Rhenium-tungsten wire, medical needle, probe pin, thermo-couple, and electronic tube heater

Abstract

To provide an ReW wire which facilitates long-term storage by suppressing discoloration.SOLUTION: The amount of NH4 on the surfaces of the wires is equal to or less than the amount of NH4, which is obtained by dividing the weight of 10massppm ions on the surfaces of the wires by the weight of the wires. A medical needle and a probe pin according to an embodiment use the rhenium-tungsten alloy wire according to the embodiment.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The embodiments described below relate to a rhenium-tungsten alloy wire, a manufacturing method thereof, a medical needle, and a probe pin. [Background technology]

[0002] Tungsten alloy (ReW) wire containing a certain amount of rhenium (Re) has improved electrical resistance and wear resistance compared to regular tungsten (W) wire. It also has improved tensile strength over a wide temperature range and ductility after recrystallization. For this reason, it is used in semiconductor inspection probe pins, heaters for electron tubes, filaments for vibration-resistant light bulbs, thermocouples, fluorescent display filaments, medical needles, etc.

[0003] After the surface compound layer created during the manufacturing process is removed by electrolytic polishing or other methods, ReW wire retains a silvery white color with a metallic luster. However, as the storage period increases, the surface discolors, for example, to blue, yellow, or reddish purple. Discoloration can cause changes in the electrical resistance of probe pins. In display tube filaments, the oxide coating (electrodeposition surface treatment) that emits thermions becomes uneven. In medical needles, if heat treatment is performed in a discolored state, the mechanical properties deteriorate, and the wire may break during bending or other processes. Furthermore, quality degradation and impurity can become an issue, such as changes in friction in the discolored area and the risk of the discolored area falling off.

[0004] As a result, the discolored parts are unusable and require additional processing, such as re-electrolysis. Furthermore, additional processing changes the wire size, electrical resistance, and strength, making it unusable and reducing yield. For this reason, after the electrolysis process, the wire is thoroughly dried, and the wound wire spool is sealed and packaged under reduced pressure and stored away from the external environment. However, there is variation in the degree of discoloration among ReW wires stored in the same manner. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 4-308003 [Patent Document 2] Patent Publication No. 2021-95585 [Non-patent literature]

[0006] [Non-Patent Document 1] Saburo Nagakura and five others, "Iwanami Dictionary of Physics and Chemistry, 5th Edition," Iwanami Shoten, February 1998, p. 541 Summary of the Invention [Problem to be solved by the invention]

[0007] The problem to be solved by the present invention is to provide a ReW wire that can be easily stored for a long period of time by suppressing discoloration. [Means for solving the problem]

[0008] In order to solve the above-mentioned problem, the rhenium-tungsten alloy wire of the embodiment is made of the tungsten alloy containing rhenium, and the NH4 amount of the wire surface, calculated by the NH4 ion weight of the wire surface / alloy wire weight, is 10 mass ppm or less.The rhenium content in the alloy is 2 wt% or more but less than 30 wt%. [Brief explanation of the drawings]

[0009] [Figure 1a] Figure 1a shows an example of the results of a TDS analysis of an undiscolored part of a ReW wire. [Figure 1b] Figure 1b shows an example of the results of a TDS analysis of a discolored area of ​​a ReW wire. [Figure 2] FIG. 2 is a cross-sectional view of a test apparatus for evaluating the effect of NH4 on ReW wire. [Figure 3] FIG. 3 is a graph showing the discoloration of the ReW line and its reflectance spectrum. [Figure 4]Figure 4 shows an example of the results of X-ray photoelectron spectroscopy (XPS) analysis of a discolored sample (CW) and a non-discolored sample (NW). [Figure 5] FIG. 5 is an explanatory diagram of particle size distribution. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, the rhenium-tungsten alloy wire of embodiment will be described with reference to drawings.Hereinafter, rhenium-tungsten alloy wire may be referred to as ReW wire.It should be noted that drawings are only schematic, and for example, the dimensional ratio of each part is not limited to drawings.

[0011] The rhenium tungsten alloy wire according to the embodiment is a wire made of a tungsten alloy containing rhenium, and the amount of NH4 on the wire surface, calculated by the weight of NH4 ions on the wire surface / weight of the alloy wire, is 10 massppm or less.

[0012] Among rhenium oxides, Re2O5, also known as rhenium pentoxide, is a blue compound. ReO3, also known as rhenium trioxide, is a red cubic crystal with a metallic luster. Re2O7, also known as rhenium heptoxide, is a yellow orthorhombic crystal (Non-Patent Document 1). As such, rhenium oxides have color, and the color changes depending on the type of oxide. As a result of extensive research, it was discovered that the discoloration of ReW wire is caused by rhenium oxide, and furthermore, that NH4 has an effect.

[0013] Figures 1a and 1b show examples of the results of TDS analysis of the undiscolored part (A) and discolored part (B) of a ReW wire. The equipment used was a TDS1200II quadrupole mass spectrometer manufactured by Denshi Kagaku Co., Ltd. The length of the evaluation sample was 1 cm, and measurements were performed at temperatures ranging from room temperature to 1400°C. Compared to the undiscolored part (A), B (discolored part) showed significant desorption of NH3 (m / z = 17, 16) and HO (m / z = 18, 17).

[0014] To confirm the effect of NH4, a forced test was conducted in which ammonia water was placed in a sealed container. Figure 2 shows a cross section of the test equipment. The electropolished sample (X) was placed on a spool on the mesh stand (Y) of the test equipment, and the sample (X) was sealed in the equipment and left for four days. When ammonia water was placed in the sealed container (Z) located below the mesh stand (Y) and left there, the ammonia atmospheric concentration inside the equipment was 3.5%.

[0015] Test 1 used a doped tungsten wire that had been electrolyzed and had no discoloration. Test 2 used a 26% Re-W wire that had discolored after storage and was re-electrolyzed. Test 3 used a 26% Re-W wire that had not discolored after storage and was re-electrolyzed. Table 1 shows the test results. The doped tungsten (W) wire did not discolor, regardless of the ammonia atmosphere. The ReW wire discolored only in the ammonia atmosphere, with Re affecting the discoloration and the presence of NH4 accelerating the discoloration. Note that in Table 1, no ammonia water was installed (blank in Figure 2) because the test was conducted with water placed in the sealed container (Z) instead of ammonia water.

[0016] [Table 1]

[0017] Figure 3 shows the discoloration of the ReW line and its reflectance spectrum. The discoloration exhibits the aforementioned rhenium oxide colors (blue, purple (red-blue), and yellow). The reflectance spectrum of each discolored area was measured using a microspectroscopic system (Techno-Synergy, DF-1037), which incorporates a spectroscopic system into a microscope and enables spectroscopic measurement of minute spots. The measurement spot diameter was approximately 10 μm, the exposure time was 10 ms, and the number of measurements was 200. For the visible light wavelengths of 400 nm to 700 nm, the difference between the maximum and minimum reflectance values ​​for the undiscolored silvery white (metallic color) was less than 5%. In contrast, the discolored areas exhibited changes in reflectance, with peaks at wavelengths corresponding to each color that were more than 5% off the minimum value. From this, discolored areas could be identified by visual inspection or by whether the difference between the maximum and minimum reflectance values ​​in the 400 nm to 700 nm wavelength range of the reflectance spectrum exceeded 5%.

[0018] Figure 4 shows an example of the results of X-ray photoelectron spectroscopy (XPS) analysis of a discolored sample (CW) and a non-discolored sample (NW) using a 0.152mm diameter 26wt% Re-W beam that had been electrolytically polished to a metallic luster and then stored for a certain period of time. The equipment used was a PHI Quantera SXM, with a single crystal spectrometer A1Kα beam as the X-ray source, an X-ray output of 12.5W, and an analysis range of 50μm diameter.

[0019] In the NW (non-discolored sample) shown in Figure 4B, W-Metal and tungsten oxide (WO x ) was detected more than in the CW (discolored sample) shown in Figure 4A, and rhenium oxide (ReO x ) was detected in greater amounts than NW, as shown in Figure 4B. As mentioned above, rhenium oxides have color, and the color changes depending on the type of oxide. In other words, it was found that rhenium oxides are the cause of the color change, and furthermore, the presence of NH4 promotes the formation of rhenium oxides.

[0020] Table 2 shows the results of measuring the amount of NH4 in the discolored and non-discolored areas using hot water extraction-ion chromatography. The amount of NH4 was measured by hot water extraction of 0.5 g of alloy wire into 50 ml of pure water and then measuring it using ion chromatography. The ICS-2000 instrument manufactured by Thermo Fischer Scientific was used. As a result, it was found that discoloration can be suppressed by limiting the amount of NH4 attached to the surface. Note that Sample 1 in Table 2 corresponds to the discolored sample (A(CW)) whose results are shown in Figure 4, and Samples 2, 3, and 4 correspond to the non-discolored sample (B(NW)) whose results are shown in Figure 4.

[0021] The reason for ammonium ions being mixed into rhenium-tungsten alloy wire is believed to be as follows: Ammonia contained in the air is adsorbed during the manufacturing process of rhenium-tungsten alloy wire. Ammonia in the air is generated when organic matter from plants and animals, as well as ammonium salts, is decomposed by bacteria, and it is believed to be primarily generated naturally in the soil and oceans. In urban areas, ammonia may also be generated from sewers, sewage treatment plants, chemical plants, refineries, and the combustion of fossil fuels. Furthermore, the lubricant used in the drawing process, described below, may be a turbid liquid made by dissolving graphite powder in water. Ammonia water is added to the lubricant to adjust the pH. These are believed to be the causes.

[0022] [Table 2]

[0023] In the embodiment of the rhenium-tungsten alloy wire, the amount of NH4 on the wire surface, calculated by the weight of NH4 ions on the wire surface / weight of the alloy wire, is 10 massppm or less, and even 5 massppm or less.By suppressing the amount of NH4 present on the surface to 10 massppm or less, and even 5 massppm or less, discoloration can be suppressed, and when used as a material for probe pins or medical needles, it can be manufactured with good yield.

[0024] The amount of NH4 on wire surface can be set to the target value by, for example, adjusting the surface treatment of rhenium-tungsten alloy wire, for example, the electrolytic polishing conditions, cleaning conditions or drying conditions of rhenium-tungsten alloy wire.In addition, the amount of NH4 on wire surface can be set to the target value by adjusting the storage method or packaging method of rhenium-tungsten alloy wire.Adjustment can be carried out by each of the above methods alone or by combining multiple methods.

[0025] The rhenium content of the ReW wire of the embodiment is, for example, 2 wt% or more and less than 30 wt%. The rhenium content of the ReW wire of the embodiment is, for example, preferably, 10 wt% or more and 28 wt% or less. The rhenium content is a value analyzed by inductively coupled plasma-optical emission spectrometry (ICP-OES). Rhenium improves the elongation of tungsten at high temperatures and enhances its workability. It also increases strength through solid solution strengthening.

[0026] If the rhenium content is less than 2 wt%, the effect is insufficient. For example, if a ReW wire with a rhenium content of less than 2 wt% is used as a probe pin material, the finished probe pin will deform significantly with frequent use, resulting in poor contact and reduced semiconductor inspection accuracy. If the rhenium content exceeds 30 wt%, the rhenium content exceeds the solid solubility limit with tungsten, making it impossible to diffuse and homogenize (solid-solve) rhenium into the tungsten matrix. As a result, there is a risk of the formation of phase regions with a locally high rhenium composition ratio (σ-phase segregation phase). If such regions appear on the surface, they are prone to discoloration.

[0027] When a probe pin or medical needle is manufactured using a ReW wire containing 2 wt% or more but less than 30 wt% of rhenium, discoloration can be suppressed, production yield can be improved, and the mechanical properties (strength and abrasion resistance) of the manufactured probe pin or medical needle can be ensured. The rhenium content is preferably, for example, 10 wt% or more but less than 28 wt%.

[0028] The ReW wire of the embodiment may contain 30 wtppm to 90 wtppm of potassium (K) as a dopant. The potassium content is a value analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES). The inclusion of potassium improves the tensile strength and creep strength at high temperatures due to the doping effect.

[0029] If the potassium content is less than 30 wtppm, the doping effect will be insufficient. If the potassium content exceeds 90 wtppm, workability will decrease, which may significantly reduce yield. By including potassium as a dopant in an amount of 30 wtppm to 90 wtppm, for example, thin wires for thermocouples and electron tube heaters made from the ReW wire of the embodiment can be produced with a high yield while maintaining high-temperature properties (preventing breakage and deformation when used at high temperatures).

[0030] The ReW wire of the embodiment has a diameter of, for example, 0.1 mm or more and 1.00 mm or less.

[0031] The ReW wire of this embodiment is prevented from surface discoloration, which contributes greatly to long-term storage and improved yield. The ReW wire of this embodiment can also be used for medical needles, thermocouples, and probe pins.

[0032] Next, a method for manufacturing a ReW wire according to the embodiment will be described. The manufacturing method is not particularly limited, but the following method can be given as an example.

[0033] Tungsten powder and rhenium powder are mixed so that the rhenium content is 2 wt% or more and less than 30 wt%. While the mixing method is not particularly limited, a method in which the powders are slurried using water or an alcohol-based solution and mixed is particularly preferred because it produces powder with good dispersibility. Furthermore, to ensure the homogeneity of the powder lot, it is even more preferable to dry the slurry and then dry-mix the same powder lot together.

[0034] The rhenium powder to be mixed preferably has an average particle size of less than 8 μm. The particle size distribution preferably has an SD value of less than 11 μm. Figure 5 shows an explanatory diagram of particle size distribution. The horizontal axis represents particle size (μm), the left vertical axis represents frequency (%), and the right vertical axis represents cumulative (%). The SD value is calculated by SD = (d(84%) - d(16%)) / 2, where d(84%) is the cumulative 84% particle size and d(16%) is the cumulative 16% particle size. This value serves as a guide to the distribution width of the measured particle size. The particle size distribution is measured using a laser diffraction method. The amount of powder used per measurement should be the amount recommended for the measuring device. Generally, 0.02 g is recommended. The measurement sample should be thoroughly stirred before weighing.

[0035] The tungsten powder is either pure tungsten powder excluding unavoidable impurities, or doped tungsten powder containing potassium (K) in an amount that takes into account the yield of wire rod. The tungsten powder preferably has an average particle size of less than 16 μm. The particle size distribution preferably has an SD value of less than 13 μm. When the average particle size of the rhenium powder is 8 μm or more, when the SD value of the rhenium powder is 11 μm or more, when the average particle size of the tungsten powder is 16 μm or more, or when the SD value of the tungsten powder is 13 μm or more, the diffusion distance of the rhenium atoms or tungsten atoms increases in order to diffuse and homogenize (solid-solve) the rhenium into the tungsten matrix, making it easier to form a σ phase.

[0036] The ratio of the average particle size of the rhenium powder to the average particle size of the tungsten powder (average particle size of Re / average particle size of W) is preferably 0.4 or more and 2.0 or less. If the ratio of the average particle size of the rhenium powder to the average particle size of the tungsten powder is less than 0.4 or exceeds 2.0, the diffusion distance of the rhenium atoms to the center of the tungsten particle, or the diffusion distance of the tungsten atoms to the center of the rhenium particle, becomes long, and the σ phase may be easily generated.

[0037] Next, the mixed powder is placed in a predetermined mold and press-molded. The pressing pressure at this time is preferably 150 MPa or higher. To facilitate handling, the molded body may be pre-sintered at 1200 to 1400°C in a hydrogen furnace. The resulting molded body is sintered in a hydrogen atmosphere, an inert gas atmosphere such as argon, or a vacuum. The sintering temperature is preferably 2500°C or higher. If the sintering temperature is lower than 2500°C, the diffusion of rhenium atoms and tungsten atoms during sintering will not proceed sufficiently. The upper limit of the sintering temperature is 3400°C (below the melting point of tungsten, 3422°C).

[0038] The relative density of the sintered body (relative density to true density (%) = [sintered body density / true density] × 100%) is preferably 90% or more. Furthermore, the ratio of the density of the lowest part of a sintered body, for example, the bottom end in electric sintering, to the overall average density of the same sintered body is preferably 0.98 or more. By making the relative density of the sintered body 90% or more and the ratio of the density of the lowest part to the overall average density of the same sintered body 0.98 or more, fluctuations in the rhenium content can be suppressed.

[0039] The sintered body obtained in this sintering step is subjected to a first swaging (SW) process. The first swaging process is preferably carried out at a heating temperature of 1300 to 1600°C. The reduction rate of the cross-sectional area (area reduction rate) in one heat treatment (one heat) is preferably 5 to 15%.

[0040] Rolling may be performed instead of the first rolling and punching process. The rolling is preferably performed at a heating temperature of 1200 to 1600°C. The area reduction rate per heat is preferably 40 to 75%. As the rolling mill, a two-way roller rolling mill, a four-way roller rolling mill, a die roll rolling mill, or the like can be used. Rolling can significantly improve manufacturing efficiency. The first rolling and punching (SW) process may be combined with rolling.

[0041] The sintered body (ReW bar) that has been subjected to the first rolling, rolling, or a combination of the first rolling and rolling is subjected to the second rolling (SW) process. The second rolling is preferably performed at a heating temperature of 1200 to 1500°C. The area reduction rate per heating (one heat) is preferably about 5 to 20%.

[0042] The ReW bar that has undergone the second rolling process is then subjected to a recrystallization treatment, which can be carried out using, for example, a high-frequency heating device in a hydrogen atmosphere, an inert gas atmosphere such as argon, or a vacuum at a treatment temperature in the range of 1800 to 2600°C.

[0043] The ReW bar that has completed the recrystallization treatment is subjected to the third rolling and striking process. The third rolling and striking process is preferably carried out at a heating temperature of 1200 to 1500°C. The area reduction rate per heat is preferably about 10 to 30%. The third rolling and striking process is carried out until the ReW bar has a diameter that can be drawn (preferably 2 to 4 mm).

[0044] After the third rolling process, the ReW rod material is subjected to a process of applying a lubricant to its surface and drying the lubricant to enable smooth wire drawing (DW) processing. The wire drawing process involves repeatedly applying the lubricant, drying the lubricant, heating to a processable temperature, and drawing using a drawing die. A carbon (C)-based lubricant with excellent heat resistance is preferably used. The processing temperature is set according to the wire diameter to be drawn. For example, the processing temperature is preferably 1100°C or lower. The area reduction rate per die is preferably 10 to 35%. During the wire drawing process, an annealing process or a surface polishing process (e.g., an electrolytic process) may be added under known conditions, as necessary.

[0045] The ReW wire that has completed the wire drawing process is polished. For example, the polishing process can be performed by electrochemical polishing (electrolytic polishing) in a sodium hydroxide solution with a concentration of 3 to 15 wt%. The area reduction rate in the polishing process is preferably 10 to 25%. If it is less than 10%, it may not be possible to remove the unevenness on the material surface that occurs during the rolling and wire drawing processes, and the mixture that adheres to the unevenness on the material surface. If the amount of surface removal is insufficient, a layer of the mixture may remain locally, which may increase the proportion of rhenium. If it exceeds 25%, the material yield will decrease.

[0046] In the case of electrolytic polishing, the polishing speed is preferably 0.5 to 3.0 μm / sec. If the polishing speed is slower than 0.5 μm / sec, the tungsten on the surface may be preferentially dissolved, increasing the proportion of rhenium on the surface. If the polishing speed exceeds 3.0 μm / sec, the amount of electrolysis per unit time increases, resulting in rapid electrolysis and the possibility of insufficient correction of the cross-sectional shape of the ReW wire. After electrolytic polishing, the ReW wire is washed to remove any alkali metals or carbon remaining on the surface. The washing water is preferably pure water with a conductivity of 1 μS / cm or less. Ultrasonic cleaning may also be used in combination.

[0047] After polishing, the ReW wire may be subjected to a drying process, for example. The drying process is carried out, for example, in a vacuum dryer with the temperature inside the dryer set to a range of 50 to 80°C. The drying time is, for example, one hour or more. After that, a predetermined shipping inspection is carried out. When storing the ReW wire after vacuum drying, it can be stored in a moisture-proof storage cabinet with a relative humidity of 5% or less to prevent moisture absorption. For example, except when conducting characteristic or quantity inspections, the ReW wire is stored in the moisture-proof storage cabinet.

[0048] The ReW wire is, for example, wound onto a shipping spool while undergoing a shipping inspection. After the shipping inspection, the outermost surface of the ReW wire wound onto the shipping spool is covered with protective paper and secured with a rubber band or the like. Then, the wire is placed in an aluminum bag together with an amount of ammonia adsorbent (e.g., mainly composed of SiO2) required to fit the capacity of the aluminum bag, and the bag is degassed to the extent that no tension is applied to the aluminum bag, and then sealed.

[0049] By using an appropriate amount of the ReW wire obtained in the above-mentioned process and carrying out the necessary processes under known conditions, a probe pin or medical needle with a specified wire diameter and the required properties (strength, hardness, etc.) can be obtained. Example 1 Doped tungsten powder with an average particle size of 13 μm and SD of 12 μm, containing potassium (K) in an amount that would result in a final wire of 50 wtppm to 80 wtppm, and rhenium powder with an average particle size of 6 μm and SD of 7 μm were mixed in an alcoholic solution to form a slurry with a rhenium content of 3 wt%. The resulting slurry was dried to produce the raw material powder.

[0050] The mixed powder of raw materials was press-molded to obtain a green body. The green body was subjected to preliminary sintering treatment at 1300°C in a hydrogen furnace. The green body was then sintered at 3000°C in a hydrogen atmosphere to obtain a sintered body. The sintered body was subjected to a first rolling process at a heating temperature of 1400°C, with a cross-sectional area reduction rate of 14% per heat treatment. The sintered body that had undergone the first rolling process was subjected to a second rolling process at a heating temperature of 1300°C, with a cross-sectional area reduction rate of 15% per heat treatment. After the second rolling process, the ReW rod was recrystallized in a hydrogen atmosphere at a temperature of 2400°C. After the recrystallization process, the third rolling process was carried out at a heating temperature of 1300°C, with a cross-sectional area reduction rate of 13% per heating process, to obtain a rod with a diameter of 2.5 mm. A lubricant was applied to the surface of the bar material that had been subjected to the third rolling process, and the bar material was then dried. The obtained bar material was then subjected to wire drawing. The wire drawing was performed at 1000°C, with the cross-sectional area reduction rate per drawing being 10% to 35%. The wire drawing process was followed by an annealing step at 1300°C. The drawn ReW wire was electropolished in an 8 wt% aqueous solution of sodium hydroxide. The electropolishing process was carried out with a cross-sectional area reduction rate of 15-20% and a polishing rate of 2.2 μm / sec. After electropolishing, the ReW wire was washed with pure water with a conductivity of 1 μS / cm. The resulting ReW wire had a diameter of 0.8 mm. After electropolishing, the ReW was dried for two hours in a vacuum dryer at 70°C, and then stored in a moisture-proof storage cabinet with a relative humidity of less than 5%. The resulting ReW wire was wound onto a shipping spool of 100m per spool, the outermost surface covered with protective paper, and secured with a rubber band. The shipping spool with the ReW wire wound on it was placed in an aluminum bag together with an ammonia adsorbent mainly composed of SiO2, and the bag was degassed to the extent that no tension was applied to the bag, and then sealed. Three similar spools were manufactured, and the three spool samples were lined up on a 1-meter-high stand in a room with a humidity of 60% or less and a room temperature of 30°C or less for 13 months. After 13 months, the occurrence of discoloration was confirmed using the method described above (the difference between the maximum and minimum reflectance values ​​in the wavelength range of 400 nm to 700 nm in the reflectance spectrum, as explained with reference to Figure 3).

[0051] Example 2 A ReW wire was produced in the same manner as in Example 1, except that the raw tungsten powder was not doped with potassium, the rhenium content was 26 wt%, and the final ReW wire diameter was 0.15 mm, and the wire was wound around a shipping spool of 500 m per spool and stored in an aluminum bag together with an ammonia adsorbent using the same packaging method as in Example 1. As in Example 1, three identical spools were produced and stored for 13 months using the same method as in Example 1, and after 13 months, the occurrence of discoloration was confirmed.

[0052] Example 3 A ReW wire was produced using the same raw material powder as in Example 1, and the same processes as in Example 1 were carried out up to the wiredrawing process. A ReW wire with a wire diameter of 0.8 mm was obtained using the same method as in Example 1, except that the obtained ReW wire was subjected to an electrolytic polishing process at a polishing rate of 4.0 μm / sec and was not stored in a moisture-proof storage cabinet after the electrolytic polishing process. The obtained ReW wire was wound on a shipping spool of 100 m / spool, the outermost surface was covered with protective paper, and the spool was secured with a rubber band. The shipping spool on which the ReW wire was wound was placed in an aluminum bag together with a desiccant containing silica gel, and the aluminum bag was vacuum-deaerated and sealed. Three identical spools were produced and stored for 13 months using the same method as in Example 1. After 13 months, the presence or absence of discoloration was confirmed.

[0053] (Comparative Example 2) A ReW wire was produced using the same raw material powder as in Example 2, and the same processes as in Example 2 were carried out up to the wiredrawing process. A ReW wire with a wire diameter of 0.15 mm was obtained in the same manner as in Example 2, except that the obtained ReW wire was subjected to an electrolytic polishing process at a polishing speed of 4.0 μm / sec and was not stored in a moisture-proof storage cabinet after the electrolytic polishing process. The obtained ReW wire was wound onto a shipping spool of 500 m per spool and packaged in the same manner as in Example 3. Three identical spools were produced and stored for 13 months in the same manner as in Example 1. After 13 months, the presence or absence of discoloration was confirmed.

[0054] Example 4 A ReW wire was manufactured in the same manner as in Example 2 and wound onto a shipping spool of 500 m per spool. The shipping spool of Example 4 was stored in an aluminum bag together with a desiccant containing silica gel, and the aluminum bag was vacuum-deaerated and sealed. Three identical spools were manufactured and stored for 13 months in the same manner as in Example 1. After 13 months, the presence or absence of discoloration was confirmed.

[0055] Table 3 shows the measurement results for the rhenium content, potassium content, and NH4 content. The rhenium and potassium contents were analyzed using inductively coupled plasma optical emission spectroscopy (ICP-OES). The lower detection limit for potassium is 5 wtppm, and values ​​below 5 wtppm without addition are indicated by "-". The NH4 content was measured by hot water extraction from 0.5 g of alloy wire in 50 ml of pure water using ion chromatography. The ICS-2000 analyzer manufactured by Thermo Fischer Scientific, Inc. was used.

[0056] [Table 3]

[0057] As can be seen from Table 3, the ReW wire according to the embodiment can suppress discoloration even during long-term storage, and can significantly improve yield when used as a probe pin or medical needle.

[0058] In Examples 1 to 4, in which at least one of the three spools had a NH₄ content of 10 mass ppm or less on the wire surface, discoloration after long-term storage was suppressed. In contrast, in Comparative Example 2, in which the NH₄ content of all three spools exceeded 10 mass ppm on the wire surface, discoloration occurred after long-term storage. While some variation in the moisture content or ammonia adsorption amount in the working environment from the electropolishing process to storage in the aluminum bag is unavoidable, it is presumed that Example 3 and Comparative Example 2 are susceptible to the variation in moisture content or ammonia adsorption amount. This is thought to be because, in Example 3 and Comparative Example 2, the electropolishing speed was set to 4.0 μm / sec, the wire was not stored in a moisture-proof storage cabinet, and no ammonia adsorbent was used.

[0059] Although several embodiments of the present invention have been described above, these embodiments are presented by way of example only and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. Modifications of these embodiments are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. Furthermore, the above-described embodiments can be implemented in combination with each other.

[0060] The following describes the invention in terms of embodiments.

[0061] <1> A tungsten rhenium alloy wire is a wire made of a tungsten alloy containing rhenium, and the amount of NH4 on the wire surface, calculated by the weight of NH4 ions on the wire surface / weight of the alloy wire, is 10 massppm or less. <2> The rhenium content is 2 wt% or more and less than 30 wt%; <1> The rhenium-tungsten alloy wire according to claim 1. <3> The rhenium content is 10 wt% or more and 28 wt% or less, <1> The rhenium-tungsten alloy wire according to claim 1. <4> The potassium (K) content is 30 wtppm or more and 90 wtppm or less. <1> Or <3> The tungsten rhenium alloy wire according to any one of claims 1 to 14. <5> The diameter is 0.1 mm or more and 1.00 mm or less, <1> Or <4> The tungsten rhenium alloy wire according to any one of claims 1 to 14. <6> Used as wire for medical needles, <1> Or <5> The tungsten rhenium alloy wire according to any one of claims 1 to 10. <7> Used as wire for probe pins, <1> Or <5> The tungsten rhenium alloy wire according to any one of claims 1 to 10. <8> <1> Or <7> 10. The method for producing a rhenium-tungsten alloy wire according to claim 1 . <9> <1> Or <5> A medical needle using the rhenium-tungsten alloy wire according to any one of claims 1 to 4. <10> <1> Or <5> A probe pin using the rhenium-tungsten alloy wire according to any one of claims 1 to 4. [Explanation of symbols]

[0062] A: Undiscolored area B: Discolored area X...Sample spool Y... Mesh base Z…Container A(CW)...Discolored sample B(NW)...No discoloration sample

Claims

1. A wire made of a tungsten alloy containing rhenium, and NH 4 NH on the wire surface, calculated by ion weight / alloy wire weight 4 A tungsten rhenium alloy wire having an amount of 10 mass ppm or less.

2. 2. The tungsten rhenium alloy wire according to claim 1, wherein the rhenium content is 2 wt% or more and less than 30 wt%.

3. 2. The tungsten rhenium alloy wire according to claim 1, wherein the rhenium content is 10 wt % or more and 28 wt % or less.

4. 2. The tungsten rhenium alloy wire according to claim 1, wherein the potassium (K) content is 30 wtppm or more and 90 wtppm or less.

5. 2. The tungsten rhenium alloy wire according to claim 1, wherein the diameter is 0.1 mm or more and 1.00 mm or less.

6. The tungsten rhenium alloy wire according to any one of claims 1 to 5, which is used as a wire material for medical needles.

7. The tungsten rhenium alloy wire according to any one of claims 1 to 5, which is used as a wire material for a probe pin.

8. 6. The method for producing a tungsten rhenium alloy wire according to claim 1.

9. A medical needle using the tungsten rhenium alloy wire according to any one of claims 1 to 5.

10. A probe pin using the tungsten rhenium alloy wire according to any one of claims 1 to 5.

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