A tungsten alloy wire, articles and methods of making

Abstract

The application discloses a tungsten alloy wire and an article and a preparation method thereof, and the tungsten alloy wire is composed of a tungsten alloy mother wire and a self-lubricating composite coating, wherein the self-lubricating composite coating is sequentially composed of a pre-plating layer and a composite coating from inside to outside. In one aspect, the tungsten alloy mother wire is etched by hydrofluoric acid, and meanwhile, a pre-plating bottom layer is added, so that the binding force between the electroplating layer and the tungsten alloy mother wire is enhanced. Meanwhile, the self-lubricating composite coating is prepared by adding solid lubricating particles into an electroplating solution, so that the die loss in the drawing process is effectively reduced, and the cost is saved. In another aspect, the pre-plating process of nickel sulfamate is changed, and impact nickel is used as the pre-plating bottom layer of the diamond wire, so that the binding force between the grinding composite coating and the diamond wire mother wire is improved, and the problems of wire breakage or silicon wafer scratch caused by the falling of the grinding composite coating during the cutting process of the diamond wire can be prevented.

Description

A tungsten alloy wire, its products and preparation method Technical Field

[0001] This invention belongs to the field of diamond wire technology, specifically relating to a tungsten alloy wire, its products, and a preparation method. Background Technology

[0002] Wire sawing is widely used in the photovoltaic, semiconductor, and LED industries for cutting hard and brittle materials such as monocrystalline silicon, polycrystalline silicon, and glass due to its advantages of low wear, low TTV (total volumetric TV line), and high cutting efficiency. Wire sawing methods are divided into free slurry cutting and bonded abrasive cutting. Free slurry cutting uses an exposed metal wire with a slurry containing silicon carbide abrasive, cutting through rolling and pressing. This method suffers from low cutting efficiency and environmental pollution caused by the slurry, and has been gradually replaced by bonded abrasive cutting. Bonded abrasive wire saws are further divided into electroplated diamond wire saws and resin-bonded diamond wire saws. Resin-bonded diamond wire saws suffer from weak bonding between the diamond abrasive and the wire core, leading to diamond detachment during cutting. Therefore, electroplated diamond wire saws are the mainstream product on the market.

[0003] Electroplated diamond wire saws are made by electroplating diamond onto a metal busbar. Depending on the type of busbar, they are divided into high-carbon steel diamond wire and tungsten alloy diamond wire. In order to reduce non-silicon costs and achieve grid parity in the photovoltaic industry, electroplated diamond wire is trending towards thinner wires. The theoretical limit for the diameter of high-carbon steel diamond wire is approximately 30µm. Tungsten alloy wire has advantages such as high strength, high temperature resistance, and corrosion resistance. Furthermore, tungsten alloy wire doped with rare earth elements has excellent processing performance, with a theoretical diameter limit of approximately 22µm, thus compensating for the shortcomings of carbon steel wire in terms of diameter, tensile strength, and corrosion resistance.

[0004] The traditional method for refining tungsten alloy wire involves spraying graphite emulsion onto the wire surface, followed by heating and drying. This forms a graphite layer with good lubrication properties, allowing the drawing process to continue. However, differences in raw material selection among manufacturers result in significant variations in graphite emulsion particle size, suspension properties, and viscosity. Furthermore, most domestic manufacturers use graphite powder with a particle size >3µm in their fine wire graphite emulsions. When the graphite powder particle size is too large, the lubricity of the graphite layer decreases when drawing 30-50µm fine wires, increasing die wear and affecting the yield of tungsten alloy wires. By using composite electroplating, a finely crystalline, robust metal lubricating layer containing solid lubricating particles is electroplated onto the surface of coarse-diameter tungsten alloy wires. This solves the problems of poor adhesion and excessively large graphite powder particle size associated with traditional graphite layers, reducing die wear and improving yield. However, tungsten metal is highly reactive; under oxygen-containing conditions, a dense, dark blue passivation film easily forms on the surface of the tungsten alloy wire. This passivation film exhibits high chemical stability. During electroplating, the presence of this passivation film often leads to weak adhesion between the plating metal and the tungsten alloy busbar. Furthermore, the fabrication of diamond wire saws using composite electroplating also faces the challenge of insufficient adhesion between the tungsten alloy substrate and the electroplated nickel layer when using nickel sulfamate plating solution. Therefore, it is necessary to select appropriate pretreatment methods and electroplating processes to address the adhesion issue of the plating layer on the tungsten substrate surface. Summary of the Invention

[0005] In order to overcome the shortcomings of existing technologies in terms of yield, mold wear, and coating adhesion of tungsten alloy busbars and diamond wires, this invention provides a tungsten alloy wire, its products, and a preparation method.

[0006] The first technical solution provided by this invention is: a tungsten alloy wire, which consists of a tungsten alloy busbar and a self-lubricating composite coating, wherein the self-lubricating composite coating consists of a pre-plating layer and a composite coating from the inside out. The tungsten alloy busbar is composed of metallic tungsten and rare earth elements, with metallic tungsten accounting for more than 80% and rare earth elements accounting for more than 0.1%. The proportion of metallic tungsten can be 85%, 90%, 95%, 97%, 99%, and all ranges and sub-ranges between these values; the proportion of rare earth elements can be 0.1%, 0.2%, 0.5%, 0.8%, 1.1%, 1.4%, and all ranges and sub-ranges between these values. Rare earth elements in the tungsten alloy wire can refine the tungsten grains, playing a dispersion strengthening role, thereby improving the tensile strength of the tungsten alloy wire itself. In addition, the rare earth elements in the tungsten alloy wire are one or more of the following elements: lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium.

[0007] The tungsten alloy wire has a diameter of 10-200µm and a tensile strength of over 3000MPa. Furthermore, the diameter of the tungsten alloy wire is 10µm, 15µm, 20µm, 25µm, 30µm, 35µm, 40µm, 45µm, 50µm, 55µm, 60µm, 65µm, 70µm, 75µm, 80µm, 85µm, 90µm, 95µm, 100µm, 105µm, 110µm, 115µm, 120µm, 125µm, 130µm, 135µm, 140µm, 145µm, 150µm, 155µm, 160µm, 165µm, 170µm, 175µm, 180µm, 185µm, 190µm, 195µm, 200µm, and all ranges and subranges between the above values. The tensile strength of the tungsten alloy wire is 3000MPa, 3050MPa, or 3100MPa, preferably 3200MPa, and most preferably 3300MPa.

[0008] The pre-plating layer is a chromium plating layer with a single-sided thickness of 0.1-1µm; the composite plating layer is a metal-based composite plating layer with a single-sided thickness of 0.1-5µm. Further, the single-sided thickness of the pre-plating layer is 0.1µm, 0.2µm, 0.3µm, 0.4µm, 0.5µm, 0.6µm, 0.7µm, 0.8µm, 0.9µm, 1µm, and all ranges and sub-ranges between these values; the composite plating layer is one or more of the following metal-based composite plating layers: copper-based composite plating, tin-based composite plating, lead-based composite plating, zinc-based composite plating, nickel-based composite plating, iron-based composite plating, cobalt-based composite plating, etc., preferably a copper-based composite plating layer. Copper has good thermal and electrical conductivity, as well as low hardness and good ductility, allowing it to deform simultaneously with the tungsten alloy wire during the drawing process. The composite coating has a single-sided thickness of 0.1µm, 0.5µm, 1µm, 1.5µm, 2µm, 2.5µm, 3µm, 3.5µm, 4µm, 4.5µm, 5µm, and all ranges and subranges between these values. Within this coating thickness range, the tungsten alloy wire can be completely covered by the electroplated layer, resulting in good drawing performance.

[0009] The composite coating contains a solid lubricant, and the content of the solid lubricant in the metal-based composite coating is 0.1-10 wt%. Further, the content of the solid lubricant in the metal-based composite coating is 0.1 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, 9 wt%, 9.5 wt%, 10 wt%, and all ranges and subranges between the above values.

[0010] The solid lubricant has a particle size of 2-10 µm. For example, the solid lubricant particle size can be 2 µm, 3 µm, 4 µm, 5 µm, 6 µm, 7 µm, 8 µm, 9 µm, 10 µm, and all ranges and subranges between these values. Within this particle size range, the solid particles can be uniformly dispersed in the plating solution.

[0011] The solid lubricant comprises 0-100 wt% metal compound, 0-100 wt% inorganic material, and 0-100 wt% organic material. The metal compound includes one or more of metal oxides, metal halides, metal sulfides, and metal selenides; the inorganic material is one or more of graphite, fluorinated graphite, and hexagonal boron nitride; and the organic material is one or more of polytetrafluoroethylene, polyimide, nylon, polyethylene, and melamine urate. In some preferred embodiments, the solid lubricating particles are molybdenum disulfide. Molybdenum disulfide has a graphite-like hexagonal layered structure, with each unit layer consisting of three stacked planar layers (S-Mo-S). Sulfur atoms are strongly covalently bonded to the corresponding molybdenum atoms, surrounding the molybdenum at the center like a triangular prism. The distance between unit layers is 0.625 nm, and the van der Waals forces between adjacent layers are weak, which significantly reduces the shear force during interlayer misalignment and sliding. Therefore, molybdenum disulfide exhibits excellent solid lubrication performance. In addition, molybdenum disulfide has good corrosion resistance and electrical conductivity, and its operating temperature in an atmospheric environment can reach 350°C. Therefore, it can exist stably in the electroplating solution and, under the action of electric field force, it can be deposited on the tungsten alloy wire in combination with metal ions in the plating solution.

[0012] Further, the metal oxide is one or more of lead oxide, copper oxide, zinc oxide, tin oxide, molybdenum oxide, etc.; the metal sulfide is one or more of molybdenum disulfide, tungsten disulfide, iron sulfide, chromium sulfide, etc.; the metal halide is one or more of calcium fluoride, barium fluoride, lanthanum fluoride, etc.; the metal selenide is niobium diselenide; the inorganic solid lubricant is one or more of graphite, fluorinated graphite, hexagonal boron nitride, etc.; the organic solid lubricant is one or more of polytetrafluoroethylene, polyimide, nylon, polyethylene, melamine urate, etc. Preferably, the solid lubricant is composed of 50-80 wt% metal compound, 1-30 wt% inorganic compound, and 1-30 wt% organic compound; more preferably, the solid lubricant is composed of 70-80 wt% metal compound, 5-20 wt% inorganic compound, and 5-20 wt% organic compound.

[0013] This invention also provides a method for preparing the aforementioned tungsten alloy wire, comprising the following steps:

[0014] Step 1: Pre-treatment of tungsten alloy busbars;

[0015] Step 2: Electroplating. The tungsten alloy busbar obtained in Step 1 is placed in an electroplating tank to pre-plat the bottom metal layer, and then a composite coating is electroplated in the electroplating tank. After electroplating, the tungsten alloy busbar is washed with water and soaked in soap, and then wound onto the I-beam reel.

[0016] Step 3: Drawing. The tungsten alloy wire obtained in Step 2 is installed at the wire feeding end of the water tank drawing machine. The tungsten alloy wire is drawn multiple times until it reaches the required wire diameter. Preferably, the exit die in the drawing machine is a natural diamond die, which can improve the surface quality of the tungsten wire and reduce its ellipticity.

[0017] The detailed steps of the preprocessing in step 1 are as follows:

[0018] Step A: The tungsten alloy busbar is placed in an ultrasonic electrolytic alkaline washing tank for cleaning, followed by three steps of water washing, acid washing, and water washing. The alkaline solution consists of one or more of sodium hydroxide, sodium carbonate, and trisodium phosphate, with a concentration of 50-150 g / L, a temperature of 50-80℃, a degreasing time of 1-5 seconds, and an ultrasonic frequency of 10-100 Hz. Tungsten alloy wire has good corrosion resistance and is insoluble in strong acids such as hydrochloric acid, sulfuric acid, and nitric acid at room temperature, but dissolves only in a mixture of hydrofluoric acid and concentrated nitric acid. After oxidation, the tungsten oxide formed on the surface of the tungsten alloy wire is easily soluble in the alkaline solution. Usually, after the tungsten alloy wire is drawn with graphite emulsion, graphite and organic solvents may still remain on the surface. Therefore, it is necessary to anodize the tungsten alloy busbar and then dissolve it in the alkaline solution to remove the residual oxide scale, graphite emulsion, and organic solvents from the surface of the tungsten alloy busbar. The water washing process is a two-stage process using a counter-current method. After electrolysis, the tungsten alloy busbar first enters a hot water washing tank, then a cold water washing tank, and finally an acid pickling and activation tank. Before entering the electroplating tank, it is cleaned again with deionized water. The activation mechanism in the pretreatment and electroplating processes of this invention is as follows: Hydrofluoric acid has strong corrosiveness. Through the strong chemical corrosion of hydrofluoric acid, the passivation film on the surface of the tungsten alloy busbar is removed, and the surface of the tungsten alloy busbar is roughened, resulting in voids between the tungsten alloy busbar grains, some of which are hook-shaped. Electroplating on such a surface allows the chromium layer to firmly self-lock onto the surface of the tungsten alloy busbar, thereby enhancing the bonding force between the chromium plating layer and the tungsten alloy busbar. Simultaneously, metallic chromium and tungsten have the same body-centered cubic structure and similar coefficients of thermal expansion; therefore, chromium is chosen as the pre-plating layer. Impact nickel is used for pre-plating when preparing the diamond wire saw. During the pre-plating process, hydrogen gas with strong reducing properties is released on the cathode wire, further activating the metal surface.

[0019] Step B: Two-stage water washing. The counter-current water washing method is used. After the tungsten alloy busbar is degreased, it first enters the hot water washing tank at a temperature of 50-70℃ for 1-5 seconds, and then passes through the cold water washing tank.

[0020] Step C: Activate the surface of the tungsten alloy busbar with concentrated hydrochloric acid or hydrofluoric acid at a temperature of 10-30℃ for 1-5 seconds, followed by activation and rinsing with water.

[0021] The process for pre-plating the underlying metal layer in step 2 is as follows: current density is 4-20 A / dm². 2 The electroplating time is 1-30 seconds; the anode is a lead-tin alloy or platinum-iridium anode; the electroplating solution consists of chromic anhydride: 100-400 g / L, sulfuric acid 1-5 g / L, and La. 3+ : 0.1-2.5g / L.

[0022] The electroplating process for the composite coating in step 2 is as follows: the electroplating solution consists of one or more of the following: 250 g / L metal oxides, metal halides, metal sulfides, and metal selenides; 100 g / L sulfuric acid; and 0.1-100 g / L solid lubricant; the current density is 8-10 A / dm³. 2 The concentration of the solid lubricant in the electroplating solution is 0.1-100 g / L. For example, the concentration of the solid lubricant is 0.1 g / L, 0.5 g / L, 0.8 g / L, 1 g / L, 5 g / L, 10 g / L, 20 g / L, 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, 100 g / L, and all ranges and sub-ranges between these values. Within this concentration range, the lubricated coating has a relatively high particle content and good lubricity.

[0023] This invention also provides a diamond wire saw made using the aforementioned tungsten alloy wire and its preparation method. The tungsten alloy wire is subjected to alkaline washing and acid washing pretreatment according to existing technology, followed by impact nickel plating, and then the diamond wire saw is prepared by composite electroplating. Preferably, the acid washing uses one or more of aminosulfonic acid, hydrochloric acid, or sulfuric acid. The impact nickel plating solution consists of nickel chloride: 200-300 g / L, hydrochloric acid: 100-200 ml / L, and a current density of 1-15 A / dm³. 2 The electroplating time is 5-15 seconds, and the electroplating solution temperature is 15-35℃.

[0024] The beneficial effects of this invention are as follows: On the one hand, by etching the tungsten alloy busbar with hydrofluoric acid and simultaneously adding a pre-plating underlayer, the bonding force between the electroplated layer and the tungsten alloy busbar is enhanced. At the same time, by adding solid lubricating particles to the electroplating solution to prepare a lubricating composite plating layer, the die wear during the drawing process is effectively reduced, saving costs. On the other hand, by changing the nickel sulfamate pre-plating process and using impact nickel as the pre-plating underlayer for the diamond wire, the bonding force between the grinding composite plating layer and the diamond wire busbar is improved, which can prevent problems such as wire breakage or silicon wafer scratches caused by the grinding composite plating layer peeling off during the diamond wire cutting process. Attached Figure Description

[0025] Figure 1 is a schematic cross-sectional view of the tungsten alloy wire of the present invention;

[0026] Figure 2 is a flowchart of the manufacturing process of the tungsten alloy wire of the present invention;

[0027] Figure 3 is a flowchart of the manufacturing process of the diamond wire saw of the present invention;

[0028] Figure 4 is a scanning electron microscope image of the product prepared in Example 1 of the present invention;

[0029] Figure 5 is a scanning electron microscope image of the product prepared according to Comparative Example 1 of the present invention;

[0030] Figure 6 is a scanning electron microscope image of the product prepared in Example 2 of the present invention.

[0031] Wherein: 1-tungsten alloy wire, 2-pre-plated metal layer, 3-self-lubricating composite coating. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] In some embodiments, the tungsten alloy wire comprises metallic tungsten and rare earth elements. The metallic tungsten accounts for more than 80%, and the rare earth elements account for more than 0.1%. For example, the proportion of metallic tungsten can be 85%, 90%, 95%, 97%, 99%, etc.; the proportion of rare earth elements can be 0.2%, 0.5%, 0.8%, 1.1%, 1.4%, etc. Rare earth elements in the tungsten alloy wire can refine the tungsten grains, playing a dispersion strengthening role, thereby improving the tensile strength of the tungsten alloy wire itself. Furthermore, the rare earth elements in the tungsten alloy wire are one or more of the following elements: lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium.

[0034] In some embodiments, the pre-plated metal layer is a chromium layer, pre-plated using an impact electroplating method, with a single-sided thickness of 0.1-1 μm. Chromium and tungsten have the same body-centered cubic structure and similar coefficients of thermal expansion. Using an impact electroplating method, hydrogen gas with strong reducing properties is released on the cathode wire, further activating the metal surface and enabling a strong bond between the chromium layer and the tungsten alloy substrate.

[0035] In some embodiments, the composite coating containing lubricating particles is one or more of the following composite coatings: copper-based composite coating, tin-based composite coating, lead-based composite coating, zinc-based composite coating, nickel-based composite coating, iron-based composite coating, and cobalt-based composite coating. In some preferred embodiments, the composite coating containing solid lubricating particles is a copper-based composite coating. Metallic copper has good thermal and electrical conductivity, as well as low hardness and good ductility, and can deform along with the wire during the tungsten alloy wire drawing process.

[0036] In some embodiments, the solid lubricant particles of the composite coating include metal compounds, inorganic substances, and organic substances. The metal compounds in the solid lubricant particles include one or more of metal oxides, metal halides, metal sulfides, and metal selenides. The metal oxides are one or more of lead oxide, copper oxide, zinc oxide, tin oxide, and molybdenum oxide; the metal sulfides are one or more of molybdenum disulfide, tungsten disulfide, iron sulfide, and chromium sulfide; the metal halides are one or more of calcium fluoride, barium fluoride, and lanthanum fluoride; the metal selenides are niobium diselenide; the inorganic solid lubricant is one or more of graphite, fluorinated graphite, and hexagonal boron nitride; and the organic solid lubricant is one or more of polytetrafluoroethylene, polyimide, nylon, polyethylene, and melamine urate. In some preferred embodiments, the solid lubricant particles are molybdenum disulfide. Molybdenum disulfide (MoD) possesses a graphite-like hexagonal layered structure. Each unit layer consists of three stacked planar layers: S-Mo-S. Sulfur atoms are strongly covalently bonded to their corresponding molybdenum atoms, surrounding the molybdenum at the center like a triangular prism. The distance between unit layers is 0.625 nm, and the van der Waals forces between adjacent layers are relatively weak. This significantly reduces the shear force during interlayer misalignment and sliding, thus giving MoD its excellent solid lubrication properties. Furthermore, MoD exhibits good corrosion resistance and electrical conductivity, and can operate at temperatures up to 350°C in atmospheric environments. Therefore, it can remain stable in electroplating solutions and, under the influence of an electric field, recombine with metal ions in the plating solution to deposit onto tungsten alloy wires.

[0037] In some embodiments, the thickness of the self-lubricating composite coating on one side is 0.5-5 μm. For example, the thickness of the self-lubricating composite coating on one side can be 0.8 μm, 1.6 μm, 3.2 μm, 4.8 μm, etc. Within this coating thickness range, the tungsten alloy busbar can be completely covered by the electroplated layer, resulting in good drawing performance.

[0038] In some embodiments, the solid lubricant particle size is between 2 and 10 μm. For example, the solid lubricant particle size can be 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, etc. Within this particle size range, the solid particles can be uniformly dispersed in the plating solution.

[0039] In some embodiments, the concentration of the solid lubricant in the electroplating solution is 0.1-100 g / L. For example, the concentration of the solid lubricant is 10 g / L, 20 g / L, 30 g / L, 40 g / L, 50 g / L, 60 g / L, etc. Within this concentration range, the lubricated coating has a relatively high particle content and good lubricity.

[0040] As shown in Figures 2 and 3, in some embodiments, a method for preparing a tungsten alloy wire and a diamond wire includes the following steps:

[0041] Step 1: Pre-treatment of the tungsten alloy busbar after electrolytic cleaning.

[0042] The pretreatment step in step one involves placing the tungsten alloy busbar into an ultrasonic electrolytic alkaline washing tank from the unloading end, followed by three steps of water washing, acid washing, and water washing before entering the electroplating tank. Tungsten alloy wire has good corrosion resistance; it is insoluble in strong acids such as hydrochloric acid, sulfuric acid, and nitric acid at room temperature, but dissolves only in a mixture of hydrofluoric acid and concentrated nitric acid. After oxidation, the tungsten oxide formed on the surface of the tungsten alloy wire is easily soluble in alkaline solutions. Typically, after graphite emulsion drawing, graphite and organic solvents may still remain on the surface of the tungsten alloy wire. Therefore, it is necessary to anodize the tungsten alloy busbar and then dissolve it in an alkaline solution to remove residual oxide scale, graphite emulsion, and organic solvents from the surface of the tungsten alloy busbar. The water washing is a two-stage process using a counter-current method. After electrolysis, the tungsten alloy busbar first enters a hot water washing tank, then a cold water washing tank, and finally enters an acid washing and activation tank. Before entering the electroplating tank, it is washed again with deionized water.

[0043] In some embodiments, the alkaline solution is composed of one or more of sodium hydroxide, sodium carbonate, and trisodium phosphate, the concentration of the alkaline solution is 50-150 g / L, the temperature is 50-80℃, the degreasing time is 1-5 s, and the ultrasonic frequency is 10-100 Hz; the water temperature in the water washing tank after electrolytic cleaning is 50-70℃, and the time is 1-5 s.

[0044] In some embodiments, concentrated hydrochloric acid or hydrofluoric acid is used to activate the surface of the tungsten alloy busbar, with the acid temperature at 10-30°C and the time at 1-5 seconds.

[0045] In some embodiments, the composition of the impact chromium plating solution is chromic anhydride: 100-400 g / L, sulfuric acid 1-5 g / L, La 3+ 0.1-2.5 g / L current density is 4-20 A / dm³ 2 The electroplating time is 1-30 seconds, and the anode is a lead-tin alloy or platinum-iridium anode.

[0046] Step 2: Electroplating self-lubricating composite coating. After activation and washing, the tungsten alloy busbar enters the electroplating tank for pre-plating of the bottom metal coating, and then enters the electroplating tank for electroplating of the lubricating composite coating. After electroplating, the wire undergoes water washing, drying, and soaping processes, and is then wound onto the I-beam reel by a servo motor at a certain spacing.

[0047] In some preferred embodiments, the lubricating composite coating is a copper-based composite coating, and the solid lubricant is molybdenum disulfide. The electroplating solution consists of 200-300 g / L copper sulfate and 100-200 g / L sulfuric acid, at a temperature of 10-30°C and a current density of 5-20 A / dm³. 2 Drying is carried out in a heating furnace at a temperature of 200-300℃ for 1-5 seconds. After soaping, a lubricating film is formed on the surface of the wire, which prevents oxidation of the steel wire surface and facilitates wire winding at the take-up end and subsequent drawing.

[0048] Step 3: Drawing. The electroplated tungsten alloy wire is installed at the wire feeding end of the water tank drawing machine. The alloy wire is drawn through multiple dies to achieve the required wire diameter.

[0049] In some embodiments, the export mold is made of natural diamond, which can improve the surface quality of the tungsten wire and reduce the ellipticity of the tungsten wire.

[0050] Specifically, to prepare the tungsten alloy wire products of this invention, a diamond wire saw is prepared by re-treating the drawn tungsten alloy wire with alkali washing, water washing, and acid washing. After impact nickel plating, a diamond wire saw is prepared by composite electroplating. The acid washing uses one or more of aminosulfonic acid, hydrochloric acid, or sulfuric acid. The impact nickel plating solution consists of nickel chloride: 200-300 g / L, hydrochloric acid: 100-200 ml / L, and a current density of 1-15 A / dm³. 2 The electroplating time is 5-15 seconds, the electroplating solution temperature is 15-35°C, and the coating thickness on one side is 0.1-1 μm. Example

[0051] This embodiment provides a method for preparing tungsten alloy wire and a finished product.

[0052] Step 1: The tungsten alloy busbar enters the ultrasonic electrolytic alkaline washing tank from the unloading end. The alkaline solution is sodium hydroxide with a concentration of 70 g / L, a temperature of 70℃, a washing time of 5 seconds, and an ultrasonic frequency of 25 Hz. After degreasing, the tungsten alloy busbar enters a two-stage hot and cold water washing tank, using a counter-current method to completely clean the alkaline solution from the surface of the tungsten wire. The hot water washing temperature is 60℃, and the cold water washing temperature is 25℃. After washing, the tungsten alloy busbar enters an acid pickling and activation tank, where hydrofluoric acid is used for etching and activation. The hydrofluoric acid concentration is 20%, the temperature is 25℃, and the activation time is 3 seconds.

[0053] Step Two: Electroplating is performed after pretreatment. First, metallic chromium is pre-plated onto the surface of the tungsten alloy busbar as a base bonding layer. The impact chromium anode is a lead-tin alloy, and the electroplating solution consists of chromic anhydride: 250 g / L, sulfuric acid: 2 g / L, and lanthanum nitrate: 5 g / L, with a current density of 15 A / dm³. 2 The electroplating time was 9 seconds, and the thickness of the plating layer on one side was 0.5 μm. After the pre-plating layer was completed, a copper layer was electroplated on the metallic chromium. The electroplating solution consisted of 250 g / L copper sulfate and 100 g / L sulfuric acid, with a current density of 10 A / dm³. 2 The coating thickness on one side is 2μm. After washing, drying, and soaping, the wire is wound onto the I-beam reel by a servo motor at a certain spacing.

[0054] Step 3: Drawing. The electroplated tungsten alloy wire is installed on the wire feeding end of the water tank drawing machine. After multiple drawing passes through the molds, the alloy wire reaches the required wire diameter, and the final product is obtained.

[0055] Comparative Example 1

[0056] Step 1: The tungsten alloy busbar enters the ultrasonic electrolytic alkaline washing tank from the unloading end. The alkaline solution is sodium hydroxide with a concentration of 70 g / L, a temperature of 70℃, a washing time of 5 seconds, and an ultrasonic frequency of 25 Hz. After degreasing, the tungsten alloy busbar enters a two-stage hot and cold water washing tank, using a counter-current method to completely clean the alkaline solution from the surface of the tungsten alloy busbar. The hot water washing temperature is 60℃, and the cold water washing temperature is 25℃. After water washing, the tungsten alloy busbar enters an acid pickling and activation tank, where hydrofluoric acid is used for etching and activation. The hydrofluoric acid concentration is 20%, the temperature is 25℃, and the activation time is 3 seconds.

[0057] Step Two: Electroplating is performed after pretreatment. A copper layer is electroplated onto the tungsten alloy busbar. The electroplating solution consists of 250 g / L copper sulfate and 100 g / L sulfuric acid, with a current density of 10 A / dm³. 2 The coating thickness on one side is 2µm. After washing, drying, and soaping, the wire is wound onto the I-beam reel by a servo motor at a certain spacing.

[0058] Step 3: Drawing. The electroplated tungsten alloy wire is installed at the unloading end of the water tank drawing machine. After multiple drawing passes through dies, the alloy wire reaches the required diameter, yielding the final product. Example

[0059] Step 1: The tungsten alloy busbar enters the ultrasonic electrolytic alkaline washing tank from the unloading end. The alkaline solution is sodium hydroxide with a concentration of 70 g / L, a temperature of 70℃, a washing time of 5 seconds, and an ultrasonic frequency of 25 Hz. After degreasing, the tungsten alloy busbar enters a two-stage hot and cold water washing tank, using a counter-current method to completely clean the alkaline solution from the surface of the tungsten alloy busbar. The hot water washing temperature is 60℃, and the cold water washing temperature is 25℃. After water washing, the tungsten alloy busbar enters an acid pickling and activation tank, where hydrofluoric acid is used for etching and activation. The hydrofluoric acid concentration is 20%, the temperature is 25℃, and the activation time is 3 seconds.

[0060] Step Two: After pretreatment, perform self-lubricating composite plating. First, pre-plat metallic chromium is applied to the surface of the tungsten alloy busbar as the underlying bonding layer. The impact chromium anode is a lead-tin alloy, and the plating solution consists of chromic anhydride: 250 g / L, sulfuric acid: 2 g / L, and lanthanum nitrate: 5 g / L, with a current density of 15 A / dm³. 2 The electroplating time was 9 seconds, and the thickness of the plating layer on one side was 0.5 μm. After the pre-plating layer was completed, a copper-based lubricating composite plating layer was electroplated on the metallic chromium. The electroplating solution consisted of 250 g / L copper sulfate and 100 g / L sulfuric acid, with a current density of 10 A / dm³. 2 The solid lubricating particles are molybdenum disulfide, with a particle concentration of 50 g / L, a particle size of 2 μm, and a single-sided coating thickness of 2 μm. After washing, drying, and soaping, the material is wound onto an I-beam reel by a servo motor at a certain spacing.

[0061] Step 3: Drawing. The electroplated tungsten alloy wire is installed on the wire feeding end of the water tank drawing machine. After multiple drawing passes through the molds, the alloy wire reaches the required wire diameter, and the final product is obtained.

[0062] Comparative Example 2.1

[0063] Step 1: The tungsten alloy busbar enters the ultrasonic electrolytic alkaline washing tank from the unloading end. The alkaline solution is sodium hydroxide with a concentration of 70 g / L, a temperature of 70℃, a washing time of 5 seconds, and an ultrasonic frequency of 25 Hz. After degreasing, the tungsten alloy busbar enters a two-stage hot and cold water washing tank, using a counter-current method to completely clean the alkaline solution from the surface of the tungsten alloy busbar. The hot water washing temperature is 60℃, and the cold water washing temperature is 25℃. After water washing, the tungsten alloy busbar enters an acid pickling and activation tank, where hydrofluoric acid is used for etching and activation. The hydrofluoric acid concentration is 20%, the temperature is 25℃, and the activation time is 3 seconds.

[0064] Step Two: Electroplating is performed after pretreatment. First, metallic chromium is pre-plated onto the surface of the tungsten alloy busbar as a base bonding layer. The impact chromium anode is a lead-tin alloy, and the electroplating solution consists of chromic anhydride: 250 g / L, sulfuric acid: 2 g / L, and lanthanum nitrate: 5 g / L, with a current density of 15 A / dm³. 2The electroplating time was 9 seconds, and the thickness of the plating layer on one side was 0.5 µm. After the pre-plating layer was completed, a copper layer was electroplated onto the metallic chromium. The electroplating solution consisted of 250 g / L copper sulfate and 100 g / L sulfuric acid, with a current density of 10 A / dm³. 2 The thickness of the coating on one side is 2µm.

[0065] Step 3: Drawing. The electroplated tungsten alloy wire is installed at the wire feeding end of the water tank drawing machine. The alloy wire is drawn through multiple dies to reach the required wire diameter.

[0066] Comparative Example 2.2

[0067] Step 1: The tungsten alloy busbar enters the ultrasonic electrolytic alkaline washing tank from the unloading end. The alkaline solution is sodium hydroxide with a concentration of 70 g / L, a temperature of 70℃, a washing time of 5 seconds, and an ultrasonic frequency of 25 Hz. After degreasing, the tungsten alloy busbar enters a two-stage hot and cold water washing tank, using a counter-current method to completely clean the alkaline solution from the surface of the tungsten alloy busbar. The hot water washing temperature is 60℃, and the cold water washing temperature is 25℃. After water washing, the tungsten alloy busbar enters an acid pickling and activation tank, where hydrofluoric acid is used for etching and activation. The hydrofluoric acid concentration is 20%, the temperature is 25℃, and the activation time is 3 seconds.

[0068] Step Two: Electroplating is performed after pretreatment. First, metallic chromium is pre-plated onto the surface of the tungsten alloy busbar as a base bonding layer. The impact chromium anode is a lead-tin alloy, and the electroplating solution consists of chromic anhydride: 250 g / L, sulfuric acid: 2 g / L, and lanthanum nitrate: 5 g / L, with a current density of 15 A / dm³. 2 The electroplating time was 9 seconds, and the thickness of the plating layer on one side was 0.5 µm. After the pre-plating layer was completed, a copper layer was electroplated onto the metallic chromium. The electroplating solution consisted of copper pyrophosphate: 300 g / L, potassium pyrophosphate: 100 g / L, and the current density was 8 A / dm³. 2 The thickness of the coating on one side is 2μm.

[0069] Step 3: Drawing. The electroplated tungsten alloy wire is installed at the wire feeding end of the water tank drawing machine. The alloy wire is drawn through multiple dies to reach the required wire diameter.

[0070] Figures 4 and 5 correspond to Example 1 and Comparative Example 1, respectively. As can be seen from Figures 4 and 5, in Example 1, after pre-plating with a chromium layer, the coating has good adhesion to the tungsten alloy wire substrate, and there is no coating peeling after knotting. In Comparative Example 1, without pre-plating with a chromium layer, the coating has poor adhesion to the tungsten alloy wire substrate, and there is obvious coating peeling after knotting.

[0071] The tungsten alloy wires prepared in Example 2 and Comparative Examples 2.1 and 2.2 were drawn, and the experimental results are shown in Table 1:

[0072] Table 1. Drawing test results of tungsten alloy wires prepared in Example 2 and Comparative Examples 2.1 and 2.2.

[0073] Mold Specifications (μm) 56524945423937353331 Example 2 Mold Usage Mileage 975983967988935946831835867889 Comparative Example 2.1 Mold Usage Mileage 986956946953943985346378397339 Comparative Example 2.2 Mold Usage Mileage 946953958912934948348365346359 surface

[0074] According to the test results in Table 1, the tungsten alloy wire with a single coating such as direct copper plating can only be drawn up to 400 km before the diameter of the last four dies gradually increases, rendering them unusable. However, with the tungsten alloy wire of this invention, which features a self-lubricating composite coating, the tungsten alloy wire can be drawn up to 800 km or more with the last four dies, effectively reducing die wear. The die usage mileage refers to the maximum length of metal wire that each die can draw while maintaining a constant die diameter.

[0075] Finally, it should be noted that the above descriptions are merely specific embodiments of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art. The general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing a tungsten alloy wire, characterized in that, The process includes the following steps: Step 1: Pre-treatment of the tungsten alloy busbar; Step 2: Electroplating, where the tungsten alloy busbar obtained in Step 1 is placed in an electroplating tank for pre-plating of the bottom metal layer, followed by electroplating of the composite layer in the electroplating tank. After electroplating, the tungsten alloy busbar undergoes water washing and soap immersion processes, and is then wound onto an I-beam reel. The process for pre-plating the bottom metal layer is as follows: current density of 4-20 A / dm³. 2 The electroplating time is 1-30 seconds; the anode is a lead-tin alloy or platinum-iridium anode; the electroplating solution consists of chromic anhydride: 100-400 g / L, sulfuric acid 1-5 g / L, and La. 3+ 0.1-2.5 g / L; The electroplating process for composite coatings is as follows: the electroplating solution consists of 250 g / L copper sulfate, 100 g / L sulfuric acid, and 0.1-100 g / L molybdenum disulfide solid lubricant; the current density is 8-10 A / dm³. 2 Step 3: Drawing. The tungsten alloy wire obtained in Step 2 is installed at the wire feeding end in the water tank drawing machine. The tungsten alloy wire is drawn multiple times to reach the required wire diameter. The detailed steps of the pretreatment in Step 1 are as follows: Step A: The tungsten alloy busbar is placed in an ultrasonic electrolytic alkaline washing tank for cleaning. The alkaline solution is one or more of sodium hydroxide, sodium carbonate, and trisodium phosphate. The concentration of the alkaline solution is 50-150 g / L, the temperature is 50-80℃, the degreasing time is 1-5 s, and the ultrasonic frequency is 10-100 Hz. Step B: Two-stage water washing. A countercurrent water washing method is used. After the tungsten alloy busbar is degreased, it first enters a hot water washing tank at a water temperature of 50-70℃ for 1-5 s, and then passes through a cold water washing tank. Step C: The surface of the tungsten alloy busbar is activated with hydrofluoric acid at a temperature of 10-30℃ for 1-5 s, followed by activation water washing.

2. A tungsten alloy wire, characterized in that, It is prepared by the method described in claim 1.

3. The tungsten alloy wire according to claim 2, characterized in that, It consists of a tungsten alloy busbar and a self-lubricating composite coating. The self-lubricating composite coating consists of a pre-plating layer and a composite coating from the inside out. The pre-plating layer is a metallic chromium plating layer with a single-sided thickness of 0.1-1µm. The composite coating is a metal-based composite coating with a single-sided thickness of 0.1-5µm. The metal-based composite coating contains a solid lubricant with a content of 0.1-10wt%. The solid lubricant is molybdenum disulfide.

4. The tungsten alloy wire according to claim 3, characterized in that, The tungsten alloy wire has a diameter of 10-200µm and a tensile strength of over 3000MPa.

5. A tungsten alloy wire product, characterized in that, It is processed from the tungsten alloy wire described in any one of claims 2-4.

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