Method for producing sheet-like titanium porous laminate

Abstract

To provide a method for efficiently manufacturing a sheet-like titanium porous laminate having high surface smoothness, air permeability and liquid permeability.SOLUTION: The method for producing a sheet-like titanium porous laminate includes sintering a laminate of a sheet-like first brown body and a co-sintered body disposed between a setter and a shaping substrate. The first brown body contains a first titanium powder having an average particle diameter of 10 μm or more and 45 μm or less. The co-sintered body may be a sheet-shaped second brown body containing a second titanium powder having an average particle diameter larger than the average particle diameter of the first titanium powder.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] One embodiment of the present invention relates to a method for producing a sheet-shaped porous titanium laminate. [Background technology]

[0002] Metallic titanium (zero-valent titanium) has properties such as high specific strength, light weight, and excellent corrosion resistance, and therefore, sheet-shaped porous titanium bodies produced from metallic titanium powder are used as porous transport layers in water electrolysis devices (particularly polymer electrolyte membrane (PEM)-type water electrolysis devices) that are exposed to harsh environments. The sheet-shaped porous titanium body is sometimes placed in contact with the electrolyte membrane within the water electrolysis device. Therefore, to take into consideration the state of contact with the electrolyte membrane and ensure high permeability to water and oxygen, a laminate of multiple sheet-shaped porous titanium bodies with different properties has been proposed (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-151916 [Patent Document 2] Patent No. 7467743 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of one embodiment of the present invention is to provide a novel method for producing a sheet-shaped porous titanium laminate, or an object of one embodiment of the present invention is to provide a method for efficiently producing a sheet-shaped porous titanium laminate that combines high surface smoothness with air and liquid permeability. [Means for solving the problem]

[0005] One embodiment of the present invention is a method for producing a sheet-shaped porous titanium laminate. This method includes sintering a sheet-shaped laminate of a first brown body and a co-sintered body placed between a setter and a shaping substrate. The first brown body contains a first titanium powder having an average particle size of 10 μm or more and 45 μm or less. [Brief explanation of the drawings]

[0006] [Figure 1] 1A and 1B are a schematic perspective view and a side view, respectively, of a sheet-shaped porous titanium laminate obtained by applying one embodiment of the present invention. [Figure 2] 1 is a flowchart showing a method for producing a sheet-shaped porous titanium laminate according to one embodiment of the present invention. [Figure 3] 1 is a schematic side view showing a method for producing a sheet-shaped porous titanium laminate according to one embodiment of the present invention. FIG. [Figure 4] 1 is a schematic top view showing a method for producing a sheet-shaped porous titanium laminate according to one embodiment of the present invention. FIG. [Figure 5] 1A and 1B are a schematic top view and an end view, respectively, showing a method for producing a sheet-shaped porous titanium laminate according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, a sheet-shaped porous titanium laminate and a method for manufacturing the same according to an embodiment of the present invention will be described with reference to the drawings. Here, "sheet-shaped" means a plate-like or foil-like structure having a thickness small relative to its dimensions in a plan view.

[0008] 1. Sheet-shaped porous titanium laminate One embodiment of the present invention is a method for producing a sheet-shaped porous titanium laminate. A schematic perspective view and side view of a sheet-shaped porous titanium laminate obtained according to this production method are shown in Figures 1(A) and 1(B), respectively. As can be seen from these figures, the sheet-shaped porous titanium laminate 100 comprises a first layer 102 and a second layer 104 laminated so as to be in contact with each other.

[0009] The size of the sheet-shaped porous titanium laminate 100 can be determined arbitrarily. For example, the area of ​​the sheet-shaped porous titanium laminate 100 can be set to 1×10 4 mm 2 More than 2.5m 2 The size and shape of the first layer 102 and the second layer 104 can be adjusted to form the following rectangle. The shape and size of the first layer 102 and the second layer 104 may be different from each other, but are preferably the same.

[0010] Both the first layer 102 and the second layer 104 contain metallic titanium, and each layer has a high titanium content. For example, the titanium content of each of the first layer 102 and the second layer 104 is 97% by mass or more and 99% by mass or less. The content of other metallic impurities (e.g., chromium, aluminum, copper, zinc, tin, and iron) is also low, at 0.3% by mass or less. The content of non-metallic impurities (e.g., oxygen, nitrogen, carbon, hydrogen, and chlorine) is also low. For example, the oxygen content is in the range of 0.5% by mass or more and 2.0% by mass or 0.5% by mass or more and 1.5% by mass or less. The titanium content can be calculated by subtracting the content of elements other than titanium from the total amount (100%) of elements contained in the sheet-shaped porous titanium laminate 100. The content of elements other than titanium can be measured by any method. For example, the content of metal elements can be determined by inductively coupled plasma (ICP) atomic emission spectroscopy or X-ray fluorescence elemental analysis. The chlorine content can be measured using the silver nitrate measurement method, the carbon content can be measured using the high-frequency combustion-infrared absorption method, the nitrogen content can be measured using the inert gas fusion-thermal conductivity method, the oxygen content can be measured using the inert gas fusion-infrared absorption method, and the hydrogen content can be measured using the inert gas fusion-thermal conductivity method.

[0011] The first layer 102 and the second layer 104 differ in thickness, surface smoothness, etc. In one example, the thickness of the first layer 102 is smaller than the thickness of the second layer 104, for example, 30 μm or more and 100 μm or less. In contrast, the thickness of the second layer 104 is, for example, 100 μm or more and 1000 μm or less. The thicknesses of the first layer 102 and the second layer 104 may be determined by observing the end face or side face of the sheet-shaped porous titanium laminate 100 with a microscope (optical microscope or electron microscope).

[0012] The smoothness of the surface of the first layer 102 (the surface opposite to the second layer 104) is higher than the smoothness of the surface of the second layer 104 (the surface opposite to the first layer 102). Specifically, the maximum height Rz, which is one parameter indicating the surface smoothness of the first layer 102, is 20 μm or less, and may be, for example, 4 μm or more and 20 μm or less, or 4 μm or more and 10 μm or less. In contrast, the maximum height Rz of the surface of the second layer 104 may be 25 μm or more, or 50 μm or more, or 65 μm or more. The maximum surface height Rz may be determined in accordance with ISO (International Organization for Standardization) 4287-1997.

[0013] As such, the first layer 102 has a smoother surface than the second layer 104. For this reason, the sheet-shaped titanium porous laminate 100 can be suitably used as a porous transport layer in a PEM water electrolysis system. Specifically, by arranging the sheet-shaped titanium porous laminate 100 as a porous transport layer in a PEM water electrolysis system so that the smoother first layer 102 is located on the electrolyte membrane side, deformation and damage to the electrolyte membrane that would be pressed with a large force against the sheet-shaped titanium porous laminate 100 can be prevented. On the other hand, the presence of the second layer 104, which has larger pores, for example, can ensure the air permeability and liquid permeability required for a porous transport layer.

[0014] 2. Method for manufacturing sheet-shaped porous titanium laminate An example of a manufacturing method for the sheet-shaped titanium porous laminate 100 will be described using the flowchart shown in FIG. 2. As shown in the flowchart in FIG. 2, in this manufacturing method, first, a green body that will provide the first layer 102 is prepared. Then, a co-sintered body that will be sintered together with the green body or that will be subjected to the sintering step is laminated with the green body, and the resulting laminate is degreased and sintered to manufacture the sheet-shaped titanium porous laminate 100. As an optional step, the green body and the co-sintered body may be fused together before degreasing. These steps will be described in detail below.

[0015] (1) Preparation of green bodies First, a green body that will provide the first layer 102 is fabricated using a method known as the paste method. Specifically, a titanium paste is prepared containing titanium powder with an average particle size of 10 μm to 45 μm, or 10 μm to 30 μm, or 10 μm to 20 μm, a binder, and an organic solvent. The titanium paste may further contain various additives. The additives may include one or more selected from plasticizers, dispersants, leveling agents, and antifoaming agents. However, foaming agents are not included as additives. The titanium paste is applied to a substrate in a sheet form, and the organic solvent is then removed to obtain a green body, a molded body primarily composed of titanium powder and a binder. Hereinafter, the green body that will provide the first layer 102 will be referred to as the first green body.

[0016] The titanium powder is preferably hydrogenated / dehydrogenated titanium powder (also known as HDH powder), which is obtained by hydrogenating and pulverizing titanium sponge, titanium scrap, titanium castings, titanium forgings, etc., followed by dehydrogenation. The titanium powder has a titanium content of, for example, 97% by mass or more, 98% by mass or more, or 99% by mass or more to 100% by mass or less, and an oxygen content of 0.1% by mass or more to 0.7% by mass or less, or 0.6% by mass or less. Using titanium powder with a low oxygen content can provide a first layer 102 with high electrical conductivity. Furthermore, using fine titanium powder as described above can improve the surface smoothness of the first layer 102. In addition to oxygen, the titanium powder may contain trace amounts of other components, such as nonmetallic elements such as carbon and nitrogen, or metallic elements such as chromium, aluminum, copper, zinc, tin, and iron.

[0017] The planar shape of the titanium particles contained in the titanium powder is preferably circular or angular. In the former case, the shape of the titanium particles is spherical or nearly so (e.g., circularity of 0.95 or more in plan view). In the latter case, the use of titanium powder (typically HDH powder) containing titanium particles with a low circularity (e.g., 0.7 or more but less than 0.95) and a shape that deviates from a sphere increases the number of junctions between the metal particles. As a result, the first layer 102 can be obtained with numerous pores and a sponge-like three-dimensional network structure. The circularity can be calculated as the ratio of the perimeter of the projected surface of the titanium particle to the perimeter of a circle with an area equal to the area of ​​the projected surface.

[0018] In addition to polyvinyl butyral, various polymeric materials can be used as the binder. Examples include polymers with a basic skeleton such as alkylated celluloses (e.g., methyl cellulose and ethyl cellulose), acrylic polymers (e.g., poly(meth)acrylate), and polyvinyl alcohol. In preparing the titanium paste, one type of binder may be used, or two or more types of binders may be used.

[0019] Examples of organic solvents include monohydric alcohols having about 1 to 5 carbon atoms. For example, ethanol, n-propanol, isopropyl alcohol, n-butanol, isobutyl alcohol, and sec-butanol can be used. In addition to these alcohols, other organic solvents that may be used include monoterpene alcohols such as terpineol, ethylene glycol monoalkyl ethers such as butyl carbitol, aromatic hydrocarbons such as toluene, xylene, trimethylbenzene, and tetralin, linear, branched, or cyclic aliphatic hydrocarbons such as hexane, heptane, octane, and cyclohexane, ketones such as methyl ethyl ketone and cyclohexanone, and amide solvents such as N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0020] A wide variety of plasticizers can be used to impart flexibility to the first green body. Examples include esters of bifunctional carboxylic acids such as adipic acid, 1,2-cyclohexanedicarboxylic acid, and fumaric acid with branched or linear long-chain alcohols having 8 to 12 carbon atoms, such as nonanol, isononanol, and octanol. Alternatively, polyesters obtained by polycondensation of bifunctional carboxylic acids with bifunctional alcohols can be used. In this case, the alkylene group between the two hydroxyl groups of the bifunctional alcohol preferably has 6 to 12 carbon atoms. Other examples of plasticizers that can be used include oligomers of (meth)acrylic acid or (meth)acrylic acid esters, polyethylene glycol, oligoethylene glycol, or their ether or ester derivatives. Alternatively, monoesters, diesters, and triesters of glycerin with unsaturated fatty acids such as ricinoleic acid, oleic acid, and linoleic acid, or saturated fatty acids such as palmitic acid and stearic acid, can be used.

[0021] The dispersant is an additive that has the function of suppressing aggregation of the titanium powder and promoting dispersion, and examples of the dispersant include ionic surfactants such as alkylbenzene sulfonates and polycarboxylic acid amines, and nonionic surfactants exemplified by polyethylene glycol fatty acid esters such as polyoxyethylene monolaurate. Coal tar naphtha may also be used as a dispersant.

[0022] The leveling agent may be an acrylic polymer-based leveling agent, a silicone-based leveling agent, or a fluorine-based leveling agent. The leveling agent may contain a solvent. Examples of the solvent include aliphatic hydrocarbons, aromatic hydrocarbons, alcohols, and ethers. The use of a leveling agent significantly reduces the surface tension of the titanium paste, improving the flatness of the titanium paste applied to the substrate and the first green body obtained by drying it. As a result, a first layer 102 with a uniform thickness can be obtained.

[0023] A wide range of defoaming agents can be used that can suppress the generation of bubbles in the titanium paste or that can quickly break or defoam any bubbles that do occur, and examples include those that contain a polymer such as an olefin polymer (polyolefin), an acrylic polymer, polyvinyl ether, or a diene polymer and a solvent.

[0024] A titanium paste can be obtained by mixing titanium powder, an organic solvent, a binder, and additives that are added as needed. The composition of the titanium paste can be set as appropriate; for example, the mass ratio of titanium powder to binder to organic solvent (titanium powder:binder to organic solvent) can be set in the range of 1:1 to 10:1, or 1:1 to 5:1. The mass ratio of binder to organic solvent (binder:organic solvent) can be set in the range of 1:10 to 1:2. There are no restrictions on the order in which these components are mixed. There are also no restrictions on the mixing method; the titanium paste can be prepared using a known stirrer or mixer as appropriate.

[0025] Next, as shown in FIG. 3(A), the obtained titanium paste 112 is applied to a substrate 110. Examples of materials contained in the substrate 110 include polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyolefins such as polyethylene, polypropylene, and polystyrene, polyvinyl acetate-based polymers such as polyvinyl acetate and partially saponified polyvinyl acetate, and polylactic acid. Among these, polyethylene terephthalate is preferred because it can be molded into a film with high flexibility and sufficient strength and is inexpensively available. The thickness of the applied titanium paste 112 can be adjusted appropriately taking into account the thickness of the first layer 102 after sintering.

[0026] The titanium paste 112 can be applied by any suitable method, including doctor blade coating, lip coating, offset printing, and gravure printing. For example, the titanium paste 112 can be applied using a variety of deposition devices, including a rear doctor coater, blade coater, rod coater, knife coater, squeeze coater, impregnation coater, reverse roll coater, transfer roll coater, gravure coater, kiss roll coater, slot die coater, cast coater, spray coater, curtain coater, calendar coater, extrusion coater, and bar coater. The doctor blade method, which allows the titanium paste 112 to be continuously applied to a long substrate 110, is preferred. A long substrate 110 allows the sheet-like first green body to be wound into a roll, allowing for efficient storage and transportation. A release agent may be applied to the substrate 110 before the titanium paste 112 is applied. Alternatively, the substrate 110 may be pre-applied with a release agent. The release agent may be, for example, a solution or dispersion of a fluororesin or silicone resin. By applying the release agent, the first green body obtained by drying the titanium paste 112 can be easily separated from the substrate 110.

[0027] Subsequently, the applied titanium paste 112 is dried. In other words, the organic solvent contained in the titanium paste 112 is volatilized. The drying temperature may be determined appropriately in consideration of the composition of the titanium paste, and is, for example, dried at a temperature of about 80°C or higher and 170°C or lower. This allows the first green body to be formed on the substrate 110. Drying may be performed under either normal pressure or reduced pressure. It is preferable to dry the titanium paste 112 while exhausting the air surrounding the titanium paste 112. The atmosphere during drying may also be set as desired, and drying may be performed in an atmosphere of air, nitrogen, oxygen, helium, argon, or a mixture of these gases.

[0028] The above steps result in the production of a first green body. As described above, titanium powder with a small average particle size is used in the production of the first green body. Therefore, the subsequent sintering step can produce a first layer 102 with a relatively low porosity but an extremely smooth surface (the surface opposite the second layer 104, which was in contact with the substrate 110). Furthermore, because no foaming agent is added to the titanium paste 112, the generation of bubbles is suppressed during the preparation and drying of the titanium paste 112. If bubbles are contained in the titanium paste 112, they may remain after application to the substrate 110. If subsequent steps are performed while the bubbles remain, the surface smoothness of the resulting first layer 102 may be lost. Therefore, it can be said that not adding a foaming agent also contributes to the formation of a first layer 102 with a high degree of surface smoothness.

[0029] (2) Lamination of green body and co-sintered body Various sheet-like compacts containing titanium can be used as the co-sintered body. One such compact is similar to the first green body described above. Specifically, a green body can be produced using titanium powder with a larger average particle size than the titanium powder used to produce the first green body, and this can be used as the co-sintered body. Hereinafter, the green body used as the co-sintered body will be referred to as the second green body.

[0030] More specifically, the second green body is fabricated in the same manner as the first green body using titanium powder having a larger average particle size than the titanium powder used to fabricate the first green body, and having an average particle size of 10 μm to 150 μm, 25 μm to 150 μm, 40 μm to 150 μm, or 25 μm to 80 μm. The shape of the titanium powder may be the same as that of the titanium powder used to fabricate the first green body. Alternatively, titanium powder containing titanium fine particles with a higher aspect ratio (e.g., fibrous titanium fine particles) may be used. The second green body fabricated using titanium powder containing titanium fine particles with a high aspect ratio can have a nonwoven three-dimensional network structure. Therefore, the second green body can have a larger porosity than the first green body. The second green body may be fabricated so that its thickness is greater than that of the first green body. The aspect ratio may be determined as the ratio of the length in the direction perpendicular to the longitudinal direction of the projection surface of the titanium fine particle.

[0031] Unlike the production of the first green body, a foaming process may be performed when producing the second green body. The foaming process can be performed, for example, by adding a foaming agent when preparing a titanium paste and then heating the titanium paste. This causes the foaming agent to generate gas, creating bubbles. Examples of foaming agents include N,N'-dinitropentamethylenetetramine and 4,4'-oxybisbenzenesulfonylhydrazide, which generate gas when heated. The heating temperature can also be set appropriately depending on the foaming agent, and can be selected from a range of 30°C to 60°C, for example. Performing the foaming process allows a large number of bubbles to be formed in the second green body, resulting in the formation of more pores in the second layer 104.

[0032] To stack the first green body and the co-sintered body, first, as shown in FIG. 3(B), the first green body 114, which has been peeled from the substrate 110, is placed on a setter 120, which functions as a support substrate. The co-sintered body 116 is then placed on the first green body 114 (FIG. 3(C)). If the co-sintered body 116 is a second green body, the second green body peeled from the substrate 110 is placed on the first green body 114. The second green body is produced independently of the first green body. Unlike titanium paste, green bodies have extremely low fluidity. Therefore, even if the co-sintered body 116, which is the second green body, contains a large amount of bubbles, the transfer of the foaming agent and bubbles to the first green body 114 due to contact between the first and second green bodies is prevented.

[0033] 3(D), a shaping substrate 122 is placed on the co-sintered body 116. Therefore, the first green body 114 and the co-sintered body 116 are positioned on the setter 120 side and the shaping substrate 122 side, respectively, and the stack 118 of the first green body 114 and the co-sintered body 116 is sandwiched between the setter 120 and the shaping substrate 122 so that the first green body 114 and the co-sintered body 116 are in contact with the setter 120 and the shaping substrate 122, respectively. At this time, as shown in FIG. 4, the stack 118 is placed between the setter 120 and the shaping substrate 122 so that the entire stack 118 overlaps the setter 120 and the shaping substrate 122. Therefore, the areas of the setter 120 and the shaping substrate 122 (areas of the main surfaces; the same applies hereinafter) are all equal to or greater than the areas of the first green body 114, the co-sintered body 116, and the stack 118. Preferably, the area of ​​the first green body 114, the area of ​​the co-sintered body 116, or the area of ​​the laminate 118 (A G ) relative to the area of ​​the setter 120 or the area of ​​the shaping substrate 122 (A S ) ratio (A S / A G ) is 1.0 or more and 5.0 or less, or 1.0 or more and 3.0 or less. When the shaping substrate 122 is placed on the laminate 118, the area (A S ) for the ratio (A S / A G) may be 1.0 or more and 1.5 or less. By satisfying this size relationship, not only the center portion but also the peripheral portion of the laminate 118 can be sandwiched between the setter 120 and the shaping substrate 122 in the subsequent process.

[0034] The setter 120 and the shaping substrate 122 are configured to contain graphite, a heat-resistant porous sintered carbon material, as well as ceramics such as boron nitride and yttrium oxide, or high-melting-point metals such as molybdenum and tantalum. This configuration prevents elements contained in the setter 120 or the shaping substrate 122 from diffusing into the first green body 114 or the co-sintered body 116 during sintering, or from forming a eutectic with titanium contained in the first green body 114 or the co-sintered body 116. The setter 120 and the shaping substrate 122 may contain materials other than those mentioned above, but the surfaces in contact with the laminate 118 are configured to contain the above materials. This prevents the laminate 118 from adhering to the setter 120 or the shaping substrate 122. Preferably, the shaping substrate 122 in contact with the co-sintered body 116 is a porous material with a smaller thickness than the setter 120. The thickness of the shaping substrate 122 is preferably 0.5 mm to 2 mm. Setting the thickness within this range allows efficient transfer of heat from the shaping substrate 122 to the laminate 118, accelerating debinding and sintering, and also allows gas generated during the debinding process to be rapidly desorbed. When the second green body is used as the co-sintered body 116, the co-sintered body 116 has a higher volume fraction in the laminate 118, and therefore the amount of gas generated from the co-sintered body 116 during the debinding process is greater than that of the first green body 114. Therefore, by using a thin porous body as the shaping substrate 122, gas generated during the debinding process can be effectively desorbed.

[0035] For this reason, the shaping substrate 122 may have a plurality of through holes 122a, as shown in, for example, FIG. 5(A) and a schematic diagram of an end surface thereof taken along the chain line AA' (FIG. 5(B)), and may be a mesh, expanded metal, or punched metal containing or made of a high-melting-point metal. The openings of the through holes 122a on the upper and lower surfaces of the shaping substrate 122 may overlap each other in the normal direction of the shaping substrate 122. Alternatively, the shaping substrate 122 may be a lotus metal or the like.

[0036] In the above example, the first green body 114, the co-sintered body 116, and the shaping substrate 122 are sequentially arranged on the setter 120. However, there are no restrictions on the stacking order of these components, and the co-sintered body 116, the first green body 114, and the setter 120 may be sequentially arranged on the shaping substrate 122.

[0037] (3) Welding When the co-sintered body 116 is a second green body, the first green body 114 and the co-sintered body 116 may be fused together as an optional step. The fusion is performed by heating the laminate 118 while applying pressure at a temperature lower than that of the subsequent debinding step. For example, pressure is applied in the thickness direction to the laminate 118 sandwiched between the setter 120 and the shaping substrate 122. The pressure at this time is, for example, 0.15 N / cm. 2 In this state, the laminate 118 is heated at a temperature of 100°C to 200°C. This removes traces of residual organic solvent and bonds the first green body and the co-sintered body 116 via the binder. There is no upper limit to the pressure, and it may be set appropriately within a range that allows the sheet-shaped porous titanium laminate 100 obtained by sintering to have a large number of pores. For example, the upper limit of the pressure is 100 N / cm 2 That's fine too.

[0038] (4) Degreasing Next, debinding is performed to remove the binder and additives from the first green body 114. If the co-sintered body 116 is a second green body, the second green body is also debinding simultaneously. Specifically, the laminate 118 sandwiched between the setter 120 and the shaping substrate 122 is heated to a temperature at which the binder and additives decompose and / or volatilize. For example, the laminate 118 is heated in an oxygen-containing atmosphere, such as air, at a temperature between 300°C and 450°C for a period of 2 hours to 20 hours. During this process, no additional pressure is applied to the laminate 118; instead, the co-sintered body 116 is pressed against the first green body 114 using the pressure generated by the mass of the shaping substrate 122 or the setter 120 placed on the laminate 118. The debinding process removes all or most of the binder and additives. The sheet-like compact obtained by debinding the green body is called a Brown body. Debinding may be performed without the welding process described above.

[0039] (5) Sintering Sintering is also performed with the laminate 118 sandwiched between the setter 120 and the shaping substrate 122. Since debinding is performed before sintering, the laminate 118 after debinding contains a first Brown body formed from the first green body 114 instead of the first green body 114. Similarly, when the co-sintered body 116 is a second green body, the laminate 118 after debinding contains a second Brown body formed by debinding the second green body instead of the second green body. The heating temperature for sintering is appropriately selected from temperatures of approximately 775°C or higher and 850°C or lower. Sintering is performed at atmospheric pressure or reduced pressure. When sintering at atmospheric pressure, it is preferable to perform sintering in an atmosphere with low concentrations of oxygen and nitrogen, for example, a rare gas atmosphere such as helium or argon, to prevent the formation of oxides and nitrides. When sintering under reduced pressure, the pressure is, for example, 1×10 -4 Pa or more 1×10 -2The pressure may be set appropriately within a range of 100 Pa or less. The sintering time may also be set appropriately depending on the thickness of the first green body 114 and the co-sintered body 116, and may be selected, for example, from a range of 1 hour to 8 hours. As in the debinding step, during sintering, no additional pressure may be applied to the laminate 118, and the co-sintered body 116 may be pressed against the first green body 114 using the pressure generated by the mass of the shaping substrate 122 or setter 120 placed on the laminate 118. After sintering is complete, the setter 120 and shaping substrate 122 are removed, and the sheet-shaped porous titanium laminate 100 can be obtained.

[0040] As described above, in the manufacturing method for the sheet-shaped titanium porous laminate 100 according to one embodiment of the present invention, the debinding step and the sintering step are carried out in a state in which the laminate 118 of the first green body 114 and the co-sintered body 116 is sandwiched between the setter 120 and the shaping substrate 122. The laminate 118 is also disposed between the setter 120 and the shaping substrate 122 so that the entire laminate 118 overlaps the setter 120 and the shaping substrate 122. Therefore, the debinding and sintering of the laminate 118 are carried out in a state in which the entire laminate 118, including not only the center but also the peripheral edge, maintains a flat shape. Therefore, as shown in the examples, deformation of the laminate 118 due to differences in thickness between the first green body 114 and the co-sintered body 116, differences in debinding and / or sintering behavior, etc. (e.g., warping at the peripheral portion, separation, peeling, curvature, or wrinkles between the first green body 114 and the co-sintered body 116 due to warping of the co-sintered body 116, etc.) can be prevented without repeating multiple sintering steps. As a result, a step of cutting and removing deformed portions is unnecessary, allowing for efficient production of large-area porous titanium laminates. Furthermore, since there is no need to remove deformed portions when cutting and shaping large-area porous titanium laminates, titanium porous laminates of any shape and size can be efficiently obtained from large-area porous titanium laminates. These features of the present manufacturing method suppress yield declines and contribute to the production of large porous titanium laminates at lower cost.

[0041] 3. Variations In the above example, the first green body 114 is used as the molded body that provides the first layer 102, and the second green body containing titanium powder is used as the co-sintered body 116. However, the method for producing the sheet-shaped titanium porous laminate 100 according to one embodiment of the present invention is not limited to this example, and various molded bodies can be used.

[0042] (1) Variation 1 Alternatively, the laminate 118 may be degreased without the shaping substrate 122 placed thereon, and then the shaping substrate 122 may be placed on the degreased laminate 118, followed by sintering. Specifically, a titanium paste 112 prepared using titanium powder with an average particle size of 10 μm to 45 μm according to the method described above is applied to the substrate 110 and dried to produce a first green body 114 (see FIG. 3(A)). The first green body 114 is then peeled from the substrate 110 and placed on a setter 120, the co-sintered body 116 is stacked thereon, and the laminate 118 is degreased without the shaping substrate 122 placed thereon. The degreasing conditions are as described above. The shaping substrate 122 is then placed on the laminate 118, and sintering is carried out in this state under the conditions described above.

[0043] In this modification (1), the first green body 114 that provides the first layer 102 is also produced using titanium powder with a small average particle size as one of the raw materials. As a result, the surface of the resulting first layer 102 has high smoothness, and the second layer 104 can ensure higher air and liquid permeability than the first layer 102.

[0044] (2) Variation 2 Alternatively, a metal plate made of metallic titanium and having a plurality of through holes (i.e., a metallic titanium sheet having a plurality of through holes) can be used as the co-sintered body 116. Specifically, a plate-shaped titanium mesh, expanded metal, punched metal, lotus metal, or the like can be used as the co-sintered body 116. The thickness of the metal plate may be set to, for example, 100 μm or more and 1000 μm or less. For example, debinding and sintering are performed in a state where the laminate 118 is sandwiched between the setter 120 and the shaping substrate 122, with the first green body 114 and the metal plate positioned on the setter 120 side and the shaping substrate 122 side, respectively.

[0045] Alternatively, the co-sintered body 116 may be a second brown body obtained by debinding a second green body, or a sheet-shaped porous titanium body (second sheet-shaped porous titanium body) obtained by further sintering this second brown body. In this case, the debinding of the second green body and the sintering of the second brown body may be carried out independently of the debinding and sintering of the first green body 114. In this case, the debinding and sintering of the first green body 114 are carried out with the laminate 118 sandwiched between the setter 120 and the shaping substrate 122, so that the first green body 114 and the second brown body (or the second sheet-shaped porous titanium body) are located on the setter 120 side and the shaping substrate 122 side, respectively.

[0046] Alternatively, the co-sintered body 116 may be a sheet-shaped porous titanium body formed using a dry method. In the dry method, titanium powder, preferably titanium powder containing fibrous titanium particles, is deposited on a setter 120, then scraped into a sheet shape, and then heated and sintered at a high temperature (e.g., 950°C or higher) to produce a sheet-shaped porous titanium body.

[0047] In variant (2), the first green body 114 is also produced by the paste method using titanium powder with a small average particle size, so that one surface of the sheet-shaped titanium porous laminate 100 formed by degreasing and sintering the first green body 114, i.e., the surface of the first layer 102, has high smoothness. On the other hand, the second layer 104 can ensure higher air and liquid permeability than the first layer 102.

[0048] It is also possible to combine variants (1) and (2). For example, a laminate of the first green body 114 and a metallic titanium sheet, a laminate of the first green body 114 and a second Brown body, a laminate of the first green body 114, a second Brown body and a metallic titanium sheet, or a laminate of the first green body 114 and a sheet-like porous titanium body is placed on a setter and degreased without using a shaping substrate 122. Sintering may then be carried out with the shaping substrate 122 placed on the laminate. [Example]

[0049] In this example, an example will be described in which a sheet-shaped porous titanium laminate was produced using the above-described manufacturing method.

[0050] 1. Example 1 A titanium paste containing HDH titanium powder (Toho Tech Co., Ltd., Model No. TC-201, 165 g) with an average particle size (by volume) of 14 μm, a binder polyvinyl butyral (Sekisui Chemical Co., Ltd., Model No. S-LEC BL-1, 15 g), an organic solvent isopropyl alcohol (22.5 g), and a dispersant (SN-Sparce 2190 from San Nopco Ltd., 0.3 g, a dispersant containing 42% by weight of coal tar naphtha and 58% by weight of polycarboxylic acid amine salts, etc.) was prepared, coated onto a polyethylene terephthalate substrate in sheet form, and dried at 110°C to prepare a first green body (planar shape: approximately 20 cm x 25 cm). A 10 cm x 10 cm green body was cut from approximately the center of this green body.

[0051] A titanium paste containing HDH titanium powder (Toho Tech Co., Ltd., Model No. TC-450, 165 g) with an average particle size (by volume) of 26 μm, a binder polyvinyl butyral (Sekisui Chemical Co., Ltd., Model No. S-LEC BL-1, 15 g), an organic solvent isopropyl alcohol (22.5 g), and a dispersant (San Nopco Ltd., SN Sparce 2190, a dispersant containing 42% by weight of coal tar naphtha and 58% by weight of polycarboxylic acid amine salts, 0.3 g) was prepared. The paste was coated onto a polyethylene terephthalate substrate in sheet form and dried at 110°C to prepare a second green body (planar shape: approximately 20 cm x 25 cm). A 10 cm x 10 cm green body was cut from approximately the center of this green body.

[0052] The first and second green bodies were placed in this order on a graphite setter (12 cm x 22 cm), and a graphite shaping substrate (10 cm x 10 cm) was placed on top of the second green body. A pressure of 0.73 N / cm was applied to the first and second green bodies in the thickness direction. 2 The mixture was degreased at 380°C for 12 hours with a pressure of 100µm applied, and then sintered for 1 hour at 840°C. The thicknesses of the first and second layers of the obtained porous titanium sheet laminate were 100µm and 250µm, respectively.

[0053] 2. Example 2 A sheet-shaped titanium porous laminate was obtained in the same manner as in Example 1, except that a molybdenum mesh (100 mesh, 10 cm×10 cm) was used in place of the graphite shaped substrate.

[0054] 3. Example 3 A sheet-shaped titanium porous laminate was obtained in the same manner as in Example 1, except that the second green body was produced using HDH titanium powder (manufactured by Toho Tech Co., Ltd., model number TC-750, 165 g) having an average particle size (volume basis) of 42 μm instead of HDH titanium powder (manufactured by Toho Tech Co., Ltd., model number TC-450, 165) having an average particle size (volume basis) of 26 μm.

[0055] 4. Comparative Example A sheet-shaped porous titanium laminate was obtained in the same manner as in Example 1, without using a shaped substrate.

[0056] 5. Evaluation (1) Deformation of the porous titanium sheet laminate Three experiments were carried out for each of Examples 1 to 3. However, in none of the experiments was any curved portion observed in the sheet-shaped porous titanium laminate obtained, and a flat sheet-shaped porous titanium laminate was obtained throughout.

[0057] In contrast, in one of the three experiments in the comparative example, a warp up to 2 mm in height was observed around the periphery of the sheet-shaped porous titanium laminate when laid flat. Furthermore, the area of ​​the flat sheet-shaped porous titanium laminate obtained by cutting away the warp around the periphery was 80% of that obtained in Example 1. In other words, it was found that a loss of 20% occurs in order to obtain a sheet-shaped porous titanium laminate that is flat all over.

[0058] (2) Surface smoothness The surface roughness of both sides of the sheet-shaped porous titanium laminate obtained in each Example was measured. Specifically, a small surface roughness measuring instrument, Surftest SJ-210, manufactured by Mitutoyo Corporation, was used to measure the maximum surface height Rz at three measurement points for each of the sheet-shaped porous titanium laminates obtained in Examples 1 to 3, and the average value of these was calculated. The results are shown in Table 1.

[0059] [Table 1]

[0060] As shown in Table 1, it was confirmed that the surface roughness of the surface on the first layer side was extremely low in all of Examples 1 to 3. Compared to Example 1, the surface roughness of the surface on the first layer side in Example 3 was slightly higher, but it can be said that a sufficiently high level of smoothness was obtained. From the above results, it was found that by applying an embodiment of the present invention, it is possible to produce a sheet-shaped porous titanium laminate that has extremely high smoothness and is composed of a thin first layer and a second layer with a high porosity and volume fraction.

[0061] (3) Carbon content The carbon contents of the sheet-shaped porous titanium laminates obtained in Examples 1 to 3 and the Comparative Example were measured using a high-frequency combustion-infrared absorption method. The results confirmed that all sheet-shaped porous titanium laminates had low carbon contents of 0.10 mass% or less. This means that even if a laminate of a first green body and a second green body is degreased and sintered with a graphite shaping substrate in contact, the binder derived from the paste is expelled from the laminate, and carbon does not substantially diffuse from the shaping substrate. Therefore, it can be said that by utilizing embodiments of the present invention, it is possible to produce sheet-shaped porous titanium laminates that are unlikely to increase in carbon content and have extremely high smoothness.

[0062] Based on the above-described embodiments of the present invention, those skilled in the art may add, delete, or modify components, or add, omit, or modify processes as appropriate, as long as they comply with the spirit of the present invention. Even if there are other effects and advantages different from those achieved by the aspects of the above-described embodiments, those that are clear from the description in this specification or that can be easily predicted by those skilled in the art are naturally considered to be achieved by the present invention. [Explanation of symbols]

[0063] 100: sheet-shaped titanium porous laminate, 102: first layer, 104: second layer, 110: substrate, 112: titanium paste, 114: first green body, 116: co-sintered body, 118: laminate, 120: setter, 122: shaped substrate, 122a: through-hole, 124: third Brownian body

Claims

1. sintering a laminate of the sheet-like first brown body and the co-sintered body disposed between a setter and a shaping substrate; A method for producing a sheet-shaped porous titanium laminate, wherein the first Brown body contains a first titanium powder having an average particle size of 10 μm or more and 45 μm or less.

2. 2. The method according to claim 1, wherein the co-sintered body is a sheet-shaped second brown body containing a second titanium powder having an average particle size larger than the average particle size of the first titanium powder.

3. The manufacturing method according to claim 2 , wherein the second titanium powder has a fibrous shape.

4. The manufacturing method according to claim 1, wherein the laminate is produced by degreasing a sheet-shaped first green body containing the first titanium powder and the co-sintered body while the first green body is stacked between the setter and the shaping substrate.

5. 3. The manufacturing method according to claim 2, wherein the laminate is produced by degreasing a sheet-shaped first green body containing the first titanium powder and a sheet-shaped second green body containing the second titanium powder while they are stacked between the setter and the shaping substrate, thereby converting the first green body and the second green body into the first brown body and the second brown body, respectively.

6. The manufacturing method according to claim 1 , wherein the laminate is placed between the setter and the shaping substrate so that the entire laminate overlaps the setter and the shaping substrate.

7. the first green body and the second green body are welded together before the debinding of the first green body and the second green body; The welding is performed at a temperature of 100° C. or higher and 200° C. or lower, with a force of 0.15 N / cm between the first green body and the second green body. ２ The method according to claim 5, wherein the method is carried out by applying a pressure equal to or greater than the above.

8. The manufacturing method according to claim 1 , wherein the co-sintered body is a titanium metal sheet having a plurality of through holes.

9. The manufacturing method according to claim 1 , wherein the shaped substrate is a porous body or a metal mesh having a plurality of through holes.

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