Flaky titanium porous body and manufacturing method and application thereof

Abstract

Disclosed is a sheet-like titanium porous body. The sheet-like titanium porous body has a thickness of 40 [mu] m or more and 500 [mu] m or less and a porosity of 30% or more and 50% or less. The surface roughness of the first main surface of the sheet-shaped porous titanium body is lower than the surface roughness of the second main surface facing the first main surface. The number of first protrusions protruding from the first main surface at a height of 30 [mu] m or more is equal to or less than the number of second protrusions protruding from the second main surface at the peripheral edge of the sheet-shaped porous titanium body at a height of 30 [mu] m or more.

Description

Technical Field

[0001] One embodiment of the present invention relates to a sheet-like porous titanium body, a method for manufacturing the same and its application, and a fixture for implementing the manufacturing method. Background Technology

[0002] Plate-like porous metals containing metal (zero-valent metal) are widely used in filters, secondary battery electrodes, current collectors in polymer electrolyte fuel cells, catalyst supports, etc. Depending on their intended use, these plate-like porous metals can be processed using lasers, blades, etc. (see Patent Documents 1 and 2). Patent Document 1 discloses a pair of opposing blades capable of cutting long plate-like porous metals extending in a specific direction. Patent Document 2 discloses a method of laser-cutting a plate-like porous metal and an adjacent layer into a laminate, where the sides of the plate-like porous metal and the adjacent layer join together at the laser-cut point, thus forming the laminate. In this method, due to the strong bonding between the plate-like porous metal and the adjacent layer, icicle-like burrs are formed at the laser-cut point, exhibiting an anchoring effect. In other words, it can be described as a cutting method that actively forms burrs.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2020 / 039693

[0006] Patent Document 2: Japanese Patent Application Publication No. 2011-106023 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] One embodiment of the present invention provides a sheet-like porous metal containing titanium, namely, a sheet-like porous titanium body and its applications. Alternatively, one embodiment of the present invention provides a method for manufacturing sheet-like porous titanium bodies with high efficiency and high yield, and a fixture for implementing the method.

[0009] Solution for solving the problem

[0010] One embodiment of the present invention is a sheet-like porous titanium body. The sheet-like porous titanium body has a thickness of 40 μm or more and 500 μm or less, and a porosity of 30% or more and 50% or less. The surface roughness of the first principal surface of the sheet-like porous titanium body is lower than the surface roughness of the second principal surface opposite to the first principal surface. At the periphery of the sheet-like porous titanium body, the number of first protrusions with a height of 30 μm or more protruding from the first principal surface side is less than the number of second protrusions with a height of 30 μm or more protruding from the second principal surface side at the periphery.

[0011] One of the embodiments of the present invention is the application of the sheet-like porous titanium body as a porous transport layer in a polymer electrolyte membrane-type water electrolysis device.

[0012] One of the embodiments of the present invention is a method for preparing hydrogen in a polymer electrolyte membrane water electrolysis device using the aforementioned sheet-like porous titanium body.

[0013] One embodiment of the present invention relates to a method for manufacturing a sheet-like porous titanium body. The method includes: arranging a mother sheet containing the porous titanium body on a fixture to cover at least one through-hole and a gap between at least one stage and a frame, wherein the fixture includes at least one stage having at least one through-hole, a frame surrounding and separate from the at least one stage, and at least one connecting portion connecting the at least one stage and the frame; adsorbing the mother sheet onto the fixture; and cutting the mother sheet by scanning a laser emitted from a fiber laser along the gap onto the mother sheet.

[0014] One embodiment of the present invention is a fixture for manufacturing sheet-like porous titanium bodies. The fixture includes: at least one stage having at least one through hole; a frame surrounding and separate from the at least one stage; and at least one connecting portion connecting the at least one stage and the frame to each other. Attached Figure Description

[0015] Figure 1 This is a schematic diagram illustrating a method for manufacturing a sheet-like porous titanium body according to one embodiment of the present invention.

[0016] Figure 2A This is a schematic top view of a clamp according to one embodiment of the present invention.

[0017] Figure 2B This is a schematic side view of a clamp according to one embodiment of the present invention.

[0018] Figure 3A This is a schematic cross-sectional view of a fixture according to one embodiment of the present invention.

[0019] Figure 3B This is a schematic cross-sectional view of a fixture according to one embodiment of the present invention.

[0020] Figure 3C This is a schematic cross-sectional view of a fixture according to one embodiment of the present invention.

[0021] Figure 3D This is a schematic cross-sectional view of a fixture according to one embodiment of the present invention.

[0022] Figure 4AThis is a side view of a clamp according to one of the embodiments of the present invention.

[0023] Figure 4B This is a schematic top view of the airflow adjustment table of the fixture used in one embodiment of the present invention.

[0024] Figure 5A A schematic top view illustrating a method for manufacturing a sheet-like porous titanium body according to one embodiment of the present invention.

[0025] Figure 5B A schematic cross-sectional view illustrating a method for manufacturing a sheet-like porous titanium body according to one embodiment of the present invention.

[0026] Figure 6A A schematic cross-sectional view illustrating a method for manufacturing a sheet-like porous titanium body according to one embodiment of the present invention.

[0027] Figure 6B A schematic top view illustrating a method for manufacturing a sheet-like porous titanium body according to one embodiment of the present invention.

[0028] Figure 7 This is a schematic top view of a clamp according to one embodiment of the present invention.

[0029] Figure 8A This is a schematic perspective view of a sheet-like porous titanium body according to one embodiment of the present invention.

[0030] Figure 8B This is a schematic side view of a sheet-like porous titanium body according to one embodiment of the present invention.

[0031] Figure 9A This is a schematic perspective view of a sheet-like porous titanium body according to one embodiment of the present invention.

[0032] Figure 9B This is a schematic side view of a sheet-like porous titanium body according to one embodiment of the present invention.

[0033] Figure 10A A photograph of the master film manufactured in the embodiment.

[0034] Figure 10B This is a photograph of the sheet-like porous titanium body manufactured in the embodiments. Detailed Implementation

[0035] In the following description, a method for manufacturing a sheet-like porous titanium body according to embodiments of the present invention, and a sheet-like porous titanium body manufactured according to the method, will be described with reference to the accompanying drawings and other materials. However, the present invention can be implemented in various ways without departing from its spirit and is not limited to the description of the embodiments illustrated below.

[0036] To make the description clearer, the accompanying drawings may schematically represent the width, thickness, shape, etc. of various parts compared to the actual embodiment, but are merely examples and do not limit the interpretation of the invention. In this specification and the various drawings, elements having the same function as those described with respect to the figures already presented may be denoted by the same reference numerals, and repeated descriptions may be omitted.

[0037] 1. Method for manufacturing sheet-like porous titanium bodies

[0038] The following describes a method for manufacturing a sheet-like porous titanium body according to one embodiment of the present invention. Porous titanium bodies possess high liquid permeability and high air permeability, electrical conductivity, and excellent corrosion resistance, and are therefore used as electrode materials and filters that can be used in highly corrosive environments. In particular, sheet-like porous titanium bodies with a thickness of tens to hundreds of μm can be used as porous transport layers (PTLs) in polymer electrolyte membrane (PEM) type water electrolysis devices.

[0039] In this manufacturing method, a large-sized sheet-like titanium porous body with an area larger than the final manufactured sheet-like titanium porous body is produced. This sheet-like titanium porous body is then appropriately cut to produce a sheet-like titanium porous body with the desired size and shape. This large-sized sheet-like titanium porous body will be referred to as the master sheet below.

[0040] The master sheet and the sheet-like porous titanium are composed of pure titanium, essentially also referred to as industrial pure titanium, with a purity equivalent to pure titanium types 1 to 4 in JIS H4600 (2012), typically type 1 to 2. More specifically, the titanium content in the master sheet and the sheet-like porous titanium is 97% by mass or more, or 98% by mass or more. The upper limit for titanium content is 99.8% by mass or less, or 99% by mass or less. The titanium content is obtained by subtracting the total content of metallic components other than titanium and non-metallic components such as oxygen from 100% by mass. Furthermore, depending on the manufacturing conditions of the sheet-like porous titanium, the oxygen content may be higher than that of industrial pure titanium. For example, the sheet-like porous titanium produced by the paste process described later often has a higher oxygen content compared to the dry process.

[0041] (1) Manufacturing of master film

[0042] There are no restrictions on the method of preparing the master sheet; it can be prepared using either a dry process or a paste process. In the dry process, for example, titanium microparticles or titanium fibers with a purity of 99% or higher are deposited on a mold setter, then scraped into a thin sheet shape, and then heated and sintered at a high temperature (e.g., above 950°C) to obtain the master sheet. In this case, to facilitate separation from the mold setter, it is best to coat the mold setter with a release agent such as boron nitride or titanium boride, and then deposit titanium microparticles or titanium fibers on it. Furthermore, the titanium microparticles can be spherical, but by using shapes deviating from spherical shapes, such as titanium microparticles manufactured by hydrogenation dehydrogenation (HDH powder), the number of bonding points between the titanium microparticles increases. As a result, a master sheet with a three-dimensional network structure containing numerous fine pores can be obtained. When using titanium microparticles, a master sheet with a sponge-like three-dimensional network structure can be obtained. On the other hand, when using titanium fibers, a master sheet with a nonwoven fabric-like three-dimensional network structure can be obtained.

[0043] In the paste-making process, a paste containing titanium microparticles or fibers, a binder, and a solvent is first prepared. Binders include cellulose, polyvinyl alcohol resin, acrylic resin, and polyvinyl butyral resin. Solvents include alcohols such as ethanol and isopropanol, aromatic solvents such as toluene and xylene, hydrocarbons such as cyclohexane, and ketones such as methyl ethyl ketone. The paste may also contain additives such as defoamers, dispersants, leveling agents, and plasticizers. However, it is best to avoid using foaming agents and water. Figure 1 As shown, paste 134 is applied onto substrate 150 and the solvent is evaporated at room temperature or under heating conditions (e.g., 80°C to 160°C) to obtain sheet-like preform 136.

[0044] The blank 136 is peeled from the substrate and placed on the shaping device 152, which serves as a support substrate. Preferably, the blank 136 is arranged such that the surface 136a of the blank 136 that contacts the substrate 150 is on the opposite side of the shaping device 152 (see reference). Figure 1 Then, degreasing is performed by heating the preform 136 placed on the setter 152 in an oxygen-containing atmosphere such as air. For example, degreasing is performed by heating at a temperature of 300°C or higher and 450°C or lower for 3 hours or more and 20 hours or less. As a result, the binder and additives are pyrolyzed or volatilized to obtain a sheet-like brown body 138 that is essentially composed of titanium.

[0045] Furthermore, after debinding, the brown body 138 arranged on the setter 152 is sintered at a high temperature of approximately 750°C to 1100°C to obtain the master sheet 130. Even using the paste method, a master sheet 130 with a sponge-like or non-woven fabric-like three-dimensional network structure can be obtained, similar to the dry method. When the paste does not contain water and foaming agent, the surface smoothness of the manufactured master sheet 130 tends to be excellent. In particular, the surface roughness of the surface 130a of the master sheet 130 (hereinafter referred to as the surface for convenience) 130a, which is the surface 136a of the blank 136 that contacts the substrate 150, is smaller than that of the surface opposite to the surface 130a (hereinafter referred to as the back side for convenience). For example, the maximum height Rz, which is an indicator related to the surface roughness of the surface 130a, is 1.0 μm or more and 10 μm or less, or 1.0 μm or more and 7 μm or less, or 1.0 μm or more and 5 μm or less. On the other hand, the maximum height Rz of the back side 130b is greater than the maximum height Rz of the surface side, and for example, exceeds 10 μm. The maximum height Rz of the surface side can be calculated according to ISO (International Organization for Standardization) 4287-1997.

[0046] The size of the master sheet 130 is not limited and can be larger than the final manufactured titanium porous body. For example, the master sheet 130 can have a quadrilateral shape with one side being 200 mm or more and 2000 mm or less. The thickness of the master sheet 130 can also be arbitrarily determined, for example, it can be selected from the range of 10 μm or more and 3000 μm or less, 40 μm or more and 1000 μm or less, or 40 μm or more and 500 μm or less, typically 40 μm or more and 300 μm or less. The porosity of the master sheet 130 is also not limited, but is preferably 30% or more and 50% or less. Smooth-surfaced sheet-like titanium porous bodies tend to have lower porosity to some extent. Furthermore, in the unit of a (PEM) type water electrolysis device, the ion exchange membrane and the sheet-like titanium porous body are sometimes arranged in a pressed state. If the surface of the sheet-like titanium porous body is smooth, damage to the ion exchange membrane can be effectively suppressed.

[0047] (2) Cut the mother sheet

[0048] The method for cutting the mother sheet 130 will be described below. The sheet-like porous titanium body is manufactured by properly cutting the mother sheet 130 using a jig described in detail below.

[0049] A. Fixture

[0050] A schematic top view of fixture 100 is shown below. Figure 2A As shown, along Figure 2A The schematic diagrams of the cross sections of the dashed lines A-A', B-B', and C-C' in the diagram are shown below. Figures 3A to 3C As shown. Figure 2AAs shown, the clamp 100 includes at least one stage 104 and a frame 102 surrounding the stage 104. Figure 2B As shown, the suction stage 110 is arranged below the clamp 100. The thickness of the stage 104 and the frame 102 can be appropriately determined according to their dimensions, for example, more than 1 mm and less than 10 mm.

[0051] The stage 104 and the frame 102 are not in direct contact and are separate from each other. However, the stage 104 and the frame 102 are connected by at least one connecting part 106. Therefore, a gap (groove) 108 is formed between the stage 104 and the frame 102 (see reference). Figure 2A and Figure 3B As described later, a laser irradiates the master sheet 130, which is arranged to overlap with the gap 108, along the gap 108, thereby cutting the master sheet 130 and cutting out the sheet-like porous titanium body. Therefore, the shape of the gap 108 essentially determines the shape of the sheet-like porous titanium body. The shape of the gap 108 is determined by the outer peripheral shape of the stage 104. In other words, the outer peripheral shape of the stage 104 can be appropriately selected according to the shape of the sheet-like porous titanium body to be manufactured; for example, it can be a polygon including quadrilaterals, a circle or an ellipse, or a shape defined by a contour consisting of curves and straight lines.

[0052] The stage 104, frame 102, and connector 106 comprise, for example, metal. Preferably, the stage 104, frame 102, and connector 106 all contain titanium, more preferably made of 99% by mass or more titanium, i.e., industrially pure titanium. Because the stage 104, frame 102, and connector 106 comprise high-purity titanium, contamination during the cutting of the master sheet 130 can be prevented. As a result, impurities can be prevented from entering the porous sheet-like titanium.

[0053] Alternatively, at least one of the stage 104, frame 102, and connecting part 106 may comprise resin or wood. Examples of resins include polypropylene, polycarbonate, acrylic resin, polyetheretherketone, polytetrafluoroethylene, polyamide, polyacetal, modified polyphenylene ether, polybutylene terephthalate, polyphenylene sulfide, and other engineering plastics. By using resin or wood, the weight of the clamp 100 can be reduced.

[0054] like Figures 2A to 3CAs shown, at least one through-hole 104a is provided on the stage 104 in a direction perpendicular to its upper surface. The at least one through-hole 104a may include multiple through-holes 104a. The multiple through-holes 104a are preferably arranged at a uniform density, i.e., at a constant spacing. The spacing of the through-holes 104a can, for example, be set in the range of 30 mm or more and 70 mm or less. The shape of the through-hole 104a (the shape on the upper surface of the stage 104) is, for example, circular or polygonal. In the latter case, each corner can be rounded. The size of the at least one through-hole 104a can also be appropriately determined. For example, if the through-hole 104a is circular, its diameter can be appropriately selected from the range of 10 mm or more and 30 mm or less. In the case where the through-hole 104a is polygonal, its area can be equal to the area of ​​the circular through-hole 104a described above. The multiple through-holes 104a can be arranged in a matrix and can be arranged to occupy the vertices of the honeycomb structure.

[0055] As described above, the frame 102 surrounds the stage 104. Therefore, the shape of the inner periphery of the frame (the outline of the stage 104 side on the upper surface of the frame 102) is substantially similar to the shape of the outer periphery of the stage 104. The inner periphery shape of the frame 102 is preferably set such that the width of the gap 108 between the frame 102 and the stage 104 is more than 1 mm and less than 10 mm, and is generally preferably more than 3 mm and less than 6 mm. As described later, the mother sheet 130 is attached to the frame 102 and the stage 104 in a state of being arranged to cover the gap 108. However, since the gap 108 has a width within the above-described range, the deflection of the mother sheet 130 on the gap 108 can be suppressed, thereby enabling precise cutting.

[0056] At least one connecting portion 106 connecting the stage 104 and the frame 102 may include a plurality of connecting portions 106. The connecting portions 106 are provided to partition a portion of the gap 108. Therefore, the number of connecting portions 106 is typically the same as the number of gaps 108. The positions of the connecting portions 106 can be suitably determined to maintain a stable positional relationship between the stage 104 and the frame 102. Preferably, a pair of connecting portions 106 are provided on the clamp 100 to hold the stage 104. Furthermore, as... Figure 2AAs shown, multiple pairs of connecting portions 106, which clamp the stage 104, can be provided in intersecting directions. The connecting portions 106 connect the stage 104 and the frame 102, fixing the positional relationship between them. That is, the shape of the gap 108, which essentially determines the shape of the sheet-like porous body obtained by cutting the master sheet 130, can be fixed. As a result, sheet-like porous bodies with a specific shape can be efficiently mass-produced. The width of the connecting portion 106 (its length in the direction perpendicular to the sides of the stage 104 and the frame 102) corresponds to the width of the gap 108. Therefore, the width of the connecting portion is set to be 1 mm or more and 10 mm or less, and typically 3 mm or more and 6 mm or less. Generally, when cutting sheet-like porous metal bodies, protrusions known as burrs are sometimes generated on the cut surface (protrusions that protrude from the periphery toward one side of the main surface, but the main surface opposite to the direction of protrusion is flat or substantially flat). However, from the viewpoint of suppressing the generation of burrs on sheet-like porous titanium bodies during cutting, the length of the connecting portion 106 (the length in the extension direction of the gap 108 separated by the connecting portion 106) is preferably short to a certain extent, for example, 0.5 mm or more and 50 mm or less.

[0057] The thickness of the connecting portion 106 (its length in the direction of extension of the through hole 104a) can be the same as the thickness of the stage 104 or the frame 102, or it can be less than the thickness of the stage 104 or the frame 102, such as... Figure 3D As shown in the diagram. In the first case, the upper surface of the connecting portion 106 is on the same plane as the upper surfaces of the stage 104 and the frame 102. In the second case, the height of the upper surface of the connecting portion 106 is lower than the upper surface of the stage 104 or the frame 102. In other words, the upper surface of the connecting portion 106 is located on the lower surface side of the stage 104 and the frame 102 compared to the upper surface of the stage 104 or the frame 102. By setting the height of the upper surface of the connecting portion 106 to be lower than the upper surface of the stage 104 or the frame 102, contact between the connecting portion 106 and the mother plate 130 can be prevented, and as a result, the generation of burrs can be more effectively suppressed. Although not shown, the lower surface of the connecting portion 106 can be located on the upper surface side of the stage 104 and the frame 102 compared to the lower surface of the stage 104 or the frame 102.

[0058] The suction table 110 is connected to an exhaust device (not shown) and is configured to generate a negative pressure on the suction table 110. As described later, during cutting, the mother sheet 130 is arranged on the clamp 100. Therefore, by using the exhaust device, the gas present in the through hole 104a and gap 108 of the clamp 100 is drawn away via the suction table 110 (see reference). Figure 2B (As shown by the arrow in the image), the mother sheet 130 was attracted to the fixture 100.

[0059] like Figure 4A As shown, the airflow regulating table 120 can be arranged between the clamp 100 and the suction table 110. Alternatively, the suction table 110 can be integrated with the airflow regulating table 120. Figure 4B The diagram schematically illustrates that the airflow regulating table 120 is a support platform, smaller in shape than the through-hole 104a of the stage 104, and has more through-holes 120a than the through-hole 104a. The through-holes 120a extend in a direction perpendicular to the upper surface of the airflow regulating table 120. While the shape (shape on the upper surface of the airflow regulating table 120) and arrangement of the through-holes 120a are not limited, it is preferable to arrange the hexagonal through-holes 120a in a honeycomb pattern to allow for a high-density arrangement. By providing the airflow regulating table 120, the airflow generated by the suction table 110 can be made uniform, thereby allowing the master sheet 130 to be adsorbed onto the clamp 100 with uniform force across the entire master sheet 130.

[0060] B. Cutting the master sheet

[0061] use Figures 5A to 6B This describes the process of cutting the mother piece 130 using a fixture 100. Figure 5A It corresponds to Figure 2A A schematic top view, and Figure 5B and Figure 6A It corresponds to Figure 3A A schematic cross-sectional view.

[0062] First, place the master film 130 on the fixture 100. At this point, as... Figure 5A and Figure 5B As shown, the mother plate 130 is arranged on the fixture 100 in such a way that it completely overlaps with all the through holes 104a and gaps 108. At this time, the mother plate 130 is arranged on the fixture 100 such that its back surface 130b contacts the stage 104. In addition, the mother plate 130 is arranged to cover the entirety or at least a portion of the frame 102. Therefore, all the through holes 104a and gaps 108 are covered by the mother plate 130.

[0063] Then, begin suction using the exhaust device (see reference). Figure 5B (Solid arrow in the image). When suction begins via suction stage 110, the gas in through hole 104a and gap 108 is drawn directly or via airflow regulating stage 120 to suction stage 110 (see reference). Figure 5B (The dashed arrow in the image). As a result, a negative pressure is generated in the through hole 104a and the gap 108, and the mother piece 130 is adsorbed and fixed to the fixture 100.

[0064] Next, a fiber laser is used to cut the master wafer 130. Specifically, as shown... Figure 6AAs shown, a laser 140 emitted from a fiber laser irradiates the mother plate 130 from the side opposite to the clamp 100. That is, the laser 140 irradiates from the surface 130a side. A fiber laser is a solid-state laser that uses optical fiber as the amplification medium. For example, a rare-earth element such as ytterbium is doped into the core at the center of the fiber to form one or more cladding layers with a refractive index lower than the core surrounding the core. The wavelength of the laser is, for example, 1000 nm or more and 1200 nm or less, and its output is, for example, adjusted to 50 W or more and 800 W or less. The laser is pulsed, and its pulse frequency can be appropriately selected from the range of 400 Hz or more and 1200 Hz or less. The laser irradiates such that its focus is located on or near the surface of the mother plate 130 (e.g., within ±5 mm of the surface). The diameter of the laser beam on the mother plate 130 is adjusted to 40 μm or more and 200 μm or less. The laser scanning speed can be appropriately adjusted according to the thickness and number of sheets of the master film 130, for example, it can be above 1000 mm / min and below 10000 mm / min. Furthermore, when the laser irradiates, the entire or part of the environment used for cutting the master film 130 is set to an inert gas atmosphere, such as nitrogen or argon. Preferably, an argon atmosphere is used to prevent discoloration of the cut surface due to nitriding. For example, in an atmospheric environment, an inert gas can be sprayed as a protective gas onto the laser irradiation location. Alternatively, the entire fixture 100 can be arranged in an inert gas atmosphere and irradiated with the laser. Therefore, laser scanning can be performed in an inert gas environment, and oxidation and nitriding of the master film 130, as well as the resulting contamination and discoloration, can be suppressed.

[0065] The laser scans along gap 108 on the mother plate 130. This is achieved by scanning the laser along gap 108 and the connecting portion 106 from the initial irradiation position, and then re-irradiating the initial position. Figure 6B As shown, the mother plate 130 is cut along the laser scanning path 142, and a sheet-like porous titanium body 132 with a shape reflecting the gap 108 can be cut out. When the upper surface of the connecting part 106 is on the same plane as the upper surface of the stage 104 or the frame 102, the laser irradiates the mother plate 130 in contact with the connecting part 106, but damage to the connecting part 106 is prevented by setting the laser output and / or scanning speed within the aforementioned range. Therefore, the fixture 100 can be reused.

[0066] Under laser irradiation, the scanning direction bends by 90° at the corner of gap 108. At this point, the laser can be irradiated, causing the laser scanning path to be arc-shaped at the corner of gap 108. Therefore, the corners of the sheet-like porous titanium body 132 can be chamfered, thereby obtaining a sheet-like porous titanium body 132 with arc-shaped corners. Figure 6B The chamfer radius r can also be set arbitrarily. For example, the chamfer radius r can be set appropriately within the range of 1mm to 15mm.

[0067] The water jet method is a well-known method for cutting sheet-like porous metal bodies. However, because the water jet method uses abrasives, if post-cutting cleaning is insufficient, abrasive residue can remain on the sheet-like titanium porous body. Furthermore, when using a carbon dioxide laser to cut sheet-like porous metal bodies, it is difficult to avoid burrs during the melting and solidification process of the cut surface. Typically, burrs with a height (or length) of less than 100 μm can be physically removed using a scraper, but larger burrs are difficult to remove. Large burrs on the cut surface can affect the properties of the sheet-like porous metal body and the characteristics and reliability of various devices using it. For example, when sheet-like titanium porous bodies are used as the porous transport layer in a PEM-type water electrolysis device, they may induce damage to adjacent ion exchange membranes.

[0068] On the other hand, as described above, in the method for manufacturing a sheet-like porous titanium body according to one embodiment of the present invention, the mother sheet 130 is adsorbed onto the fixture 100, and a laser is scanned along the narrow gap 108 between the stage 104 and the frame 102 constituting the fixture 100 to cut the mother sheet 130. Therefore, the mother sheet 130 can be cut while fixed to the fixture 100, and the mother sheet 130 will not bend significantly in the gap 108. Therefore, the mother sheet 130 can be precisely cut, and a sheet-like porous titanium body 132 with an arbitrary shape can be manufactured.

[0069] Furthermore, since a laser-cut master sheet 130 is used, sheet-like porous titanium bodies 132 can be cut in a short time of approximately tens of seconds, and cleaning and drying steps can be eliminated or simplified, thus reducing workload. Moreover, as shown in this embodiment, the use of a fiber laser effectively suppresses burr formation and prevents the generation of burrs that could affect the properties of the sheet-like porous titanium body 132 and the properties of devices using the titanium porous body. These features contribute to improving the manufacturing efficiency and yield of sheet-like porous titanium bodies.

[0070] C. Variations

[0071] In the aforementioned fixture 100, a stage 104 is surrounded by a frame 102. The structure of the fixture 100 is not limited to this, such as... Figure 7 As shown, the clamp 100 may also have a plurality of stages 104 and a frame 102 surrounding the stages. Each of the stages 104 is secured to the frame 102 by at least one connecting portion 106, preferably one or more pairs of connecting portions 106. The number of stages 104 provided in a clamp 100 is not limited, for example, it can be suitably determined to be in the range of more than 2 and less than 20. Figure 7In the example shown, three stages 104-1, 104-2 and 104-3 are surrounded by a frame 102, and a gap 108 is formed between each stage 104 and the frame 102.

[0072] When using this fixture 100, multiple master sheets 130 can be arranged and cut simultaneously. Alternatively, a single master sheet 130 can be configured to cover all stages 104 and gaps 108, and then multiple sheet-like porous titanium bodies 132 can be manufactured from the single master sheet 130 by laser scanning along the gaps 108. Typically, manufacturing a single master sheet 130 takes several hours to several days; therefore, when manufacturing a single sheet-like porous titanium body 132 from a single master sheet 130, the manufacturing time for each sheet-like porous titanium body 132 is relatively increased. In contrast, by manufacturing a large master sheet 130 from which multiple sheet-like porous titanium bodies 132 are cut, the manufacturing time for each sheet-like porous titanium body 132 can be significantly reduced. Therefore, by applying one embodiment of the present invention, sheet-like porous titanium bodies 132 can be provided at low cost.

[0073] 2. Characteristics of sheet-like porous titanium bodies

[0074] The properties of the sheet-like porous titanium body 132 manufactured according to the above manufacturing method will be described below.

[0075] As described above, a sheet-like porous titanium body 132 is manufactured by cutting a mother sheet 130 using a laser 140 emitted from a fiber laser. Therefore, the composition, thickness, and porosity of the sheet-like porous titanium body 132 are identical to those of the mother sheet 130. The composition can be obtained by subtracting the content of metallic and non-metallic elements other than titanium from the total amount (100%) of the sheet-like porous titanium body 132. For example, the content of metallic elements other than titanium can be measured using high-frequency inductively coupled plasma (ICP) emission spectroscopy. The contents of non-metallic elements such as chlorine, oxygen, carbon, nitrogen, and hydrogen can be determined using silver nitrate titration, inert gas melting-infrared absorption, high-frequency combustion-infrared absorption, inert gas melting-thermal conductivity, and inert gas melting-thermal conductivity methods, respectively. The thickness can be measured using a thickness gauge, and the porosity can be calculated using the apparent density calculated based on the volume and mass of the object, and the true density of titanium.

[0076] Furthermore, unlike the sheet-like titanium porous body obtained by water jet cutting of the mother sheet 130, the sheet-like titanium porous body 132 manufactured by the above method does not contain components from the abrasive. Specifically, it does not contain particles containing inorganic compounds used as abrasives, such as silicon oxide, ferric oxide, aluminum oxide, magnesium oxide, calcium oxide, and manganese oxide. For example, the waste liquid discharged by cleaning the sheet-like titanium porous body 132 with water or the like does not contain particles constituting the abrasive. Therefore, even when using the sheet-like titanium porous body 132 in a PEM-type water electrolysis device, the dissolution of metal ions contained in the abrasive can be ignored, and contamination, deterioration, and damage to the PEM-type water electrolysis device caused by these metal ions can be prevented.

[0077] Due to the aforementioned cutting steps, the structure of the peripheral portion of the sheet-like porous titanium body 132 differs from that of the original sheet 130 before cutting. Specifically, the peripheral portion of the sheet-like porous titanium body 132 has a smaller deflection. For example... Figure 8A and Figure 8B As shown, the peripheral portion of the sintered mother sheet 130 may be bent due to deflection. Specifically, a protrusion 146 protruding into one surface of the peripheral portion and a recess 148 existing in a position corresponding to the protrusion 146 and recessed in another surface may appear. The height of the bent portion, i.e., the height h1 of the protrusion 146 (the height of the protrusion 146 relative to the flat portion of the surface on the side where the protrusion 146 exists), is about 1 mm to 2 mm. However, since the peripheral portion that may be bent can be removed by cutting the mother sheet 130 (see...), Figure 6B ), so as Figure 8B As shown, the peripheral portion of the sheet-like titanium porous body 132 has no bends, or even if there are bends, their height is extremely small (e.g., less than 0.1 mm).

[0078] Furthermore, although the sheet-like porous titanium body 132 is obtained by cutting the mother sheet 130, the burrs in the peripheral portion are very small, and their size (height) is also very small. Specifically, as... Figure 9A and Figure 9B As shown, to the surface 130a of the mother plate 130 (refer to) Figure 1The number of burrs 144 protruding from the surface (hereinafter referred to as the first main surface) 132a side of the sheet-like porous titanium body 132, with a height h2 (the height of the burr 144 based on the flat portion of the first main surface 132a) of 30 μm or more, is less than the number of burrs 144 protruding from the surface (hereinafter referred to as the second main surface) 132b side of the sheet-like porous titanium body 132 from the back surface 130b. There are no burrs 144 protruding towards the first main surface 132a side (i.e., the probability of the presence of burrs 144 of any length of peripheral portion is 0), or the probability of presence is less than 0.1 per 100 mm of peripheral portion. Therefore, the process of physically removing the burrs 144 protruding towards the first main surface 132a side can be omitted. As described above, the smoothness of the surface 130a of the master sheet 130 manufactured using the paste method is higher than that of the back surface 130b. Therefore, the first main surface 132a of the sheet-like porous titanium body 132 is not only highly smooth but also has few burrs, so even when pressed on the ion exchange membrane of the PEM-type water electrolysis device, the ion exchange membrane is not easily damaged.

[0079] Furthermore, the number of burrs 144 protruding towards the second main surface 132b is extremely small, with a length of 0.0 to 3.0 per 100 mm at the periphery. In addition, the height of the burrs 144 protruding towards the first main surface 132a or the second main surface 132b is also suppressed, with a maximum height of 100 μm or less. That is, there are no burrs exceeding 100 μm. Therefore, even if burrs 144 occur, almost all of them can be physically removed using a scraper or similar tool. Furthermore, even if burrs 144 are present, they do not protrude in a direction parallel to the first main surface 132a or the second main surface 132b. That is, it is difficult to produce burrs 144 with a thicker root width compared to the tip. This is believed to be because, unlike methods that use tools to cut the mother sheet 130 to create the sheet-like porous titanium body 132, the mother sheet 130 does not bear shearing force. As shown in this embodiment, this effect of suppressing burr 144 formation is due to the use of a laser emitted from a fiber laser to cut the mother sheet 130. Since there are no root-thick burrs 144 in the direction parallel to the first main surface 132a or the second main surface 132b, it is possible to prevent the sheet-like titanium porous body 132 from being dug up and damaged during the burr removal operation.

[0080] As described above, the peripheral portion of the sheet-like porous titanium body 132 has few burrs 144, and in particular, there are no or virtually no burrs 144 protruding towards the first main surface 132a. Therefore, by configuring structures (e.g., ion exchange membranes, etc.) used in the PEM-type water electrolysis device in contact with the sheet-like porous titanium body 132, damage to these structures can be effectively prevented. This greatly improves the service life and reliability of the PEM-type water electrolysis device.

[0081] In addition, to improve the operating efficiency of PEM-type water electrolysis devices, a coating is sometimes applied to the surface of the sheet-like porous titanium body, so that the coated sheet-like porous titanium body comes into contact with ion exchange membranes or the like. This coating is usually a thin film, and even after coating, the surface of the sheet-like porous titanium body 132 remains smooth. Therefore, when the coated sheet-like porous titanium body comes into contact with ion exchange membranes or the like, it can be considered that the sheet-like porous titanium body is in contact with ion exchange membranes or the like.

[0082] The shape of the master sheet 130 is essentially determined by the step of coating a paste containing titanium microparticles or titanium fibers onto the substrate 150. Therefore, it is difficult to precisely control the shape of the corners of the master sheet 130, and the corners have complex shapes composed of one or more straight lines and / or one or more curves. However, as described above, by scanning a laser in a manner that traces an arc during the stage of forming the corners of the sheet-like porous titanium body 132 in the process of cutting the master sheet 130, it is possible to form an arc-shaped chamfer at the corners of the sheet-like porous titanium body 132. Therefore, even if the corners of the sheet-like porous titanium body 132 are subjected to external force, damage to the sheet-like porous titanium body 132 can be prevented, and damage to other structures in contact with the corners of the sheet-like porous titanium body 132 can also be prevented.

[0083] 3. Applications of sheet-like porous titanium bodies

[0084] To reiterate, the sheet-like porous titanium body 132 involved in one embodiment of the present invention can preferably be used in a PEM-type water electrolysis device, and is particularly suitable as a porous transport layer. Therefore, one embodiment of the present invention uses the sheet-like porous titanium body 132 as a porous transport layer in a polymer electrolyte membrane-type water electrolysis device. In this case, it is preferable to arrange the sheet-like porous titanium body 132 such that a structure (e.g., an ion exchange membrane) in contact with the first main surface 132a of the sheet-like porous titanium body 132. However, the uses of the sheet-like porous titanium body 132 are not limited to this; it can be used in various applications and devices, such as various filters, electrode components for batteries, carriers for supporting catalysts, various composite materials, etc. Furthermore, using the sheet-like porous titanium body 132 in a PEM-type water electrolysis device to produce hydrogen and oxygen is also one embodiment of the present invention.

[0085] Example

[0086] 1. Example 1

[0087] A master sheet, consisting of sintered titanium microparticles with a thickness ranging from 160 μm to 170 μm and a porosity of approximately 40%, was fabricated using a paste-making method. The master sheet measures 400 mm × 500 mm. This master sheet was arranged on... Figure 2AThe fixture 100 shown is positioned such that it overlaps entirely with the stage 104 and the gap 108, and also partially overlaps with the frame 102. The stage 104, frame 102, and connecting portion 106 are all made of pure titanium equivalent to JIS Type 1. The upper surface of the stage 104 has a shape of 100mm × 200mm, and the gap 108 has a width of 3mm. The stage 104 and frame 102 have a thickness of 1.5mm. Next, the master sheet is adsorbed onto the fixture 100 using a suction table 110 via an aluminum airflow regulating table 120.

[0088] In this state, a fiber laser (manufactured by AMADA Corporation, model PRELAS1212AJ) with a wavelength in the range of 1050 nm to 1100 nm (output 180 W, laser diameter 40 μm, pulse frequency 600 Hz) was used to irradiate the mother sheet along the gap 108 in a straight section at a scanning speed of 5000 mm / min. Nitrogen gas was supplied as a protective gas to the laser irradiation site simultaneously with the laser irradiation. As a result, the mother sheet could be cut in approximately 15 seconds. Upon observation of the cut surface, no burrs exceeding 10 μm in height from the surface were observed. When the mother sheet was cut using argon gas as a protective gas, no burrs exceeding 10 μm in height from the surface were observed, and no discoloration was observed at the periphery of the resulting sheet-like porous body.

[0089] The photographs of the master sheet and the sheet-like porous titanium bodies obtained by cutting the master sheet are as follows: Figure 10A and Figure 10B As shown. From Figure 10A It is understood that before cutting, a portion of the periphery of the mother sheet undergoes flexing, with a height of approximately 1 mm to 2 mm. On the other hand, by removing the flexed portion caused by cutting, a sheet-like porous titanium body with an entirely flexed periphery can be obtained. Furthermore, applying pressure or heating to the flexed mother sheet may cause it to crack or reduce its porosity. Therefore, it is understood that by applying embodiments of the present invention, a sheet-like porous titanium body can be obtained whose periphery does not flex, without causing damage to the mother sheet or a reduction in its properties.

[0090] 2. Example 2

[0091] use Figure 3DThe fixture 100 shown is used to cut the mother sheet in the same manner as in Example 1. The height difference between the upper surface of the connecting portion 106 and the upper surface of the stage 104 is 1 mm. That is, the thickness of the connecting portion 106 is 0.5 mm. Using argon as a protective gas, the mother sheet was cut in the same manner as in Example 1. As a result, no burrs with a maximum height exceeding 10 μm from the surface were observed, and no discoloration was observed at the periphery of the resulting sheet-like porous body. In addition, in Example 1, some burrs with a maximum height less than 10 μm from the surface were sometimes generated at the location where the connecting portion 106 contacts the mother sheet, but in Example 2, it was confirmed that the generation of such small burrs could be basically completely prevented.

[0092] 3. Comparative Examples

[0093] As a comparative example, a laser emitted from a carbon dioxide laser (manufactured by AMADA Corporation, model FO-MII2412NT) was used to cut the mother sheet using the same method as in Examples 1 and 2. The laser wavelength was 11 μm, the laser diameter was 150 μm, and the laser scanning speed for the linear portion was set to 5000 mm / min. Nitrogen gas was used as the protective gas. The results showed that the mother sheet could be cut in approximately 15 seconds. However, burrs with a maximum height of 170 μm from the surface were observed at the periphery of the resulting sheet-like porous titanium body.

[0094] 4. Example 3

[0095] In this embodiment, the results of cutting a master sheet produced in a different batch than that of Example 1 will be described. The manufacturing and cutting methods of the master sheet are the same as those of Example 1, but the shape of the upper surface of the stage 104 is 50 mm × 70 mm. The side surface 240 mm of the two sheet-like porous titanium bodies (hereinafter referred to as samples A and B) obtained were observed using an optical microscope, and the number and height of burrs were measured. The results are shown in Table 1.

[0096] [Table 1]

[0097]

[0098] As shown in Table 1, burrs with a height of 30 μm or more are extremely rare. Furthermore, none were observed on the first main surface 132a (refer to Table 1). Figure 9AThe results confirm that the probability of burrs protruding more than 30 μm on the first main surface 132a side is 0, and the probability of burrs protruding more than 30 μm on the second main surface 132b side is less than 3.0 μm in length per 100 mm of perimeter. These results show that by applying the embodiments of the present invention, the generation of burrs can be effectively suppressed, and the generation of burrs protruding on one side (here, the first main surface 132a) can be completely prevented. In addition, the burrs generated on the second main surface 132b side of samples A and B can be easily removed using a titanium scraper. By removing the burrs, a sheet-like porous titanium body without burrs on the first main surface 132a side and the second main surface 132b side is obtained.

[0099] The above results demonstrate that by applying one embodiment of the present invention, the master sheet can be cut in a short time while suppressing burr formation, and a sheet-like porous titanium body with an arbitrary shape can be effectively provided. Furthermore, although burrs smaller than approximately 100 μm can be easily removed, physically removing burrs exceeding 100 μm in height results in the removal of not only the burrs but also their surrounding portions. Therefore, it can be said that, according to embodiments of the present invention, a sheet-like porous titanium body completely free of burrs and possessing the desired planar shape can also be manufactured.

[0100] Based on the embodiments described above as implementations of the present invention, any appropriate additions or deletions of constituent elements or design changes, or additions or omissions of processes or conditions made by those skilled in the art, as long as they capture the essence of the present invention, are included within the scope of the present invention. Even if there are other effects different from the above embodiments, effects that are obvious from the description in this specification or effects that can be easily predicted by those skilled in the art can of course be understood as effects brought about by the present invention.

[0101] Explanation of reference numerals in the attached figures

[0102] 100: Fixture, 102: Frame, 104: Stage, 104-1: Stage, 104-2: Stage, 104-3: Stage, 104a: Through hole, 106: Connecting part, 108: Gap, 110: Suction stage, 120: Airflow regulating stage, 120a: Through hole, 130: Mother sheet, 130a: Surface, 130b: Back side, 132: Sheet-shaped porous titanium body, 132a: First main surface, 132b: Second main surface, 134: Paste, 136: Blank, 136a: Surface, 138: Brown body, 140: Laser, 142: Scanning path, 144: Burr, 146: Protrusion, 148: Recess, 150: Substrate, 152: Shaping device.

Claims

1. A sheet-like porous titanium body, characterized in that, The sheet-like porous titanium body is a sheet-like porous titanium body with a thickness of 40 μm or more and 500 μm or less, and a porosity of 30% or more and 50% or less. The surface roughness of the first principal surface is lower than that of the second principal surface opposite to the first principal surface. The number of first protrusions with a height of 30 μm or more protruding from the periphery on the first main surface side is less than the number of second protrusions with a height of 30 μm or more protruding from the periphery on the second main surface side.

2. The sheet-like porous titanium body according to claim 1, wherein, The maximum height of the first protrusion and the second protrusion is less than 100 μm.

3. The sheet-like porous titanium body according to claim 1 or 2, wherein, The number of the second protrusion is 3.0 or less per 100 mm of the peripheral portion.

4. The sheet-like porous titanium body according to any one of claims 1 to 3, wherein, The first protrusion does not exist.

5. The sheet-like porous titanium body according to any one of claims 1 to 4, wherein, The angles of the sheet-like porous titanium body are arc-shaped.

6. The sheet-like porous titanium body according to any one of claims 1 to 5, wherein, The peripheral portion does not have a bend exceeding 0.1m in height on either the first or second main surface side.

7. The sheet-like porous titanium body according to any one of claims 1 to 6, wherein, The sheet-like titanium porous body is manufactured by cutting a mother sheet with an area larger than that of the sheet-like titanium porous body using a fiber laser.

8. The application of a sheet-like porous titanium body according to any one of claims 1 to 7, wherein, The sheet-like porous titanium body serves as a porous transport layer in a polymer electrolyte membrane-type water electrolysis device.

9. The application according to claim 8, wherein, The polymer electrolyte membrane-type water electrolysis device includes an ion exchange membrane. The ion exchange membrane is configured to contact the first main surface of the sheet-like porous titanium body.

10. A method for preparing hydrogen, characterized in that, Hydrogen is prepared in a polymer electrolyte membrane-type water electrolysis device using the sheet-like porous titanium body according to any one of claims 1 to 7.

11. A method for manufacturing a sheet-like porous titanium body, characterized in that, include: A mother sheet containing a porous titanium body is arranged on a fixture to cover at least one through hole and at least one gap between a stage and a frame. The fixture includes at least one stage having at least one through hole, a frame surrounding and separate from at least one stage, and at least one connecting part connecting the at least one stage to the frame. The mother sheet is adsorbed onto the clamp; as well as The mother sheet is cut by scanning the gap with laser light emitted from a fiber laser.

12. The manufacturing method according to claim 11, wherein, The upper surface of the at least one connecting portion is located on the lower surface side of the at least one platform and the frame, relative to the upper surface of the at least one platform and the frame.

13. The manufacturing method according to claim 11 or 12, wherein, The at least one stage and the frame are made of pure titanium.

14. The manufacturing method according to any one of claims 11 to 13, wherein, The wavelength of the laser is above 1000nm and below 1200nm.

15. The manufacturing method according to any one of claims 11 to 14, wherein, The laser scanning was performed in an argon atmosphere.

16. The manufacturing method according to any one of claims 11 to 15, wherein, The porosity of the mother sheet is above 30% and below 50%.

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