JP7634869B2 - Porous metal joint and method for producing same - Google Patents

Description

The present invention relates to a porous metal bonded body formed by bonding porous metal members together and a method for manufacturing the same.

Conventional inventions of this type include a method for joining filter materials, as described in Patent Document 1. In this joining method, the ends of two metal foam filter substrates with numerous interconnecting pores are compressed and densified, and then the densified ends are overlapped and the overlapping portions are welded.

JP 2005-144380 A

The above conventional technology aims to ensure joint strength by welding high-density areas, but this requires a lot of labor, and there is a need to improve productivity.

In view of the above problems, the present invention has the following configuration.
A porous metal joint, comprising at least a portion of two porous metal members each having a large number of micro-depressions and micro-protrusions on the surface thereof, which are overlapped with each other and have a joint portion pressed against each other in the direction of the overlapping, wherein the micro-protrusions of one of the porous metal members are inserted into the micro-depressions of the other of the porous metal members at the joint portion, and the micro-protrusions and the micro-recesses are plastically deformed in a direction intersecting the direction of the overlapping and in random directions.

The present invention is configured as described above, so sufficient joint strength can be obtained without welding, and productivity is also good.

1 is a perspective view showing an example of a porous metal joint according to the present invention. FIG. 2 is a cross-sectional view taken along line (II)-(II) in FIG. 3A and 3B are cross-sectional views showing the manufacturing procedure of the porous metal joint at the same cross-sectional position as in FIG. 2, in which (a) shows the state in which the opposing ends of two porous metal members are overlapped, and (b) shows the state in which the overlapped parts are pressed together. This is a micrograph of the cross section of two porous metal members overlapping each other without pressing them together, magnified by 50. Of the two porous metal members, only the upper porous metal member shown in the figure is dyed with a dye. This is a micrograph of the cross section of two pressed porous metal members, magnified by 50. Of the two porous metal members, only the upper one shown in the figure has been dyed with a dye. 6 is a diagram obtained by tracing the lower edge line of the upper porous metal member visible in FIG. 5 and the upper edge line of the lower porous metal member visible in FIG. 5 . FIG. 4 is a vertical cross-sectional view showing another example of a porous metal joint according to the present invention, in which portions other than the overlapping portions are also pressure-welded. 8A and 8B show another example of a porous metal bonded body according to the present invention, in which (a) is a plan view and (b) is a sectional view taken along the line (VIIIb)-(VIIIb) in (a). 4A and 4B are perspective views showing the steps of manufacturing the porous metal joint, in which FIG. 4A shows a porous metal member having cuts formed therein, and FIG. 4B shows the porous metal member in a state where a portion between adjacent cuts has been bent. 1A is an oblique view showing the manufacturing procedure of the porous metal joint, in which (a) shows the state in which the pressure-welded piece portions of two porous metal members are opposed to each other, and (b) shows the state in which the pressure-welded piece of one porous metal member is overlapped with the pressure-welded piece of the other porous metal member. 1A and 1B show another example of a porous metal bonded body according to the present invention, in which (a) is a plan view and (b) is a longitudinal sectional view taken along the line (XIb)-(XIb) in (a). 11(b) are cross-sectional views showing the manufacturing procedure of the porous metal joint at the same cross-sectional position as FIG. 11(b), where (a) shows the state in which the opposing ends of two porous metal members are overlapped, and (b) shows the state in which the overlapped parts are pressed together. 1 is a diagram and a table showing the results of a comparative experiment on a porous metal joint according to the present invention.

This embodiment discloses the following features.
The first feature is that the joint has at least a portion of two porous metal members having a large number of micro-convex portions and micro-convex portions on their surfaces overlapped and pressed together, and at the joint, the micro-convex portions of one of the porous metal members are inserted into the micro-convex portions of the other of the porous metal members, and these micro-convex portions and micro-convex portions are plastically deformed in a direction intersecting the overlapping direction (see Figures 1 to 13).

The second feature is that in the joint, a large number of the micro-projections and the micro-recesses are plastically deformed in random directions that intersect the overlapping direction (see Figures 5 and 6).

The third feature is that the joint is a part of the two porous metal members, and the joint and the part adjacent to the joint have approximately the same thickness in the overlapping direction (see Figure 7).

The fourth feature is that the two porous metal members are each a plate-shaped member, and the joint is a portion where the opposing end sides of the two porous metal members are overlapped and pressure welded together (see Figures 1 to 3, 7 to 8, and 11 to 12).

The fifth feature is that multiple notches are provided at one end of each of the porous metal members at intervals in the extension direction of the one end, and adjacent notches form pressure-welded pieces, and at the joint, multiple pressure-welded pieces in one of the porous metal members and multiple pressure-welded pieces in the other of the porous metal members are alternately stacked and pressure-welded in the extension direction (see Figures 8 to 10).

The sixth feature is that the joint has a convex portion including many of the micro recesses and micro protrusions on one of the overlapping surfaces that constitute the overlapping portion of the two porous metal members, and a concave portion including many of the micro recesses and micro protrusions and fitting into the convex portion on the other overlapping surface (see Figures 11 and 12).

The seventh feature is that the filter is constructed by forming the two porous metal members from a porous metal material with continuous pores.

The eighth feature includes a process of overlapping one of the porous metal members with the other of the porous metal members, and a process of pressing both of these porous metal members from both sides in the overlapping direction to form the joint (see Figures 3 and 12).

The ninth feature of the porous metal member is that the porous base material is subjected to a conductive treatment, then electroplated, and then the porous base material is removed.

<First embodiment>
Next, specific examples of the porous metal bonded body having the above-mentioned characteristics and the method for producing the same will be described in detail with reference to the drawings.

The porous metal joint A shown in FIG. 1 is made by overlapping and pressing at least a portion (in the illustrated example, the opposing ends) of two porous metal members 1 and 2, each of which has a large number of micro recesses a1 and micro protrusions a2 on its surface, to form a joint 10.

Each of the porous metal members 1 and 2 before pressure welding is formed by subjecting a porous base material (not shown) mainly composed of nickel (Ni) to an electrically conductive treatment, then electroplating, and then removing the porous base material, and has numerous pores a (see FIG. 4 ) therein. The numerous pores a are continuous pores that communicate with adjacent pores.
Each of the porous metal members 1 and 2 before pressure welding has 26 to 34 pores per inch and an average pore diameter of 0.85 mm.

The porous metal members 1 and 2 manufactured by the above-mentioned manufacturing method are different from sintered porous metal bodies, which are obtained by applying a mixture of fine metal powder and a solvent to a foamed resin and then baking (sintering). The inventors of the present application have experimentally confirmed that when the sintered porous metal bodies are pressed together to create a joint with approximately the same external shape, depending on the pressing strength, the mesh structure is destroyed and the base material crumbles like ash, making it impossible to obtain the same joint strength as the porous metal joint A.

There are various processing requirements for the application products of the porous metal bonded body A, such as a large-area filter in which a plurality of base materials are connected to each other. Therefore, a technology is desired for the porous metal bonded body A that can be easily processed without increasing the number of work steps and with less destruction of the three-dimensional mesh structure.
After much trial and error, the inventors of the present application have discovered that by creating porous metal members 1 and 2 using the above-mentioned manufacturing method with nickel as the main component and pressing these porous metal members 1 and 2 together, the metal at the joint 20 does not become brittle and crumble, sufficient joint strength can be obtained, and the workability is also excellent.

On the front and back surfaces of each porous metal member 1, 2, numerous minute recesses a1 and minute protrusions a2, consisting of parts of the pores a and parts of the walls surrounding the pores a, are exposed.

Each of the porous metal members 1 and 2 in the above configuration is formed into a predetermined shape (in the illustrated example, a rectangular flat plate shape).

The procedure for joining the two porous metal members 1, 2 will be described in detail as follows: first, the opposing ends of one porous metal member 1 and the other porous metal member 2 are overlapped on the flat surface of the lower mold M1 (see Figure 3).
This overlapping portion is pressed by being sandwiched from both sides in the overlapping direction (top and bottom directions in the illustrated example) between an upper mold M2 and a lower mold M1, thereby forming a compressed and integrally joined joint 10.
In this joined state, a concave impression 10a is formed on the upper surfaces of the two porous metal members 1 and 2 by the upper die M2.

The lower mold M1 is made of a hard metal material and has a flat upper surface for receiving the joint 10. For example, a base plate with a flat upper surface can be used as the lower mold M1.

The upper mold M2 is made of a hard metal material, and the lower end surface that presses the joint 10 from above is formed into a rectangular flat surface. The upper mold M2 is generally configured into, for example, a rectangular parallelepiped shape.

In the upper die M2, the vertical dimension of the lower end portion M2a is set to a length including the widthwise dimension W1 of the porous metal members 1, 2 (see FIG. 1).
The horizontal dimension of the lower end portion M2a is set to a length including an overlapping portion W2 (see FIG. 3(b)) in the joint portion 10.

At the joint 10, the metal parts constituting the pores a, the minute recesses a1, the minute protrusions a2, etc. are compressed and deformed in various directions (see Figure 5).

In particular, if we look at the structure near the boundary between one porous metal member 1 and the other porous metal member 2 at the joint 10, the micro-projections a2 of one porous metal member 1 (or 2) enter or fit into the micro-recesses a1 of the other porous metal member 2 (or 1), and these micro-projections a2 and micro-recesses a1 are plastically deformed in directions that are perpendicular to the overlapping direction and are random.

Here, the "overlapping direction" refers to the direction in which one of the two porous metal members 1, 2 is overlapped with the other, and in the example shown in Figure 2, it is the up-down direction.

The "direction intersecting the overlapping direction" includes a direction perpendicular to the overlapping direction, a direction intersecting the overlapping direction without being perpendicular, and the like.
More specifically, this intersecting direction includes the arrangement direction of the two porous metal members 1, 2 (left-right direction in Figure 2), a direction intersecting this arrangement direction (depth direction in Figure 2), and an inclined direction relative to these arrangement directions and depth directions.

The term "random direction" means that the direction in which the numerous minute protrusions a2 and minute recesses a1 undergo plastic deformation is not a regular direction (for example, the same direction, etc.).
That is, the direction of the plastic deformation includes many directions, such as one or the other of the arrangement directions, the depth direction or the front direction which is the opposite direction, and the inclination direction.

The plastic deformation may take the form of a micro-projection a2 or a micro-recess a1 deforming in only one of the intersecting directions, or of expanding or contracting in both the intersecting directions.

FIG. 5 is a microscopic image of a vertical cross section of the joint 10 in one example of the porous metal joint A having the above-mentioned configuration.
6 is a diagram in which the lower edge line of the porous metal member 1 seen in FIG. 5 and the upper edge line of the porous metal member 2 seen in FIG. 5 are traced.
These figures show that when the micro-convex portion a2 of one porous metal member 1 (or 2) enters the micro-concave portion a1 of the other porous metal member 2 (or 1), multiple areas can be seen where these micro-convex portions a2 and micro-concave portions a1 are plastically deformed in a direction intersecting the overlapping direction.

The relationship between the micro-protrusion a2 and the micro-recess a1 that fits into this micro-protrusion a2 can be confirmed as being fitted together with almost no gap, fitted together with a partial gap, fitted together in a biting manner, fitted together in a meshing manner, etc.

The thickness t of the joint 10 after compressive deformation is preferably within a range of 20 to 40% of the thickness T of each porous metal member 1 (or 2) before compressive deformation. In other words, if it is below the lower limit of this range, the deformation of the joint 10 becomes excessive, and there is a risk of a decrease in strength due to the occurrence of cracks, etc. On the other hand, if it exceeds the upper limit of this range, there is a risk of a significant decrease in the bonding strength of the joint 10.
In one example of this embodiment, the thickness t is set to about ⅓ of the thickness T.

Therefore, according to the porous metal joint A having the above-mentioned configuration, the micro recesses a1 and micro protrusions a2 of one porous metal member 1 and the micro recesses a1 and micro protrusions a2 of the other porous metal member 2 are intricately engaged with each other as described above, so that sufficient joint strength can be obtained even without welded parts, and productivity is also good.
Moreover, in the joint 10, although the internal continuous pores a and the minute recesses a1 on the surface are compressed to reduce the gaps, they are not clogged with molten material due to welding or the like, and therefore remain breathable.
Therefore, the porous metal joint A can be used as various filters such as kitchen oil filters, filters for industrial air conditioners, and mist collectors.

<Second embodiment>
Next, another embodiment of the present invention will be described. Note that the porous metal bonded body and the manufacturing method thereof described below are partially modified from the porous metal bonded body A and the manufacturing method thereof described above, and therefore the modified parts will be mainly described in detail.

The porous metal bonded body B shown in Figure 7 is the porous metal bonded body A described above, configured such that the joint 10 and the portion adjacent to the joint 10 have approximately the same thickness in the overlapping direction.

In more detail, this porous metal joint B is sandwiched and pressed from both sides in the overlapping direction by a lower die (not shown) and an upper die (not shown) having a width including the overlapping width W2 of the joint 10, so that the thickness t of the joint 10 and the thicknesses t', t' of the portions adjacent to both sides of the joint 10 become approximately the same.

Therefore, the porous metal bonded body B shown in FIG. 7 has substantially the same effect as the porous metal bonded body A, and since there is almost no difference in level between the joint 10 and the adjacent part, stress concentration due to differences in level or corners does not occur, and the design is also excellent.

As another manufacturing method, it is possible to separately compress the joint 10 and the portion adjacent to the joint 10 to produce a porous metal joint B with almost no steps.

<Third embodiment>
A porous metal joint C shown in FIGS. 8( a ) and 8 ( b ) is obtained by replacing the joint portion 10 in the porous metal joint A with a joint portion 20 .

The manufacturing procedure for this porous metal joint C will be described. First, a plurality of notches 1a, 2a are formed at intervals on one end side of each of the porous metal members 1, 2 before pressure welding in the extension direction of this one end (in other words, in the width direction of each of the porous metal members 1, 2) (see FIG. 9(a)).
Next, as shown in FIG. 9(b), the spaces between adjacent notches 1a, 1a (2a, 2a) are alternately bent in one direction and the other in the thickness direction by a dedicated jig (not shown) or the like, to form a plurality of rectangular, flat pressure-welded pieces 1b (2b).

Next, the multiple pressure-welded pieces 1b of one porous metal member 1 and the multiple pressure-welded pieces 2b of the other porous metal member 2 are alternately overlapped in the extension direction of the one end. Then, this overlapping portion is sandwiched and pressed between the above-mentioned lower mold M1 and upper mold M2, whereby it is compressed and deformed and integrally joined to form a joint 20.
In this joined state, a concave impression 20a is formed on the upper surfaces of the two porous metal members 1 and 2 by the upper die M2 (see FIG. 8(b)).

In the joint 20 formed as described above, between the overlapping pressure-welded pieces 1b, 2b, the micro-projections a2 of one porous metal member 1 (or 2) are inserted into the micro-recesses a1 of the other porous metal member 2 (or 1), and these micro-projections a2 and micro-recesses a1 are plastically deformed in directions that are perpendicular to the overlapping direction and are random.

Therefore, according to the porous metal joint C illustrated in Figures 8(a) and (b), substantially the same effect as the porous metal joint A can be obtained, and the joining strength between the two porous metal members 1 and 2 can be further improved by the alternating interlocking of the multiple pressure-welding pieces 1b and 2b and the contact between the side ends of the pressure-welding pieces 1b and 2b.
In particular, when attempting to obtain a metal molded product having a curved surface by joining base materials, the bonding strength of the joints is a concern. However, with the porous metal joint C, even in the case of a metal product having curved surfaces at the joints, the joint strength can be kept relatively high due to the interlocking structure described above, etc.

<Fourth embodiment>
The porous metal bonded body D shown in Figures 11(a) and (b) is obtained by replacing the bonding portion 10 in the porous metal bonded body A with a bonding portion 30, and is formed by replacing the upper mold M2 in the manufacturing method of the porous metal bonded body A with an upper mold M3 (see Figure 3).

The manufacturing procedure for the porous metal bonded body D will be described in detail below. First, the opposing ends of one porous metal member 1 before pressure welding and the other porous metal member 2 before pressure welding are overlapped (see FIG. 12(a)). This process is the same as the manufacturing procedure for the porous metal bonded body A described above.

Next, the overlapping portions of the ends are pressed by a plurality of upper dies M3 and a lower die M1 from both sides in the overlapping direction (in the illustrated example, from above and below). Through this process, the overlapping portions are compressed and integrally joined to form a joint 30.
In this joined state, a plurality of concave impressions 30a are formed on the upper surfaces of the two porous metal members 1, 2 by the plurality of upper dies M3.

Each upper die M3 is formed in a generally cylindrical shape extending in the vertical direction, and the peripheral edge of the flat portion at the lower end is chamfered into a convex curved surface (see FIG. 12(b)).
Multiple upper molds M3 are provided in the arrangement direction of the two porous metal members 1, 2 (two in the left-right direction in the example of Figure 11), and multiple upper molds M3 are also provided in the width direction of the porous metal members 1, 2 (five in the example of Figure 11).
These upper dies M3 are connected at their upper ends and move up and down as a unit.

In the compressively deformed joint 30, a plurality of convex portions 31 including a large number of minute recesses a1 and minute protrusions a2 are formed on one of the overlapping surfaces constituting the overlapping portion of the two porous metal members 1, 2 (see Figure 11 (b)).
Further, on the other mating surface, a plurality of concave portions 32 including a large number of minute recesses a1 and minute protrusions a2 are formed so as to fit into the respective protrusions 31.

At the joint 30, between the vertically fitted convex and concave portions 31 and 32, the minute convex portion a2 of one porous metal member 1 (or 2) is inserted into the minute concave portion a1 of the other porous metal member 2 (or 1), and these minute convex portions a2 and minute concave portions a1 are plastically deformed in directions that are intersecting with the overlapping direction and that are random.

Accordingly, the porous metal bonded body D shown in Figures 11(a) and (b) has substantially the same effect as the porous metal bonded body A, and the horizontal movement of the porous metal members 1 and 2 is restricted by the fit and pressure contact between the convex portion 31 and the concave portion 32, thereby further improving the bonding strength between the two porous metal members 1 and 2.

<Results of the comparative experiment>
Next, the results of a tensile strength test performed on the porous metal joint having the above-mentioned structure will be described (see FIG. 13).
In this experiment, for each of Examples 1 to 4 and Comparative Example, two porous metal members 1 and 2 were pulled apart at a pulling speed of 10 mm/min, and the tensile strength was measured. Note that this experiment was performed using a unique test method based on JIS K6850.

In this experiment, for each of Examples 1 to 4 and the Comparative Example, 10 test specimens each having a length and width dimension of 40 mm×width 150 mm and plate thicknesses T of 2 mm, 5 mm, and 10 mm were measured, and the average tensile strength was calculated.
In each test specimen, the thickness t of the joint 10 after compressive deformation was set to about ⅓ of the thickness T of each of the porous metal members 1 and 2 before compressive deformation.
The pressure applied when compressing the overlapping portions of the porous metal members 1 and 2 to form the joint 10 was 5 MPa.

Example 1 has the basic structure of the porous metal joint A.
Example 2 has the basic structure of the porous metal joint C.
Example 3 has the basic structure of the porous metal joint D.

Example 4 combines the basic structures of both porous metal bonded body C and porous metal bonded body D. In other words, Example 4 is a porous metal bonded body C (see FIG. 8) having multiple pressure-welded pieces 1b, 2b, to which multiple convex portions 31 and concave portions 32 (see FIG. 11) are formed.

In the comparative example, the overlapping portions of the porous metal member 1 and the porous metal member 2 facing each other were pressed and compressed with a flat die, and then spot-welded in two places. The spot-welding conditions were 9 cycles of current application, a current of 7000 A, and a pressure of 0.25 MPa.

The measurement results of the tensile strength are shown in the table of FIG.
That is, at a plate thickness T of 2 mm, Examples 1 to 4 were all slightly smaller than the comparative example.
At a plate thickness T of 5 mm, Examples 1, 2, and 4 were larger than the comparative example, and Example 3 was slightly smaller than the comparative example.
At a plate thickness T of 10 mm, Examples 3 and 4 were larger than the Comparative Example, and Examples 1 and 2 were slightly smaller than the Comparative Example.

Based on these results, it can be said that in Examples 1 to 4, if the plate thickness T is appropriately selected, a tensile strength equal to or greater than that of spot welded parts can be obtained.

<Other Modifications>
According to the above embodiment, the number of pores per inch and the average pore diameter are approximately the same in one porous metal member 1 and the other porous metal member 2, but as another example, it is also possible to make the number of pores and/or the average pore diameter different between the porosity of one porous metal member and the other porous metal portion.

In addition, in the above embodiment, the thickness of one porous metal member 1 and the thickness of the other porous metal member 2 are approximately the same, but as another example, the thickness of one porous metal member can be different from that of the other porous metal member.

In addition, according to the above embodiment, a portion of one side of the porous metal member 1 and a portion of one side of the porous metal member 2 are overlapped and pressed together, but as another example, it is also possible to overlap and press together the entire surface of one side of the porous metal member 1 and the entire surface of one side of the porous metal member 2.

In addition, in the above embodiment, the shape of the pressure-welded portion can be a shape other than the flat surface or circle described above. In other words, by changing the shape of the upper die, the shape of the pressure-welded portion can be, for example, a polygonal shape such as a triangle or hexagon, a specific figure shape such as a star, a character shape, etc.

In addition, in the above embodiment, the overlapping portions of the porous metal member 1 and the porous metal member 2 are not welded, and sufficient joint strength is obtained only by the pressure welding described above. As another example, the overlapping portions can be welded in addition to being pressure welded as described above.

Furthermore, the present invention is not limited to the above-mentioned embodiments, and can be modified as appropriate without departing from the spirit and scope of the present invention.

1, 2: Porous metal member 1a, 2a: Cut 1b, 2b: Press-fit piece 10, 20, 30: Joint 31: Convex 32: Concave A to D: Porous metal joint M1: Lower die M2, M3: Upper die a: Pore a1: Micro recess a2: Micro projection

Claims (9)

At least a portion of two porous metal members having a large number of minute recesses and minute protrusions on the surface are overlapped with each other, and a joint portion is provided which is pressure-welded in the overlapping direction ,
A porous metal joint, characterized in that, at the joint, the micro-convex portions of one of the porous metal members are inserted into the micro-concave portions of the other of the porous metal members, and these micro-convex portions and micro-concave portions are plastically deformed in directions that are perpendicular to the overlapping direction and that are random . The joint has two porous metal members each having a large number of minute recesses and minute protrusions on its surface, and at least a portion of the two porous metal members are overlapped and pressure-welded together,
a porous metal joint in which, at the joint, the microprojections of one of the porous metal members are inserted into the microdepressions of the other of the porous metal members, and the microprojections and the microdepressions are plastically deformed in a direction intersecting the overlapping direction,
The two porous metal members are each a plate-like member, and the joint portion is a portion where opposing end sides of the two porous metal members are overlapped and pressure-welded to each other,
A plurality of notches are provided at intervals in an extension direction of one end of each of the porous metal members, and a pressure-welded piece portion is formed between adjacent notches,
A porous metal joint, characterized in that at the joint, a plurality of the pressure-welded piece portions of one of the porous metal members and a plurality of the pressure-welded piece portions of the other of the porous metal members are alternately stacked and pressure-welded in the extension direction . The joint has two porous metal members each having a large number of minute recesses and minute protrusions on its surface, and at least a portion of the two porous metal members are overlapped and pressure-welded together,
a porous metal joint in which, at the joint, the microprojections of one of the porous metal members are inserted into the microdepressions of the other of the porous metal members, and the microprojections and the microdepressions are plastically deformed in a direction intersecting the overlapping direction,
The joint is characterized in that one of the overlapping surfaces constituting the overlapping portion of the two porous metal members has a convex portion including a large number of the micro-concavities and the micro-convex portions, and the other of the overlapping surfaces has a concave portion including a large number of the micro-concavities and the micro-convex portions and fitting into the convex portion . The joint is a part of the two porous metal members,
4. The porous metal joint according to claim 1 , wherein the joint portion and the portion adjacent to the joint portion have substantially the same thickness in the overlapping direction . A porous metal joint according to any one of claims 1, 3 and 4, characterized in that the two porous metal members are each a plate-shaped member, and the joint is a portion where the opposing end sides of the two porous metal members are overlapped and pressure-welded . 6. The porous metal joint according to claim 1, wherein the two porous metal members are both made of a porous metal material having continuous pores, thereby forming a filter . 7. The porous metal joint according to claim 1, wherein the joint portion is compressed and deformed to have a thickness that is 20 to 40% of the thickness before pressure welding. The method for manufacturing a porous metal joint according to any one of claims 1 to 7, characterized in that it includes a step of overlapping one of the porous metal members with the other of the porous metal members, and a step of pressing both of these porous metal members from both sides in the overlapping direction to form the joint. 9. The method for producing a porous metal joint according to claim 8, wherein the porous metal member is formed by subjecting a porous substrate to an electrically conductive treatment, then subjecting the porous substrate to electroplating, and then removing the porous substrate.

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