentage of zinc oxide lost during the stretching process is still far less than the percentage lost when the thickness e0 is selected to be greater than 600 nm or 800 nm. In fact, when the thickness e0 is greater than 600 nm or 800 nm, the percentage of zinc oxide lost during stretching exceeds 60% or 75%. The thickness of e0 to be tested is typically (c1 × e 12 ~Min(1.8 × c1 × e 12 Preferably in the range of ,600)), (1.2 × c1 × e 12 ~Min(1.8 × c1 × e 12 In the range of ,600)), and in many cases (1.35 × c1 × e 12 ~Min(1.7 × c1 × e 12 Select within the range of ,600)), and here, - c1 is equal to the diameter reduction factor of the oxide blank wire in stretching step 84, and - Min(a,b) is a function that returns the minimum value between a and b. 【0062】 The reduction coefficient c1 is defined as the ratio D0 / D2. Therefore, the thickness e 12 If is equal to 200 nm and coefficient c1 is equal to 2, then the desired thickness e after stretching will be 12 The thickness e0 at which this can be obtained is typically 540 nm to 600 nm. 【0063】 The heat treatment parameter to be set is the furnace temperature T during heat treatment. four The temporal evolution of this process, and the total duration D of this heat treatment. four Therefore, to simplify the adjustment of heat treatment parameters, the temperature T four is, duration Dfour Select to be constant throughout. 【0064】 Temperature T four When the temperature T is in the range of 130°C to 260°C, the oxidation rate of zinc-coated brass has only a slight temperature dependence. The thickness e0 of the chloride-doped zinc oxide layer appears to increase as a function of the square root of time according to the following relational expression (4). 【0065】 【Equation】 Here, - K = 2.68×10 -19 m 2 / s, - t is the duration, - e0 ini is the thickness e0 at time t = 0, - "×" indicates the symbol of scalar multiplication. 【0066】 Using relational expression (4), it is possible to estimate the theoretical value D of the duration D required to obtain a given thickness e0. Subsequently, in order to obtain the exact value of the duration D that enables the desired thickness e0 to be accurately obtained, multiple trials using various values of the duration D selected near the theoretical value D may be required. The value of the duration D selected as a result of such tests is typically in the range of (0.8×D four ~1.2×D fourT ), in the range of (0.9×D four ~1.1×D fourT ), or in the range of (0.95×D four ~1.05×D four ). fourT ~1.2×D fourT ), in the range of (0.9×D fourT ~1.1×D fourT ), or in the range of (0.95×D fourT ~1.05×D fourT ). 【0067】 The duration D four is advantageously selected to be longer than 4 hours or 6 hours to ensure a uniform distribution of temperature throughout the coil. 【0068】 Duration D four Finally, remove the blank wire coil from the furnace. At this point, the blank wire is covered with a layer of zinc oxide e0 thick. The blank wire is therefore called "oxide blank wire". The coil is cooled after being removed from the furnace. Cooling typically involves exposing the coil to ambient air for the duration necessary to cool it to room temperature. This completes step 82. 【0069】 In step 82, the zinc present in the brass is consumed by oxidation. As a result, the zinc concentration in the brass core of the blank wire near the zinc oxide layer is generally lower than the zinc concentration in the brass near axis 4. 【0070】 Next, in step 84, the oxidized and cooled blank wire is cold-drawn to produce wire 2. "Cold-drawn" refers to the fact that the drawing step 84 is performed without heating the blank wire before reducing its diameter. During step 84, a diameter reduction factor c1 is used to reduce the diameter D0 of the blank wire to the desired diameter D2 of wire 2, i.e., a diameter of 0.25 mm. 【0071】 Here, in step 84, the oxide blank wire is stretched under the same conditions as those favorable for the unoxidized brass wire. Diameter reduction is achieved by sequentially passing the oxide blank wire through a series of dies that shorten the diameter, so that the diameter of the oxide blank wire is gradually reduced until it reaches the desired diameter D2. For example, dies with elongation rates of 15% to 22% are used. A water-soluble lubricant is used to stretch the oxide blank wire. Here, the lubricant is, for example, an aqueous solution containing a water-soluble lubricant. 【0072】 This stretching process makes it possible to create a brass tip that penetrates layer 12. 【0073】 After step 84, once the diameter D2 is reached, in-line stress relief annealing is performed before winding. This stress relief annealing minimizes residual stress in wire 2, resulting in the wire being nearly straight when suspended vertically for 1 meter from the top end. This makes it easier to insert the electrode wire into the processing machine. This stress relief annealing does not alter the structure of wire 2 and has little effect on the wire's tensile strength. The stress relief annealing temperature is typically 250°C to 450°C, and the duration is less than one-tenth of a second. 【0074】 In step 82, the temperature T four The stress is low enough that the brass does not recrystallize under the influence of heat treatment, and as a result, the breaking load of the oxide blank wire is 700 N / mm². 2 It should be emphasized that it is larger. The coefficient c1 can therefore be made smaller as desired. On the other hand, to increase the cutting load of the oxide blank wire, the coefficient c1 should be selected to be 1.3 or 1.6 or greater. The coefficient c1 is the thickness e 12 It is also preferable that it be less than 6, so that when it is equal to 100 nm, the thickness e0 is still less than 600 nm. 【0075】 To demonstrate the advantages of electrode wires with a chlorine-enriched zinc oxide surface layer, the following tests were performed. A baseline EDM machining job was defined. The job involved cutting a punch from a 50 mm high steel piece with the guide surface positioned less than 0.2 mm from the workpiece. The cutting was performed on a CUT200MS machine sold by GF Machining Solutions. The cutting was performed in three machining passes using techniques adapted for brass. The movement speed of the workpiece relative to the electrode wire during each pass was adapted to cut the punch as quickly as possible with the same final surface finish. Here, this final surface finish corresponds to a roughness of Ra 0.6 μm. More precisely, in the tests performed, only the movement speed of the workpiece relative to the electrode wire in the first and second passes was adapted depending on the wire used. The movement speed of the workpiece relative to the electrode wire in the third pass was the same in all tests performed. 【0076】 The first wire was generated using the manufacturing method shown in FIG. 2. Subsequently, the second wire was manufactured using exactly the same manufacturing method as that used to obtain the first wire, except that the step of immersing the blank wire in the zinc chloride solution in step 82 was omitted. As a result, the heat treatment used to manufacture this second wire was carried out in the absence of chlorine. As a result, the thickness of the oxide layer of the second wire is different from the thickness e of the first wire. 12 It is different. 【0077】 Using the first wire and the second wire, the punching time was measured. The amount of zinc oxide in the first wire and the second wire was also measured. In order to eliminate the difference in processing speed that can only be explained by the fact that the thicknesses of the zinc oxide layers of the first wire and the second wire are different, for each wire, the processing efficiency E defined by the following relational expression was calculated. E = G / q ZnO Here, G and q ZnO are the measured time gain and the measured amount of zinc oxide of that wire, respectively. The time gain G is calculated using the following relational expression. G = 1 - (t u / t ref ) Here, - t u is the measured processing time, - t ref is the processing time required to perform the same processing on the same punch, but a brass wire containing 40 atomic% zinc and not coated is used. 【0078】 It was found that the processing efficiency of the first wire is 1.64 times higher than that of the second wire. This indicates that the first wire processes faster than the same wire in which zinc oxide is not chlorine-enriched. 【0079】 Figure 3 shows a second method for manufacturing wire 2. The method shown in Figure 3 is identical to the method shown in Figure 2, except that step 80 is replaced with step 90 and the final stretching step 84 is omitted. 【0080】 Step 90 is when the diameter of the supplied brass blank wire D0 is D2-e 12 This is identical to step 80, except that it is equal to the following: Then in step 82, the thickness e0 is equal to the thickness e 12 Select such that it is equal to . Thus, after step 82, wire 2 with diameter D2 is directly obtained without the need for a stretching step to reduce the diameter of the oxide blank wire. 【0081】 In this second method, the temperature of the blank wire does not exceed 250°C or 200°C during the oxidation step 82, so step 84 can be omitted, and as a result, even without the final stretching, the breaking load is still 700 N / mm². 2 This exceeds. In this second manufacturing method, since there is no final stretching, the thickness e0 can be selected to exceed 522 nm or 600 nm, and the thickness e 12 This makes it possible to generate wire 2 exceeding 522nm or 600nm. 【0082】 Figure 4 shows a third method for producing wire 2. This method is similar to the previously described method, except that the oxidation of zinc and enrichment of chlorine are not carried out simultaneously. 【0083】 This method begins with step 92, which involves supplying a blank wire. Step 92 is identical to step 80, except that the diameter D0 is 1.3 × D2 to 6 × D2. 【0084】 Next, in step 94, the blank wire is oxidized to obtain an oxidized blank wire. This step 94 is identical to step 82, except that the heat treatment is carried out in the absence of chlorine. To achieve this, the blank wire is not immersed in an aqueous zinc chloride solution. Because there is no chlorine, the oxidation rate of zinc in step 94 is slower. In this case, the values ​​of the parameters k and Q in relation (4) are 2.418 × 10⁻⁶, respectively. -7 m 2 It is estimated to be equal to / second and 152 kJ / mol. Acceptable D four To compensate for this slower oxidation rate while maintaining the duration, temperature T four The temperature should generally be selected between 400°C and 500°C. 【0085】 At the end of step 94, the zinc oxide in the oxide blank wire is not enriched with chlorine. 【0086】 Once step 94 is complete, the oxidized and cooled blank wire is stretched to the desired diameter D2 in step 96. Step 96 is, for example, identical to step 84. 【0087】 Either before or after step 96, the zinc oxide is enriched with chlorine in step 98. In Figure 4, step 98 is shown to be performed after step 96. In either case, step 98 is performed after the heat treatment, i.e., after the oxide blank wire has cooled to room temperature. 【0088】 In step 98, the zinc oxide produced in step 94 is brought into contact with a chlorine compound. The wire is immersed in a solution containing a chlorine compound, such as an aqueous zinc chloride solution at room temperature. Alternatively, the wire can be confined in a chamber containing chlorine gas. The time spent in contact with the chlorine compound is determined by the composition (Zn 2+ ,O 2- 1-x ,Cl - 2x To obtain chlorine-enriched zinc oxide, Cl -The anion is the initial composition (Zn 2+ ,O 2- O in zinc oxide 2- The interval is selected to be long enough to allow time for the anions to replace the ions, where x is a mole fraction of 0.01 to 0.25. Step 98 can be performed at room temperature. Step 98 can also be performed at a slightly higher temperature, such as 100°C to 200°C, although this is still lower than the temperature required for the recrystallization of the wire core 10. 【0089】 Hydrogen chloride (HCl) at room temperature is an example of a gaseous chlorine compound that can be used in step 98. Hydrogen chloride spontaneously occurs in a gaseous state above an aqueous solution of hydrochloric acid concentrated to about 10% at room temperature. Therefore, in step 98, the coil of wire oxidized in step 94 can be placed above such an aqueous solution of hydrochloric acid. After 24 hours, the zinc oxide in this wire is enriched with enough chlorine to obtain a processing rate greater than that of the same wire, except that it has not been exposed to hydrochloric acid vapor. 【0090】 Figure 5 shows a portion of the cross-section of electrode wire 100. This wire 100 is identical to wire 2, except that coating 12 has been replaced with coating 102. 【0091】 The coating 102, starting from the core 10 and moving outwards, comprises the following in succession: - Layer 104 of the beta-phase copper-zinc alloy, and - Surface fracture layer 106. 【0092】 Layer 106 consists of copper-zinc alloy blocks 110 separated from each other by fractures 112 that are partially filled with zinc oxide. In Figure 5, reference numerals 110 and 112 simply refer to some examples of blocks and fractures by illustration. The majority of these blocks, typically more than 90%, are essentially gamma-phase copper-zinc alloys. These gamma-phase blocks ultimately feature a thin layer of beta-phase on the surface of the block that is directly exposed to oxygen during the oxidation step 122 described below. This thin layer of beta-phase accounts for only a small proportion of the gamma-phase blocks. The thin layer of beta-phase corresponds to less than 20%, generally less than 10%, of the surface of the block in a cross-section or longitudinal section of a gamma-phase block longer than 5 μm, for example. In either case, the proportion of the beta phase within the gamma phase block is low, so the term "gamma phase block" refers to both a block composed entirely of gamma phase brass and a block composed essentially of gamma phase brass with a thin layer of beta phase brass on its surface. 【0093】 The zinc oxide contained in layer 106 is the same chlorine-enriched zinc oxide described above. 【0094】 Next, the method for manufacturing wire 100 will be explained with reference to Figure 6. 【0095】 In step 120, a blank wire is supplied. Here, this blank wire is produced using the process described in U.S. Patent No. 8378247B2. For example, first, a brass wire with a diameter of 1.25 mm is supplied. The zinc concentration of this wire is equal to 40 atomic percent. The brass wire is then electrolytically zinc coated to obtain a zinc-coated brass wire with a zinc layer 13.4 μm thick on the surface of the brass wire. This zinc-coated brass wire is then drawn to obtain a zinc-coated brass wire with a diameter of 0.512 mm and a pure zinc coating thickness of 5.5 μm. This wire is then heat-treated to form a layer of beta-phase copper-zinc alloy surrounded by a surface layer of gamma-phase copper-zinc alloy. For example, a coil of this drawn zinc-coated brass wire is initially placed in a furnace at room temperature. Then, the furnace temperature is changed over time as follows: - The temperature is increased to 300°C at a gradient of 300°C / hour, then - Maintain the furnace temperature at 300°C for 3 hours, then - Increase the furnace temperature to 330°C at a gradient of 20°C / hour, then - Maintain the furnace temperature at 330°C for 7 hours, then - The furnace temperature was lowered to 300°C at a gradient of 30°C / hour, then - Remove the coil from the furnace and allow it to cool to room temperature. 【0096】 Under these conditions, the thicknesses of the resulting beta phase layer and gamma phase layer are equal to 13 μm and 6 μm, respectively. A thin film of unenriched zinc oxide is also present on the surface of the gamma phase layer. The thickness of this zinc oxide film is 78 nm. 【0097】 Next, the heat-treated wire is drawn. This drawing process breaks the surface layer of the gamma phase, but the beta phase layer remains continuous. The break that separates the gamma phase block opens outwards. 【0098】 The blank wire thus produced has the following components in a continuous sequence, extending outward from the longitudinal axis: - Core 10, - Layer 104 made of beta-phase copper-zinc alloy, - A fracture layer similar to fracture layer 106, comprising a block of copper-zinc alloy in the gamma phase, and fractures that are not filled with zinc oxide or are only partially filled with it. Furthermore, if zinc oxide is present, it is not enriched with chlorine at this stage. 【0099】 Here, the heat-treated wire is stretched to a diameter of 0.355 mm. The thickness of layer 104 is 9 μm, the thickness of the fracture layer is 6 μm, and the thickness of the zinc oxide thin film is 52 nm. 【0100】 At the end of step 120, in step 122, the blank wire is oxidized to obtain an oxidized blank wire. For this purpose, in step 122, the supplied blank wire is heat-treated in the presence of oxygen and chlorine. Here, step 122 is carried out by applying the teachings presented in the specific case of oxidation step 82. For example, the blank wire is immersed in an aqueous zinc chloride solution for 10 seconds and then placed in a furnace at 120°C for 24 hours. In this oxidation step 122, some of the zinc present on the surface of the gamma phase block is consumed, which may result in the appearance of a thin layer of beta phase on part of the surface of these gamma phase blocks. 【0101】 At the end of step 122, a chlorine-enriched zinc oxide layer covers the fractured layer. In this example, the thickness of the chlorine-enriched zinc oxide layer is 1200 nm. 【0102】 Finally, in step 124, the oxide wire obtained in step 122 is stretched to the desired final diameter. Step 124 is performed under the same conditions as step 84. For example, the oxide wire is passed through four dies in sequence, reducing the diameter of the oxide wire sequentially to 0.324 mm, 0.296 mm, 0.270 mm, and finally to 0.25 mm. At the end of step 124, a stress relief annealing operation similar to or identical to that performed after step 84 is performed. 【0103】 During the final drawing, some of the zinc oxide on the surface of the oxide wire is pushed back into the fracture of the fracture layer. Thus, at the end of step 124, most of the fracture 112 between blocks 110 is filled with chlorine-enriched zinc oxide, at least partially. The amount of zinc oxide contained within the fracture 112 depends on the thickness of the zinc oxide layer produced in step 122. The greater the thickness of the zinc oxide layer produced in step 122, the more the fracture 112 is filled with chlorine-enriched zinc oxide. At the end of step 124, some of the outer surface of block 110 may still be covered with a layer of chlorine-enriched zinc oxide. The outer surface of block 110 is the outside of such blocks, i.e., the surface facing away from the longitudinal axis of the wire. In the specific case of the manufacturing method detailed here, the thickness of the chlorine-enriched zinc oxide layer obtained after this final drawing is equal to 500 nm. 【0104】 The processing speed of wire 100 was compared to that of a reference wire manufactured using the same manufacturing method, except that immersion in a zinc chloride aqueous solution was omitted. It was observed that the processing speed of wire 100 was 1.1 times greater than that of the reference wire. 【0105】 Chapter III: Transformation Forms Deformed form of electrode wire The metal core does not necessarily have to be made entirely of brass. Alternatively, the metal core may consist only of a brass surface layer, typically thicker than 5 μm or 10 μm. The core itself may be made of a different material, such as steel, copper, or another metal or metal alloy. 【0106】 The outer surface of coating 12 or 102 may be covered with a thin film of the lubricant used in stretching step 84 or 124. 【0107】 The thickness of the oxide layer 12 can also be greater than 461 nm. The thickness of the oxide layer 12 may be greater than, for example, 500 nm or 600 nm. 【0108】 Variations of manufacturing methods Alternatively, the blank wires supplied in steps 80, 90, and 92 may, for example, be zinc-free and comprise a metal core covered with a zinc surface layer. The zinc surface layer is often deposited on the metal core by electrolysis. In such cases, the electrolytic bath may contain chlorine compounds, thereby leaving residues of these chlorine compounds on the outside of the zinc layer when the zinc layer leaves the electrolytic bath. However, unless special measures are taken, the amount of these chlorine compounds residues from the electrolytic bath is too small to obtain chlorine-enriched zinc oxide with a mole fraction x greater than 0.01 after the oxidation step. Therefore, unless special measures are taken to retain a considerable amount of chlorine compounds from the electrolytic bath on the outside of the zinc layer, immersion in an aqueous zinc chloride solution cannot be omitted in this case. 【0109】 Alternatively, if a blank wire of the desired diameter D0 is commercially available, do not stretch the blank wire in step 80 before step 82. 【0110】 Other oxidation steps 82 or 122 are also possible. For example, the zinc chloride aqueous solution can be replaced with many other solutions containing chlorine compounds. For example, solutions containing hydrochloric acid or bleach are also suitable. Solutions containing NaCl may also be suitable. 【0111】 In another variation, instead of immersing the wire in a liquid solution containing chlorine, chlorine is deposited onto the wire by bringing it into contact with a gas containing chlorine compounds such as dichlor (Cl2). 【0112】 Alternatively, instead of placing the entire spool of blank wire in the furnace, the blank wire is unwound, passed through a heated tunnel, and then wound back onto the spool as it exits the tunnel. The temperature inside the tunnel is T four This is equivalent to heating the blank wire in sections one after another at temperature T fourHeat until . Therefore, the problem of the time required to obtain a uniform temperature throughout the entire coil of blank wire is eliminated. In this case, a higher temperature T four and very short duration D four It is possible to use this. For example, when using a heated tunnel, the temperature value T four The temperature can be higher than 300°C or 400°C. The speed at which the blank wire passes through the tunnel is, in this case, the duration D during which a portion of the blank wire remains inside the tunnel. four However, it is adjusted to enable the realization of the desired thickness e0. 【0113】 Even within the scope of the methods shown in Figure 2, thicknesses exceeding 522 nm e 12 To obtain this, the thickness e0 can be selected to be greater than 600 nm or 800 nm. 【0114】 Oxidation step 82 can also be performed in a medium other than the Earth's atmosphere. For example, step 82 can be performed in a medium containing more than 20% or 30% by volume of oxygen, or conversely, in a medium where the oxygen content is drastically reduced but a sufficient amount of oxygen remains to oxidize the blank wire. 【0115】 In another variation of step 82, temperature T four Duration D four It changes over time. For example, temperature T four for duration D four The temperature is continuously increased over a certain period. The manufacturing method is as follows, for example: A brass wire, 60% copper and 40% zinc, annealed and with a diameter of 1.25 mm, is supplied and then stretched to a diameter of 0.464 mm. The 0.464 mm diameter wire is then immersed for 5 seconds in a 252 g / l zinc chloride aqueous solution at 20°C (±5°C). After immersion in the zinc chloride aqueous solution, the wire is wound onto a steel spool and placed in a furnace under ambient pressure and atmospheric pressure. Temperature T four Next, the temperature is gradually increased from 20°C to 260°C at a rate of 10°C / hour. Duration D four Therefore, it is 24 hours. D fourNext, the wire is removed from the furnace and allowed to cool in air at room temperature. Then, using a die with an elongation of 15% to 22% and a lubricant consisting of an oil-in-water emulsion, the wire is stretched to a diameter of 0.25 mm at a temperature of 20°C to 80°C. Finally, the wire is stress-relieving annealed. The breaking load of the resulting wire is 900 N / mm². 2 It exceeds. 【0116】 In step 120, the supplied blank wire block can consist of gamma and epsilon phases. To achieve this, the heat treatment temperature used to form the beta and gamma phase layers is lowered, and instead, overlapping gamma and epsilon phase layers are formed. This is achieved, for example, by lowering the heat treatment temperature to 130°C to 160°C. The thickness of the epsilon phase layer is small enough that it breaks simultaneously with the gamma phase layer when stretched, so that the supplied wire has a fracture layer that essentially consists of both gamma and epsilon phase blocks, rather than just a block of gamma phase. 【0117】 In step 120, the block of blank wire can also be a block of the beta phase. To do this, for example, a blank wire containing a block of the gamma phase is first manufactured, and then heat-treated to convert the gamma phase block into a block of the beta phase. Such a method for manufacturing a wire containing essentially a block of the beta phase is described in U.S. Patent Application No. 2022212277A1. 【0118】 In another variant, step 124 is omitted. In this case, more than 50%, more than 70%, or more than 90% of the outer surface of the fractured layer block 110 is covered with a chlorine-enriched oxide layer. However, the fracture area does not necessarily need to be filled with chlorine-enriched zinc oxide. 【0119】 Oxidized blank wires can also be cooled in other ways. For example, the furnace can be switched off and the coil left inside the furnace until it reaches room temperature. 【0120】 In the simplified embodiment, stress relief annealing is omitted. 【0121】 Some of the variations described above can be combined into a single embodiment. 【0122】 Chapter IV Advantages of the Described Embodiments The fact that the coating contains chlorine-enriched zinc oxide improves processing speed compared to identical or nearly identical wires in which the zinc oxide is not chlorine-enriched. 【0123】 The fact that chlorine-enriched zinc oxide is mainly located within the fracture zone of the fracture layer not only improves the processing speed but also improves the electrical contact between this wire and the electrodes used when processing parts with this wire. 【0124】 The fact that the oxide layer thickness exceeds 100 nm improves the processing speed, enabling processing speeds that are particularly higher than those of electrode wires with a fractured gamma phase copper-zinc alloy coating, such as the electrode wire described in U.S. Patent No. 8,378,247,B2. 【0125】 The fact that the zinc oxide layer is less than 522 nm thick means that this zinc layer can be generated on a blank wire and then drawn to a final diameter D2 with minimal zinc oxide loss during the drawing process. 【0126】 The fact that the zinc oxide layer is formed directly on the circumferential surface of the metal core allows for the production of this zinc oxide layer simply by oxidizing the circumferential surface of the brass blank wire. Therefore, there is no need to deposit a zinc layer on the circumferential surface of the blank wire, as is the case when manufacturing the wire according to the teachings presented in, for example, U.S. Patent No. 8378247B2. It should be emphasized in particular that electrodeposition of a zinc layer onto a blank wire consumes far more energy than the heat treatment step. Thus, electrode wires in which the oxide layer is formed directly on the brass core can be manufactured in a simpler and more economical way. 【0127】 Chlorine-enriched zinc oxide is produced by the oxidation of zinc in the presence of chlorine, which improves the processing speed of the resulting electrode wire. 【0128】 The presence of chlorine in the heat treatment used for the oxidation of zinc accelerates the oxidation reaction. Thus, the duration and / or temperature of the heat treatment are shorter and / or lower than those required to obtain the same amount of zinc oxide in the absence of chlorine. Therefore, the presence of chlorine during oxidation speeds up the manufacturing process and / or lowers the heat treatment temperature. 【0129】 Obtaining the desired amount of zinc oxide by heat treatment not exceeding 250°C means that the wire's breaking load does not decrease during this heat treatment. As a result, it is no longer necessary to perform an additional stretching step with a high c1 coefficient to bring the oxide blank wire obtained after this heat treatment to an acceptable breaking load. In addition, this method allows for a reduction in the thickness of the oxide layer e 12 This makes the manufacturing of electrode wires exceeding 522nm or 600nm easier and more efficient. 【0130】 First, zinc is oxidized in the absence of chlorine, and then this unenriched zinc oxide is converted into chlorine-enriched zinc oxide. This allows for chlorine enrichment to be achieved with little to no heating, i.e., at room temperature.

Claims

[Claim 1] An electrode wire (2, 100) suitable for use as an electrode wire for electrolytic corrosion processing, wherein the electrode wire is - A metal core (10) extending along the longitudinal axis, - The mass of zinc oxide per unit area on the metal core is 0.5 g / m². ２ Coatings exceeding (12, 102) and The zinc oxide is enriched with chlorine, that is, the composition of the zinc oxide is (Zn ２＋ , O ２－ １－ｘ , Cl － ２ｘ ) wherein x is a mole fraction of 0.01 to 0.25, characterized in that, electrode wire (2, 100). [Claim 2] - The coating comprises a fractured layer (106) having a copper-zinc alloy block (110) and a fractured portion (112) that separates the copper-zinc alloy blocks from each other and separates them from adjacent layers. - The majority of the fractured portion (112) is filled with chlorine-enriched zinc oxide, The electrode wire according to claim 1. [Claim 3] - The coating comprises a fracture layer having a copper-zinc alloy block (110) and a fracture portion (112) that separates the copper-zinc alloy blocks from each other. The composition of the copper-zinc alloy block is different from the composition of the adjacent layer below the fracture layer, or the composition of the metal core directly below the fracture layer. - Chlorine-enriched zinc oxide covers at least 50% of the surface area of ​​the block surface facing outwards. The electrode wire according to claim 1 or 2. [Claim 4] The electrode wire according to claim 3 or 4, wherein the majority of the copper-zinc alloy block is a gamma-phase copper-zinc alloy block (110). [Claim 5] The electrode wire according to claim 1, wherein the coating (12) comprises a chlorine-enriched zinc oxide layer having an average thickness of more than 100 nm. [Claim 6] The electrode wire according to claim 5, wherein the average thickness of the chlorine-enriched zinc oxide layer (12) is less than 522 nm. [Claim 7] - The metal core (10) is made solely of a copper-zinc alloy. - The chlorine-enriched zinc oxide layer (12) is formed directly on the circumferential surface of the metal core. The electrode wire according to claim 5 or 6. [Claim 8] The electrode wire according to any one of claims 1 to 7, wherein the mole fraction x is 0.01 to 0.

15. [Claim 9] A method for manufacturing an electrode wire according to any one of claims 1 to 8, wherein the manufacturing method is - Steps (80, 90, 120) of supplying a blank wire whose outer circumference contains zinc or a zinc alloy, - After the above step, the mass of zinc oxide per unit area is 0.5 g / m². ２ In order to form a coating exceeding the limit, the steps include oxidizing the outer periphery of the blank wire (82, 122), Includes, A method for producing zinc oxide, characterized in that the step of oxidizing the outer periphery (82, 122) is carried out in the presence of a chlorine compound, thereby the zinc oxide obtained at the end of the oxidation step becoming chlorine-enriched zinc oxide. [Claim 10] The manufacturing method according to claim 9, wherein the step of oxidizing the outer periphery of the blank wire (82, 122) is performed by heat-treating the blank wire in the presence of oxygen and chlorine. [Claim 11] - The step of supplying the blank wire (80, 90) includes supplying a blank wire having a single copper-zinc alloy metal core, - The temperature at which the blank wire is heated during heat treatment is maintained at less than 250°C. The manufacturing method according to claim 10. [Claim 12] To ensure the presence of chlorine during the heat treatment, the blank wire is immersed in an aqueous zinc chloride solution before the start of the heat treatment, so that 0.5 g / m of the aqueous zinc chloride solution reaches the outer surface of the blank wire. ２ The manufacturing method according to claim 10 or 11, having a zinc chloride concentration that enables the precipitation of an amount exceeding a certain amount of zinc chloride. [Claim 13] A method for manufacturing an electrode wire according to any one of claims 1 to 8, wherein the manufacturing method is - Step (92) of supplying a blank wire whose outer circumference contains zinc or a zinc alloy, - After the step of supplying, when there is no chlorine compound, the mass of zinc oxide per unit area exceeds 0.5 g / m ２ a step (94) of oxidizing the outer peripheral portion of the blank wire to form a coating that exceeds, wherein the step of oxidizing the zinc oxide does not contain chlorine; and Includes, The manufacturing method is characterized in that, after the oxidation step, it includes a step (98) of enriching the zinc oxide with chlorine, and at the end of the oxidation step, the zinc oxide obtained is brought into contact with a chlorine compound to convert it into chlorine-enriched zinc oxide. [Claim 14] - The step of supplying the blank wire (120) includes supplying a blank wire having a fractured layer of copper-zinc alloy, wherein the outer surface of the blank wire forms the outer periphery of the blank wire. - The manufacturing method according to any one of claims 9 to 13, further comprising the step (124) of stretching the blank wire to push the chlorine-enriched zinc oxide into the fracture of the fracture, after the step of supplying the blank wire, once the chlorine-enriched zinc oxide is obtained on the outside of the fracture layer.

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