Metal material and methods for producing metal material

Abstract

Metal material (1), comprising: a basic material (2); an oxide layer (3) arranged on a surface of the base material (2); and a metal layer (4) arranged on a surface of the oxide layer (3), wherein the base material (2) contains aluminium, the oxide layer (3) contains aluminium, nickel and oxygen, the metal layer (4) contains nickel, and the average thickness of the oxide layer (3) is not less than 50 nm and not more than 250 nm, wherein the oxide layer (3) contains a plurality of dispersed pores (35).

Description

TECHNICAL AREA

[0001] The present invention relates to a metal material and a method for producing the metal material. BACKGROUND

[0002] WO 2018 / 124116 A1 discloses a surface-treated material comprising an electrically conductive substrate, a surface treatment coating film formed on the electrically conductive substrate, and an intermediate layer arranged between the electrically conductive substrate and the surface treatment coating film. The electrically conductive substrate is made of aluminum or an aluminum alloy. The surface treatment coating film is made of nickel or the like. An intermediate layer contains a metal component in the electrically conductive substrate, a metal component in the surface treatment coating film, and an oxygen component. The average thickness of the intermediate layer is not less than 1 nm and not more than 40 nm when measured in the vertical cross-section of the surface-treated material.

[0003] US 2009 / 0027832A1 relates to a solid electrolytic capacitor comprising a cathode foil and a solid electrolyte made of conductive polymer. This cathode foil is produced by depositing a nickel layer onto the surface of a base material made of valve metal. This nickel layer comprises a layer containing only nickel and a layer containing nickel oxide.

[0004] JP 2019-206740A describes a surface-coated component comprising a metallic base material, a coating material that coats a surface of the metallic base material, and a mixed layer located between the metallic base material and the coating material. The metallic base material consists of iron, aluminum, or copper. The coating material contains a second metal atom that differs from a first metal atom that forms the base material. SUMMARY OF THE INVENTION

[0005] The metal material of the present disclosure is defined in claim 1.

[0006] The method for producing a metal material according to the present disclosure is defined in claim 16 and comprises: Providing a base material containing aluminum; Arranging a precursor layer containing aluminum and nickel on a surface of the base material; Arranging a metal layer containing nickel on a surface of the precursor layer; and Applying heat treatment to the base material on which the precursor layer and the metal layer are arranged, at a temperature of not less than 400 °C and not more than 600 °C, to transform the precursor layer into an oxide layer containing aluminum, nickel, and oxygen, wherein The arrangement of the precursor layer includes: Forming a thin film containing aluminum oxide on the surface of the base material; and Applying electroless plating to the base material on which the thin film is formed, using a nickel plating solution with a pH of more than 9 and less than 11 at 25°C. BRIEF DESCRIPTION OF DRAWINGS Fig. Figure 1 is a cross-sectional view that schematically shows a part of the metal material in one embodiment. Fig. Figure 2 is an explanatory diagram illustrating the arrangement of a precursor layer in a process for producing a metal material according to one embodiment. Fig. Figure 3 is a cross-sectional view which schematically shows a part of a first coating material which is obtained by arranging a precursor layer in the process for producing a metal material according to an embodiment. Fig. Figure 4 is an explanatory diagram illustrating the application of heat treatment in the process for producing a metal material according to one embodiment. DETAILED DESCRIPTION [Problem to be solved by the present disclosure]

[0007] A further improvement in heat resistance is desired for a metal material in which the surface of the aluminum-containing base material is coated with the nickel-containing metal layer. In the technology disclosed in WO 2018 / 124116 A1, even if close adhesion between the base material and the metal layer is ensured by the intermittent layer, the metal layer can flake off in a high-temperature environment of, for example, not less than 300 °C.

[0008] Accordingly, one objective of the present disclosure is to provide a metallic material with excellent heat resistance. Additionally, another objective of the present disclosure is to provide a method for producing a metallic material that can provide a metallic material with excellent heat resistance. [Beneficial effects of the present disclosure]

[0009] The metallic material of the present disclosure exhibits excellent heat resistance. The process for producing a metallic material according to the present disclosure can provide a metallic material of excellent heat resistance. [Description of embodiments]

[0010] First, embodiments of the present disclosure are listed and described.

[0011] (1) the metallic material of the present disclosure comprises: a basic material; an oxide layer arranged on a surface of the base material; and a metal layer arranged on a surface of the oxide layer, wherein the base material contains aluminium the oxide layer contains aluminium, nickel and oxygen, the metal layer contains nickel, and the average thickness of the oxide layer is not less than 50 nm and not more than 250 nm.

[0012] Because the oxide layer is at least 50 nm thick, the mutual diffusion of aluminum contained in the base material and nickel contained in the metal layer can be suppressed even in a high-temperature environment of at least 300 °C. Because the mutual diffusion of aluminum and nickel can be suppressed, the formation of a Kirkendall void in a surface layer region of the base material can be suppressed. Because the formation of a Kirkendall void can be suppressed, the metal material of the present disclosure exhibits excellent thermal resistance. Thermal resistance, as used herein, refers to how difficult it is for the metal layer to peel off when heat is applied to the metal material.On the other hand, because the oxide layer is no more than 250 nm thick, a reduction in the bendability of the metal material can be suppressed. Bending machinability, as used here, refers to how difficult it is for the metal layer to peel off when bending work is applied to the metal material.

[0013] (2) In an example of the metallic material of the present disclosure The oxide layer can include: a base layer arranged on one side of the base material; and a composite layer arranged on a metal layer side, wherein the base layer may have a higher content of aluminum than of nickel, and the composite layer may have a higher content of nickel than of aluminum.

[0014] Because the oxide layer has a two-layer structure consisting of a base layer and a composite layer, the close adhesion between the base material and the metal layer is simply improved.

[0015] (3) In an example of the metal material of the present disclosure, in which the oxide layer comprises a base layer and a composite layer, The base layer cannot contain less than 30 atomic percent and not more than 60 atomic percent of aluminum.

[0016] Because the content of aluminum contained in the base layer meets the above range, the close adhesion between the base material and the oxide layer is simply improved, and correspondingly, the close adhesion between the base material and the metal layer is simply improved.

[0017] (4) In an example of the metal material of the present disclosure, in which the oxide layer comprises a base layer and a composite layer, The composite layer must contain no less than 30 atomic percent and no more than 70 atomic percent of nickel.

[0018] Because the nickel content contained in the composite layer meets the above range, the close adhesion between the oxide layer and the metal layer is simply improved, and correspondingly, the close adhesion between the base material and the metal layer is simply improved.

[0019] (5) In an example of the metal material of the present disclosure, in which the oxide layer comprises a base layer and a composite layer, The average thickness of the base layer cannot be less than 30 nm and cannot be more than 230 nm.

[0020] Because the average thickness of the base layer is at least 30 nm, the close adhesion between the base material and the oxide layer is improved, and similarly, the close adhesion between the base material and the metal layer is also improved. Furthermore, because the average thickness of the base layer is no more than 230 nm, the thickness of the composite layer can be relatively ensured to a certain extent.

[0021] (6) In an example of the metal material of the present disclosure, in which the oxide layer comprises a base layer and a composite layer, The average thickness of the composite layer cannot be less than 20 nm and cannot be more than 220 nm.

[0022] Because the average thickness of the composite layer is no less than 20 nm, the close bond between the oxide layer and the metal layer is slightly improved, and correspondingly, the close bond between the base material and the metal layer is also slightly improved. On the other hand, because the average thickness of the composite layer is no more than 220 nm, the thickness of the base layer can be relatively ensured to a certain extent.

[0023] (7) In an example of the metal material of the present disclosure in which the oxide layer comprises a base layer and a composite layer, the composite layer may comprise: a multitude of protrusions that jut out from the base layer; and a metal area inserted between the adjacent projections of the same, wherein Each of the numerous protrusions may contain aluminum and oxygen, and the metal area may contain nickel.

[0024] Because the metal area contains nickel, the close adhesion to the metal layer is high. Because the metal area is inserted between the numerous protrusions, the close adhesion between the metal area and the protrusions is high due to the anchoring effect, and consequently, the close adhesion between the composite layer and the metal layer is high. Therefore, because the composite layer is composed of a composite of the protrusion and the metal area, the close adhesion between the oxide layer and the metal layer is enhanced, and consequently, the close adhesion between the base material and the metal layer is also enhanced.

[0025] (8) In an example of the metallic material of the present disclosure The interface where the base material and the oxide layer are in contact with each other can be shaped in an irregular form.

[0026] Because the interface is formed in an irregular shape, the close adhesion between the base material and the oxide layer is simply improved by the anchoring effect, and correspondingly the close adhesion between the base material and the metal layer is simply improved.

[0027] (9) The oxide layer of the metal material of the present invention includes a plurality of dispersed pores.

[0028] Because a large number of pores are dispersed in the oxide layer, the bendability of the metal material is significantly improved. It should be noted that these pores do not substantially affect the heat resistance, unlike Kirkendall voids, which can form in a surface layer region of the base material through mutual diffusion of the metallic element that constitutes the metal material.

[0029] (10) In an example of the metal material of the present disclosure, which has a plurality of pores in the oxide layer, The size of the pores cannot be less than 1 nm and cannot be more than 50 nm.

[0030] Because the pore size is less than 1 nm, the bending machinability of the metal material is significantly improved. Conversely, because the pore size is no more than 50 nm, brittle fracture is suppressed.

[0031] (11) In an example of the metallic material of the present disclosure The average thickness of the metal layer is not less than 3 µm and not more than 15 µm.

[0032] Because the average thickness of the metal layer is no less than 3 µm, the heat resistance is slightly improved. Conversely, because the average thickness of the metal layer is no more than 15 µm, the machinability of the metal material is slightly improved.

[0033] (12) In an example of the metallic material of the present disclosure The base material can be a rolled wire rod, whereby The diameter of the wire rod cannot be less than 0.04 mm and cannot be greater than 5 mm.

[0034] As described above, the metal material of this disclosure is not only of excellent heat resistance but also of excellent machinability. Therefore, the metal material of this disclosure can be suitably used for wire rod, which is often subjected to bending before use. Because the diameter of the wire rod is not less than 0.04 mm, the strength of the base material is easily maintained, and a metal material with excellent machinability can be readily obtained. On the other hand, because the diameter of the wire rod is not more than 5 mm, the machinability of the metal material is significantly improved.

[0035] (13) In an example of the metallic material of the present disclosure The base material can be rolled wire, and The ratio of the average thickness of the oxide layer to the diameter of the base material cannot be less than 0.00005 and cannot be more than 0.0025.

[0036] Because the above ratio is not less than 0.00005, the thickness of the oxide layer is ensured to a certain extent, and the heat resistance is improved. Conversely, because the above ratio is not greater than 0.0025, the thickness of the oxide layer is not excessive, and the machinability of the metal material is improved.

[0037] (14) In an example of the metallic material of the present disclosure The base material can be rolled wire, and The ratio of the average thickness of the metal layer to the diameter of the base material cannot be less than 0.003 and cannot be greater than 0.075.

[0038] Because the above ratio is not less than 0.003, the thickness of the metal layer is ensured to a certain extent, and the heat resistance is improved. Conversely, because the above ratio is not greater than 0.075, the thickness of the metal layer is not excessive, and the bendability of the metal material is improved.

[0039] In an example of the metal material of the present disclosure, in which the oxide layer comprises a base layer and a composite layer, The base material can be made from an aluminum alloy containing a doped element, and The base layer can contain the doped element.

[0040] Because the base material is made of an aluminum alloy, its strength can be improved, and consequently, the strength of the metal layer can be improved. Because the metal is contained within the base layer, the bond between the base material and the oxide layer is enhanced.

[0041] (16) In an example of the metal material of the present disclosure, the oxide layer can contain not less than 20 atomic % and not more than 55 atomic % oxygen.

[0042] Because the oxygen content contained in the oxygen layer meets the above range, the close adhesion between the base material and the metal layer is slightly improved.

[0043] (17) The process for producing a metal material according to one aspect of the present disclosure comprises: Providing a base material containing aluminum; Arranging a precursor layer containing aluminum and nickel on a surface of the base material; Arranging a metal layer containing nickel on a surface of the precursor layer; and Applying a heat treatment to the base material on which the precursor layer and the metal layer are arranged, at a temperature of not less than 400 °C and no more than 600 °C to transform the precursor layer into an oxide layer containing aluminum, nickel and contains oxygen, whereby The arrangement of a precursor layer includes: Formation of a thin film containing aluminum oxide on the surface of the base material; and Applying electroless plating to the base material on which the thin film is formed, using a nickel plating solution with a pH of more than 9 and less than 11 at 25°C.

[0044] When applying a precursor layer, a precursor layer containing a large amount of metal hydroxide can be deposited on the surface of the base material by electroless plating using an alkaline nickel plating solution with a relatively high pH. By depositing a metal layer on the surface of the precursor layer and then applying heat treatment, an oxide layer can be formed in which the metal hydroxide contained in the precursor layer is converted into a metal oxide. Because the heat treatment temperature is not lower than 400 °C, the metal hydroxide is readily converted into the metal oxide. Furthermore, because the heat treatment temperature is not lower than 400 °C, the average thickness of the resulting oxide layer is easily achieved, reaching at least 50 nm.On the other hand, because the heat treatment temperature does not exceed 600 °C, the average thickness of the oxide layer formed is easily adjusted to no more than 250 nm. Thus, according to the process for producing a metal material described above, a metal material can be obtained that comprises a base material, an oxide layer deposited on the surface of the base material, and the metal layer deposited on the surface of the oxide layer. In particular, by applying electroless plating using an alkaline nickel plating solution with a relatively high pH to deposit the precursor layer, and then applying heat treatment at a specific temperature, an oxide layer that is relatively thick, with an average thickness of no less than 50 nm and no more than 250 nm, is easily obtained. [Details of embodiments of the present disclosure]

[0045] The details of the embodiments of the present disclosure are described below with reference to the drawings. Each figure illustrates a form in which a metal material 1 is built up by a rolled wire. The metal material 1 shown in each figure is illustrated by a cross-section obtained by cutting it along a plane parallel to the longitudinal direction of the rolled wire. Fig. 1, Fig. 3 and Fig. Figure 4 shows only one half of the metal material 1 in the radial direction in the cross-section of the metal material 1, but the other half has the same structure. Fig. 1, Fig. 3 and Fig. 4. For clarity, the thickness of the oxide layer relative to the base material is exaggerated and differs from the actual size. Additionally, in Fig. 1, Fig. 3 and Fig. 4. The structure of the composite layer containing the oxide layer is shown schematically for clarity. The same reference symbols in the figures indicate the same names. <metallmaterial>

[0046] As in Fig. As shown in Figure 1, the metal material 1 of the embodiment comprises a base material 2, an oxide layer 3 arranged on the surface of the base material 2, and a metal layer 4 arranged on the surface of the oxide layer 3. The base material 2 contains aluminum. The oxide layer 3 contains aluminum, nickel, and oxygen. The metal layer 4 contains nickel. One of the features of the metal material 1 of the embodiment is that the average thickness of the oxide layer 3 is not less than 50 nm and not greater than 250 nm. Details of the metal material 1 are described below.

[0047] The direction in which the oxide layer 3 and the metal layer 4 are arranged with respect to the base material 2 can be called a lamination direction. The lamination direction is a direction which, if a cross-section of the metal material 1 is taken such that the surface of the base material 2 is a straight line, is orthogonal to the straight line.

[0048] If the base material 2 is a wire rod, the lamination direction is the radial direction of the wire rod. If the base material 2 is a sheet material, the lamination direction is its thickness direction. The lamination direction is the vertical direction in Fig. 1. [Basic material]

[0049] Base material 2 is made of aluminum or an aluminum alloy. “Aluminum (Al)”, as used herein, refers to pure aluminum containing not less than 99 wt% of A1. Pure A1 can be, for example, 1000 series aluminum as specified in JIS H 4000 (2014). 1000 series aluminum can be A1070. “Aluminum (Al) alloy”, as used herein, refers to an aluminum-based alloy containing not less than 50 wt% and preferably not less than 90 wt% Al, and containing at least one dopant other than Al. Examples of dopants in the Al alloy include iron (Fe), magnesium (Mg), silicon (Si), copper (Cu), zinc (Zn), nickel (Ni), manganese (Mn), silver (Ag), chromium (Cr), and zirconium (Zr).The total content of the dopants should be not less than 1 wt% and not less than 50 wt%, and furthermore not less than 1 wt% and not less than 10 wt%. If Mg is included as the dopant, its content must be not less than 0.4 wt% and not more than 5 wt%. Various alloys can be used as such an aluminum alloy, for example, a 5000 series aluminum alloy specified in JIS H 4000 (2014). A5052 can be used as a 5000 series aluminum alloy. The base material 2 can be a forged or cast material.

[0050] The form of the base material 2 can be wire rod, sheet material, bar material, tube, film, or any other desired shape. In this example, the base material 2 is wire rod. Various dimensions of the base material 2 can be selected depending on the intended use.

[0051] The average thickness of the base material 2 must be no less than 0.04 mm and no more than 5 mm. If the base material 2 is wire rod or bar stock, the average thickness is based on its diameter. If the base material 2 is a tube, the average thickness is half the difference between the inner and outer diameters. If the average thickness of the base material 2 is no less than 0.04 mm, the strength of the base material is easily maintained, and a metal material 1 with excellent bending strength is readily obtained. Conversely, if the average thickness of the base material 2 is no more than 5 mm, the bending machinability of the metal material 1 is slightly improved. The average thickness of the base material 2 should be no less than 0.1 mm and no more than 3 mm, and specifically no less than 0.5 mm and no more than 2 mm.

[0052] The surface of the base material 2 on which the oxide layer 3 is arranged can be a substantially flat plane. A substantially flat plane means a surface condition in which the roughness is no more than 1 / 3 of the difference in roughness between a projection 321 and a depression 322 in a composite layer 32 described later. The difference in roughness between projection 321 and depression 322 can be considered the thickness of the composite layer 32. If the surface of the base material 2 on which the oxide layer 3 is arranged is a flat plane, its surface roughness may be no more than 1 / 4, and in particular no more than 1 / 5, of the difference in roughness described above.The surface condition with regard to the roughness of the surface of the base material 2 on which the oxide layer 3 is arranged can be measured by cross-sectional observation using a scanner electron microscope (SEM).

[0053] The surface of the base material 2, on which the oxide layer 3 is arranged, can have a non-uniform shape. A non-uniform shape means a surface condition in which the roughness is greater than 1 / 3 of the difference in unevenness between the projection 321 and the depression 322 in the composite layer 32 described later. When the surface has a non-uniform shape, the oxide layer 3 is arranged such that it fits into the projection and depression of the surface. That is, the interface where the base material 2 and the oxide layer 3 are in contact with each other has a non-uniform shape. When the interface has a non-uniform shape, the close adhesion between the base material 2 and the oxide layer 3 can be easily improved by the anchoring effect.If the surface of the base material 2 on which the oxide layer 3 is arranged is formed in the uneven shape, the surface can no longer have more than 1 / 2 of the above difference in unevenness and in particular almost the same. oxide layer

[0054] The oxide layer 3 is arranged on the surface of the base material 2. The oxide layer 3 contains aluminum, nickel, and oxygen. The oxide layer 3 is mainly composed of aluminum oxide. The oxide layer 3 comprises a base layer 31 and the composite layer 32. The oxide layer 3 of the present example has a two-layer structure consisting of the base layer 31 and the composite layer 32.

[0055] The oxygen content contained in oxide layer 3 must be no less than 20 atomic percent and no more than 55 atomic percent, furthermore no less than 22 atomic percent and no more than 45 atomic percent, and in particular no less than 25 atomic percent and no more than 35 atomic percent. If the oxygen content contained in oxide layer 3 meets the above range, the close adhesion between the base material 2 and the metal layer 4 will be slightly improved. <basisschicht>

[0056] The base layer 31 is arranged on the side of the base material 2. The base layer 31 has a higher aluminum content than that of nickel. Because the base layer 31 contains a large amount of aluminum, the close adhesion between the base material 2 and the oxide layer 3 is slightly improved. The aluminum content contained in the base layer 31 may be not less than 30 atomic percent and not more than 60 atomic percent, furthermore not less than 35 atomic percent and not more than 55 atomic percent, and particularly not less than 40 atomic percent and not more than 50 atomic percent. If the aluminum content contained in the base layer 31 meets the above range, the close adhesion between the base material 2 and the oxide layer 3 is slightly improved. If the base material 2 is made of an aluminum alloy, the base layer 31 preferably contains a dopant element contained in the aluminum alloy. The base layer 31 is mainly made of aluminum oxide.

[0057] The average thickness of the base layer 31 must be at least 30 nm and no more than 230 nm. If the average thickness of the base layer 31 is at least 30 nm, the close adhesion between the base material 2 and the oxide layer 3 is slightly improved. On the other hand, if the average thickness of the base layer 31 is no more than 230 nm, the thickness of the composite layer 32 can be relatively ensured to a certain extent. Furthermore, the average thickness of the base layer 31 must be at least 40 nm and no more than 150 nm, and in particular, no less than 50 nm and no more than 100 nm. The average thickness of the base layer 31 can be determined from a SEM image obtained by observing a cross-section of the metal material 1 using a SEM. The magnification of the SEM image should be at least 50,000 ×.In this SEM image, the thickness of the base layer 31 is measured at ten different points, and their average value is taken as the average thickness of the base layer 31. The thickness of the base layer 31 is the length along the lamination direction of each layer from the surface of the base material 2 to the boundary between the base layer 31 and the composite layer 32. The boundary between the base layer 31 and the composite layer 32 will be described later. <kompositschicht>

[0058] The composite layer 32 is arranged on the side of the metal layer 4. The composite layer 32 has a higher nickel content than the aluminum content. Because the composite layer 32 contains a large amount of nickel, the close adhesion between the oxide layer 3 and the metal layer 4 can be easily improved. The nickel content in the composite layer 32 may be not less than 25 atomic percent and not more than 70 atomic percent, further, not less than 32 atomic percent and not more than 60 atomic percent, and in particular, not less than 35 atomic percent and not more than 50 atomic percent. If the nickel content in the composite layer 32 meets the above range, the close adhesion between the oxide layer 3 and the metal layer 4 can be easily improved. The composite layer 32 of the present example consists of a composite of a multitude of protrusions 321 and metal areas 323. projection

[0059] The numerous projections 321 extend from the base layer 31. A depression 332 is arranged between adjacent projections 321. Each projection 321 contains aluminum and oxygen. Each projection 321 is made primarily of aluminum oxide. Each projection 321 has essentially the same composition as the base layer 31.

[0060] The height of the projection 321 is the length along the lamination direction from the boundary between the base layer 31 and the composite layer 32 to the apex of the projection 321. The boundary between the base layer 31 and the composite layer 32 is a line L1, which connects the deepest point of adjacent depressions 322 with a straight line. The height of the projection 321 cannot be less than 20 nm and cannot be more than 220 nm. The metal area 323 exists in the depression 322, which is located between adjacent projections 321. If the height of the projection 321 is not less than 20 nm, the large depression 322 is easily ensured, and a large contact area between the depression 322 and the metal area 323 is easily ensured.Additionally, if the protrusion height of the protrusion 321 is not less than 20 nm, the close adhesion between the protrusion 321 and the metal region 323 can be increased by the anchoring effect. On the other hand, if the protrusion height of the protrusion 321 is not more than 220 nm, the thickening of the composite layer 32 can be suppressed, and the thickness of the base layer 31 can be ensured to a certain extent. The protrusion height of the protrusion 321 may further be not less than 30 nm and not more than 350 nm, and in particular not more than 40 nm and not more than 100 nm. The protrusion height of the protrusion 321 can be determined from a SEM image of the base material, which is obtained by observing a cross-section of metal material 1 using an SEM. The magnification of the SEM image may be not less than 50,000x.In this SEM image, the protrusion heights of no fewer than ten protrusions 321 are measured, and their average value is taken as the protrusion height of protrusions 321. This protrusion height is the length of the straight line drawn from the vertex to the base in the SEM image above, with the straight line running along the lamination direction and passing the vertex and base of protrusions 321.

[0061] The distance between the vertices of adjacent protrusions 321 may also be no less than 5 nm and no more than 80 nm. If the distance between the vertices of adjacent protrusions 321 is no less than 5 nm, a large contact area between material region 323 and the metal layer 4 is easily ensured, and the close adhesion between the oxide layer 3 and the metal layer 4 can be easily improved. On the other hand, if the distance between the vertices of adjacent protrusions 321 is no more than 80 nm, many protrusions 321 and depressions 322 are easily arranged, and the close adhesion between protrusions 321 and metal regions 323 is easily increased by the anchoring effect. The distance between the vertices of adjacent regions 321 may further be no less than 10 nm and no more than 60 nm, and in particular no less than 15 nm and no more than 40 nm. <metallbereich>

[0062] The metal area 323 is inserted between adjacent projections 321. Each metal area 323 contains nickel. Each metal area 323 is made primarily of simple nickel. The metal area 323 contributes to improving the close adhesion to the metal layer 4. The metal area 323 is typically located in a region formed by a line L2 connecting the vertices of adjacent projections 321 and depression 322.

[0063] The average thickness of the composite layer 32 should be no less than 20 nm and no more than 220 nm. If the composite layer 32 is formed by a composite of protrusion 321 and metal area 323, the average thickness of the composite layer 32 corresponds to the protrusion height of the protrusion 321. If the average thickness of the composite layer 32 is no less than 20 nm, the close adhesion between the oxide layer 3 and the metal layer 4 is slightly improved. On the other hand, if the average thickness of the composite layer 32 is no greater than 220 nm, the thickness of the base layer 31 can be relatively ensured to some extent. The average thickness of the composite layer 32 should be no less than 40 nm and no more than 150 nm, and in particular, no less than 50 nm and no more than 100 nm.The average thickness of the composite layer 32 can be determined from a SEM image obtained by observing a cross-section of metal material 1 using a SEM. The magnification of the SEM image can be 50,000x. In this SEM image, the thickness of the composite layer 32 is measured at ten different points, and their average value is used as the average thickness of the composite layer 32. The thickness of the composite layer 32 is the protrusion height of protrusion 321. <durchschnittsdicke>

[0064] The average thickness of oxide layer 3 is not less than 50 nm and not more than 250 nm. Because oxide layer 3 is not less than 50 nm thick, mutual diffusion of aluminum contained in the base material 2 and nickel contained in the metal layer 4 can be suppressed, even in a high-temperature environment of not less than 300 °C. Because mutual diffusion of aluminum and nickel can be suppressed, the formation of a Kirkendall void in a surface layer region of the base material 2 can be suppressed. Because the formation of a Kirkendall void can be suppressed, the metal material 1 exhibits excellent heat resistance. Furthermore, because oxide layer 3 is not more than 250 nm thick, a reduction in the machinability of the metal material 1 can be suppressed.The average thickness of oxide layer 3 can be no less than 75 nm and no more than 200 nm, no less than 100 nm and no more than 150 nm, and in particular more than 100 nm and no more than 150 nm.

[0065] The average thickness of oxide layer 3 can be determined from a SEM image obtained by observing a cross-section of metal material 1 using a scanner electron microscope (SEM). The magnification of the SEM image can be up to 50,000x. In this SEM image, the thickness of oxide layer 3 is measured at ten different points, and their average value is taken as the average thickness of oxide layer 3. The thickness of oxide layer 3 is the length in the lamination direction between the interface between base material 2 and oxide layer 3 at the interface between oxide layer 3 and metal layer 4. If oxide layer 3 has a two-layer structure consisting of base layer 31 and composite layer 32, the thickness of oxide layer 3 is the sum of the thicknesses of base layer 31 and composite layer 32.

[0066] If the base material 2 is a rolled wire rod, the ratio of the average thickness of the oxide layer 3 to the diameter of the base material 2 must be no less than 0.0005 and no more than 0.0025. If the above ratio is no less than 0.00005, the thickness of the oxide layer 3 is ensured to a certain extent, and the heat resistance can be slightly improved. Conversely, if the above ratio is no more than 0.0025, the thickness of the oxide layer 3 is not excessive, and the machinability of the metal material 1 is slightly improved. Furthermore, the above ratio must be no less than 0.00008 and no more than 0.001, and specifically no less than 0.00012 and no more than 0.0002. Miscellaneous

[0067] The oxide layer 3 contains a multitude of distributed pores 35. The pores 35 are distributed and mainly present in the base layer 31 and the projections 321. When the multitude of pores 35 are distributed in the oxide layer 3, the machinability of the metal material 1 is slightly improved. The size of the pores 35 must be at least 1 nm and no more than 50 nm. If the size of the pores 35 is not less than 1 nm, the machinability of the metal material 1 is slightly improved. Conversely, if the size of the pores 35 is not greater than 50 nm, brittle fracture is suppressed. Furthermore, the size of the pores 35 must be no less than 5 nm and no greater than 40 nm, and in particular, no less than 10 nm and no greater than 30 nm. The size of pores 35 can be derived from a SEM image of the base material obtained by observing a cross-section of metal material 1 using a SEM.The SEM image can be magnified up to 50,000x. In this SEM image, the equivalent circular diameter of pore 35 is used as the diameter, and the average diameter of at least 10 pores 35 is used as the pore size. The equivalent circular diameter, as used here, refers to the diameter of a perfect circle with an area equal to the cross-sectional area of ​​pore 35.

[0068] The area ratio of the pores 35 to the oxide layer 3 in the cross-section of the metal material 1 must be no less than 1% and no more than 20%. If the area ratio is no less than 1%, the machinability of the metal material 1 is slightly improved. Conversely, if the area ratio is no more than 20%, brittle fracture is suppressed. Furthermore, the area ratio must be no less than 3% and no greater than 50%, and in particular, no less than 5% and no greater than 10%. The area ratio can be determined from a SEM image obtained by observing a cross-section of the metal material 1 using a SEM instrument. The magnification of the SEM image can be 50,000x. In this SEM image, the ratio of the total area of ​​the pores 35 to the area of ​​the oxide layer 3 is used as the area ratio described above. <metallschicht>

[0069] Metal layer 4 is located on the surface of oxide layer 3. Metal layer 4 contains nickel. Metal layer 4 is primarily composed of simple nickel.

[0070] The average thickness of metal layer 4 cannot be less than 3 µm and cannot be greater than 15 µm. If the average thickness of metal layer 4 is not less than 3 µm, the heat resistance is slightly improved. Conversely, if the average thickness of metal layer 4 is not more than 15 µm, the machinability of the metal material 1 is slightly improved. Furthermore, the average thickness of metal layer 4 cannot be less than 4 µm and cannot be more than 12 µm, and specifically, not less than 6 µm and not more than 10 µm. The average thickness of metal layer 4 can be determined from a SEM image obtained by observing a cross-section of the metal material 1 using a SEM. The magnification of the SEM image can be 50,000x.In this SEM image, the thickness of metal layer 4 is measured at ten different points, and their average value is used as the average thickness of metal layer 4. The thickness of metal layer 4 is the length in the lamination direction from the surface between oxide layer 3 and metal layer 4 to the surface of metal layer 4. If oxide layer 3 has a two-layer structure consisting of base layer 31 and composite layer 32, the interface between oxide layer 3 and metal layer 4 is a line L2 connecting the vertices of adjacent projections 321 with a straight line.

[0071] If the base material 2 is a rolled wire rod, the ratio of the average thickness of the metal layer 4 to the diameter of the base material 2 must be no less than 0.003 and no greater than 0.075. If the above ratio is no less than 0.003, the thickness of the metal layer 4 is ensured to a certain extent, and the heat resistance is simply improved. If, on the other hand, the above ratio is no more than 0.075, the thickness of the metal layer 4 is not excessive, and the bendability of the metal material 1 is slightly improved. Furthermore, the above ratio must be no less than 0.004 and no greater than 0.04, and specifically no less than 0.005 and no greater than 0.012. <sonstiges>

[0072] The metal material 1 may further contain another metal layer on the surface of the metal layer 4. <anwendungen>

[0073] The metal material 1 of the embodiment can be suitably used for an application involving use in a high-temperature environment and an application involving heat treatment. Examples of such applications include a bump (knob) connecting to an electronic device, a battery supply wire, an electronic device, and an automotive part. <Verfahren zum Herstellen von Metallmaterial>

[0074] The method for producing a metal material according to one embodiment includes providing a base material, depositing a precursor layer, depositing a metal layer, and applying a heat treatment. The following are described with reference to Fig. Sections 2 to 4 describe the details of the process for producing a metal material. <bereitstellung>

[0075] During the provisioning process, a base material 110 containing aluminum is provided. Base material 110 is the same as base material 2 described above. In this example, base material 110 is wire rod. [Arrangement of precursor layer]

[0076] When applying a precursor layer, a precursor layer 130 containing aluminium and nickel is laid on the surface of the base material 110 to prepare a first coating material 100 ( Fig. 3) As in Fig. As shown in Figure 2, the arrangement of a precursor layer involves forming a thin film 120 containing aluminium oxide on the surface of the base material 110 and applying electroless plating to the base material 110 on which the thin film 120 is formed, using a nickel plating solution 300. <Ausbildung von Dünnfilm>

[0077] If the base material 110 contains aluminum, a pretreatment is generally applied to the base material 110 before the plating is applied. The pretreatment includes at least one of degreasing, etching, and pickling. In the present example, degreasing, etching, and pickling are all performed as pretreatments. Degreasing is a treatment that removes the oil adhering to the surface of the base material 110. Degreasing is carried out, for example, using an alkaline degreasing agent. Etching is a treatment that removes the aluminum oxide film formed on the surface of the base material 110. Etching is carried out using, for example, a highly alkaline aqueous solution containing sodium hydroxide or the like. Pickling is a treatment that removes the debris generated during etching.The term "dirt" refers to an impurity containing aluminum hydroxide (Al(OH)3) or an aluminum alloy. Pickling is carried out using, for example, an acidic aqueous solution containing nitric acid or the like.

[0078] The thin film 120 can be obtained by applying the shape described above and also the base material 110. The average thickness of the thin film 120 cannot be less than 1 nm and cannot be more than 10 nm. If the average thickness of the thin film 120 meets the above range, a base layer 131 and a protrusion 1321 ( Fig. 3) originate in a composite layer 132 that forms the basis of the precursor layer 130. The average thickness of the thin film 120 must be no less than 1.5 nm and no more than 7 nm, and in particular no less than 2 nm and no more than 5 nm. The average thickness of the thin film 120 can be measured by elemental analysis in the depth direction using X-ray photoelectron spectroscopy (XPS). <Anwendung von elektroloser Plattierung>

[0079] When using electroless plating, as in Fig. As shown in Figure 2, the base material 110, on which the thin film 120 is formed, is immersed in the nickel plating solution 300. The nickel plating solution 300 has a pH higher than 9 and lower than 11 at 25 °C. By applying electroless plating using an alkaline nickel plating solution 300 with a relatively high pH, ​​the precursor layer 130, which contains a large amount of metal hydroxide ( Fig. 3) are arranged on the surface of the base material 110. The metal hydroxide contained in the precursor layer 130 is converted into a metal oxide by heat treatment described later. Although the details are described later, the precursor layer 130 is transformed into the oxide layer 3 ( Fig. 1) transformed by converting the metal hydroxide into metal oxide. By enclosing a large amount of metal hydroxide in the precursor layer 130, the metal hydroxide can be readily converted into the metal oxide by a heat treatment as described below, and a relatively thick oxide layer 3 can be obtained. The pH of the nickel plating solution 300 must not be lower than 10, and in particular not lower than 10.5.

[0080] The temperature of the nickel plating solution 300 during the electroless plating treatment must not be lower than 20 °C or higher than 100 °C. The treatment time for electroless plating must be no shorter than 1 minute and no longer than 20 minutes, and furthermore no shorter than 2 minutes and no longer than 10 minutes.

[0081] Nickel plating solution 300 contains a nickel compound, which is a source of nickel ions. Examples of nickel compounds include nickel sulfate, nickel chloride, and nickel nitrate. The concentration of the nickel compound must not be lower than 0.1 g / L or higher than 50 g / L.

[0082] Nickel plating solution 300 can contain additives such as a reducing agent, a complexing agent, a pH buffer, a brightening agent, and a surfactant, in addition to a nickel compound. A reducing agent is a compound that reduces a nickel ion. Examples of reducing agents include sodium hypophosphite, a boron compound, and a hydrazine compound. A complexing agent is a compound that forms a complex with a metal ion in nickel plating solution 300 and stabilizes the complex. The complexing agent can be selected appropriately depending on the type of metal salt. Examples of complexing agents include an ammonium salt of sulfuric acid, phosphoric acid, hydrochloric acid, or the like; sulfamic acid; glycine; ethylenediamine; ethylenediaminetetraacetic acid; and an organic carboxylic acid. The pH buffering agent is a compound that prevents the precipitation of a metal ion.Examples of pH buffer materials include boric acid, acetic acid, and citric acid. The brightening agent is a compound that smooths the surface of the resulting layer. Examples of brightening agents include sodium saccharin, sodium naphthalene disulfonate, sodium sulfate, and butynidone. Examples of surfactants include sodium dodecyl sulfate and polyoxyethylene ether. The concentration of the additive is not particularly limited.

[0083] By applying electroless plating, as in Fig. As shown in Figure 3, the first coating material 100, which contains the precursor layer 130 on the surface of the base material 110, can be obtained. The precursor layer 130 has a two-layer structure consisting of a base layer 131 and a composite layer 132. The composite layer 132 consists of a composite of a multitude of protrusions 1321 and metal areas 1323. The mechanism by which such a precursor layer 130 is formed by applying electroless plating is assumed to be as follows.

[0084] First, a portion of the thin film 120 is dissolved by nickel plating solution 300 to expose the surface of the base material 110. On the exposed surface of the base material 110, the aluminum that forms the base material 110 is replaced by nickel. Additionally, the exposed surface of the base material 110 is oxidized. Conversely, the remaining portion of the thin film 120 that has not been dissolved protrudes compared to the dissolved area. Furthermore, this remaining portion of the thin film 120 that has not been dissolved partially grows due to the formation of a new aluminum oxide film or thin film 120. This remaining portion of the thin film 120 that has not been dissolved protrudes compared to the other areas, and these protruding areas serve as the multiple protrusions 1321. The portion of the thin film 120 other than these protrusions serves as the base layer 131.The thin film 120 dissolves and grows, and nickel is deposited in a depression 1322 located between the multiple projections 1321. The nickel deposited in this way, filling the depression 1322, serves as the metal areas 1323.

[0085] The precursor layer 130 consists mainly of a hydroxide. The base layer 131 and projections 1321 are mainly derived from this thin film 120. Therefore, the base layer 131 and projections 1321 are mainly made of aluminum hydroxide. Metal areas 1323 are mainly derived from the nickel compound contained in the nickel plating solution 300. Therefore, metal areas 1323 are mainly made of nickel hydroxide or simple nickel. [Deposition of metal layer]

[0086] During the deposition of a metal layer, a metal layer 140 containing nickel is deposited on the surface of the precursor layer 130 to prepare a second coating material 200 (see Fig. 4) The metal layer 140 can be formed by applying plating. The plating can be electroless plating or electrolytic plating.

[0087] In the case of electroless plating, a known plating solution that allows electroless nickel plating can be used.

[0088] In the case of electrolytic plating, a known nickel plating solution can be used. Examples of nickel plating solutions used for electrolytic plating include a Watts bath containing nickel sulfate, nickel chloride, and boric acid as the main components; a sulfamate bath containing nickel sulfate and boric acid as the main components; a Wood bath containing nickel chloride and hydrochloric acid as the main components; and a black bath containing nickel sulfate, nickel ammonium sulfate, zinc sulfate, and sodium thiocyanate as the main components. The conditions for electroless plating are not particularly restricted. The current density, for example, cannot be less than 0.1 A / dm². 2 and not larger than 20 A / dm² 2 The temperature of the nickel plating solution during the electrolytic plating treatment, for example, must not be lower than 20 °C or higher than 70 °C. The treatment time of the electrolytic plating can be adjusted appropriately depending on the desired thickness.

[0089] By applying a metal layer, the second coating material 200, which contains the metal layer 140 on the surface of the precursor layer 130, can be obtained, as shown in Fig. 4 shown. Metal layer 140 is the same as metal layer 4 described above.

[0090] After applying a metal layer, another metal layer can be formed on the surface of metal layer 140. Examples of the other metal layer include a tin-plated layer. [Heat treatment]

[0091] During heat treatment, a heat treatment is applied to the base material 110, on which the precursor layer 130 and the metal layer 140 are placed, as shown in Fig. 4 shown. This heat treatment converts the metal hydroxide contained in the precursor layer 130 into a metal oxide. This means that this heat treatment transforms the precursor layer 130 into the oxide layer 3 ( Fig. 1) is transformed, which contains aluminum, nickel, and oxygen. Additionally, this heat treatment increases the thickness of the oxide layer 3. It should be noted that this heat treatment does not significantly affect the base material 110 and the metal layer 140. The base material 2 and the metal layer 4 in the metal material 1, which are obtained after the heat treatment, essentially maintain the structure, thickness, and the like of the base material 110 and the metal layer 140 in the manufacturing process.

[0092] The heat treatment temperature is not lower than 400 °C and not higher than 600 °C. Because the heat treatment temperature is not lower than 400 °C, the metal hydroxide contained in the precursor layer 130 is well converted into a metal oxide. Additionally, because the heat treatment temperature is not lower than 400 °C, the average thickness of the oxide layer 3 formed ( Fig. 1) slightly adjusted to not less than 50 nm. On the other hand, because the heat treatment temperature is not higher than 600 °C, the average thickness of the oxide layer formed 3 is slightly adjusted to not more than 250 nm. The heat treatment temperature may further be not lower than 420 °C and not higher than 550 °C, and in particular not lower than 450 °C and not higher than 500 °C.

[0093] The heat treatment time must be at least 30 seconds and no longer than 60 minutes. If the heat treatment time is at least 30 seconds, the metal hydroxide contained in the precursor layer 130 is well converted into a metal oxide. Additionally, if the heat treatment time is at least 30 seconds, the average thickness of the oxide layer formed will be 3 ( Fig. 1) slightly adjusted to not less than 50 nm. On the other hand, if the heat treatment time is not longer than 60 minutes, the average thickness of the oxide layer formed is slightly adjusted to not more than 250 nm. The heat treatment time may further be not shorter than 5 minutes and not longer than 30 minutes, and in particular not shorter than 10 minutes, and not longer than 15 minutes.

[0094] The heat treatment atmosphere can be an inert gas atmosphere such as an argon atmosphere or a nitrogen atmosphere.

[0095] Depending on the heat treatment temperature and heat treatment time described above, samples can be 35 ( Fig. 1) are dispersed and formed on the base layer 31 and / or projections 321 in the metal material 1 obtained after heat treatment. <wirkungen>

[0096] In the metal material 1 of the embodiment, the oxide layer 3 is inserted between the base material 2 and the metal layer 4. The oxide layer 3 comprises aluminum, which is a metal component of the base material 2, nickel, which is a metal component of the metal layer 4, and oxygen. Due to the interposition of the oxide layer 3, the metal material 1 of embodiment 1 exhibits excellent adhesion between the base material 2 and the metal layer 4. In particular, because the oxide layer 3 is at least 50 nm thick, mutual fusion of the aluminum contained in the base material 2 and the nickel contained in the metal layer 4 can be suppressed, even in a high-temperature environment of at least 300 °C. Because the mutual diffusion of aluminum and nickel can be suppressed, the formation of a Kirkendall void in a surface layer region of the base material 2 can be prevented.Because the formation of a Kirkendall void can be suppressed, the metal material 1 of the embodiment exhibits excellent heat resistance. Furthermore, because the oxide layer 3 is no larger than 250 nm, a reduction in the machinability of the metal material 1 can be prevented.

[0097] In the process for producing a metal material according to the embodiment, a precursor layer 130, containing a large amount of metal hydroxide, is applied to the surface of the base material 110, and then a heat treatment is applied. The precursor layer 130, containing a large amount of metal hydroxide, can be obtained by applying electroless plating using an alkaline nickel plating solution with a relatively high pH. The metal hydroxide contained in the precursor layer 130 is converted into a metal oxide by the heat treatment. Because the heat treatment temperature is not lower than 400 °C, the metal hydroxide is thoroughly converted into the metal oxide, and the average thickness of the oxide layer 3 that is formed is easily adjusted to not less than 50 nm.On the other hand, because the heat treatment temperature is not higher than 600 °C, the average thickness of the oxide layer 3 formed is easily adjusted to no more than 250 nm. Thus, according to the method for producing a metal material according to the embodiment, the metal material 1 containing the base material 2, the oxide layer 3 arranged on the surface of the base material 2, and the metal layer 4 arranged on the surface of the oxide layer 3 can be obtained. In particular, by applying electroless plating using an alkaline nickel plating solution with a relatively high pH to arrange the precursor layer 130 and then applying heat treatment at a specific temperature, the oxide layer 3, which is relatively thick and has an average thickness of not less than 50 nm and not more than 250 nm, is easily obtained. [Test examples]

[0098] A metal material containing an aluminum-containing base material, a nickel-containing metal layer, and an oxide layer between the base material and the metal layer was prepared, and the close adhesion in the metal material was investigated. <Testbeispiel 1>

[0099] In test example 1, nickel plating solutions with different pH values ​​were used to arrange a precursor layer, which is the origin of the oxide layer, and the structure and thickness of the resulting oxide layers and their close adhesion to the metal material were investigated. [Preparation of samples] • Sample No. 1-1 to No. 1-5

[0100] First, a wire rod made from A1070 according to a JIS standard was provided as the base material. The diameter of the base material is 5 mm.

[0101] A pretreatment was applied to the provided base material. This pretreatment included degreasing, etching, and descaling. The sample product obtained by applying the pretreatment to the A1070 wire rod was a thin film of aluminum oxide approximately 3 nm thick.

[0102] The base material on which the thin film was formed was immersed in a nickel plating solution for electroless plating. The nickel plating solution contained nickel sulfate hexahydrate and glycine. The concentration of nickel sulfate hexahydrate was 25 g / L, and the concentration of glycine was 30 g / L. The pH of the nickel plating solution at 25 °C was the pH shown in Table 1. This nickel plating solution was maintained at 60 °C, and the base material on which the thin film was formed was immersed for 2 minutes.

[0103] A precursor layer is formed on the surface of the base material through the above pretreatment and electroless plating.

[0104] Next, electrolytic plating was applied to the base material on which the precursor layer had formed, using a Watts bath. The temperature of the Watts bath was 55 °C. The current density of the electrolytic plating was 5 A / dm². 2 The electrolytic plating process was carried out until a metal layer of the desired thickness was formed on the surface of the precursor layer. The average thickness of the metal layer was 15 µm.

[0105] Next, heat treatment was applied to the base material on which the precursor layer and the metal layer had formed. The heat treatment temperature was 600 °C. The heat treatment time was 30 seconds. The heat treatment atmosphere was argon. • Sample No. 1-11 to No. 1-15

[0106] First, a wire rod manufactured from A5052 according to a JIS standard was provided as a base material. The diameter of the base material is 0.2 mm.

[0107] A pretreatment was applied to the provided base material. The pretreatment is the same as for sample no. 1-1 and the like. In the sample product obtained by applying the pretreatment to the wire rod produced from A5052, a thin film of aluminum oxide with a thickness of approximately 3 nm was formed. The base material on which the thin film was formed was immersed in a nickel plating solution for electroless plating. The conditions for the nickel plating solution and the electroless plating are the same as for sample no. 1-1 and the like.

[0108] A precursor layer is formed on the surface of the base material by the above pretreatment and electroless plating.

[0109] Next, electrolytic plating was applied to the base material on which the precursor layer had formed, using a Watts bath. The conditions for the Watts bath and electrolytic plating were the same as for sample No. 1-1 and similar samples. The average thickness of the metal layer was 3 µm.

[0110] Next, heat treatment was applied to the base material on which the precursor layer and the metal layer had formed. The conditions for the heat treatment were the same as for samples No. 1-1 and the like. That is, the heat treatment was carried out at 600 °C for 30 seconds in an argon atmosphere. [Structure and thickness of oxide layer]

[0111] A cross-section of the metal material in each sample was observed using SEM, and the structure was analyzed using energy-dispersive X-ray spectroscopy (EDX). The results confirmed that all samples contained a base layer with a relatively high aluminum content on the base material side and a composite layer with a relatively high nickel content on the metal layer side. The aluminum and nickel content in each layer was determined by performing compositional analysis on five regions within the oxide layer into which each layer fits and using their average values. The aluminum (Al) and nickel (Ni) content in the base layer and the composite layer is shown in Table 1. It should be noted that, although not shown in Table 1, oxygen (O) was also present in the base layer and the composite layer in addition to Al and Ni.Additionally, although not shown in Table 1, magnesium (Mg) was still present in the base layer in the range of not less than 0.4 wt% and not more than 5 wt% in samples No. 1-11 to No. 1-15.

[0112] It was confirmed that the composite layer contained numerous protrusions projecting from the base layer and a metal area inserted into a depression located between adjacent protrusions. The base layer and the protrusions were primarily composed of aluminum oxide. The metal component was mainly nickel. Because the composite layer contains a metal component, the nickel content is higher than that of aluminum.

[0113] The thickness of the base layer and the composite layer were determined as follows. First, in a SEM image, the deepest points of adjacent depressions were connected with a straight line, designated line L1, which served as the boundary between the base layer and the composite layer. Additionally, the vertices of the adjacent protrusions 321 were connected with a straight line, designated line L2, which served as the boundary between the composite layer and the metal layer. The thickness of the base layer was determined by measuring the length in the lamination direction between the surface of the base material and line L1 at ten different points and using the average of these measurements. The thickness of the composite layer was determined by measuring the length in the lamination direction between lines L1 and L2 at ten different points and using the average of these measurements.The thicknesses of the base layer and the composite layer are shown in Table 1. [Near Adhesion Evaluation 1]

[0114] The metal material of each sample obtained was heated at 500 °C for 10 minutes and then cooled to room temperature.

[0115] The heated and cooled material was wound around a stainless steel holder. A wire rod, a round bar, or similar material could be used as the holder. In this example, a variety of wire rods with different diameters were used. The appearance of the metal was observed using a stereo microscope, and the presence or absence of flaking of the metal layer was investigated. Specifically, the diameter of the holder was gradually reduced, and the radius of curvature of the metal was measured when flaking of the metal layer was first confirmed in the metal material wound around the holder. The radius of curvature of the metal is the sum of the radius of the base material and the radius of the holder.The radius of curvature of the metal material, when the peeling of the metal layer is first confirmed, is referred to as the critical radius of curvature for bending machinability. The ratio R / D of the critical radius of curvature (R of the bending radius) to the radius D of the base material was determined. The smaller the ratio RD, the better the near-adhesion. If R / D is not greater than 1, an A rating is given; if R / D is greater than 1 but not greater than 3, a B rating is given; if R / D is greater than 3 but not greater than 5, a C rating is given; and if R / D is greater than 5, a D rating is given. In particular, if R / D is not greater than 0.75, an A+ rating is given. The results are shown in Table 1.

[0116] It should be noted that in the near adhesion evaluation 1, heating at 500 °C was performed for 10 minutes. Therefore, in the near adhesion evaluation 1, excellent near adhesion is equivalent to excellent heat resistance. Additionally, bending was applied to the metal material in the near adhesion evaluation 1. Therefore, in the near adhesion evaluation 1, excellent near adhesion is equivalent to excellent ductility. As shown in Table 1, it is evident that regardless of whether the material is pure aluminum or an aluminum alloy, the result of the close adhesion evaluation 1 is excellent when the average thickness of the oxide layer is not less than 50 nm and not greater than 250 nm. On the other hand, it is evident that samples No. 1-1 and No. 1-11, in which the average thickness of the oxide layer is less than 50 nm, are inferior in the close adhesion evaluation 1. The reason for this can be considered as follows: when the average thickness of the oxide layer was less than 50 nm, aluminum contained in the base material and nickel contained in the metal layer diffused mutually upon heating at 500 °C, leading to the formation of a Kirkendall void in the surface layer region of the base material. Additionally, it is evident that samples No. 1-5 and No.1-15, in which the average thickness of the oxide layer is more than 250 nm, are also inferior in close adhesion. The reason for this can be assumed as follows: if the average thickness of the oxide layer is more than 250 nm, the bendability of the metal material is inferior.

[0117] In particular, it can be seen that samples No. 1-4 and No. 1-14, in which the average thickness of the oxide layer is greater than 100 nm, perform very well in the near-adhesion evaluation 1. The reason for this is assumed to be as follows: if the average thickness of the oxide layer is relatively thick, specifically greater than 100 nm, mutual diffusion between aluminum contained in the base material and nickel contained in the metal layer can be well suppressed, even when heated to 500 °C. The following can be assumed: because the aforementioned mutual diffusion can be suppressed, it is difficult for a Kirkendall void to form in the surface layer region of the base material, and the near-adhesion is excellent.

[0118] Additionally, as shown in Table 1, the average oxide layer thickness depends on the pH of the nickel plating solution. Specifically, it is evident that if the pH of the nickel plating solution is not lower than 9.5, the average oxide layer thickness can be set to no more than 50 nm. For samples No. 1-11 and No. 1-12, in which the base material is made of an aluminum alloy, the average oxide layer thickness is 40 nm when the pH of the nickel plating solution is 9.0, and 60 nm when the pH of the nickel plating solution is 9.5. It can therefore be seen that if the pH of the nickel plating solution is greater than 9.0, the average oxide layer thickness cannot be set to less than 50 nm.On the other hand, it can be seen that if the pH of the nickel plating solution is not greater than 10.5, the average thickness of the oxide layer can be set to no more than 250 nm. For samples No. 1-14 and No. 1-15, in which the base material is made of an aluminum alloy, if the pH of the nickel plating solution is 10.5, the average thickness of the oxide layer is 170 nm, and if the pH of the nickel plating solution is 11.0, the average thickness of the oxide layer is 300 nm. From this, it can be seen that if the pH of the nickel plating solution is lower than 11.0, the average thickness of the oxide layer can be set to no more than 250 nm. <Testbeispiel 2>

[0119] In test example 2, the heat treatment temperature and heat treatment time were varied when applying the heat treatment to convert the precursor layer into an oxide layer, and the structure and thickness of the resulting oxide layer and its close adhesion to the metal material were investigated. [Preparation of samples] • Sample No. 2-1 to No. 2-4

[0120] First, a wire rod manufactured from A5052 according to a JIS standard was provided as the base material. The diameter of the base material is 2 mm.

[0121] A pretreatment was applied to the provided base material. The pretreatment is the same as for sample no. 1-1 and the like.

[0122] The base material from which the thin film was formed was immersed in a nickel plating solution for electroless plating. The nickel plating solution contained nickel sulfate hexahydrate and glycine. The nickel sulfate hexahydrate concentration was 25 g / L, and the glycine concentration was 30 g / L. The pH of the nickel plating solution at 25 °C was 9.5. This nickel plating solution was maintained at 60 °C, and the base material on which the thin film was formed was immersed for 2 minutes.

[0123] A precursor layer was formed on the surface of the base material through the above pretreatment and electroless plating.

[0124] Next, electrolytic plating was applied to the base material on which the precursor layer had formed, using a Watts bath. The conditions for the Watts bath and electrolytic plating were the same as for sample No. 1-1 and similar samples. The average thickness of the metal layer was 7 µm.

[0125] Next, heat treatment was applied to the base material on which the precursor layer and the metal layer had formed. The heat treatment temperature was 400 °C. The heat treatment times were 5 minutes, 10 minutes, 30 minutes, and 60 minutes. The heat treatment atmosphere was argon. The heat treatment temperature and time are shown in Table 2. • Sample No. 2-11 to No. 2-14

[0126] Samples No. 2-11 to No. 2-14 were the same as samples No. 2-1 to No. 2-4, except that the heat treatment temperature was changed. The heat treatment temperature was 450 °C. • Sample No. 2-21 to No. 2-24

[0127] Samples No. 2-21 to No. 2-24 were the same as samples No. 2-1 to No. 2-4, except that the heat treatment temperature was changed. The heat treatment temperature was 500 °C. [Structure and thickness of oxide layer]

[0128] A cross-section of the metal material of each obtained sample was observed using SEM, and the structure was analyzed using EDX in the same manner as in Test Example 1. The results confirmed that all samples contained a base layer with a relatively high aluminum content on the base material side and a composite layer with a relatively high nickel content on the metal layer side. The respective aluminum (Al) and nickel (Ni) contents in the base layer and the composite layer are shown in Table 2. Additionally, it was confirmed that the composite layer contained numerous protrusions projecting from the base layer and a metal region inserted between adjacent protrusions. The base layer and the protrusions were primarily composed of aluminum oxide. The metal region was primarily composed of nickel.Because the composite layer contained a metal component, the nickel content is higher than that of aluminum.

[0129] The thicknesses of the base layer and the composite layer were determined in the same way as in test example 1. The results are shown in Table 2. [Near Adhesion Evaluation 1]

[0130] The close adhesion of each obtained sample after etching and cooling of the metal material was evaluated in the same manner as in test example 1. The results are shown in Table 2. [Near Adhesion Evaluation 2]

[0131] The metal material of each sample was wrapped around a stainless steel holder without heating. Near adhesion evaluation 2 and near adhesion evaluation 1 are identical with respect to the presence or absence of heating of the metal material. The results are shown in Table 2. It should be noted that no heating was performed in near adhesion evaluation 2. Therefore, bendability can be evaluated in near adhesion evaluation 2, but heat resistance cannot. As shown in Table 2, all samples perform excellently in the close-up adhesion evaluation 1 when the average thickness of the oxide layer is not less than 50 nm and not greater than 250 nm. In particular, samples 2-2 to 2-4, 2-12, 2-13, and 2-21 to 2-23, in which the average thickness of the base layer is not less than 50 nm and not greater than 230 nm, and the average thickness of the composite layer is not less than 20 nm and not greater than 220 nm, also perform excellently in the close-up adhesion evaluation 2. Conversely, samples 2-1 and 2-11, in which the average thickness of the base layer is less than 30 nm, perform poorly in the close-up adhesion evaluation 2. It may be considered that this is due to the small average thickness of the base layer reducing the close adhesion between the base material and the oxide layer.Additionally, it is evident that samples No. 2-14 and No. 2-24, in which the.

[0132] When the average thickness of the composite layer is less than 20 nm, the results of the near adhesion evaluation 2 are inferior. It can be considered that this is because the small average thickness of the composite layer reduces the near adhesion between the oxide layer and the metal layer. It can be considered that the near adhesion between the oxide layer and the metal layer has a greater degree of reduction in machinability than the near adhesion between the oxide layer and the base material. Therefore, it can be considered that the result of the near adhesion evaluation 2 was inferior when the average thickness of the composite layer was small compared to when the average thickness of the base layer was small. Additionally, as shown in Table 2, it is evident that the average thickness of the base layer and the average thickness of the composite layer depend on the heat treatment conditions.First, samples are compared that are identical in heat treatment time but differ in heat treatment temperature.

[0133] It is then evident that when the heat treatment temperature is higher, the average thickness of the base layer is greater, and the thickness of the oxide layer is also greater. However, it is evident that when the heat treatment time is long, the thickness of the composite layer decreases as the heat treatment temperature increases. Next, samples with identical heat treatment temperatures but differing heat treatment times are compared. It can then be seen that when the heat treatment time is longer, the average thickness of the base layer is greater, and the thickness of the oxide layer is also greater. However, it is evident that the thickness of the composite layer decreases as the heat treatment time increases.The reason why the average thickness of the composite layer decreases when the heat treatment time and temperature increase can be considered as follows: the hydroxide forming the precursor layer is readily converted to an oxide, and the base layer tends to be thicker. From the above, it is evident that under the conditions within specified ranges, heat treatment readily converts the hydroxide forming the precursor layer and can consequently affect the average thickness of both the base layer and the average thickness of the composite layer within those specific ranges.

[0134] The present invention is not limited to these examples, but is defined by the claims, and it is intended that the present invention includes all modifications within a meaning and scope of protection of the claims. For example, the shape of the base material, the conditions of the nickel plating solution, the heat treatment conditions, and the like can be appropriately modified in the test examples. REFERENCE MARK LIST 1 Metal material 2 Basic material 3 Oxide layer 31 Base layer 32 Composite layer, 321 lead, 322 In-depth study, 323 Metal sector 35 pores 4 metal layers 100 First coating material, 200 Second coating material 110 basic materials, 120 thin film 130 precursor layer 131 Base layer 132 Composite layer, 1321 lead, 1322 In-depth study, 1323 Metal sector 140 metal layer 300 Nickel plating solution L1, L2 line< / wirkungen> < / bereitstellung> < / anwendungen> < / sonstiges> < / metallschicht> < / durchschnittsdicke> < / metallbereich> < / kompositschicht> < / basisschicht> < / metallmaterial>

Claims

[1] Metal material (1), comprising: a basic material (2); an oxide layer (3) arranged on a surface of the base material (2); and a metal layer (4) arranged on a surface of the oxide layer (3), wherein the base material (2) contains aluminium, the oxide layer (3) contains aluminium, nickel and oxygen, the metal layer (4) contains nickel, and the average thickness of the oxide layer (3) is not less than 50 nm and not more than 250 nm, wherein the oxide layer (3) contains a plurality of dispersed pores (35). [2] Metal material (1) according to claim 1, wherein the oxide layer (3) comprises: a base layer (31) arranged on one side of the base material, and a composite layer (32) arranged on a metal layer side, wherein the base layer (31) has a higher aluminum content than that of nickel, and the composite layer (32) has a higher nickel content than that of aluminium. [3] Metal material (1) according to claim 2, wherein the base layer (31) contains not less than 30 atomic % and not more than 60 atomic % of aluminum. [4] Metal material (1) according to claim 2 or 3, wherein the composite layer (32) contains not less than 30 atomic % and not more than 70 atomic % of nickel. [5] Metal material (1) according to any one of claims 2 to 4, wherein an average thickness of the base layer (31) is not less than 30 nm and not greater than 230 nm. [6] Metal material (1) according to any one of claims 2 to 5, wherein an average thickness of the composite layer (32) is not less than 20 nm and not greater than 220 nm. [7] Metal material (1) according to any one of claims 2 to 6, wherein the composite layer (32) comprises: a multitude of projections (321) extending from the base layer (31); and a metal area (323) which is inserted between adjacent projections (321) of the same, wherein Each of the multiple protrusions (321) contains aluminium and oxygen, and the metal area (323) contains nickel. [8] Metal material (1) according to any one of claims 1 to 7, wherein an interface at which the base material (2) and the oxide layer (3) are in contact with each other is formed in a surface condition in which a roughness greater than 1 / 3 of a roughness difference between a projection (321) and a depression (322) in the composite layer (32) is. [9] Metal material (1) according to any one of claims 1 to 8, wherein the size of the pores (35) is not less than 1 nm and not greater than 50 nm. [10] Metal material (1) according to any one of claims 1 to 9, wherein an average thickness of the metal layer (4) is not less than 3 µm and not greater than 15 µm. [11] Metal material (1) according to any one of claims 1 to 10, wherein the base material (2) is a rolled wire, and the diameter of the wire rod is not less than 0.04 mm and not greater than 5 mm. [12] Metal material (1) according to any one of claims 1 to 11, wherein the base material (2) is a rolled wire, and a ratio of the average thickness of the oxide layer (3) to the diameter of the base material (2) is not less than 0.00005 and not greater than 0.0025. [13] Metal material (1) according to any one of claims 1 to 12, wherein the base material (2) is a rolled wire, and a ratio of the average thickness of the metal layer (4) to the diameter of the base material (2) is not less than 0.003 and not greater than 0.

075. [14] Metal material (1) according to claim 2, wherein the base material (2) is made of an aluminum alloy containing a doped element, and the base layer (31) contains the doped element. [15] Metal material (1) according to any one of claims 1 to 14, wherein the oxide layer (3) contains not less than 20 atomic % and not more than 55 atomic % of oxygen. [16] Method for producing a metal material (1), comprising: Providing a base material (110) containing aluminium; Arranging a precursor layer (130) containing aluminium and nickel on a surface of the base material (110); Arranging a metal layer (140) containing nickel on a surface of the precursor layer (130); and Applying a heat treatment to the base material (110) on which the precursor layer (130) and the metal layer (140) are arranged, at a temperature of not less than 400 °C and not more than 600 °C, to transform the precursor layer (130) into an oxide layer (3) containing aluminium, nickel and oxygen, wherein the arrangement of a precursor layer (130) includes: Formation of an aluminum oxide-containing thin film (120) on the surface of the base material (110); and Applying electroless plating to the base material (110) on which the thin film (120) is formed, using a nickel plating solution (300) with a pH higher than 9 and lower than 11 at 25 °C.

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