Metal wire and metal mesh

Abstract

To provide a metal wire having a small wire diameter and excellent in tensile strength and straightness.SOLUTION: A metal wire is composed of tungsten or a tungsten alloy, has a wire diameter of 13 μm or less, a tensile strength of 4.8 GPa or more, and a natural hanging length per 1000 mm of 800 mm or more.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to metal wires and metal meshes. [Background technology]

[0002] Conventionally, tungsten wires that have a small diameter and high tensile strength have been known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-105548 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the conventional tungsten wire has a problem in that when the wire diameter is reduced while maintaining a high tensile strength, the straightness decreases.

[0005] Therefore, an object of the present invention is to provide a metal wire having a small diameter and excellent tensile strength and straightness, and a metal mesh including such a metal wire. [Means for solving the problem]

[0006] A metal wire according to one embodiment of the present invention is made of tungsten or a tungsten alloy, has a wire diameter of 13 μm or less, a tensile strength of 4.8 GPa or more, and a natural hanging length per 1000 mm of 800 mm or more.

[0007] A metal mesh according to one aspect of the present invention includes the metal wire according to the above aspect as warp or weft threads. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a metal wire or the like that has a small diameter and is excellent in tensile strength and straightness. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a metal mesh having metal wires according to an embodiment. [Figure 2A] FIG. 2A is a flowchart illustrating a method for manufacturing a metal wire according to an embodiment. [Figure 2B] FIG. 2B is a flowchart illustrating another example of the method for manufacturing a metal wire according to the embodiment. [Figure 3] FIG. 3 is a diagram showing the relationship between the straightness and tensile strength of the metal wire according to the embodiment. [Figure 4] FIG. 4 is a diagram showing the relationship between the wire diameter variation and the tensile strength of the metal wire according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Below, metal wires and metal meshes according to embodiments of the present invention will be described in detail with reference to the drawings. Each of the embodiments described below represents a specific example of the present invention. Therefore, the numerical values, shapes, materials, components, component arrangements and connection forms, steps, and step sequences shown in the following embodiments are merely examples and are not intended to limit the present invention. Therefore, among the components in the following embodiments, components not recited in the independent claims will be described as optional components.

[0011] Furthermore, each figure is a schematic diagram and is not necessarily an exact illustration. Therefore, for example, the scales of the figures do not necessarily match. Furthermore, in each figure, substantially the same components are given the same reference numerals, and redundant explanations are omitted or simplified.

[0012] Furthermore, in this specification, terms indicating the shape of an element, such as a circle, and numerical ranges are not expressions that express only a strict meaning, but are expressions that include a substantially equivalent range, for example, a difference of about a few percent.

[0013] (Embodiment) [composition] First, a metal wire according to an embodiment and a metal mesh including the metal wire will be described with reference to FIG.

[0014] FIG. 1 is a schematic diagram of a metal mesh 20 including metal wires 10 according to this embodiment. In FIG. 1, meshes are shown only in a portion of the metal mesh 20, but the entire metal mesh 20 is mesh-like. The metal mesh 20 includes a plurality of metal wires 10 as warp and weft threads, respectively. In other words, the metal mesh 20 is manufactured by weaving using a plurality of metal wires 10 as warp and weft threads, respectively.

[0015] The metal mesh 20 is, for example, a screen mesh used in screen printing. The metal mesh 20 has a plurality of openings 22. The openings 22 are portions through which ink passes during screen printing. Blocking a portion of the openings 22 with an emulsion or a resin (e.g., polyimide) forms a non-passing portion through which ink cannot pass. By patterning the shape of the non-passing portion into any shape, it becomes possible to perform screen printing in a desired shape.

[0016] When the metal mesh 20 is used for screen printing, the diameter of the metal wire 10 is gradually reduced to improve the accuracy of the screen printing. As the diameter is reduced, the cross-sectional area of ​​the metal wire 10 decreases, resulting in a significant decrease in absolute strength. For example, the tensile strength of a typical 13 μm tungsten wire is 3.4 GPa, and the absolute strength is 0.45 N. In contrast, the absolute strength of an 11 μm tungsten wire that has been reduced in diameter decreases to 0.32 N. To compensate for the decrease in absolute strength, an improvement in the strength per cross-sectional area, i.e., the tensile strength, is required. For example, a metal wire 10 with a wire diameter of 11 μm is required to have a tensile strength of 4.8 GPa or more.

[0017] The metal wire 10 is a tungsten wire made of tungsten (W) or a tungsten alloy wire made of a tungsten alloy. The tungsten content is 75 wt% or more. The tungsten content may be 80 wt% or more, 85 wt% or more, 90 wt% or more, 95 wt% or more, 99 wt% or more, 99.9 wt% or more, or 99.99 wt% or more.

[0018] The tungsten content is the ratio of tungsten to the weight of the metal wire 10. The same applies to the contents of other elements such as rhenium (Re) and potassium (K), which will be described later. The metal wire 10 may also contain unavoidable impurities that are inevitably mixed in during manufacturing.

[0019] The tungsten alloy is, for example, an alloy of rhenium and tungsten (ReW alloy). The rhenium content is, for example, 0.1 wt% or more and 10 wt% or less. The rhenium content may be 0.5 wt% or more, or 1 wt% or more. The rhenium content may also be 5 wt% or more.

[0020] A high rhenium content can increase the tensile strength of the metal wire 10. On the other hand, if the rhenium content is too high, it is difficult to thin the metal wire 10 while maintaining its high tensile strength. Specifically, wire breakage occurs more easily, making it difficult to draw long lengths. By lowering the rhenium content and increasing the tungsten content to 90 wt% or more, the workability of the metal wire 10 can be improved. Furthermore, by lowering the content of rare and expensive rhenium, it becomes possible to mass-produce long, inexpensive metal wires 10.

[0021] The wire diameter of the metal wire 10 is 13 μm or less. The smaller the wire diameter, the higher the opening ratio of the metal mesh 20 that can be manufactured, which can improve, for example, printing accuracy. The wire diameter of the metal wire 10 may be 12 μm or less, 10 μm or less, 8 μm or less, or 7 μm or less. The wire diameter of the metal wire 10 is, for example, 5 μm or more, but is not limited to this.

[0022] The wire diameter variation of the metal wire 10 is 1.0 μm or less. The wire diameter variation corresponds to the absolute difference between the maximum and minimum wire diameters of the metal wire 10. Therefore, the difference in wire diameter at any two points on the metal wire 10 is 1.0 μm or less. The wire diameter variation can be measured using, for example, a laser diameter measuring instrument, a scanning electron microscope (SEM), or a laser microscope. The wire diameter variation may be 0.6 μm or less, 0.5 μm or less, 0.4 μm or less, or 0.3 μm or less.

[0023] The cross-sectional shape of the metal wire 10 in a cross section perpendicular to the line axis is, for example, a circle, but is not limited to this. The cross-sectional shape of the metal wire 10 may be an oval, a square, a rectangle, or the like.

[0024] The tensile strength of the metal wire 10 is 4.8 GPa (=4800 MPa) or more. The tensile strength may be 4.9 GPa or more, 5.0 GPa or more, 5.1 GPa or more, or 5.2 GPa or more. The tensile strength can be measured, for example, based on the tensile test of the Japanese Industrial Standards (JIS H 4460 8).

[0025] The straightness of the metal wire 10 is expressed as the natural hanging length per 1000 mm. Specifically, the natural hanging length (i.e., straightness) per 1000 mm of the metal wire 10 is 800 mm or more. The straightness of the metal wire 10 may be 900 mm or more, 950 mm or more, or 970 mm or more. The natural hanging length can be measured, for example, based on the straightness test of the Japanese Industrial Standards (JIS H 4460 15).

[0026] As described above, the metal wire 10 according to the present embodiment has a small diameter and high tensile strength and straightness. In addition, the metal wire 10 has a high tungsten content and is therefore easy to process.

[0027] [Manufacturing method] Next, a method for manufacturing the metal wire 10 will be described with reference to Figures 2A and 2B. Figure 2A is a flowchart showing a method for manufacturing the metal wire 10 according to the present embodiment. Figure 2B is a flowchart showing another example of the method for manufacturing the metal wire 10 according to the present embodiment.

[0028] 2A, first, a tungsten ingot is prepared (S10). Specifically, an aggregate of tungsten powder is prepared, and the prepared aggregate is pressed and sintered to produce the tungsten ingot.

[0029] When manufacturing the metal wire 10 made of a tungsten alloy, a mixture of tungsten powder and metal powder (e.g., rhenium powder) in a predetermined ratio is prepared instead of the aggregate of tungsten powder. The average particle size of the tungsten powder and the rhenium powder is, for example, in the range of 3 μm to 4 μm, but is not limited thereto.

[0030] Next, the produced tungsten ingot is subjected to swaging (S12). Specifically, the tungsten ingot is forged and compressed from the periphery to be stretched and formed into a wire-shaped tungsten wire. Rolling may be performed instead of swaging.

[0031] For example, by repeatedly performing swaging, a tungsten ingot with a diameter of approximately 15 mm to approximately 25 mm is formed into a tungsten wire with a diameter of approximately 3 mm. Annealing is performed during the swaging process to ensure workability in subsequent processes. For example, annealing is performed at 2400°C for diameters in the range of 8 mm to 10 mm. However, in order to ensure tensile strength through grain refinement, annealing is not performed in the swaging process for diameters less than 8 mm.

[0032] Next, the tungsten wire is heated to 900°C before hot drawing (S14). Specifically, the tungsten wire is directly heated using a burner or the like. By heating the tungsten wire, an oxide layer is formed on the surface of the tungsten wire to prevent breakage during the subsequent hot drawing process.

[0033] Next, hot drawing is performed (S16). 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, the more easily the tungsten wire can be worked, making wire drawing easier. The hot drawing is performed repeatedly while changing the wire drawing dies. The cross-sectional area reduction rate of the tungsten wire in one drawing using one wire drawing die is, for example, 10% to 40%. In the hot drawing process, a lubricant in which graphite is dispersed in water may be used.

[0034] The hot drawing (S16) is repeated until the desired tungsten wire is obtained (No in S18). The desired wire diameter here is the wire diameter when there are two drawing cycles remaining, and is, for example, about 80 μm.

[0035] In the repeated hot drawing, a wire drawing die with a smaller hole diameter than the wire drawing die used in the previous wire drawing is used. Furthermore, in the repeated hot drawing, the tungsten wire is heated to a heating temperature lower than the heating temperature in the previous wire drawing. That is, the heating temperature is lowered in stages. The final heating temperature is, for example, 400°C, which contributes to the refinement of the crystal grains.

[0036] If a tungsten wire of the desired diameter is obtained and there are two remaining wiredrawing rounds (Yes in S18), room-temperature wiredrawing is performed (S20). As shown in FIG. 2B, electrolytic polishing may be performed (S19) before room-temperature wiredrawing (S20). Room-temperature wiredrawing achieves further refinement of the crystal grains by drawing the tungsten wire without heating. Room-temperature wiredrawing also has the effect of aligning the crystal orientation in the processing axis direction (specifically, the direction parallel to the wire axis of the metal wire 10).

[0037] Room temperature refers to a temperature in the range of 0°C to 50°C, for example, 30°C. Specifically, tungsten wire is drawn using multiple wire drawing dies with different hole diameters. Room-temperature wire drawing uses a liquid lubricant, such as a water-soluble one. Because no heating is performed during room-temperature wire drawing, evaporation of the liquid is suppressed. Therefore, the liquid lubricant can fully function. Unlike the traditional tungsten wire drawing method, which involves heating the wire at temperatures above 600°C, this method does not heat the tungsten wire and instead processes it while cooling it with a liquid lubricant. This suppresses dynamic recovery and dynamic recrystallization, contributes to grain refinement without wire breakage, and achieves high tensile strength.

[0038] The working ratio in cold drawing is, for example, 70% or more. The working ratio is expressed by the following formula (1) using the wire diameter Db immediately before cold drawing and the wire diameter Da immediately after cold drawing.

[0039] (1) Processing rate={1-(Da / Db) 2}×100

[0040] As can be seen from equation (1), the greater the reduction in wire diameter due to cold drawing, the greater the reduction ratio. For example, even if the wire diameter Db immediately before cold drawing is the same, the greater the reduction ratio, the smaller the wire diameter Da immediately after cold drawing. Increasing the reduction ratio increases the degree to which the tungsten wire is thinned by cold drawing, that is, a thinner tungsten wire can be obtained. The reduction ratio in cold drawing is 70% or more, but can also be 80% or more, 90% or more, or 95% or more. The wire diameter immediately after cold drawing is approximately in the range of 20 μm to 40 μm.

[0041] Next, after the room-temperature wiredrawing, low-temperature hot wiredrawing is performed (S22). 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 (room temperature) of the room-temperature wiredrawing (S20) and lower than the temperature of the heated wiredrawing (S16). Specifically, the temperature of the low-temperature hot wiredrawing is in the range of 100°C to 300°C, for example, 200°C or 300°C. The wire diameter after the low-temperature hot wiredrawing is in the range of approximately 10 μm to 16 μm.

[0042] Low-temperature hot wiredrawing is a new processing method in which the heating temperature is reduced by about 300°C compared to the usual heating temperature of 500°C to 600°C. This improves tensile strength and improves straightness or wire diameter variation. On the other hand, if wiredrawing is followed by processing at 500°C to 600°C, the tensile strength decreases and does not reach 4.8 GPa (Comparative Example 27 in Table 2 below).

[0043] Finally, the tungsten wire formed by low-temperature hot drawing is subjected to electrolytic polishing to finely adjust the diameter (S24). Electrolytic polishing is performed by immersing the tungsten wire and a counter electrode in an electrolyte solution such as a sodium hydroxide solution, and generating a potential difference between the tungsten wire and the counter electrode. The wire diameter after electrolytic polishing is 13 μm or less.

[0044] The metal wire 10 according to the present embodiment is manufactured through the above steps. By undergoing the above steps, the length of the metal wire 10 immediately after manufacture is, for example, 50 km or more, making it suitable for industrial use. The metal wire 10 can also be cut to an appropriate length depending on the mode of use, and used in the shape of a needle or rod.

[0045] Each step shown in the method for manufacturing the metal wire 10 is performed, for example, inline. Specifically, the multiple wiredrawing dies used in step S16 are arranged on the production line in order of decreasing hole diameter. A heating device such as a burner is disposed between each wiredrawing dies. An electrolytic polishing device may be disposed between each wiredrawing dies. Downstream (toward the subsequent process) of the wiredrawing die used in step S16, one or more wiredrawing dies used in step S20 and one or more wiredrawing dies used in step S22 are arranged in order of decreasing hole diameter, and an electrolytic polishing device is disposed downstream of the wiredrawing die with the smallest hole diameter. Each step may be performed individually.

[0046] Furthermore, the above-described method for manufacturing the metal wire 10 is merely an example, and the temperature, wire diameter, and the like in each step can be adjusted as appropriate.

[0047] As described above, in the method for manufacturing the metal wire 10 according to the present embodiment, hot drawing is performed at a first high temperature, followed by room-temperature drawing at a second room-temperature, and then low-temperature hot drawing is performed at a third low temperature. The third temperature is higher than the second temperature (room temperature) and lower than the first temperature (high temperature).

[0048] Thus, the metal wire 10 is manufactured by a new process called low-temperature hot wire drawing (also called low-temperature hot working). By performing low-temperature hot wire drawing, a metal wire 10 having a small wire diameter, a wire diameter deviation of 1.0 μm or less, and high tensile strength and straightness can be realized.

[0049] [Example] Below, several examples of the metal wire 10 according to the present embodiment will be described with reference to Table 1 and FIGS. 3 and 4, while comparing them with a metal wire according to a comparative example that was manufactured without low-temperature hot wiredrawing.

[0050] Table 1 below shows the material, processing method (wire drawing method), wire diameter, tensile strength, straightness (natural hanging length per 1000 mm), and wire diameter variation of examples and comparative examples of metal wire made of tungsten or tungsten alloy.

[0051] [Table 1]

[0052] [Table 2]

[0053] The relationship between straightness and tensile strength in each of the examples shown in Table 1 and each of the comparative examples shown in Table 2 is shown in Fig. 3. Fig. 3 is a diagram showing the relationship between straightness and tensile strength of the metal wire 10 according to the present embodiment. In Fig. 3, the horizontal axis represents the straightness of the metal wire 10 (natural hanging length per 1000 mm), and the vertical axis represents the tensile strength of the metal wire 10.

[0054] Furthermore, the relationship between the wire diameter variation and the tensile strength in each of the Examples shown in Table 1 and each of the Comparative Examples shown in Table 2 is shown in Fig. 4. Fig. 4 is a diagram showing the relationship between the wire diameter variation and the tensile strength of the metal wire 10 according to the present embodiment. In Fig. 4, the horizontal axis represents the wire diameter variation of the metal wire 10, and the vertical axis represents the tensile strength of the metal wire 10. Note that in Figs. 3 and 4, the numbers next to the plots represent the numbers of Examples 1 to 14 in Table 1 and Comparative Examples 21 to 28 in Table 2.

[0055] All of Examples 1 to 14 are metal wires produced according to the flowchart shown in Fig. 2A. Examples 1 to 14 are metal wires obtained by performing both room-temperature wiredrawing (S20) and low-temperature hot wiredrawing (S22) while appropriately adjusting processing conditions such as the material, target wire diameter, room-temperature wiredrawing processing rate, and low-temperature hot wiredrawing temperature.

[0056] Comparative Examples 21 and 22 are metal wires produced by performing room-temperature wiredrawing (S20) without performing low-temperature hot wiredrawing (S22). As shown in Table 2 and Fig. 3, it can be seen that high tensile strength is obtained by performing room-temperature wiredrawing, but straightness is low. Furthermore, as shown in Fig. 4, it can be seen that there is large variation in wire diameter and straightness is low.

[0057] Comparative Examples 23 to 26 are metal wires manufactured without carrying out either room temperature wiredrawing (S20) or low-temperature hot wiredrawing (S22). As shown in Table 2 and Figures 3 and 4, high tensile strength cannot be obtained without room temperature wiredrawing. In order to increase tensile strength, a room temperature wiredrawing step is necessary, but in this case, straightness decreases as in Comparative Examples 21 and 22.

[0058] In addition, Comparative Example 27 is a metal wire that was subjected to room temperature wiredrawing (S20) and then, instead of low-temperature hot wiredrawing (S22), was subjected to ordinary hot wiredrawing at a temperature of 500° C. to 600° C. As shown in Table 2 and Fig. 3, high straightness was obtained, but the tensile strength did not reach 4.8 GPa.

[0059] Thus, unless low-temperature hot wire drawing is performed, it is impossible to achieve both high tensile strength and high straightness. In a thin metal wire with a wire diameter of 13 μm or less, such as the metal wire of the comparative example, there is a trade-off between tensile strength and straightness. That is, increasing the tensile strength decreases straightness, and increasing the straightness decreases tensile strength.

[0060] In contrast, as shown in Table 1 and Fig. 3, Examples 1 to 14 achieved high tensile strength and high straightness. Furthermore, as shown in Fig. 4, high tensile strength and small wire diameter variation or high straightness were achieved. In other words, by performing low-temperature hot wire drawing, it is possible to obtain a metal wire 10 that achieves both high tensile strength and high straightness, even when the wire diameter is as thin as 13 µm or less. The metal wire 10 is a tungsten wire that does not contain rhenium, or a tungsten rhenium alloy wire with a rhenium content of 10 wt% or less, and therefore has excellent processability.

[0061] In addition, Examples 1 to 6 are tungsten rhenium alloy wires containing 1 wt% of rhenium, and Examples 7 to 14 are tungsten wires containing no rhenium. As can be seen from Table 1, when compared under the same wire diameter and the same drawing conditions, the tungsten rhenium alloy wires have slightly improved tensile strength compared to tungsten wires. This is due to the solid solution strengthening mechanism. In addition, dispersion strengthening, which occurs when oxides are precipitated at grain boundaries, also contributes to a certain degree of improvement in tensile strength.

[0062] Therefore, as the element that realizes this strengthening mechanism, even if other metal elements with different atomic radii are used instead of rhenium, the same effect can be obtained.That is, when metal wire 10 is made of tungsten alloy, the metal contained in tungsten alloy does not have to be rhenium.That is, tungsten alloy can also be the alloy of tungsten and one or more metals different from tungsten.

[0063] The metal other than tungsten is, for example, a transition metal, such as molybdenum (Mo), iridium (Ir), ruthenium (Ru) or osmium (Os), whose atomic radius is close to that of rhenium.The content of these metals is, for example, 0.1wt% or more and 10wt% or less, but is not limited thereto.For example, the content of the metal contained in the tungsten alloy may be less than 0.1wt% or more than 1wt%.

[0064] Furthermore, as can be seen from a comparison between Examples 3 and 4, by lowering the temperature in low-temperature hot wiredrawing, it is possible to increase the tensile strength while maintaining high straightness, even for the same wire diameter. As can be seen from a comparison between Examples 3 and 5, by increasing the processing rate in room-temperature wiredrawing, it is possible to increase the tensile strength while maintaining high straightness, even for the same wire diameter. A similar relationship exists for tungsten wires that do not contain rhenium, as can be seen from a comparison between Examples 9 to 14.

[0065] Furthermore, as can be seen from a comparison between Examples 3 and 4, by increasing the low-temperature hot wiredrawing temperature, it is possible to improve straightness while maintaining high tensile strength, even with the same wire diameter. A similar relationship is also observed in tungsten wires that do not contain rhenium, as can be seen from a comparison between Examples 9 to 14.

[0066] [Effects, etc.] As described above, the metal wire 10 according to the present embodiment is made of tungsten or a tungsten alloy, has a wire diameter of 13 μm or less, a tensile strength of 4.8 GPa or more, and a natural hanging length per 1000 mm of 800 mm or more. Also, for example, the wire diameter variation is 1.0 μm or less.

[0067] This makes it possible to realize a metal wire 10 that has a small diameter and is excellent in tensile strength and straightness.

[0068] Annealing and straightening, which involves heating a wire at a high temperature of approximately 1000°C after drawing or electropolishing, is a commonly known treatment for improving straightness. However, when the annealing and straightening treatment is performed on the metal wire of Comparative Example 21, for example, the straightness is improved but the tensile strength is reduced. For example, Comparative Example 28 in Table 2 is the metal wire of Comparative Example 21 that has been subjected to the annealing and straightening treatment. As can be seen from the comparison with Comparative Example 21, the annealing and straightening treatment improves the straightness, but at the expense of reducing the tensile strength to less than 4.8 GPa. In other words, the annealing and straightening treatment cannot achieve both high straightness and high tensile strength. Furthermore, the annealing and straightening treatment causes almost no change in the wire diameter variation, and therefore cannot reduce the wire diameter variation.

[0069] In contrast, the metal wire 10 according to the present embodiment is a metal wire that has not been subjected to anneal straightening treatment. Even without anneal straightening treatment, high straightness and high tensile strength can be achieved by low-temperature hot wire drawing.

[0070] Also, for example, the natural hanging length per 1000 mm is 900 mm or more.

[0071] This improves the straightness, which is useful for weaving the metal mesh 20, etc.

[0072] If metal wires with a diameter variation of more than 1.0 μm are used for weaving, uneven weaving is likely to occur. As a result, metal mesh with uneven weaving may have uneven height. If this metal mesh is used for a screen mesh, problems such as a decrease in screen printing accuracy may occur when it is pressed with a squeegee or the like.

[0073] Furthermore, when weaving is performed using a metal wire with a straightness of less than 800 mm, the wire may kink, causing problems such as wire breakage during weaving. When secondary processing of wire other than weaving, such as wire twisting, is performed using a metal wire with a straightness of less than 800 mm, problems such as wire breakage may occur.

[0074] In contrast to this, the metal mesh 20 according to the present embodiment includes the metal wires 10 as warp or weft threads. Also, for example, the metal mesh 20 is used as a mesh for screen printing.

[0075] As a result, the metal wire 10 has a small diameter and is excellent in tensile strength and straightness, so that the metal mesh 20 can be easily manufactured. Because the wire diameter is small, the metal mesh 20 can have a high opening ratio.

[0076] Furthermore, for example, the tungsten content may be 90 wt % or more.

[0077] As a result, for example, by reducing the content of other elements such as rhenium and increasing the content of tungsten, it is possible to realize a metal wire 10 that is excellent in workability.

[0078] (others) Although the metal wire and metal mesh according to the present invention have been described above based on the embodiments, the present invention is not limited to the above-described embodiments.

[0079] For example, in the above embodiment, the metal mesh 20 is a screen mesh, but this is not limiting. The metal mesh 20 may be used for a filter, protective clothing, or the like. All of the warp and weft threads of the metal mesh 20 may be metal wires 10, or at least one warp or weft thread may be metal wire 10, and the remaining warp or weft threads may be other metal wires such as stainless steel wires.

[0080] Furthermore, for example, the metal wire 10 may be used for purposes other than the wire material used for weaving the metal mesh 20. For example, the metal wire 10 may be used for saw wire, medical needles, ropes, strings, and the like.

[0081] Furthermore, for example, the content of tungsten contained in the metal wire 10 may be less than 75 wt %, or may be less than 70 wt %.

[0082] Furthermore, for example, the metal wire 10 may be made of tungsten doped with potassium (K). The doped potassium is present in the grain boundaries of the tungsten. The potassium (K) dispersed in the grain boundaries suppresses crystal coarsening during high-temperature heating and hot wiredrawing. However, since crystal coarsening does not occur during room-temperature wiredrawing, the amount of potassium (K) may be, for example, 0.010 wt% or less, while still providing a slight strength improvement effect during the process leading up to room-temperature wiredrawing. Potassium-doped tungsten wire, like tungsten alloy wire, can also achieve a tungsten wire with a tensile strength higher than the general tensile strength of piano wire. Similar effects can be achieved with oxides of other substances, such as cerium or lanthanum, rather than just potassium oxide.

[0083] The potassium-doped tungsten wire can be manufactured by the same manufacturing method as in the embodiment, by using potassium-doped tungsten powder instead of tungsten powder.

[0084] Furthermore, for example, the surface of the metal wire 10 may be coated with an oxide film, a nitride film, or a plating.

[0085] In addition, the present invention also includes forms obtained by applying various modifications to each embodiment that a person skilled in the art would think of, and forms realized by arbitrarily combining the components and functions of each embodiment within the scope of the present invention. [Explanation of symbols]

[0086] 10 Metal Wire 20 Metal Mesh

Claims

1. Made of tungsten or a tungsten alloy, The wire diameter is 13 μm or less, The tensile strength is 4.8 GPa or more, The natural drooping length per 1000 mm is 800 mm or more, The tungsten content is 90 wt % or more, The wire diameter variation is 1.0 μm or less. Metal wire.

2. The natural droop length per 1000 mm is 900 mm or more. The metal wire of claim 1 .

3. A metal mesh comprising the metal wire according to claim 1 or 2 as warp or weft.

4. Used as a mesh for screen printing, The metal mesh according to claim 3.

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