Metallic porous body, method for producing the same, and filter

Abstract

A porous metal body according to the present invention has a three-dimensional network skeleton, a polygonal bottom face, and a curved shape that extends from the bottom face towards an apex, the length of one side of the bottom face being 2-10 mm inclusive, and the height of the apex from the bottom face being 1-5 mm inclusive.

Description

[Technical Field]

[0001] This disclosure relates to a porous metal body, a method for manufacturing a porous metal body, and a filter. This application claims priority to Japanese Patent Application No. 2020-156399 filed on September 17, 2020, Japanese Patent Application No. 2020-163246 filed on September 29, 2020, and Japanese Patent Application No. 2020-169661 filed on October 7, 2020, and incorporates all of the contents of these Japanese applications by reference. [Background technology]

[0002] Sheet-like porous metal bodies with a three-dimensional mesh-like structure skeleton are used in a variety of applications, including filters, catalyst carriers, metal composites, and battery electrode plates. Celmet (registered trademark, manufactured by Sumitomo Electric Industries, Ltd.), a porous metal body made of nickel, is widely used in various industrial fields, for example, as electrodes for alkaline storage batteries such as nickel-metal hydride batteries, and as supports for industrial deodorizing catalysts.

[0003] The metal porous body can be produced by a so-called plating method. For example, the metal porous body can be produced by subjecting the surface of a skeleton of a resin porous body having a skeleton with a three-dimensional network structure to a conductive treatment, then electroplating the surface of the skeleton of the resin porous body, and then removing the resin porous body (see JP-A-05-031446 (Patent Document 1) and JP-A-2011-225950 (Patent Document 2)). For example, a polyurethane resin can be preferably used as the resin porous body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 05-031446 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-225950 Summary of the Invention

[0005] The metal porous body according to the present disclosure comprises: The bottom surface is polygonal and curved from the bottom surface to the top surface, The bottom surface has a side length of 2 mm or more and 10 mm or less, The height from the bottom surface to the top is 1 mm or more and 5 mm or less, It has a three-dimensional mesh-like skeleton. It is a porous metal body.

[0006] A metal porous body according to another embodiment of the present disclosure includes: The bottom surface is circular and the top surface is hemispherical, The bottom surface has a diameter of 2 mm or more and 10 mm or less, The height from the bottom surface to the top is 1 mm or more and 5 mm or less, It is a porous metal body with a three-dimensional mesh-like skeleton.

[0007] The method for producing a porous metal body according to the present disclosure includes: a step of cutting a porous metal substrate having a skeleton with a three-dimensional network structure, The metal porous body has a polygonal bottom surface and a curved shape from the bottom surface to the apex, or a circular bottom surface and a hemispherical shape from the bottom surface to the apex. A method for producing a porous metal body.

[0008] A filter according to the present disclosure is a filter comprising the metal porous body of the present disclosure. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a porous metal body according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is another schematic view of a porous metal body according to an embodiment of the present disclosure. [Figure 3] FIG. 3 is an example of a photograph of the bottom surface of a porous metal body according to an embodiment of the present disclosure. [Figure 4]FIG. 4 is an enlarged schematic view showing a cross section of a porous metal body according to an embodiment of the present disclosure. [Figure 5] FIG. 5 is a schematic diagram illustrating a state in which a porous metal body according to an embodiment of the present disclosure is filled in a housing portion of a filter. [Figure 6] FIG. 6 is a schematic diagram of a porous metal substrate having a skeleton with a three-dimensional network structure. [Figure 7] FIG. 7 is a diagram showing an example of a cut section of a porous metal substrate for producing the porous metal shown in FIG. [Figure 8] FIG. 8 is a schematic diagram showing the configuration of the filter produced in the example. [Figure 9] FIG. 9 is a schematic diagram showing the configuration of an apparatus for measuring the pressure loss of the filters produced in the examples and comparative examples. [Figure 10] FIG. 10 is a schematic diagram showing the configuration of a filter produced in a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Problem to be solved by this disclosure] When a metal porous body having a skeleton with a three-dimensional network structure as described above is produced by a plating method, it has been difficult to produce a thick metal porous body. The reason is that in the plating method, the plating film is gradually formed from the edges of the substrate in the thickness direction, and the plating film is formed later near the center in the thickness direction. Therefore, if the substrate is too thick, the plating film near the center in the thickness direction will be thin, and in extreme cases, the substrate will split into two near the center in the thickness direction after plating.

[0011] For this reason, when a metal porous body obtained by plating is used as, for example, a filter, it has been necessary to stack multiple metal porous bodies in the filter housing to ensure a sufficient thickness. However, as a result of extensive investigations by the present inventors, it has been found that when multiple metal porous bodies are stacked and used, if the first metal porous body becomes clogged, the pressure loss increases, and furthermore, the second and subsequent metal porous bodies may not be able to function adequately as a filter.

[0012] [Effects of this disclosure] Therefore, an object of the present disclosure is to provide a porous metal body that, when used as a filter, can suppress an increase in pressure loss and prolong the filter function.

[0013] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described. The metal porous body according to one embodiment of the present disclosure comprises: The bottom surface is polygonal and curved from the bottom surface to the top surface, The bottom surface has a side length of 2 mm or more and 10 mm or less, The height from the bottom surface to the top is 1 mm or more and 5 mm or less, It has a three-dimensional mesh-like skeleton. By adopting such a configuration, it is possible to provide a porous metal body that, when used as a filter, can suppress an increase in pressure loss and prolong the filter function.

[0014] A metal porous body according to another embodiment of the present disclosure includes: The bottom surface is circular and the top surface is hemispherical, The bottom surface has a diameter of 2 mm or more and 10 mm or less, The height from the bottom surface to the top is 1 mm or more and 5 mm or less, It has a three-dimensional mesh-like skeleton. By adopting such a configuration, it is possible to provide a porous metal body that, when used as a filter, can suppress an increase in pressure loss and prolong the filter function.

[0015] The metal porous body is The skeleton may contain nickel as a main component and one or more of chromium, tin, and cobalt as additive components. By using such a configuration, a metal porous body having excellent heat resistance and corrosion resistance can be provided.

[0016] The metal porous body is The average pore size may be 400 μm or more and 1000 μm or less. By adopting such a configuration, it is possible to provide a porous metal body having pores with a diameter suited to the size of particles to be collected.

[0017] A method for producing a porous metal body according to one embodiment of the present disclosure includes: a step of cutting a porous metal substrate having a skeleton with a three-dimensional network structure, The metal porous body has a polygonal bottom surface and a curved shape from the bottom surface to the apex, or a circular bottom surface and a hemispherical shape from the bottom surface to the apex. By configuring in this manner, it is possible to provide a method for producing a porous metal body that, when used as a filter, can suppress an increase in pressure loss and prolong the filter function.

[0018] A filter according to one embodiment of the present disclosure is a filter including the porous metal body of the present disclosure. By adopting such a configuration, it is possible to provide a filter that can maintain its filtering function for a long time.

[0019] [Details of the embodiments of the present disclosure] Specific examples of porous metal bodies and methods for manufacturing porous metal bodies according to embodiments of the present disclosure will be described in more detail. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0020] <Porous metal body> FIG. 1 shows an outline of an example of a metal porous body 10 according to an embodiment of the present disclosure. The metal porous body 10 has a polygonal bottom surface 21 that is curved from the bottom surface 21 to the apex 22. The bottom surface 21 may have a square or rectangular shape as long as the length of one side is 2 mm or more and 10 mm or less. The length of one side of the bottom surface 21 may be 2 mm or more and 8 mm or less, or 2.5 mm or more and 4.5 mm or less. The height from the bottom surface 21 to the apex 22 may be 1 mm or more and 5 mm or less, or 2 mm or more and 8 mm or less, or 2.5 mm or more and 4 mm or less. The height is defined as the length of the perpendicular line from the apex 22 to the bottom surface 21. Examples of polygonal shapes include a square, a pentagon, and a hexagon.

[0021] The porous metal body 10 shown in FIG. 2 has a circular bottom surface 21 and a hemispherical shape extending from the bottom surface 21 to the apex 22. The diameter of the bottom surface 21 may be 2 mm or more and 10 mm or less, or may be 2 mm or more and 8 mm or less, or 2.5 mm or more and 4.5 mm or less. The height from the bottom surface 21 to the apex 22 may be 1 mm or more and 5 mm or less, or may be 2 mm or more and 8 mm or less, or 2.5 mm or more and 4 mm or less. The circular bottom surface may be not only a perfect circle but also an ellipse. In the case of an ellipse, the average diameter of the major and minor axes is treated as the diameter. The height is defined as the length of the perpendicular line from the apex 22 to the bottom surface 21. The hemispherical shape may be not only a hemisphere but also a semi-elliptical sphere.

[0022] The porous metal body 10 has a skeleton with a three-dimensional network structure. Fig. 3 shows an enlarged photograph of the bottom surface 21 of the porous metal body 10. Fig. 4 shows an enlarged schematic diagram of a cross section of the porous metal body 10 shown in Fig. 3. The skeleton 11 of the porous metal body 10 is typically composed of a film 12 made of a metal or alloy. The interior 13 of the skeleton 11 is hollow. The pores 14 formed by the skeleton 11 are interconnected pores formed by cells modeled as a regular dodecahedron that are connected from the surface to the interior of the porous metal body 10.

[0023] The skeleton 11 of the metal porous body 10 may be formed by a film 12 made of a metal or alloy. Examples of metals that form the skeleton 11 include nickel, aluminum, and copper. Examples of alloys that form the skeleton 11 include alloys in which other metals are inevitably or intentionally added to the metal. Examples of such alloys include alloys that contain nickel as the main component and one or more additive components selected from the group consisting of chromium, tin, and cobalt, and examples of alloys of these components include NiCr, NiSn, and NiCo. This allows for the provision of a metal porous body with excellent heat resistance and corrosion resistance. Furthermore, the skeleton 11 may have a layered structure having two or more metal or alloy films 12 formed by plating the surface of the metal or alloy with another metal.

[0024] The skeleton 11 containing nickel as a main component means that nickel is the largest component of the components constituting the skeleton 11. In addition, in the metal or alloy film 12, the Cr content may be 10 mass % or more and less than 50 mass %. Similarly, the Sn content may be 5 mass % or more and 30 mass % or less, and the Co content may be 10 mass % or more and 50 mass % or less.

[0025] The metal porous body 10 can be accommodated in the filter accommodation section at a high filling rate by having the shape shown in Fig. 1 or Fig. 2. Fig. 5 shows a schematic diagram of the metal porous body 10 shown in Fig. 1 accommodated in the filter accommodation section 30. Note that the metal porous body having the shape shown in Fig. 2 (with a circular bottom surface) can accommodate a higher filling rate in the filter accommodation section than the metal porous body having the shape shown in Fig. 1 (with a square bottom surface).

[0026] A fluid containing the objects to be captured flows from the upstream side (the upper side of the paper in FIG. 5) to the downstream side (the lower side of the paper in FIG. 5). At this time, the objects to be captured in the fluid are caught in the pores 14 of the porous metal bodies 10 and captured. Some of the objects to be captured pass through the gaps between the porous metal bodies 10 and move from the upstream side to the downstream side, but if a sufficient amount of porous metal bodies 10 is filled in the storage section 30 of the filter, they will be captured in the pores 14 of the porous metal bodies 10 arranged downstream.

[0027] The average pore diameter of the metal porous body 10 may be appropriately changed depending on the size of the object to be collected when used as a filter. For example, the average pore diameter of the metal porous body 10 may be 400 μm or more and 1000 μm or less, 500 μm or more and 950 μm or less, or 600 μm or more and 900 μm or less.

[0028] The average pore diameter of the porous metal body 10 is defined by the following formula [1]: In formula [1], nc is the average number of pores 14 per inch (25.4 mm = 25,400 μm) obtained by observing at least 10 fields of view of the main surface of the porous metal body 10 using a microscope or the like. Average pore diameter = 25400 μm / nc Equation [1] The number of pores 14 is measured in accordance with the method for determining the number of pores (cell count) of a soft foam material according to JIS K6400-1:2004, Appendix 1 (reference).

[0029] The porosity of the metal porous body 10 is desirably such that, when the metal porous body 10 is used as a filter, it has excellent capture properties for the target substance and low pressure loss. The porosity of the metal porous body 10 may be, for example, 60% to 98%, 70% to 98%, or 90% to 98%. As will be described later, the metal porous body 10 is manufactured by cutting it out from a metal porous body substrate 20. In many cases, the porosity of the metal porous body substrate 20 immediately after manufacture is about 98%, so the metal porous body 10 can be cut out after adjusting the porosity by compressing the metal porous body substrate 20 in the thickness direction Z.

[0030] The porosity of the porous metal body 10 is defined by the following formula [2]. Porosity (%) = [1-{Mp / (Vp×dp)}]×100 Equation [2] Mp: Mass of porous metal body [g] Vp: Volume of the external shape of the porous metal body [cm 3 ] dp: Density of the metal constituting the porous metal body [g / cm 3 ]

[0031] Although the above description has been given of the case where the porous metal body 10 is used as a filter, the use of the porous metal body 10 is not limited to a filter. For example, by supporting a catalyst on the surface of the skeleton 11 of the porous metal body 10 and using it as a catalyst support, it is also possible to reform a target substance in a fluid. In this case, as in the case of using it as a filter, it is possible to prevent an increase in pressure loss and prolong the life of the catalyst function.

[0032] <Method of manufacturing porous metal body> A metal porous body substrate 20 as shown in FIG. 6 is prepared. The metal porous body substrate 20 has a skeleton 11 with a three-dimensional network structure and has an overall flat plate-like appearance. The porosity, average pore diameter, and other properties of the metal porous body substrate 20 may be the same as those required for the metal porous body 10. Like the metal porous body 10, the metal porous body substrate 20 may have a hollow skeleton with pores formed by the skeleton. The porosity and average pore diameter of the metal porous body substrate 20 are defined in the same way as those of the metal porous body 10 described above. As a metal porous body having a skeleton with a three-dimensional network structure, for example, Celmet (a metal porous body whose main component is Ni; "Celmet" is a registered trademark) manufactured by Sumitomo Electric Industries, Ltd. can be preferably used.

[0033] The porous metal substrate 20 prepared as described above can be cut to obtain the porous metal substrate 10 according to an embodiment of the present disclosure. FIG. 7 shows an outline of the process for cutting the porous metal substrate 20. The porous metal substrate 10 shown in FIG. 1 can be produced by cutting the flat porous metal substrate 20 in the thickness direction Z along the dashed line in FIG. 7 into a rectangular shape with a side length of 2 mm or more and 10 mm or less. The porous metal substrate 20, which has a hollow skeleton, is easily deformed when force is applied, so when it is cut, the cut portion is crushed, its thickness is reduced, and it is separated at the bottom. As a result, the center of the rectangle becomes the apex 22, from which the four sides of the bottom portion are sloped, resulting in a curved shape.

[0034] To manufacture the porous metal body 10 shown in Fig. 2, the porous metal body substrate 20 may be punched with, for example, a blade into a circle having a diameter of 2 mm or more and 10 mm or less. As a result, the circumferential portion where the blade is pressed is crushed and thinned, and the porous metal body substrate 20 is cut off at its bottom surface. The cut porous metal body 10 has a circular center portion as the apex 22, which slopes from there toward the circumferential portion of the bottom surface, resulting in a hemispherical shape.

[0035] The thickness of the metal porous body substrate 20 may be less than 3 mm. This allows for the preparation of a metal porous body substrate in which the metal or alloy film 12 constituting the skeleton near the center of the thickness direction of the metal porous body substrate is sufficiently thick. To manufacture a metal porous body 10 having a height of 3 mm or more from the bottom surface 21 to the top surface 22, multiple metal porous body substrates 20 having a thickness of less than 3 mm can be stacked in the thickness direction and then cut. When the metal porous body substrates 20 are cut in a stacked state, for example, the skeletons at the portion where a blade is applied are crushed and entangled, thereby bonding the metal porous body substrates 20 together. In the metal porous body 10 according to the embodiment of the present disclosure, the size of the bottom surface 21 is small relative to the height from the bottom surface 21 to the top surface 22, so the adhesive strength due to the entanglement of the skeletons at the peripheral edges is sufficient, and the metal porous body substrates 20 can be used in an integrated state without peeling. The thickness of the metal porous body substrate 20 can be measured, for example, using a digital thickness gauge. [Example]

[0036] The present disclosure will be described in more detail below based on examples, but these examples are merely illustrative and the porous metal bodies of the present disclosure are not limited thereto. The scope of the present disclosure is defined by the claims, and includes all modifications within the meaning and scope of the claims.

[0037] [Example 1] A porous nickel body (Celmet #4 manufactured by Sumitomo Electric Industries, Ltd.) with a thickness of 2.0 mm, a porosity of 93%, and an average pore diameter of 850 μm was prepared as a porous metal substrate having a skeleton with a three-dimensional network structure. The porous nickel body was cut using a cutting tool to have a square shape with a base dimension of 4 mm x 4 mm, producing porous metal body No. 1 with the shape shown in Figure 1.

[0038] [Example 2] Metal porous body No. 2 having the shape shown in Figure 2 was produced in the same manner as in Example 1, except that in the manufacturing method described in Example 1, the nickel porous body was cut with a round blade so that it had a circular bottom surface with a diameter of 2.5 mm.

[0039] [Example 3] Metal porous body No. 3 having the shape shown in Figure 1 was produced in the same manner as in Example 1, except that in the manufacturing method described in Example 1, two nickel porous bodies were stacked in the thickness direction Z and then cut in that state using a cutting tool.

[0040] [evaluation] As shown in Figure 8, filter No. 1 was prepared by placing porous metal body No. 1 in the filter's housing. Powder with a diameter of 5 μm (JIS Z 8901 test powder type 8) was prepared as the object to be collected. This powder was passed through filter No. 1 together with an airflow (dry air). The airflow rate was 1 L / min, and the passage time was 5 minutes. The powder ratio in the airflow was 5 mg / m 2 Figure 9 shows an outline of the configuration of the apparatus used to measure the pressure drop of filter No. 1. In this apparatus, dry air and powder were prepared in a supply container 41, and air was passed through filter No. 1 via stainless steel piping 42. The airflow rate was measured with a flowmeter 44 and adjusted to 1 L / min using a regulator 43. The pressure drop caused by the airflow passing through filter No. 1 housed in the filter housing 30 was measured with a pressure gauge 45 and a differential pressure gauge 46. The length of the filter housing 30 was 10 cm, and the pressure drop was expressed as the pressure drop per length. The powder that passed through filter No. 1 was collected in a collection container 47. The collection efficiency was then calculated. The pressure drop 30 seconds after the start of airflow was 22 Pa / cm. This was the first test, and second and third tests were conducted in the same manner. As a result, no increase in pressure drop was observed. After the airflow had finished, filter No. 1 was divided into three equal parts from upstream to downstream, into regions A through C, as shown in Figure 8. The porous metal body No. 1 located near the center of each region was removed and the amount of powder trapped in the pores was observed. The results showed that there was almost no difference in the amount of powder trapped in the pores of the porous metal body No. 1 located near the center of each of regions A, B, and C. The results are shown in Table 1.

[0041] Filters No. 2 and No. 3 were prepared and evaluated using porous metal body No. 2 and porous metal body No. 3 in the same manner as porous metal body No. 1. The initial pressure loss was 20 Pa / cm when porous metal body No. 2 was used, and 22 Pa / cm when porous metal body No. 3 was used. Similar tests were conducted twice, but no increase in pressure loss was observed. For porous metal body No. 2 and porous metal body No. 3, there was almost no difference in the amount of powder trapped in the pores of the porous metal body located near the center of each of regions A, B, and C. The results are shown in Table 1.

[0042] [Comparative Example] For comparison, the porous metal substrate prepared in Example 1 was stacked and housed in the housing of a filter as shown in Figure 10 to produce Filter No. 4. Evaluation was performed in the same manner as in Example 1, and the pressure loss was 45 Pa / cm. Similar second and third tests were performed consecutively, and the pressure loss increased with each test. The amount of powder trapped in the pores of the porous metal substrate located near the center of each of regions A, B, and C was examined, and it was found that there was a large distribution of the collection positions, with most of the powder being trapped and clogging in region A, and almost no powder being observed in regions B and C. The results are shown in Table 1.

[0043] [Table 1] [Explanation of symbols]

[0044] 10. Porous metal 11 Skeleton 12 Metal or alloy films 13 Inside 14 Pore 20 Metal porous base material 21 Bottom 22 Top 30 Filter housing 41 Supply container 42 Stainless steel piping 43 Regulator 44 Flow meter 45 Pressure gauge 46 Micro-differential pressure gauge 47 Collection container Z thickness direction A, B, C area

Claims

1. The bottom surface is polygonal and curved from the bottom surface to the top surface, The bottom surface has a side length of 2 mm or more and 10 mm or less, The height from the bottom surface to the top is 1 mm or more and 5 mm or less, It has a three-dimensional mesh-like skeleton. Porous metal.

2. The bottom surface is circular and the top surface is hemispherical, The bottom surface has a diameter of 2 mm or more and 10 mm or less, The height from the bottom surface to the top is 1 mm or more and 5 mm or less, It has a three-dimensional mesh-like skeleton. Porous metal.

3. the skeleton contains nickel as a main component and one or more of chromium, tin, and cobalt as an additive component; The metal porous body according to claim 1 or 2.

4. The average pore diameter is 400 μm or more and 1000 μm or less. The metal porous body according to any one of claims 1 to 3.

5. a step of cutting a porous metal substrate having a skeleton with a three-dimensional network structure, The metal porous body has a polygonal bottom surface and a curved shape from the bottom surface to the apex, or a circular bottom surface and a hemispherical shape from the bottom surface to the apex. A method for manufacturing a porous metal body.

6. A filter comprising the metal porous body according to any one of claims 1 to 4.

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