Preparation method of high-strength tungsten alloy wire with length exceeding 150km for photovoltaic silicon wafer cutting

Abstract

The invention discloses a preparation method of a high-strength tungsten alloy wire with the length exceeding 150 km for photovoltaic silicon wafer cutting, and belongs to the technical field of tungsten wire manufacturing. The preparation method of the high-strength tungsten alloy wire comprises the following steps that ammonium paratungstate and lanthanum oxide are added into water to obtain a mixed solution, and the mixed solution is dried, calcined and reduced to obtain mixed tungsten powder; pressing the mixed tungsten powder into a rod shape, and sintering to obtain a sintered tungsten rod; annealing the sintered tungsten rod to obtain a completely recrystallized rod, and performing rotary swaging to obtain a rotary swaged tungsten rod; drawing the rotary swaged tungsten rod to obtain a tungsten filament with the diameter of 0.37-0.41 mm, and annealing to obtain a tungsten filament A; drawing the tungsten filament A to obtain a tungsten filament with the diameter of 0.16-0.18 mm, and annealing to obtain a tungsten filament B; and drawing the tungsten filament B to obtain a tungsten filament with the diameter of 36-38 microns, namely the high-strength tungsten alloy wire. The invention discloses an annealing process in a tungsten alloy wire drawing process, which can effectively reduce the generation of defects such as cracks in a machining process.

Description

Technical Field

[0001] The invention relates to the technical field of tungsten wire manufacturing, and in particular to a method for preparing a high-strength tungsten alloy wire with a length exceeding 150 km for cutting photovoltaic silicon wafers. Background Art

[0002] The research and development of tungsten wire has a history of nearly 100 years. The earliest tungsten wire was mainly made by doping silicon oxide, potassium oxide and other oxides to make double-helix filaments with good high-temperature anti-droop performance. It was used for home lighting and there were no special requirements for the length and wire diameter of the tungsten wire. In recent years, with the continuous development of the photovoltaic industry, higher requirements have been put forward for silicon wafers, which have gradually shifted to larger and thinner sizes. However, the wire diameter of the carbon steel diamond wire commonly used in the market is close to the limit and cannot meet the current stringent requirements of silicon wafer cutting. Under the technical background of diamond wire thinning and silicon wafer thinning, tungsten alloy wire has gradually attracted attention due to its advantages of ultra-fineness and high strength. Tungsten diamond wire prepared with tungsten alloy wire as the mother wire has a thinner wire diameter, which can significantly reduce the generation of waste when cutting silicon materials, and has higher strength and durability. The overall cost performance is higher than that of carbon steel diamond wire. The trend of using tungsten wire to replace high-carbon steel wire as the mother wire of diamond wire has gradually become a development direction.

[0003] However, the current tungsten alloy wire preparation is difficult and has low breaking force, and there are problems such as easy wire breakage and low yield. Long tungsten wire can be used longer in silicon wafer cutting, reducing the frequency of replacement and improving production efficiency. However, the preparation of ultra-long tungsten alloy wire still needs to improve the relevant preparation and drawing processes, such as the type of strengthening phase, doping method and rotary forging, the timing of tungsten wire annealing process selection during drawing, annealing temperature, drawing pass, etc., to improve the comprehensive performance of tungsten wire. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a high-strength tungsten alloy wire with a length of more than 150 km for photovoltaic silicon wafer cutting, so as to solve the above-mentioned problems in the background technology. The present invention discloses an annealing process in the drawing process of tungsten alloy wire. The appropriate annealing time and process can effectively reduce the generation of defects such as cracks in the processing process and reduce the wire breakage rate. The breaking force of the prepared tungsten alloy wire reaches 6.5N and the length exceeds 150km, realizing the ultra-long preparation of high-strength tungsten alloy wire.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] One of the technical solutions of the present invention is to provide a method for preparing a high-strength tungsten alloy wire, comprising the following steps:

[0007] (1) adding ammonium paratungstate and lanthanum oxide into water to obtain a mixed solution, drying, calcining, and reducing to obtain a mixed tungsten powder;

[0008] (2) pressing the mixed tungsten powder into a rod shape, sintering, and obtaining a sintered tungsten rod; annealing the sintered tungsten rod to obtain a completely recrystallized rod, and rotary forging to obtain a rotary forged tungsten rod;

[0009] (3) drawing the rotary forged tungsten rod to obtain a tungsten wire with a diameter of 0.37 to 0.41 mm, and annealing to obtain a tungsten wire A;

[0010] (4) drawing the tungsten wire A to obtain a tungsten wire with a diameter of 0.16 to 0.18 mm, and annealing to obtain a tungsten wire B;

[0011] (5) Drawing the tungsten wire B to obtain a tungsten wire with a diameter of 36 to 38 μm, namely the high-strength tungsten alloy wire.

[0012] Preferably, the diameter of the sintered tungsten rod is 22-23 mm.

[0013] Preferably, after obtaining the sintered tungsten rod, the steps of forging and straightening are also included; the forging temperature of the forged billet is 1600-1700°C, and the diameter of the tungsten rod after forging is 17-18mm; the straightening is performed by a Y-type rolling mill for multiple passes, and the cross-sectional deformation of each pass is 15-20%, and the diameter is rolled to 8-9mm.

[0014] Preferably, the method for drawing the rotary forged tungsten rod is: chain drawing the rotary forged tungsten rod to a diameter of 3 mm, and then single-mode drawing through multiple large, medium and small turntables to draw a 0.66 mm thick tungsten wire, and then multi-mode drawing to a diameter of 0.37-0.41 mm. In order to improve its toughness and prevent the tungsten alloy wire from breaking during the drawing process, natural gas heating is used; in order to prevent surface oxidation, the drawing process is carried out in an atmosphere protected by inert gas.

[0015] Preferably, during the drawing process of step (3), the heating temperature is 600-900°C.

[0016] Preferably, during the drawing process of step (4), the heating temperature is 500-700°C.

[0017] Preferably, during the drawing process of step (5), the heating temperature is 500-700°C.

[0018] Preferably, during the drawing process, in order to prevent surface cracks, wire shrinkage, wire breakage, etc., small passes are used and graphite emulsion lubrication is added.

[0019] Preferably, the content of lanthanum oxide in the mixed tungsten powder is 0.55-0.85wt.%; the calcination temperature is 200-400°C and the time is 2h; the reduction is carried out in a hydrogen atmosphere at 600-650°C for 1h and then at 850-900°C for 1h.

[0020] Preferably, in step (2), the sintering temperature is 2300-2400° C., the time is 5-8 hours, and the atmosphere is a hydrogen atmosphere; the annealing temperature is 1800-1900° C., and the time is 30-60 minutes;

[0021] In step (3): the annealing temperature is 1400-1500° C. and the time is 20-30 min;

[0022] In step (4): the annealing temperature is 1400-1600° C. and the time is 20-30 min.

[0023] Preferably, the single cross-sectional shrinkage deformation of the rotary forging is 10-15%, and the diameter of the rotary forging tungsten rod is 5 mm.

[0024] The second technical solution of the present invention is to provide a high-strength tungsten alloy wire obtained according to the above preparation method.

[0025] Preferably, the length of the high-strength tungsten alloy wire is ≥150 km, and the breaking force is ≥6.5N.

[0026] The third technical solution of the present invention is to provide an application of the above-mentioned high-strength tungsten alloy wire in the field of silicon wafer cutting.

[0027] The technical principles of the present invention are as follows:

[0028] The high-strength tungsten alloy wire preparation process disclosed in the present invention comprises the following steps in sequence: liquid-liquid doping, hydrogen reduction, cold pressing of blanks, high-temperature sintering, rotary forging, multi-type and multi-pass drawing, etc. The present invention particularly relates to a related node annealing process in the drawing process.

[0029] The present invention adopts liquid-liquid doping to prepare tungsten alloy rod blanks, and develops a method for preparing ultra-long and high-strength tungsten wire by combining multiple processes such as rotary forging, multi-type multi-pass drawing, and key node annealing. The length of the tungsten wire can reach more than 150km, and the breaking force exceeds 6.5N, which meets the requirements of high-performance tungsten wire. The material of high-strength tungsten alloy wire is micro-lanthanum tungsten alloy.

[0030] The beneficial technical effects of the present invention are as follows:

[0031] The present invention takes second phase strengthening and fine grain strengthening as strengthening ideas, and adopts wet chemical liquid-liquid doping method to prepare tungsten alloy wire. Compared with traditional solid-solid doping, it can realize the uniform distribution of micro-lanthanum in tungsten alloy from the source, and the doping of micro-lanthanum can realize the sintering densification of tungsten alloy. In the subsequent processing process, lanthanum oxide can also play a role in hindering grain boundary migration and pinning dislocation movement, so as to achieve the purpose of fine grain strengthening and dispersion strengthening, thereby improving the strength and toughness of tungsten wire. In addition, the present invention discloses the annealing process in the drawing process of tungsten alloy wire. The appropriate annealing time and process can effectively reduce the generation of defects such as cracks in the processing process, reduce the wire breakage rate, and prepare ultra-long high-strength tungsten wire. The prepared tungsten alloy wire has a breaking force of 6.5N and a length of more than 150km, realizing the ultra-long preparation of high-strength tungsten alloy wire. Its length and breaking force are significantly higher than ordinary carbon steel wire and pure tungsten wire, meeting the breaking force requirement (5.6N) of wire saw diamond wire busbar, and tungsten alloy wire can be used to cut hard materials such as silicon material and sapphire. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 This is the SEM image of the fully recrystallized rod in Example 1.

[0034] Figure 2 This is the SEM image of the high-strength tungsten alloy wire in Example 1.

[0035] Figure 3 It is a comparison chart of the breaking force of the products of Examples 1-3 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0036] Now, various exemplary embodiments of the present invention are described in detail, and this detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present invention. It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention.

[0037] In addition, for the numerical range in the present invention, it is understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0038] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the invention pertains. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention.

[0039] The words “include,” “including,” “have,” “contain,” etc. used in the present invention are open-ended terms, meaning including but not limited to.

[0040] The drawing processes in the following embodiments and comparative examples of the present invention are all carried out in an atmosphere protected by an inert gas.

[0041] All raw materials used in the following examples and comparative examples of the present invention are commercially available products.

[0042] Example 1

[0043] A method for preparing high-strength tungsten alloy wire:

[0044] (1) Ammonium paratungstate and lanthanum oxide colloid were fully stirred and mixed in water for 24 hours. Dry, then calcine at 200℃ for 2 hours, and then hydrogen reduced at 620℃ and 880℃ for 1 hour in a hydrogen atmosphere to obtain mixed tungsten powder (the content of lanthanum oxide in the mixed tungsten powder is 0.60wt.%, and the rest is tungsten powder). The mixed tungsten powder was loaded into a rod-shaped rubber mold and cold isostatically pressed at 180MPa to form a rod-shaped tungsten billet; sintered in a medium-frequency induction sintering furnace in a hydrogen atmosphere, the sintering temperature was 2350℃, the sintering time was 5 hours, and the diameter of the sintered tungsten billet was 22mm.

[0045] (2) Forging the sintered tungsten rod blank in step (1) to open the blank, the opening temperature is 1650° C., and the diameter of the tungsten rod after forging is 17.5 mm; further straightening the tungsten rod by a Y-type rolling mill for multiple passes, with a cross-sectional deformation of 15-20% in each pass, until the diameter is 8 mm; further medium-frequency induction annealing is performed on the tungsten rod to achieve a degree of complete recrystallization, wherein the annealing temperature is 1800° C. and the annealing time is 60 min to obtain a completely recrystallized rod; further, the completely recrystallized rod is repeatedly forged to a thin tungsten rod with a diameter of 5 mm, and the single cross-sectional deformation is 10-15%.

[0046] (3) Chain drawing the thin tungsten rod in step (2) at 850°C until the diameter is 3 mm; further, the thin tungsten rod is subjected to single-mode wire drawing through multiple large, medium and small turntables to be drawn into a 0.66 mm thick tungsten wire. Then, multi-mode wire drawing is used to draw the tungsten wire until the diameter is 0.39 mm.

[0047] (4) The 0.39 mm thick tungsten wire in step (3) is subjected to stress relief annealing at a temperature of 1500°C for 30 minutes; the 0.39 mm tungsten wire is further subjected to multi-mode drawing at 650°C for multiple passes to a tungsten wire with a wire diameter of 0.16 mm. The 0.16 mm diameter tungsten wire is subjected to annealing at a temperature of 1550°C for 20 minutes; further, multiple drawing is performed at 550°C until the final diameter of the tungsten wire is 37.5 μm. After the drawing is completed, electrolytic polishing is performed for whitening; the final length of the high-strength tungsten alloy wire is 165 km. After tensile testing, the breaking force of the high-strength tungsten alloy wire reaches 6.43 N, which is greater than the breaking force of 5.6 N required for wire cutting.

[0048] During the drawing process of steps (3) and (4), in order to prevent surface cracks, wire shrinkage, wire breakage, etc., a small compression ratio multi-pass drawing and the addition of graphite emulsion lubrication are adopted; the parameters of the small compression ratio multi-pass drawing are: the compression ratio of 3 to 0.66 mm is 20 to 25%, the compression ratio of 0.66 to 0.39 mm is 15 to 20%, the compression ratio of 0.39 to 0.16 mm is 10 to 15%, and the compression ratio of 0.16 to 0.0375 mm is 8 to 10%.

[0049] The SEM image of the 8 mm diameter tungsten rod after complete recrystallization annealing in step (2) is as follows: Figure 1 shown.

[0050] Figure 1 This is the SEM image of the fully recrystallized rod in Example 1.

[0051] Figure 2 This is the SEM image of the high-strength tungsten alloy wire in Example 1.

[0052] Example 2

[0053] A method for preparing high-strength tungsten alloy wire:

[0054] (1) Ammonium paratungstate and lanthanum oxide colloid were fully stirred and mixed in water for 24 hours. Dry, then calcine at 200℃ for 2 hours, and then hydrogen reduced at 640℃ and 850℃ for 1 hour in a hydrogen atmosphere to obtain mixed tungsten powder (the content of lanthanum oxide in the mixed tungsten powder is 0.72wt.%, and the rest is tungsten powder). The mixed tungsten powder was loaded into a rod-shaped rubber mold and cold isostatically pressed at 180MPa to form a rod-shaped tungsten billet; sintered in a medium-frequency induction sintering furnace in a hydrogen atmosphere, the sintering temperature was 2350℃, the sintering time was 5 hours, and the diameter of the sintered tungsten billet was 22mm.

[0055] (2) Forging the sintered tungsten rod blank in step (1) to open the blank, the opening temperature is 1650° C., and the diameter of the tungsten rod after forging is 17.5 mm; further straightening the tungsten rod by a Y-type rolling mill for multiple passes, with a cross-sectional deformation of 15-20% in each pass, until the diameter is 8 mm; further medium-frequency induction annealing is performed on the tungsten rod to achieve complete recrystallization, wherein the annealing temperature is 1850° C. and the annealing time is 60 min; further the completely recrystallized rod is repeatedly rotary forged to a thin tungsten rod with a diameter of 5 mm, and the single cross-sectional deformation is 10-15%.

[0056] (3) Under heating at 860° C., the thin tungsten rod in step (2) is chain-drawn to a diameter of 3 mm; the thin tungsten rod is further single-mode drawn through multiple large, medium and small turntables to a 0.66 mm thick tungsten wire. Then, multi-mode drawing is used to draw the tungsten wire until the diameter is 0.39 mm.

[0057] (4) The 0.39 mm thick tungsten wire in step (3) is subjected to stress relief annealing at a temperature of 1500°C for 30 minutes; the 0.39 mm tungsten wire is further heated at 670°C and subjected to multi-mode drawing to a tungsten wire with a wire diameter of 0.16 mm. The 0.16 mm diameter tungsten wire is annealed at a temperature of 1550°C for 20 minutes; it is further drawn at 540°C until the final diameter of the tungsten wire is 38 μm. After the drawing is completed, it is electrolytically polished for whitening; the final length of the high-strength tungsten alloy wire is 160 km. After tensile testing, the breaking force of the high-strength tungsten alloy wire reaches 6.49 N, which is greater than the breaking force of 5.6 N required for wire cutting.

[0058] During the drawing process of steps (3) and (4), in order to prevent surface cracks, wire shrinkage, wire breakage, etc., a small compression ratio multi-pass drawing and the addition of graphite emulsion lubrication are adopted; the parameters of the small compression ratio multi-pass drawing are: the compression ratio of 3 to 0.66 mm is 20 to 25%, the compression ratio of 0.66 to 0.39 mm is 15 to 20%, the compression ratio of 0.39 to 0.16 mm is 10 to 15%, and the compression ratio of 0.16 to 0.038 mm is 8 to 10%.

[0059] Example 3

[0060] A method for preparing high-strength tungsten alloy wire:

[0061] (1) Ammonium paratungstate and lanthanum oxide colloid were fully stirred and mixed in water for 24 hours. Dry, then calcine at 200℃ for 2 hours, and then hydrogen reduced at 640℃ and 900℃ for 1 hour in a hydrogen atmosphere to obtain mixed tungsten powder (the content of lanthanum oxide in the mixed tungsten powder is 0.58wt.%, and the rest is tungsten powder). The mixed tungsten powder was loaded into a rod-shaped rubber mold and cold isostatically pressed at 180MPa to form a rod-shaped tungsten billet; sintered in a medium-frequency induction sintering furnace in a hydrogen atmosphere, the sintering temperature was 2350℃, the sintering time was 6 hours, and the diameter of the sintered tungsten billet was 22mm.

[0062] (2) The sintered tungsten rod blank in step (1) is forged to be opened, the opening temperature is 1650° C., and the diameter of the tungsten rod after forging is 17.5 mm; the tungsten rod is further straightened by a Y-type rolling mill for multiple passes, and the cross-sectional deformation of each pass is 15-20%, and the diameter is rolled to 8 mm; the tungsten rod is further subjected to medium frequency induction annealing to achieve a degree of complete recrystallization, wherein the annealing temperature is 1800° C. and the annealing time is 60 min; the completely recrystallized rod is further subjected to multiple rotary forgings to a thin tungsten rod with a diameter of 5 mm, and the single cross-sectional deformation is 10-15%.

[0063] (3) The thin tungsten rod in step (2) is chain-drawn at 800°C until the diameter is 3 mm; the thin tungsten rod is further single-mode drawn through multiple large, medium and small turntables to a 0.66 mm thick tungsten wire. Then, multi-mode drawing is used to draw the tungsten wire until the diameter is 0.39 mm.

[0064] (4) The 0.39 mm thick tungsten wire in step (3) is subjected to stress relief annealing at a temperature of 1500°C for 30 minutes; the 0.39 mm tungsten wire is further subjected to multi-mode drawing at 630°C for multiple passes to a tungsten wire with a wire diameter of 0.16 mm. The 0.16 mm diameter tungsten wire is subjected to annealing at a temperature of 1550°C for 20 minutes; further, multiple drawing is performed at 520°C until the final diameter of the tungsten wire is 36.5 μm. After the drawing is completed, electrolytic polishing is performed for whitening; the final length of the high-strength tungsten alloy wire reaches 160 km. After tensile testing, the breaking force of the high-strength tungsten alloy wire reaches 6.51 N, which is greater than the breaking force of 5.6 N required for wire cutting.

[0065] During the drawing process of steps (3) and (4), in order to prevent surface cracks, wire shrinkage, wire breakage, etc., a small compression ratio multi-pass drawing and the addition of graphite emulsion lubrication are adopted; the parameters of the small compression ratio multi-pass drawing are: the compression ratio of 3 to 0.66 mm is 20 to 25%, the compression ratio of 0.66 to 0.39 mm is 15 to 20%, the compression ratio of 0.39 to 0.16 mm is 10 to 15%, and the compression ratio of 0.16 to 0.0365 mm is 8 to 10%.

[0066] Comparative Example 1

[0067] A method for preparing high-strength tungsten alloy wire:

[0068] (1) Ammonium paratungstate and lanthanum oxide colloid were fully stirred and mixed in water for 24 hours. Dry, then calcine at 200℃ for 2 hours, and then hydrogen reduced at 640℃ and 900℃ for 1 hour in a hydrogen atmosphere to obtain mixed tungsten powder (the content of lanthanum oxide in the mixed tungsten powder is 1.20wt.%, and the rest is tungsten powder). The mixed tungsten powder was loaded into a rod-shaped rubber mold and cold isostatically pressed at 180MPa to form a rod-shaped tungsten billet; sintered in a medium-frequency induction sintering furnace in a hydrogen atmosphere, the sintering temperature was 2350℃, the sintering time was 6 hours, and the diameter of the sintered tungsten billet was 22mm.

[0069] (2) The sintered tungsten rod blank in step (1) is forged to be opened, the opening temperature is 1650° C., and the diameter of the tungsten rod after forging is 17.5 mm; the tungsten rod is further straightened by a Y-type rolling mill for multiple passes, and the cross-sectional deformation of each pass is 15-20%, and the diameter is rolled to 8 mm; the tungsten rod is further subjected to medium frequency induction annealing to achieve a degree of complete recrystallization, wherein the annealing temperature is 1800° C. and the annealing time is 60 min; the completely recrystallized rod is further subjected to multiple rotary forgings to a thin tungsten rod with a diameter of 5 mm, and the single cross-sectional deformation is 10-15%.

[0070] (3) Under heating at 820° C., the thin tungsten rod in step (2) is chain-drawn to a diameter of 3 mm; the thin tungsten rod is further single-mode drawn through multiple large, medium and small turntables to a 0.66 mm thick tungsten wire. Then, multi-mode drawing is used to draw the tungsten wire until the diameter is 0.39 mm.

[0071] (4) The 0.39 mm thick tungsten wire in step (3) is subjected to stress relief annealing at a temperature of 1500°C for 30 minutes; the 0.39 mm tungsten wire is further heated at 630°C and subjected to multi-mode drawing to a tungsten wire with a wire diameter of 0.16 mm. The 0.16 mm diameter tungsten wire is annealed at a temperature of 1600°C for 20 minutes; it is further drawn at 510°C for multiple passes until the final diameter of the tungsten wire is 37.5 μm, and electrolytic polishing is performed after the drawing is completed; the final length of the high-strength tungsten alloy wire is only 83 km. After tensile testing, the breaking force of the high-strength tungsten alloy wire is only 5.63N.

[0072] During the drawing process of steps (3) and (4), in order to prevent surface cracks, wire shrinkage, wire breakage, etc., a small compression ratio multi-pass drawing and the addition of graphite emulsion lubrication are adopted; the parameters of the small compression ratio multi-pass drawing are: the compression ratio of 3 to 0.66 mm is 20 to 25%, the compression ratio of 0.66 to 0.39 mm is 15 to 20%, the compression ratio of 0.39 to 0.16 mm is 10 to 15%, and the compression ratio of 0.16 to 0.0375 mm is 8 to 10%.

[0073] Comparative Example 2

[0074] A method for preparing high-strength tungsten alloy wire:

[0075] (1) Ammonium paratungstate and lanthanum oxide colloid were fully stirred and mixed in water for 24 hours. Dry, then calcine at 200℃ for 2 hours, and then hydrogen reduced at 640℃ and 900℃ for 1 hour in a hydrogen atmosphere to obtain mixed tungsten powder (the content of lanthanum oxide in the mixed tungsten powder is 1.00wt.%, and the rest is tungsten powder). The mixed tungsten powder was loaded into a rod-shaped rubber mold and cold isostatically pressed at 180MPa to form a rod-shaped tungsten billet; sintered in a medium-frequency induction sintering furnace in a hydrogen atmosphere, the sintering temperature was 2350℃, the sintering time was 6 hours, and the diameter of the sintered tungsten billet was 22mm.

[0076] (2) The sintered tungsten rod blank in step (1) is forged to be opened, the opening temperature is 1650° C., and the diameter of the tungsten rod after forging is 17.5 mm; the tungsten rod is further straightened by a Y-type rolling mill for multiple passes, and the cross-sectional deformation of each pass is 15-20%, and the diameter is rolled to 8 mm; the tungsten rod is further subjected to medium frequency induction annealing to achieve a degree of complete recrystallization, wherein the annealing temperature is 1800° C. and the annealing time is 60 min; the completely recrystallized rod is further subjected to multiple rotary forgings to a thin tungsten rod with a diameter of 5 mm, and the single cross-sectional deformation is 10-15%.

[0077] (3) Under heating at 780° C., the thin tungsten rod in step (2) is chain-drawn to a diameter of 3 mm; the thin tungsten rod is further single-mode drawn through multiple large, medium and small turntables to a 0.66 mm thick tungsten wire. Then, multi-mode drawing is used to draw the tungsten wire until the diameter is 0.39 mm.

[0078] (4) The 0.39 mm thick tungsten wire in step (3) is subjected to stress relief annealing at a temperature of 1500°C for 30 minutes; the 0.39 mm tungsten wire is further heated at 640°C and subjected to multi-mode drawing to a tungsten wire with a wire diameter of 0.16 mm. The 0.16 mm diameter tungsten wire is annealed at a temperature of 1450°C for 20 minutes; it is further drawn at 500°C for multiple passes until the final diameter of the tungsten wire is 36.5 μm, and electrolytic polishing is performed after the drawing is completed; the final length of the high-strength tungsten alloy wire is only 125 km. After tensile testing, the breaking force of the high-strength tungsten alloy wire is only 5.62N.

[0079] During the drawing process of steps (3) and (4), in order to prevent surface cracks, wire shrinkage, wire breakage, etc., a small compression ratio multi-pass drawing and the addition of graphite emulsion lubrication are adopted; the parameters of the small compression ratio multi-pass drawing are: the compression ratio of 3 to 0.66 mm is 20 to 25%, the compression ratio of 0.66 to 0.39 mm is 15 to 20%, the compression ratio of 0.39 to 0.16 mm is 10 to 15%, and the compression ratio of 0.16 to 0.0365 mm is 8 to 10%.

[0080] Figure 3 It is a comparison chart of the breaking force of the products of Examples 1-3 and Comparative Examples 1-2.

[0081] Effect verification

[0082] Performance test: The products prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to breaking force tests under the same test conditions. The relevant parameters and breaking force comparison are shown in Table 1.

[0083] Table 1

[0084] sample Wire diameter(mm) Length (km) Stretching speed (mm / min) Breaking force(N) Example 1 37.5μm 155 10 6.43 Example 2 38μm 160 10 6.49 Example 3 36.5μm 160 10 6.51 Comparative Example 1 37.5μm 80 10 5.63 Comparative Example 2 36.5μm 120 10 5.62

[0085] As shown in Table 1, when the amount of lanthanum oxide added is within the range specified by the present invention, a high-strength tungsten wire with a length of more than 150 km and a breaking force of more than 6.43 N can be prepared by combining sintering, drawing and annealing processes; as the amount of lanthanum oxide doping increases, the breaking force is significantly reduced, and the problem of tungsten wire length not meeting the standard occurs. This may be because, in the preparation scheme specified by the present invention, an excessively high lanthanum oxide content may cause it to aggregate in the tungsten alloy, affecting the strengthening effect of the tungsten alloy, and ultimately causing the tungsten wire to break easily during the drawing process.

[0086] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing high-strength tungsten alloy wire, characterized in that: The following steps are involved: (1) adding ammonium paratungstate and lanthanum oxide into water to obtain a mixed solution, drying, calcining, and reducing to obtain a mixed tungsten powder; (2) pressing the mixed tungsten powder into a rod shape, sintering, and obtaining a sintered tungsten rod; annealing the sintered tungsten rod to obtain a completely recrystallized rod, and rotary forging to obtain a rotary forged tungsten rod; (3) drawing the rotary forged tungsten rod to obtain a tungsten wire with a diameter of 0.37 to 0.41 mm, and annealing to obtain a tungsten wire A; (4) drawing the tungsten wire A to obtain a tungsten wire with a diameter of 0.16 to 0.18 mm, and annealing to obtain a tungsten wire B; (5) Drawing the tungsten wire B to obtain a tungsten wire with a diameter of 36 to 38 μm, namely the high-strength tungsten alloy wire.

2. The preparation method according to claim 1, characterized in that: The content of lanthanum oxide in the mixed tungsten powder is 0.55-0.85wt.%; the calcination temperature is 200-400°C and the time is 2h; the reduction is carried out in a hydrogen atmosphere at 600-650°C for 1h and then at 850-900°C for 1h.

3. The preparation method according to claim 1, characterized in that: In step (2), the sintering temperature is 2300-2400° C., the time is 5-8 hours, and the atmosphere is a hydrogen atmosphere; the annealing temperature is 1800-1900° C., and the time is 30-60 minutes; In step (3): the annealing temperature is 1400-1500° C. and the time is 20-30 min; In step (4): the annealing temperature is 1400-1600° C. and the time is 20-30 min.

4. A high-strength tungsten alloy wire obtained according to the preparation method according to any one of claims 1 to 3.

5. Application of the high-strength tungsten alloy wire according to claim 4 in the field of silicon wafer cutting.

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