Foaming agent sheet, method for manufacturing the same, and method for manufacturing porosity metal

Abstract

To provide a foaming agent sheet and a method for manufacturing the same, with which it is possible to evenly apply a sufficient amount of a foaming agent to a joint surface between members when joining the members together.SOLUTION: A foaming agent sheet contains metal and a foaming agent and is used for joining members together. A method for manufacturing a foaming agent sheet includes sintering metal powder and a powder-shaped foaming agent by discharge plasma sintering method. A method for manufacturing a foaming agent sheet includes: obtaining a mixture by mixing molten metal and a foaming agent; and forming the mixture in a sheet shape.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a foaming agent sheet and a method for producing the same, and a method for producing metal foam. [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] However, when adding a foaming agent directly to the joint surface between components, it is difficult to apply the foaming agent evenly to the joint surface, and there may be unevenness in the amount of foaming agent added depending on the position, making it difficult to add a sufficient amount of foaming agent.

[0008] Therefore, one aspect of the present invention aims to provide a foaming agent sheet that can add a sufficient amount of foaming agent evenly to the joining surface of components when joining the components, and a manufacturing method thereof. [Means for solving the problem]

[0009] The present invention includes, for example, the following [1] to [9]. [1] A method for producing a foam comprising the steps of: A foaming agent sheet used to bond components together. [2] The foaming agent sheet according to [1], wherein the metal includes aluminum. [3] The foaming agent sheet according to [1] or [2], wherein the foaming agent contains titanium hydride. [4] The foaming agent sheet according to any one of [1] to [3], further comprising a thickener. [5] The foaming agent sheet according to [4], wherein the thickener contains alumina. [6] The foaming agent sheet according to any one of [1] to [5], which has a thickness of 5 mm or less. [7] A method for manufacturing a foaming agent sheet, comprising the step of sintering a metal powder and a powdered foaming agent by spark plasma sintering. [8] A step of mixing the molten metal and a foaming agent to obtain a mixture; forming the mixture into a sheet; A method for producing a foaming agent sheet comprising the steps of: [9] A step of laminating a first metal member, a foaming agent sheet, and a second metal member in this order; A step of obtaining a precursor including at least a portion of the first metal member, at least a portion of the foaming agent sheet, and at least a portion of the second metal member by friction stir welding so as to include the foaming agent sheet; heating the precursor to obtain a metal foam; Equipped with The foaming agent sheet contains a metal and a foaming agent. Effect of the Invention

[0010] According to one aspect of the present invention, it is possible to provide a foaming agent sheet that can add a sufficient amount of foaming agent evenly to the joining surface of components when joining the components, and a manufacturing method thereof. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram illustrating a method for producing a joint member. [Diagram 2] FIG. 2 is a schematic cross-sectional view illustrating a method for separating the bonding members. [Diagram 3] FIG. 3 is a schematic diagram illustrating a method for producing the metal foam of Example 1. [Figure 4] FIG. 4 is a schematic diagram illustrating a method for producing the joint member of Example 2. As shown in FIG. [Diagram 5] FIG. 5 is a schematic diagram of the bonded member produced in Example 2. As shown in FIG. [Figure 6] FIG. 6 is a set of photographs showing the state of the bonding member after foaming before and after separation. [Figure 7] FIG. 7 shows the load-displacement curve obtained when a four-point bending test was performed on the bonded member after foaming. [Figure 8]FIG. 8 shows the load-displacement curve obtained when a four-point bending test was performed on an unfoamed joint member. 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] <Foaming agent sheet> A foaming agent sheet according to an embodiment of the present invention contains at least a metal and a foaming agent, and is used for joining members together. By disposing such a foaming agent sheet between the members and performing friction stir welding, a sufficient amount of foaming agent can be added evenly to the joining surfaces of the members.

[0014] 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 member, it is preferable that the metal contained in the foaming agent sheet is the same as the metal contained in the member to which the foaming agent sheet is applied. The foaming agent sheet may contain multiple metals.

[0015] Examples of the foaming agent 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 foaming agent sheet may contain multiple foaming agents.

[0016] The foaming agent sheet may further contain components other than the metal and the foaming agent (hereinafter also referred to as "other components"), such as a thickener, a dispersant, a surface protective agent, etc.

[0017] Examples of the thickener include alumina, magnesium oxide, silicon carbide, silicon dioxide, etc. When the foaming agent sheet contains a thickener, pores generated by foaming of the foaming agent are less likely to collapse during foaming, and the joining members can be easily dismantled.

[0018] 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.

[0019] <Method of manufacturing foaming agent sheet> The foaming agent sheet described above can be manufactured, for example, by sintering a metal powder, a powdered foaming agent, and, if necessary, powders of other components (for example, a powdered thickener) by a spark plasma sintering (SPS) method. That is, another embodiment of the present invention is a method for manufacturing a foaming agent sheet, comprising a step of sintering a metal powder and a powdered foaming agent by a spark plasma sintering method. SPS can be performed by a known method.

[0020] The foaming agent sheet described above can be manufactured, for example, by adding a foaming agent to a molten metal, mixing the two, and then molding the resulting mixture. That is, another embodiment of the present invention is a method for manufacturing a foaming agent sheet, comprising a step of mixing a molten metal and a foaming agent to obtain a mixture, and a step of molding the mixture into a sheet.

[0021] The method of mixing the molten metal and the foaming agent may be a known method. When the foaming agent sheet contains other components, the other components may be mixed with the molten metal together with the foaming agent, may be mixed with the molten metal before the addition of the foaming agent, or may be mixed with the molten metal after the addition of the foaming agent. When mixing each component with the molten metal, each component may be mixed while heating the molten metal from the viewpoint of preventing the temperature of the molten metal from decreasing.

[0022] After mixing the molten metal with each component, the resulting mixture is cooled and formed into a sheet. The method for forming the mixture into a sheet may be a known method.

[0023] <Method of manufacturing joining member> The joining member can be manufactured by disposing the above-mentioned foaming agent sheet between a first member and a second member, and performing friction stir welding at the interface between the first member and the second member on which the foaming agent sheet is disposed. That is, another embodiment of the present invention is a manufacturing method for a joining member, which includes a step of disposing a foaming agent sheet between a first member and a second member, and a step of performing friction stir welding at the interface between the first member and the second member on which the foaming agent sheet is disposed, and the foaming agent sheet contains a metal, a foaming agent, and other components (e.g., a thickener) as necessary. The joining member manufactured in this way can be added to the joining surface of the members evenly in a sufficient amount by disposing a foaming agent sheet at the joining portion between the members and performing friction stir welding.

[0024] 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.

[0025] 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 joining members, it is preferable that the material of the second member is different from that of the first member.

[0026] 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.

[0027] Fig. 1 is a schematic diagram illustrating a method for producing a joint member 10. First, as shown in Fig. 1(a), the foaming agent sheet 3 described above is placed between a first member 1 and a second member 2. Next, friction stir welding is performed at the interface between the first member 1 and the second member 2.

[0028] Friction stir welding is performed by rotating an FSW tool 4 and scanning the tool 4 along the interface between the first member 1 and the second member 2, as shown in Fig. 1(b). The rotation speed and scanning speed of the tool 4 are adjusted according to the materials of the first member 1 and the second member 2, etc. From the viewpoint of uniformly dispersing the foaming agent in the joint 5 between the first member 1 and the second member 2, the tool 4 may be scanned multiple times.

[0029] In this way, by arranging a foaming agent sheet at the interface between the first member 1 and the second member 2 and performing friction stir welding, the foaming agent can be easily dispersed in the joint between the first member 1 and the second member 2. This makes it possible to limit the range in which the foaming agent is foamed when the joint member 10 is discarded.

[0030] <Method of separating joint members> 2 is a schematic cross-sectional view illustrating a method for separating the joint member 10. First, as shown in Fig. 2(a), the joint portion 5 between the first member 1 and the second member 2 is heated by a heat source 6. Examples of the heat source 6 include a light source that irradiates infrared rays (e.g., a halogen lamp), a heater, etc.

[0031] When the joint 5 is heated, as shown in FIG. 2(b), the foaming agent contained in the joint 5 is decomposed to foam, and a foam 7 is formed in at least a part of the joint 5. The foam 7 contains pores 8 generated by the decomposition of the foaming agent. When the joint 5 contains a thickener, the pores 8 are less likely to collapse during foaming, and the joint member 10 becomes easier to dismantle. Heating of the joint 5 may be terminated when the foam 7 has expanded sufficiently, or may be terminated when a certain time has elapsed since the start of heating.

[0032] Next, by applying a load to the joining member 10, the foam 7 breaks, and the joining member 10 is separated into the first member 1 and the second member 2. The breakage of the foam 7 may occur at the interface between the first member 1 and the joining portion 5 (foam 7), may occur at the interface between the second member 2 and the joining portion 5 (foam 7), or may occur so as to divide the joining portion 5 (foam 7). The breakage of the foam 7 preferably occurs at the interface between the first member 1 and the joining portion 5 (foam 7), or at the interface between the second member 2 and the joining portion 5 (foam 7). When the joining portion 5 of the joining member 10 is foamed to form the foam 7, the load and energy required for separation can be reduced compared to when the joining portion 5 of the joining member 10 is separated without foaming.

[0033] <How to make metal foam> The foaming agent sheet described above can be used to produce a metal foam. Specifically, a first metal member, the foaming agent sheet described above, and a second metal member are laminated in this order, and then friction stir welding is performed so as to include the foaming agent sheet to obtain a precursor containing at least a part of the first metal member, at least a part of the foaming agent sheet, and at least a part of the second metal member, and the precursor is heated to produce a metal foam. That is, another embodiment of the present invention is a method for producing a metal foam, which includes a step of laminating a first metal member, a foaming agent sheet, and a second metal member in this order, a step of obtaining a precursor containing at least a part of the first metal member, at least a part of the foaming agent sheet, and at least a part of the second metal member by friction stir welding so as to include the foaming agent sheet, and a step of heating the precursor to obtain a metal foam, and the foaming agent sheet contains a metal, a foaming agent, and other components (e.g., a thickener) as necessary.

[0034] Examples of the material of the first metal member include aluminum, copper, iron, magnesium, titanium, nickel, and zinc. 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 metal 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.

[0035] The material of the second metal member may be the same as that of the first metal member. From the viewpoint of not changing the properties of the members, the material of the second metal member may be substantially the same as the material of the first metal member.

[0036] The shapes of the first metal member and the second metal member are not particularly limited, and the first metal member and the second metal member may each have the same shape.

[0037] In the step of laminating the first metal member, the foaming agent sheet, and the second metal member in this order, a plurality of foaming agent sheets may be used. For example, a plurality of foaming agent sheets may be arranged side by side on the first metal member, or a plurality of foaming agent sheets may be arranged in a stack on the first metal member.

[0038] The first metal member, the foaming agent sheet, and the second metal member are laminated in this order, and then friction stir welding is performed so as to include the foaming agent sheet. The description regarding the friction stir welding in the manufacturing method of the above-mentioned joined member can be applied to the friction stir welding.

[0039] In this way, a precursor containing at least a part of the first metal member, at least a part of the foaming agent sheet, and at least a part of the second metal member can be obtained by friction stir welding the first metal member, the foaming agent sheet, and the second metal member. That is, the precursor is a metal member containing at least the metal contained in the first metal member (first metal), the metal contained in the second metal member (second metal), the metal contained in the foaming agent sheet (third metal), and the foaming agent.

[0040] By heating the precursor, the foaming agent contained in the precursor is decomposed, and the precursor is foamed. This allows a metal foam to be obtained. Examples of heat sources for heating the precursor include a light source that irradiates infrared rays (e.g., a halogen lamp) and a heater. Heating of the precursor may be terminated when the metal foam has sufficiently expanded, or may be terminated when a certain time has elapsed since the start of heating. EXAMPLES

[0041] 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.

[0042] Example 1 [Preparation of foaming agent sheet] Aluminum powder (average particle size 20 μm) was prepared as the metal powder, titanium hydride powder (TiH2, average particle size 45 μm or less) was prepared as the foaming agent powder, and alumina powder (Al2O3, average particle size 1 μm) 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 final precursor (mass of the region stirred by FSW).

[0043] 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.

[0044] [Making metal foam] As shown in FIG. 3, a joining member was produced by FSW using a foaming agent sheet. First, as shown in FIG. 3(a), three foaming agent sheets were arranged in a 20 mm x 60 mm area in the approximate center of an aluminum plate (industrially pure aluminum A1050, 80 mm x 210 mm, thickness 3 mm), and a similar aluminum plate was placed on top of them to obtain a laminate. Next, as shown in FIG. 3(b), an FSW tool (steel, shoulder diameter 17 mm, probe length 4.8 mm, probe diameter 6 mm, with screw) was scanned over the laminate to perform friction stir welding. The tool rotation speed during friction stir welding was 2200 rpm, and the tool scanning speed was 100 mm / min. For friction stir welding, the tool was shifted 5 mm toward the short axis side of the laminate and scanned, and this operation was performed four times. Next, after scanning the tool four times, the scanned area was scanned again to obtain a laminate. A precursor measuring 15 mm×15 mm and 6 mm thick was cut out from the friction stir welded portion of the resulting laminate.

[0045] The prepared precursor was heated by irradiation with light from a halogen lamp, and the foaming agent was decomposed to obtain a metal foam. At this time, the distance between the halogen lamp and the precursor was 80 mm, and the output of the halogen lamp was 1600 W. The density of the obtained metal foam was calculated by Archimedes' method, and the porosity (the volume ratio of pores to the total volume of the metal foam) was calculated from the density of the aluminum plate material. X-ray CT imaging of the obtained metal foam confirmed the presence of pores inside the metal foam.

[0046] Example 2 [Production of joining members] FIG. 4 shows a schematic diagram of a method for producing a joint member. First, as shown in FIG. 4(a), the foaming agent sheet produced in Example 1 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 the 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 FIG. 4(b), the friction stir welding was performed by scanning the tool so that the side of the probe entered the steel SS400 rolled plate material side 0.8 mm from the joint interface. Next, after removing burrs generated by the tool scanning by milling, a joint member having a size of 20 mm x 160 mm and a thickness of 5 mm was produced using a wire electric discharge machine, centered on the joint, as shown in FIG. 5.

[0047] [Separation of jointed parts] The joints of the prepared joint members were heated by irradiation with light 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 80 mm, and the output of the halogen lamp was 1600 W. Heating with the halogen lamp was stopped when the joints had sufficiently expanded. Next, in order to deform the area around the joints of the joint members during the four-point bending test, both ends of the joint members were fixed with U-shaped steel bars filled with structural adhesive. At this time, the distance between the U-shaped steel bars was 25 mm (Figure 6(a)).

[0048] The separation of the bonded members was carried out by a four-point bending test. The conditions were: distance between load points 50 mm, distance between supports 110 mm, and crosshead speed 1 mm / min. The four-point bending test was carried out while checking the relationship between load and displacement. As the displacement increased, the load first increased, and then cracks appeared in the foam at the bonded interface near the maximum load (maximum separation load). The load gradually decreased as the cracks progressed. The load-displacement curve obtained at this time is shown in Figure 7. From the load-displacement curve, it was found that the maximum separation load when the bonded members were separated was 204 N, and the separation energy (the amount of energy required to reach the maximum separation load from the displacement) was 0.157 J. Images of the bonded members immediately after separation are shown in Figures 6(b) and (c).

[0049] Comparative Example 1 A joint member was produced in the same manner as in Example 2. Next, a four-point bending test was carried out while checking the relationship between load and displacement without foaming the joint of the joint member. First, the load increased as the displacement amount increased, and then the load further increased accompanied by deformation of the members. Then, near the maximum load (maximum separation load), the joint broke. The load-displacement curve obtained at this time is shown in FIG. 8. From the load-displacement curve, it was found that the maximum separation load when the joint members were separated was 628N, and the separation energy (the amount of energy from the displacement to the maximum separation load) was 1.469J.

[0050] Example 3 Alumina powder (average particle size 1 μm) in the amount shown in Table 1 was added to molten aluminum obtained by melting a pure aluminum A1050 sheet material, and the mixture was heated while stirring. Then, titanium hydride powder (average particle size 45 μm or less) in the amount shown in Table 1 was added, and the mixture was stirred for 1 minute. Then, the mixture containing aluminum, alumina, and titanium hydride was rolled to obtain foaming agent sheets of Samples No. 1 to 3. Using the foaming agent sheets of Samples No. 1 to 3 obtained, bonding members were obtained in the same manner as in Example 2. After foaming the joints of the bonding members obtained using the foaming agent sheets of Samples No. 1 to 3, a four-point bending test was performed, and the bonding members could be easily separated with a low load.

[0051] [Table 1] [Explanation of symbols]

[0052] 1...first member, 2...second member, 3,13,33...foam sheet, 4,14,34...tool, 5,15,25...joint, 6...heat source, 7...foam, 8...air hole, 10,20...joint member, 11...aluminum plate, 21,31...industrially pure aluminum A1050 rolled plate, 22,32...steel SS400 rolled plate.

Claims

1. Contains a metal and a foaming agent, A foaming agent sheet used to bond components together.

2. The foam sheet of claim 1 , wherein the metal comprises aluminum.

3. The foaming agent sheet of claim 1 , wherein the foaming agent comprises titanium hydride.

4. 10. The foaming agent sheet of claim 1 further comprising a thickening agent.

5. The foam sheet of claim 4 , wherein the thickening agent comprises alumina.

6. 2. The foaming agent sheet of claim 1, having a thickness of 5 mm or less.

7. A method for manufacturing a foaming agent sheet, comprising a step of sintering a metal powder and a powdered foaming agent by a spark plasma sintering method.

8. mixing the molten metal with a foaming agent to obtain a mixture; forming the mixture into a sheet; A method for producing a foaming agent sheet comprising the steps of:

9. laminating a first metal member, a foaming agent sheet, and a second metal member in this order; A step of obtaining a precursor including at least a portion of the first metal member, at least a portion of the foaming agent sheet, and at least a portion of the second metal member by friction stir welding so as to include the foaming agent sheet; heating the precursor to obtain a metal foam; Equipped with The foaming agent sheet comprises a metal and a foaming agent.

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