Tungsten-containing wire

Abstract

This wire including tungsten comprises 50-150 ppm of at least one selected from the group consisting of potassium, cerium, lanthanum, and silicon, wherein the wire has a tungsten content of 99.92 mass% or more, a wire diameter of 5-22 µm, and a surface roughness Ra of 0.5 µm or less.

Description

[Technical Field]

[0001] This disclosure relates to wires containing tungsten. This application claims priority to Japanese Patent Application No. 2020-013619, filed on January 30, 2020, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] Conventionally, a wire containing tungsten is disclosed in, for example, Japanese Patent Laid-Open No. 2018-1434 (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-1434 A Summary of the Invention

[0004] The tungsten-containing wire of the present disclosure contains at least one selected from the group consisting of potassium, cerium, lanthanum, and silicon in an amount of 50 ppm or more and 150 ppm or less, has a tungsten content of 99.92 mass% or more, has a wire diameter of 5 μm or more and 22 μm or less, and has a surface roughness Ra of 0.5 μm or less. [Brief explanation of the drawings]

[0005] [Figure 1] FIG. 1 is a perspective view of a line 10 for explaining measurement points. DETAILED DESCRIPTION OF THE INVENTION

[0006] [Problem to be solved by this disclosure] Conventional tungsten-containing wires have the problem of low tensile strength.

[0007] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described.

[0008] Conventionally, when mesh is made using ultra-fine pure tungsten wires, frequent wire breakage during the mesh making process has been a technical problem. The reason for this is thought to be that pure tungsten with a surface roughness of Ra 0.1 μm or more has low wire strength and high friction, which causes frequent wire breakage during mesh making.

[0009] In contrast, the tungsten-containing wire of the present disclosure contains at least one element selected from the group consisting of potassium (K), cerium (Ce), lanthanum (La), and silicon (Si) in an amount of 50 ppm or more and 150 ppm or less, has a tungsten content of 99.92 mass% or more, has a wire diameter of 5 μm or more and 22 μm or less, and has a surface roughness Ra of 0.5 μm or less.

[0010] [composition] In the composition of the wire containing tungsten, the first additive (at least one selected from K, Ce, La, and Si) is 50 ppm or more and 150 ppm or less by mass ratio. In this specification, "ppm" refers to ppm by mass ratio.

[0011] Preferably, the content of the first additive is 60 ppm or more and 125 ppm or less, and more preferably 70 ppm or more and 100 ppm or less. By setting it in this range, extremely high strength can be achieved even if the surface roughness is Ra 0.1 μm or more.

[0012] If the content of the first additive is less than 50 ppm, the tensile strength decreases. If the content of the first additive is more than 150 ppm, the possibility of wire breakage due to a decrease in purity increases. The first additive increases the strength of the wire containing tungsten.

[0013] The content of second additives (Mo, Re, Zr) is 0 ppm to 100 ppm below It is preferable that the second additive is small in amount and does not adversely affect the wire containing tungsten. The second additive may not be included.

[0014] The content of unavoidable impurity elements is 10 ppm or more and 550 ppm or less. Theoretically, the content of impurity elements is preferably 0 ppm or more. However, it is difficult to reduce the impurity content to less than 10 ppm from a production technology perspective. Therefore, the impurity content is preferably 10 ppm or more. If the impurity element content is greater than 550 ppm, the possibility of wire breakage increases. The content of impurity elements is preferably 250 ppm or less, and more preferably 100 ppm or less.

[0015] The tungsten-containing wire may include a first dopant, a second dopant, and unavoidable impurities, with the remainder being tungsten.

[0016] Regarding the method for measuring the composition of the first and second additives, the K, Ce, La, Si, Mo, Re, and Zr in the W alloy of the final sintered product were measured by the ICP method using an ICPS-8100 model (manufactured by Shimadzu Corporation).

[0017] The unavoidable impurities were Al, Ca, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sn, Na, O, C, and N. Al, Ca, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sn, and Na were measured by ICP using an ICPS-8100 (Shimadzu Corporation). N and O were measured by inert gas fusion / infrared absorption and thermal conductivity methods using an ON386 (LECO).

[0018] C was measured by infrared absorption method using WC230 (LECO). The tungsten content was obtained in accordance with the analytical method for tungsten materials (JIS H1403 2011), and excludes the values of Al, Ca, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sn, Na, O, C, N (these are called impurities) and primary and secondary additives.

[0019] The tungsten content is preferably 99.92 mass% or more, more preferably 99.95 mass% or more, and even more preferably 99.98 mass% or more.

[0020] [Surface roughness] The surface roughness of the wire is Ra 0.5 μm or less. The surface roughness Ra is preferably greater than 0.05 μm, and more preferably greater than 0.1 μm. From the perspective of preventing wire breakage when using wires containing tungsten, a smaller Ra is better, but achieving a surface roughness Ra of 0.1 μm or less is costly. A surface roughness greater than 0.5 μm is not practical because wire breakage occurs significantly.

[0021] The surface roughness of the wire was measured using a measuring device (a laser microscope manufactured by KEYENCE) and the Ra of the measurement point (wire end) was measured at three points: the tip 11, the center 12, and the rear end 13 of the wire 10 as shown in Figure 1, and the average was calculated. The measurement device's setting parameters were: measurement length: 7 μm (for a wire diameter of φ8 μm), cutoff value: 1.5 (for a wire diameter of φ8 μm). Spherical correction was performed to optimize the cutoff value for each wire diameter. If the wire diameter φ was 5 μm, the cutoff value was set to 1.0. If the wire diameter φ was 12 μm, the cutoff value was set to 2.4. If the wire diameter φ was 22 μm, the cutoff value was set to 4.4.

[0022] Wire diameter The wire diameter is 5 μm or more and 22 μm or less. By making the wire diameter 22 μm or less, it can be used in applications where stainless steel wire does not have the strength to withstand. With the current level of technology, it is difficult to make the wire diameter less than 5 μm.

[0023] The wire diameter was measured using a measuring device (microelectronic balance) to measure the diameter at three measurement points (wire ends) and average the results.

[0024] [Tensile strength] Tensile strength is 4000N / mm 2 More than 4500N / mm 2 It is preferable that:

[0025] Tensile strength: 4000N / mm 2 The higher the tensile strength, the better.2 The above is difficult to manufacture.

[0026] The tensile strength was measured using a measuring device (tensile tester), with three tensile test pieces approximately 250 mm long cut from the measurement point (wire end), and the tensile strength of each piece measured and averaged. The measuring device parameters were set to a gauge length of 200 mm and a measurement speed of 50 mm / min.

[0027] The tungsten-containing wire of the present disclosure can be used as a lamp filament, a cut wire for wire electrical discharge machining, a mesh for screen printing, and the like.

[0028] [Details of the embodiments of the present disclosure] (Example) In the examples, wires containing tungsten were fabricated and evaluated.

[0029] [Table 1]

[0030] [Table 2]

[0031] [Table 3]

[0032] Manufacturing of tungsten alloy wire (The following shows the manufacturing method of sample number 10. For manufacturing conditions of other samples, see Tables 1 to 3) 1. Weighing and mixing 150 kg of tungsten powder (W powder) (average particle size 4 μm) and 230 g of potassium chloride powder (K powder) were weighed out. The weighed powders were placed in a mixer and mixed in an air atmosphere for 120 minutes. The weighed values for each sample number are shown in Tables 1 to 3. La, Ce, and Si in sample numbers 24 to 32 were supplied from La2O3 (lanthanum oxide), CeO2 (cerium oxide), and SiO2 (silicon oxide).

[0033] 2. Press 680 tons (6.7 x 10 6 N) Using a press, 2.5 kg of mixed powder was added and the pressure was 140 kg / cm 2 The dimensions of the pressed body are 15 x 17 x 900 mm.

[0034] 3. Sintering Using a direct sintering furnace in which an electric current is directly applied to the pressed body (green compact), sintering was carried out at a current value of 1800 A in a hydrogen atmosphere for 1 minute, thereby obtaining a sintered body.

[0035] 4. Swage Using a swaging device, the sintered body was heated with a burner and swaged until it became φ3.7 mm. During the process, it was annealed in a hydrogen atmosphere in a heat treatment furnace. This resulted in a linear body.

[0036] 5.Wire drawing processing Using a wire drawing machine, the filamentous body was heated with a burner and drawn until the wire diameter D was 16 μm, with a wire diameter reduction of 10% per die drawing ((wire diameter before processing - wire diameter after processing) / wire diameter before processing). This resulted in a tungsten-containing wire. The reduction and wire diameter after drawing for each sample number are shown in Tables 1 to 3.

[0037] 6.Electrolytic polishing Electrolytic polishing was performed using an electrolytic device under the processing conditions (speed 60 m / min, concentration of electrolyte (caustic potash) 24% by volume). The voltage was adjusted while observing the wire diameter at a constant speed. The weight value of each sample number and The rates and electrolyte concentrations are shown in Tables 1 to 3.

[0038] 7. Evaluation of tungsten alloy wire The tensile strength of each sample number was evaluated using the methods described above in the sections on [Composition], [Surface roughness], [Wire diameter], and [Tensile strength]. The results are shown in Tables 4 to 6.

[0039] [Table 4]

[0040] [Table 5]

[0041] [Table 6]

[0042] From Tables 4 to 6, it can be seen that the tensile strength values deteriorate when the potassium content is less than 50 ppm and more than 150 ppm, so the potassium content must be between 50 ppm and 150 ppm.

[0043] When the potassium content was between 60 ppm and 125 ppm, particularly excellent values were obtained in tensile strength.

[0044] The best tensile strength was obtained when the potassium content was between 70 ppm and 100 ppm.

[0045] The embodiments and examples disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0046] 10 lines, 11 tips, 12 middles, 13 backs.

Claims

1. A tungsten-containing wire containing at least one element selected from the group consisting of potassium, cerium, lanthanum, and silicon in an amount of 50 mass ppm or more and 150 mass ppm or less, a tungsten content of 99.92 mass % or more, unavoidable impurities of 10 mass ppm or more and 550 mass ppm or less, a wire diameter of 5 μm or more and 22 μm or less, a surface roughness Ra of 0.5 μm or less, and a tensile strength of 4000 N / mm 2 or more.

2. A wire containing tungsten, the wire containing at least one element selected from the group consisting of potassium, cerium, lanthanum, and silicon in an amount of 50 mass ppm or more and 150 mass ppm or less, the tungsten content being 99.92 mass % or more, the contents of second additives molybdenum, rhenium, and zirconium being more than 0 mass ppm and not more than 100 ppm, the unavoidable impurities being 10 mass ppm or more and 550 mass ppm or less, the wire diameter being 5 μm or more and 22 μm or less, the surface roughness Ra being 0.5 μm or less, and the tensile strength being 4000 N / mm 2 or more.

3. 3. The tungsten-containing wire according to claim 1 or 2, containing at least one selected from the group consisting of potassium, cerium, lanthanum, and silicon in an amount of 60 ppm by mass or more and 125 ppm by mass or less.

4. The tungsten-containing wire according to claim 3, containing at least one selected from the group consisting of potassium, cerium, lanthanum, and silicon in an amount of 70 ppm by mass or more and 100 ppm by mass or less.

5. A wire containing tungsten described in any one of claims 1 to 4, used in a mesh for screen printing.

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