Molybdenum mesh

Abstract

To provide a molybdenum mesh having a long life.SOLUTION: The molybdenum mesh 1 can be bent at room temperature even after recrystallization.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to molybdenum mesh. [Background technology]

[0002] Conventional molybdenum meshes are described, for example, in Japanese Patent Laid-Open Nos. 4-210834 (Patent Document 1) and 63-243249 (Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 4-210834 [Patent Document 2] Japanese Patent Publication No. 63-243249 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional molybdenum mesh has the problem of being easily broken. [Means for solving the problem]

[0005] The molybdenum mesh of the present disclosure is a molybdenum mesh that can be bent at room temperature even after recrystallization. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a plan view of a mesh structure 10 constituting a molybdenum mesh 1 according to the first embodiment. [Figure 2] FIG. 2 is an enlarged plan view of the area surrounded by II in FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4]FIG. 4 is a plan view of a mesh structure 10 constituting a molybdenum mesh 1 having folds according to the second embodiment. [Figure 5] FIG. 5 is a diagram for explaining a method for manufacturing the molybdenum mesh 1 according to the second embodiment. [Figure 6] FIG. 6 is a diagram illustrating a method for manufacturing the molybdenum mesh 1 according to the second embodiment. [Figure 7] FIG. 7 shows a molybdenum mesh 1 having an end portion 13 without a cut surface according to a third embodiment. [Figure 8] FIG. 8 is a photograph showing the cross-sectional structure of a pure molybdenum wire and a lanthanum-doped molybdenum wire before and after heat treatment. [Figure 9] FIG. 9 is a diagram showing a method for measuring the bending properties of the molybdenum mesh 1 at room temperature. [Figure 10] FIG. 10 shows a method for carrying out an impact test on the molybdenum mesh 1 at room temperature. DETAILED DESCRIPTION OF THE INVENTION

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

[0008] Conventionally, when a molybdenum mesh is baked, the molybdenum mesh becomes extremely embrittled when exposed to high temperatures during use, and is prone to breakage when handled at room temperature.

[0009] Recrystallized molybdenum mesh is prone to deformation due to grain boundary sliding at high temperatures depending on its crystal morphology, and at room temperature, the grain boundary strength decreases, making it prone to fracture due to recrystallization embrittlement when a bending load is applied.

[0010] Molybdenum mesh exposed to high temperatures during use where recrystallization may occur becomes significantly embrittled, and there is a problem in that it is prone to breakage when handled at room temperature.

[0011] Furthermore, there was a problem that the mesh would deform during use, and the shape would be transferred to the fired product. The short lifespan of the mesh and poor production efficiency were technical problems.

[0012] The molybdenum mesh in the present disclosure is a molybdenum mesh that can be bent at room temperature even after recrystallization.

[0013] The deformation amount is 5 mm or less when a creep test is carried out at 900°C. In the molybdenum mesh configured in this manner, the deformation amount (warpage) after the creep test can be kept to 5 mm or less, so that deformation of the molybdenum mesh during use can be suppressed.

[0014] Preferably, the molybdenum mesh has a folded portion at its end with a width of 100 to 300% of the thickness of the molybdenum mesh. In a molybdenum mesh configured in this manner, the thickness increases at the end, making it possible to increase the strength.

[0015] Preferably, the deformation during recrystallization is 1 mm or less by performing recrystallization heat treatment. Preferably, the molybdenum mesh contains 0.05% by mass to 2.00% by mass of lanthanum as unavoidable impurities, with the remainder being molybdenum. In the molybdenum mesh thus configured, the effect of lanthanum is to elongate the crystal grains, making it easier to exhibit desired properties.

[0016] Preferably, the molybdenum mesh for firing comprises any of the molybdenum meshes described above.

[0017] Preferably, the firing method uses the molybdenum mesh for firing described above. (Embodiment 1) Fig. 1 is a plan view of a mesh structure 10 constituting a molybdenum mesh 1 according to embodiment 1. As shown in Fig. 1, the molybdenum mesh 1 as a base plate has a mesh structure 10 containing molybdenum.

[0018] The mesh structure 10 is made of wires of molybdenum or molybdenum alloy.

[0019] The mesh structure 10 is formed by weaving or knitting the wires 11 and 12. The end faces of the wires 11 and 12 are cut surfaces 11e and 12e. The cut surfaces 11e and 12e are formed by cutting the wires 11 and 12.

[0020] Fig. 2 is an enlarged plan view showing the area surrounded by II in Fig. 1. As shown in Fig. 2, wires 11 and 12 intersect to form a mesh structure 10. A plurality of meshes 19 are formed by the intersection of wires 11 extending in the vertical direction and wires 12 extending in the horizontal direction.

[0021] In this embodiment, the wires 11 and 12 extend perpendicular to each other, but the wires 11 and 12 may also extend at an acute angle to each other.

[0022] Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2. As shown in Fig. 3, the cross section of wire rod 11 is round. The cross section of wire rod 11 may also be angular. Similarly, the cross section of wire rod 12 may also be round or angular.

[0023] The wire diameter of the wires 11 and 12 used in the molybdenum mesh 1 is preferably 0.1 mm or more and 1.0 mm or less. By setting the diameter within this range, the molybdenum mesh 1 becomes resistant to deformation at high temperatures and easy to process. If the diameter is less than 0.1 mm, the strength of the wires 11 and 12 may be insufficient for firing applications. If the diameter exceeds 1.0 mm, there is no problem, but the wires 11 and 12 will lack flexibility and will be difficult to weave.

[0024] The molybdenum mesh 1 is cut to the desired size using a shearing or slitter. Shearing makes the cut surface sharp, making the embrittlement of the molybdenum more likely to break or fall off, but bending part or all of it can prevent a decrease in strength and damage due to snagging during handling.

[0025] The bent section can be pressed to eliminate any unevenness and increase the loading area of ​​the sintered material. Alternatively, by making the thickness up to three times the mesh thickness, it can function as a spacer when stacked.

[0026] The wires 11 and 12 may contain 2.00 mass % or less of La oxide. Pure molybdenum embrittled by recrystallization has poor ductility when handled at room temperature, and may break due to stress during handling.

[0027] Adding La oxide increases the grain boundary strength and prevents breakage. The components are analyzed using inductively coupled plasma (ICP) emission spectroscopy.

[0028] Since deformation increases in the temperature range of 1500 to 2600°C, it is preferable to perform a recrystallization treatment. The recrystallization treatment is preferably performed after processing the molybdenum mesh 1. By removing processing strain in the woven mesh, deformation resistance can be improved.

[0029] If the molybdenum mesh 1 is deformed, the shape may be transferred to the sintered material. The present disclosure is expected to improve the quality and yield of the sintered material.

[0030] The mesh structure 10 is made of pure molybdenum or a molybdenum alloy. The pure molybdenum material used for the mesh structure 10 is preferably a molybdenum material with a general purity of 98.5% by mass or more. The molybdenum alloy may contain a metal additive in an amount of more than 0% but not more than 1.0% by mass. La oxide is preferred as the additive. The additive components are measured by inductively coupled plasma (ICP) optical emission spectroscopy. For ICP optical emission spectroscopy, an ICPS-8100 (Shimadzu Corporation) is used.

[0031] The mesh structure 10 contains inevitable impurities (e.g., Al, Ca, Fe, Mg, and Si). The inevitable impurities are determined in accordance with Section 7.4 (Inductively Coupled Plasma (ICP) Optical Emission Spectroscopy: Fe Measurement) of (JIS H 1404 2001), the method for quantifying nonvolatile matter (JIS H 1404 2001), etc. For the ICP method, an ICPS-8100 (Shimadzu Corporation) is used.

[0032] The shape of the mesh structure 10 may be other than a rectangle. The molybdenum mesh 1 may be woven by any method.

[0033] (Embodiment 2) FIG. 4 shows a molybdenum mesh 1 having folds according to the second embodiment. 1 is a plan view of a mesh structure 10. Folded portions 21 and 22 are provided at end portions 13, 14, 15 and 16 of a mesh structure 10 according to a second embodiment.

[0034] The end surfaces of the wires 11 and 12 are cut surfaces 11e and 12e. The cut surfaces 11e and 12e are formed by cutting the wires 11 and 12. The mesh structure 10 shown in FIG. 1 is formed by bending each side of a molybdenum mesh 1 made of an octagonal molybdenum alloy wire with the corners of the square rounded off. Therefore, the folded portions do not overlap at the corners. However, this structure does not necessarily have to be adopted, and the mesh structure 10 may also be formed by folding each side of a mesh of a square molybdenum alloy wire. In this case, the corners of the mesh structure 10 have a structure in which four layers of mesh are overlapped.

[0035] Fig. 5 is a diagram for explaining a method for manufacturing the molybdenum mesh 1 according to the second embodiment. Fig. 6 is a diagram for explaining a method for manufacturing the molybdenum mesh 1 according to the second embodiment.

[0036] 5, to manufacture the molybdenum mesh 1, first, the end 13 of the mesh structure 10 is bent as shown by the arrow 101. In this embodiment, the end 13 is bent upward, but the end 13 may also be bent downward.

[0037] 6, the folded portion 21 is formed by pressing the vicinity of the end portion 13 in the direction indicated by the arrow 102. The thickness of the folded portion 21 is reduced by pressing.

[0038] 7 is a diagram showing a molybdenum mesh 1 having an end portion 13 without a cut surface according to a third embodiment. As shown in FIG. 7, there is also a molybdenum mesh 1 having an end portion 13 without a cut surface. In this case, the wires 12 are woven at the end portion 13, and the molybdenum mesh 1 can be formed without cutting the wires 12. The end portion 13 without a cut surface does not need to be folded back if it has sufficient strength.

[0039] The thickness of the mesh structure 10 is measured using a digital micrometer with a diameter D of 6 mm and a flat anvil and spindle measuring surface. The thickness can also be measured using a vernier caliper.

[0040] When the number of sides with folded portions is one or more, the average value of the thicknesses of the folded portions is taken as the thickness of the folded portions. The thickness is measured at the center of the mesh structure 10 and taken as the thickness of the molybdenum mesh 1. The thickness of the folded portions is preferably 100% or more and 300% or less of the thickness of the molybdenum mesh 1.

[0041] (Example) The present disclosure will be described below based on examples.

[0042] (1) Manufacturing of molybdenum mesh (1-1) Manufacturing of molybdenum wire Metal powders with various molybdenum and lanthanum compositions were prepared as shown in Tables 1 and 2. The Fe content in the metal powder was 0.01 mass % or less, and the non-volatile content was 0.02 mass % or less.

[0043] [Table 1]

[0044] [Table 2]

[0045] Sample numbers 1 to 14 in Table 1 have the same composition as sample numbers 1a to 14a in Table 2. The difference is whether or not a recrystallization heat treatment is performed in the subsequent step.

[0046] This was pressed and sintered by a molybdenum wire processing method to produce an ingot. The obtained ingot was subjected to grooved roll rolling or swaging, and then wiredrawing to obtain molybdenum wires of sample numbers 1 to 14 and 1a to 14a having the diameters shown in the "Wire diameter" column in Tables 1 and 2. The molybdenum wires were electrolytically polished, annealed, and finally finished.

[0047] (1-2) Woven net, cutting process Molybdenum wire samples 1 to 14 and 1a to 14a were used to stretch a warp thread with a width of 1100 mm on a loom. The weft thread was set perpendicular to the warp thread and woven with a reed to produce a 35 m long roll. The roll was cut into a width of 220 mm and a length of 180 mm using a shearing or slitter.

[0048] (1-3) Bending process For sample numbers 4, 11 to 14, 4a, and 11a to 14a, the ends of two or four sides were bent by 5 mm to 20 mm using a press brake.

[0049] After bending, the mesh was pressed to a thickness of up to three times the mesh thickness, thereby obtaining the molybdenum mesh 1 shown in FIG. 1 or FIG.

[0050] (1-4) Recrystallization heat treatment Using a baking furnace, the material was recrystallized by heating it in a vacuum atmosphere at the temperature of "recrystallization heat treatment" shown in Table 2. Specifically, the temperature was increased at a rate of 10°C / min up to the recrystallization heat treatment temperature in Table 2. The recrystallization heat treatment time in Table 2 was maintained, and the temperature was lowered to room temperature at a rate of 20°C / min.

[0051] This recrystallization heat treatment is not performed on the samples in Table 1. A jig may be used to increase the processing volume, but it is preferable to use a jig made of the same material as the molybdenum mesh 1 to avoid reactions at the contact points between the molybdenum mesh 1 and the jig.

[0052] That is, the molybdenum mesh 1 was heated to 1200°C or higher, at which recrystallization begins, to elongate the crystal grains in the longitudinal direction of the wire. The recrystallization heat treatment temperature is preferably 1500°C or higher and 2000°C or lower. Treatment below the recrystallization temperature may not be effective enough. Temperatures above 2000°C are not a problem, but may increase costs and cause reactions at the contact points. The recrystallization heat treatment time is the time required for the molybdenum constituting the molybdenum mesh 1 to be sufficiently recrystallized. However, longer recrystallization heat treatment times are less economical.

[0053] In addition to a vacuum atmosphere, the firing furnace may be in a reducing gas atmosphere such as hydrogen, or an inert gas atmosphere. In Tables 1 and 2, the "Temperature (°C)" in the "Heat Treatment" column refers to the maximum temperature during the heat treatment, and the "Time (H)" refers to the time the maximum temperature was maintained.

[0054] After the recrystallization heat treatment, the mesh of the molybdenum mesh 1 was unraveled, embedded in resin, and polished to a mirror finish approximately halfway down the unraveled line. Crystal observation was then performed using an appropriate etching solution such as Murakami's reagent.

[0055] Crystal observations were performed using a Keyence VHX-1000 digital microscope at magnifications of approximately 50 to 400 times, depending on wire diameter and other conditions, and confirmed that the structure had changed from a fibrous structure after plastic processing to a recrystallized structure due to heat treatment. In Tables 1 and 2, "fibrous" refers to the structure after plastic processing (wiredrawing). "Coarse" or "long" refers to the structure after recrystallization. "Coarse" refers to isotropic crystal growth, and "long" refers to anisotropic crystal growth (Figure 8).

[0056] Figure 8 is a photograph showing the cross-sectional structure of a pure molybdenum wire and a lanthanum-doped molybdenum wire before and after heat treatment. Figure 8 shows the structure before and after heat treatment. From Figure 8, it can be seen that the structure has become coarse or elongated.

[0057] When pure molybdenum is subjected to recrystallization heat treatment, the fibrous structure that is observed after plastic working becomes coarse.

[0058] After recrystallization, the composition of Molybdenum Mesh 1 was confirmed to be consistent with that of the raw material. Furthermore, the wire diameters of Molybdenum Mesh 1 were confirmed to be consistent with those in Table 2.

[0059] In Tables 1 and 2, "folds (sides)" refers to the number of folded sides in the molybdenum mesh 1, and "folds (number of times)" refers to the number of times a folded side is folded.

[0060] (2) Evaluation of molybdenum mesh The molybdenum mesh was evaluated by bending test, impact test, and creep test. Tables 3 and 4 show the evaluation results of the molybdenum mesh 1 prepared in Tables 1 and 2, respectively, with and without recrystallization heat treatment (Table 4 and Table 3, respectively).

[0061] [Table 3]

[0062] [Table 4]

[0063] (2-1) Evaluation 1: Bending test 9 is a diagram showing a method for measuring the bending properties of molybdenum mesh 1 at room temperature. A bending test was carried out on molybdenum mesh 1. Molybdenum mesh 1 (sample number 12a) and, for comparison, pure molybdenum mesh 1 (sample number 4a) were tested.

[0064] For the evaluation, a wire diameter of 0.35 mm and #24 mesh were used, with the four edges folded 5 mm apart. #24 mesh means that there are 24 wires in a width of 1 inch (25.4 mm). The mesh size of the molybdenum mesh 1 is preferably #4 to 50 mesh.

[0065] The folded portions 21 and 22 were pressed to a thickness that was 115% of the thickness of the unfolded portion. The size of the molybdenum mesh 1 was a square with a width L of 50 mm and a length B of 50 mm. Both ends of the molybdenum mesh 1 were supported by stands 115 and 116 at 10 mm, with a φ5 round bar 112 serving as a bridge in the center. The distance between the stands 115 and 116 was 30 mm.

[0066] The round bar 112 is connected to a tension gauge 110 by a wire 113. At room temperature, a concentrated load was applied to the molybdenum mesh 1 by pulling the tension gauge 110 downward as indicated by an arrow 111. The load was gradually increased, and the maximum load at which the mesh broke or plastically deformed was measured with the tension gauge to confirm whether or not breakage occurred.

[0067] Measurements were taken in both the warp and weft directions, and the average value was used for evaluation. Pure molybdenum easily broke when the load was increased to 2.2 kgf (2.2 x 9.8 N). On the other hand, the mesh containing La oxide did not break even when a load of 6 kgf was applied, and instead underwent plastic deformation at 90°.

[0068] When the same test was performed on the other sample numbers, the molybdenum meshes of sample numbers 5a to 14a did not break even when a load of 6 kgf was applied, and instead underwent plastic deformation at 90°.

[0069] Similar tests were also carried out on other sample numbers. The results are shown in the "Bending Test" column in Tables 3 and 4.

[0070] In the "Bending test" column, an evaluation of "A" indicates that the molybdenum mesh 1 did not break at any location even when a load of 6 kgf was applied. A "B" indicates that the molybdenum mesh 1 broke at any location when a load of less than 6 kgf was applied.

[0071] From this test, it can be said that sample numbers 5 to 14 (5a to 14a) are molybdenum meshes 1 that can be bent at room temperature even after recrystallization. Note that none of sample numbers 1 to 14 (Table 3) in Table 1 that were not subjected to recrystallization heat treatment broke.

[0072] (2-2) Evaluation 2: Impact test A destructive test (impact resistance test) was carried out on the molybdenum mesh 1. The molybdenum mesh 1 (sample number 5a) and, for comparison, the pure molybdenum mesh 1 (sample number 1a) were tested.

[0073] FIG. 10 shows a method for conducting an impact test of a molybdenum mesh 1 at room temperature. A #24 mesh with a wire diameter of 0.35 mm was used for the evaluation, and the size of the molybdenum mesh 1 was a square with a width L of 100 mm and a length B of 100 mm. The molybdenum mesh 1 was placed on a frame with a width of 50 mm and a length of 50 mm. This created a hole 130, shown by the dotted line in FIG. 10. The hole 130 is an area where no frame exists. The molybdenum mesh 1 is placed above the hole 130, covering it. The dimensions of the hole 130 were 50 mm wide and 50 mm long. m. The inside of the hole 130 is not supported by the frame. Therefore, when force is applied to the hole 130 from above, the molybdenum mesh 1 that constitutes the hole 130 is deformed. In contrast, the outside of the hole 130 is in direct contact with the frame, so even if force is applied from above to the outside of the hole, the molybdenum mesh 1 is not deformed.

[0074] At room temperature, a cylindrical weight 131 weighing 130 grams was dropped freely from a height of 100 mm onto a hole 130 located at the center of the molybdenum mesh 1 .

[0075] The test was repeated five times. With pure molybdenum, the impact load caused tears and breakage in the molybdenum mesh 1. However, the molybdenum mesh 1 containing La oxide only deformed and did not tear.

[0076] Similar tests were also carried out on other sample numbers. The results are shown in the "Impact Test" column in Tables 3 and 4.

[0077] The samples in Table 3 that had not undergone recrystallization heat treatment only deformed, and no breakage occurred.

[0078] "A" indicates that no breakage occurred in the molybdenum mesh 1 even after five repeated tests. "B" indicates that breakage occurred in the molybdenum mesh 1 at least once out of five repeated tests. From this test, it can be said that sample numbers 5a to 14a are molybdenum mesh 1 that will not break in an impact test at room temperature after recrystallization.

[0079] (2-3) Evaluation 3: Creep test Creep tests were conducted on molybdenum mesh 1. Molybdenum mesh 1 (sample No. 5) and pure molybdenum mesh 1 (sample No. 1) were fabricated for comparison. For evaluation, a 0.35 mm wire diameter #24 mesh was used. Molybdenum mesh 1 was rectangular, 50 mm wide and 100 mm long. Molybdenum mesh 1 was supported at both ends by 10 mm, and a 131 g cylindrical weight was placed in the center. It was heated to 900°C in a hydrogen atmosphere using a kiln, and the treatment was repeated three times. With the weight attached, the height of the center of the span was measured with a digital caliper. The difference before and after heat treatment was taken as the deformation amount. Pure molybdenum mesh 1 exhibited a deformation of 6.8 mm, while molybdenum mesh 1 containing La oxide exhibited a deformation of only 3.8 mm.

[0080] Similar tests were conducted on other sample numbers. The results are shown in the "Creep deformation" column in Tables 1 and 2.

[0081] The creep deformation of specimens 1a to 4a, which do not contain lanthanum, was large, but the creep deformation of specimen 4a was small due to the folding action.

[0082] In sample number 1-14, which was not subjected to recrystallization heat treatment, the amount of creep deformation was larger than in sample numbers 1a-14a, which were subjected to recrystallization heat treatment. However, in sample numbers 5-14 and 5a-14a, the creep deformation was small due to the effect of additives. In sample numbers 4, 11-14, 4a, and 11a-14a, the creep deformation was small due to the folding action. The recrystallization heat treatment temperature is 1800°C. The small creep deformation amount makes it possible to provide a molybdenum mesh 1 that can withstand long-term use. (Appendix 1) Molybdenum mesh that can be bent at room temperature even after recrystallization. (Appendix 2) Lanthanum is 0.05% to 2.00% by mass, and contains unavoidable impurities, with the remainder being molybdenum. 10. A molybdenum mesh as described in Appendix 1, comprising molybdenum. (Appendix 3) 3. The molybdenum mesh according to claim 1, wherein the molybdenum mesh has an end folded back with a width that is 100 to 300% of the thickness of the molybdenum mesh. (Appendix 4) 4. The molybdenum mesh according to any one of claims 1 to 3, wherein the deformation amount when subjected to a creep test at 900°C is 5 mm or less. (Appendix 5) 5. The molybdenum mesh according to any one of claims 1 to 4, wherein the molybdenum mesh is subjected to a recrystallization heat treatment so that the deformation amount is 1 mm or less when subjected to a creep test at 900°C. (Appendix 6) 6. A molybdenum mesh for firing according to any one of claims 1 to 5. (Appendix 7) A firing method using the molybdenum mesh for firing described in Appendix 6.

[0083] 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]

[0084] 1 Molybdenum mesh, 10 Mesh structure, 11, 12 Wire rod, 11e, 12e Cutting surface, 13,14,15,16 End, 19 Eye, 21,22 Folded part, 101,102,111 Arrow, 110 Tension gauge, 112 Tip, 115,116 Base, 130 Hole, 131 Weight.

Claims

1. Molybdenum mesh that can be bent at room temperature even after recrystallization.

2. 2. The molybdenum mesh according to claim 1, containing lanthanum in an amount of 0.05% by mass to 2.00% by mass and unavoidable impurities, with the remainder being molybdenum.

3. 3. The molybdenum mesh according to claim 1, wherein the ends of the molybdenum mesh are folded back to a width that is 100 to 300% of the thickness of the molybdenum mesh.

4. 3. The molybdenum mesh according to claim 1, wherein the amount of deformation when subjected to a creep test at 900°C is 5 mm or less.

5. 3. The molybdenum mesh according to claim 1, which has been subjected to a recrystallization heat treatment so that the deformation amount when subjected to a creep test at 900°C is 1 mm or less.

6. 3. The molybdenum mesh for firing according to claim 1 or 2.

7. A firing method using the molybdenum mesh for firing according to claim 6.

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