Method for manufacturing porous metal bodies

Abstract

Provided is a method which is for manufacturing a porous metal body and by which a porous metal body, which has a suppressed variation in thickness even when a molding plate having a relatively small thickness is used multiple times, can be manufactured. This method for manufacturing a porous metal body involves performing a process multiple times, the process including: a depositing step for depositing metal powders in a dry manner on a molding plate 100, which is made of carbon and has a thickness of at most 30 mm and an area of a surface, on which metal powders are deposited, of at least 36 cm2; and a sintering step for sintering the metal powders on the molding plate 100, wherein the plurality of the processes are performed using the same molding plate 100, and at least one process among the plurality of the processes further includes, between the depositing step and the sintering step, a thickness adjusting step for adjusting the thickness of the metal powder-deposited layer on the molding plate 100 while making a surface 105 of the molding plate 100 have a flat surface shape.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a porous metal body.

Background Art

[0002] Titanium is known to be a material with excellent corrosion resistance due to the formation of a passive film on its surface. Utilizing such high corrosion resistance, for example, it is expected to use titanium or titanium alloys for porous conductive materials that are used in environments where they can be corroded and require the required air permeability or liquid permeability. Also, considering cost, it is also conceivable to adopt a porous material such as stainless steel.

[0003] As something that can be used for a porous conductive material having good air permeability and liquid permeability, for example, in Patent Document 1, "a porous titanium-based sintered body having a porosity of 50 to 75%, an average pore diameter of 23 to 45 μm, a specific surface area of 0.020 to 0.065 m 2 / g, and a bending strength of 22 MPa or more" is disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] According to the above Patent Document 1, when manufacturing a sheet-like porous metal body, titanium-based powder is filled into a quartz mold under dry and unpressurized conditions, and after scraping off the titanium-based powder that overflows above the upper end of the mold, the titanium-based powder is sintered in a heating furnace in a state where it is filled in the mold.

[0006] Incidentally, when sintering a large amount of metal powder in a single sintering process in a heating furnace with a predetermined internal volume, it is conceivable to thin the mold on which the metal powder is deposited. Furthermore, from the viewpoint of thinning, it is also conceivable to replace the mold with a relatively thin, flat molding plate. However, when the operation of depositing metal powder on such a molding plate and sintering the metal powder on the molding plate in a heating furnace was repeated multiple times with the same molding plate, it was confirmed that the edges of the molding plate that had been used repeatedly would lift and warp. The reason for this warping is not clear, but it is thought to be due to the metal powder on the molding plate shrinking as it is bonded to the molding plate during sintering, deforming the molding plate. When a molding plate that has warped was used for sintering metal powder, it was confirmed that there was a tendency for variations in thickness to occur within the porous metal body, which is the sintered body.

[0007] Therefore, in one embodiment of the present invention, the objective is to provide a method for manufacturing a porous metal body in which variations in thickness are suppressed even when relatively thin molded plates are used multiple times. [Means for solving the problem]

[0008] As a result of diligent research, the inventors have discovered that even if a molded plate has been used multiple times, by adjusting the thickness of the deposited layer formed by depositing metal powder on the molded plate while making the surface of the molded plate flat, a good porous metal body can be produced without making the surface of the molded plate flat during sintering. They also found that this approach is possible by using a molded plate made of carbon.

[0009] In other words, the present invention, in one aspect, is made of carbon, has a thickness of 30 mm or less, and has a surface area of ​​36 cm² on which metal powder is deposited. 2The method for manufacturing a porous metal body involves performing a process multiple times, which includes a deposition step of dryly depositing metal powder onto a molded plate as described above, and a sintering step of sintering the metal powder on the molded plate after the deposition step, using the same molded plate for each of the multiple processes, and further including a thickness adjustment step between the deposition step and the sintering step, in which the thickness of the deposited layer of metal powder on the molded plate is adjusted while making the surface of the molded plate flat.

[0010] In one embodiment of the method for producing a porous metal body according to the present invention, in the sintering step, the metal powder is sintered at a temperature of 800°C or higher.

[0011] In one embodiment of the method for manufacturing a porous metal body according to the present invention, in the thickness adjustment step, the thickness of the metal powder deposit layer on the molded plate is adjusted while pressing at least a portion of the edge of the surface of the molded plate downward.

[0012] In one embodiment of the method for producing a porous metal body according to the present invention, the metal powder includes one or more selected from pure titanium powder, titanium alloy powder, steel powder, and iron alloy powder.

[0013] In one embodiment of the method for manufacturing a porous metal body according to the present invention, in the sintering step, 30 or more of the molded plates are placed in a heating furnace, and the metal powder on each molded plate is sintered in the heating furnace.

[0014] In one embodiment of the method for manufacturing a porous metal body according to the present invention, the average thickness of the porous metal body is 0.1 to 1.0 mm. [Effects of the Invention]

[0015] According to one embodiment of the present invention, a porous metal body can be manufactured in which variations in thickness are suppressed even when relatively thin molded plates are used multiple times. [Brief explanation of the drawing]

[0016] [Figure 1] It is a schematic plan view for explaining the region where the HDH titanium powder is deposited in Examples 1 to 2 and Comparative Examples 1 to 4. [Figure 2] (A) to (F) are diagrams for explaining a method for manufacturing a porous metal body in an example. [Figure 3] It is a schematic plan view for explaining the location where the surface of the forming plate in Examples 1 to 2 and Comparative Example 4 is clamped by a vise. [Embodiments for Carrying Out the Invention]

[0017] The present invention is not limited to the embodiments described below, and components can be modified and embodied without departing from the gist thereof. Also, various inventions can be formed by appropriately combining a plurality of components disclosed in each embodiment. For example, an invention may be formed by deleting some components from all the components shown in the embodiment. Note that in the drawings, there are some members shown schematically to assist in understanding the embodiments included in the invention, and the sizes, positional relationships, etc., shown in the drawings may not always be accurate.

[0018] [Method for Manufacturing a Porous Metal Body] One embodiment of the method for manufacturing a porous metal body according to the present invention repeatedly performs a process including a deposition step and a sintering step. In one embodiment, at least one of the multiple processes further includes a thickness adjustment step between the deposition step and the sintering step. In the multiple processes, a porous metal body having substantially the same characteristics can be manufactured using the same forming plate. Note that the process may include any steps other than the above steps. Hereinafter, preferred embodiments of each step will be described.

[0019] [Deposition Step] In the deposition step, the metal powder is deposited dry on a forming plate made of carbon. In the deposition step, the metal powder may be deposited on the forming plate without making the surface of the forming plate flat, or the metal powder may be deposited on the forming plate while making the surface of the forming plate flat. That is, in order to manufacture a porous metal body with little variation in its thickness, in the thickness adjustment step described later, it is important to adjust the thickness of the deposition layer formed by the deposition of the metal powder on the forming plate while making the surface of the forming plate flat. For example, when it is determined that the surface of the forming plate used in the deposition step is not flat, in the deposition step, any part of the surface may be pressed downward so that the surface of the forming plate becomes flat, and the metal powder may be deposited on the forming plate in that state. In this case, it is preferable from the viewpoint of work simplification that the downward pressing continues until the thickness adjustment of the deposition layer is completed. Specifically, as the pressing means, there is a vise or the like, and a part of the forming plate may be sandwiched with a vise or the like and pressed downward so that the surface of the forming plate becomes flat. As the position to be sandwiched with a vise or the like, it can be a part such as the edge part of the surface of the forming plate. For example, it is preferable to sandwich at least a part of a pair of opposing edge parts on the long side or the short side of a rectangular forming plate in plan view with a pedestal member having a horizontal plane and the forming plate on the horizontal plane together. Further, in the case of a forming plate that is circular or elliptical in plan view, it is preferable to sandwich at least a part of its edge part with a pedestal member having a horizontal plane and the forming plate on the horizontal plane together. When there are, for example, two positions where the forming plate and the pedestal member are sandwiched with a vise or the like, it is sufficient that the positions where they are sandwiched face each other via a symmetry axis passing through the center or the center of gravity of the surface of the forming plate in plan view. For example, two corner parts 104 of the forming plate 100 may be sandwiched with a vise and pressed downward (see FIG. 3). Also, in the deposition step, as described above, the metal powder may be deposited on the forming plate without making the surface of the forming plate flat. In such a case, in the thickness adjustment step described later, the thickness of the deposition layer formed by the deposition of the metal powder on the forming plate can be adjusted while making the surface of the forming plate flat using a vise or the like.

[0020] Furthermore, in the deposition step, the metal powder is deposited on the molded plate using a dry method. Dry deposition has the advantage of making it easy to adjust the deposition thickness afterward, and consequently, to control the thickness of the porous metal body. Here, "dry method" means that no liquids such as solvents or binders are used. In the deposition step, instead of settling the metal powder in a slurry in which the metal powder is dispersed in a liquid, the metal powder is deposited by dropping it, for example, in a gas such as air or in a vacuum. In this case, the metal powder is not intentionally pressurized in the direction of deposition.

[0021] (molded plate) The molded plate is made of carbon, as it possesses the required flexibility (elastic deformability) and heat resistance. In one embodiment, by using such a molded plate, even if the surface of the molded plate is pressed downwards to become flat during the deposition step or thickness adjustment step, the occurrence of cracks or fissures in the molded plate is suppressed. Therefore, the effort required to prepare new molded plates is reduced, and production efficiency is improved. Furthermore, when molded plates made of metal oxides such as BN (boron nitride) or SiO2 (quartz) are subjected to multiple sintering processes, the molded plates deform due to repeated heating and cooling. However, when attempting to straighten a deformed molded plate made of metal oxides such as quartz into a flat shape, cracks or fissures often occur in the molded plate. For these reasons, from the viewpoint of increasing the number of times the molded plate can be used, a molded plate made of carbon is preferred. From the perspective of manufacturing a sheet-like porous metal body, the molded plate is flat. Furthermore, from the perspective of increasing the productivity of thin sheet-like porous metal bodies, a mold with a space partitioned inside the peripheral wall for packing metal powder (sometimes called a counterbore mold) is unsuitable. With a counterbore mold, not only the bottom plate but also the peripheral wall can deform, making the straightening process complicated and disadvantageous from the standpoint of production efficiency, or the straightening itself may not be successful. The shape of the molded plate can be flat, and its shape when viewed from the flat side where the metal powder is deposited is not particularly limited. The shape of the molded plate in plan view can be, for example, a polygon including a square or rectangle, a circle, an ellipse, etc. Usually, the thickness of the molded plate is almost the same throughout, but the thickness of the molded plate can be changed on the condition that the area where the metal powder is deposited can be made flat by downward pressing. From the viewpoint of production efficiency, the thickness of the molded plate is 30 mm or less. From the viewpoint of increasing the number of uses of the molded plate, the lower limit of the thickness of the molded plate is preferably 3 mm or more. The thickness of the molded plate may be in the range of 3 mm to 15 mm, or in the range of 3 mm to 8 mm. The surface area of ​​the molded plate is 36 cm² at the lower limit. 2 The dimensions should be at least the above (for example, 6cm x 6cm or larger). Also, the surface area of ​​the molded plate should typically be 15,000 cm² as the upper limit. 2 The following, and furthermore, 5000cm 2 The following may be used: In one embodiment, for example, the surface area is 4500 cm². 2 It can also be used for molded boards that are (for example, 90cm x 50cm).

[0022] (Area of ​​the area to be deposited) The area of ​​the deposition region on the surface of the molded plate where metal powder is deposited is not particularly limited, as long as there is enough space on the surface to press the molded plate downwards. Therefore, the area of ​​the deposition region where metal powder is deposited is smaller than the surface area of ​​the molded plate. The area of ​​the deposition region can be adjusted as appropriate according to the dimensions of the porous metal body.

[0023] (metal powder) While metal powders can be selected and used as appropriate, metal powders containing one or more selected from pure titanium powder, titanium alloy powder, steel powder (sometimes called iron powder), and iron alloy powder are preferred. Furthermore, it is also preferable that the metal powders consist of one or more selected from pure titanium powder, titanium alloy powder, steel powder, and iron alloy powder. Moreover, it is also preferable that the metal powders consist of one or more selected from pure titanium powder and titanium alloy powder. Pure titanium has a titanium content of 95% by mass or more. Since hydrogen can be reduced by sintering, pure titanium may contain hydrogen. Pure titanium may contain hydrogen, provided that the hydrogen content is 5% by mass or less. Titanium alloys are alloys of titanium with metals (alloy metals) such as Fe, Sn, Cr, Al, V, Mn, Zr, Mo, platinum group metals (Pt, Pd, Ru, etc.), Ni, and Pd. Specific examples include Ti-6-4 (Ti-6Al-4V), Ti-5Al-2.5Sn, Ti-8-1-1 (Ti-8Al-1Mo-1V), Ti-6-2-4-2 (Ti-6Al-2Sn-4Zr-2Mo-0.1Si), Ti-6-6-2 (Ti-6Al-6V-2Sn-0.7Fe-0.7Cu), T i-6-2-4-6(Ti-6Al-2Sn-4Zr-6Mo), SP700(Ti-4.5Al-3V-2Fe-2Mo), Ti-17(Ti-5Al-2Sn-2Zr-4Mo-4Cr), β-CEZ(Ti-5Al-2Sn- 4Zr-4Mo-2Cr-1Fe), TIMETAL555, Ti-5553(Ti-5Al-5Mo-5V-3Cr-0.5Fe), TIMETAL21S(Ti-15Mo-2.7Nb-3Al-0.2Si), TIMETAL Examples include LCB (Ti-4.5Fe-6.8Mo-1.5Al), 10-2-3 (Ti-10V-2Fe-3Al), Beta C (Ti-3Al-8V-6Cr-4Mo-4Cr), Ti-8823 (Ti-8Mo-8V-2Fe-3Al), 15-3 (Ti-15V-3Cr-3Al-3Sn), Beta III (Ti-11.5Mo-6Zr-4.5Sn), and Ti-13V-11Cr-3Al. In the above, the numbers preceding each alloying metal indicate the content (mass%). For example, "Ti-6Al-4V" refers to a titanium alloy containing 6 mass% Al and 4 mass% V as alloying metals. The shape of the metal powder is not particularly limited; for example, pulverized powder such as HDH powder may be used, or atomized powder with high circularity in plan view may be used. The particle size of the metal powder can be selected as appropriate, for example, 10 to 150 μm for D50, and more preferably 10 to 80 μm. Furthermore, a D50 of 10 to 45 μm for the metal powder is also preferable. Here, "D50" refers to the particle size at which the cumulative amount counted from the smallest particle size side reaches 50% of the total sample in the volume-based particle size distribution measured using a laser diffraction / scattering particle size analyzer for the powder sample. The same applies to the particle size D50 of the metal powder described later. The iron alloy may be an alloy of Fe with other metals (alloy metals) such as Ti, Si, Sn, Ni, Cr, Al, V, Mn, Zr, Nb, and Mo. Specific examples of such iron alloys include stainless steel.

[0024] <Thickness adjustment step> In the thickness adjustment step, the thickness of the deposited layer of metal powder deposited on the molded plate is adjusted. This thickness adjustment is usually performed in the manufacture of porous metal bodies in sheet form. However, if the molded plate used does not have a flat surface, the thickness variation of the manufactured porous metal body is reduced by adjusting the thickness of the deposited layer of metal powder on the molded plate while making the surface of the molded plate flat. Since the flatness of the surface of the molded plate may be lost with repeated use, for example, after the second use of the molded plate, the surface of the molded plate may be made flat in consideration of the shape of the molded plate. This process of making the surface of the molded plate flat may be the process described in the deposition step. Alternatively, this process of making the surface of the molded plate flat may be performed every time in the thickness adjustment step. The thickness of the metal powder deposit layer on the molded plate can be adjusted, for example, by using an applicator to flatten the top surface of the metal powder deposit layer on the molded plate, thereby forming it into a sheet and adjusting the thickness of the deposit layer. At this time, excess metal powder can also be removed from the surface of the molded plate. Therefore, in one embodiment, performing the thickness adjustment step reduces variations in the thickness of the porous metal body obtained in the sintering step.

[0025] Examples of methods for adjusting the thickness include the applicator method described above. The applicator only needs to consist of a pair of opposing side plates and a blade, such as a metal blade, positioned between the pair of side plates, and the width setting and clearance (thickness) setting of the applicator can be adjusted as appropriate. Commercially available applicators may be used as appropriate. This section describes an example of a method for adjusting the thickness of a metal powder deposition layer using an applicator. Note that the following example assumes that the shape of the molded plate, as observed from the flat side where the metal powder is deposited, is either square or rectangular. First, a molding plate with a metal powder deposition layer is placed on the horizontal surface of the base member, and at least a portion of the edge of the surface of the molding plate and the base member are clamped in a vise and a portion of the edge is pressed downward so that the surface of the molding plate becomes flat. Next, a pair of sleeve plates of the applicator are placed on the surface of the molding plate, and the width of the applicator is adjusted. Next, a certain clearance is formed between the metal blade and the surface of the molding plate. Then, while moving the pair of sleeve plates of the applicator relative to the surface of the molding plate, the metal blade is adjusted so that the thickness of the metal powder deposition layer becomes uniform. If the shape of the molding plate when viewed from the planar side is other than a square or rectangle, the thickness of the metal powder deposition layer can be adjusted by referring to the above description. That is, the shape of the molding surface can be adapted by appropriately combining the settings and movement direction of the applicator.

[0026] <Sintering step> The sintering step is performed after the deposition step, in which the metal powder on the molded plate is sintered. As a result, a porous metal body is obtained as a sintered body. The thickness of the deposited layer of metal powder has been adjusted in the thickness adjustment step described above. It is preferable to carry out the sintering using a heating furnace in order to facilitate atmosphere control during the sintering process. If pressure was applied to the surface of the molded plate, the pressure is usually released after the thickness adjustment step is completed. Thus, the molded plate and the layer of metal powder deposited on the molded plate are placed inside the heating furnace.

[0027] (heating furnace) A heating furnace is used for sintering the deposited metal powder, and is, for example, an electric heating furnace. During sintering in the heating furnace, multiple molded plates on which metal powder has been deposited can be stacked with spacers or the like in between. At this time, from the viewpoint of ensuring heat transfer from the heating furnace to the metal powder on each molded plate, it is preferable that the deposited layer of metal powder on the lower molded plate does not come into contact with the back surface of the upper molded plate. From a productivity standpoint, it is preferable to place 30 or more molded plates in the heating furnace and then sinter the metal powder on each molded plate. In other words, it is preferable to sinter the metal powder on 30 or more molded plates in a single heating cycle in the heating furnace.

[0028] (Sintering conditions) Metal powder sintering can be carried out under reduced pressure, such as a vacuum, or under an inert atmosphere. This prevents oxidation of the metal powder during sintering. Specifically, the degree of reduced pressure inside the heating furnace is 1.0 × 10⁻⁶ in absolute pressure. -2 The pressure can be reduced to below Pa, allowing sintering to be performed under reduced pressure. Alternatively, sintering can be performed in an inert atmosphere by filling the heating furnace with argon gas. Furthermore, the furnace temperature when sintering the metal powder is preferably 800°C or higher. From the viewpoint of the sinterability of the powder, the lower limit of the furnace temperature is more preferably 900°C or higher. From the viewpoint of manufacturing costs, the upper limit of the furnace temperature is typically 1200°C or lower. Furthermore, the duration for maintaining the furnace temperature is, for example, 1 to 6 hours.

[0029] <Properties of porous metal bodies> In one embodiment, the porosity of the porous metal body produced by the above-described method for manufacturing porous metal bodies can be appropriately set. This makes it possible to achieve permeability or liquid permeability according to the application.

[0030] Furthermore, the average thickness of the porous metal body may be, for example, 0.1 to 1.0 mm, 0.1 to 0.8 mm, or 0.1 to 0.5 mm. The following is an example of a method for measuring the average thickness. If the porous metal body is square or rectangular when viewed from above, draw two horizontal and two vertical lines on its surface to form a total of nine adjacent cells, ensuring that the area of ​​each cell is equal. Determine the thickness of the porous metal body in each cell using a film thickness gauge, and take the average value as the average thickness of the porous metal body. If the porous metal body is circular or elliptical when viewed from above, define a square or rectangle that circumscribes it and has the smallest area, define nine cells in that square or rectangle in the same manner as above, determine the thickness of the porous metal body in each cell using a film thickness gauge, and take the average value as the average thickness of the porous metal body.

[0031] Furthermore, in one embodiment, it is preferable that the variation rate α of the thickness variation of the porous metal body, as shown in the following formula (1), is, for example, 2.2 or less, and more preferably 1.2 or less. Note that the variation rate α tends to decrease as the surface of the molding plate on which the metal powder is deposited becomes flatter. For example, it is conceivable that there may be no significant difference in the thickness variation of the porous metal body between the first and second production runs. Therefore, for example, if a molding plate that has been used infrequently is used, the variation rate α may fall below 1.0 due to measurement errors, etc., depending on the B value shown in the following formula (1). α = B / A ... Equation (1) α: Rate of change in variation A: Thickness variation of porous metal bodies manufactured using unused molded sheets (i.e., first production batch) B: Thickness variation of porous metal bodies manufactured using the same molded sheet for the N+1 (N is an integer greater than or equal to 1)th time. The following are examples of methods for measuring variations in thickness. The difference between the maximum and minimum thickness values ​​among the nine cells obtained using the average thickness measurement method described above is defined as the thickness variation of the porous metal body. If, despite adjusting the thickness of the metal powder deposition layer while making the surface of the molded plate flat using a vise or the like in the thickness adjustment step, the variation rate α does not reach the desired value, that is, if the variation in the thickness of the manufactured porous metal body does not fall within the desired range, it is preferable to replace the molded plate being used. [Examples]

[0032] The present invention will be described in detail based on examples. The following examples are merely specific examples to facilitate understanding of the technical content of the present invention, and the technical scope of the present invention is not limited by these examples.

[0033] [Example 1] (Regarding the first production run) As shown in Table 1, in Example 1, a carbon molded plate (flat plate shape: length (L1) 110 mm × width (L2) 330 mm × thickness 25 mm) as shown in Figure 1 was prepared. Next, HDH titanium powder 110 (titanium purity 99.9% by mass or higher, D50: 13 μm) was deposited dry onto the surface 105 of the molded plate 100. At this time, HDH titanium powder 110 was not deposited in the area from the ends 102a and 102b parallel to the vertical direction to a position with a width W40 mm. To suppress variations in the thickness of the deposited layer of HDH titanium powder 110 on the molded plate 100, an applicator with a film thickness adjustment function (commercially available) was used. Next, the molded plate 100 with the deposited HDH titanium powder 110 was placed in an electric heating furnace, and sintering was performed in an inert atmosphere inside the electric heating furnace at a furnace temperature of 1000°C for a heating and holding time of 3 hours. After cooling, the sheet-like porous metal body was peeled off the molded plate 100. The average thickness of the obtained sheet-like porous metal body was measured according to the procedure described above, and the average thickness was found to be 0.2 mm.

[0034] (Regarding the 8th production run) Then, the production of a sheet-like porous metal body was repeated seven times using the same molded plate 100. In the eighth production of the sheet-like porous metal body, HDH titanium powder 110 was sintered according to the procedure shown in Figures 2(A) to (F). However, the illustrations in Figures 2(A) to (F) are approximate, and the sizes and other details shown may not be accurate. As shown in Figure 2(A), the molded plate 100 was placed on the horizontal surface 125a of the base member 125. Next, as shown in Figure 3, on the surface 105 of the molded plate 100, within the area where HDH titanium powder 110 was not deposited (a range of W40 mm from both ends 102a and 102b parallel to the vertical direction), the two corners 104 of one end 103a parallel to the horizontal direction of the molded plate 100 were clamped with a vise 120 so as to press downward toward the horizontal surface 125a of the base member 125. This operation improved the flatness of the surface of the molded plate 100, making it visually flat (Figure 2(B)). Next, as shown in Figure 2(C), HDH titanium powder 110 was dry-laid onto the surface 105 of the molded plate 100. Next, as shown in Figure 2(D), the applicator was moved longitudinally from the edge 103a side, which was clamped in the vise, toward the opposite edge 103b side, to adjust the thickness of the HDH titanium powder 110 layer to be uniform. Next, as shown in Figure 2(E), the vise 120 was removed from the molded plate 100 and the base member 125. After that, the molded plate 100 was placed in an electric heating furnace, the inside of the electric heating furnace was set to an inert atmosphere, the furnace temperature was 1000°C, and the heating and holding time was 3 hours. Then, as shown in Figure 2(F), the molded plate 100 was removed from the electric heating furnace, and the sheet-like porous metal body 115 was peeled off from the molded plate 100. The average thickness of the obtained sheet-like porous metal body was measured according to the procedure described above, and the average thickness was found to be 0.2 mm.

[0035] The thickness variation of the sheet-like porous metal body produced in the first batch and the sheet-like porous metal body produced in the eighth batch was measured according to the procedure described above, and the variation change rate α shown in formula (1) above was calculated. These results are shown in Table 2. The evaluation results shown in Table 2 are based on the following criteria. "**" and "***" in the evaluation results in Table 2 were judged as passing, and "*" was judged as failing. (Judgment criteria) ***: When the rate of variation α is 1.2 or less. ** : When the rate of variation α is greater than 1.2 and less than or equal to 2.2. * : When the rate of variation α exceeds 2.2.

[0036] [Comparative Example 1] As shown in Table 1, in Comparative Example 1, a sheet-like porous metal body was manufactured in the same manner as in Example 1 (first manufacturing). The manufacturing of the sheet-like porous metal body was then repeated eight times using the same molded plate 100. The thickness variation of the sheet-like porous metal body manufactured in the first manufacturing and the sheet-like porous metal body manufactured in the eighth manufacturing were measured according to the procedure described above, and the variation change rate α shown in formula (1) above was determined. These results are shown in Table 2.

[0037] [Example 2] As shown in Table 1, in Example 2, a sheet-like porous metal body was manufactured in the same manner as in Example 1, except that the thickness of the molded plate 100 was changed to 3 mm. That is, a vise was used in the eighth manufacturing step, as in Example 1. The thickness variation of the sheet-like porous metal body manufactured in the first step and the sheet-like porous metal body manufactured in the eighth step was measured according to the procedure described above, and the variation change rate α shown in formula (1) above was calculated. These results are shown in Table 2. In both the first and eighth manufacturing steps of Example 2, the average thickness of the obtained sheet-like porous metal body was 0.2 mm, similar to Example 1.

[0038] [Comparative Example 2] As shown in Table 1, in Comparative Example 2, a sheet-like porous metal body was manufactured in the same manner as in Example 2 (first manufacturing). The manufacturing of the sheet-like porous metal body was then repeated eight times using the same molded plate 100. The thickness variation of the sheet-like porous metal body manufactured in the first manufacturing and the sheet-like porous metal body manufactured in the eighth manufacturing were measured according to the procedure described above, and the variation change rate α shown in formula (1) above was determined. These results are shown in Table 2.

[0039] [Comparative Example 3] As shown in Table 1, in Comparative Example 3, a sheet-like porous metal body was manufactured in the same manner as in Example 1 (first manufacturing), except that the material of the molded plate 100 was changed to quartz. The manufacturing of the sheet-like porous metal body was repeated eight times using the same molded plate 100. The thickness variation of the sheet-like porous metal body manufactured in the first manufacturing and the sheet-like porous metal body manufactured in the eighth manufacturing were measured according to the procedure described above, and the variation change rate α shown in formula (1) above was determined. These results are shown in Table 2.

[0040] [Comparative Example 4] As shown in Table 1, Comparative Example 4 was carried out in the same manner as Example 1, except that the same molded plate 100 as in Comparative Example 3 was used. However, as shown in Figures 2(B) and 3, when the molded plate 100 and the base member 125 were clamped in the vise 120, the molded plate 100 cracked. Therefore, a sheet-like porous metal body could not be manufactured. For this reason, the results for Comparative Example 4 are not listed in Table 2.

[0041] [Table 1]

[0042] [Table 2]

[0043] [Discussion based on examples] A comparison of Example 1 and Comparative Example 1 revealed that the thickness variation of the sheet-like porous metal body 115 produced in the first batch in Example 1 was almost the same as the thickness variation of the sheet-like porous metal body produced in the first batch in Comparative Example 1. However, the thickness variation of the sheet-like porous metal body produced in the eighth batch in Example 1 was significantly smaller than the thickness variation of the sheet-like porous metal body produced in the eighth batch in Comparative Example 1. Furthermore, a comparison of Example 2 and Comparative Example 2 revealed that the thickness variation of the sheet-like porous metal body 115 produced in the first batch in Example 2 was almost the same as the thickness variation of the sheet-like porous metal body produced in the first batch in Comparative Example 2. However, the thickness variation of the sheet-like porous metal body produced in the eighth batch in Example 2 was significantly smaller than the thickness variation of the sheet-like porous metal body produced in the eighth batch in Comparative Example 2. Therefore, in Examples 1 and 2, it was confirmed that a porous metal body with suppressed thickness variation can be manufactured even when relatively thin molded plates are used multiple times. Thus, it is understood that it is useful to adjust the thickness of the deposited layer formed by depositing metal powder on the molded plate 100 while making the surface 105 of the molded plate 100 flat. Furthermore, the variation rate α obtained in Example 2 was smaller than the variation rate α obtained in Example 1. From these results, it is considered that the thinner the thickness of the molded plate 100, the more effective it is to adjust the thickness of the deposited layer formed on the molded plate 100 by depositing metal powder while making the surface 105 of the molded plate 100 flat. Furthermore, in Examples 1 and 2, since the thickness of the molded plate is 30 mm or less, even if multiple molded plates 100 are stacked in the heating furnace, they do not take up much space, and it can be inferred that a relatively large number of porous metal bodies can be produced in a single sintering treatment in the heating furnace.

[0044] In Comparative Example 4, a vise was used to flatten the surface of the molded plate, but the plate cracked because the quartz had relatively low flexibility. In other words, comparing the results in Examples 1-2 and Comparative Example 4, it can be inferred that, in terms of the number of uses, the carbon material of the molded plate allows for a longer lifespan for the molded plate. [Explanation of Symbols]

[0045] 100 molded plate 102a, 102b, 103a, 103b Edge 104 corners 105 Surface 110 HDH Titanium Powder 115 Sheet-like porous metal body 1.2 million force 125 Base component 125a Horizontal surface L1 Vertical L2 horizontal W width

Claims

1. A method for manufacturing a porous metal body, Made of carbon, with a thickness of 30 mm or less, and a surface area of ​​36 cm² for depositing metal powder. 2 The above-described molding plate is then subjected to a deposition step in which metal powder is deposited dry, After the deposition step, a sintering step is performed to sinter the metal powder on the molded plate. Perform the process including this multiple times. In the multiple steps described above, the same molded plate is used. Of the aforementioned multiple steps, at least one step further includes a thickness adjustment step between the deposition step and the sintering step, in which the thickness of the deposited layer of metal powder on the molded plate is adjusted while making the surface of the molded plate flat. A method for manufacturing a porous metal body, wherein in the thickness adjustment step, the pressing to flatten the surface of the molded plate is applied only to the molded plate.

2. The method for producing a porous metal body according to claim 1, wherein in the sintering step, the metal powder is sintered at a temperature of 800°C or higher.

3. The method for producing a porous metal body according to claim 1 or 2, wherein the metal powder comprises one or more selected from pure titanium powder, titanium alloy powder, steel powder, and iron alloy powder.

4. The method for producing a porous metal body according to claim 3, wherein the metal powder comprises one or more selected from pure titanium powder and titanium alloy powder.

5. The method for producing a porous metal body according to any one of claims 1 to 4, wherein the metal powder comprises one or more selected from pulverized powder and atomized powder.

6. The method for producing a porous metal body according to any one of claims 1 to 5, wherein the D50 of the metal powder is 10 to 150 μm.

7. The method for manufacturing a porous metal body according to any one of claims 1 to 6, wherein in the sintering step, 30 or more of the molded plates are placed in a heating furnace and the metal powder on each molded plate is sintered in the heating furnace.

8. The method for manufacturing a porous metal body according to any one of claims 1 to 7, wherein the average thickness of the porous metal body is 0.1 to 1.0 mm.

9. A method for manufacturing a porous metal body according to any one of claims 1 to 8, wherein the rate of variation change shown in the following formula (1) is 2.2 or less. α=B / A...Formula (1) α: Rate of change in variation A: Thickness variation of porous metal bodies manufactured using unused molded sheets (i.e., first production batch) B: Thickness variation of porous metal bodies manufactured using the same molded plate for the N+1 (N is an integer greater than or equal to 1)th time.

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