Porous metal joint and method for producing same

Abstract

To obtain a sufficient bond strength.SOLUTION: A porous metal joint has a junction 10 in which at least parts of two porous metal components 1, 2, which have many minute recesses a1 and minute protrusions a2 on surfaces, are overlapped and pressure-welded. At the junction 10, in the state that the minute protrusion a2 of one porous metal component 1 enters in the minute recess a1 of the other porous metal component 2, the minute protrusion a2 and the minute recess a1 are plastically deformed in a cross direction to the overlapping direction.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a porous metal joined body formed by joining porous metal members together, and a method for producing the same. [Background technology]

[0002] Conventional inventions of this type include, for example, a method for joining filter materials, as described in Patent Document 1. In this joining method, two metal foam filter substrates having a large number of communicating pores are compressed and densified at their ends, and then the densified ends are overlapped and the overlapped portion is welded. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP2005-144380A Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned conventional technology is intended to ensure joint strength by welding the densified portions, but this requires a large number of work steps and there is a demand for improvements in productivity. [Means for solving the problem]

[0005] In view of the above problems, the present invention has the following configuration. 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. At the same time, in the overlapping direction The porous metal member has a press-welded joint, and in the joint, when the minute projections of one of the porous metal members are inserted into the minute recesses of the other of the porous metal members, the minute projections and the minute recesses are aligned in a direction perpendicular to the overlapping direction. and each in a random direction 2. A porous metal joint, characterized in that the porous metal joint is plastically deformed. Effect of the Invention

[0006] Since the present invention is configured as described above, sufficient joint strength can be obtained without any welded parts, and productivity is also good. [Brief description of the drawings]

[0007] [Figure 1] 1 is a perspective view showing an example of a porous metal joint according to the present invention. [Diagram 2] FIG. 2 is a cross-sectional view taken along line (II)-(II) in FIG. [Diagram 3] 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, 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. [Figure 4] 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 one shown in the figure has been dyed with a dye. [Diagram 5] 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. [Figure 6] 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. [Figure 7] 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. [Figure 8] 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). [Figure 9]5A and 5B are perspective views showing the steps of producing the porous metal joint, in which (a) shows a porous metal member in which notches are formed, and (b) shows the porous metal member in a state where a bending process has been performed between adjacent notches. [Figure 10] 1A and 1B are oblique views 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. [Figure 11] 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). [Figure 12] 11(b) are cross-sectional views showing the manufacturing procedure of the porous metal joint at the same cross-sectional position as in 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. [Figure 13] 1 is a diagram and a table showing the results of a comparative experiment on a porous metal joint according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] 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-depressions and micro-protrusions on their surfaces overlapped and pressed together, and at the joint, the micro-protrusions of one of the porous metal members are inserted into the micro-depressions of the other of the porous metal members, and these micro-protrusions and micro-recesses are plastically deformed in a direction intersecting the overlapping direction (see Figures 1 to 13).

[0009] A second feature is that in the joint, the numerous minute protrusions and minute recesses are plastically deformed in random directions that intersect the overlapping direction (see Figs. 5 and 6).

[0010] A third feature is that the joint is a part of the two porous metal members, and the joint and a part adjacent to the joint have substantially the same thickness in the overlapping direction (see FIG. 7).

[0011] The fourth feature is that the two porous metal members are each plate-shaped members, and the joint is a portion where opposing end sides of the two porous metal members are overlapped and pressed together (see Figures 1 to 3, 7 to 8, and 11 to 12).

[0012] A fifth feature is that a plurality of notches are provided at one end side of each of the porous metal members at intervals in the extension direction of the one end, and adjacent notches form a pressure-welded piece portion, and 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 overlapped and pressure-welded in the extension direction (see Figures 8 to 10).

[0013] As a sixth feature, the joint has a convex portion including a large number of the minute recesses and minute protrusions on one of the overlapping surfaces constituting the overlapping portion of the two porous metal members, and has a concave portion including a large number of the minute recesses and minute protrusions and fitting into the convex portion on the other overlapping surface (see Figures 11 and 12).

[0014] As a seventh feature, the two porous metal members are both made of a porous metal material having continuous pores, thereby forming a filter.

[0015] An eighth feature 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 (see Figures 3 and 12).

[0016] As a ninth feature, the porous metal member is obtained by subjecting a porous base material to a conductive treatment, then subjecting it to electroplating, and then removing the porous base material.

[0017] <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.

[0018] The porous metal joint A shown in Figure 1 is formed by overlapping and pressing at least a portion (in the illustrated example, the opposing ends) of two porous metal members 1 and 2 having a large number of micro-depressions a1 and micro-protrusions a2 on their surfaces to form a joint 10.

[0019] Each of the porous metal members 1, 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.

[0020] It should be noted that 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 having approximately the same external shape, depending on the pressing strength, the mesh structure is destroyed and the base material crumbles like ashes, and it is not possible to obtain a joint strength similar to that of the porous metal joint A.

[0021] There are various processing requirements for the application products of the porous metal bonded body A, such as a large-area filter in which multiple base materials are connected together. Therefore, a technology is desired for the porous metal bonded body A that can be easily processed with minimal destruction of the three-dimensional mesh structure and without increasing the number of work steps. 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.

[0022] On the front and back surfaces of each of the porous metal members 1 and 2, a large number of minute recesses a1 and minute protrusions a2, which are formed from parts of the pores a and parts of the walls surrounding the pores a, are exposed.

[0023] Each of the porous metal members 1 and 2 having the above-mentioned configuration is formed into a predetermined shape (in the illustrated example, a rectangular flat plate shape).

[0024] The procedure for joining the two porous metal members 1 and 2 will be explained 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 between the upper mold M2 and the lower mold M1 on both sides in the overlapping direction (top and bottom in the illustrated example), 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.

[0025] 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 surface plate having a flat upper surface can be used as the lower mold M1.

[0026] The upper die M2 is made of a hard metal material, and has a lower end surface formed in a rectangular flat surface shape for pressing the joint portion 10 from above. The upper die M2 is generally formed in, for example, a rectangular parallelepiped shape.

[0027] In the upper die M2, the vertical dimension of the lower end portion M2a is set to a length including the dimension W1 of the porous metal members 1, 2 in the width direction (see FIG. 1). The lateral dimension of the lower end portion M2a is set to a length including the overlapping portion W2 at the joint 10 (see FIG. 3(b)).

[0028] In the joint 10, the metal portions constituting the pores a, minute recesses a1, minute protrusions a2, etc. are compressed and deformed in various directions (see FIG. 5).

[0029] 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, we can see that the micro-convex portion a2 of one porous metal member 1 (or 2) enters or fits into the micro-concave portion a1 of the other porous metal member 2 (or 1), and these micro-convex portion a2 and micro-concave portion a1 are plastically deformed in a direction that is perpendicular to the overlapping direction and that is also random.

[0030] 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 of FIG. 2, it is the up-down direction.

[0031] 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 this arrangement direction and depth direction.

[0032] Moreover, the term "random direction" means that the direction in which the numerous minute protrusions a2 and minute recesses a1 are plastically deformed 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.

[0033] The plastic deformation may occur in such a manner that the minute protrusions a2 or minute recesses a1 deform in only one of the intersecting directions, or may deform so as to expand or contract in both the intersecting directions.

[0034] 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 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.

[0035] The relationship between the minute protrusion a2 and the minute recess a1 that fits into this minute 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.

[0036] 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 at the joint 10. In one example of this embodiment, the thickness t is set to about ⅓ of the thickness T.

[0037] 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 continuous internal 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 have air permeability. 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.

[0038] <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, and therefore the modified parts will be mainly described in detail.

[0039] A porous metal joint B shown in FIG. 7 is configured such that the joint 10 and the portion adjacent to the joint 10 of the porous metal joint A have approximately the same thickness in the overlapping direction.

[0040] In more detail, this porous metal joint B is sandwiched and pressed from both sides in the overlapping direction between 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 equal to each other.

[0041] 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 bonded portion 10 and the adjacent portion, stress concentration due to differences in level, corners, etc. does not occur, and the porous metal bonded body B has an excellent appearance.

[0042] As another manufacturing method, the joint portion 10 and the portion adjacent to the joint portion 10 can be compressed separately to manufacture a porous metal joint B having almost no steps.

[0043] <Third embodiment> A porous metal joint C shown in FIGS. 8(a) and 8(b) is obtained by replacing the joint 10 in the porous metal joint A with a joint 20. As shown in FIG.

[0044] The manufacturing procedure for this porous metal joint C will be described below. First, a plurality of cuts 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 multiple rectangular, flat pressure-welded pieces 1b (2b).

[0045] 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 caused by the upper die M2 is formed on the upper surfaces of the two porous metal members 1 and 2 (see FIG. 8(b)).

[0046] In the joint 20 formed in the manner described above, between the overlapping pressure-welded pieces 1b, 2b, the minute convex portion a2 of one porous metal member 1 (or 2) fits into the minute concave portion a1 of the other porous metal member 2 (or 1), and these minute convex portion a2 and minute concave portion a1 are plastically deformed in directions that are perpendicular to the overlapping direction and that are random.

[0047] 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 a curved surface at the joints, the joint strength can be kept relatively high due to the interlocking structure described above.

[0048] <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 with an upper mold M3 (see Figure 3) in the manufacturing method of the porous metal bonded body A.

[0049] The manufacturing procedure of the porous metal bonded body D will be described in detail. 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 with each other (see FIG. 12(a)). This step is the same as the manufacturing procedure of the porous metal bonded body A described above.

[0050] 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 impression marks 30a are formed on the upper surfaces of the two porous metal members 1 and 2 by the plurality of upper dies M3.

[0051] Each upper die M3 is formed in a generally cylindrical shape extending in the vertical direction, and the periphery 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 one example in Figure 11), and multiple upper molds M3 are also provided in the width direction of the porous metal members 1, 2 (five in one example in Figure 11). These upper dies M3 are connected at their upper ends and move up and down as a unit.

[0052] 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)). Moreover, 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 protrusions 31, respectively.

[0053] At the joint 30, between the convex portion 31 and the concave portion 32 which are fitted together vertically, the minute convex portion a2 of one porous metal member 1 (or 2) fits into the minute concave portion a1 of the other porous metal member 2 (or 1), and these minute convex portion a2 and minute concave portion a1 are plastically deformed in a direction that is perpendicular to the overlapping direction and that is also random.

[0054] Therefore, according to the porous metal joint D illustrated in Figures 11(a) and (b), substantially the same effect as the porous metal joint A can be obtained, and in addition, the fitting and pressure contact between the convex portion 31 and the concave portion 32 restricts the horizontal movement of the porous metal members 1 and 2, thereby further improving the joint strength between the two porous metal members 1 and 2.

[0055] <Results of the comparative experiment> Next, the results of a tensile strength test performed on the porous metal joint having the above 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.

[0056] In this experiment, for each of Examples 1 to 4 and Comparative Example, 10 test pieces 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 the overlapping portions of the porous metal members 1 and 2 were compressed to form the joint 10 was 5 MP.

[0057] 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.

[0058] Example 4 has the basic structures of both the porous metal bonded body C and the porous metal bonded body D. That is, Example 4 is obtained by forming a plurality of convex portions 31 and concave portions 32 (see FIG. 11) on the porous metal bonded body C (see FIG. 8) having a plurality of pressure-welded piece portions 1b, 2b.

[0059] In the comparative example, the opposing overlapping portions of the porous metal member 1 and the porous metal member 2 were pressed and compressed with a flat die, and then spot-welded at two locations. The spot welding conditions were 9 cycles of current application, a current of 7000 A, and a pressure of 0.25 MPa.

[0060] 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.

[0061] From 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 steel can be obtained.

[0062] <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.

[0063] Furthermore, according to the above embodiment, the thickness is approximately the same between one porous metal member 1 and the other porous metal member 2, but as another example, it is also possible to make the thickness different between one porous metal member and the other porous metal portion.

[0064] Furthermore, 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.

[0065] In the above embodiment, the shape of the pressure-welded portion can be other than the flat surface or circle described above. That is, 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, or the like, by changing the shape of the upper die.

[0066] In addition, in the above embodiment, sufficient joint strength is obtained by only the above-mentioned pressure welding of the overlapping parts of the porous metal member 1 and the porous metal member 2 without welding them, but as another example, it is also possible to weld the overlapping parts in addition to pressing them as described above.

[0067] Furthermore, the present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the gist of the present invention. [Explanation of symbols]

[0068] 1, 2: Porous metal material 1a, 2a: Cutting 1b, 2b: Pressure welding piece 10,20,30:Joint part 31: Convex part 32: Concave part A~D: Porous metal joint M1: Lower mold M2,M3: Upper mold a: Pore a1: Micro recess a2: Small convex part

Claims

1. 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.

2. A joint in which at least a portion of two porous metal members having a large number of minute recesses and minute protrusions on the surface are overlapped and pressure-welded, 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 one end of each of the porous metal members at intervals in the extension direction of the one end, 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 overlapped and pressure-welded in the extension direction.

3. A joint in which at least a portion of two porous metal members having a large number of minute recesses and minute protrusions on the surface are overlapped and pressure-welded, 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.

4. 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.

5. A porous metal joint as described in any one of claims 1, 3 or 4, characterized in that the two porous metal members are each plate-shaped members, and the joint is a portion where the opposing end sides of the two porous metal members are overlapped and pressed together.

6. A porous metal joint as described in any one of claims 1 to 5, characterized in that the two porous metal members are both formed from a porous metal material having continuous pores, thereby forming a filter.

7. A porous metal joint as described in any one of claims 1 to 6, characterized in that the joint is compressed and deformed so that the thickness is 20 to 40% of the thickness before being pressed.

8. The method for producing a porous metal joint according to any one of claims 1 to 7, further comprising the steps of: overlapping one of the porous metal members with the other of the porous metal members; and pressing both of the porous metal members from both sides in a direction in which the members are overlapped to form the joint.

9. 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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