WO2023228833A1 - Tungsten wire - Google Patents

Tungsten wire Download PDF

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Publication number
WO2023228833A1
WO2023228833A1 PCT/JP2023/018418 JP2023018418W WO2023228833A1 WO 2023228833 A1 WO2023228833 A1 WO 2023228833A1 JP 2023018418 W JP2023018418 W JP 2023018418W WO 2023228833 A1 WO2023228833 A1 WO 2023228833A1
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Prior art keywords
wire
tungsten
tungsten wire
tensile strength
content
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PCT/JP2023/018418
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French (fr)
Japanese (ja)
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和宏 大條
直樹 神山
吉弘 児玉
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パナソニックＩｐマネジメント株式会社
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Publication of WO2023228833A1 publication Critical patent/WO2023228833A1/en

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C27/00—Alloys based on rhenium or a refractory metal not mentioned in groups C22C14/00 or C22C16/00
    • C22C27/04—Alloys based on tungsten or molybdenum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
    • C22F1/18—High-melting or refractory metals or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working

Definitions

  • the present invention relates to tungsten wire.
  • Patent Document 1 discloses a tungsten wire with a tensile strength of 4800 MPa or more.
  • an object of the present invention is to provide a tungsten wire with improved circularity.
  • a tungsten wire according to one embodiment of the present invention contains tungsten as a main component.
  • tensile strength is T (unit: MPa) and wire diameter is D (unit: mm)
  • wire diameter is D (unit: mm)
  • 4758 ⁇ D 2 -7258.3 ⁇ D+5275.5 ⁇ T ⁇ 4758 ⁇ D 2 -7258.3 ⁇ D+6100 satisfy.
  • the roundness of the tungsten wire is 2.0% or less.
  • a tungsten wire with improved circularity can be realized.
  • FIG. 1 is a schematic diagram showing the appearance and cross section of a tungsten wire according to an embodiment.
  • FIG. 2 is a diagram for explaining roundness.
  • FIG. 3 is a flowchart illustrating an example of a method for manufacturing a tungsten wire according to an embodiment.
  • FIG. 4 is a flowchart showing another example of the method for manufacturing a tungsten wire according to the embodiment.
  • FIG. 5 is a diagram showing the relationship between the wire diameter and tensile strength of a tungsten wire containing rhenium or cerium.
  • FIG. 6 is a diagram showing the relationship between rhenium content, tensile strength, and circularity for a tungsten wire containing rhenium and having a wire diameter of 50 ⁇ m.
  • FIG. 1 is a schematic diagram showing the appearance and cross section of a tungsten wire according to an embodiment.
  • FIG. 2 is a diagram for explaining roundness.
  • FIG. 3 is a flowchart illustrating an example of a
  • FIG. 7 is a diagram showing the relationship between rhenium content, tensile strength, and circularity for a tungsten wire containing rhenium and having a wire diameter of 30 ⁇ m.
  • FIG. 8 is a diagram showing the relationship between cerium content, tensile strength, and circularity for a tungsten wire containing cerium and having a wire diameter of 30 ⁇ m.
  • each figure is a schematic diagram and is not necessarily strictly illustrated. Therefore, for example, the scales and the like in each figure do not necessarily match. Further, in each figure, substantially the same configurations are denoted by the same reference numerals, and overlapping explanations will be omitted or simplified.
  • FIG. 1 is a schematic diagram showing the appearance and cross section of a tungsten wire 1 according to the present embodiment.
  • the tungsten wire 1 is wound around a winding frame 2 and stored.
  • the winding frame 2 is sometimes referred to as a bobbin, reel, spool, or drum.
  • the tungsten wire 1 has a total length on the order of km, for example, 50 km or more and 300 km or less.
  • the tungsten wire 1 shown in FIG. 1 is used for manufacturing tungsten products.
  • the tungsten wire 1 is used as a core wire of a saw wire.
  • the saw wire is a wire of a fixed abrasive type, and includes a tungsten wire 1 as a core wire, and further includes abrasive grains such as diamond particles or cubic boron nitride (CBN) particles.
  • the abrasive grains are fixed to the surface of the tungsten wire 1.
  • the fixing may be by electrodeposition or by resin bonding.
  • the saw wire may be a loose abrasive type wire.
  • the saw wire may be the tungsten wire 1 itself without any abrasive grains.
  • Saw wires are used, for example, to cut semiconductor ingots such as silicon (Si) or silicon carbide (SiC).
  • Semiconductor wafers can be manufactured by slicing a semiconductor ingot with a saw wire. At this time, the smaller the wire diameter of the saw wire, the smaller the cutting allowance, which reduces loss and increases the number of wafers to be taken.
  • the object to be cut is not limited to a semiconductor ingot, and may be glass, concrete, crystal, ceramics, or the like.
  • the tungsten wire 1 contains tungsten (W) as a main component.
  • "Main component” means that the content (content rate) of the element is more than 50 wt%.
  • the content of tungsten contained in the tungsten wire 1 is 97 wt% or more.
  • the content of tungsten contained in the tungsten wire 1 may be 99 wt% or more, 99.9 wt% or more, or 99.99 wt% or more.
  • the tungsten wire 1 may also contain unavoidable impurities that are unavoidably mixed in during the manufacturing process.
  • the tungsten wire 1 contains, for example, rhenium (Re).
  • the content of rhenium in the tungsten wire 1 is, for example, 0.1 wt% or more and 3 wt% or less.
  • Rhenium constitutes an alloy (solid solution) with tungsten.
  • the tensile strength of the tungsten wire 1 can be increased.
  • the rhenium content is too high, it is difficult to thin the tungsten wire 1 while maintaining its high tensile strength. Specifically, wire breaks are more likely to occur, making it difficult to draw long wires.
  • the workability of the tungsten wire 1 can be improved. Furthermore, by reducing the content of rare and expensive rhenium, it becomes possible to mass produce long, inexpensive tungsten wires 1.
  • the metal used for the alloy with tungsten may be osmium (Os), ruthenium (Ru), or iridium (Ir).
  • the content of osmium, ruthenium or iridium is similar to the content of rhenium, for example. In these cases, the same effects as in the case of rhenium-tungsten alloy can be obtained.
  • the tungsten wire 1 may be made of an alloy of tungsten and two or more metals other than tungsten.
  • the tungsten wire 1 may contain potassium (K).
  • the potassium content in the tungsten wire 1 is, for example, 0.001 wt% or more and 0.01 wt% or less. Potassium exists at the grain boundaries of tungsten. Even the tungsten wire 1 containing potassium can achieve a tensile strength higher than the general tensile strength of piano wire.
  • the tungsten wire 1 may contain a rare earth element.
  • the content of rare earth elements in the tungsten wire 1 is, for example, 0.03 wt% or more and 0.3 wt% or less.
  • the content of rare earth elements in the tungsten wire 1 may be, for example, 0.03 wt% or more and 0.09 wt% or less.
  • Examples of rare earth elements include cerium (Ce), lanthanum (La), yttrium (Y), and samarium (Sm). Rare earth elements are present at the grain boundaries of tungsten. Even the tungsten wire 1 containing rare earth elements can achieve a tensile strength higher than the general tensile strength of piano wire.
  • the wire diameter of the tungsten wire 1 is 100 ⁇ m or less.
  • the wire diameter of the tungsten wire 1 may be 80 ⁇ m or less, 70 ⁇ m or less, 60 ⁇ m or less, 50 ⁇ m or less, 40 ⁇ m or less, 30 ⁇ m or less It may be 20 ⁇ m or less, or 15 ⁇ m or less. Further, according to the manufacturing method described later, a tungsten wire 1 having an extremely thin wire diameter of 13 ⁇ m or less can also be realized.
  • the wire diameter of the tungsten wire 1 may be 10 ⁇ m or less, 8 ⁇ m or less, or 7 ⁇ m or less.
  • the wire diameter of the tungsten wire 1 is, for example, 5 ⁇ m or more, but is not limited thereto.
  • the tensile strength of the tungsten wire 1 is 4800 MPa or more.
  • the tensile strength may be 4900 MPa or more, 5000 MPa or more, 5200 MPa or more, or 5500 MPa or more.
  • a tungsten wire 1 having an extremely high tensile strength of 5800 MPa or more is also realized.
  • the tensile strength of the tungsten wire 1 may be 5900 MPa or more, or 6000 MPa or more.
  • the tensile strength can be measured, for example, based on the Japanese Industrial Standards tensile test (JIS H 4460 8).
  • the tungsten wire 1 according to the present embodiment satisfies a predetermined relationship where the tensile strength is T (unit: MPa) and the wire diameter is D (unit: mm). Specifically, the tungsten wire 1 has been realized which has higher tensile strength than the conventional wire depending on the wire diameter.
  • the specific relationship between the tensile strength T and the wire diameter D will be explained later using FIG. 5 along with specific examples.
  • the circularity of the tungsten wire 1 is 2.0% or less. That is, the shape of the cross section of the tungsten wire 1 (the cross section perpendicular to the wire axis direction) has a shape sufficiently close to a perfect circle. In addition, in FIG. 1, the difference between the cross section of the tungsten wire 1 and the perfect circle is exaggerated.
  • FIG. 2 is a diagram for explaining roundness.
  • the circularity is an index representing the size of deviation of the cross-sectional shape of the tungsten wire 1 from a perfect circle.
  • the circularity f (unit: %) is expressed by the following formula (1).
  • a and B are as shown in FIG. 2. Specifically, first, a maximum inscribed circle and a minimum circumscribed circle are defined for the cross section of the tungsten wire 1.
  • the maximum inscribed circle and the minimum circumscribed circle are defined to be concentric circles and to minimize the distance between them. That is, if the radius of the minimum circumscribed circle is r(A) and the radius of the maximum inscribed circle is r(B), then r(A)-r(B) is the minimum.
  • A is the diameter of the minimum circumscribed circle and is expressed as 2 ⁇ r(A).
  • B is the diameter of the maximum inscribed circle and is expressed as 2 ⁇ r(B).
  • a tungsten wire 1 that has higher tensile strength depending on the wire diameter than conventional wires and has improved roundness (that is, the cross section is close to a perfect circle).
  • the roundness is improved, and variations in the thickness of sliced objects (wafers) can be suppressed.
  • TTV Total Thickness Variation
  • FIGS. 3 and 4 are flowcharts each showing an example of the method for manufacturing the tungsten wire 1 according to the present embodiment.
  • additives are added to tungsten (S10).
  • tungsten for example, only an additive (doping element) or a compound containing the additive (for example, an oxide or an aqueous solution) is added to a predetermined amount of tungsten powder.
  • the doping element is rhenium, potassium, or a rare earth element such as cerium or lanthanum. Unnecessary components contained in the compound are removed by subsequent sintering or the like.
  • the amount of doping element added is adjusted by adding tungsten powder at a predetermined ratio to the obtained doped tungsten powder. That is, the doping element may be added in an amount greater than the intended content of the doping element.
  • the tungsten powder can be added to dilute the dope element (reduce the content). That is, in the doping element addition step, the amount to be treated can be small, so a small addition device can be used. Furthermore, since a large amount of doped tungsten powder can be obtained in one addition process, the number of steps required for the addition process can be reduced. Thereby, productivity of the tungsten wire 1 can be improved.
  • a tungsten ingot is produced by pressing and sintering the obtained doped tungsten powder aggregate (S12).
  • a swaging process is performed on the produced tungsten ingot (S14). Specifically, a tungsten ingot is forged and compressed from its periphery and expanded to form a wire-like tungsten wire. Rolling may be performed instead of swaging.
  • a tungsten ingot with a diameter of about 15 mm or more and about 25 mm or less is formed into a tungsten wire with a wire diameter of about 3 mm or more and 4 mm or less.
  • the annealing treatment is performed at 2000° C. or more and 2400° C. or less in a diameter range of 8 mm or more and 10 mm or less.
  • annealing is not performed in the swaging process for diameters of less than 8 mm.
  • the tungsten wire is heated at 900° C. before heating wire drawing (S16). Specifically, the tungsten wire is directly heated with a burner or the like. By heating the tungsten wire, an oxide layer is formed on the surface of the tungsten wire to prevent the wire from breaking during subsequent heating wire drawing.
  • heating wire drawing is performed (S18). Specifically, the tungsten wire is drawn using one or more wire drawing dies, that is, the tungsten wire is drawn (thinned) while being heated.
  • the heating temperature is, for example, 1000°C. Note that the higher the heating temperature is, the higher the workability of the tungsten wire is, so that the wire can be easily drawn.
  • the heating wire drawing is performed repeatedly while changing the wire drawing die.
  • the cross-section reduction rate of the tungsten wire by one wire drawing using one wire drawing die is, for example, 10% or more and 40% or less.
  • a lubricant in which graphite is dispersed in water may be used.
  • the heating wire drawing (S18) is repeated until a tungsten wire of the desired wire diameter is obtained (No in S20).
  • the desired wire diameter here is the wire diameter when there are only two wire drawings remaining, and is, for example, about 150 ⁇ m.
  • repeated heating wire drawing a wire drawing die with a smaller hole diameter than the wire drawing die used in the immediately preceding wire drawing is used.
  • the tungsten wire is heated at a lower heating temperature than the heating temperature during the immediately preceding wire drawing. That is, the heating temperature is lowered in stages.
  • the final heating temperature is, for example, 400° C., which contributes to refinement of crystal grains.
  • room temperature drawing is performed (S22). Note that, as shown in FIG. 4, electrolytic polishing may be performed (S21) before room temperature drawing (S22). In room-temperature drawing, the tungsten wire is drawn without heating, thereby achieving further refinement of crystal grains. In addition, drawing at room temperature has the effect of aligning the crystal orientation in the processing axis direction (specifically, in the direction parallel to the wire axis of the tungsten wire 1).
  • the normal temperature is, for example, a temperature in the range of 0°C or more and 50°C or less, and an example is 30°C.
  • a tungsten wire is drawn using a plurality of wire drawing dies having different hole diameters.
  • a water-soluble liquid lubricant is used. Since heating is not performed during room temperature drawing, evaporation of the liquid is suppressed. Therefore, it can function satisfactorily as a liquid lubricant.
  • the tungsten wire is not heated and is processed while being cooled with liquid lubricant, resulting in dynamic recovery and dynamic drawing. It suppresses recrystallization, contributes to the refinement of crystal grains without wire breakage, and can obtain high tensile strength.
  • the processing rate in room temperature wire drawing is, for example, 70% or more.
  • the processing rate is expressed by the following formula (2) using the wire diameter Db immediately before room temperature drawing and the wire diameter Da immediately after room temperature drawing.
  • the larger the wire diameter is reduced by room-temperature drawing the larger the processing rate becomes.
  • the processing rate of drawing at room temperature is 70% or more, but may be 80% or more, 90% or more, or 95% or more.
  • the wire diameter immediately after drawing at room temperature is, for example, approximately in the range of 50 ⁇ m or more and 120 ⁇ m or less.
  • low temperature hot drawing is performed (S24). That is, the final drawing of the tungsten wire is performed while heating at a low temperature.
  • the temperature at this time is higher than the temperature (normal temperature) for room temperature drawing (S22) and lower than the temperature for heating drawing (S18).
  • the temperature of the low-temperature hot drawing ranges from 100°C to 300°C, and is 200°C or 300°C, for example.
  • the wire diameter after low-temperature hot drawing is, for example, approximately in the range of 20 ⁇ m or more and 100 ⁇ m or less.
  • Electrolytic polishing is performed by, for example, immersing the tungsten wire and the counter electrode in an electrolytic solution such as an aqueous sodium hydroxide solution, and creating a potential difference between the tungsten wire and the counter electrode.
  • the tungsten wire 1 is manufactured.
  • the length of the tungsten wire 1 immediately after manufacture is, for example, 50 km or more, and can be used industrially.
  • the tungsten wire 1 can be cut to an appropriate length depending on the mode of use, and can also be used in the form of a needle or rod.
  • each step shown in the method for manufacturing the tungsten wire 1 is performed in-line, for example.
  • the plurality of wire drawing dies used in step S18 are arranged on the production line in order of decreasing hole diameter.
  • a heating device such as a burner is arranged between each wire drawing die.
  • an electropolishing device may be arranged between each wire drawing die.
  • one or more wire drawing dies used in step S22 and one or more wire drawing dies used in step S24 have a smaller hole diameter.
  • the electrolytic polishing device is placed downstream of the wire drawing die with the smallest hole diameter. Note that each step may be performed individually.
  • the method for manufacturing the tungsten wire 1 described above is only an example, and the temperature, wire diameter, etc. in each step can be adjusted as appropriate.
  • tungsten wire 1 As described above, in the method for manufacturing tungsten wire 1 according to the present embodiment, after heating wire drawing is performed at a first temperature that is a high temperature, room temperature drawing is performed at a second temperature that is room temperature. Low temperature hot drawing is performed at a third temperature. The third temperature is higher than the second temperature (normal temperature) and lower than the first temperature (high temperature).
  • the tungsten wire 1 is manufactured by implementing a new process called low-temperature hot drawing (also called low-temperature hot working).
  • low-temperature hot drawing also called low-temperature hot working.
  • FIG. 5 is a diagram showing the relationship between the wire diameter and tensile strength of the tungsten wire 1 containing rhenium or cerium.
  • the horizontal axis represents the wire diameter (unit: ⁇ m) of the tungsten wire 1
  • the vertical axis represents the tensile strength (unit: MPa).
  • the inventors of the present application manufactured a plurality of sample products of the tungsten wire 1 based on the manufacturing method described above.
  • the rhenium content (Re content) was adjusted by adjusting the amount of rhenium powder added to the tungsten powder.
  • the wire diameter was adjusted using wire drawing dies with different hole diameters.
  • the tensile strength is an actual value obtained by measuring the tensile strength of the manufactured tungsten wire 1.
  • the tensile strength was measured, for example, based on the Japanese Industrial Standards tensile test (JIS H 4460 8). Note that by adjusting the heating temperature and/or processing rate in the wire drawing process, it was possible to obtain tungsten wires 1 with the same Re content and different tensile strengths even if the wire diameter was the same.
  • Tables 1 and 2 show specific values for the Re content, wire diameter, and tensile strength of a plurality of sample products of the tungsten wire 1 shown in FIG. 5.
  • Table 1 is a table showing the wire diameter and tensile strength of the tungsten wire 1 containing a predetermined amount of rhenium (Re).
  • Table 2 is a table showing the tensile strength for each Re content of the tungsten wire 1 having a wire diameter of 50 ⁇ m and 30 ⁇ m.
  • the quadratic function on the left side of the inequality in equation (3) is represented by the lower broken line in FIG.
  • the lower broken line in FIG. 5 is obtained by polynomial approximation using a plurality of samples with the smallest tensile strength for each wire diameter among the samples in Table 1.
  • the quadratic function on the right side of the inequality in equation (3) is represented by the upper dashed line in FIG.
  • the upper broken line in FIG. 5 is obtained by translating the above polynomial so that each sample obtained in Tables 1 and 2 falls between the two broken lines.
  • FIG. 5 also shows the relationship between the wire diameter and tensile strength of the tungsten wire 1 containing cerium. Specific numerical values are as shown in Table 3.
  • Table 3 is a table showing the wire diameter and tensile strength of the tungsten wire 1 containing a predetermined amount of cerium (Ce).
  • the tungsten wire 1 containing cerium similarly satisfies the relationship expressed by the above formula (3).
  • cerium is taken as an example here, similar results can be obtained even if other rare earth elements such as lanthanum (La), which have similar characteristics to cerium, are included.
  • La lanthanum
  • FIG. 6 is a diagram showing the relationship between Re content, tensile strength, and circularity for a tungsten wire containing rhenium and having a wire diameter of 50 ⁇ m.
  • Table 4 is a table showing the tensile strength and circularity of a tungsten wire containing a predetermined amount of rhenium and having a wire diameter of 50 ⁇ m.
  • the tungsten wire 1 with a wire diameter of 50 ⁇ m has both a tensile strength of 5200 MPa or more and a circularity of 2.0% or less. Further, when the Re content is in the range of 0.5 wt% or more and 1.0 wt% or less, the tensile strength is 5500 MPa or more and the circularity is 1.0% or less. That is, it is possible to achieve both high tensile strength and improved roundness.
  • FIG. 7 is a diagram showing the relationship between Re content, tensile strength, and circularity for a tungsten wire containing rhenium and having a wire diameter of 30 ⁇ m.
  • Table 5 is a table showing the tensile strength and circularity of a tungsten wire containing a predetermined amount of rhenium and having a wire diameter of 30 ⁇ m.
  • the roundness increases at an almost constant rate from 0.3% to 3.2%.
  • the circularity is 2.0% or less, but when the Re content is 5.0 wt%, the circularity is greater than 2.0%.
  • Ta This tendency is similar to that when the wire diameter is 50 ⁇ m, but as the wire diameter becomes smaller, the tensile strength increases, so the rate of increase in circularity is smaller than when the wire diameter is 50 ⁇ m. It's getting bigger.
  • the tungsten wire 1 with a wire diameter of 30 ⁇ m has both a tensile strength of 5400 MPa or more and a circularity of 2.0% or less. Further, when the Re content is in the range of 0.5 wt% or more and 1.0 wt% or less, the tensile strength is 5750 MPa or more and the roundness is 1.0% or less. That is, it is possible to achieve both high tensile strength and improved roundness.
  • the roundness is better than before when the Re content is in the range of 0.1 wt% or more and 3.0 wt% or less. Furthermore, higher tensile strength can be achieved when the Re content is in the range of 0.1 wt% or more and 3.0 wt% or less. When the Re content is in the range from 0.5 wt% to 1.0 wt%, both higher tensile strength and improved roundness can be achieved. Note that by reducing the wire diameter, the tensile strength can be further increased.
  • FIG. 8 is a diagram showing the relationship between Ce content, tensile strength, and roundness of tungsten wire 1 containing cerium and having a wire diameter of 30 ⁇ m.
  • Table 6 is a table showing the tensile strength and circularity of a tungsten wire containing a predetermined amount of cerium (Ce) and having a wire diameter of 30 ⁇ m.
  • the circularity increases at an almost constant rate from 0.4% to 3.1%.
  • the Ce content is 0.30 wt% or less, the circularity is 2.0% or less, but when the Ce content is 0.50 wt%, the circularity becomes greater than 2.0%.
  • Ta it can be seen that when the Ce content is in the range of 0.03 wt% or more and 0.09 wt% or less, the roundness is 1.0% or less, and the roundness is improved.
  • the tungsten wire 1 contains tungsten as a main component.
  • tensile strength is T (unit: MPa) and wire diameter is D (unit: mm)
  • wire diameter is D (unit: mm)
  • 4758 ⁇ D 2 -7258.3 ⁇ D+5275.5 ⁇ T ⁇ 4758 ⁇ D 2 -7258.3 ⁇ D+6100 satisfy.
  • the circularity of the tungsten wire 1 is 2.0% or less.
  • the tungsten wire 1 may contain rhenium.
  • the content of rhenium in the tungsten wire 1 is 0.1 wt% or more and 3 wt% or less.
  • the tungsten wire 1 may contain a rare earth element.
  • the content of rare earth elements in the tungsten wire 1 is 0.03 wt% or more and 0.3 wt% or less.
  • the content of rare earth elements in the tungsten wire 1 may be 0.03 wt% or more and 0.09 wt% or less.
  • the circularity of the tungsten wire 1 in this case is 1.0% or less.
  • the tensile strength of the tungsten wire 1 is 5800 MPa or more.
  • the tungsten wire 1 when used as a core wire of a saw wire, it is possible to tighten the saw wire strongly, so that shaking of the saw wire when cutting an ingot can be suppressed. By suppressing the swinging of the saw wire, the cutting allowance of the ingot can be made smaller, so that losses can be reduced.
  • the content of tungsten in the tungsten wire 1 may be 97 wt% or more.
  • the wire diameter of the tungsten wire 1 may be 100 ⁇ m or less.
  • the wire diameter is small, when the tungsten wire 1 is used, for example, as a saw wire to slice an ingot, the cutting allowance can be reduced and the number of wafers to be taken can be increased.
  • the tungsten wire 1 is used as a core wire of a saw wire.
  • the tungsten wire 1 may contain two or more elements of rhenium, potassium, and rare earth elements.
  • the tungsten wire 1 may be used for purposes other than the core wire of a saw wire.
  • the tungsten wire 1 may be used as the warp and weft threads of the mesh.
  • a tungsten mesh is manufactured by performing a weaving process using the tungsten wire 1.
  • Tungsten mesh is used in screen printing meshes or cut-resistant clothing.
  • the tungsten wire 1 may be used as a single twisted wire.
  • a stranded wire is manufactured by performing a twisting process using the tungsten wire 1.
  • Stranded wires are used for ropes, catheters, and the like.
  • the tungsten wire 1 may be used for twisting or knitting with organic fibers such as nonwoven fabrics and nylon.
  • a nonwoven fabric may be manufactured by cutting the tungsten wire 1 to a predetermined length or less, and then performing a nonwoven fabric process.
  • the stress applied to the tungsten wire 1 during processing or use tends to be uniform. That is, it is possible to suppress the application of large stress locally to the tungsten wire 1, thereby suppressing the occurrence of wire breakage and the like.

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Abstract

A tungsten wire (1) comprises tungsten as a main component. When the tensile strength of the tungsten wire (1) is T (unit: MPa), and a wire diameter is D (unit: mm), 4758×D2-7258, 3×D+5275.5≤T≤4758×D2-7258.3×D＋6100 is satisfied. A circularity ratio of the tungsten wire (1) is at most 2.0%.

Description

タングステン線tungsten wire
　本発明は、タングステン線に関する。 The present invention relates to tungsten wire.
　特許文献１には、引張強度が４８００ＭＰａ以上のタングステン線が開示されている。 Patent Document 1 discloses a tungsten wire with a tensile strength of 4800 MPa or more.
特開２０２０－１０５５４８号公報JP2020-105548A
　上記従来のタングステン線では、引張強度が高くなること及び添加物の量が多くなると、ダイスを用いた線引き（伸線）の加工性が悪化する。このため、ダイスが摩耗しやすくなって、タングステン線の真円率が悪化する。 In the above-mentioned conventional tungsten wire, when the tensile strength increases and the amount of additives increases, the workability of wire drawing using a die deteriorates. For this reason, the die becomes easily worn, and the roundness of the tungsten wire deteriorates.
　そこで、本発明は、真円率が良化したタングステン線を提供することを目的とする。 Therefore, an object of the present invention is to provide a tungsten wire with improved circularity.
　本発明の一態様に係るタングステン線は、タングステンを主成分として含む。引張強度をＴ（単位：ＭＰａ）とし、線径をＤ（単位：ｍｍ）とした場合に、４７５８×Ｄ２－７２５８．３×Ｄ＋５２７５．５≦Ｔ≦４７５８×Ｄ２－７２５８．３×Ｄ＋６１００を満たす。タングステン線の真円率は、２．０％以下である。 A tungsten wire according to one embodiment of the present invention contains tungsten as a main component. When tensile strength is T (unit: MPa) and wire diameter is D (unit: mm), 4758×D 2 -7258.3×D+5275.5≦T≦4758×D 2 -7258.3×D+6100 satisfy. The roundness of the tungsten wire is 2.0% or less.
　本発明によれば、真円率が良化したタングステン線を実現することができる。 According to the present invention, a tungsten wire with improved circularity can be realized.
図１は、実施の形態に係るタングステン線の外観及び断面を示す模式図である。FIG. 1 is a schematic diagram showing the appearance and cross section of a tungsten wire according to an embodiment. 図２は、真円率を説明するための図である。FIG. 2 is a diagram for explaining roundness. 図３は、実施の形態に係るタングステン線の製造方法の一例を示すフローチャートである。FIG. 3 is a flowchart illustrating an example of a method for manufacturing a tungsten wire according to an embodiment. 図４は、実施の形態に係るタングステン線の製造方法の別の一例を示すフローチャートである。FIG. 4 is a flowchart showing another example of the method for manufacturing a tungsten wire according to the embodiment. 図５は、レニウム又はセリウムを含有するタングステン線の線径と引張強度との関係を示す図である。FIG. 5 is a diagram showing the relationship between the wire diameter and tensile strength of a tungsten wire containing rhenium or cerium. 図６は、レニウムを含有する線径５０μｍのタングステン線について、レニウム含有量と引張強度及び真円率との関係を示す図である。FIG. 6 is a diagram showing the relationship between rhenium content, tensile strength, and circularity for a tungsten wire containing rhenium and having a wire diameter of 50 μm. 図７は、レニウムを含有する線径３０μｍのタングステン線について、レニウム含有量と引張強度及び真円率との関係を示す図である。FIG. 7 is a diagram showing the relationship between rhenium content, tensile strength, and circularity for a tungsten wire containing rhenium and having a wire diameter of 30 μm. 図８は、セリウムを含有する線径３０μｍのタングステン線について、セリウム含有量と引張強度及び真円率との関係を示す図である。FIG. 8 is a diagram showing the relationship between cerium content, tensile strength, and circularity for a tungsten wire containing cerium and having a wire diameter of 30 μm.
　以下では、本発明の実施の形態に係るタングステン線について、図面を用いて詳細に説明する。なお、以下に説明する実施の形態は、いずれも本発明の一具体例を示すものである。したがって、以下の実施の形態で示される数値、形状、材料、構成要素、構成要素の配置及び接続形態、ステップ、ステップの順序などは、一例であり、本発明を限定する趣旨ではない。よって、以下の実施の形態における構成要素のうち、独立請求項に記載されていない構成要素については、任意の構成要素として説明される。 Below, a tungsten wire according to an embodiment of the present invention will be described in detail using the drawings. Note that all of the embodiments described below are specific examples of the present invention. Therefore, the numerical values, shapes, materials, components, arrangement and connection forms of the components, steps, order of steps, etc. shown in the following embodiments are merely examples, and are not intended to limit the present invention. Therefore, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims will be described as arbitrary constituent elements.
　また、各図は、模式図であり、必ずしも厳密に図示されたものではない。したがって、例えば、各図において縮尺などは必ずしも一致しない。また、各図において、実質的に同一の構成については同一の符号を付しており、重複する説明は省略又は簡略化する。 Furthermore, each figure is a schematic diagram and is not necessarily strictly illustrated. Therefore, for example, the scales and the like in each figure do not necessarily match. Further, in each figure, substantially the same configurations are denoted by the same reference numerals, and overlapping explanations will be omitted or simplified.
　また、本明細書において、要素間の関係性を示す用語、要素の形状を示す用語、及び、数値範囲は、厳格な意味のみを表す表現ではなく、実質的に同等な範囲、例えば数％程度の差異をも含むことを意味する表現である。 In addition, in this specification, terms that indicate relationships between elements, terms that indicate the shape of elements, and numerical ranges are not expressions that express only strict meanings, but are substantially equivalent ranges, such as several percentage points. This is an expression that means that it also includes the difference between.
　（実施の形態）
　［タングステン線］
　まず、実施の形態に係るタングステン線について、図１を用いて説明する。図１は、本実施の形態に係るタングステン線１の外観及び断面を示す模式図である。 (Embodiment)
[Tungsten wire]
First, a tungsten wire according to an embodiment will be described using FIG. 1. FIG. 1 is a schematic diagram showing the appearance and cross section of a tungsten wire 1 according to the present embodiment.
　図１に示されるように、タングステン線１は、巻枠２に巻回されて保管される。巻枠２は、ボビン、リール、スプール又はドラムなどと称される場合がある。タングステン線１は、例えば、５０ｋｍ以上３００ｋｍ以下といったｋｍオーダーの全長を有する。 As shown in FIG. 1, the tungsten wire 1 is wound around a winding frame 2 and stored. The winding frame 2 is sometimes referred to as a bobbin, reel, spool, or drum. The tungsten wire 1 has a total length on the order of km, for example, 50 km or more and 300 km or less.
　図１に示されるタングステン線１は、タングステン製品の製造に利用される。例えば、タングステン線１は、ソーワイヤの芯線として用いられる。具体的には、ソーワイヤは、固定砥粒方式のワイヤであり、タングステン線１を芯線として備え、さらに、ダイヤモンド粒子又は立方晶窒化ホウ素（ＣＢＮ）粒子などの砥粒を備える。砥粒は、タングステン線１の表面に固着される。固着は、電着でもよく、レジンボンドによる固着でもよい。また、ソーワイヤは、遊離砥粒方式のワイヤであってもよい。例えば、ソーワイヤは、砥粒を備えずにタングステン線１そのものであってもよい。 The tungsten wire 1 shown in FIG. 1 is used for manufacturing tungsten products. For example, the tungsten wire 1 is used as a core wire of a saw wire. Specifically, the saw wire is a wire of a fixed abrasive type, and includes a tungsten wire 1 as a core wire, and further includes abrasive grains such as diamond particles or cubic boron nitride (CBN) particles. The abrasive grains are fixed to the surface of the tungsten wire 1. The fixing may be by electrodeposition or by resin bonding. Further, the saw wire may be a loose abrasive type wire. For example, the saw wire may be the tungsten wire 1 itself without any abrasive grains.
　ソーワイヤは、例えば、シリコン（Ｓｉ）又はシリコンカーバイド（ＳｉＣ）などの半導体インゴットの切断に利用される。ソーワイヤによって半導体インゴットをスライスすることにより、半導体ウェハを製造することができる。このとき、ソーワイヤの線径が小さい程、切り代が小さくなるので、ロスが減り、ウェハの取り数を増やすことができる。なお、切断対象物は、半導体インゴットに限定されず、ガラス、コンクリート、水晶又はセラミックスなどであってもよい。 Saw wires are used, for example, to cut semiconductor ingots such as silicon (Si) or silicon carbide (SiC). Semiconductor wafers can be manufactured by slicing a semiconductor ingot with a saw wire. At this time, the smaller the wire diameter of the saw wire, the smaller the cutting allowance, which reduces loss and increases the number of wafers to be taken. Note that the object to be cut is not limited to a semiconductor ingot, and may be glass, concrete, crystal, ceramics, or the like.
　タングステン線１は、タングステン（Ｗ）を主成分として含む。「主成分」とは、元素の含有量（含有率）が５０ｗｔ％より多いことを意味する。例えば、タングステン線１に含まれるタングステンの含有量は、９７ｗｔ％以上である。タングステン線１に含まれるタングステンの含有量は、９９ｗｔ％以上であってもよく、９９．９ｗｔ％以上であってもよく、９９．９９ｗｔ％以上であってもよい。タングステン線１は、後述する添加物以外に、製造過程において混入が避けられない不可避的不純物が含まれていてもよい。 The tungsten wire 1 contains tungsten (W) as a main component. "Main component" means that the content (content rate) of the element is more than 50 wt%. For example, the content of tungsten contained in the tungsten wire 1 is 97 wt% or more. The content of tungsten contained in the tungsten wire 1 may be 99 wt% or more, 99.9 wt% or more, or 99.99 wt% or more. In addition to the additives described below, the tungsten wire 1 may also contain unavoidable impurities that are unavoidably mixed in during the manufacturing process.
　タングステン線１は、例えば、レニウム（Ｒｅ）を含む。タングステン線１におけるレニウムの含有量は、例えば０．１ｗｔ％以上３ｗｔ％以下である。レニウムは、タングステンと合金（固溶体）を構成する。 The tungsten wire 1 contains, for example, rhenium (Re). The content of rhenium in the tungsten wire 1 is, for example, 0.1 wt% or more and 3 wt% or less. Rhenium constitutes an alloy (solid solution) with tungsten.
　レニウムの含有量が多い場合、タングステン線１の引張強度を高めることができる。一方で、レニウムの含有量が多すぎる場合には、タングステン線１の引張強度を高く維持したまま、細線化を行うことが難しい。具体的には、断線が発生しやすくなり、長尺での線引きが難しくなる。レニウムの含有量を少なくし、タングステンの含有量を９７ｗｔ％以上にすることにより、タングステン線１の加工性を高めることができる。また、希少で高価なレニウムの含有量を少なくすることで、安価なタングステン線１を長尺で大量生産が可能になる。 When the rhenium content is high, the tensile strength of the tungsten wire 1 can be increased. On the other hand, if the rhenium content is too high, it is difficult to thin the tungsten wire 1 while maintaining its high tensile strength. Specifically, wire breaks are more likely to occur, making it difficult to draw long wires. By reducing the rhenium content and increasing the tungsten content to 97 wt% or more, the workability of the tungsten wire 1 can be improved. Furthermore, by reducing the content of rare and expensive rhenium, it becomes possible to mass produce long, inexpensive tungsten wires 1.
　なお、タングステンとの合金に用いられる金属は、オスミウム（Ｏｓ）、ルテニウム（Ｒｕ）又はイリジウム（Ｉｒ）であってもよい。オスミウム、ルテニウム又はイリジウムの含有量は、例えばレニウムの含有量と同様である。これらの場合もレニウムタングステン合金の場合と同様の効果が得られる。また、タングステン線１は、タングステンと、タングステン以外の２種類以上の金属との合金からなってもよい。 Note that the metal used for the alloy with tungsten may be osmium (Os), ruthenium (Ru), or iridium (Ir). The content of osmium, ruthenium or iridium is similar to the content of rhenium, for example. In these cases, the same effects as in the case of rhenium-tungsten alloy can be obtained. Further, the tungsten wire 1 may be made of an alloy of tungsten and two or more metals other than tungsten.
　タングステン線１は、カリウム（Ｋ）を含んでもよい。タングステン線１におけるカリウムの含有量は、例えば０．００１ｗｔ％以上０．０１ｗｔ％以下である。カリウムは、タングステンの結晶粒界に存在する。カリウムを含むタングステン線１でも、ピアノ線の一般的な引張強度よりも高い引張強度を実現することができる。 The tungsten wire 1 may contain potassium (K). The potassium content in the tungsten wire 1 is, for example, 0.001 wt% or more and 0.01 wt% or less. Potassium exists at the grain boundaries of tungsten. Even the tungsten wire 1 containing potassium can achieve a tensile strength higher than the general tensile strength of piano wire.
　また、タングステン線１は、希土類元素を含んでもよい。タングステン線１における希土類元素の含有量は、例えば０．０３ｗｔ％以上０．３ｗｔ％以下である。タングステン線１における希土類元素の含有量は、例えば０．０３ｗｔ％以上０．０９ｗｔ％以下であってもよい。希土類元素は、例えばセリウム（Ｃｅ）、ランタン（Ｌａ）、イットリウム（Ｙ）又はサマリウム（Ｓｍ）などである。希土類元素は、タングステンの結晶粒界に存在する。希土類元素を含むタングステン線１でも、ピアノ線の一般的な引張強度よりも高い引張強度を実現することができる。 Additionally, the tungsten wire 1 may contain a rare earth element. The content of rare earth elements in the tungsten wire 1 is, for example, 0.03 wt% or more and 0.3 wt% or less. The content of rare earth elements in the tungsten wire 1 may be, for example, 0.03 wt% or more and 0.09 wt% or less. Examples of rare earth elements include cerium (Ce), lanthanum (La), yttrium (Y), and samarium (Sm). Rare earth elements are present at the grain boundaries of tungsten. Even the tungsten wire 1 containing rare earth elements can achieve a tensile strength higher than the general tensile strength of piano wire.
　一例として、タングステン線１の線径は、１００μｍ以下である。タングステン線１の線径が小さくなる程、ソーワイヤの芯線として用いられた場合に、切断物のロスを減らすことができる。タングステン線１の線径は、８０μｍ以下であってもよく、７０μｍ以下であってもよく、６０μｍ以下であってもよく、５０μｍ以下であってもよく、４０μｍ以下であってもよく、３０μｍ以下であってもよく、２０μｍ以下であってもよく、１５μｍ以下であってもよい。また、後述する製造方法によれば、１３μｍ以下の極めて細い線径のタングステン線１も実現される。タングステン線１の線径は、１０μｍ以下であってもよく、８μｍ以下であってもよく、７μｍ以下であってもよい。タングステン線１の線径は、例えば５μｍ以上であるが、これに限定されない。 As an example, the wire diameter of the tungsten wire 1 is 100 μm or less. The smaller the wire diameter of the tungsten wire 1 is, the more the loss of cut material can be reduced when it is used as a core wire of a saw wire. The wire diameter of the tungsten wire 1 may be 80 μm or less, 70 μm or less, 60 μm or less, 50 μm or less, 40 μm or less, 30 μm or less It may be 20 μm or less, or 15 μm or less. Further, according to the manufacturing method described later, a tungsten wire 1 having an extremely thin wire diameter of 13 μm or less can also be realized. The wire diameter of the tungsten wire 1 may be 10 μm or less, 8 μm or less, or 7 μm or less. The wire diameter of the tungsten wire 1 is, for example, 5 μm or more, but is not limited thereto.
　また、一例として、タングステン線１の引張強度は、４８００ＭＰａ以上である。引張強度は、４９００ＭＰａ以上であってもよく、５０００ＭＰａ以上であってもよく、５２００ＭＰａ以上であってもよく、５５００ＭＰａ以上であってもよい。また、５８００ＭＰａ以上の極めて高い引張強度のタングステン線１も実現される。タングステン線１の引張強度は、５９００ＭＰａ以上であってもよく、６０００ＭＰａ以上であってもよい。引張強度は、例えば、日本工業規格の引張試験（ＪＩＳ　Ｈ　４４６０　８）に基づいて測定可能である。 Further, as an example, the tensile strength of the tungsten wire 1 is 4800 MPa or more. The tensile strength may be 4900 MPa or more, 5000 MPa or more, 5200 MPa or more, or 5500 MPa or more. Moreover, a tungsten wire 1 having an extremely high tensile strength of 5800 MPa or more is also realized. The tensile strength of the tungsten wire 1 may be 5900 MPa or more, or 6000 MPa or more. The tensile strength can be measured, for example, based on the Japanese Industrial Standards tensile test (JIS H 4460 8).
　本実施の形態に係るタングステン線１は、引張強度をＴ（単位：ＭＰａ）とし、線径をＤ（単位：ｍｍ）とした場合に、所定の関係を満たす。具体的には、線径に応じた引張強度が従来よりも高いタングステン線１が実現されている。引張強度Ｔと線径Ｄとの具体的な関係については、具体的な実施例とともに図５を用いて後で説明する。 The tungsten wire 1 according to the present embodiment satisfies a predetermined relationship where the tensile strength is T (unit: MPa) and the wire diameter is D (unit: mm). Specifically, the tungsten wire 1 has been realized which has higher tensile strength than the conventional wire depending on the wire diameter. The specific relationship between the tensile strength T and the wire diameter D will be explained later using FIG. 5 along with specific examples.
　本実施の形態では、タングステン線１の真円率は、２．０％以下である。すなわち、タングステン線１の断面（線軸方向に直交する断面）の形状は、十分に真円に近い形状を有する。なお、図１では、タングステン線１の断面と真円との差を誇張して図示している。 In this embodiment, the circularity of the tungsten wire 1 is 2.0% or less. That is, the shape of the cross section of the tungsten wire 1 (the cross section perpendicular to the wire axis direction) has a shape sufficiently close to a perfect circle. In addition, in FIG. 1, the difference between the cross section of the tungsten wire 1 and the perfect circle is exaggerated.
　ここで、真円率について、図２を用いて説明する。図２は、真円率を説明するための図である。真円率とは、タングステン線１の断面形状の、真円からのずれの大きさを表す指標である。真円率が小さい程、ずれが小さい、すなわち、タングステン線１の断面形状が真円に近いことを意味する。真円率が大きい程、ずれが大きい、すなわち、タングステン線１の断面形状が真円から遠ざかることを意味する。 Here, circularity will be explained using FIG. 2. FIG. 2 is a diagram for explaining roundness. The circularity is an index representing the size of deviation of the cross-sectional shape of the tungsten wire 1 from a perfect circle. The smaller the circularity, the smaller the deviation, which means that the cross-sectional shape of the tungsten wire 1 is closer to a perfect circle. The larger the circularity, the larger the deviation, that is, the farther the cross-sectional shape of the tungsten wire 1 is from a perfect circle.
　具体的には、真円率ｆ（単位：％）は、以下の式（１）で表される。 Specifically, the circularity f (unit: %) is expressed by the following formula (1).
　（１）　ｆ＝（Ａ－Ｂ）／（（Ａ＋Ｂ）／２）×１００ (1) f=(AB)/((A+B)/2)×100
　Ａ及びＢは、図２に示されるとおりである。具体的にはまず、タングステン線１の断面に対して、最大内接円と最小外接円とを定義する。最大内接円と最小外接円とは、同心円となり、かつ、互いの間隔が最小になるように定義される。すなわち、最小外接円の半径をｒ（Ａ）、最大内接円の半径をｒ（Ｂ）とすると、ｒ（Ａ）－ｒ（Ｂ）が最小となる。 A and B are as shown in FIG. 2. Specifically, first, a maximum inscribed circle and a minimum circumscribed circle are defined for the cross section of the tungsten wire 1. The maximum inscribed circle and the minimum circumscribed circle are defined to be concentric circles and to minimize the distance between them. That is, if the radius of the minimum circumscribed circle is r(A) and the radius of the maximum inscribed circle is r(B), then r(A)-r(B) is the minimum.
　この場合において、Ａは、最小外接円の直径であり、２×ｒ（Ａ）で表される。Ｂは、最大内接円の直径であり、２×ｒ（Ｂ）で表される。真円率ｆは、上記式（１）に示されるとおり、最小外接円の直径と最大内接円の直径との平均値に対する、最小外接円の直径と最大内接円の直径との差の比を百分率で表したものである。ｆ＝０であれば、最小外接円と最大内接円とが一致することになるので、タングステン線１の断面が真円となる。 In this case, A is the diameter of the minimum circumscribed circle and is expressed as 2×r(A). B is the diameter of the maximum inscribed circle and is expressed as 2×r(B). As shown in the above formula (1), the circularity f is the difference between the diameter of the minimum circumscribed circle and the diameter of the maximum inscribed circle with respect to the average value of the diameter of the minimum circumscribed circle and the diameter of the maximum inscribed circle. The ratio is expressed as a percentage. If f=0, the minimum circumscribed circle and the maximum inscribed circle match, so the cross section of the tungsten wire 1 becomes a perfect circle.
　本実施の形態によれば、線径に応じた引張強度が従来よりも高く、かつ、真円率が良化した（すなわち、断面が真円に近い）タングステン線１を実現することができる。例えば、タングステン線１がソーワイヤの芯線として利用される場合、真円率が良化することで、スライス物（ウェハ）の厚みのばらつきを抑制することができる。特に、真円率が２％又は３％を超えると、ウェハの厚みのばらつきであるＴＴＶ（Ｔｏｔａｌ　Ｔｈｉｃｋｎｅｓｓ　Ｖａｒｉａｔｉｏｎ）は、急激に悪化する。 According to the present embodiment, it is possible to realize a tungsten wire 1 that has higher tensile strength depending on the wire diameter than conventional wires and has improved roundness (that is, the cross section is close to a perfect circle). For example, when the tungsten wire 1 is used as a core wire of a saw wire, the roundness is improved, and variations in the thickness of sliced objects (wafers) can be suppressed. In particular, when the circularity exceeds 2% or 3%, TTV (Total Thickness Variation), which is the variation in wafer thickness, deteriorates rapidly.
　［製造方法］
　続いて、本実施の形態に係るタングステン線１の製造方法について、図３及び図４を用いて説明する。図３及び図４はそれぞれ、本実施の形態に係るタングステン線１の製造方法の一例を示すフローチャートである。 [Production method]
Next, a method for manufacturing the tungsten wire 1 according to the present embodiment will be described using FIGS. 3 and 4. 3 and 4 are flowcharts each showing an example of the method for manufacturing the tungsten wire 1 according to the present embodiment.
　図３に示されるように、まず、タングステンに添加物を加える（Ｓ１０）。例えば、所定量のタングステン粉末に対して、添加物（ドープ元素）のみ、又は、添加物を含む化合物（例えば、酸化物又は水溶液）を添加する。ドープ元素は、レニウム、カリウム、又は、セリウム若しくはランタンなどの希土類元素である。化合物に含まれる不要な成分は、その後の焼結などにより除去される。得られたドープタングステン粉末に対して、タングステン粉末を所定の割合で加えることによって、ドープ元素の添加量を調整する。すなわち、目的とするドープ元素の含有量よりも多い量でドープ元素を添加してもよい。 As shown in FIG. 3, first, additives are added to tungsten (S10). For example, only an additive (doping element) or a compound containing the additive (for example, an oxide or an aqueous solution) is added to a predetermined amount of tungsten powder. The doping element is rhenium, potassium, or a rare earth element such as cerium or lanthanum. Unnecessary components contained in the compound are removed by subsequent sintering or the like. The amount of doping element added is adjusted by adding tungsten powder at a predetermined ratio to the obtained doped tungsten powder. That is, the doping element may be added in an amount greater than the intended content of the doping element.
　このように、少量のタングステン粉末に対してドープ元素の添加を行った後、タングステン粉末を加えてドープ元素を薄める（含有量を少なくする）ことができる。すなわち、ドープ元素の添加工程では、処理対象量が少なくて済むので、小型の添加装置を利用することができる。また、１回の添加工程で多くのドープタングステン粉末を得ることができるので、添加工程の必要工数を減らすことができる。これにより、タングステン線１の生産性を高めることができる。 In this way, after the dope element is added to a small amount of tungsten powder, the tungsten powder can be added to dilute the dope element (reduce the content). That is, in the doping element addition step, the amount to be treated can be small, so a small addition device can be used. Furthermore, since a large amount of doped tungsten powder can be obtained in one addition process, the number of steps required for the addition process can be reduced. Thereby, productivity of the tungsten wire 1 can be improved.
　次に、得られたドープタングステン粉末の集合物に対してプレス及び焼結（シンター）を行うことで、タングステンインゴットを作製する（Ｓ１２）。 Next, a tungsten ingot is produced by pressing and sintering the obtained doped tungsten powder aggregate (S12).
　次に、作製したタングステンインゴットに対してスエージング加工を行う（Ｓ１４）。具体的には、タングステンインゴットを周囲から鍛造圧縮して伸展させることで、ワイヤ状のタングステン線に成形する。スエージング加工の代わりに圧延加工が行われてもよい。 Next, a swaging process is performed on the produced tungsten ingot (S14). Specifically, a tungsten ingot is forged and compressed from its periphery and expanded to form a wire-like tungsten wire. Rolling may be performed instead of swaging.
　例えば、スエージング加工を繰り返し行うことで、直径が約１５ｍｍ以上約２５ｍｍ以下のタングステンインゴットを、線径が約３ｍｍ以上４ｍｍ以下のタングステン線に成形する。スエージング加工の途中の工程においてアニール処理を実施することにより、以降の処理における加工性を確保する。例えば、直径が８ｍｍ以上１０ｍｍ以下の範囲で、２０００℃以上２４００℃以下のアニール処理を実施する。ただし、結晶粒微細化による引張強度の確保のため、直径が８ｍｍ未満のスエージング工程では、アニール処理を実施しない。 For example, by repeatedly performing swaging processing, a tungsten ingot with a diameter of about 15 mm or more and about 25 mm or less is formed into a tungsten wire with a wire diameter of about 3 mm or more and 4 mm or less. By performing annealing treatment in the middle of the swaging process, workability in subsequent processes is ensured. For example, the annealing treatment is performed at 2000° C. or more and 2400° C. or less in a diameter range of 8 mm or more and 10 mm or less. However, in order to ensure tensile strength through grain refinement, annealing is not performed in the swaging process for diameters of less than 8 mm.
　次に、加熱線引きを行う前にタングステン線を９００℃で加熱する（Ｓ１６）。具体的には、バーナーなどで直接的にタングステン線を加熱する。タングステン線を加熱することで、以降の加熱線引きで加工中に断線しないようにタングステン線の表面に酸化物層を形成する。 Next, the tungsten wire is heated at 900° C. before heating wire drawing (S16). Specifically, the tungsten wire is directly heated with a burner or the like. By heating the tungsten wire, an oxide layer is formed on the surface of the tungsten wire to prevent the wire from breaking during subsequent heating wire drawing.
　次に、加熱線引きを行う（Ｓ１８）。具体的には、１つ以上の伸線ダイスを用いてタングステン線の線引き、すなわち、タングステン線の伸線（細線化）を加熱しながら行う。加熱温度は、例えば１０００℃である。なお、加熱温度が高い程、タングステン線の加工性が高められるので、容易に線引きを行うことができる。加熱線引きは、伸線ダイスを交換しながら繰り返し行われる。１つの伸線ダイスを用いた１回の線引きによるタングステン線の断面減少率は、例えば１０％以上４０％以下である。加熱線引き工程において、黒鉛を水に分散させた潤滑剤を用いてもよい。 Next, heating wire drawing is performed (S18). Specifically, the tungsten wire is drawn using one or more wire drawing dies, that is, the tungsten wire is drawn (thinned) while being heated. The heating temperature is, for example, 1000°C. Note that the higher the heating temperature is, the higher the workability of the tungsten wire is, so that the wire can be easily drawn. The heating wire drawing is performed repeatedly while changing the wire drawing die. The cross-section reduction rate of the tungsten wire by one wire drawing using one wire drawing die is, for example, 10% or more and 40% or less. In the heating wire drawing process, a lubricant in which graphite is dispersed in water may be used.
　所望の線径のタングステン線が得られるまで（Ｓ２０でＮｏ）、加熱線引き（Ｓ１８）が繰り返される。ここでの所望の線径は、線引き回数が残り２回になるときの線径であり、例えば、１５０μｍ程度である。 The heating wire drawing (S18) is repeated until a tungsten wire of the desired wire diameter is obtained (No in S20). The desired wire diameter here is the wire diameter when there are only two wire drawings remaining, and is, for example, about 150 μm.
　なお、加熱線引きの繰り返しにおいては、直前の線引きで用いた伸線ダイスよりも孔径が小さい伸線ダイスが用いられる。また、加熱線引きの繰り返しにおいて、直前の線引き時の加熱温度よりも低い加熱温度でタングステン線は加熱される。つまり、加熱温度は、段階的に低くなる。最後の加熱温度は、例えば４００℃であり、結晶粒の微細化に寄与させる。 Note that in repeated heating wire drawing, a wire drawing die with a smaller hole diameter than the wire drawing die used in the immediately preceding wire drawing is used. In addition, during repeated heating wire drawing, the tungsten wire is heated at a lower heating temperature than the heating temperature during the immediately preceding wire drawing. That is, the heating temperature is lowered in stages. The final heating temperature is, for example, 400° C., which contributes to refinement of crystal grains.
　所望の線径のタングステン線が得られ、残りの線引き回数が２回である場合（Ｓ２０でＹｅｓ）、常温線引きを行う（Ｓ２２）。なお、図４に示されるように、常温線引き（Ｓ２２）の前に電解研磨を行ってもよい（Ｓ２１）。常温線引きでは、加熱をせずにタングステン線の線引きを行うことで、さらなる結晶粒の微細化を実現する。また、常温線引きにより結晶方位を加工軸方向（具体的には、タングステン線１の線軸に平行な方向）に揃える効果もある。 If a tungsten wire with the desired wire diameter is obtained and the remaining number of wire drawings is two (Yes in S20), room temperature drawing is performed (S22). Note that, as shown in FIG. 4, electrolytic polishing may be performed (S21) before room temperature drawing (S22). In room-temperature drawing, the tungsten wire is drawn without heating, thereby achieving further refinement of crystal grains. In addition, drawing at room temperature has the effect of aligning the crystal orientation in the processing axis direction (specifically, in the direction parallel to the wire axis of the tungsten wire 1).
　常温とは、例えば０℃以上５０℃以下の範囲の温度であり、一例として３０℃である。具体的には、孔径が異なる複数の伸線ダイスを用いてタングステン線の線引きを行う。常温線引きでは、水溶性などの液体潤滑剤を用いる。常温線引きでは加熱を行わないため、液体の蒸発が抑制される。したがって、液体潤滑剤として十分な機能を発揮させることができる。従来の伝統的なタングステン線の加工方法である６００℃以上の加熱線引きに対し、タングステン線への加熱を行わず、また、液体潤滑剤で冷却しながら加工することで、動的回復及び動的再結晶を抑制し、断線することなく、結晶粒の微細化に寄与させ、高い引張強度を得ることができる。 The normal temperature is, for example, a temperature in the range of 0°C or more and 50°C or less, and an example is 30°C. Specifically, a tungsten wire is drawn using a plurality of wire drawing dies having different hole diameters. In room temperature drawing, a water-soluble liquid lubricant is used. Since heating is not performed during room temperature drawing, evaporation of the liquid is suppressed. Therefore, it can function satisfactorily as a liquid lubricant. Unlike the conventional traditional tungsten wire processing method, which is heated wire drawing at 600°C or higher, the tungsten wire is not heated and is processed while being cooled with liquid lubricant, resulting in dynamic recovery and dynamic drawing. It suppresses recrystallization, contributes to the refinement of crystal grains without wire breakage, and can obtain high tensile strength.
　常温線引きでの加工率は、例えば７０％以上である。加工率は、常温線引き直前の線径Ｄｂと常温線引き直後の線径Ｄａとを用いて、以下の式（２）で表される。 The processing rate in room temperature wire drawing is, for example, 70% or more. The processing rate is expressed by the following formula (2) using the wire diameter Db immediately before room temperature drawing and the wire diameter Da immediately after room temperature drawing.
　（２）　加工率＝｛１－（Ｄａ／Ｄｂ）２｝×１００ (2) Processing rate = {1-(Da/Db) 2 }×100
　式（２）から分かるように、常温線引きによって線径が大きく減る程、その加工率が大きな値になる。例えば、常温線引き直前の線径Ｄｂが同じであっても、加工率が大きい程、常温線引き直後の線径Ｄａが小さくなる。加工率を大きくすることで、常温線引きによるタングステン線の細線化の程度が大きくなる、つまり、より細いタングステン線が得られる。常温線引きの加工率は、７０％以上であるが、８０％以上であってもよく、９０％以上であってもよく、９５％以上であってもよい。常温線引き直後の線径は、例えば、おおよそ５０μｍ以上１２０μｍ以下の範囲である。 As can be seen from equation (2), the larger the wire diameter is reduced by room-temperature drawing, the larger the processing rate becomes. For example, even if the wire diameter Db immediately before drawing at room temperature is the same, the larger the processing rate is, the smaller the diameter Da immediately after drawing at room temperature becomes. By increasing the processing rate, the degree of thinning of the tungsten wire by drawing at room temperature increases, that is, a thinner tungsten wire can be obtained. The processing rate of drawing at room temperature is 70% or more, but may be 80% or more, 90% or more, or 95% or more. The wire diameter immediately after drawing at room temperature is, for example, approximately in the range of 50 μm or more and 120 μm or less.
　次に、常温線引きの後、低温熱間線引きを行う（Ｓ２４）。つまり、低温で加熱しながら、タングステン線の最後の線引きを行う。このときの温度は、常温線引き（Ｓ２２）の温度（常温）よりも高く、加熱線引き（Ｓ１８）の温度よりも低い温度である。具体的には、低温熱間線引きの温度は、１００℃以上３００℃以下の範囲であり、一例として２００℃又は３００℃である。低温熱間線引き後の線径は、例えば、おおよそ２０μｍ以上１００μｍ以下の範囲である。 Next, after room temperature drawing, low temperature hot drawing is performed (S24). That is, the final drawing of the tungsten wire is performed while heating at a low temperature. The temperature at this time is higher than the temperature (normal temperature) for room temperature drawing (S22) and lower than the temperature for heating drawing (S18). Specifically, the temperature of the low-temperature hot drawing ranges from 100°C to 300°C, and is 200°C or 300°C, for example. The wire diameter after low-temperature hot drawing is, for example, approximately in the range of 20 μm or more and 100 μm or less.
　最後に、低温熱間線引きを行うことで形成されたタングステン線に対して、直径を微調整するために、電解研磨を行う（Ｓ２６）。電解研磨は、例えば、水酸化ナトリウム水溶液などの電解液に、タングステン線と対向電極とを浸した状態で、タングステン線と対向電極との間に電位差が生じることで電解研磨が行われる。 Finally, electropolishing is performed on the tungsten wire formed by low-temperature hot drawing in order to finely adjust the diameter (S26). Electrolytic polishing is performed by, for example, immersing the tungsten wire and the counter electrode in an electrolytic solution such as an aqueous sodium hydroxide solution, and creating a potential difference between the tungsten wire and the counter electrode.
　以上の工程を経て、本実施の形態に係るタングステン線１が製造される。以上の工程を経ることで製造直後のタングステン線１の長さは、例えば５０ｋｍ以上の長さであり工業的に利用できる。タングステン線１は、使用される態様に応じて適切な長さに切断され、針又は棒の形状として使用することもできる。 Through the above steps, the tungsten wire 1 according to the present embodiment is manufactured. By going through the above steps, the length of the tungsten wire 1 immediately after manufacture is, for example, 50 km or more, and can be used industrially. The tungsten wire 1 can be cut to an appropriate length depending on the mode of use, and can also be used in the form of a needle or rod.
　なお、タングステン線１の製造方法に示される各工程は、例えばインラインで行われる。具体的には、ステップＳ１８で使用される複数の伸線ダイスは、生産ライン上で孔径が小さくなる順で配置される。また、各伸線ダイス間にはバーナーなどの加熱装置が配置されている。また、各伸線ダイス間には電解研磨装置が配置されていてもよい。ステップＳ１８で使用される伸線ダイスの下流側（後工程側）に、ステップＳ２２で使用される１以上の伸線ダイス及びステップＳ２４で使用される１以上の伸線ダイスが、孔径が小さくなる順で配置され、最も孔径が小さい伸線ダイスの下流側に電解研磨装置が配置される。なお、各工程は、個別に行われてもよい。 Note that each step shown in the method for manufacturing the tungsten wire 1 is performed in-line, for example. Specifically, the plurality of wire drawing dies used in step S18 are arranged on the production line in order of decreasing hole diameter. Further, a heating device such as a burner is arranged between each wire drawing die. Moreover, an electropolishing device may be arranged between each wire drawing die. On the downstream side (post-process side) of the wire drawing die used in step S18, one or more wire drawing dies used in step S22 and one or more wire drawing dies used in step S24 have a smaller hole diameter. The electrolytic polishing device is placed downstream of the wire drawing die with the smallest hole diameter. Note that each step may be performed individually.
　また、上述したタングステン線１の製造方法は一例に過ぎず、各工程における温度及び線径などは、適宜調整可能である。 Further, the method for manufacturing the tungsten wire 1 described above is only an example, and the temperature, wire diameter, etc. in each step can be adjusted as appropriate.
　以上のように、本実施の形態に係るタングステン線１の製造方法では、高温である第１の温度で加熱線引きを行った後、常温である第２の温度で常温線引きを行い、その後、低温である第３の温度で低温熱間線引きを行う。第３の温度は、第２の温度（常温）より高く、第１の温度（高温）より低い。 As described above, in the method for manufacturing tungsten wire 1 according to the present embodiment, after heating wire drawing is performed at a first temperature that is a high temperature, room temperature drawing is performed at a second temperature that is room temperature. Low temperature hot drawing is performed at a third temperature. The third temperature is higher than the second temperature (normal temperature) and lower than the first temperature (high temperature).
　このように、タングステン線１は、低温熱間線引き（低温熱間加工とも呼ばれる）という新たな工程を実施することによって製造される。低温熱間線引きが行われることによって、線径が小さくて、引張強度が高く、真円率が良化したタングステン線１が実現される。 In this way, the tungsten wire 1 is manufactured by implementing a new process called low-temperature hot drawing (also called low-temperature hot working). By performing the low-temperature hot drawing, a tungsten wire 1 having a small wire diameter, high tensile strength, and improved circularity is realized.
　［引張強度と線径との関係］
　続いて、本実施の形態に係るタングステン線１の引張強度と線径との関係について、図５を用いて説明する。 [Relationship between tensile strength and wire diameter]
Next, the relationship between the tensile strength and wire diameter of the tungsten wire 1 according to the present embodiment will be explained using FIG. 5.
　図５は、レニウム又はセリウムを含有するタングステン線１の線径と引張強度との関係を示す図である。図５では、横軸がタングステン線１の線径（単位：μｍ）を表し、縦軸が引張強度（単位：ＭＰａ）を表している。 FIG. 5 is a diagram showing the relationship between the wire diameter and tensile strength of the tungsten wire 1 containing rhenium or cerium. In FIG. 5, the horizontal axis represents the wire diameter (unit: μm) of the tungsten wire 1, and the vertical axis represents the tensile strength (unit: MPa).
　本願発明者らは、上述した製造方法に基づいて、タングステン線１のサンプル品を複数製造した。レニウムの含有量（Ｒｅ含有量）は、タングステン粉末に添加するレニウム粉末の量を調整することで調整した。線径は、孔径の異なる伸線ダイスを用いて調整した。引張強度は、製造されたタングステン線１の引張強度を測定することで得られた実測値である。引張強度の測定は、例えば、日本工業規格の引張試験（ＪＩＳ　Ｈ　４４６０　８）に基づいて行った。なお、伸線工程における加熱温度及び／又は加工率を調整することで、同じＲｅ含有量で、かつ、同じ線径であっても異なる引張強度のタングステン線１を得ることができた。 The inventors of the present application manufactured a plurality of sample products of the tungsten wire 1 based on the manufacturing method described above. The rhenium content (Re content) was adjusted by adjusting the amount of rhenium powder added to the tungsten powder. The wire diameter was adjusted using wire drawing dies with different hole diameters. The tensile strength is an actual value obtained by measuring the tensile strength of the manufactured tungsten wire 1. The tensile strength was measured, for example, based on the Japanese Industrial Standards tensile test (JIS H 4460 8). Note that by adjusting the heating temperature and/or processing rate in the wire drawing process, it was possible to obtain tungsten wires 1 with the same Re content and different tensile strengths even if the wire diameter was the same.
　図５に示したタングステン線１の複数のサンプル品のＲｅ含有量、線径及び引張強度の具体的な数値を表１及び表２に示す。 Tables 1 and 2 show specific values for the Re content, wire diameter, and tensile strength of a plurality of sample products of the tungsten wire 1 shown in FIG. 5.
　表１は、レニウム（Ｒｅ）を所定量含むタングステン線１の線径と引張強度とを示す表である。 Table 1 is a table showing the wire diameter and tensile strength of the tungsten wire 1 containing a predetermined amount of rhenium (Re).
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表２は、線径が５０μｍ及び３０μｍのタングステン線１のＲｅ含有量毎の引張強度を示す表である。 Table 2 is a table showing the tensile strength for each Re content of the tungsten wire 1 having a wire diameter of 50 μm and 30 μm.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　図５に示されるように、線径と引張強度とには負の相関関係が存在する。つまり、線径が小さい程、引張強度が高くなり、線径が大きい程、引張強度が低くなる。 As shown in FIG. 5, there is a negative correlation between wire diameter and tensile strength. That is, the smaller the wire diameter, the higher the tensile strength, and the larger the wire diameter, the lower the tensile strength.
　本実施の形態に係るタングステン線１では、線径をＤ［ｍｍ］とした場合、以下の式（３）の範囲が満たされる。 In the tungsten wire 1 according to the present embodiment, when the wire diameter is D [mm], the following range of formula (3) is satisfied.
　（３）　４７５８×Ｄ２－７２５８．３×Ｄ＋５２７５．５≦Ｔ≦４７５８×Ｄ２－７２５８．３×Ｄ＋６１００ (3) 4758×D 2 −7258.3×D+5275.5≦T≦4758×D 2 −7258.3×D+6100
　式（３）の不等式の左側の二次関数は、図５の下側の破線で表される。図５の下側の破線は、表１の各サンプルのうち、線径毎の引張強度が最も小さくなるサンプルを複数個用いて多項式近似によって求めたものである。式（３）の不等式の右側の二次関数は、図５の上側の破線で表される。図５の上側の破線は、表１及び表２で得られた各サンプルが２本の破線間に全て入るように、上記多項式を平行移動させることで求めたものである。 The quadratic function on the left side of the inequality in equation (3) is represented by the lower broken line in FIG. The lower broken line in FIG. 5 is obtained by polynomial approximation using a plurality of samples with the smallest tensile strength for each wire diameter among the samples in Table 1. The quadratic function on the right side of the inequality in equation (3) is represented by the upper dashed line in FIG. The upper broken line in FIG. 5 is obtained by translating the above polynomial so that each sample obtained in Tables 1 and 2 falls between the two broken lines.
　また、図５では、セリウムを含むタングステン線１の線径及び引張強度との関係についても示している。具体的な数値としては、表３に示されるとおりである。表３は、セリウム（Ｃｅ）を所定量含むタングステン線１の線径と引張強度とを示す表である。 FIG. 5 also shows the relationship between the wire diameter and tensile strength of the tungsten wire 1 containing cerium. Specific numerical values are as shown in Table 3. Table 3 is a table showing the wire diameter and tensile strength of the tungsten wire 1 containing a predetermined amount of cerium (Ce).
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　図５及び表３に示されるように、セリウムを含むタングステン線１も同様に、上記式（３）で表される関係を満たしている。ここでは、セリウムを例に挙げたが、セリウムと同様の特徴を有するランタン（Ｌａ）などの他の希土類元素を含んでも同様の結果が得られる。 As shown in FIG. 5 and Table 3, the tungsten wire 1 containing cerium similarly satisfies the relationship expressed by the above formula (3). Although cerium is taken as an example here, similar results can be obtained even if other rare earth elements such as lanthanum (La), which have similar characteristics to cerium, are included.
　［引張強度と真円率］
　次に、タングステン線１の引張強度と真円率との関係について説明する。 [Tensile strength and circularity]
Next, the relationship between the tensile strength and circularity of the tungsten wire 1 will be explained.
　＜レニウム（Ｒｅ）を含有する場合＞
　図６は、レニウムを含有する線径５０μｍのタングステン線について、Ｒｅ含有量と引張強度及び真円率との関係を示す図である。表４は、レニウムを所定量含み、線径が５０μｍのタングステン線の引張強度と真円率とを示す表である。 <When containing rhenium (Re)>
FIG. 6 is a diagram showing the relationship between Re content, tensile strength, and circularity for a tungsten wire containing rhenium and having a wire diameter of 50 μm. Table 4 is a table showing the tensile strength and circularity of a tungsten wire containing a predetermined amount of rhenium and having a wire diameter of 50 μm.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　図６及び表４に示されるように、Ｒｅ含有量が０．１ｗｔ％から０．５ｗｔ％に増えるに従い、引張強度が５２４０ＭＰａから５５７０ＭＰａまで急激に上昇した後、Ｒｅ含有量が１．０ｗｔ％から５．０ｗｔ％に増えるに従い、引張強度が５６９０ＭＰａの近傍まで緩やかに上昇する傾向が得られた。また、Ｒｅ含有量が０．１ｗｔ％から５ｗｔ％に増えるに従って、真円率は、０．４％から２．７％までほぼ一定の割合で増加していることが分かる。Ｒｅ含有量が３．０ｗｔ％以下の範囲では、真円率が２．０％以下であるのに対して、Ｒｅ含有量が５．０ｗｔ％になると真円率が２．０％より大きくなった。 As shown in Figure 6 and Table 4, as the Re content increases from 0.1 wt% to 0.5 wt%, the tensile strength increases rapidly from 5240 MPa to 5570 MPa, and then the Re content increases from 1.0 wt% to 5570 MPa. As the tensile strength increased to 5.0 wt%, there was a tendency for the tensile strength to gradually increase to around 5690 MPa. Furthermore, it can be seen that as the Re content increases from 0.1 wt% to 5 wt%, the circularity increases at a substantially constant rate from 0.4% to 2.7%. When the Re content is 3.0 wt% or less, the circularity is 2.0% or less, but when the Re content is 5.0 wt%, the circularity is greater than 2.0%. Ta.
　本実施の形態に係る線径５０μｍのタングステン線１では、５２００ＭＰａ以上の引張強度と、２．０％以下の真円率とを両立させることができている。また、Ｒｅ含有量が０．５ｗｔ％以上１．０ｗｔ％以下の範囲では、引張強度が５５００ＭＰａ以上で、かつ、真円率１．０％以下を実現できている。すなわち、高い引張強度と、より良化した真円率と、を両立させることができている。 The tungsten wire 1 with a wire diameter of 50 μm according to the present embodiment has both a tensile strength of 5200 MPa or more and a circularity of 2.0% or less. Further, when the Re content is in the range of 0.5 wt% or more and 1.0 wt% or less, the tensile strength is 5500 MPa or more and the circularity is 1.0% or less. That is, it is possible to achieve both high tensile strength and improved roundness.
　図７は、レニウムを含有する線径３０μｍのタングステン線について、Ｒｅ含有量と引張強度及び真円率との関係を示す図である。表５は、レニウムを所定量含み、線径が３０μｍのタングステン線の引張強度と真円率とを示す表である。 FIG. 7 is a diagram showing the relationship between Re content, tensile strength, and circularity for a tungsten wire containing rhenium and having a wire diameter of 30 μm. Table 5 is a table showing the tensile strength and circularity of a tungsten wire containing a predetermined amount of rhenium and having a wire diameter of 30 μm.
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
　図７及び表５に示されるように、Ｒｅ含有量が０．１ｗｔ％から０．５ｗｔ％に増えるに従い、引張強度が５４２０ＭＰａから５７７０ＭＰａまで急激に上昇した後、Ｒｅ含有量が１．０ｗｔ％から５．０ｗｔ％に増えるに従い、引張強度が５８９０ＭＰａまで緩やかに上昇する傾向が得られた。この傾向は、線径が５０μｍの場合と同様の傾向であるが、線径が小さくなることで、線径が５０μｍの場合に比べて、引張強度がより高くなっている。 As shown in Figure 7 and Table 5, as the Re content increases from 0.1 wt% to 0.5 wt%, the tensile strength increases rapidly from 5420 MPa to 5770 MPa, and then the Re content increases from 1.0 wt% to 5770 MPa. As the content increased to 5.0 wt%, the tensile strength tended to gradually increase to 5890 MPa. This tendency is similar to that when the wire diameter is 50 μm, but as the wire diameter becomes smaller, the tensile strength becomes higher than when the wire diameter is 50 μm.
　また、Ｒｅ含有量が０．１ｗｔ％から５ｗｔ％に増えるに従って、真円率は、０．３％から３．２％までほぼ一定の割合で増加していることが分かる。Ｒｅ含有量が３．０ｗｔ％以下の範囲では、真円率が２．０％以下であるのに対して、Ｒｅ含有量が５．０ｗｔ％になると真円率が２．０％より大きくなった。この傾向は、線径が５０μｍの場合と同様の傾向であるが、線径が小さくなることで引張強度が高くなったため、線径が５０μｍの場合に比べて、真円率の増加の割合が大きくなっている。 Furthermore, it can be seen that as the Re content increases from 0.1 wt% to 5 wt%, the roundness increases at an almost constant rate from 0.3% to 3.2%. When the Re content is 3.0 wt% or less, the circularity is 2.0% or less, but when the Re content is 5.0 wt%, the circularity is greater than 2.0%. Ta. This tendency is similar to that when the wire diameter is 50 μm, but as the wire diameter becomes smaller, the tensile strength increases, so the rate of increase in circularity is smaller than when the wire diameter is 50 μm. It's getting bigger.
　本実施の形態に係る線径３０μｍのタングステン線１では、５４００ＭＰａ以上の引張強度と、２．０％以下の真円率とを両立させることができている。また、Ｒｅ含有量が０．５ｗｔ％以上１．０ｗｔ％以下の範囲では、引張強度が５７５０ＭＰａ以上で、かつ、真円率１．０％以下を実現できている。すなわち、高い引張強度と、より良化した真円率と、を両立させることができている。 The tungsten wire 1 with a wire diameter of 30 μm according to the present embodiment has both a tensile strength of 5400 MPa or more and a circularity of 2.0% or less. Further, when the Re content is in the range of 0.5 wt% or more and 1.0 wt% or less, the tensile strength is 5750 MPa or more and the roundness is 1.0% or less. That is, it is possible to achieve both high tensile strength and improved roundness.
　このように、Ｒｅ含有量が０．１ｗｔ％以上３．０ｗｔ％以下の範囲では、従来よりも真円率が良化していることが分かる。また、Ｒｅ含有量が０．１ｗｔ％以上３．０ｗｔ％以下の範囲では、より高い引張強度を実現することができている。Ｒｅ含有量が０．５ｗｔ％以上１．０ｗｔ％以下の範囲では、より高い引張強度と、より良化した真円率と、を両立させることができている。なお、線径を小さくすることにより、より引張強度を高めることができる。 As described above, it can be seen that the roundness is better than before when the Re content is in the range of 0.1 wt% or more and 3.0 wt% or less. Furthermore, higher tensile strength can be achieved when the Re content is in the range of 0.1 wt% or more and 3.0 wt% or less. When the Re content is in the range from 0.5 wt% to 1.0 wt%, both higher tensile strength and improved roundness can be achieved. Note that by reducing the wire diameter, the tensile strength can be further increased.
　＜セリウム（Ｃｅ）を含有する場合＞
　図８は、セリウムを含有する線径３０μｍのタングステン線１について、Ｃｅ含有量と引張強度及び真円率との関係を示す図である。表６は、セリウム（Ｃｅ）を所定量含み、線径が３０μｍのタングステン線の引張強度と真円率とを示す表である。 <When containing cerium (Ce)>
FIG. 8 is a diagram showing the relationship between Ce content, tensile strength, and roundness of tungsten wire 1 containing cerium and having a wire diameter of 30 μm. Table 6 is a table showing the tensile strength and circularity of a tungsten wire containing a predetermined amount of cerium (Ce) and having a wire diameter of 30 μm.
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006
　図８及び表６に示されるように、セリウムの含有量（Ｃｅ含有量）が０．０２ｗｔ％から０．０９ｗｔ％に増えるに従い、引張強度が５４００ＭＰａから５７３０ＭＰａまで急激に上昇した後、Ｃｅ含有量が０．０９ｗｔ％から０．５０ｗｔ％に増えるに従い、引張強度が５９２０ＭＰａまで緩やかに上昇する傾向が得られた。Ｃｅ含有量が０．０３ｗｔ％以上であれば、引張強度が５５００ＭＰａ以上になっている。特に、Ｃｅ含有量が０．３０ｗｔ％以上になると、５９００ＭＰａ以上の高い引張強度が実現されている。 As shown in Figure 8 and Table 6, as the cerium content (Ce content) increases from 0.02wt% to 0.09wt%, the tensile strength increases rapidly from 5400MPa to 5730MPa, and then the Ce content increases. As the amount increased from 0.09 wt% to 0.50 wt%, the tensile strength tended to gradually increase up to 5920 MPa. If the Ce content is 0.03 wt% or more, the tensile strength is 5500 MPa or more. In particular, when the Ce content is 0.30 wt% or more, a high tensile strength of 5900 MPa or more is achieved.
　また、Ｃｅ含有量が０．０２ｗｔ％から０．５ｗｔ％に増えるに従って、真円率は、０．４％から３．１％までほぼ一定の割合で増加していることが分かる。Ｃｅ含有量が０．３０ｗｔ％以下の範囲では、真円率が２．０％以下であるのに対して、Ｃｅ含有量が０．５０ｗｔ％になると真円率が２．０％より大きくなった。また、Ｃｅ含有量が０．０３ｗｔ％以上０．０９ｗｔ％以下の範囲では、真円率が１．０％以下であり、真円率が良化されていることが分かる。 Furthermore, it can be seen that as the Ce content increases from 0.02 wt% to 0.5 wt%, the circularity increases at an almost constant rate from 0.4% to 3.1%. When the Ce content is 0.30 wt% or less, the circularity is 2.0% or less, but when the Ce content is 0.50 wt%, the circularity becomes greater than 2.0%. Ta. Moreover, it can be seen that when the Ce content is in the range of 0.03 wt% or more and 0.09 wt% or less, the roundness is 1.0% or less, and the roundness is improved.
　［効果など］
　以上のように、本実施の形態に係るタングステン線１は、タングステンを主成分として含む。引張強度をＴ（単位：ＭＰａ）とし、線径をＤ（単位：ｍｍ）とした場合に、４７５８×Ｄ２－７２５８．３×Ｄ＋５２７５．５≦Ｔ≦４７５８×Ｄ２－７２５８．３×Ｄ＋６１００を満たす。タングステン線１の真円率は、２．０％以下である。 [Effects etc.]
As described above, the tungsten wire 1 according to the present embodiment contains tungsten as a main component. When tensile strength is T (unit: MPa) and wire diameter is D (unit: mm), 4758×D 2 -7258.3×D+5275.5≦T≦4758×D 2 -7258.3×D+6100 satisfy. The circularity of the tungsten wire 1 is 2.0% or less.
　これにより、線径に応じた引張強度が従来よりも高く、かつ、真円率が良化した（すなわち、断面が真円に近い）タングステン線１を実現することができる。 As a result, it is possible to realize a tungsten wire 1 that has higher tensile strength depending on the wire diameter than conventional wires and has improved circularity (that is, the cross section is close to a perfect circle).
　また、例えば、タングステン線１は、レニウムを含んでもよい。この場合のタングステン線１におけるレニウムの含有量は、０．１ｗｔ％以上３ｗｔ％以下である。 Furthermore, for example, the tungsten wire 1 may contain rhenium. In this case, the content of rhenium in the tungsten wire 1 is 0.1 wt% or more and 3 wt% or less.
　これにより、真円率が良化し、かつ、引張強度がより高いタングステン線１を実現することができる。 Thereby, it is possible to realize a tungsten wire 1 with improved roundness and higher tensile strength.
　また、例えば、タングステン線１は、希土類元素を含んでもよい。この場合のタングステン線１における希土類元素の含有量は、０．０３ｗｔ％以上０．３ｗｔ％以下である。 Furthermore, for example, the tungsten wire 1 may contain a rare earth element. In this case, the content of rare earth elements in the tungsten wire 1 is 0.03 wt% or more and 0.3 wt% or less.
　これにより、真円率が良化し、かつ、引張強度がより高いタングステン線１を実現することができる。 Thereby, it is possible to realize a tungsten wire 1 with improved roundness and higher tensile strength.
　また、例えば、タングステン線１における希土類元素の含有量は、０．０３ｗｔ％以上０．０９ｗｔ％以下であってもよい。この場合のタングステン線１の真円率は、１．０％以下である。 Furthermore, for example, the content of rare earth elements in the tungsten wire 1 may be 0.03 wt% or more and 0.09 wt% or less. The circularity of the tungsten wire 1 in this case is 1.0% or less.
　これにより、真円率がより良化し、かつ、引張強度がより高いタングステン線１を実現することができる。 Thereby, it is possible to realize a tungsten wire 1 with improved roundness and higher tensile strength.
　また、例えば、タングステン線１の引張強度は、５８００ＭＰａ以上である。 Further, for example, the tensile strength of the tungsten wire 1 is 5800 MPa or more.
　これにより、タングステン線１をソーワイヤの芯線として利用した場合に、ソーワイヤを強く張ることが可能になるので、インゴットの切断時のソーワイヤの揺れを抑制することができる。ソーワイヤの揺れが抑制されることで、インゴットの切り代を小さくすることができるので、ロスを低減することができる。 As a result, when the tungsten wire 1 is used as a core wire of a saw wire, it is possible to tighten the saw wire strongly, so that shaking of the saw wire when cutting an ingot can be suppressed. By suppressing the swinging of the saw wire, the cutting allowance of the ingot can be made smaller, so that losses can be reduced.
　また、例えば、タングステン線１におけるタングステンの含有量は、９７ｗｔ％以上であってもよい。 Furthermore, for example, the content of tungsten in the tungsten wire 1 may be 97 wt% or more.
　また、例えば、タングステン線１の線径は、１００μｍ以下であってもよい。 Furthermore, for example, the wire diameter of the tungsten wire 1 may be 100 μm or less.
　これにより、線径が小さいので、タングステン線１を例えばソーワイヤに利用してインゴットのスライスに利用した場合には、切り代を小さくすることができ、ウェハの取り数を増やすことができる。 As a result, since the wire diameter is small, when the tungsten wire 1 is used, for example, as a saw wire to slice an ingot, the cutting allowance can be reduced and the number of wafers to be taken can be increased.
　また、例えば、タングステン線１は、ソーワイヤの芯線として用いられる。 Further, for example, the tungsten wire 1 is used as a core wire of a saw wire.
　これにより、真円率が良化したタングステン線１を利用して、例えばインゴットをスライスした場合、ウェハの厚みのばらつきを抑制することができる。つまり、品質の良いウェハを製造することができる。 As a result, when, for example, an ingot is sliced using the tungsten wire 1 with improved roundness, variations in the thickness of the wafer can be suppressed. In other words, high quality wafers can be manufactured.
　（その他）
　以上、本発明に係るタングステン線について、上記の実施の形態に基づいて説明したが、本発明は、上記の実施の形態に限定されるものではない。 (others)
Although the tungsten wire according to the present invention has been described above based on the above embodiments, the present invention is not limited to the above embodiments.
　例えば、タングステン線１は、レニウム、カリウム及び希土類元素のうちの２種類以上の元素を含有してもよい。 For example, the tungsten wire 1 may contain two or more elements of rhenium, potassium, and rare earth elements.
　また、例えば、タングステン線１は、ソーワイヤの芯線以外に利用されてもよい。例えば、タングステン線１は、メッシュのタテ糸及びヨコ糸として使用されてもよい。具体的には、タングステン線１を使用した製織加工が行われることで、タングステンメッシュが製造される。タングステンメッシュは、スクリーン印刷用のメッシュ又は耐切創用の衣類などに利用される。 Furthermore, for example, the tungsten wire 1 may be used for purposes other than the core wire of a saw wire. For example, the tungsten wire 1 may be used as the warp and weft threads of the mesh. Specifically, a tungsten mesh is manufactured by performing a weaving process using the tungsten wire 1. Tungsten mesh is used in screen printing meshes or cut-resistant clothing.
　あるいは、タングステン線１は、撚り線の単線として使用されてもよい。具体的には、タングステン線１を使用した撚り加工が行われることで、撚り線が製造される。撚り線は、ロープ又はカテーテルなどに利用される。 Alternatively, the tungsten wire 1 may be used as a single twisted wire. Specifically, a stranded wire is manufactured by performing a twisting process using the tungsten wire 1. Stranded wires are used for ropes, catheters, and the like.
　また、タングステン線１は、不織布、ナイロンなどの有機繊維との撚糸、又は、編み物に利用されてもよい。例えば、タングステン線１に対して所定の長さ以下になるように切断加工が行われた後、不織布加工が行われて、不織布が製造されてもよい。 Additionally, the tungsten wire 1 may be used for twisting or knitting with organic fibers such as nonwoven fabrics and nylon. For example, a nonwoven fabric may be manufactured by cutting the tungsten wire 1 to a predetermined length or less, and then performing a nonwoven fabric process.
　タングステン線１の真円率が良化することにより、加工時又は使用時にタングステン線１に加わる応力が均等になりやすい。すなわち、タングステン線１に対して局所的に大きい応力が加わるのが抑制されて断線などの発生を抑制することができる。 By improving the roundness of the tungsten wire 1, the stress applied to the tungsten wire 1 during processing or use tends to be uniform. That is, it is possible to suppress the application of large stress locally to the tungsten wire 1, thereby suppressing the occurrence of wire breakage and the like.
　その他、各実施の形態に対して当業者が思いつく各種変形を施して得られる形態や、本発明の趣旨を逸脱しない範囲で各実施の形態における構成要素及び機能を任意に組み合わせることで実現される形態も本発明に含まれる。 In addition, forms obtained by applying various modifications to each embodiment that those skilled in the art can think of, or by arbitrarily combining the constituent elements and functions of each embodiment without departing from the spirit of the present invention. The form is also included in the present invention.
１　タングステン線 1 Tungsten wire

Claims (8)

  1. 　タングステンを主成分として含み、
    　引張強度をＴ（単位：ＭＰａ）とし、線径をＤ（単位：ｍｍ）とした場合に、
    　４７５８×Ｄ２－７２５８．３×Ｄ＋５２７５．５≦Ｔ≦４７５８×Ｄ２－７２５８．３×Ｄ＋６１００
    を満たし、
    　真円率は、２．０％以下である、
    　タングステン線。     Contains tungsten as the main component,
    When the tensile strength is T (unit: MPa) and the wire diameter is D (unit: mm),
    4758×D 2 −7258.3×D+5275.5≦T≦4758×D 2 −7258.3×D+6100
    The filling,
    The roundness is 2.0% or less,
    tungsten wire.
  2. 　レニウムを含み、
    　前記タングステン線におけるレニウムの含有量は、０．１ｗｔ％以上３ｗｔ％以下である、
    　請求項１に記載のタングステン線。     Contains rhenium
    The content of rhenium in the tungsten wire is 0.1 wt% or more and 3 wt% or less,
    The tungsten wire according to claim 1.
  3. 　希土類元素を含み、
    　前記タングステン線における希土類元素の含有量は、０．０３ｗｔ％以上０．３ｗｔ％以下である、
    　請求項１に記載のタングステン線。     Contains rare earth elements,
    The content of rare earth elements in the tungsten wire is 0.03 wt% or more and 0.3 wt% or less,
    The tungsten wire according to claim 1.
  4. 　前記タングステン線における希土類元素の含有量は、０．０３ｗｔ％以上０．０９ｗｔ％以下であり、
    　前記タングステン線の真円率は、１．０％以下である、
    　請求項３に記載のタングステン線。     The content of rare earth elements in the tungsten wire is 0.03 wt% or more and 0.09 wt% or less,
    The circularity of the tungsten wire is 1.0% or less,
    The tungsten wire according to claim 3.
  5. 　前記タングステン線の引張強度は、５８００ＭＰａ以上である、
    　請求項１～４のいずれか１項に記載のタングステン線。     The tensile strength of the tungsten wire is 5800 MPa or more,
    The tungsten wire according to any one of claims 1 to 4.
  6. 　前記タングステン線におけるタングステンの含有量は、９７ｗｔ％以上である、
    　請求項１～３のいずれか１項に記載のタングステン線。     The content of tungsten in the tungsten wire is 97 wt% or more,
    The tungsten wire according to any one of claims 1 to 3.
  7. 　前記タングステン線の線径は、１００μｍ以下である、
    　請求項１～４のいずれか１項に記載のタングステン線。     The wire diameter of the tungsten wire is 100 μm or less,
    The tungsten wire according to any one of claims 1 to 4.
  8. 　前記タングステン線は、ソーワイヤの芯線として用いられる、
    　請求項１～４のいずれか１項に記載のタングステン線。     The tungsten wire is used as a core wire of a saw wire,
    The tungsten wire according to any one of claims 1 to 4.
PCT/JP2023/018418 2022-05-27 2023-05-17 Tungsten wire WO2023228833A1 (en)

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS607088A (en) * 1983-06-25 1985-01-14 東京タングステン株式会社 Tungsten wire for corona discharger
JPH02109640A (en) * 1988-10-18 1990-04-23 Sumitomo Electric Ind Ltd Electrode wire for electric discharging
JPH02145214A (en) * 1988-11-24 1990-06-04 Sumitomo Electric Ind Ltd Electricity discharge machining electrode wire
JPH0719840A (en) * 1993-07-06 1995-01-20 Toshiba Material Eng Kk Measuring method for roundness of wire rod
JP2005111653A (en) * 2003-09-16 2005-04-28 Tokyo Seiko Co Ltd Saw wire
CN113186438A (en) * 2021-01-20 2021-07-30 厦门虹鹭钨钼工业有限公司 Alloy wire and preparation method and application thereof
WO2021256204A1 (en) * 2020-06-19 2021-12-23 パナソニックＩｐマネジメント株式会社 Tungsten wire, saw wire, and tungsten wire for screen printing

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS607088A (en) * 1983-06-25 1985-01-14 東京タングステン株式会社 Tungsten wire for corona discharger
JPH02109640A (en) * 1988-10-18 1990-04-23 Sumitomo Electric Ind Ltd Electrode wire for electric discharging
JPH02145214A (en) * 1988-11-24 1990-06-04 Sumitomo Electric Ind Ltd Electricity discharge machining electrode wire
JPH0719840A (en) * 1993-07-06 1995-01-20 Toshiba Material Eng Kk Measuring method for roundness of wire rod
JP2005111653A (en) * 2003-09-16 2005-04-28 Tokyo Seiko Co Ltd Saw wire
WO2021256204A1 (en) * 2020-06-19 2021-12-23 パナソニックＩｐマネジメント株式会社 Tungsten wire, saw wire, and tungsten wire for screen printing
CN113186438A (en) * 2021-01-20 2021-07-30 厦门虹鹭钨钼工业有限公司 Alloy wire and preparation method and application thereof

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