Recycling method of member and manufacturing method of recycling joint member

Abstract

To provide a recycling method of a member that enables a member obtained by decomposition of a joint member to be recycled without melting the member.SOLUTION: Provided is a recycling method of a member including steps of: preparing a joint member having a junction containing a foaming agent and having a plurality of members joined via the junction by friction stir welding; heating the foaming agent to cause foaming of the junction; and breaking the junction after foaming to decompose the joint member and obtaining a member having at least a part of the junction after foaming. In the method, the obtained member is recycled as a member forming a recycle joint member.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for recycling components and a method for producing recycled joined components. [Background technology]

[0002] As the use of multi-material components is promoted, friction stir welding (FSW) has been attracting attention as one of the joining techniques for dissimilar components. Friction stir welding is capable of solid-state joining and can achieve strong joints, so its use in various fields is being considered.

[0003] For example, from the viewpoint of improving fuel efficiency of automobiles, the joining of steel members and aluminum members has been considered. However, if the steel members and aluminum members are joined by friction stir welding, it is possible to minimize the formation of a brittle Fe-Al intermetallic compound layer and achieve a strong bond.

[0004] On the other hand, from the perspective of realizing a recycling-oriented society, it is necessary for joining materials to be easy to dismantle when they are disposed of. Therefore, if a technology could be established that would firmly join the materials together when they are in use, and allow them to be easily dismantled when they are disposed of (easy separation technology), it would be easier to recycle the materials and significantly reduce energy consumption throughout their life cycle.

[0005] According to the research of the inventors of the present invention, when joining components (for example, joining a steel component and an aluminum component), a foaming agent such as TiH2 is added to the joining surface of the components, and then friction stir welding is performed to disperse the foaming agent in the aluminum component, which enables strong joining of the components, and when it is time to discard the joined components, the joint between the components is heated to decompose the foaming agent and foam the joint, making it possible to separate the components with a low load (for example, see Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] "Study on easy separation by applying foaming agent to the joint interface of A1050 aluminum / SS400 steel joint to make it porous," Light Metals, Vol. 73, No. 4, pp. 164-166, 2023 Summary of the Invention [Problem to be solved by the invention]

[0007] The bonded components, which are bonded by dispersing a foaming agent in the components, are then dismantled by foaming the foaming agent, and each component obtained by dismantling is melted and recycled. However, from the perspective of realizing a recycling-oriented society, there is a demand for reducing the energy required to melt the components and reusing the dismantled components.

[0008] Therefore, one aspect of the present invention aims to provide a method for recycling components, which allows components obtained by dismantling a bonded member to be reused without melting the components. Another aspect of the present invention aims to provide a method for producing a recycled bonded member that can be dismantled with a low load by reusing the components obtained by dismantling a bonded member. [Means for solving the problem]

[0009] The present invention includes, for example, the following [1] to [8]. [1] A step of preparing a joint member having a joint portion containing a foaming agent and in which a plurality of members are joined via the joint portion by friction stir welding; Heating the foaming agent to foam the joint; and a step of dismantling the joint member by breaking the joint portion after foaming to obtain a member having at least a part of the joint portion after foaming, The resulting member is reused as a member constituting a recycled joint member. [2] A method for producing a joining member including a first member having a region containing a foaming agent and a second member, comprising the steps of: a joining step of joining the first member and the second member by friction stir welding in a manner including the region. [3] The manufacturing method described in [2], further comprising a recovery step of dismantling a joined member including the first member before the joining step to obtain the first member. [4] The manufacturing method described in [3], further comprising a molding step of molding the first component obtained in the recovery step prior to the joining step. [5] The method according to any one of [2] to [4], wherein the foaming agent contains titanium hydride. [6] The manufacturing method described in any one of [2] to [5], wherein the region further contains a thickener. [7] The method according to [6], wherein the thickener comprises alumina. [8] The joining step includes a step of disposing a foaming agent sheet between the first member and the second member; and joining the first member and the second member by friction stir welding so as to include the region and the foaming agent sheet, The method according to any one of [2] to [7], wherein the foaming agent sheet contains a metal and a foaming agent. Effect of the Invention

[0010] According to one aspect of the present invention, there is provided a method for recycling components, which allows components obtained by dismantling a bonded member to be reused without melting the components. According to another aspect of the present invention, there is provided a method for producing a recycled bonded member, which allows components obtained by dismantling a bonded member to be reused and can be dismantled under low load. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic cross-sectional view illustrating a method for recycling a member. [Diagram 2] FIG. 2 is a schematic diagram illustrating a method for producing a recycled bonded member. [Diagram 3] FIG. 3 is a schematic diagram illustrating a method for producing a bonding member using the foaming agent sheet produced in Example 1. [Figure 4] FIG. 4 is a photograph of the bonded member produced in Example 1. [Diagram 5] FIG. 5 is a photograph of the joint of the joint member produced in Example 1 after foaming. [Figure 6] FIG. 6 is a photograph of the joint member produced in Example 1 after being disassembled. [Figure 7] FIG. 7 is a photograph of the recycled bonded member produced in Example 1. [Figure 8] FIG. 8 is a photograph of the joint of the recycled joint member produced in Example 1 after foaming. [Figure 9] FIG. 9 is a photograph of the recycled joint member produced in Example 1 after being disassembled. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, the same or corresponding parts are designated by the same reference numerals, and duplicated description will be omitted.

[0013] <How to recycle materials> A method for recycling components according to one embodiment of the present invention includes the steps of: preparing a joined component having a joint containing a foaming agent and in which a plurality of components are joined via the joint by friction stir welding (step (a)); foaming the joint by heating the foaming agent (step (b)); and dismantling the joined component by breaking the foamed joint to obtain a component having at least a part of the foamed joint (step (c)). The obtained components are reused as components that constitute a recycled joined component.

[0014] A joint member (hereinafter, simply referred to as a "joint member") having a joint containing a foaming agent and having a plurality of members joined via the joint by friction stir welding can be dismantled at a low load by foaming the joint and then breaking the foamed joint, and a member can be obtained from the joint member. The inventors have conducted research and confirmed by X-ray diffraction (XRD) that when a member (recycled member) obtained by dismantling the joint member has at least a part of the foamed joint, the foamed joint contains undecomposed foaming agent. Then, a joint member can be manufactured by friction stir welding a recycled member and another member so as to include the foamed joint. Furthermore, it was found that when the joint of the manufactured joint member is heated, the undecomposed foaming agent is decomposed, causing the joint to foam, and the joint member can be dismantled at a low load. Therefore, according to the member recycling method according to one embodiment of the present invention, the member obtained by dismantling the joint member can be reused without melting. In addition, a recycled joint member that can be dismantled at a low load can be manufactured by reusing the member obtained by dismantling the joint member.

[0015] Fig. 1 is a schematic cross-sectional view illustrating a method for recycling a member. As shown in Fig. 1(a), in step (a), a joined member 10 is prepared, which has a joint 5 containing a foaming agent and in which a plurality of members (members A and B in Fig. 1(a)) are joined via the joint 5 by friction stir welding. The joined member 10 may be one that is scheduled to be discarded due to damage to members A and B that constitute the joined member 10, or the like.

[0016] Examples of the material of each of the multiple members constituting the joining member include aluminum, copper, iron, magnesium, titanium, nickel, zinc, and resin. These metals may be alloys. Examples of aluminum alloys include A6061, an Al-Mg-Si alloy, and ADC12, an Al-Si-Cu alloy. The material of each member is preferably a material containing aluminum, such as aluminum or an aluminum alloy, from the viewpoint of having a relatively low melting point and being able to easily perform friction stir welding.

[0017] The materials of the members in the plurality of members may be the same or different from each other. From the viewpoint of facilitating separation of the joining members, it is preferable that the materials of the members in the plurality of members are different from each other.

[0018] The shape of each of the multiple members is not particularly limited. When each of the members is in a plate shape, they can be easily joined by friction stir welding.

[0019] Examples of foaming agents contained in the joint of the joining members include titanium hydride (TiH2), calcium carbonate, zirconium hydride, magnesium carbonate, strontium carbonate, barium carbonate, chromium nitride, magnesium hydride, sodium hydrogen carbonate, ammonium carbonate, sodium bicarbonate, ammonium bicarbonate, ammonium nitrite, sodium borohydride, etc. When the members contain aluminum, the foaming agent is preferably titanium hydride from the viewpoint of stable foaming with aluminum. The joining member may contain multiple foaming agents.

[0020] The bonding part may further contain components other than the foaming agent (hereinafter, also referred to as "other components"), such as a thickener, a dispersant, a surface protective agent, and the like.

[0021] Examples of the thickener include alumina, magnesium oxide, silicon carbide, silicon dioxide, etc. When the joint contains a thickener, pores generated by foaming of the foaming agent are less likely to collapse during foaming, and the joint members can be easily disassembled.

[0022] 1(b), in step (b), the foaming agent is heated to foam the joint 5. Examples of heat source 6 for heating the joint 5 include a light source that irradiates infrared rays (e.g., a halogen lamp) and a heater.

[0023] When the joint 5 is heated, the foaming agent contained in the joint 5 decomposes and foams, forming a foam 7 in at least a part of the joint 5. The foam 7 contains pores 8 generated by the decomposition of the foaming agent. If the joint 5 contains a thickener, the pores 8 are less likely to collapse during foaming, making it easier to dismantle the joint member 10. Heating of the joint 5 (foaming agent) may be terminated when the foam 7 has expanded sufficiently, or may be terminated when a certain amount of time has elapsed since the start of heating.

[0024] As shown in FIG. 1(c), in step (c), the joint member 10 is disassembled by breaking the joint (foam 7) after foaming to obtain members A and B. In FIG. 1(c), each of the members A and B has a part of the joint (foam 7) after foaming, but it is preferable that one of the members A and B does not have the joint (foam 7) after foaming. The joint (foam 7) after foaming is broken, for example, by applying a load to the joint member 10 after foaming. The joint (foam 7) after foaming may break at the interface between the member A and the joint 5 (foam 7), or at the interface between the member B and the joint 5 (foam 7), or may break the joint 5 (foam 7). The joint (foam 7) after foaming preferably breaks at the interface between the member A and the joint 5 (foam 7), or at the interface between the member B and the joint 5 (foam 7).

[0025] The member (recycled member) obtained in step (c) has at least a part of the joint after foaming. Since the joint after foaming has a distorted shape, the recycled member may be molded before reuse, for example, by compressing the joint after foaming to flatten the surface of the member. In other words, the method for recycling a member may further include a step of molding the member obtained in step (c) after step (c).

[0026] The joint after foaming contains undecomposed foaming agent. Therefore, a joint member can be manufactured by friction stir welding a recycled member and another member so that the joint after foaming is included. When the joint of the manufactured joint member is heated, the undecomposed foaming agent is decomposed, and the joint foams. Therefore, even in the case of a joint member manufactured using recycled members, the members can be separated with a low load.

[0027] <Method of manufacturing recycled joint parts> As described above, a joint member can be manufactured using recycled members. The recycled member has at least a part of the joint portion after foaming, and since the joint portion after foaming contains undecomposed foaming agent, it can be said that the recycled member has a region containing a foaming agent (hereinafter, simply referred to as "region"). In this case, another embodiment of the present invention is a method for manufacturing a joint member including a member (first member) having a region containing a foaming agent and a member (second member) other than the first member, which includes a joining step of joining the first member and the second member by friction stir welding so as to include the region of the first member. The recycled joint member manufactured by reusing the member (first member) obtained by dismantling the joint member can be dismantled with a low load.

[0028] Examples of the material of the first member include aluminum, copper, iron, magnesium, titanium, nickel, zinc, and resin. When the first member includes a metal, the metal may be an alloy. For example, when aluminum includes an aluminum alloy, examples of the aluminum alloy include A6061, an Al-Mg-Si alloy, and ADC12, an Al-Si-Cu alloy. The material of the first member is preferably a material containing aluminum, such as aluminum or an aluminum alloy, from the viewpoint of having a relatively low melting point and being able to easily perform friction stir welding.

[0029] The material of the second member may be the same as that of the first member. The material of the second member may be the same as or different from that of the first member. From the viewpoint of facilitating separation of the recycled bonded members, the material of the second member is preferably different from that of the first member. The second member may be a member (recycled member) obtained by dismantling the bonded members, or may be an unused member (a member other than the recycled member).

[0030] The shapes of the first member and the second member are not particularly limited, but when the first member and the second member are each in a plate shape, they can be easily joined by friction stir welding.

[0031] The first member may be a member obtained by dismantling a bonding member (for example, member A in FIG. 1). That is, the first member may be a member having a region containing a foaming agent and obtained by dismantling a bonding member including at least the first member, and the manufacturing method for a recycled bonding member may further include a recovery step of dismantling the bonding member including the first member to obtain the first member before the bonding step.

[0032] Since the first component obtained in the recovery step corresponds to the recycled component in the above-mentioned component recycling method, the recovery step can be appropriately applied with the items described in the above-mentioned component recycling method. For example, the recovery step may include steps (a) to (c) in the component recycling method, and may further include a molding step of molding the first component obtained in the recovery step.

[0033] Examples of the foaming agent contained in the region include titanium hydride (TiH2), calcium carbonate, zirconium hydride, magnesium carbonate, strontium carbonate, barium carbonate, chromium nitride, magnesium hydride, sodium hydrogen carbonate, ammonium carbonate, sodium bicarbonate, ammonium bicarbonate, ammonium nitrite, sodium borohydride, etc. When the member contains aluminum, the foaming agent is preferably titanium hydride from the viewpoint of stable foaming with aluminum. The region may contain multiple foaming agents.

[0034] The region may further contain components other than the foaming agent (hereinafter also referred to as "other components"), such as a thickener, a dispersant, a surface protective agent, and the like.

[0035] Examples of the thickener contained in the region include alumina, magnesium oxide, silicon carbide, silicon dioxide, etc. When the region contains a thickener, pores generated by foaming of the foaming agent are less likely to collapse during foaming, making it easier to disassemble the recycled bonded members.

[0036] In the joining step, the first member and the second member are joined by friction stir welding so as to include the region. Fig. 2 shows a schematic diagram for explaining a method for producing a recycled joined member.

[0037] 2(a), first, a first member 21 and a second member 22 are arranged. At this time, in order to perform friction stir welding so as to include a region 23 containing a foaming agent, the first member 21 and the second member 22 are arranged so that at least a part of the region 23 of the first member 21 is joined to the second member 22. That is, the joining process may include a step of arranging the first member and the second member so that at least a part of the region of the first member is joined to the second member.

[0038] 2(b), the first member 21 and the second member 22 are joined by performing friction stir welding at the interface between the first member 21 and the second member 22. By performing friction stir welding, a joint 25 is formed at the interface between the first member 21 and the second member 22, and the foaming agent present in the region 23 is dispersed in the joint 25.

[0039] 2(b), friction stir welding is performed by rotating an FSW tool 24 and scanning the tool 24 along the interface between the first member 21 and the second member 22. The rotation speed and scanning speed of the tool 24 are adjusted according to the materials of the first member 21 and the second member 22, etc. From the viewpoint of uniformly dispersing the foaming agent in the joint 25, the tool 24 may be scanned multiple times.

[0040] In the joining step, a foaming agent may be supplied to the joining surface between the first member and the second member from the viewpoint of facilitating dismantling of the recycled joined member by providing a sufficient amount of foaming agent between the first member and the second member. Also, a component other than the foaming agent (e.g., the above-mentioned other components) may be supplied to the joining surface.

[0041] The method of supplying the foaming agent is not particularly limited, and examples thereof include (1) a method of attaching a double-sided tape to the joining surface and spraying the foaming agent on the double-sided tape, (2) a method of wrapping a powder of the foaming agent in a packaging material such as aluminum foil and sandwiching it between the joining surface, (3) a method of applying the foaming agent to the joining surface by spraying, (4) a method of preparing a slurry containing the foaming agent and applying the slurry to the joining surface by a brush or the like, and (5) a method of preparing a foaming agent sheet containing the foaming agent and disposing the foaming agent sheet between the first member and the second member. From the viewpoint of being able to uniformly supply a sufficient amount of foaming agent to the joining surface, a foaming agent sheet containing the foaming agent may be prepared and disposed between the first member and the second member. That is, the joining process may include a step of disposing a foaming agent sheet containing a metal and a foaming agent between the first member and the second member, and a step of joining the first member and the second member by friction stir welding so as to include the region and the foaming agent sheet.

[0042] Examples of metals contained in the foaming agent sheet include aluminum, copper, iron, magnesium, titanium, nickel, and zinc. These metals may be alloys. From the viewpoint of not changing the properties of the members, the metal contained in the foaming agent sheet is preferably the same as the metal contained in the first member and / or the second member. The foaming agent sheet may contain a plurality of metals.

[0043] The foaming agent sheet may contain components other than the metal and foaming agent, for example, a thickener (such as alumina).

[0044] The foaming agent sheet may have a thickness of 5 mm or less, 3 mm or less, or 2 mm or less. The foaming agent sheet may have a thickness of 0.5 mm or more.

[0045] The foaming agent sheet can be produced, for example, by sintering a metal powder and a powdered foaming agent by Spark Plasma Sintering (SPS). The foaming agent sheet can also be produced, for example, by adding a foaming agent to a molten metal, mixing them, and then molding the resulting mixture.

[0046] The recycled joint member can be dismantled in the same manner as the joint member described above. That is, the joint between the first member and the second member is heated by a heat source, and the foaming agent contained in the joint is decomposed to form a foam at least in a part of the joint, and a load is applied to the joint member to break the foam and separate the first member and the second member. When the joint of the recycled joint member is foamed to form a foam, the load and energy required for separation can be reduced compared to when the joint of the joint member is separated without foaming. EXAMPLES

[0047] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to the following examples.

[0048] Example 1 [Preparation of foaming agent sheet] Aluminum powder (average particle size 20μm) was prepared as the metal powder, titanium hydride powder (TiH2, average particle size 45μm or less) was prepared as the foaming agent powder, and alumina powder (Al2O3, average particle size 1μm) was prepared as the thickener (pore shape stabilizer) powder. The amounts of each were 5 mass% for aluminum powder, 1 mass% for titanium hydride powder, and 3 mass% for alumina powder relative to the mass per unit volume of the joint (area stirred by FSW) of the joint members.

[0049] Next, the prepared powders were mixed and solidified by spark plasma sintering (SPS). SPS was performed using SPS-1050 (manufactured by Sumitomo Coal Mining Co., Ltd.) at 520°C and 50 MPa for 5 minutes. A disk-shaped foaming agent sheet with a diameter of 20 mm and a thickness of 0.8 mm was produced by SPS. The foaming agent sheet produced was brittle and broke when bent strongly, but did not collapse without applying force and was able to maintain its shape.

[0050] [Production of joining members] Figure 3 shows a schematic diagram of the method for producing the joint members. First, as shown in Figure 3(a), a foaming agent sheet was placed between a rolled steel SS400 plate material and a rolled industrial pure aluminum A1050 plate material, and friction stir welding was performed in air. The friction stir welding was performed by scanning an FSW tool (steel, shoulder diameter 17 mm, probe length 4.8 mm, probe diameter 5 mm, with screw) along the joint interface. The tool rotation speed during friction stir welding was 2200 rpm, the tool scanning speed was 100 mm / min, and the forward angle was 3°. As shown in Figure 3(b), the friction stir welding was performed by scanning the tool so that the side of the probe was inserted 0.8 mm into the steel SS400 plate material side from the joint interface. A planar photograph of the produced recycled joint member is shown in Figure 4(a), and a side photograph is shown in Figure 4(b).

[0051] [Separation of jointed parts] The joints of the prepared joint members were heated by light irradiation from a halogen lamp, and the foaming agent was decomposed to form a foam at the joint. At this time, the distance between the halogen lamp and the joint members was 40 mm, and the output of the halogen lamp was 1620 W. Heating with the halogen lamp was stopped when the joints had sufficiently expanded. A plan view of the joint members after foaming is shown in Figure 5(a), and a side view of Figure 5(b), respectively. Next, the joint members, a rolled steel SS400 plate material and a rolled industrial pure aluminum A1050 plate material, were each held, and bending stress was applied to the joints of the joint members. The joint members could be easily separated with a low load. A plan view of the joint members after separation is shown in Figure 6(a), and a side view of Figure 6(b), respectively.

[0052] [Production of recycled joint materials] The foamed areas of the industrially pure aluminum A1050 rolled plate obtained by separating the joined members were compressed to obtain recycled industrially pure aluminum A1050 rolled plate. Next, in the same manner as in [Preparation of Joined Members] above, the steel SS400 rolled plate and the recycled industrially pure aluminum A1050 rolled plate were joined by friction stir welding to obtain a recycled joined member. At this time, the friction stir welding was performed so as to include the compressed areas of the foamed areas of the industrially pure aluminum A1050 rolled plate. A plan view photograph of the produced recycled joined member is shown in FIG. 7(a), and a side view photograph is shown in FIG. 7(b).

[0053] [Separation of recycled joint parts] The joints of the produced recycled joint members were heated by light irradiation from a halogen lamp in the same manner as in [Separation of joint members] above, and foam was formed in the joints. A plan view of the recycled joint members after foaming is shown in Fig. 8(a), and a side view of the recycled joint members after foaming is shown in Fig. 8(b). Next, the rolled steel SS400 plate material of the recycled joint members and the rolled recycled industrial pure aluminum A1050 plate material were each held, and bending stress was applied to the joints of the recycled joint members. The recycled joint members could be easily separated with a lower load than when the joints were not foamed. A plan view of the recycled joint members after separation is shown in Fig. 9(a), and a side view of the recycled joint members after separation is shown in Fig. 9(b). [Explanation of symbols]

[0054] A, B...members, 6...heat source, 7...foam, 8...air hole, 10, 20...jointing member, 21...first member, 22...second member, 23...area, 24, 34...tool, 5, 25...joint, 31...industrially pure aluminum A1050 rolled plate material, 32...steel SS400 rolled plate material, 36...foaming agent sheet.

Claims

1. A step of preparing a joint member having a joint portion containing a foaming agent and in which a plurality of members are joined via the joint portion by friction stir welding; Heating the foaming agent to foam the joint; and a step of dismantling the joint member by breaking the joint portion after foaming to obtain a member having at least a part of the joint portion after foaming, The resulting member is reused as a member constituting a recycled joint member.

2. A method for producing a joint member including a first member having a region containing a foaming agent and a second member, comprising the steps of: a joining step of joining the first member and the second member by friction stir welding in a manner including the region.

3. The manufacturing method according to claim 2 , further comprising a recovery step of dismantling a joined member including the first member to obtain the first member, prior to the joining step.

4. The manufacturing method according to claim 3 , further comprising a molding step of molding the first member obtained in the recovery step, prior to the joining step.

5. The method of claim 2 , wherein the blowing agent comprises titanium hydride.

6. The method of claim 2 , wherein the region further comprises a thickening agent.

7. The method of claim 6 , wherein the thickening agent comprises alumina.

8. the joining step includes the steps of: disposing a foaming agent sheet between the first member and the second member; and joining the first member and the second member by friction stir welding so as to include the region and the foaming agent sheet, The method according to claim 2 , wherein the foaming agent sheet contains a metal and a foaming agent.

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