JP2024006448A - Tungsten wire and fiber product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tungsten wire that can achieve both low resistance and a fine diameter.

SOLUTION: A tungsten wire 1 has a specific resistance of 6.2 μΩ cm to 6.9 μΩ cm and a wire diameter of 50 μm or less, while comprising dislocations in crystal grains. For example, the tensile strength of the tungsten wire 1 is 2,200 MPa to 2,800 MPa.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to tungsten wire and textile products.

Patent Document 1 discloses a metal fiber that is a combination of a tungsten wire with a roughened surface and an aramid fiber or a nylon fiber.

JP 2018-80413 Publication

Tungsten has a high specific resistance value and high resistance compared to silver or copper. For example, in order to process tungsten into a wire and lower its resistance, the wire must be made thicker. That is, conventional tungsten wires cannot achieve both low resistance and small wire diameter.

Therefore, an object of the present invention is to provide a tungsten wire and a fiber product that can achieve both low resistance and a small wire diameter.

The tungsten wire according to one aspect of the present invention has a specific resistance value of 6.2 μΩ·cm or more and 6.9 μΩ·cm or less, a wire diameter of 50 μm or less, and includes dislocations in crystal grains.

A textile product according to one embodiment of the present invention includes the tungsten wire according to the above one embodiment.

According to the present invention, a tungsten wire and the like that can achieve both low resistance and a small wire diameter are provided.

FIG. 1 is a schematic diagram of a tungsten wire and a textile product according to an embodiment. FIG. 2 is a flowchart showing a method for manufacturing a tungsten wire according to an embodiment. FIG. 3A is an enlarged view of the surface of the tungsten wire according to Example 1. FIG. 3B is an enlarged view of the surface of the tungsten wire according to Example 2. FIG. 3C is an enlarged view of the surface of the tungsten wire according to Example 3. FIG. 3D is an enlarged view of the surface of the tungsten wire according to Example 4. FIG. 3E is an enlarged view of the surface of the tungsten wire according to Example 5. FIG. 3F is an enlarged view of the surface of the tungsten wire according to Example 6. FIG. 4A is an enlarged view of the surface of the tungsten wire according to Comparative Example 1. FIG. 4B is an enlarged view of the surface of the tungsten wire according to Comparative Example 2. FIG. 4C is an enlarged view of the surface of the tungsten wire according to Comparative Example 3. FIG. 4D is an enlarged view of the surface of the tungsten wire according to Comparative Example 4. FIG. 4E is an enlarged view of the surface of the tungsten wire according to Comparative Example 5. FIG. 4F is an enlarged view of the surface of the tungsten wire according to Comparative Example 6. FIG. 5A is an enlarged view showing the surface of the tungsten wire according to Example 1 at a higher magnification than FIG. 3A. FIG. 5B is an enlarged view showing the surface of the tungsten wire according to Example 2 at a higher magnification than FIG. 3B. FIG. 5C is an enlarged view showing the surface of the tungsten wire according to Example 3 at a higher magnification than FIG. 3C. FIG. 6A is an enlarged view showing the surface of the tungsten wire according to Comparative Example 2 at a higher magnification than FIG. 4B. FIG. 6B is an enlarged view showing the surface of the tungsten wire according to Comparative Example 3 at a higher magnification than FIG. 4C.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Below, tungsten wires and textile products according to embodiments of the present invention will be described in detail with reference to 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.

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.

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.

(Embodiment)
[composition]
First, the configuration of the tungsten wire and textile product according to this embodiment will be explained using FIG. 1. FIG. 1 is a schematic diagram showing a tungsten wire 1 and a textile product according to the present embodiment.

As shown in FIG. 1, a 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 of, for example, a meter order of about 100 meters to a kilometer order total length, but is not particularly limited.

The tungsten wire 1 shown in FIG. 1 can be subjected to secondary processing. That is, the tungsten wire 1 constitutes a part of the product by being processed. The product is, for example, a textile product including one or more tungsten wires 1 of a predetermined length. The textile product is a conductive fiber that utilizes the conductivity of the tungsten wire 1.

FIG. 1 shows a twisted yarn 10 as an example of a textile product. The twisted yarn 10 includes a tungsten wire 1 and an organic fiber 11 combined with the tungsten wire 1.

The twisted yarn 10 is a covering yarn having the organic fiber 11 as a core yarn and the tungsten wire 1 as a sheath yarn. For example, the twisted yarn 10 is manufactured by stretching and fixing the organic fiber 11 as a core yarn, and winding the tungsten wire 1 as a sheath yarn around the organic fiber 11 (that is, performing a covering process).

The tungsten wire 1 is wound along the outer surface of the organic fiber 11 at a predetermined pitch. As shown in FIG. 1, each turn of the tungsten wire 1 is spaced apart, but adjacent turns may be in close contact with each other. The specific structure and manufacturing method of the tungsten wire 1 will be explained later.

The organic fiber 11 is at least one fiber selected from the group consisting of synthetic fibers, natural fibers, and regenerated fibers. The organic fiber 11 is, for example, a synthetic fiber, such as an aramid fiber, a nylon fiber, or a polyethylene fiber. As the aramid fiber, for example, a fiber manufactured using an aromatic polyamide resin material such as Kevlar (registered trademark) can be used. As the polyethylene fiber, for example, a fiber manufactured using ultra-high molecular weight polyethylene such as Dyneema (registered trademark) can be used.

Note that the chemical fibers used as the organic fibers 11 are not limited to these, and polyester, polypropylene, polyurethane, polyvinyl chloride, acrylic, and the like can be used. Alternatively, the organic fiber 11 may be a semi-synthetic fiber or a regenerated fiber. Further, the organic fiber 11 may be a natural fiber such as a vegetable fiber or an animal fiber. For example, as the organic fiber 11, cotton, wool, silk, hemp, rayon, etc. can be used.

In addition, the twisted yarn 10 may be a covering yarn in which the core yarn is the tungsten wire 1 and the sheath yarn is the organic fiber 11. Alternatively, the twisted yarn 10 is not limited to a covering yarn, but may be a combined twisted yarn.

Moreover, the twisted thread 10 may be provided with a plurality of tungsten wires 1 without including the organic fibers 11. The twisted yarn 10 may be manufactured by subjecting a plurality of tungsten wires 1 to a twisting process (for example, a covering process or a combination-twisting process). Alternatively, the twisted yarn 10 may be a twisted yarn of the tungsten wire 1 and another metal wire such as a stainless steel wire.

Further, FIG. 1 shows a mesh 20 as an example of another textile product. The mesh 20 includes a plurality of tungsten wires 1. The mesh 20 is manufactured by weaving a plurality of tungsten wires 1 as warp threads and weft threads. The weave structure of the mesh 20 may be plain weave, twill weave, tatami weave, or satin weave, and is not particularly limited. The mesh 20 may be manufactured by using a plurality of tungsten wires 1 as knitting yarns and performing a knitting process such as stockinette knitting at a predetermined gauge number.

Note that the mesh 20 may be manufactured by weaving or knitting using the twisted threads 10. Moreover, the mesh 20 may be configured three-dimensionally. For example, mesh 20 may constitute a glove, hat, or garment.

Since the textile product such as the twisted yarn 10 or the mesh 20 includes the conductive tungsten wire 1, it can be used for vital sensing, for example. For example, textile products can sense the wearer's body temperature or pulse as examples of vital signs. Specifically, the tungsten wire 1 included in the textile product functions as a terminal for sensing vital signs. That is, the tungsten wire 1 can detect a weak current generated by the wearer.

Alternatively, the textile product may be provided with a separate terminal for sensing vital signs. In this case, the tungsten wire 1 functions as a wiring that electrically connects the terminal and the signal processing circuit.

The textile product may also be used for heat generation purposes. Specifically, a current can be passed through the tungsten wire 1 included in the textile product to generate heat.

The textile product may be clothing including gloves, clothing, headwear such as hats, footwear such as socks and tabi socks, and the like. Alternatively, the textile product may be a towel, washcloth, handkerchief, blanket, sheet, or the like.

Moreover, the textile product may be a nonwoven fabric manufactured by performing nonwoven fabric processing using the tungsten wire 1 and the organic fiber 11 as wire rods, respectively. Moreover, the textile product may be one in which the tungsten wire 1 or the twisted yarn 10 is gathered into a cotton-like shape. Alternatively, the textile product may be one in which the tungsten wire 1 is later sewn (embroidered or sewn) onto a textile fabric such as a woven fabric, knitted fabric, or braided fabric manufactured using organic fibers.

[Tungsten wire]
Next, a specific configuration of the tungsten wire 1 according to the present embodiment will be described.

The tungsten wire 1 is a metal wire containing tungsten (W) as a main component. The main component means that the content of the target element (here, tungsten) is greater than 50 wt%. For example, the content of tungsten in the tungsten wire 1 is 90 wt% or more. The content of tungsten may be 95 wt% or more, 99 wt% or more, or 99.9 wt% or more. Note that the tungsten content is the ratio of the weight of tungsten to the weight of the tungsten wire 1. The tungsten wire 1 may be a pure tungsten wire with a content of substantially 100 wt%. Note that the pure tungsten wire may contain unavoidable impurities that are unavoidable during manufacturing.

The tungsten wire 1 may be a tungsten alloy wire made of an alloy of tungsten and a metal element other than tungsten. Examples of metal elements other than tungsten include rhenium (Re), ruthenium (Ru), iridium (Ir), and osmium (Os). For example, the content of the metal element constituting the alloy (solid solution) such as rhenium is 0.1 wt% or more and 10 wt% or less, but is not limited thereto. The content of the metal elements constituting the alloy may be 0.5 wt% or more and 5 wt% or less. As an example, the rhenium content is 1 wt%, but may be 3 wt%.

Further, the tungsten wire 1 may be a doped tungsten wire doped with a predetermined element (doping element) such as potassium (K) or cerium (Ce). The content of the doping element is, for example, 0.005 wt% or more and 0.010 wt% or less, but is not limited thereto.

The wire diameter of the tungsten wire 1 is 50 μm or less. For example, the wire diameter of the tungsten wire 1 may be 40 μm or less, 30 μm or less, 20 μm or less, or 10 μm or less. For example, the wire diameter of the tungsten wire 1 may be about 5 μm.

The tensile strength of the tungsten wire 1 is 2200 MPa or more and 2800 MPa or less. This ensures sufficient tensile strength for use as textile products.

The average width of the surface crystal grains in the direction perpendicular to the line axis of the tungsten wire 1 is 220 nm or more. The average value of the width of the surface crystal grains (hereinafter referred to as average crystal width) is one of the parameters representing the size of the crystal grains constituting the tungsten wire 1. A specific measurement method will be explained later along with examples. The average crystal width is, for example, 220 nm or more and 310 nm or less.

When the average crystal width is 220 nm or more, the specific resistance value of the tungsten wire 1 becomes low. That is, as the size of the crystal grains of the tungsten wire 1 increases, the number of grain boundaries within the tungsten wire 1 decreases. When a current is passed through the tungsten wire 1, electric resistance occurs because the grain boundaries hinder the movement of electrons. In this embodiment, the specific resistance value of the tungsten wire 1 can be lowered by reducing the number of grain boundaries. Specifically, the specific resistance value of the tungsten wire 1 is 6.2 μΩ·cm or more and 6.9 μΩ·cm or less.

Dislocations are included in the crystal grains of the tungsten wire 1. A dislocation is a linear crystal defect. Dislocations occur during the wire drawing process (wire drawing process) in the method for manufacturing the tungsten wire 1. The generated dislocations substantially disappear (to the extent that they cannot be observed at a predetermined magnification) when heating (annealing) is performed at a predetermined temperature (for example, 1200° C.) or higher. In other words, the tungsten wire 1 containing dislocations to such an extent that it can be observed at a predetermined magnification means that it has not been heated above the predetermined temperature after the final wire drawing step.

Further, since dislocations are included in the crystal grains of the tungsten wire 1, the secondary workability of the tungsten wire 1 is improved. For example, when comparing the same wire diameter, the secondary workability of the tungsten wire 1 including dislocations is higher than the secondary workability of the tungsten wire without dislocations. Specifically, the flexibility (flexibility) of the tungsten wire 1 containing dislocations increases, making it possible to perform secondary processing involving bending or bending, such as twisting, weaving, and mesh processing using the tungsten wire 1. Become. This is because the propagation of the force applied to the tungsten wire 1 during secondary processing is suppressed by dislocations within the crystal grains, and the occurrence of disconnection of the tungsten wire 1 can be suppressed.

Note that dislocations do not occur to the extent that elastic deformation occurs. For example, when the tungsten wire 1 is wound around the winding frame 2 for storage as shown in FIG. 1, no dislocation occurs.

As described above, the tungsten wire 1 according to the present embodiment can achieve both low resistance and a small wire diameter. Further, the tungsten wire 1 according to the present embodiment can be subjected to secondary processing such as twisting, and the above-mentioned textile products can be manufactured.

[Production method]
Next, a method for manufacturing the tungsten wire 1 according to the present embodiment will be described using FIG. 2. FIG. 2 is a flowchart showing a method for manufacturing tungsten wire 1 according to this embodiment.

First, as shown in FIG. 2, a tungsten wire having a predetermined wire diameter (for example, about 3 mm) that is thicker than the final target wire diameter is drawn at a high degree of processing (S10). A tungsten wire having a predetermined wire diameter is produced by repeatedly performing swaging or rolling on a tungsten ingot. Moreover, a tungsten ingot is produced by preparing an aggregate of tungsten powder and performing pressing and sintering on the prepared aggregate. Note that a tungsten alloy wire or a doped tungsten wire can be manufactured by mixing powder of an alloying element or powder of a doping element with tungsten powder.

The degree of processing is the reduction rate of cross section due to wire drawing. Specifically, the working degree is a value obtained by subtracting from 1 the ratio of the cross-sectional area of the tungsten wire after drawing to the cross-sectional area of the tungsten wire before drawing, expressed as a percentage. The higher the working degree, the greater the reduction in cross-sectional area due to wire drawing, and the lower the working degree, the smaller the reduction in cross-sectional area due to wire drawing. That is, the wire diameter of a tungsten wire after being drawn at a high working degree is smaller than the wire diameter of a tungsten wire after being drawn at a low working degree for a tungsten wire having the same wire diameter.

In step S10, the high degree of machining is specifically a degree of machining of 80% or more. For example, line drawing is performed with a processing degree of 80% or more and 95% or less.

Wire drawing is performed using one or more wire drawing dies. In the wire drawing process, a lubricant in which graphite is dispersed in water may be used. Note that the tungsten wire may be annealed before the first wire drawing. By performing annealing, an oxide layer is formed on the surface of the tungsten wire. Thereby, occurrence of wire breakage during wire drawing can be suppressed.

If the next drawing is not the last drawing (No in S12), the tungsten wire is annealed (S14). By performing annealing, deterioration in wire drawing workability can be suppressed. The annealing temperature is, for example, a temperature of 1000° C. or more and 1600° C. or less, but is not limited thereto. After annealing is performed, the process returns to step S10 and wire drawing is performed at a high degree of processing. By repeating wire drawing (S10) and annealing (S14), the tungsten wire is thinned to a desired wire diameter. Electrolytic polishing may be performed during the repetition of wire drawing. Electropolishing can make the surface of the tungsten wire smooth, improve workability, and suppress the occurrence of wire breakage during wire drawing.

If the next drawing is the last drawing (Yes in S12), the tungsten wire is annealed (S16). The annealing temperature is 1200°C or more and 1600°C or less. This annealing temperature is, for example, higher than the temperature of the immediately preceding annealing (S14), but is not limited thereto.

Next, the tungsten wire that has been annealed (S16) is drawn at a low degree of processing (S18). The low degree of machining here is a degree of machining lower than the degree of machining in step S10. Specifically, the low degree of processing is 20% or more and 50% or less. For example, line drawing is performed with a processing degree of about 30%. By the final drawing in step S18, dislocations are formed within the crystal grains of the tungsten wire. Note that in the steps after step S18, annealing at a temperature of 1200° C. or higher is not performed.

If the degree of work in the final wire drawing is greater than 50%, the crystal grains become small and the specific resistance value cannot be lowered. If the degree of workability in the final wire drawing is less than 20%, dislocations will not be formed within the crystal grains and the secondary workability of the tungsten wire 1 will not be sufficiently improved.

Finally, the tungsten wire after drawing is subjected to electrolytic polishing (S20). Electrolytic polishing is performed, for example, by immersing the tungsten wire and the counter electrode in an electrolytic solution such as an aqueous sodium hydroxide solution, and generating a potential difference between the tungsten wire and the counter electrode. By electrolytic polishing, the wire diameter of the tungsten wire is slightly reduced and adjusted to a desired wire diameter. Note that electrolytic polishing (S20) may not be performed.

Through the above steps, the above-described tungsten wire 1 can be manufactured.

Further, 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 S10 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 S10, one or more wire drawing dies used in step S18 are arranged in order of decreasing hole diameter, and the wire drawing die with the smallest hole diameter is An electrolytic polishing device is arranged on the downstream side. Note that each step may be performed individually.

[Examples and comparative examples]
Next, specific examples and comparative examples of the tungsten wire 1 according to the present embodiment will be described.

The tungsten wires according to Examples 1 to 3 and Comparative Examples 1 to 3 have a wire diameter of 24 μm. The tungsten wires according to Examples 4 to 6 and Comparative Examples 4 to 6 have a wire diameter of 48 μm. Note that the tungsten content in Examples 1 to 6 and Comparative Examples 1 to 6 is 99.9 wt% or more.

The tungsten wire according to the example was manufactured according to the manufacturing method shown in FIG. 2. The tungsten wire according to the comparative example was manufactured using the manufacturing method shown in FIG. 2, in which drawing was performed at a high degree of work instead of drawing at a low degree of work in step S18, or the wire was annealed after the wire drawing. It is something. The specific manufacturing method of each Example and each Comparative Example is as follows. Note that in both Examples 1 to 6 and Comparative Examples 1 to 6, the processing method until the wire diameter reached 180 μm was the same.

<Example 1>
In Example 1, a tungsten wire with a wire diameter of 180 μm was annealed at 1500°C (S14), and then drawn at a processing rate of 80% (S12, two drawings before the last drawing). A tungsten wire with a wire diameter of 80 μm was prepared. Next, after performing annealing at 1100° C. (S14), wire drawing was performed at a workability of 86% (S12, one drawing before the final wire drawing) to create a tungsten wire with a wire diameter of 30 μm. Next, after performing annealing at 1200° C. (S16), wire drawing was performed at a workability of 30% (S18) to create a tungsten wire with a wire diameter of 25.1 μm. Thereafter, by performing electrolytic polishing (S20), a tungsten wire according to Example 1 having a wire diameter of 24 μm was created.

<Example 2>
In Example 2, the manufacturing method is almost the same as in Example 1, and the only difference is that the annealing before the final wire drawing in step S16 was performed at 1400°C.

<Example 3>
In Example 3, the manufacturing method is almost the same as in Example 1, and the only difference is that the annealing before the final wire drawing in step S16 was performed at 1600°C.

<Example 4>
In Example 4, a tungsten wire with a wire diameter of 180 μm was annealed at 1500°C (S14), and then drawn at a processing rate of 90% (S12, one drawing before the last drawing). A tungsten wire with a wire diameter of 57 μm was prepared. Next, after performing annealing at 1200° C. (S16), wire drawing was performed at a workability of 23% (S18) to create a tungsten wire with a wire diameter of 50 μm. Thereafter, by performing electrolytic polishing (S20), a tungsten wire according to Example 4 having a wire diameter of 48 μm was created.

<Example 5>
In Example 5, the manufacturing method is almost the same as in Example 4, and the only difference is that the annealing before the final wire drawing in step S16 was performed at 1400°C.

<Example 6>
In Example 6, the manufacturing method is almost the same as in Example 4, and the only difference is that the annealing before the final wire drawing in step S16 was performed at 1600°C.

<Comparative example 1>
In Comparative Example 1, a tungsten wire with a wire diameter of 180 μm was annealed at 1500° C., and then drawn at a processing rate of 80% (one drawing before the final wire drawing), resulting in a wire diameter of 80 μm. tungsten wire was created. Next, after annealing at 1100° C., wire drawing was performed at a workability of 91% (final wire drawing) to create a tungsten wire with a wire diameter of 25.1 μm. Thereafter, by performing electrolytic polishing (S20), a tungsten wire according to Comparative Example 1 having a wire diameter of 24 μm was created. Comparative Example 1 corresponds to a case where the degree of processing in the final wire drawing step (S18) is high in the manufacturing method of the present application.

<Comparative example 2>
In Comparative Example 2, a tungsten wire manufactured by the same manufacturing method as Comparative Example 1 was annealed at 1400° C. after the final wire drawing.

<Comparative example 3>
In Comparative Example 3, the tungsten wire manufactured by the same manufacturing method as Comparative Example 1 was annealed at 1600° C. after the final wire drawing.

<Comparative example 4>
In Comparative Example 4, a tungsten wire with a wire diameter of 180 μm was annealed at 1500° C., and then drawn at a processing rate of 94% (final wire drawing) to create a tungsten wire with a wire diameter of 50 μm. . Thereafter, by performing electrolytic polishing (S20), a tungsten wire according to Comparative Example 4 having a wire diameter of 48 μm was created. Comparative Example 4 corresponds to a case where the degree of processing in the final wire drawing step (S18) is high in the manufacturing method of the present application.

<Comparative example 5>
In Comparative Example 5, the tungsten wire manufactured by the same manufacturing method as Comparative Example 4 was annealed at 1400° C. after the final wire drawing.

<Comparative example 6>
In Comparative Example 6, the tungsten wire manufactured by the same manufacturing method as Comparative Example 4 was annealed at 1600° C. after the final wire drawing.

[Evaluation results]
Next, the results of measuring and evaluating the resistivity, tensile strength, average crystal width, and secondary workability of the tungsten wires according to Examples 1 to 6 and Comparative Examples 1 to 6 are shown in Table 1 and Table 1. This will be explained using Table 2 and FIGS. 3A to 6B. Examples 1 to 3 and Comparative Examples 2 and 3 were also evaluated for the presence or absence of dislocations.

3A to 3F are enlarged views showing the surfaces of tungsten wires according to Examples 1 to 6, respectively. 4A to 4F are enlarged views showing the surfaces of tungsten wires according to Comparative Examples 1 to 6, respectively. Each figure shows an SEM (Scanning Electron Microscope) image of the surface of the produced tungsten wire. In each figure, a range of the same density (color) represents one crystal grain. The left-right direction of each drawing is parallel to the line axis of the tungsten wire, and the surface crystal grains extend in a long direction along the line axis.

In each figure, a solid line L drawn vertically near the center is a straight line extending in a direction perpendicular to the line axis. The average value of the width of surface crystal grains, that is, the average crystal width, is determined by counting the number of boundaries between crystal grains (i.e., grain boundaries) along the solid line L within the range shown in each figure. It is calculated by Specifically, the average width of the surface grains is calculated by dividing the length of the counting range, that is, the length in the vertical direction of each figure, by the number of grain boundaries + 1. In each figure, a plurality of short line segments orthogonal to the solid line L each indicate the position of a grain boundary.

5A to 5C are views showing the surfaces of the tungsten wires according to Examples 1 to 3, respectively, enlarged at a higher magnification than FIGS. 3A to 3C. 6A and 6B are views showing the surfaces of tungsten wires according to Comparative Examples 2 and 3, respectively, enlarged at a higher magnification than FIGS. 4B and 4C.

In each of FIGS. 5A to 5C, the range in which dislocations contained within the crystal grains have been confirmed is surrounded by a solid line frame. In each figure, fine irregularities that appear to intersect with the line axis direction of the tungsten wire (in the left-right direction of the paper plane in the figure) correspond to dislocations. It can be seen that dislocations appear in all of Examples 1 to 3. Although not shown in the figure, Examples 4 to 6, which differ only in wire diameter from Examples 1 to 3, were manufactured by the same manufacturing method as Examples 1 to 3, so that It is assumed that dislocations are included.

On the other hand, as shown in FIGS. 6A and 6B, in Comparative Examples 2 and 3 in which annealing was performed after the final drawing, no dislocation was observed, unlike in FIGS. 5A to 5C. It is presumed that this is because recrystallization of crystal grains progresses due to annealing after drawing, and dislocations disappear.

Table 1 shows the evaluation results of the tungsten wires according to Examples 1 to 3 and Comparative Examples 1 to 3 (wire diameter: 24 μm). Table 2 shows the evaluation results of the tungsten wires according to Examples 4 to 6 and Comparative Examples 4 to 6 (wire diameter: 48 μm).

As shown in Table 1, the tungsten wires according to Examples 1 to 3 have lower specific resistance values than the tungsten wire according to Comparative Example 1. Specifically, the specific resistance improvement rates of Examples 1 to 3 were 5.6%, 9.6%, and 12.6%. Note that the specific resistance improvement rate is the value obtained by subtracting the ratio of the specific resistance value of the tungsten wire according to each example to the specific resistance value of the tungsten wire according to Comparative Example 1 from 1, expressed as a percentage. It can be seen that the higher the temperature of the final annealing (S16) is (for example, in Comparative Example 3 compared to Comparative Example 1), the lower the specific resistance and the higher the improvement rate.

The tungsten wires according to Comparative Examples 2 and 3 achieved specific resistance values equivalent to those of Examples 1 to 3. This is presumed to be because the annealing performed after the final drawing caused the crystal grains to enlarge due to recrystallization. The average crystal width has a correlation with each of resistivity and tensile strength. The larger the average crystal width, the lower the specific resistance value and the lower the tensile strength. The smaller the average crystal width, the higher the specific resistance value and the higher the tensile strength.

However, although Comparative Examples 2 and 3 achieved resistivity values similar to those of Examples 1 to 3, their secondary workability was low. This is presumably because no dislocations are included in the crystal grains, as shown in FIGS. 6A and 6B.

Note that in Tables 1 and 2, "secondary processing" indicates whether secondary processing using the tungsten wire according to each example or each comparative example is possible or impossible. Specifically, as a secondary process, twisting process using tungsten wire was performed. The twisting process is a predetermined twisting process performed on the target tungsten wire. Specifically, the tungsten wire was bent with a radius of curvature equal to the diameter of the tungsten wire.

"Not possible" in Tables 1 and 2 means that the tungsten wire broke during the twisting process, and the twisting process could not be performed. "Acceptable" means that the twisting process could be performed without breaking the tungsten wire.

All of the tungsten wires according to Examples 1 to 3 could be subjected to secondary processing. This is presumed to be because dislocations were included in the crystal grains, as described above. The tungsten wire according to Comparative Example 1 could also be subjected to secondary processing similarly to the example. However, the tungsten wire according to Comparative Example 1 has a high specific resistance value as described above. That is, in Comparative Example 1, a low resistivity value and high secondary workability could not be achieved.

On the other hand, in Comparative Examples 2 and 3, although the specific resistance values were low, secondary processing could not be performed. Specifically, when the above-mentioned twisting process was performed, the tungsten wire was brittle and broke. That is, in Comparative Examples 2 and 3 as well, it was not possible to realize a low resistivity value and high secondary workability.

As described above, in Examples 1 to 3, a tungsten wire with a wire diameter of 24 μm has both low resistivity and high secondary processability, whereas Comparative Examples 1 to 3 have a low specific resistance value and high secondary workability. It can be seen that both specific resistance value and high secondary workability cannot be achieved.

Regarding the tensile strength, the tungsten wires according to Examples 1 to 3 have lower tensile strengths than the tungsten wire according to Comparative Example 1. Although there is a decrease in tensile strength, sufficient tensile strength can be secured for use as textile products.

Further, as shown in Table 2, the tungsten wires according to Examples 4 to 6, which have wire diameters larger than those of Examples 1 to 3, exhibit the same tendency as Examples 1 to 3. Specifically, the tungsten wires according to Examples 4 to 6 have lower specific resistance values than the tungsten wire according to Comparative Example 4. More specifically, the specific resistance improvement rates of Examples 4 to 6 were 5.2%, 10.5%, and 12.6%.

The same trends as in Examples 1 to 3 were observed in the tensile strength, average crystal width, and secondary workability of Examples 4 to 6. That is, it can be seen that the tungsten wires according to each example can achieve both a low resistivity value and high secondary workability, regardless of the wire diameter.

As described above, in the tungsten wire 1 according to the present embodiment, annealing is performed before the final wire drawing, and then the final wire drawing is performed at a low processing rate. As a result, it is possible to obtain a tungsten wire 1 that has a small wire diameter, a low specific resistance value, and high secondary workability.

(summary)
The tungsten wire according to the first aspect of the present invention is, for example, the above-mentioned tungsten wire 1, and has a specific resistance value of 6.2 μΩ·cm or more and 6.9 μΩ·cm or less, and a wire diameter of 50 μm or less. , containing dislocations within the grains.

This makes it possible to achieve both low resistance and a small wire diameter. By lowering the specific resistance value, it is possible to achieve electrical resistance equivalent to that of a thick tungsten wire with a thin tungsten wire 1 (specifically, a reduction in cross-sectional area of about 5% to 13%). . Note that this rate of reduction in cross-sectional area corresponds to the specific resistance improvement rate described above.

Moreover, the tungsten wire according to the first aspect can realize high secondary workability by including dislocations in the crystal grains. That is, the tungsten wire according to the first aspect can be used for secondary processing into various products.

Further, the tungsten wire according to the second aspect of the present invention is the tungsten wire according to the first aspect, and has a tensile strength of 2200 MPa or more and 2800 MPa or less.

This ensures sufficient tensile strength for use as textile products.

Further, the tungsten wire according to the third aspect of the present invention is the tungsten wire according to the first aspect or the second aspect, and the average width of the surface crystal grains in the direction perpendicular to the line axis of the tungsten wire is 220 nm or more. It is.

Thereby, a low specific resistance value can be achieved.

A textile product according to a fourth aspect of the present invention includes the tungsten wire according to any one of the first to third aspects.

As a result, since the specific resistance value of the tungsten wire is low, the textile product can be used for vital sensing, etc. that utilizes the conductivity of the tungsten wire. Furthermore, the thin wire diameter of the tungsten wire is useful in textile products that are directly touched and used by people, such as clothing and towels. For example, if the wire diameter is large, the feel will be poor, but since the wire diameter of the tungsten wire according to this embodiment is small, it is possible to realize a textile product that is comfortable to the touch.

Further, the textile product according to the fifth aspect of the present invention is the textile product according to the fourth aspect, and is the twisted yarn 10 or the mesh 20.

This makes it possible to apply it to various clothing items.

(others)
Although the tungsten wire and textile products according to the present invention have been described above based on the above-described embodiments, the present invention is not limited to the above-described embodiments.

For example, although an example has been shown in which a tungsten wire is fabricated into a textile product by secondary processing, the present invention is not limited thereto. The tungsten wire may be used, for example, as an electrode for electrical discharge machining.

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 Tungsten wire 10 Twisted yarn (textile products)
20 Mesh (textile products)

Claims (5)

The specific resistance value is 6.2 μΩ·cm or more and 6.9 μΩ·cm or less,
The wire diameter is 50 μm or less,
Contains dislocations within grains,
tungsten wire. The tensile strength is 2200 MPa or more and 2800 MPa or less,
The tungsten wire according to claim 1. The average value of the width of the surface crystal grains in the direction perpendicular to the line axis of the tungsten wire is 220 nm or more,
The tungsten wire according to claim 1 or 2. A textile product comprising the tungsten wire according to claim 1 or 2. The textile product is a thread or a mesh.
The textile product according to claim 4.

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