Tungsten alloy wire, and preparation method therefor and use thereof

Abstract

The present invention relates to the technical field of tungsten alloy materials, and in particular to a tungsten alloy wire, and a preparation method therefor and a use thereof. The tungsten alloy is composed of the following elements in percentage by mass: 0.45-0.9 wt% of L, 0.05-0.2 wt% of oxygen, and the balance being tungsten and inevitable impurities, wherein L is one or more of lanthanum, cerium, praseodymium, neodymium, gadolinium, and samarium, the wire has a wire diameter of 20-60 μm, in the wire, L or compounds of L exist in the axial direction of the wire in a linear shape, and the average width D of L or the compounds of L in the radial direction is less than or equal to 5 nm. The element L is controlled to be doped between the tungsten base materials in a linear shape, and the average width D of L in the radial direction to be less than or equal to 5 nm, so that cracks and wire breakage caused by second-phase particles in the subsequent pressure machining process are greatly reduced, thereby guaranteeing the mechanical strength of the tungsten alloy wire, and thus the wire has a tensile strength of 5000 MPa or above under a wire diameter of 20-60 μm, and the machining performance of the tungsten alloy wire is enhanced.

Description

A tungsten alloy wire and its preparation method and application Technical Field

[0001] The present invention relates to the technical field of tungsten alloy materials, and in particular to a tungsten alloy wire and a preparation method and application thereof. Background Art

[0002] Tungsten alloys are alloys composed of tungsten as a base and other elements. Among metals, tungsten has the highest melting point, exhibits excellent high-temperature strength and creep resistance, and exhibits excellent thermal and electrical conductivity and electron emission properties. Its high specific gravity makes it a popular choice for cemented carbide and alloying additives. Tungsten alloys are also widely used in aerospace, medical, automotive, and electronics industries.

[0003] To further improve the processing performance of tungsten alloys, tungsten materials are currently being dispersed and strengthened by doping the tungsten matrix with rare earth elements such as lanthanum, cerium, praseodymium, and neodymium. However, rare earth elements, as a second phase in the tungsten matrix, are susceptible to solid-liquid phase transitions during processing, such as high-temperature sintering and recrystallization annealing. These second-phase particles can coalesce and grow, causing numerous cracks at the interface between the second-phase particles and the tungsten wire. To prevent cracks from causing wire breakage during subsequent processing, the wire must be limited to a certain size, which is not conducive to the refinement of the tungsten alloy wire.

[0004] Summary of the Invention

[0005] In order to solve the problem in the prior art that the introduction of a second phase causes a large number of cracks and breakages in a tungsten alloy wire, the present invention provides a tungsten alloy wire, wherein the tungsten alloy is composed of the following elements by mass fraction: 0.45-0.9wt% L, 0.05-0.2wt% oxygen, and the balance being tungsten and unavoidable impurities;

[0006] Wherein, L is one or more of lanthanum, cerium, praseodymium, neodymium, gadolinium, and samarium;

[0007] For example, L is lanthanum, or cerium, or praseodymium, or neodymium, or lanthanum and cerium, or lanthanum and praseodymium, or lanthanum and gadolinium, or cerium and neodymium, or praseodymium and gadolinium, or neodymium and samarium, or lanthanum, cerium and praseodymium, or lanthanum, cerium and gadolinium, or cerium, praseodymium, neodymium and gadolinium, etc.;

[0008] For another example, the mass fraction of L is 0.45% to 0.9%, or 0.5% to 0.9%, or 0.7% to 0.9%, or 0.45% to 0.5%, or 0.45% to 0.8%, or 0.45%, 0.5%, 0.55%, 0.6%, 0.7%, 0.8%, 0.85%, etc.;

[0009] The mass fraction of oxygen is 0.05-0.2%, or 0.05-0.18%, or 0.1-0.2%, or 0.14%, 0.15%, 0.1%, 0.13%, 0.16%, 0.2, etc.

[0010] The wire diameter is 20-60 μm, such as 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 may be uniform or not completely uniform, and may also have a difference of several percentages such as 1% depending on the location;

[0011] In the wire, L or the compound of L exists in a linear form along the axial direction of the wire, and the average radial width D of the compound of L or L is ≤ 5 nm. It should be noted that "linear" means that the size of the compound of L or L in the axial direction of the wire is much larger than the size in 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, samarium oxide, etc. Of course, it may also be a compound in other forms.

[0013] Furthermore, the proportion of tungsten grain boundaries with an angle of ≤15° in the wire is ≥50%.

[0014] Furthermore, the average radial width of the tungsten grains in the wire is ≤80 nm.

[0015] Furthermore, when the wire diameter is greater than 50 μm and less than or equal to 60 μm, the average radial width D of the 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;

[0016] When the wire diameter is greater than 40 μm and less than or equal to 50 μm, the average radial width D of the L or L compound is less than or equal to 4 nm, and the wire tensile strength is greater than or equal to 5500 MPa;

[0017] When the wire diameter is greater than 30 μm and less than or equal to 40 μm, the average radial width D of the L or L compound is less than or equal to 3 nm, and the wire tensile strength is greater than or equal to 6000 MPa;

[0018] When the wire diameter is ≥20 μm and ≤30 μm, the average radial width D of L or the compound of L is ≤2 nm, and the tensile strength of the wire is ≥7000 MPa.

[0019] The present invention also provides a method for preparing the above-mentioned tungsten alloy wire, which includes wet doping, powdering, pressing, sintering, blanking, pressure processing and electrolytic cleaning.

[0020] Furthermore, the wet doping is as follows: blue tungsten powder is uniformly dispersed in deionized water to obtain a blue tungsten suspension, nano-scale compound powder of L is uniformly dispersed in an alkaline solution with a pH greater than 11 to form a second suspension, and the second suspension is sprayed into the blue tungsten suspension, and then heated and dried to obtain doped blue tungsten powder.

[0021] The nano-scale compound powder of L is preferably uniformly dispersed in an alkaline solution with a pH greater than 11, and then stirred at a high speed of 1000 to 2000 r / min by a stirring device;

[0022] The preferred drying method is rapid vacuum heating and drying.

[0023] By preparing a suspension of L 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 the element's acid salt form, and the range of dispersed particles that can be prepared is wider, resulting in more stable and reliable tungsten material performance.

[0024] Furthermore, the preparation method of the blue tungsten powder is: feeding ammonium paratungstate into a reduction furnace, and 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 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%.

[0025] Blue tungsten powder is produced using a hydrogen-nitrogen mixed gas as a reducing protective medium. The performance of the discharged blue tungsten powder is controlled by the thickness of the material layer and the size and flow direction of the hydrogen gas. The oxygen index of the 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 are conducive to the entry of rare earth solution, improve the doping effectiveness, and thus improve the uniformity of the second phase distribution in the tungsten wire, and improve the comprehensive mechanical properties and processing performance of the tungsten wire.

[0026] Furthermore, the powder making comprises: 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;

[0027] Preferably, the reduction method of the alloy powder A is: reducing the doped blue tungsten powder once in a hydrogen reduction furnace at 500-800°C, and then reducing it twice in a hydrogen reduction furnace at 700-1000°C to obtain alloy powder A with a particle size of 1.5-2.6 μm.

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

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

[0030] The fine-grained tungsten alloy powder prepared by two reductions is mixed in a certain proportion with the coarse-grained tungsten alloy powder prepared by one high-temperature reduction. 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, so that the subsequent alloy powder doping is microscopically uneven, resulting in defects in the subsequent pressure processing process and reducing the risk of wire breakage.

[0031] Furthermore, the sintering is specifically performed by sintering the pre-sintered billet obtained by pressing at a high temperature of 2200-2800°C.

[0032] Furthermore, the pressure processing 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 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.

[0033] The tungsten alloy wire is processed with a large compression ratio of 35% to 60%. 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.

[0034] Furthermore, during the press working, the alloy rod obtained by the blanking is heated to 2000-2600° C. by a medium / high frequency induction coil for recrystallization annealing.

[0035] Furthermore, the tungsten alloy wire is annealed at a temperature of 1300°C to 1700°C after being drawn to a diameter of 0.3 to 0.5 mm. After annealing, the tungsten alloy wire is cooled in an oxygen atmosphere. The cumulative processing deformation rate after annealing is ≥ 95%. After annealing, the wire is repeatedly drawn multiple times to obtain tungsten alloy wires of different diameters. When the tungsten alloy wire is drawn to less than 0.3 mm, no further annealing is performed.

[0036] 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.

[0037] The annealed wire is drawn through wire drawing dies of different specifications, and the drawing process is repeated multiple times to reach the required wire diameter.

[0038] Furthermore, the electrolytic cleaning is as follows: the prepared tungsten alloy wire is first subjected to high-concentration alkali solution and AC electrolysis, and then subjected to low-concentration alkali solution and DC electrolysis.

[0039] Preferably, the prepared tungsten alloy wire 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 washed with deionized water, wherein the electrolysis speed is 50 to 200 m / min.

[0040] The surface layer of the black tungsten wire is first stripped 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 using 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.

[0041] The present invention also provides an application of the above-mentioned tungsten alloy wire in the fields of cutting, cut-resistant protection, cables, screen printing, ropes or textiles.

[0042] Compared with the prior art, the tungsten alloy wire provided by the present invention has the following advantages:

[0043] The present invention uses one or more rare earth elements / rare earth compounds as the second phase to strengthen the tungsten material. By controlling the linear doping of L or L compounds between the tungsten matrix and ensuring that the average radial width of L or L compounds is ≤5nm, cracks and wire breaks caused by second phase particles during subsequent pressure processing are greatly reduced, which is beneficial to ensuring the mechanical strength of the tungsten alloy wire. The wire has a tensile strength of more than 5000MPa at a wire diameter of 20 to 60μm, and the processing performance of the tungsten alloy wire is enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction 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 invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0045] FIG1 is a schematic diagram of a method for measuring the average radial width of L or a compound of L provided by the present invention. DETAILED DESCRIPTION

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0047] The present invention provides a tungsten alloy wire, which is composed of the following elements by mass fraction: 0.45-0.9wt% L, 0.05-0.2wt% oxygen, and the balance being tungsten and unavoidable impurities;

[0048] Wherein, L is one or more of lanthanum, cerium, praseodymium, neodymium, gadolinium, and samarium;

[0049] It is understood that unavoidable impurities are other elements introduced during the preparation process.

[0050] The wire has a diameter of 20 to 60 μm. In the wire, L or the compound of L exists in a linear shape along the axial direction of the wire, and the average width D of L or the compound of L along the radial direction is ≤5 nm.

[0051] The proportion of tungsten grain boundaries with an angle of ≤15° in the wire is ≥50%;

[0052] The average radial width of the tungsten grains in the wire is ≤80nm;

[0053] When the wire diameter is greater than 50 μm and less than or equal to 60 μm, the average radial width D of the L or L compound is less than or equal to 5 nm, and the wire tensile strength is greater than or equal to 5000 MPa;

[0054] When the wire diameter is greater than 40 μm and less than or equal to 50 μm, the average radial width D of the L or L compound is less than or equal to 4 nm, and the wire tensile strength is greater than or equal to 5500 MPa;

[0055] When the wire diameter is greater than 30 μm and less than or equal to 40 μm, the average radial width D of the L or L compound is less than or equal to 3 nm, and the wire tensile strength is greater than or equal to 6000 MPa;

[0056] When the wire diameter is ≥20 μm and ≤30 μm, the average radial width D of L or the compound of L is ≤2 nm, and the tensile strength of the wire is ≥7000 MPa.

[0057] The present invention provides a preparation method of tungsten alloy wire, including wet doping, powder making, pressing, sintering, blanking, pressure processing, electrolytic cleaning, etc.

[0058] The wet doping method comprises the following steps: uniformly dispersing blue tungsten powder in deionized water to obtain a blue tungsten suspension; uniformly dispersing nano-scale compound powder of L in an alkaline solution with a pH value greater than 11 to form a second suspension; spraying the second suspension into the blue tungsten suspension; and rapidly vacuum heating and drying the mixture after spraying to obtain doped blue tungsten powder.

[0059] The preparation method of the blue tungsten powder comprises: feeding ammonium paratungstate into a reduction furnace, and reducing the ammonium paratungstate powder at 400-600° C. under the protection of hydrogen and nitrogen to obtain the blue tungsten powder, wherein the thickness of the ammonium paratungstate powder layer 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%;

[0060] The powder making process comprises: reducing the doped blue tungsten powder in a hydrogen reduction furnace at 500-800° C. for a primary reduction, and then reducing the doped blue tungsten powder in a hydrogen reduction furnace at 700-1000° C. for a secondary reduction to obtain alloy powder A with a particle size of 1.5-2.6 μm;

[0061] Reducing the doped blue tungsten powder in a hydrogen reduction furnace at 700-1100° C. to obtain alloy powder B with a particle size of 3.8-4.5 μm;

[0062] Alloy powder A and alloy powder B are mixed in a mass ratio of 1:(1-2) to obtain a mixed powder;

[0063] The sintering step is to sinter the pre-sintered billet obtained by pressing at a high temperature of 2200-2800°C to obtain a density of 18.6 g / cm 3 The above sintered billets;

[0064] Preferably, the sintering is carried out in a hydrogen atmosphere, wherein the hydrogen purity is >99.5%;

[0065] The press working comprises: heating the alloy rod obtained by the blanking to 2000-2600° C. by a medium / high frequency induction coil for recrystallization annealing, and then forging the alloy rod into a tungsten rod with a diameter of 2.5-4.0 mm by a multi-pass continuous rotary forging device;

[0066] The tungsten rod is roughly drawn through drawing dies of different specifications, and the drawing process is repeated 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;

[0067] The tungsten alloy wire needs to be annealed when drawn to a diameter of 0.3-0.5 mm, and the annealing temperature is 1300-1700° C. After annealing, the tungsten alloy wire is cooled in an oxygen environment, and the cumulative processing deformation rate after annealing is ≥95%.

[0068] The annealed wire is drawn through wire drawing dies of different specifications, and the drawing process is repeated multiple times to reach the required wire diameter.

[0069] In addition, the pressing and blanking steps in the above steps are preferably, but not limited to, implemented in the following manner:

[0070] Pressing: The mixed powder is pressed into a green compact with a single weight of 1.5 to 6 kg at a pressure of 140 to 240 MPa by isostatic pressing. The green compact is then pre-sintered at 1200 to 1400°C for 10 to 30 minutes in a hydrogen atmosphere to increase the green compact strength.

[0071] Coiling: The sintered billets with a diameter of 15 to 25 mm are continuously rolled at 1600 to 1700° C. using a multi-roll rolling mill to cobble into alloy rods with a diameter of 8.0 to 12.0 mm.

[0072] The preparation method also includes electrolytic cleaning: the prepared tungsten alloy wire 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 deionized water, wherein the electrolysis speed is 50 to 200 m / min.

[0073] To this end, the present invention provides the elemental compositions of tungsten alloys according to the following embodiments and comparative examples, as shown in Table 1:

[0074] Table 1 (unit: wt%):

[0075] Here, “-” indicates that the corresponding element is not added.

[0076] Example 1.1

[0077] This embodiment is a tungsten alloy wire prepared according to the present invention. The material element composition includes, by mass fraction, 0.6 wt% cerium, 0.137 wt% oxygen, and the balance tungsten and unavoidable impurities.

[0078] The preparation steps are as follows:

[0079] Step 1, preparation of blue tungsten: ammonium paratungstate powder is reduced with hydrogen in a reverse hydrogen continuous reduction furnace at 400°C, 450°C, 500°C, and 560°C. The thickness of the ammonium paratungstate powder layer is 8mm, the hydrogen flow rate is 30L / min, and the nitrogen flow rate is 140L / min. Blue tungsten powder is obtained, and its oxygen index is 2.87, and the ammonium tungsten bronze phase composition is 82%;

[0080] 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 cerium oxide nanopowder is uniformly dispersed in a sodium hydroxide solution with a pH of 13, and stirred at a high speed of 1500 r / min in a high-speed emulsification device to form a second suspension, and then the second suspension is sprayed into the blue tungsten suspension through a vacuum pipe. After the spraying is completed, it is quickly vacuum heated and dried to obtain the doped blue tungsten powder;

[0081] Step 3, powder preparation: The doped blue tungsten powder obtained in step 2 is reduced in a three-temperature zone hydrogen reduction furnace at 500°C, 650°C, and 750°C, and then reduced 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;

[0082] The doped blue tungsten powder obtained in step 2 was 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;

[0083] Alloy powder A and alloy powder B were placed in a high-energy powder mixer at a mass ratio of 1:1.5, and mixed for 120 minutes to obtain a mixed powder with a particle size of 3.0 μm.

[0084] Step 4, pressing: isostatically pressing the mixed powder obtained in step 3 at a pressure of 160 MPa to form a green compact weighing 3 kg, and pre-sintering the green compact at 1300° C. in a hydrogen atmosphere for 20 minutes to obtain a pre-sintered green compact bar;

[0085] Step 5: Sintering: The pre-sintered billet obtained in step 4 is sintered at 2600°C to obtain a density of 18.68 g / cm 3 Sintered billets;

[0086] Step 6, blanking: using a multi-roll rolling mill to continuously roll the 20 mm diameter sintered billet into an 8.0 mm alloy rod at a heating temperature of 1600°C;

[0087] Step 7, press working: 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;

[0088] Step 8: Roughly draw the tungsten rod through drawing dies of different specifications, repeat the drawing process multiple times with a compression ratio of 35% to 60%, and obtain a tungsten alloy thick wire with a diameter of 0.4 mm;

[0089] Step 9, annealing: the tungsten alloy thick wire obtained in step 8 is annealed, and after annealing, the tungsten alloy wire is cooled in an oxygen environment, wherein the annealing temperature is 1650° C., and the mass percentage of oxide on the wire surface is 1.18%;

[0090] Step 10: Drawing the annealed wire obtained in step 9 through wire drawing dies of different specifications, repeatedly drawing the wires to diameters of 60 μm, 48 μm, 38 μm, 28 μm, and 20 μm, respectively;

[0091] Step 11, electrolytic cleaning: The tungsten alloy wire obtained in step 10 is first electrolyzed in a 22wt% potassium hydroxide solution, which includes 12 sets of AC electrolytic sheets, and then sequentially electrolyzed in 6 sets of 6wt% potassium hydroxide solution, which includes 5 sets of DC electrolytic sheets. The electrolysis speed is 180m / min. After electrolysis, the surface is cleaned with deionized water to obtain white thin tungsten wires of different wire diameters.

[0092] Example 1.2

[0093] This embodiment is a tungsten alloy wire prepared according to the present invention. The material element composition includes, by mass fraction, 0.45 wt% lanthanum, 0.078 wt% oxygen, and the balance tungsten and unavoidable impurities.

[0094] The preparation steps are the same as those in Example 1.1 except that cerium oxide is replaced by lanthanum oxide in step 2.

[0095] Example 1.3

[0096] This embodiment is a tungsten alloy wire prepared according to the present invention. The material element composition includes, by mass fraction, 0.75wt% neodymium, 0.125wt% oxygen, and the balance tungsten and unavoidable impurities.

[0097] The preparation steps are the same as those in Example 1.1, except that cerium oxide is replaced by neodymium oxide in step 2.

[0098] Example 1.4

[0099] This embodiment is a tungsten alloy wire prepared according to the present invention. The material element composition includes, by mass fraction, 0.35wt% lanthanum, 0.4wt% praseodymium, 0.13wt% oxygen, and the balance tungsten and unavoidable impurities.

[0100] The preparation steps are the same as those in Example 1.1, except that cerium oxide is replaced by lanthanum oxide and praseodymium oxide in step 2.

[0101] Example 1.5

[0102] This embodiment prepares a tungsten alloy wire according to the present invention. The material element composition includes, by mass fraction, 0.35 wt% gadolinium, 0.4 wt% praseodymium, 0.115 wt% oxygen, and the balance being tungsten and unavoidable impurities.

[0103] The preparation steps are the same as those in Example 1.1, except that cerium oxide is replaced by gadolinium oxide and praseodymium oxide in step 2.

[0104] Example 1.6

[0105] This embodiment is a tungsten alloy wire prepared according to the present invention. The material element composition, calculated by mass fraction, includes: 0.35wt% samarium, 0.4wt% gadolinium, 0.172wt% oxygen, and the balance is tungsten and unavoidable impurities.

[0106] The preparation steps are the same as those in Example 1.1, except that cerium oxide is replaced by samarium oxide and gadolinium oxide in step 2.

[0107] Example 1.7

[0108] This example prepares a tungsten alloy wire according to the present invention. The elemental composition of the material is the same as in Example 1.1. The preparation steps differ from those in Example 1.1 in that, in step 3, alloy powder A and alloy powder B are mixed in a ratio of 1:4. The remaining preparation steps are the same as in Example 1.1.

[0109] Comparative Example 2.1

[0110] This embodiment is a tungsten alloy wire prepared according to the present invention. The material element composition includes, by mass fraction, 0.92wt% of cerium, 0.21wt% of oxygen, and the balance being tungsten and unavoidable impurities.

[0111] The preparation steps are the same as in Example 1.1.

[0112] Comparative Example 2.2

[0113] This embodiment is a tungsten alloy wire prepared according to the present invention. The material element composition includes, by mass fraction, 0.4wt% cerium, 0.52wt% lanthanum, 0.181wt% oxygen, and the balance being tungsten and unavoidable impurities.

[0114] The preparation steps are the same as those in Example 1.1, except that the second suspension in step 2 further includes lanthanum oxide.

[0115] Comparative Example 2.3

[0116] This embodiment is a tungsten alloy wire prepared according to the present invention. The material element composition includes, by mass fraction, 0.43wt% cerium, 0.098wt% oxygen, and the balance being tungsten and unavoidable impurities.

[0117] The preparation steps are the same as in Example 1.1.

[0118] Comparative Example 2.4

[0119] This embodiment prepares a tungsten alloy wire according to the present invention. The elemental composition of the material is the same as that of Example 1.1. The preparation steps differ from those of Example 1.1 in that: Step 8: Rough drawing a tungsten rod through drawing dies of different specifications, repeating the drawing passes multiple times with a compression ratio of 35% to 60%, to obtain a tungsten alloy coarse wire with a diameter of 0.2 mm; Step 9: Annealing: The coarse tungsten alloy wire obtained in Step 8 is annealed, and after annealing, the tungsten alloy wire is cooled in an oxygen environment, wherein the annealing temperature is 1650° C., and the mass percentage of oxide on the wire surface is 1.35%;

[0120] The remaining steps are the same as in Example 1.1.

[0121] Comparative Example 2.5

[0122] This embodiment prepares a tungsten alloy wire according to the present invention. The material element composition is the same as that of Example 1.1. The preparation steps differ from those of Example 1.1 in that: Step 8: The tungsten rod is drawn through drawing dies of different specifications, and the drawing passes are repeated multiple times with a compression ratio of 10% to 30% to obtain a tungsten alloy thick wire with a diameter of 0.4 mm.

[0123] The remaining steps are the same as in Example 1.1.

[0124] Comparative Example 2.6

[0125] This embodiment prepares a tungsten alloy wire according to the present invention. The material element composition is the same as that of Example 1.1. The preparation steps differ from those of Example 1.1 in that: Step 2, wet doping, comprises: uniformly dispersing the blue tungsten powder obtained in Step 1 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; dissolving an appropriate amount of nano-scale cerium oxide powder in deionized water, adding the solution to the blue tungsten suspension, and thoroughly stirring and drying the solution to obtain doped blue tungsten; the stirring speed is 40 r / min, and the drying temperature is 160°C.

[0126] The remaining steps are the same as in Example 1.1.

[0127] Performance Testing

[0128] The wires obtained in Examples 1.1-1.7 and Comparative Examples 2.1-2.3 were subjected to tensile strength tests, and the average diameter of the tungsten grains and the average radial width of the L or L compound were measured. The test results are shown in Table 2. The tensile strength test method is as follows: a standard tensile testing machine is used to clamp a 200 mm long tungsten wire, one end of which is loaded at a constant speed to obtain the breaking force data;

[0129] The tensile strength is calculated by the following formula: σ=F / S,

[0130] Where, F is the breaking force, N; S is the original cross-sectional area, mm;

[0131] The method for measuring the average radial width of tungsten grains is 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 multiple tungsten grain diameters is the average radial width of the tungsten grains.

[0132] [Corrected on 22.08.2024 according to Rule 91] The method for measuring the average radial width of L or its compound is as follows: as shown in FIG1 , a thin slice is cut out along the axial direction of the tungsten alloy wire 1 using a focused ion beam cutting device, and the thin slice is placed in a high-resolution transmission electron microscope. The morphology is first observed in bright and dark field modes, and a position with obvious morphological contrast 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 positions in the sample with obvious morphological contrast and obvious element distribution (i.e., the positions where the elements of the second phase are concentrated) are photographed by a transmission electron microscope 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, combined with the second-phase elemental composition information, is used to calibrate the phase corresponding to each diffraction spectrum. By comparing the phase cards, the structure of the L or L compound phase is confirmed. The software then measures the width of the L or L compound. In Figure 1, 10 represents the tungsten matrix, and 20 represents L or L compound. The average value of the widths of multiple L measurements is calculated, which is the radial average width of the L or L compound. It should be understood that for ease of explanation, Figure 1 captures a partial cross-section of the tungsten alloy wire sheet, not the entire sheet.

[0133] Table 2

[0134] Among them, “ / ” means there is no corresponding data.

[0135] As can be seen from Table 2, the tungsten alloy wire provided by the embodiment of the present invention has a tensile strength of more than 5000 MPa at a wire diameter of 20 to 60 μm, and its tensile strength increases with the reduction of the wire diameter. At 28 μm, its tensile strength can reach more than 7000 MPa. In addition, L or L compounds in the tungsten alloy wire provided by the embodiment of the present invention exist in a linear form, and their average radial width is less than 5 nm, and the average radial width of the tungsten grains is less than 80 nm.

[0136] From the comparison results of Comparative Examples 2.1-2.3 and Example 1.1, it can be seen that when the L content in the tungsten alloy wire is greater than 0.9wt%, the amount of the second phase in the tungsten alloy wire is too much, resulting in insufficient bonding between the grains of the tungsten alloy wire. At the same time, the increase in the amount of the second phase will greatly increase the difficulty of dislocation slip, resulting in increased difficulty in processing the tungsten alloy wire and inability to process it to below 60μm; when the L content in the tungsten alloy wire is less than 0.45wt%, the strengthening effect of the second phase on the tungsten alloy wire is not obvious, thereby reducing the tensile strength.

[0137] From the comparison results of Comparative Example 2.6 and Example 1.1, it can be seen that the average radial width of the tungsten grains of the wire obtained by the doping method of this patent is smaller, and the size of the second phase particles is also more slender. This is because this patent uses dispersed nano-scale powder particles to enter the tungsten powder through the early doping process, and its dispersion uniformity is better. At the same time, after the particles are reduced, there are more second-phase particles inside the tungsten grains, which has a better effect of refining the tungsten grains. At the same time, the small second-phase particles can better hinder the deformation of the tungsten grains, thereby improving the overall tensile strength of the tungsten wire.

[0138] The wires obtained in Example 1.1 and Comparative Examples 2.4 and 2.5 were subjected to a tensile strength test, and the grain boundary angle ratio was measured. The cumulative processing deformation rate of the wires was calculated. The test results are shown in Table 3.

[0139] Among them, the method for measuring the grain boundary angle ratio is as follows: use a focused ion beam cutting device to cut a thin slice along the tungsten alloy wire axially, place the thin slice in a scanning electron microscope with an EBSD (EBSD) instrument, collect the orientation difference information between the tungsten grains of the thin slice sample to be tested and the surrounding tungsten grains, and measure the ratio of grain boundaries with an angle difference of ≤15°.

[0140] The formula for the cumulative deformation rate of wire processing is: 1-D1*D1 / (D2*D2);

[0141] Where D1 is the wire diameter of the finished wire, and D2 is the wire diameter during annealing.

[0142] Table 3

[0143] Among them, “ / ” means there is no corresponding data.

[0144] From the comparison results of Comparative Example 2.4 and Example 1.1, it can be seen that when the tungsten alloy wire is annealed when the wire diameter is less than 0.3 mm, the proportion of tungsten grain boundary angles ≤ 15° in the obtained product is relatively small, resulting in more cracks and wire breaks caused by second-phase particles during subsequent pressure processing, which in turn affects the tensile strength.

[0145] Comparing the results of Comparative Example 2.5 with Example 1.1, it can be seen that when a conventional drawing pass compression ratio of 10% to 30% is used in the press working step, the average L width of the resulting wires of various specifications is larger, and the proportion of tungsten grain boundary angles ≤15° is smaller. This results in more cracks and wire breakage caused by second-phase particles during the subsequent press working process, which in turn affects the tensile strength and prevents processing below 40 microns. This indicates that using a high compression ratio of 35% to 60% for tungsten alloy wire processing results in more developed wire fibers, which is conducive to the fiberization of the L element and its compounds during processing, and the deformation of the tungsten grain boundaries is more rapid, thereby improving the tensile strength of the wire. At the same time, by setting the annealing point, the cumulative deformation after high-temperature annealing and the deformation degree of the wire are increased, thereby increasing the proportion of tungsten grain boundaries with small angles, further improving the tensile strength of the tungsten wire.

[0146] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above 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 invention.

Claims

1. A tungsten alloy wire, characterized in that: By mass fraction, the tungsten alloy is composed of the following elements: 0.45 - 0.9 wt% L, 0.05 - 0.2 wt% oxygen, and the balance is tungsten and inevitable impurities; wherein, the L is one or more of lanthanum, cerium, praseodymium, neodymium, gadolinium, and samarium; The wire diameter of the wire is 20 - 60 μm. In the wire, L or the compound of L exists linearly along the axial direction of the wire, and the average width D of L or the compound of L in the radial direction is ≤ 5 nm.

2. The tungsten alloy wire according to claim 1, wherein: The proportion of the grain boundary angle of tungsten grains in the wire ≤ 15° ≥ 50%; Preferably, the average width of tungsten grains in the wire in the radial direction is ≤ 80 nm; Preferably, when the wire diameter of the wire is > 50 μm and ≤ 60 μm, the average width D of L or the compound of L in the radial direction is ≤ 5 nm, and the tensile strength of the wire ≥ 5000 MPa; When the wire diameter of the wire is > 40 μm and ≤ 50 μm, the average width D of L or the compound of L in the radial direction is ≤ 4 nm, and the tensile strength of the wire ≥ 5500 MPa; When the wire diameter of the wire is > 30 μm and ≤ 40 μm, the average width D of L or the compound of L in the radial direction is ≤ 3 nm, and the tensile strength of the wire ≥ 6000 MPa; When the wire diameter of the wire is ≥ 20 μm and ≤ 30 μm, the average width D of L or the compound of L in the radial direction is ≤ 2 nm, and the tensile strength of the wire ≥ 7000 MPa.

3. A method for preparing a tungsten alloy wire as described in claim 1 or 2, characterized in that: It includes wet doping, powder making, pressing, sintering, blooming, hot working, and electrolytic cleaning.

4. The preparation method of the tungsten alloy wire according to claim 3, characterized in that: The wet doping is as follows: uniformly disperse blue tungsten powder in deionized water to obtain a blue tungsten suspension, uniformly disperse the nano - level compound powder of L in an alkaline solution with pH > 11 to form a second suspension, then spray the second suspension onto the blue tungsten suspension, and obtain doped blue tungsten powder after heating and drying; Preferably, the preparation method of the blue tungsten powder is: feed ammonium paratungstate into a reduction furnace, and carry out reduction under the protection of hydrogen and nitrogen at 400 - 600 °C to obtain blue tungsten powder, wherein the thickness of the ammonium paratungstate powder material layer is < 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 composition > 80%.

5. The preparation method of the tungsten alloy wire according to claim 3, characterized in that: The powder making is: reduce the doped blue tungsten powder to obtain alloy powder A with a particle size of 1.5 - 2.6 μm and alloy powder B with a particle size of 3.8 - 4.5 μm respectively, and then mix alloy powder A and alloy powder B to obtain a mixed powder; Preferably, the reduction method of alloy powder A is: first reduce the doped blue tungsten powder in a hydrogen reduction furnace at 500 - 800 °C, and then carry out secondary reduction in a hydrogen reduction furnace to obtain alloy powder A with a particle size of 1.5 - 2.6 μm; Preferably, the reduction method of alloy powder B is: reduce the doped blue tungsten powder in a hydrogen reduction furnace at 700 - 1100 °C to obtain alloy powder B with a particle size of 3.8 - 4.5 μm; Preferably, alloy powder A and alloy powder B are mixed in a mass ratio of 1:(1 - 2).

6. The preparation method of the tungsten alloy wire according to claim 3, wherein: The sintering is as follows: subjecting the pre-sintered blank bar obtained by pressing to high-temperature sintering at 2200 - 2800 °C.

7. The preparation method of the tungsten alloy wire according to claim 3, characterized in that: The hot working is as follows: subjecting the alloy rod obtained by cogging to recrystallization annealing, and then forging it into a tungsten rod with a diameter of 2.5 - 4.0 mm through a multi-pass continuous rotary forging device. The tungsten rod is subjected to rough drawing through wire drawing dies of different specifications, and the drawing pass reduction ratio of 35% - 60% is repeated multiple times to obtain a tungsten alloy thick wire with a diameter of 0.3 - 0.5 mm. Preferably, in the hot working, the alloy rod obtained by cogging is heated to 2000 - 2600 °C through a medium / high-frequency induction coil for recrystallization annealing.

8. The preparation method of the tungsten alloy wire according to claim 3, characterized in that: When the tungsten alloy wire is drawn to a diameter of 0.3 - 0.5 mm, it needs to be annealed at an annealing temperature of 1300 - 1700 °C. After annealing, the tungsten alloy wire is cooled in an oxygen environment. The cumulative processing deformation rate after annealing is ≥95%. After annealing, drawing is repeated multiple times to obtain tungsten alloy wires with different diameter specifications.

9. The preparation method of the tungsten alloy wire according to claim 3, characterized in that: The preparation method further includes electrolytic cleaning: subjecting the obtained tungsten alloy wire to high-concentration alkali solution and alternating current electrolysis first, and then to low-concentration alkali solution and direct current electrolysis. Preferably, the obtained tungsten alloy wire is first electrolyzed through a potassium hydroxide solution with a concentration of 20 wt% - 30 wt% and containing 8 - 15 groups of alternating current electrolysis sheets, and then electrolyzed successively through 5 - 8 groups of potassium hydroxide solutions with a concentration of 5 wt% - 10 wt% and containing 5 - 10 groups of direct current electrolysis sheets, and then the surface is cleaned with deionized water, wherein the electrolysis speed is 50 - 200 m / min.

10. An application of the tungsten alloy wire according to claim 1 or 2 in the fields of cutting, cutting resistance protection, cables, screen printing, ropes or textiles.

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