Tungsten alloy wire and preparation method thereof

Abstract

The invention relates to the technical field of tungsten alloy materials, in particular to a tungsten alloy wire and a preparation method thereof. The tungsten alloy is prepared from the following elements in percentage by mass: 0.4 to 1.1 weight percent of L, 0 to 0.01 weight percent of X, 0.001 to 0.25 weight percent of Z and the balance of tungsten and inevitable impurities, wherein L is one or more than two of lanthanum, cerium, praseodymium, neodymium, gadolinium and erbium; x is one or more than two of yttrium, hafnium, zirconium, europium, ytterbium, dysprosium, holmium, terbium, lutetium, scandium, samarium, cobalt, ruthenium and rhenium; the Z comprises oxygen; the residual carbon element on the surface of the wire rod is less than 10 ppm. According to the method, the residual carbon element on the surface of the tungsten alloy wire is controlled to be below a certain value, the negative effect of the residual carbon element on the binding force of a subsequent electroplated metal layer on the surface of the tungsten alloy wire in the electroplating process can be reduced, and therefore the breaking force of the electroplated tungsten alloy wire after electroplating is remarkably improved.

Description

[0001] This application claims the priority of the Chinese patent application filed with the China Patent Office on December 26, 2023, with application number 2023118259397 and invention name “A tungsten alloy wire, its preparation method and application”, the entire contents of which are incorporated by reference in this application. Technical Field

[0002] The present application relates to the technical field of tungsten alloy materials, and in particular to a tungsten alloy wire and a preparation method thereof. Background Art

[0003] Tungsten-based alloy is an alloy material made of refractory metal tungsten as the hard phase and nickel, iron, copper or silver as the bonding phase through powder metallurgy or injection molding technology. Due to its excellent thermal, mechanical, electrical and chemical properties, it is widely used in automobiles, medical care, aerospace, military, defense and other fields.

[0004] During the preparation of tungsten alloy wires, after drawing, annealing and other processes, the tungsten alloy wires before cleaning will have residual graphite emulsion and tungsten oxide. At present, the conventional electrolytic cleaning process of tungsten alloy wires uses AC electrolysis to clean the graphite emulsion and tungsten oxide on the surface of the wires.

[0005] However, the treatment effect of the existing cleaning process is not good, and the surface grooves and fine cracks of the wire are not leveled significantly. The breaking force of the tungsten alloy wire obtained by electroplating after cleaning is low. Summary of the invention

[0006] In order to solve the problems of the prior art mentioned in the background technology, the present application provides a tungsten alloy wire, and its technical solution is as follows: The present application provides a tungsten alloy wire, wherein the tungsten alloy is composed of the following elements in mass fraction: L 0.4-1.1wt%, X 0-0.01wt%, Z 0.001-0.25wt%, and the balance is tungsten and unavoidable impurities; wherein L is one or more of lanthanum, cerium, praseodymium, neodymium, gadolinium, and erbium; wherein X is one or more of yttrium, hafnium, zirconium, europium, ytterbium, dysprosium, holmium, terbium, lutetium, scandium, samarium, cobalt, ruthenium, and rhenium; wherein Z includes oxygen; and the surface carbon element residue of the wire is less than 10ppm.

[0007] For example, L represents lanthanum, or cerium, or praseodymium, or lanthanum and cerium, or lanthanum and neodymium, or lanthanum and praseodymium, or lanthanum and gadolinium, or cerium and praseodymium, or cerium and neodymium, or praseodymium and gadolinium, or praseodymium and erbium, or neodymium and gadolinium, or lanthanum, cerium and praseodymium, or lanthanum, cerium and erbium, or lanthanum, praseodymium and neodymium, or cerium, praseodymium and neodymium, or praseodymium, neodymium, gadolinium and erbium, etc.; X represents yttrium and hafnium, or europium and ytterbium, or yttrium and lutetium, or yttrium and scandium, or yttrium and zirconium, or yttrium and rhenium, or europium and ruthenium, or yttrium, hafnium and zirconium, or yttrium, hafnium and europium, or yttrium, hafnium and ytterbium, or hafnium, zirconium and europium, or europium, ytterbium and dysprosium, or zirconium and rhenium, or yttrium, holmium, terbium and lutetium, etc.; For another example, the mass percentage of L is 0.4% to 1.1%, or 0.4% to 1.0%, or 0.4% to 0.8%, or 0.4% to 0.6%, or 0.4% to 0.5%, or 1.0 to 1.1%, or 0.8% to 1.1%, of course, it can also be 0.4%, 0.41%, 0.5%, 0.55%, 0.6%, 0.8%, 0.86%, 1.0%, 1.05%, etc.; The mass percentage of X is 0-0.01%, or 0-0.008%, or 0-0.005%, or 0-0.001%, or 0.001-0.01%, or 0.001-0.005%, of course, it can also be 0, 0.001%, 0.005%, 0.006%, 0.008%, 0.009%, 0.0099%, etc.; The mass percentage of Z is 0.001% to 0.25%, or 0.001% to 0.05%, or 0.001% to 0.1%, or 0.001% to 0.2%, or 0.005% to 0.1%, or 0.1% to 0.25%, or 0.1% to 0.2%, or 0.05% to 0.2%. Of course, it can also be 0.0009%, 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.05%, 0.1%, 0.15%, 0.2%, etc.

[0008] For another example, the residual carbon element on the surface of the wire is less than 10 ppm, or 9 ppm or less, or 8 ppm or less, or 6 ppm or less, or 5 ppm or less.

[0009] In some embodiments, the tungsten alloy is composed of the following elements in mass fraction: L 0.4-1.1wt%, Z 0.001-0.25wt%, and the remainder is tungsten and unavoidable impurities; wherein L is one or more of lanthanum, cerium, praseodymium, neodymium, gadolinium, and erbium; Z includes oxygen and boron; and the surface carbon element residue of the wire is less than or equal to 9ppm.

[0010] In some embodiments, the wire has a diameter of 20 to 60 μm, and in the wire, there is linear L or a compound of L along the wire axis, and the radial average width D of the L or the compound of L is ≤5 nm.

[0011] The wire diameter is 20-60 μm, for example, 20 μm, 28 μm, 30 μm, 38 μm, 40 μm, 48 μm, 50 μm, 55 μm, 58 μm, 60 μm, etc. The tungsten alloy wire can be uniform or incompletely uniform, and can also contain a difference of several percentages such as 1% according to the location; it should be noted that "linear" means that the size of L or L compound in the wire along the axial direction of the wire is much larger than the size along the radial direction of the wire.

[0012] The compound of L may be an oxide, such as lanthanum oxide, cerium oxide, praseodymium oxide, neodymium oxide, gadolinium oxide, erbium oxide, etc. Of course, it may also be a compound in other forms, such as carbide of L.

[0013] In some embodiments, in the wire, the radial average width of the tungsten grains is ≤80 nm; the number of L or the compound of L in the wire / the number of tungsten grains=γ, 3≤γ≤10.

[0014] Preferably, the number of surface defects on the wire is ≤10 / 100 meters.

[0015] Preferably, the dislocation density in the wire is ≥5*10 9 / mm 2 .

[0016] Preferably, when the wire diameter is greater than 50μm and ≤60μm, the radial average width D of L or L compound is ≤5nm, and the tensile strength of the wire is ≥5000MPa; when the wire diameter is greater than 40μm and ≤50μm, the radial average width D of L or L compound is ≤4nm, and the tensile strength of the wire is ≥5500MPa; when the wire diameter is greater than 30μm and ≤40μm, the radial average width D of L or L compound is ≤3nm, and the tensile strength of the wire is ≥6000MPa; when the wire diameter is greater than 20μm and ≤30μm, the radial average width D of L or L compound is ≤2nm, and the tensile strength of the wire is ≥7000MPa.

[0017] In some embodiments, Z further comprises one or more of carbon, boron, and nitrogen.

[0018] The present application also provides a method for preparing the above-mentioned tungsten alloy wire, which includes an electrolytic cleaning step; the process of the electrolytic cleaning step is: the tungsten alloy wire before cleaning is first electrolyzed by a potassium hydroxide solution with a concentration of 20wt% to 30wt% and containing 8 to 15 groups of AC electrolytic sheets, and then sequentially electrolyzed by 5 to 8 groups of potassium hydroxide solutions with a concentration of 5wt% to 10wt% and containing 5 to 10 groups of DC electrolytic sheets, and then the surface is cleaned with water to obtain the tungsten alloy wire; wherein the electrolysis speed is 50 to 200 m / min.

[0019] The surface layer of the black tungsten wire is first stripped by using high-concentration alkali solution and AC electrolysis, which can quickly remove the surface graphite layer and tungsten oxide layer, and effectively eliminate the surface grooves of the wire. The tungsten wire is then electropolished by low-concentration alkali solution and DC pulse mode. The resulting wire has better diameter uniformity and can effectively ensure that the wire diameter tolerance is within ±1% of the diameter.

[0020] The electrolytic cleaning method of the present application can be used to level the grooves and fine cracks on the surface of the wire, ensuring that the graphite material in the grooves and fine cracks can be well removed, thereby improving the surface cleanliness of the tungsten alloy wire and reducing the carbon residue on the surface of the tungsten alloy wire to below 10ppm. This can reduce the negative effect of the carbon residue during the electroplating process on the bonding force of the subsequent electroplated metal layer to the surface of the tungsten alloy wire, and significantly improve the breaking force of the electroplated tungsten alloy wire after electroplating.

[0021] In some embodiments, the preparation method of tungsten alloy wire comprises the steps of wet doping, powder making, pressing, sintering, blanking, pressure processing and electrolytic cleaning in sequence; wherein, the tungsten alloy wire before cleaning is obtained by wet doping, powder making, pressing, sintering, blanking and pressure processing in sequence, and then the tungsten alloy wire before cleaning is treated by the electrolytic cleaning step to obtain the tungsten alloy wire.

[0022] In some embodiments, the wet doping process is: blue tungsten powder is uniformly dispersed in deionized water to obtain a blue tungsten suspension, nano-scale compound powders of L and X (when X is 0%, nano-scale compound powder of X is not added in this step) are uniformly dispersed in an alkaline solution with a pH>11 to form a second suspension, and then a solution containing the Z element and the second suspension are sprayed into the blue tungsten suspension in sequence, and doped blue tungsten powder is obtained after heating and drying.

[0023] Preferably, the nano-scale compound powders of L and X are uniformly dispersed in an alkaline solution with a pH value greater than 11, and then stirred at a high speed of 1000 to 2000 r / min by a stirring device; Furthermore, the solution containing the Z element is a salt solution of the Z element or a suspension of a compound containing the Z element; It is preferred that the solution of element Z be diluted to a volume ratio of 1:20 or more; The preferred drying method is rapid vacuum heating drying.

[0024] By preparing a suspension of L and X element compounds, fine particles are directly and evenly doped into the blue tungsten powder, and the fine particles are used as heterogeneous crystal nuclei to co-crystallize and precipitate with tungsten particles. The tungsten alloy powder that can be prepared has a more uniform dispersion distribution. This method no longer requires the use of acid salts of elements, and the range of dispersed particles that can be prepared is wider, and the performance of the obtained tungsten material is more stable and reliable.

[0025] In some embodiments, the preparation method of the blue tungsten powder is: feeding ammonium paratungstate into a reduction furnace, reducing it at 400-600°C under hydrogen and nitrogen protection to obtain blue tungsten powder, wherein the thickness of the ammonium paratungstate powder layer is less than 10mm, the hydrogen flow rate in the reduction furnace is 20-40L / min, the nitrogen flow rate is 80-160L / min, the oxygen index of the blue tungsten powder is 2.85±0.05, and the ammonium tungsten bronze phase component is greater than 80%.

[0026] The production of blue tungsten powder uses hydrogen and nitrogen mixed gas as a reducing protective medium. The performance of the blue tungsten powder is controlled by the thickness of the material layer and the size and flow direction of the hydrogen. The oxygen index of blue tungsten is 2.85±0.05, and the blue tungsten with an ammonium tungsten bronze phase ratio of more than 80% is doped. The blue tungsten has coarse particles and many surface cracks, which is conducive to the entry of rare earth solution and improves the effectiveness of doping, thereby improving the uniformity of the second phase distribution in the tungsten wire and improving the comprehensive mechanical properties and processing performance of the tungsten wire.

[0027] In some embodiments, the powder making process is: reducing the doped blue tungsten powder to obtain alloy powder A with a particle size of 1.5 to 2.6 μm and alloy powder B with a particle size of 3.8 to 4.5 μm, respectively, and then mixing alloy powder A and alloy powder B to obtain a mixed powder; Preferably, the reduction method of the alloy powder A is: reducing the doped blue tungsten powder once in a 500-800° C. hydrogen reduction furnace, and then reducing it twice in a 700-1000° C. hydrogen reduction furnace to obtain alloy powder A with a particle size of 1.5-2.6 μm.

[0028] Preferably, the reduction method of the alloy powder B is: reducing the doped blue tungsten powder in a hydrogen reduction furnace at 700-1100° C. to obtain the alloy powder B with a particle size of 3.8-4.5 μm.

[0029] Preferably, the alloy powder A and the alloy powder B are mixed in a mass ratio of 1: (1-4). Further preferably, the alloy powder A and the alloy powder B are mixed in a mass ratio of 1: (1-2).

[0030] The fine-grained tungsten alloy powder prepared by double reduction is mixed with the coarse-grained tungsten alloy powder prepared by high-temperature single reduction in a certain proportion. This not only avoids the local uneven doping of the coarse-grained powder during the reduction process, but also effectively inhibits the agglomeration and enrichment of the fine-grained powder after reduction, making the subsequent alloy powder doping micro-uneven, resulting in defects in the subsequent pressure processing process and reducing the risk of wire breakage.

[0031] In some embodiments, the sintering process is: the pre-sintered blank obtained by pressing is sintered by electricity, and the sintering is carried out in two stages. The first sintering is carried out at 60% of the current intensity of the tungsten bar fusing current for 30 to 45 minutes and then cooled down. The second sintering is carried out at 90% to 92% of the current intensity of the tungsten bar fusing current for 40 to 80 minutes, and the density is 18.6 g / cm 3 The above sintered billets.

[0032] Preferably, the second sintering is carried out in a hydrogen atmosphere, wherein the purity of hydrogen is >99.5%.

[0033] The two-stage high-temperature sintering is different from the traditional one-time high-temperature sintering and the combined sintering mode of power sintering and medium-frequency indirect sintering. The density of the billet obtained by conventional one-time power sintering and vertical melting and medium-frequency combined sintering can only reach 17.2-18.4g / cm 3 , basically below 92% of the theoretical density, and the uniformity of the edge and core tissues is greatly different, that is, the tungsten wire fiber size consistency is poor, which leads to uneven processing tissues in the subsequent tungsten alloy material processing process, making the wire easy to break. The present invention fully volatilizes the impurity elements in the tungsten billet and closes the surface gaps of the tungsten billet through the first power-on sintering, improves the hydrogen purity and improves the billet density in the second power-on high-temperature sintering, obtains a uniform billet with a density of more than 96%, improves the billet tissue consistency, improves the subsequent tungsten alloy wire fiber consistency, and improves the winding performance of the tungsten alloy wire.

[0034] In some embodiments, the pressure processing process is: the alloy rod obtained by the blanking is recrystallized and annealed, and then forged into a tungsten rod with a diameter of 2.5 to 4.0 mm through a multi-pass continuous rotary forging device, and the tungsten rod is roughly drawn through drawing dies of different specifications, and the drawing passes are repeated for multiple times with a compression ratio of 35% to 60% to obtain a tungsten alloy thick wire with a diameter of 0.3 to 0.5 mm.

[0035] The tungsten alloy wire is processed with a large compression ratio of 35% to 60%, and the obtained wire fiber is more developed, which is conducive to the linearization of L element and its compounds during the processing, thereby improving the breaking force of the wire.

[0036] In some embodiments, the pressure processing process is: the alloy rod obtained by the blanking is heated to 2000-2600° C. by a medium / high frequency induction coil for recrystallization annealing.

[0037] In some embodiments, the tungsten alloy wire needs to be annealed when it is drawn to a diameter of 0.3-0.5 mm, and the annealing temperature is 1300-1800°C. After annealing, the tungsten alloy wire is cooled in an oxygen environment, and the annealing is repeated multiple times to obtain tungsten alloy wires of different diameters. When the tungsten alloy wire is drawn to less than 0.3 mm, no annealing is performed. The wire after annealing and cooling is drawn through wire drawing dies of different specifications, and the drawing is repeated multiple times to each wire to the required wire diameter.

[0038] By oxygen cooling the wire after annealing, the content and thickness of the oxide layer on the surface of the tungsten alloy wire can be increased, which can effectively improve the wire lubrication layer, thereby improving the drawing conditions and ensuring the feasibility of wire drawing with a large compression ratio, thereby greatly reducing the probability of wire breakage.

[0039] In addition, the preferred process of the pressing step is: isostatic pressing the mixed powder at a pressure of 140-240 MPa to form a green sheet with a single weight of 1.5-6 kg, and pre-sintering the green sheet at a low temperature of 1200-1400°C for 10-30 minutes in a hydrogen atmosphere to increase the strength of the green sheet; the preferred process of the green sheet opening step is: continuous rolling at 1600-1700°C using a multi-roll mill to open the sintered green sheet with a diameter of 15-25 mm into an alloy rod with a diameter of 8.0-12.0 mm.

[0040] The present application also provides an electroplated tungsten alloy wire, which includes the tungsten alloy wire as described above and an electroplated metal layer coated on the outer periphery of the tungsten alloy wire.

[0041] Compared with the prior art, the tungsten alloy wire provided in this application has the following advantages: The present application controls the surface carbon residue of the tungsten alloy wire to below a certain value, which can reduce the negative effect of the carbon residue during the electroplating process on the bonding force of the subsequent electroplated metal layer to the surface of the tungsten alloy wire, thereby significantly improving the breaking force of the electroplated tungsten alloy wire after electroplating. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0043] Figure 1 This is a transmission electron microscope image of the 28 μm tungsten alloy wire provided in Example 1.1 of the present application, with a scale of 100 nm; Figure 2 Another transmission electron microscope image of the 28 μm tungsten alloy wire provided in Example 1.1 of the present application; Figure 3 This is a schematic diagram of measuring the radial average width of L or a compound of L provided in the present application. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0045] The present application provides the following embodiments and comparative examples: The element compositions of the tungsten alloys of the embodiments and comparative examples are shown in Table 1 below: Table 1 (unit: wt%):

[0046] Among them, “-” means that the corresponding element is not added.

[0047] Example 1.1 This embodiment is a tungsten alloy wire prepared according to the present application, and its material element components include: 0.4wt% cerium, 0.4wt% praseodymium, 0.03wt% boron, 0.15wt% oxygen, and the remainder is tungsten and unavoidable impurities.

[0048] The preparation steps are as follows: Step 1, preparation of blue tungsten: the ammonium paratungstate powder is reduced by hydrogen in a reverse hydrogen continuous reduction furnace at 400°C, 450°C, 500°C and 560°C, the ammonium paratungstate powder layer thickness is 8mm, the hydrogen flow rate is 30L / min, the nitrogen flow rate is 140L / min, and blue tungsten powder is obtained, the oxygen index is 2.87, and the ammonium tungsten bronze phase component is 82%; Step 2, wet doping: the blue tungsten powder obtained in step 1 is uniformly dispersed in deionized water to obtain a blue tungsten suspension, wherein the volume ratio of the blue tungsten powder to the deionized water is 1:15; an appropriate amount of boric acid crystalline powder and deionized water are mixed at a volume ratio of 1:20 to obtain a boric acid solution, an appropriate amount of nano-powders of cerium oxide and praseodymium oxide are uniformly dispersed in a sodium hydroxide solution with a pH of 13, and stirred at a high speed of 1500r / min in a high-speed emulsifying device to form a second suspension, and then the boric acid solution and the second suspension are sprayed into the blue tungsten suspension through a vacuum pipe in turn, and after the spraying is completed, it is quickly vacuum heated and dried to obtain doped blue tungsten powder; Step 3, powder making: the doped blue tungsten powder obtained in step 2 is reduced once in a three-temperature zone hydrogen reduction furnace at 500°C, 650°C, and 750°C, and then reduced twice in a four-temperature zone hydrogen reduction furnace at 700°C, 810°C, 870°C, and 920°C to obtain alloy powder A with a particle size of 2.0 μm; The doped blue tungsten powder obtained in step 2 is reduced in a four-temperature zone hydrogen reduction furnace at 720° C., 820° C., 870° C., and 950° C. to obtain alloy powder B with a particle size of 4.1 μm; Alloy powder A and alloy powder B were placed in a high-energy powder mixer at a ratio of 1:1.5, and mixed for 120 minutes to obtain a mixed powder with a particle size of 3.0 μm. Step 4, pressing: the mixed powder obtained in step 3 is pressed into a green compact with a single weight of 3 kg at a pressure of 160 MPa by isostatic pressing, and the green compact is pre-sintered at 1300° C. in a hydrogen atmosphere for 20 minutes to obtain a pre-sintered green compact; Step 5, sintering: the pre-sintered blank obtained in step 4 is sintered by electricity. The sintering is carried out in two stages. The first sintering is carried out at a current intensity of 60% of the tungsten bar fusing current for 40 minutes, then the temperature is lowered, the vertical melting cover is purged and dried, and the second sintering is carried out at a current intensity of 91% of the tungsten bar fusing current for 60 minutes to obtain a density of 18.68g / cm 3 Sintered billet; Step 6, blanking: using a multi-roll rolling mill to continuously roll the sintered billet with a diameter of 20 mm into an alloy rod with a diameter of 8.0 mm at a heating temperature of 1600° C.; Step 7, pressure processing: the alloy rod obtained in step 6 is heated to 2400° C. by a high-frequency induction coil for recrystallization annealing, and then forged into a tungsten rod with a diameter of 3.0 mm by a multi-pass continuous rotary forging device; Step 8, the tungsten rod is roughly drawn through wire drawing dies of different specifications, and the drawing passes are repeated for multiple times with a compression ratio of 35% to 60% to obtain a tungsten alloy thick wire with a diameter of 0.5 mm; Step 9, annealing: the tungsten alloy wire obtained in step 8 is annealed when it is processed to φ0.5 mm, and the tungsten alloy wire is cooled in an oxygen environment after annealing, wherein the annealing temperature is 1600° C. when the diameter is 0.5 mm, and the mass percentage of oxide on the wire surface is 1.12%; Step 10, drawing the annealed wire obtained in step 9 through wire drawing dies of different specifications, and repeatedly drawing the wire to diameters of 58 μm, 48 μm, 38 μm, 28 μm, and 20 μm respectively; Step 11, electrolytic cleaning: The tungsten alloy wire obtained in step 10 is first electrolyzed by a 22wt% potassium hydroxide solution, which includes 12 sets of AC electrolytic sheets, and then sequentially electrolyzed by 6 sets of 6wt% potassium hydroxide solutions, which include 5 sets of DC electrolytic sheets. The electrolysis speed is 180m / min. After electrolysis, the surface is cleaned with deionized water to obtain white fine tungsten wires of different wire diameters.

[0049] Example 1.2 The material element composition is the same as that of Example 1.1. The difference between Example 1.2 and Example 1.1 is that in step 3, alloy powder A and alloy powder B are mixed at a ratio of 1:4 during powder preparation; the remaining preparation steps are the same as those of Example 1.1.

[0050] Example 1.3 The difference between this embodiment and embodiment 1.1 is that its material element composition includes 0.2wt% cerium, 0.2wt% praseodymium, 0.01wt% boron, 0.08wt% oxygen, and the balance is tungsten and unavoidable impurities; the remaining preparation steps are the same as embodiment 1.1.

[0051] Example 1.4 The difference between this embodiment and embodiment 1.1 is that its material element composition includes 0.55wt% cerium, 0.55wt% praseodymium, 0.03wt% boron, 0.22wt% oxygen, and the balance is tungsten and unavoidable impurities; the remaining preparation steps are the same as embodiment 1.1.

[0052] Comparative Example 1 (using one-time electrolytic cleaning) The material element composition is the same as that of Example 1.1. The difference between Comparative Example 1 and Example 1.1 is that: Step 11, electrolytic cleaning: electrolyze the tungsten alloy wire obtained in step 10 with a potassium hydroxide solution having a concentration of 22wt%, which includes 12 sets of AC electrolytic sheets, and wash the surface with deionized water after electrolysis to obtain white thin tungsten wires of different wire diameters. The remaining steps are the same as in Example 1.1.

[0053] Carbon residue on the wire surface and breaking force performance test after electroplating: The carbon residue on the wire surface and the increase in breaking force after electroplating of the tungsten alloy wires obtained in the examples and comparative examples were measured. The measurement results are shown in Table 2: The carbon residue on the surface of tungsten alloy wire is tested by carbon-sulfur analyzer. The balance method of carbon residue is as follows: using LECO CS844 carbon-sulfur analyzer, first weigh a certain amount of solvent and spread it on the bottom of the crucible, then put the tungsten alloy wire sample to be measured on the solvent, and then put the crucible with the sample and solvent on the furnace of carbon-sulfur analyzer and heat it until it melts. The carbon is completely converted into gas, and the carbon content is measured according to the calculated weight loss.

[0054] The measurement method of the breaking force increase of tungsten alloy wire electroplating is as follows: Tungsten alloy wires of different diameters were cleaned with sodium hydroxide solution in turn, and then electrolyzed with an electrolyte containing diamond particles to obtain a diamond wire saw with a nickel layer 10% thick on the surface of the tungsten alloy. The electrolyte composition was nickel sulfamate (450g / L) and boric acid (40g / L), the pH value of the electrolyte was 4.0, the temperature was 50°C, and the current density was 20A / m 2 The average particle size D50 of diamond particles is 4µm. The tensile force of tungsten alloy wire after electroplating is measured using a tensile testing machine. The electroplating tensile force increase = (tensile force after electroplating - tensile force before electroplating) / tensile force before electroplating.

[0055] Table 2

[0056] From the comparison results of Comparative Example 1 and Example 1.1, it can be seen that: In Comparative Example 1, conventional tungsten alloy wire electrolysis uses AC electrolysis to clean the graphite emulsion and tungsten oxide on the surface of the wire. It has no obvious effect on leveling the grooves and fine cracks on the wire surface. The residual carbon element on the wire surface is relatively high, both greater than 10ppm. The residual C element in the electroplating process has a strong negative effect on the subsequent bonding strength between the nickel layer and the tungsten wire surface, because the C element will combine with the nickel layer first, resulting in a low increase in the breaking force of the electroplated tungsten alloy wire.

[0057] The electrolytic cleaning method of the present application adopts AC electrolysis and high-concentration alkali solution to preferentially electrolytically refine the wire surface, and then adopts pulsed DC electrolysis and medium and low concentration alkali solution to level the grooves and fine cracks on the wire surface, ensuring that the graphite material in the grooves and fine cracks can be well removed, thereby improving the surface cleanliness of the tungsten alloy wire, which is reflected in the microstructure of the product to ultimately reduce the carbon element residue on the surface of the tungsten alloy wire to below 10ppm (specifically below 10ppm, or 9ppm and below, or 8ppm and below, or 6ppm and below, or 5ppm and below), thereby effectively reducing the negative effect of the residual carbon element in the electroplating process on the bonding force of the subsequent electroplated metal layer to the surface of the tungsten alloy wire, and significantly improving the breaking force of the electroplated tungsten alloy wire after electroplating.

[0058] Microstructure and other performance tests of tungsten alloy wire obtained in the embodiment The 28 μm tungsten alloy wire obtained in Example 1.1 was cut into thin slices along the axial direction of the tungsten alloy wire using a focused ion beam cutting device, and the thin slices were placed in a high-resolution transmission electron microscope and characterized using different modes to obtain Figure 1 and Figure 2 .

[0059] Figure 1In the graphite, the second phase elements cerium and praseodymium exist in linear form, and the number of linear second phases is 85, the number of tungsten grains is 11, and the number of linear second phases / the number of tungsten grains γ≈7.7.

[0060] Figure 2 In the figure, the red line indicates that the grain boundary angle of tungsten grains is greater than 15 degrees, and the white line indicates that the grain boundary angle of tungsten grains is less than 15 degrees. The proportion of tungsten grains with a grain boundary angle ≤15° = the number of tungsten grains with a grain boundary angle ≤15° / (the number of tungsten grains with a grain boundary angle ≤15° + the number of grain boundary angles>15°)*100%. The proportion of tungsten grains with a grain boundary angle ≤15° reached 94%.

[0061] The tungsten alloy wires obtained in the embodiment and the comparative example were subjected to a tensile strength test and characterized using a transmission electron microscope, and the γ value was calculated. The test results are shown in Table 3-4.

[0062] Among them, the tensile strength test method is: using a standard tensile machine, taking a 200mm long tungsten wire to clamp, loading at one end at a constant speed, and obtaining the breaking force data; The tensile strength is calculated by the following formula: σ=F / S, Where, F is the breaking force, N; S is the original cross-sectional area, mm; Table 3

[0063] The number of surface defects, the average diameter of tungsten grains, the radial average width of L or L compounds, and the dislocation density of the tungsten alloy wire obtained in the embodiment were measured. The measurement results are shown in Table 4.

[0064] The method for measuring the number of surface defects is as follows: the obtained tungsten alloy wire is tested for surface defects by an eddy current flaw detector, and the depth of the flaw detection signal exceeding 15% of the diameter is defined as a defect; The radial average width of tungsten grains is measured as follows: a thin slice is cut along the axial direction of the wire using a focused ion beam cutting device, the thin slice is placed in a scanning electron microscope with an EBSD (EBSD) to collect the morphology of the tungsten grains of the sample to be tested, and the width of the upper and lower grain boundaries is measured using conventional measurement software to obtain the radial width of the tungsten grains. The average value of the measured widths of multiple tungsten grains is the radial average width of the tungsten grains.

[0065] The radial mean width of a compound of L or L is measured as follows: Figure 3As shown, a focused ion beam cutting device is used to cut a thin slice along the axial direction of the tungsten alloy wire 1, and the thin slice is placed in a high-resolution transmission electron microscope. The morphology is first observed in the bright and dark field mode, and the position with obvious contrast in the morphology is selected for surface scanning, and a line scan is performed perpendicular to the axial position of the tungsten alloy wire to obtain the element distribution and element composition information. The position with obvious contrast and obvious difference in element distribution in the sample is photographed by a transmission electron microscope (that is, the position of the aggregation area of ​​each element of the second phase) to obtain a high-resolution image of the second phase, and the high-resolution image is Fourier transformed to obtain a lattice diffraction spectrum. The obtained second-phase diffraction spectrum is combined with the second-phase element composition information to calibrate the physical phase corresponding to each diffraction spectrum. By comparing the physical phase card, after confirming that the compound phase structure is L or L, the software measures the compound width of L or L; Figure 3 In the figure, 10 represents the tungsten matrix, 20 represents L or a compound of L, and the average value is calculated by measuring the widths of multiple Ls, that is, the radial average width of L or the compound of L. It can be understood that for the sake of convenience, Figure 3 What is captured is a partial cross section of the tungsten alloy wire sheet, not the entire sheet.

[0066] The test method for dislocation density is: use focused ion beam cutting equipment to cut a thin slice along the axial direction of the tungsten alloy wire, place the thin slice in a high-resolution transmission electron microscope to directly observe the lattice pattern, obtain the dislocation, and calculate the number of dislocation lines passing through the unit cross-sectional area to obtain the dislocation density.

[0067] Table 4

[0068] The average width of the tungsten grain size is characterized from another dimension as the proportion of the grain boundary angle of the tungsten grains ≤ 15°. The grain boundary angle proportion of the tungsten alloy wire obtained in the embodiment is measured, and the measurement results are shown in Table 5.

[0069] Among them, the measurement method of the grain boundary angle ratio is as follows: use a focused ion beam cutting device to cut a thin slice along the axial direction of the tungsten alloy wire, place the thin slice in a scanning electron microscope with an EBSD (EBSD) to collect the orientation difference information between the tungsten grains of the thin slice sample and the surrounding tungsten grains, and measure the ratio of grain boundaries with an angle difference of ≤15°.

[0070] Table 5

[0071] The number of surface defects and the average length of the tungsten alloy wire obtained in the embodiment were measured. The measurement results are shown in Table 6: Table 6

[0072] From the test results we can see that: The number of surface defects of the tungsten alloy wire provided in the embodiment of the present application is less than 10 / 100 meters; at 28 μm, L or L compounds exist in linear form, and their radial average width is less than 4 nm, the radial average width of tungsten grains is less than 80 nm, and the dislocation density in the wire is greater than 5*10 9 / mm 2 , the number of L or L compounds in the wire / the number of tungsten grains = γ, 3≤γ≤10. The present application greatly reduces the risk of crack breakage, and the mechanical strength and processing performance of the tungsten alloy wire are significantly improved, so that the wire can be refined to a wire diameter of 20 to 60 μm, and at 60 μm, it can have a tensile strength of more than 5000 MPa, and as the wire diameter decreases, its tensile strength increases accordingly, and at 28 μm, its tensile strength can reach more than 7000 MPa.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A tungsten alloy wire, characterized in that: The tungsten alloy is composed of the following elements in mass fraction: L 0.4-1.1wt%, X 0-0.01wt%, Z 0.001-0.25wt%, and the remainder is tungsten and unavoidable impurities; Wherein, L is one or more of lanthanum, cerium, praseodymium, neodymium, gadolinium, and erbium; X is one or more of yttrium, hafnium, zirconium, europium, ytterbium, dysprosium, holmium, terbium, lutetium, scandium, samarium, cobalt, ruthenium, and rhenium; Said Z comprises oxygen; The residual carbon element on the surface of the wire is less than 10 ppm.

2. The tungsten alloy wire according to claim 1, characterized in that: The tungsten alloy is composed of the following elements in mass fraction: L 0.4-1.1wt%, Z 0.001-0.25wt%, and the remainder is tungsten and inevitable impurities; the wire diameter of the wire is 20-60μm, and in the wire, there are linear L or L compounds along the wire axis, and the radial average width D of the L or L compounds is ≤5nm; Wherein, L is one or more of lanthanum, cerium, praseodymium, neodymium, gadolinium, and erbium; Said Z comprises oxygen and boron; The surface carbon residue of the wire is less than or equal to 9 ppm.

3. The tungsten alloy wire according to claim 1 or 2, characterized in that: In the wire, the radial average width of the tungsten grains is ≤80nm; The number of L or the compound of L in the wire / the number of tungsten grains=γ, 3≤γ≤10.

4. The tungsten alloy wire according to claim 1 or 2, characterized in that: When the wire diameter is greater than 50 μm and less than or equal to 60 μm, the radial average width D of L or the compound of L is less than or equal to 5 nm, and the tensile strength of the wire is greater than or equal to 5000 MPa; When the wire diameter is greater than 40 μm and less than or equal to 50 μm, the radial average width D of L or the compound of L is less than or equal to 4 nm, and the tensile strength of the wire is greater than or equal to 5500 MPa; When the wire diameter is greater than 30 μm and less than or equal to 40 μm, the radial average width D of L or the compound of L is less than or equal to 3 nm, and the tensile strength of the wire is greater than or equal to 6000 MPa; When the wire diameter is ≥20 μm and ≤30 μm, the radial average width D of L or the compound of L is ≤2 nm, and the tensile strength of the wire is ≥7000 MPa; The dislocation density in the wire is ≥5*10 9 / mm 2 ; The number of surface defects of the wire is ≤10 / 100 meters.

5. The tungsten alloy wire according to claim 1, characterized in that: The Z further comprises one or more of carbon, boron and nitrogen.

6. A method for preparing a tungsten alloy wire, characterized in that: including an electrolytic cleaning step; The process of the electrolytic cleaning step is: The tungsten alloy wire before cleaning is first electrolyzed by a potassium hydroxide solution with a concentration of 20wt% to 30wt% and containing 8 to 15 groups of AC electrolyte sheets, and then sequentially electrolyzed by 5 to 8 groups of potassium hydroxide solutions with a concentration of 5wt% to 10wt% and containing 5 to 10 groups of DC electrolyte sheets, and then the surface is washed with water to obtain the tungsten alloy wire; Wherein, the electrolysis speed is 50-200 m / min.

7. The method for preparing a tungsten alloy wire according to claim 6, characterized in that: The method comprises the steps of wet doping, powder making, pressing, sintering, blanking, pressure processing and electrolytic cleaning in sequence; The tungsten alloy wire before cleaning is obtained by sequentially undergoing wet doping, powder making, pressing, sintering, blanking and pressure processing, and then the tungsten alloy wire before cleaning is treated by the electrolytic cleaning step to obtain the tungsten alloy wire.

8. The method for preparing tungsten alloy wire according to claim 7, characterized in that: The wet doping process is as follows: blue tungsten powder is uniformly dispersed in deionized water to obtain a blue tungsten suspension, nanometer-scale compound powders of L and X are uniformly dispersed in an alkaline solution with a pH value greater than 11 to form a second suspension, and then a solution containing the Z element and the second suspension are sequentially sprayed into the blue tungsten suspension, and doped blue tungsten powder is obtained after heating and drying; The powder making process is: reducing the doped blue tungsten powder to obtain alloy powder A with a particle size of 1.5 to 2.6 μm and alloy powder B with a particle size of 3.8 to 4.5 μm, respectively, and then mixing the alloy powder A and the alloy powder B to obtain a mixed powder; The sintering process is as follows: the pre-sintered blank obtained by pressing is sintered by electricity, and the sintering is carried out in two stages. The first sintering is carried out at 60% of the current intensity of the tungsten bar fusing current for 30 to 45 minutes and then cooled down. The second sintering is carried out at 90% to 92% of the current intensity of the tungsten bar fusing current for 40 to 80 minutes to obtain a density of 18.6 g / cm 3 The above sintered billet; The pressure processing process is as follows: the alloy rod obtained by the blanking is recrystallized and annealed, and then forged into a tungsten rod with a diameter of 2.5-4.0 mm through a multi-pass continuous rotary forging device, and the tungsten rod is roughly drawn through wire drawing dies of different specifications, and the drawing passes are repeated for multiple times with a compression ratio of 35% to 60% to obtain a tungsten alloy thick wire with a diameter of 0.3-0.5 mm.

9. The method for preparing tungsten alloy wire according to claim 8, characterized in that: In the wet doping process, the preparation method of the blue tungsten powder is as follows: ammonium paratungstate is fed into a reduction furnace, and reduced at 400-600° C. under the protection of hydrogen and nitrogen to obtain blue tungsten powder, wherein the ammonium paratungstate powder layer thickness is less than 10 mm, the hydrogen flow rate in the reduction furnace is 20-40 L / min, the nitrogen flow rate is 80-160 L / min, the oxygen index of the blue tungsten powder is 2.85±0.05, and the ammonium tungsten bronze phase component is greater than 80%; In the powder making process, the reduction method of the alloy powder A is: the doped blue tungsten powder is reduced once in a hydrogen reduction furnace at 500-800° C., and then reduced twice in a hydrogen reduction furnace to obtain an alloy powder A with a particle size of 1.5-2.6 μm; the reduction method of the alloy powder B is: the doped blue tungsten powder is reduced in a hydrogen reduction furnace at 700-1100° C. to obtain an alloy powder B with a particle size of 3.8-4.5 μm; the alloy powder A and the alloy powder B are mixed in a mass ratio of 1: (1-2); During the pressure processing, the alloy rod obtained by the blanking is heated to 2000-2600°C by a medium / high frequency induction coil for recrystallization annealing; the tungsten alloy wire needs to be annealed when it is drawn to a diameter of 0.3-0.5 mm, and the annealing temperature is 1300-1800°C. After annealing, the tungsten alloy wire is cooled in an oxygen environment, and after annealing, it is repeatedly drawn multiple times to obtain tungsten alloy wires of different diameters.

10. An electroplated tungsten alloy wire, characterized in that: It comprises the tungsten alloy wire as described in any one of claims 1 to 5, and an electroplated metal layer coated on the outer periphery of the tungsten alloy wire.

Images