WO2014133075A1 - Steel-aluminium composite foil - Google Patents

Abstract

This steel-aluminium composite foil is provided with: a core layer provided with a steel layer, and an Al-containing metal layer formed upon the steel layer; and an Al layer stacked upon the Al-containing metal layer of the core layer. When viewed in a cross section having a cutting direction that is parallel with a thickness direction, dispersed Fe-Al alloy particles separated from the steel layer are included in the Al-containing metal layer.

Description

Steel aluminum composite foil

The present invention relates to a steel aluminum composite foil.
This application claims priority on February 28, 2013 based on Japanese Patent Application No. 2013-39706 filed in Japan, the contents of which are incorporated herein by reference.

Compound-based solar cells such as CIGS (Copper-Indium-Gallium-Selenium), CIS (Copper-Indium-Selenium), CdTe (Cadmium-Tellur), etc., thin-film solar cells such as amorphous Si, etc. For a hybrid solar cell or organic EL (Electroluminescence) illumination, a base called a base material is used for the purpose of strongly supporting a CIGS layer, a CIS layer, a CdTe layer, an amorphous Si layer, or an organic EL layer. .

Conventionally, a glass substrate is often used as the substrate as described in Patent Document 1. Since glass is easy to break, it is necessary to increase the thickness to improve the strength. However, when the thickness of the glass is increased, there is a problem that the solar cell and the organic EL lighting itself become heavy.

On the other hand, it has been attempted to use a metal foil that is difficult to break and is suitable for reducing the thickness, as a substrate that can replace the glass substrate. The metal foil as the substrate is required to have good corrosion resistance, surface smoothness, and elastoplastic deformation.

The corrosion resistance of the base material is required to enable the metal foil used as the base material to be exposed to the outdoor environment for a long period of 20 years or longer.

The surface smoothness of the base material is required to prevent the solar cell layer and the organic EL layer laminated on the base material from being physically damaged by the protruding defects present on the base material surface. . The surface of the base material is desirably a smooth surface having no protruding defects.

The elasto-plastic deformability of the base material is required to enable the base material to be wound into a roll shape. If the base material can be wound into a roll shape, the manufacturing process of solar cells and the like is changed from a conventional batch process to a continuous process such as a Roll to Roll process that was impossible with a hard glass base material. It becomes possible to change. As a result, the manufacturing cost of solar cells and organic EL lighting can be greatly reduced.

As a metal foil for a base material, use of a metal foil (referred to as a stainless steel foil) using stainless steel having excellent corrosion resistance is generally in progress. In Patent Document 2, a base material in which an organic film is further formed on a stainless steel foil is used.

Stainless steel foil is used as a metal foil for a substrate because it has excellent corrosion resistance. However, stainless steel foil has a problem of high price because it contains chromium. In addition, the stainless steel foil is not easy to roll because of the high hardness of the stainless steel itself, and has a problem that the manufacturing cost for forming the foil is high. Therefore, the use frequency is low compared with a glass substrate.

On the other hand, metal foil (hereinafter referred to as ordinary steel foil) using ordinary steel (carbon steel) is less expensive than stainless steel and has a high plastic deformability. Significantly lower than stainless steel foil. However, ordinary steel foil itself cannot satisfy the corrosion resistance required as a metal foil for a substrate. With ordinary steel foil that satisfies the above-mentioned corrosion resistance, surface smoothness, and elastoplastic deformation required for metal foil for base materials, production costs for solar cells and organic EL lighting are expected to be significantly reduced. it can.

As a normal steel foil with improved corrosion resistance, a normal steel foil provided with an Al-containing metal layer such as an aluminum plating layer has been studied. However, the conventional steel foil having a conventional Al-containing metal layer has insufficient surface smoothness.

Moreover, in the manufacturing process of a solar cell or organic EL lighting, in order to perform heat treatment for various purposes, the metal foil for a substrate after a laminated film such as a CIGS layer or an organic EL layer is formed is about several hundred degrees Celsius. May be cooled after being heated. However, for example, in a normal steel foil having the Al-containing metal layer, the aluminum plating layer may be peeled or cracked when such heat treatment is performed.

Japanese Unexamined Patent Publication No. 2006-80370 Japanese Unexamined Patent Publication No. 2006-295035

The present invention has been made in view of the above circumstances, and simultaneously satisfies the corrosion resistance, surface smoothness, and elastoplastic deformability required as a metal foil for a substrate for solar cells and organic EL lighting, and is heated to a high temperature. It is an object of the present invention to provide a steel / aluminum composite foil in which peeling or cracking of an Al-containing metal layer or the like hardly occurs even when cooled.

The gist of the present invention is as follows.
(1) A steel aluminum composite foil according to an aspect of the present invention is laminated on a steel layer and a core layer having an Al-containing metal layer formed on the steel layer, and the Al-containing metal layer of the core layer. An Al layer, and when viewed in a cross section in which the thickness direction and the cutting direction are parallel, the Al-containing metal layer includes Fe-Al alloy particles dispersed away from the steel layer. It is.
(2) In the steel / aluminum composite foil according to (1), the Fe—Al alloy particles dispersed and separated from the steel layer included in the Al-containing metal layer when viewed in the cross section. The area fraction may be in the range of 7.5 area% or more and less than 50 area% with respect to the Fe—Al alloy grains contained in the cross section.
(3) In the steel / aluminum composite foil according to the above (1) or (2), the particle diameter of the Fe—Al alloy particles dispersed and separated from the steel layer contained in the Al-containing metal layer is: It may be in the range of 0.1 to 5 μm.
(4) In the steel aluminum composite foil according to any one of the above (1) to (3), when viewed in the cross section, the Fe aluminum dispersed and separated from the steel layer in the Al layer. -Al alloy grains may be included.
(5) In the steel / aluminum composite foil according to (4), the area of the Fe—Al alloy grains dispersed and separated from the steel layer contained in the Al layer when viewed in the cross section. The rate may be in the range of 7.5 area% or more and less than 40 area% with respect to the Fe—Al alloy grains contained in the cross section.
(6) In the steel / aluminum composite foil according to the above (4) or (5), the Fe—Al alloy particles dispersed and separated from the steel layer contained in the Al layer have a particle size of 0. 0. It may be in the range of 1-5 μm.
(7) In the steel aluminum composite foil according to any one of the above (1) to (6), when the two outer surfaces of the steel layer having the thickness direction as a normal line are steel layer surfaces, the Al A contained metal layer may be disposed on each of the steel layer surfaces.
(8) In the steel / aluminum composite foil according to (7), when the two outer surfaces of the Al-containing metal layer whose normal direction is the thickness direction are Al-containing metal layer surfaces, the Al layer is You may distribute | arrange on the said Al containing metal layer surface.
(9) In the steel / aluminum composite foil according to any one of (1) to (8), a void included in the cross section may have an equivalent circle diameter of less than 1 μm.
(10) In the steel aluminum composite foil according to any one of the above (1) to (9), the chemical component of the Al-containing metal layer contains 1 to 15% by mass of Si, and the balance is Al and It may consist of impurities.
(11) In the steel aluminum composite foil according to any one of (1) to (10), the Fe—Al alloy particles are selected from at least FeAl ₃ , Fe ₂ Al ₈ Si, and FeAl ₅ Si. One intermetallic compound may be included.
(12) In the steel / aluminum composite foil according to any one of (1) to (11), the chemical component of the Al layer may be composed of 99.0% by mass or more of Al and impurities.
(13) In the steel aluminum composite foil according to any one of (1) to (12), the surface roughness Ra of the surface of the Al layer may be 10 to 25 nm.
(14) In the steel / aluminum composite foil according to any one of (1) to (13), the surface of the Al layer further includes at least one selected from an AlN layer and an Al ₂ O ₃ layer. May be.
(15) In the steel aluminum composite foil according to any one of (1) to (13), the surface of the Al layer may further include at least one selected from a sol-gel layer and a laminate layer. Good.

According to the said aspect of this invention, while satisfy | filling simultaneously the corrosion resistance, surface smoothness, and elastic-plastic deformability which are requested | required as a metal foil for base materials of a solar cell or organic electroluminescent illumination, it heated and cooled to high temperature Even in such a case, it is possible to provide a steel / aluminum composite foil in which peeling or cracking of an Al-containing metal layer or the like hardly occurs.

It is an expanded section schematic diagram showing the important section of the steel aluminum composite foil concerning one embodiment of the present invention. It is a cross-sectional schematic diagram which shows the principal part of the modification of the steel aluminum composite foil which concerns on this embodiment. FIG. 3 is an enlarged schematic cross-sectional view showing Fe—Al alloy grains and their vicinity included in the steel aluminum composite foil according to the present embodiment. It is a cross-sectional schematic diagram which shows the principal part of the modification of the steel aluminum composite foil which concerns on this embodiment. It is a cross-sectional schematic diagram of the steel aluminum composite foil which concerns on this embodiment.

As a metal foil for a substrate used for solar cells or organic EL lighting, an aluminum-plated steel foil can be cited as a candidate in addition to an aluminum foil and a stainless steel foil. This aluminum plated steel foil is a metal foil in which an aluminum plated layer that is an Al-containing metal layer is disposed on a steel plate that is plain steel. Aluminum plated steel foil is more promising as a metal foil for a substrate than aluminum foil and stainless steel foil because it is excellent in strength and cost such as raw material costs and manufacturing costs. However, in order to use the aluminum-plated steel foil as a base material, it is necessary to further improve the surface smoothness and further suppress peeling and cracking.

Generally, an aluminum-plated steel foil is manufactured by rolling an aluminum-plated steel sheet into a foil shape. Moreover, generally the said aluminum plating steel plate before rolling is manufactured by immersing the steel plate which is plain steel in a hot dipping aluminum plating bath. This molten aluminum plating bath may contain Si for the purpose of lowering the melting temperature. In this case, a eutectic structure of an Al phase and a Si phase is generated in the aluminum plating layer. In addition, by performing hot-dip aluminum plating, an Fe—Al alloy layer is also formed at the interface (boundary) between the aluminum plating layer and the steel layer (base metal).

When using an aluminum plated steel foil as a substrate, a power generation layer of a solar cell or an organic EL element is formed on the aluminum plated layer of the aluminum plated steel foil. Therefore, high flatness (surface smoothness) is required for the surface of the aluminum plating layer. However, when the above eutectic structure of the Al phase and the Si phase is present in the aluminum plating layer, the surface of the aluminum plating layer is likely to be uneven due to the interface between the Al phase and the Si phase. That is, it can be said that there is a limit in improving the surface smoothness of an aluminum plating layer containing an alloy component such as Si.

Also, the manufacturing process of solar cells and organic EL lighting includes a process of heating the substrate to a relatively high temperature and then cooling it. When the aluminum plated steel foil receives such a heat history, the steel layer and the aluminum plated layer may be peeled off, and cracks may occur in the aluminum plated layer. The occurrence of such peeling and cracking is due to the large difference between the thermal expansion coefficient of the steel layer and the aluminum plating layer, and the presence of an Fe-Al alloy layer at the interface between the steel layer and the aluminum plating layer. Due to such things.

Thus, in order to use an aluminum-plated steel foil as a base material, it is necessary to improve surface smoothness and prevent peeling and cracking of the aluminum plating layer.

In response to these problems, as a method for improving the surface smoothness of the aluminum-plated steel foil, it has been studied to laminate a pure aluminum material on the aluminum-plated steel sheet by clad rolling. Since the pure aluminum material does not have a eutectic structure and is an Al phase single phase, the steel aluminum composite foil obtained by clad rolling satisfies the surface smoothness required as a base material. However, this steel aluminum composite foil still has problems such as peeling between the aluminum plating layer and the steel layer and cracking of the aluminum plating layer.

The present inventors diligently studied whether or not peeling of the aluminum plating layer and the steel layer and cracking of the aluminum plating layer can be prevented by modifying the aluminum plating layer which is an Al-containing metal layer. As a result, the steel aluminum composite foil described below was found.

Hereinafter, a steel aluminum composite foil according to an embodiment of the present invention will be described in detail.

The steel aluminum composite foil 1 according to the present embodiment is configured by laminating an Al layer 3 on a core layer 2 as shown in FIG. The core layer 2 is composed of a steel layer 4 and an Al-containing metal layer 5 formed on the steel layer 4. FIG. 1 shows a steel / aluminum composite foil 1 when viewed in a cross section in which the thickness direction and the cutting direction are parallel, and a part of the core layer 2 and Al laminated on the core layer 2 are shown. Layer 3 is shown enlarged.

The steel layer 4 constituting the core layer 2 has a thickness of about 5 to 200 μm and is preferably plain steel (carbon steel). If thickness is this range, sufficient intensity | strength and the outstanding elastic-plastic deformability can be maintained. If thickness is 200 micrometers or less, the mass of the steel aluminum composite foil 1 will not become excessively heavy. If the thickness is 5 μm or more, sufficient strength can be obtained. A more preferable range of the thickness of the steel layer 4 is 10 to 160 μm.

The Al-containing metal layer 5 constituting the core layer 2 is formed by Al-containing plating, and more specifically, is formed by hot-dip aluminum plating. By forming this Al-containing metal layer 5 on the steel layer 4, the corrosion resistance of the steel layer 4 can be enhanced. The chemical component of the Al-containing metal layer 5 preferably contains 1 to 15% by mass of Si on the average, and the balance is made of Al and impurities. The “impurities” in the present embodiment refer to those mixed from raw materials or the manufacturing environment. Moreover, the chemical component as an average means an average value when a plurality of measurements are performed at a plurality of locations.

By containing Si in the molten aluminum plating bath, the melting point of the molten aluminum plating bath can be preferably reduced. As a result, the hot dipping operation can be facilitated. Furthermore, by containing Si in the molten aluminum plating bath, excessive growth of the hard Fe—Al alloy layer generated at the interface 6 between the steel layer 4 and the Al-containing metal layer 5 can be preferably suppressed. If the Si content is 15% by mass or less, coarse Si does not precipitate in the Al-containing metal layer 5, and there is no possibility of impairing corrosion resistance and plating adhesion. Further, if the Si content is low, the entire Al of the Al-containing metal layer 5 may be alloyed with Fe of the steel layer 4 (ground iron), so the Si content is preferably 1% by mass or more. The mass% or more is more preferable.

The thickness of the Al-containing metal layer 5 is preferably in the range of 0.3 to 25 μm, more preferably in the range of 1 to 25 μm, still more preferably in the range of 3 to 25 μm, and most preferably in the range of 8 to 25 μm. If thickness is 0.3 micrometer or more, a suitable corrosion-resistant effect will be acquired. Further, if the thickness is 25 μm or less, it is not necessary to plate a large amount of Al, and the production cost can be improved.

As shown in FIG. 1, Fe—Al alloy grains 7 are dispersedly formed at the interface 6 between the steel layer 4 and the Al-containing metal layer 5. When hot-dip aluminum plating is performed, an Fe—Al alloy phase is formed in layers at the interface 6 between the steel layer 4 and the Al-containing metal layer 5. The Fe—Al alloy grains 7 are formed by dispersing this Fe—Al alloy layer. The Fe—Al alloy grain 7 preferably contains at least one intermetallic compound selected from, for example, FeAl ₃ , Fe ₂ Al ₈ Si, and FeAl ₅ Si. Since the Fe—Al alloy layer is very hard and brittle, if it remains in a layered state, it cannot follow the deformation when the steel-aluminum composite foil 1 is elastically plastically deformed, and the steel layer 4 and the Al-containing metal layer 5 are peeled off. And the crack of the Al-containing metal layer 5 is induced. However, in the steel / aluminum composite foil 1 of the present embodiment, the Fe—Al alloy grains 7 are dispersed, so that the steel layer 4 and the Al-containing metal layer 5 are formed when the steel / aluminum composite foil 1 is elastically plastically deformed. And peeling of the Al-containing metal layer 5 can be prevented.

The Fe—Al alloy layer formed at the interface 6 between the steel layer 4 and the Al-containing metal layer 5 has an average chemical composition of Fe: 10 to 35 atomic%, Al: 50 to 80 atomic%, Si: 0 It is preferable that the total amount of Fe, Al, and Si is 95 atomic% or more. The chemical components of the Fe—Al alloy grains 7 formed from this Fe—Al alloy layer are, on average, Fe: 10 to 35 atomic%, Al: 50 to 80 atomic%, Si: 0.5 to 20 atomic%, And it is preferable that the sum total of Fe, Al, and Si becomes 95 atomic% or more. However, the Fe—Al alloy grains 7 may have different chemical components for each grain. The chemical components of the Fe—Al alloy grains 7 are more preferably, on average, Fe: 15 to 25 atomic%, Al: 60 to 75 atomic%, and Si: 1 to 15 atomic%.

The Fe—Al alloy grains 7 are in contact with the steel layer 4 and dispersed in the interface 6 between the steel layer 4 and the Al-containing metal layer 5, while being separated from the steel layer 4. Fe—Al alloy grains 7b dispersed in the Al-containing metal layer 5 are included. Among these, the presence of the Fe—Al alloy particles 7 b dispersed in the Al-containing metal layer 5 in a state of being separated from the steel layer 4 can improve the elastoplastic deformability.

Here, the thermal expansion coefficient of the steel layer 4 (for example, 10.5 to 12.2 × 10 ⁻⁶ / K) and the thermal expansion coefficient of Al forming the Al-containing metal layer 5 (for example, 22.3 × 10 ⁻⁶ / K). The difference from K) is large. However, since the Fe—Al alloy grains 7 are separated from the steel layer 4 and dispersed in the Al-containing metal layer 5, a thermal expansion pinning effect on the Al-containing metal layer 5 is exhibited. As a result, even if the steel-aluminum composite foil 1 of the present embodiment is subjected to a heat history that is heated to several hundred degrees Celsius during manufacturing processes such as solar cells and organic EL lighting, and then cooled to near room temperature, the steel layer 4 and the Al-containing metal layer 5 are prevented from peeling off and the Al-containing metal layer 5 is prevented from cracking. This effect is that the thermal expansion coefficient of the Al-containing metal layer 5 is apparently lowered by the Fe—Al alloy grains 7b, and the difference between the thermal expansion coefficient of the steel layer 4 and the thermal expansion coefficient of the Al-containing metal layer 5 is small. It is presumed to be caused by In order to disperse the Fe—Al alloy grains 7b in the Al-containing metal layer 5, the cold rolling conditions after clad rolling may be controlled.

When viewed in a cross section in which the thickness direction and the cutting direction are parallel, the area fraction of the Fe—Al alloy particles 7b dispersed and separated from the steel layer 4 contained in the Al-containing metal layer 5 is the above cross section. A range of 7.5 area% or more and less than 50 area% is preferable with respect to the Fe—Al alloy grains 7 contained therein. The lower limit of the area fraction of the Fe—Al alloy grains 7b is more preferably 10 area%, and further preferably 15 area%. Further, the upper limit of the area fraction of the Fe—Al alloy particles 7b is more preferably 40 area%, and further preferably 35 area%. If the area fraction of the Fe—Al alloy grains 7b is 7.5 area% or more, peeling between the steel layer 4 and the Al-containing metal layer 5 and cracking of the Al-containing metal layer 5 can be effectively prevented. The area fraction of the Fe—Al alloy grain 7b is preferably as large as possible, but it is difficult to make it 50 area% or more due to restrictions on the manufacturing process, so the upper limit is less than 50 area%. Whether the Fe—Al alloy particles 7 are separated from the steel layer 4 may be determined by observing the cross section of the steel layer 4 and the Al-containing metal layer 5.

The particle diameter of the Fe—Al alloy particles 7b dispersed away from the steel layer 4 contained in the Al-containing metal layer 5 is preferably in the range of 0.1 to 5 μm. The lower limit of the particle size of the Fe—Al alloy particles 7b is more preferably 0.2 μm. Further, the upper limit of the particle diameter of the Fe—Al alloy particles 7b is more preferably 4 μm, and further preferably 3 μm. If the particle diameter of the Fe—Al alloy particles 7b exceeds 5 μm, the Al-containing metal layer 5 may crack when the steel / aluminum composite foil 1 is deformed. Further, when the particle diameter of the Fe—Al alloy particles 7b is less than 0.1 μm, even if the Fe—Al alloy particles 7b are dispersed in the Al-containing metal layer 5, the pinning effect of thermal expansion is not sufficiently exhibited. There is a fear.

The interface 6 between the steel layer 4 and the Al-containing metal layer 5 is preferably not a flat surface but an uneven surface. The uneven interface 6 is formed when the Fe—Al alloy layer 7 is dispersed as Fe—Al alloy grains 7 by cold rolling after clad rolling, so that the Fe—Al alloy grains 7 become the steel layer 4 and the Al-containing metal layer. It is estimated that it is formed by biting into 5 respectively. Thus, when the interface 6 between the steel layer 4 and the Al-containing metal layer 5 is an uneven surface, the anchor effect is exhibited when the steel layer 4 and the Al-containing metal layer 5 are thermally expanded at a high temperature, The peeling between the steel layer 4 and the Al-containing metal layer 5 can be prevented more effectively.

The Al layer 3 is laminated on the Al-containing metal layer 5 of the core layer 2. The Al layer 3 is formed by clad rolling a core material (aluminum-plated steel plate) and an Al material, and further cold rolling. The thickness of the Al layer 3 is preferably in the range of 1 to 140 μm. The lower limit of the thickness of the Al layer 3 is more preferably 3 μm and even more preferably 5 μm. The upper limit of the thickness of the Al layer 3 is more preferably 50 μm and even more preferably 30 μm. If the thickness of the Al layer 3 is 1 μm or more, it becomes a preferable thickness for flattening the surface 3 a of the Al layer 3. Moreover, if this thickness is 140 micrometers or less, since the mass of the Al layer 3 does not increase and the weight reduction of the steel aluminum composite foil 1 is achieved, it is preferable.

The Al layer 3 preferably has an average chemical composition of 99.0% by mass or more of Al and impurities. The Al layer 3 more preferably contains 99.9% by mass or more of Al. Thereby, a eutectic structure is not generated in the Al layer 3, and the surface smoothness of the surface 3a of the Al layer 3 can be preferably increased.

The surface 3a of the Al layer 3 has acceptable surface smoothness when the surface roughness Ra is 600 nm or less, but the surface roughness Ra of the surface 3a of the Al layer 3 is preferably in the range of 10 to 25 nm. A range of ˜20 nm is more preferable. If the surface roughness Ra of the Al layer 3 is 25 nm or less, the surface smoothness required as a substrate for solar cells and organic EL lighting can be preferably satisfied. The smaller the surface roughness Ra of the Al layer 3 is, the better. However, when the surface roughness Ra is less than 10 nm, the cost of the planarization process increases. The surface roughness Ra of the Al layer 3 is controlled in the cold rolling process after clad rolling.

FIG. 2 is an enlarged schematic cross-sectional view showing a main part of a modified example of the steel aluminum composite foil 1 according to the present embodiment. 2 shows a steel / aluminum composite foil 1 when viewed in a cross section in which the thickness direction and the cutting direction are parallel, as in FIG. 1, and a part of the core layer 2 and the core layer are shown. 2 shows an enlarged view of the Al layer 3 stacked on the substrate 2. As shown in FIG. 2, in the steel / aluminum composite foil 1 according to this embodiment, the Al—layer 3 may include Fe—Al alloy grains 7 c dispersed away from the steel layer 4.

When Fe—Al alloy particles 7c dispersed away from the steel layer 4 are contained in the Al layer 3, the pinning effect of thermal expansion on the Al layer 3 is preferably exhibited. As a result, even if the steel-aluminum composite foil 1 is subjected to a heat history that is heated to several hundred degrees Celsius and then cooled to near room temperature, peeling between the Al layer 3 and the Al-containing metal layer 5, the Al-containing metal layer 5 And peeling of the steel layer 4, cracking of the Al layer 3, and cracking of the Al-containing metal layer 5 are preferably prevented. This effect is that the thermal expansion coefficient of the Al layer 3 is apparently lowered by the Fe—Al alloy grains 7c, the difference between the thermal expansion coefficient of the steel layer 4 and the thermal expansion coefficient of the Al layer 3, and the Al-containing metal layer. It is presumed that the difference between the thermal expansion coefficient of 5 and the thermal expansion coefficient of the Al layer 3 is reduced. In order to disperse the Fe—Al alloy grains 7 c in the Al layer 3, the thickness of the Al-containing metal layer 5 is smaller than a value obtained by doubling the maximum value of the grain size range of the Fe—Al alloy grains 7. Thus, it is only necessary to control the coating amount of the steel sheet as the material (the thickness of the Al-containing metal layer 5) and the thickness of the Fe—Al alloy layer. In this way, a part of the Fe—Al alloy particles 7 dispersed away from the steel layer 4 is further dispersed into the Al layer 3 through the Al-containing metal layer 5 in the cold rolling process.

When viewed in a cross section in which the thickness direction and the cutting direction are parallel, the area fraction of the Fe—Al alloy particles 7c dispersed away from the steel layer 4 included in the Al layer 3 is A range of 7.5 area% or more and less than 40 area% with respect to the Fe—Al alloy grains 7 contained is preferable. The lower limit of the area fraction of the Fe—Al alloy grains 7c is more preferably 10 area%, and further preferably 15 area%. Further, the upper limit of the area fraction of the Fe—Al alloy particles 7c is more preferably 30 area%, further preferably 25 area%. If the area fraction of the Fe—Al alloy grain 7c is 7.5 area% or more, peeling between the Al layer 3 and the Al-containing metal layer 5, peeling between the Al-containing metal layer 5 and the steel layer 4, and Al layer 3 And cracking of the Al-containing metal layer 5 can be preferably prevented. The area fraction of the Fe—Al alloy grain 7c is preferably as large as possible, but it is difficult to make it 40% by area or more because of restrictions on the manufacturing process.

The particle diameter of the Fe—Al alloy particles 7c dispersed away from the steel layer 4 included in the Al layer 3 is preferably in the range of 0.1 to 5 μm. The lower limit of the particle size of the Fe—Al alloy particles 7c is more preferably 0.2 μm, and still more preferably 0.3 μm. Further, the upper limit of the particle diameter of the Fe—Al alloy particles 7c is more preferably 4 μm, and further preferably 3.5 μm. If the particle diameter of the Fe—Al alloy particles 7c exceeds 5 μm, the Al layer 3 or the Al-containing metal layer 5 may break when the steel / aluminum composite foil 1 is deformed. Further, if the particle diameter of the Fe—Al alloy particles 7c is less than 0.1 μm, even if the Fe—Al alloy particles 7c are dispersed in the Al layer 3, the pinning effect of thermal expansion may not be sufficiently exhibited. is there. Note that the grain size of the Fe—Al alloy grains 7 c is always smaller than the thickness of the Al layer 3.

FIG. 3 is an enlarged schematic cross-sectional view showing Fe—Al alloy grains 7 included in the steel aluminum composite foil 1 according to the present embodiment and the vicinity thereof. FIG. 3 shows the steel / aluminum composite foil 1 when viewed in a cross section in which the thickness direction and the cutting direction are parallel, as in FIGS. 1 and 2. As shown in FIG. 3, the steel aluminum composite foil 1 according to the present embodiment may include voids 9.

When the void 9 is subjected to a thermal history in which the steel aluminum composite foil 1 is heated to several hundred degrees Celsius and then cooled to near room temperature, the steel layer 4 and the Al-containing metal layer 5 are peeled off, and the Al-containing metal layer. 5 and the Al layer 3 may be peeled off, the Al-containing metal layer 5 may be cracked, or the Al layer 3 may be cracked. Therefore, the electrical resistance of the steel / aluminum composite foil 1 is increased, the photoelectric conversion efficiency is lowered, and the temperature cycle resistance may be lowered. Therefore, it is preferable that the size of the void 9 is small. Specifically, when viewed in a cross section in which the thickness direction and the cutting direction are parallel, it is preferable that the void 9 included in the cross section has an equivalent circle diameter (equivalent circle diameter) of less than 1 μm. If the equivalent circle diameter of the void 9 is less than 1 μm, peeling between the steel layer 4 and the Al-containing metal layer 5, peeling between the Al-containing metal layer 5 and the Al layer 3, cracking of the Al-containing metal layer 5, or Al layer 3 is less likely to cause cracking. In order to control the equivalent circle diameter of the void 9, the total thickness of the aluminum plating layer (Al-containing metal layer) and the Al material before the clad rolling process, and the total reduction ratio in the clad rolling and cold rolling Can be controlled.

FIG. 4 is an enlarged schematic cross-sectional view showing a main part of a modified example of the steel aluminum composite foil 1 according to the present embodiment. As shown in FIG. 4, various coating layers 8 may be formed on the Al layer 3 of the steel aluminum composite foil 1 of the present embodiment. Further, the coating layer 8 has acceptable surface smoothness when the surface roughness Ra is 600 nm or less, but the surface roughness Ra of these coating layers 8 is Al in the case where these coating layers 8 are not formed. Similar to the surface 3a of the layer 3, the range of 10 to 25 nm is preferable, and the range of 10 to 20 nm is more preferable.

For example, an AlN layer having a thickness of 0.01 to 4 μm or an Al ₂ O ₃ layer having a thickness of 0.05 to 50 μm is preferably formed on the Al layer 3 as the covering layer 8. When the thickness of the AlN layer is 0.01 μm or more, or the thickness of the Al ₂ O ₃ layer is 0.05 μm or more, the surface of the Al layer 3 can be made insulative, and insulation of solar cells and organic EL lighting It is preferable because it can function as a conductive underlayer. Generating an AlN layer with a thickness of more than 4 μm or an Al ₂ O ₃ layer with a thickness of more than 50 μm is not preferable because production costs increase.

Further, instead of the AlN layer or the Al ₂ O ₃ layer, a sol-gel layer having a thickness of 0.001 to 8 μm may be formed on the Al layer 3. The sol-gel layer is an sol-gel layer having an inorganic skeleton having a siloxane bond developed in a three-dimensional network structure as a main skeleton, and at least one of bridging oxygens of the skeleton is substituted with an organic group and / or a hydrogen atom. . By having the sol-gel layer, the same effect as the AlN layer and the Al ₂ O ₃ layer can be obtained. More preferably, when the thickness is 0.1 μm or more, the above-described effect may be further increased. When the thickness of the sol-gel layer is less than 0.001 μm, the above effect cannot be obtained. If the thickness exceeds 8 μm, the production cost increases.

Further, instead of the AlN layer or the Al ₂ O ₃ layer, a laminate layer having a thickness of 1 to 50 μm may be formed on the Al layer 3. Examples of the laminate layer include a laminate layer made of a plastic film selected from polyolefin, polyester, polyamide, and polyimide. By having a laminate layer, it is possible to obtain the same effect as the AlN layer and _{the Al} 2 _{O 3} layer. If the thickness of the laminate layer is less than 1 μm, the above effect cannot be obtained. If the thickness exceeds 50 μm, the production cost increases.

With the above structure, for example, with a module circuit in which CIGS solar cells are connected in series, a withstand voltage of 500 V or more can be secured, and dielectric breakdown can be avoided. Even if dielectric breakdown does not occur, the presence of leakage current causes a decrease in photoelectric conversion efficiency of the solar cell module, but such leakage can be prevented by adopting the above structure.

Moreover, as a photoelectric converting layer formed on the steel aluminum composite foil 1 of this embodiment, compound type solar cells, such as CIGS, CIS, and CdTe, thin film type solar cells, such as amorphous Si, and the hybrid which laminated | stacked two or more layers thereof Type solar cells can be used. An organic EL lighting circuit can also be formed on the steel aluminum composite foil 1. In particular, the main components of the above-described CIGS and CIS are not particularly limited, and are preferably at least one compound semiconductor having a chalcopyrite structure. The main components of the photoelectric conversion layer are the group Ib element and the group IIIb element. It is preferably at least one compound semiconductor containing a VIb group element. Furthermore, since the light absorptance is high and high photoelectric conversion efficiency is obtained, the main component of the photoelectric conversion layer is at least one kind of Ib group element selected from Cu and Ag, Al, Ga, In, and the like. It is preferable that the semiconductor is at least one compound semiconductor containing at least one group IIIb element selected from more and at least one group VIb element selected from S, Se, Te and the like. Specifically, examples of the compound semiconductor include CuAlS ₂ , CuGaS ₂ , CuInS ₂ , CuAlSe ₂ , CuGaSe ₂ , CuInSe ₂ (CIS), AgAlS ₂ , AgGaS ₂ , AgInS ₂ , AgAlSe ₂ , AgGaSe ₂ , AgInSe ₂ , AgAlTe ₂ , AgGaTe ₂ , AgInTe ₂ , Cu (In _1-x Ga _x ) Se ₂ (CIGS), Cu (In _1-x Al _x ) Se ₂ , Cu (In _1-x Ga _x ) (S, Se) _{2, Ag (In 1-x} Ga x) Se 2 and _{Ag (In 1-x Ga x} ) (S, Se) 2 or the like can be used.

The steel / aluminum composite foil 1 according to the present embodiment only needs to have the Al-containing metal layer 5 and the Al layer 3 on one foil surface on the side where the power generation layer and the organic EL element of the solar cell are formed. However, the steel-aluminum composite foil 1 according to the present embodiment is also provided with an Al-containing metal on the other foil surface, which is the foil surface opposite to the one foil surface on the side where the power generation layer and the organic EL element of the solar cell are formed. It may have a layer 5. Alternatively, the steel / aluminum composite foil 1 according to the present embodiment is provided with an Al-containing metal also on the other foil surface, which is the opposite foil surface to the one on which the power generation layer and the organic EL element of the solar cell are formed. The layer 5 and the Al layer 3 may be included.

FIG. 5 is a schematic cross-sectional view of the steel / aluminum composite foil according to the present embodiment. The steel / aluminum composite foil 1 according to the present embodiment is one foil on the side on which a power generation layer or an organic EL element of a solar cell is formed. The case where the Al-containing metal layer 5 and the Al layer 3 are provided on the surface and the other foil surface is illustrated. As shown in FIG. 5, when viewed in a cross section in which the thickness direction and the cutting direction are parallel, the two outer surfaces of the steel layer 4 having the thickness direction as the normal line are the steel layer surfaces 4a (the steel layer surface 4a is the interface 6). The Al-containing metal layer 5 is preferably disposed on each steel layer surface 4a. And when it sees in the said cross section, when the two outer surfaces of the Al containing metal layer 5 which make a thickness direction a normal line are made into the Al containing metal layer surface 5a, the Al layer 3 is on each Al containing metal layer surface 5a. It is preferable to be arranged in In FIG. 5, illustration of Fe—Al alloy grains 7 (7a, 7b, 7c), voids 9, various coating layers 8 and the like is omitted.

For example, when the steel-aluminum composite foil 1 having the Al-containing metal layer 5 and the Al layer 3 only on one foil surface is wound in a roll shape, it is wound in a roll shape when manufacturing a solar cell or organic EL lighting. It may be necessary to reverse the winding direction of the steel aluminum composite foil 1 being taken. On the other hand, in the steel aluminum composite foil 1 having the Al-containing metal layer 5 and the Al layer 3 on one foil surface and the Al-containing metal layer 5 and the Al layer 3 on the other foil surface, In addition, the solar cell power generation layer and the organic EL element can be formed on either foil surface during manufacturing of organic EL lighting or the like, so that the operability is excellent.

In addition, in the steel aluminum composite foil 1 having the Al-containing metal layer 5 and the Al layer 3 only on one foil surface, the difference in plastic deformability and mechanical properties between the steel layer 4 and the Al-containing metal layer 5, Due to differences in plastic deformability and mechanical properties between the steel layer 4 and the Al layer 3, and differences in plastic deformability and mechanical properties between the Al-containing metal layer 5 and the Al layer 3, the cladding After cold rolling following rolling, warp may occur in the steel aluminum composite foil 1. When warpage occurs in the steel / aluminum composite foil 1, it may be difficult to form a power generation layer or an organic EL element of a solar cell on the steel / aluminum composite foil 1. On the other hand, the steel aluminum composite foil 1 having the Al-containing metal layer 5 on the other foil surface, which is the opposite foil surface to the one on which the power generation layer and the organic EL element of the solar cell are formed. Then, after the cold rolling following the clad rolling, the steel aluminum composite foil 1 is less likely to warp, which is preferable. Also, a steel / aluminum composite foil having an Al-containing metal layer 5 and an Al layer 3 on the other foil surface, which is the opposite foil surface to the one on which the power generation layer and organic EL element of the solar cell are formed. No. 1 is preferable because warp is less likely to occur in the steel-aluminum composite foil 1 after cold rolling following clad rolling.

In addition, when manufacturing an aluminum plating steel plate by immersing a steel plate in a molten aluminum plating bath, when it sees in the cross section in which the thickness direction and a cutting direction are parallel, it extends over the perimeter of the outline of the steel layer 4. An Al-containing metal layer 5 is formed. In this case, the Al layer 3 may be laminated only on one Al-containing metal layer surface 5 a of the two Al-containing metal layer surfaces 5 a of the Al-containing metal layer 5, or the two Al-containing metal layers 5 may contain two Al The Al layer 3 may be laminated on the metal layer surface 5a. On the other hand, the side edge of the aluminum-plated steel plate in which the Al-containing metal layer 5 is formed over the entire circumference of the contour line of the steel layer 4 (the end in the plate width direction of the steel plate and the portion along the longitudinal direction of the steel plate) May be cut off. In the aluminum-plated steel sheet whose side edge is cut, Al is contained only on the two steel layer surfaces 4a of the steel layer 4 having the thickness direction as a normal when viewed in a cross section in which the thickness direction and the cutting direction are parallel. A metal layer 5 is disposed. In this case, the Al layer 3 may be laminated only on one Al-containing metal layer surface 5 a of the two Al-containing metal layer surfaces 5 a of the Al-containing metal layer 5, or the two Al-containing metal layers 5 may contain two Al The Al layer 3 may be laminated on the metal layer surface 5a. That is, in the steel / aluminum composite foil 1 according to the present embodiment, the Al-containing metal layer 5 may be arranged over the entire circumference of the contour line of the steel layer 4, and on the two steel layer surfaces 4 a of the steel layer 4. May be arranged only. And in the steel aluminum composite foil 1 which concerns on this embodiment, the Al layer 3 is laminated | stacked only on one Al containing metal layer surface 5a of the two Al containing metal layer surfaces 5a of the Al containing metal layer 5 as needed. Alternatively, the Al layer 3 may be laminated on the two Al-containing metal layer surfaces 5 a of the Al-containing metal layer 5. In addition, when manufacturing an aluminum plating steel plate with a curtain coater etc., when it sees in the cross section in which the thickness direction and a cutting direction are parallel, among the two steel layer surfaces 4a of the steel layer 4 which makes a thickness direction a normal line The Al-containing metal layer 5 is disposed only on one steel layer surface 4a. In this case, the Al layer 3 may be laminated on the formed Al-containing metal layer 5.

As described above, the thickness of the steel layer 4, the thickness of the Al-containing metal layer 5, the chemical component of the Al-containing metal layer 5, the thickness of the Al layer 3, the chemical component of the Al layer 3, the surface roughness Ra of the Al layer 3 , Fe—Al alloy grain 7 (7a, 7b, 7c) grain size, Fe—Al alloy grain 7 (7a, 7b, 7c) area fraction, Fe—Al alloy grain 7 (7a, 7b, 7c) The method of measuring the constituent phases and the equivalent circle diameter of the void 9 may be by observing a cut surface obtained by plane cutting along the thickness direction so that the plate width direction orthogonal to the rolling direction becomes the observation surface. In addition, it is preferable to average each measured value measured from several observation visual fields in several cut surfaces.

The average thickness, particle size, area fraction, surface roughness Ra, etc. can be determined by image analysis of the metal structure of the cut surface. The image analysis is preferably performed at a magnification such that the observation visual field is within 200 μm in the plate width direction, and at least 15 visual fields are analyzed so that the total visual field in the plate width direction is 3000 μm or more. Further, the equivalent-circle diameter of each Fe—Al alloy grain 7 (7a, 7b, 7c) observed within the analysis field of view was measured as the grain size, and the grain size range was examined. In addition, when the Fe—Al alloy particles 7 separated from the steel layer 4 are present at a position extending over both the Al-containing metal layer 5 and the Al layer 3, the portion contained in the Al-containing metal layer 5 is removed from the Fe—Al alloy particles 7b. The area fraction and the equivalent circle diameter (particle diameter) were calculated with the portion contained in the Al layer 3 as the Fe—Al alloy grain 7c. In addition, you may measure said surface roughness Ra using a surface roughness measuring machine.

Also, the circle-equivalent diameter of the void 9 can be obtained by image analysis of the metal structure of the cut surface. The image analysis is preferably performed at a magnification such that the observation visual field is within 200 μm in the plate width direction, and a plurality of visual fields are analyzed so that the total visual field in the plate width direction is 3000 μm or more.

In addition, by using EPMA (Electron Probe Micro Analysis, Electron Probe Micro Analysis), EDX (Energy Dispersive X-ray Analysis, Energy Dispersive X-Ray Analysis), etc. on the above cut surface, chemical components and components Phases can be obtained. The chemical components may be analyzed using a glow discharge emission analyzer (generally also called a high frequency GDS).

The above-mentioned methods for measuring the thickness and chemical composition of the various coating layers 8 include a method of analyzing while digging in the film thickness direction from the surface of the metal foil by a sputtering method, or a line at the cut surface in the film thickness direction of the metal foil. An analysis or point analysis method is effective. In the method using the sputtering method, it takes too much time to measure as the measurement depth increases, but in the method of performing line analysis or point analysis of the cut surface, the concentration distribution is measured or the reproducibility is confirmed over the entire cross section. Is relatively easy. If you want to improve the accuracy of line analysis or point analysis, it is also effective to narrow the analysis interval with line analysis or expand the analysis area with point analysis. is there. Identification of the various coating layers 8 is performed by measuring the value of a standard sample (that is, concentration 100%) in advance and discriminating a region where the concentration is 50% or more by analyzing the chemical component. EPMA, EDX, GDS, AES (Auger Electron Spectroscopy), TEM (Transmission Electron Microscope, Transmission Electron Microscope), and the like can be used as analyzers used for these analyses. Note that whether or not the thicknesses of the various coating layers 8 satisfy the above-described numerical limitations is evaluated by the average thickness of the various coating layers 8. Even if the thicknesses of the various coating layers 8 do not satisfy the numerical limitation locally, they are not considered in the determination.

Next, a method for producing a steel / aluminum composite foil according to an embodiment of the present invention will be described in detail.

The manufacturing method of the steel aluminum composite foil 1 of this embodiment includes a clad rolling process in which a core material and an Al material are clad rolled to form a clad material, and the clad material is cold rolled to obtain a steel aluminum composite foil 1. A cold rolling process. Moreover, you may further have the hot dipping process for obtaining the aluminum plating steel plate which is a core material before a clad rolling process. Moreover, you may further have the film-forming process which forms the various coating layers 8 in the steel aluminum composite foil 1 after a cold rolling process. Hereinafter, each process will be described sequentially.

Hot dipping process The process of manufacturing the aluminum plating steel plate (core material) in which the aluminum plating layer (Al-containing metal layer) is arranged on the steel plate (steel layer) is not particularly limited. For example, a thermal spraying method, a sputtering method, an ion plating method, a vapor deposition method, an electroplating method, or the like may be employed. However, it is preferable to use an aluminum-plated steel sheet obtained by applying hot-dip aluminum plating to a steel sheet that is plain steel as the core material. That is, it is preferable to perform a hot dipping step of plating a steel sheet using a hot aluminum plating bath containing a chemical component containing 1 to 15% by mass of Si and the balance being Al and impurities before the clad rolling step. It is preferable to obtain an aluminum plated steel plate (core material) in which an aluminum plating layer (Al-containing metal layer) is arranged on a steel plate (steel layer) by a hot dipping process. In the molten aluminum plating method, an aluminum plated steel sheet having an aluminum plating layer can be mass-produced at low cost. Moreover, by using the molten aluminum plating bath which has said chemical component, melting | fusing point of a molten aluminum plating bath can be reduced preferably, and molten aluminum plating can be performed at a comparatively low temperature. At the interface 6 between the steel plate and the aluminum plating layer, an Fe—Al alloy layer formed by alloying Fe of the steel plate and Al of the aluminum plating layer is formed.

The thickness of the aluminum plating layer after the hot dipping process and before the clad rolling process is preferably in the range of 1 to 60 μm. Further, the lower limit of the thickness of the aluminum plating layer is more preferably 5 μm, and further preferably 10 μm. The upper limit of the thickness of the aluminum plating layer is more preferably 40 μm and even more preferably 30 μm. By setting the thickness of the aluminum plating layer within the above range, the thickness of the Al-containing metal layer 5 of the steel-aluminum composite foil 1 after the cold rolling step can be controlled within the above-described preferable range.

The thickness of the steel sheet after the hot dipping process and before the clad rolling process is preferably in the range of 50 to 2000 μm. Further, the lower limit of the thickness of the steel sheet is more preferably 100 μm and even more preferably 200 μm. The upper limit of the thickness of the steel sheet is more preferably 1500 μm, and still more preferably 1200 μm. If the thickness of the steel plate is less than 50 μm, the thickness of the steel-aluminum composite foil 1 after cold rolling may become too thin, resulting in insufficient strength. On the other hand, when the thickness of the steel plate exceeds 2000 μm, the thickness of the aluminum-plated steel plate is too thick, and a load is imposed on the subsequent process, and the number of rolling passes may increase, resulting in an increase in cost.

Also, in the hot dipping process, when two plate surfaces of a steel plate (steel layer) whose thickness direction is the normal line are steel plate surfaces, an aluminum plating layer (Al-containing metal layer) is formed on each steel plate surface. May be. When the aluminum plating layer is formed on the two steel plate surfaces of the steel plate, it is preferable that the steel aluminum composite foil 1 is hardly warped after the cold rolling subsequent to the clad rolling, so that the handling in the subsequent process is facilitated. In addition, the steel plate used for hot dip aluminum plating finally becomes the steel layer 4 of the steel aluminum composite foil 1, and the aluminum plating layer formed by hot dip aluminum plating finally has the Al-containing metal layer 5 of the steel aluminum composite foil 1. It becomes.

Clad rolling process In the clad rolling process, a core material (aluminum plated steel sheet) in which an aluminum plating layer (Al-containing metal layer) including an Fe-Al alloy layer is formed on a steel sheet (steel layer) is overlaid with an Al material. In this state, the clad rolling is performed to obtain a clad material. In the clad rolling process, an Al material may be bonded onto the aluminum plating layer (Al-containing metal layer), and the rolling conditions of the clad rolling are not particularly limited. The clad rolling temperature may be between room temperature and 500 ° C. For example, clad rolling may be performed under conditions of a heating temperature of 400 ° C. and a reduction rate of 9%, or clad rolling may be performed under conditions of a temperature of 20 ° C. (room temperature) and a reduction rate of 15%. Further, the rolling reduction may be greater than 15%.

Also, the Al material used for the clad rolling step is preferably an Al plate made of 99.0% by mass or more of Al and impurities, more preferably an Al plate made of 99.9% by mass or more of Al and impurities. Since such an Al material does not generate a eutectic structure, the surface smoothness of the surface 3a of the Al layer 3 of the steel-aluminum composite foil 1 after cold rolling can be preferably increased.

The thickness of the Al material used for the clad rolling process is preferably in the range of 1 to 1500 μm. Further, the lower limit of the thickness of the Al material is more preferably 10 μm, and still more preferably 40 μm. The upper limit of the thickness of the Al material is more preferably 1000 μm and even more preferably 500 μm. If the thickness of the Al material is less than 1 μm, it may be too thin to be handled during clad rolling. On the other hand, when the thickness of the Al material exceeds 1500 μm, the number of rolling passes for rolling to a thickness suitable as a base material increases, which may increase the cost.

Also, in the clad rolling process, when two plate surfaces (two plate surfaces of the core material) of the aluminum plating layer (Al-containing metal layer) whose thickness direction is a normal line are used as the plating surfaces, the Al materials are respectively It may be joined on the plated surface by clad rolling. When Al layers are formed on the two plating surfaces of the aluminum plating layer (Al-containing metal layer), it is difficult for warp to occur in the steel-aluminum composite foil 1 after cold rolling following clad rolling. Is easy to handle and is preferable. The Al material used for the clad rolling finally becomes the Al layer 3 of the steel aluminum composite foil 1.

Cold rolling process In the cold rolling process, a part of the Fe-Al alloy layer in the Al-containing metal layer (aluminum plating layer) is steel layer by cold rolling the clad material obtained in the clad rolling process. The steel-aluminum composite foil 1 is obtained by controlling the Fe—Al alloy grains that are separated from the (steel plate) and dispersed in the Al-containing metal layer.

Cold rolling is performed by performing a plurality of rolling passes using either tandem cold rolling equipment or reverse rolling equipment. In particular, it is preferable to perform cold rolling using a reverse rolling facility that can adjust the rolling reduction and the sheet passing speed for each rolling pass. By performing cold rolling while adjusting the rolling reduction and sheeting speed for each rolling pass, a part of the Fe—Al alloy particles can be preferably dispersed in the Al-containing metal layer. Moreover, the surface roughness Ra of the Al layer can be preferably reduced.

The sheeting speed of cold rolling is preferably set for each rolling pass in the range of 30 to 400 m / min. The plate passing speed corresponds to the energy used for plastic deformation of the clad material, and a part of the Fe—Al alloy particles can be dispersed in the Al-containing metal layer by applying a certain amount of energy. In particular, when the sheet passing speed is 30 m / min or more, a certain amount of energy can be applied to the clad material, and the Al-containing metal layer breaks the adhesion between the Fe—Al alloy grains and the steel layer, and Fe—Al The Al-containing metal layer is plastically deformed so as to envelop the alloy grains, and as a result, the Fe—Al alloy grains are dispersed in the Al-containing metal layer and / or in the Al layer. If the energy applied to the clad material is small, the Fe—Al alloy grains may remain at the interface between the steel layer and the Al-containing metal layer, and the Al-containing metal layer may wrap the Fe—Al alloy grains. There is a possibility that coarse voids may be formed without being plastically deformed. Moreover, if the plate passing speed is 400 m / min or less, there is no possibility of causing plate breakage. A more preferred cold rolling speed is 30 to 300 m / min.

In addition, the plate speed of cold rolling may be the same for all rolling passes or may be changed for each rolling pass. Furthermore, the effect of dispersing the alloy grains due to the sheet passing speed is greatly affected by the rolling pass at an earlier stage, and it becomes difficult to obtain the dispersing effect as it passes through the rolling pass. Therefore, by increasing the sheet passing speed for each rolling pass, the production efficiency can be improved while controlling the dispersion of the alloy grains within a more preferable range. On the other hand, by reducing the sheet passing speed for each rolling pass, the foil shape can be easily controlled while controlling the dispersion of alloy grains in a more preferable range.

The rolling reduction of each rolling pass of the cold rolling is preferably in the range of 15 to 40% of each rolling reduction of the first rolling pass and the second rolling pass. Moreover, it is preferable that the rolling reduction rate in the rolling pass after the second rolling pass is equal to or lower than the rolling reduction rate of the immediately preceding rolling pass. By controlling the rolling reduction of each rolling pass in this way, a sufficient amount of plastic deformation can be given to the Al-containing metal layer in each rolling pass, and dispersion of Fe—Al alloy grains can be preferably generated. Specifically, if the rolling pass rolling reduction is in the above range, the amount of plastic deformation with respect to the Al-containing metal layer is sufficient, the Fe—Al alloy layer is divided into Fe—Al alloy grains, and Al A part of the contained metal layer enters the interface between the Fe—Al alloy grains and the steel layer (base iron), and as a result, the Fe—Al alloy grains are dispersed in the Al-containing metal layer and / or in the Al layer. In particular, since a large rolling reduction cannot be obtained by work hardening in the latter half of the rolling pass, it is preferable to reduce the pressure in the first rolling pass.

If the respective rolling reductions in the first rolling pass and the second rolling pass are 15% or more, the amount of plastic deformation of the Al-containing metal layer increases, and the Fe—Al alloy layer is divided to obtain Fe—Al alloy grains. In addition, it is preferable because Fe—Al alloy grains can be dispersed in the Al-containing metal layer and / or in the Al layer. Moreover, if each rolling reduction in a 1st rolling pass and a 2nd rolling pass is 30% or less, since shape control of the steel aluminum composite foil 1 becomes easy, it is preferable.

The dispersion of Fe—Al alloy grains in the Al-containing metal layer and / or Al layer is preferably achieved when the amount of energy applied to the clad material in the cold rolling process and the amount of plastic deformation of the Al-containing metal layer are not less than a predetermined value. Is done. Therefore, it is preferable to control both the plate passing speed and the rolling reduction within the above range of the present embodiment. If only one of them is controlled, the Fe—Al alloy grains may not be dispersed.

In addition, control of the surface roughness of the Al layer 3 uses a mirror surface roll having a roll roughness (surface roughness Ra) of 10 nm or less as a work roll used in the final pass, and the Al purity of the Al layer 3 is 99.0. What is necessary is just to control in the range of the mass% or more. When the above conditions are satisfied, the surface roughness Ra of the surface 3a of the Al layer 3 of the steel-aluminum composite foil 1 after cold rolling can be preferably controlled in the range of 10 to 25 nm.

Further, the total thickness of the aluminum plating layer (Al-containing metal layer) and the thickness of the Al material before the clad rolling process is 20 μm or more, and the total rolling reduction in the clad rolling process and the cold rolling process is 65%. The above is preferable. When the above conditions are satisfied, the void 9 containing the steel-aluminum composite foil 1 after cold rolling can be preferably controlled to be less than 1 μm in terms of equivalent circle diameter.

The plastic deformation of the aluminum plating layer (Al-containing metal layer) and the Al material (Al layer) in the clad rolling process and the cold rolling process includes two deformations that are stretched in the rolling direction and deformation that fills the void. Species included. When the total thickness of the aluminum plating layer (Al-containing metal layer) and the Al material (Al layer) of the core material before the clad rolling process satisfies the above conditions, not only the deformation stretched in the rolling direction, Deformation that fills the void is also preferable. On the other hand, when the above-mentioned thickness does not satisfy the above conditions, the total volume of the aluminum plating layer (Al-containing metal layer) and the Al material (Al layer) is insufficient, so that only deformation that extends in the rolling direction occurs. As a result, voids may remain. Further, when the total rolling reduction in the clad rolling process and the cold rolling process satisfies the above conditions, a deformation that fills the void is preferably generated.

The total reduction ratio of the clad rolling process and the cold rolling process is “the total thickness of the steel plate (steel layer), the aluminum plating layer (Al-containing metal layer), and the Al material (Al layer) before the clad rolling (cladding). Is defined as the ratio of “the thickness reduced from the total thickness of the material before clad rolling to the thickness of the steel-aluminum composite foil after cold rolling” to the “total thickness of the material before rolling” To do. That is, (total rolling reduction ratio of clad rolling process and cold rolling process) = [(total thickness of steel layer before clad rolling, Al-containing metal layer and Al layer) − (steel aluminum after cold rolling) Thickness of composite foil)] / (total thickness of steel layer, Al-containing metal layer, and Al layer before clad rolling) × 100.

Film-forming process The steel aluminum composite foil 1 of this embodiment is manufactured by the clad rolling process and the cold rolling process. As a film-forming process, you may form the various coating layers 8 in the surface 3a of the Al layer 3 of the steel aluminum composite foil 1 after a cold rolling process as needed.

In order to form an AlN layer as the coating layer 8 on the surface 3a of the Al layer 3 of the steel / aluminum composite foil 1, it is preferable to perform a heat treatment. For example, the heat treatment of the steel aluminum composite foil 1 is performed at 500 to 600 ° C. in an inert gas (argon, nitrogen, mixed gas of nitrogen and hydrogen, etc.) containing 10% by volume ± 2% by volume of ammonia or hydrazine. Heating may be performed for 1 to 10 hours in the temperature range.

In order to form an Al ₂ O ₃ layer on the surface 3a of the Al layer 3 of the steel / aluminum composite foil 1, the surface 3a of the Al layer 3 is preferably anodized.

In order to form a sol-gel layer on the surface 3a of the Al layer 3 of the steel / aluminum composite foil 1, it is preferable to perform a film forming process of the sol-gel layer. For example, the ratio of the hydrogen concentration [H] (mol / l) to the silicon concentration [Si] (mol / l) in the film obtained in the final baking step is 0.1 ≦ [H] / [Si]. A sol is prepared such that ≦ 10. Next, the prepared sol is applied to the surface 3a of the Al layer 3 and dried. The steel aluminum composite foil 1 provided with the inorganic-organic hybrid film coating can be manufactured by baking after the last drying.

In order to form a laminate layer on the surface 3a of the Al layer 3 of the steel / aluminum composite foil 1, it is preferable to perform a film forming process of the laminate layer. For example, a plastic film selected from polyolefin, polyester, polyamide, polyimide, or the like is laminated on the surface 3a of the Al layer 3 via a nylon adhesive and then heated and thermocompression bonded at a pressure of about 1 MPa. By such a heat laminating method, the steel aluminum composite foil 1 having a laminate layer can be produced. In place of the plastic film selected from polyimide, a heat-resistant resin made of polyimide can be used.

As described above, according to the steel / aluminum composite foil 1 of the present embodiment, the Al-containing metal layer 5 positioned between the steel layer 4 and the Al layer 3 was dispersed away from the steel layer 4. Since the Fe—Al alloy grains 7b are included, it is estimated that the thermal expansion coefficient of the Al-containing metal layer 5 is approximately between the thermal expansion coefficient of the steel layer 4 and the thermal expansion coefficient of the Al layer 3. . Thereby, even if the steel aluminum composite foil 1 is heated to 400 ° C. or higher and receives a heat history of cooling to near room temperature, the Al-containing metal layer 5 and the like are hardly peeled off or cracked.

Moreover, in the steel aluminum composite foil 1 of this embodiment, since the steel layer 4 is coat | covered with the Al containing metal layer 5 and the Al layer 3, it is excellent in corrosion resistance. Moreover, in the steel aluminum composite foil 1 of this embodiment, since the Al layer 3 is distribute | arranged on the Al containing metal layer 5, it is excellent in surface smoothness. Further, in the steel / aluminum composite foil 1 of the present embodiment, the Fe—Al alloy layer is divided and dispersed as Fe—Al alloy grains 7, and therefore, the elastic-plastic deformability is excellent.

That is, the steel / aluminum composite foil 1 of the present embodiment simultaneously satisfies the corrosion resistance, surface smoothness, and elastoplastic deformation required as a metal foil for a base material of a solar cell or organic EL lighting, and is heated to a high temperature. Even when cooled, the peeling and cracking of the Al-containing metal layer 5 and the like are preferably suppressed. Therefore, the steel aluminum composite foil 1 of this embodiment can be suitably used as a metal foil for a base material for solar cells or organic EL lighting.

In addition, when the Al-layer 3 of the steel-aluminum composite foil 1 of the present embodiment includes Fe-Al alloy particles 7c dispersed away from the steel layer 4, the steel-aluminum composite foil 1 is heated to 400 ° C or higher. Even after receiving a thermal history that is cooled to near room temperature after being removed, peeling between the Al layer 3 and the Al-containing metal layer 5, peeling between the Al-containing metal layer 5 and the steel layer 4, cracking of the Al layer 3, and Cracking of the Al-containing metal layer 5 is further preferably prevented.

Further, when the Al layer 3 of the steel aluminum composite foil 1 of the present embodiment contains 99.0% by mass or more of Al, no eutectic structure is generated in the Al layer 3. For this reason, minute unevenness derived from the eutectic structure does not appear on the surface 3a of the Al layer 3, and the surface smoothness of the steel aluminum composite foil 1 can be further enhanced.

Moreover, when the void 9 contained in the steel aluminum composite foil 1 of the present embodiment is less than 1 μm in equivalent circle diameter, the steel layer 4 and the Al-containing metal layer 5 are peeled off, the Al-containing metal layer 5 and the Al layer 3 are Peeling, cracking of the Al-containing metal layer 5, or cracking of the Al layer 3 is further preferably prevented.

According to the method for manufacturing the steel / aluminum composite foil 1 of the present embodiment, the core material and the Al material are clad-rolled to form a clad material, and this clad material is cold-rolled to obtain Fe-- in the Al-containing metal layer 5. A part of the Al alloy layer is formed as Fe—Al alloy grains 7 b and 7 c which are separated from the steel layer and dispersed in the Al-containing metal layer 5 and / or in the Al layer 3. Therefore, it is presumed that the thermal expansion coefficient of the Al-containing metal layer 5 can be set to an intermediate level between the thermal expansion coefficient of the steel layer 4 and the thermal expansion coefficient of the Al layer 3.

Further, in the method for producing the steel-aluminum composite foil 1 of the present embodiment, the Al—Fe alloy layer present at the interface between the steel layer and the Al-containing metal layer is divided by clad rolling and cold rolling, and cold rolling is performed. Then, Fe—Al alloy grains 7 b and 7 c are dispersed in the Al-containing metal layer and / or in the Al layer 3. Therefore, the Al—Fe alloy layer that has conventionally caused the aluminum plating layer to peel or crack can be changed to a useful structure.

That is, the method for producing the steel / aluminum composite foil 1 of the present embodiment simultaneously satisfies the corrosion resistance, surface smoothness, and elastoplastic deformability required as a metal foil for a base material of a solar cell or organic EL lighting, and has a high temperature. Even when heated and cooled, it is possible to produce a metal foil for a substrate that hardly causes peeling or cracking of an Al-containing metal layer or the like.

The effects of one embodiment of the present invention will be described more specifically with reference to examples. However, the conditions in the examples are one example of conditions adopted to confirm the feasibility and effects of the present invention, and the present invention It is not limited to this one condition example. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.

(Experimental example 1)
SPCC (Steel Plate Cold Commercial) having a thickness of 0.05 to 2 mm was prepared as a steel plate. One side or both sides of this steel plate was subjected to hot-dip aluminum plating using hot-dip aluminum plating baths shown in Tables 1 to 9 to obtain aluminum-plated steel plates. At the interface between the obtained aluminum plating layer and the steel sheet, an Fe—Al alloy layer having chemical components and average thicknesses shown in Tables 1 to 9 was formed. As for chemical components of the molten aluminum plating bath, the balance other than Si shown in Tables 1 to 9 was Al and impurities. In this embodiment, “-” shown in the table indicates unused, not implemented, or not applicable.

Next, an aluminum-plated steel sheet is used as a core material, and the aluminum material shown in Tables 1 to 9 is used as a skin material on one or both sides of the core material, and the temperatures and rolling reductions shown in Tables 10 to 18 are used. A clad material was manufactured by performing clad rolling. Further, the obtained clad material was cold-rolled to produce steel aluminum composite foils of Examples 1 to 222. In addition, metal foils of Comparative Examples 1 to 6 were also produced. Tables 10 to 18 show the cold rolling conditions. In addition, cold rolling was performed with the reverse rolling mill, and rolling of the finishing pass was performed using a mirror surface roll processed with a roll roughness (surface roughness Ra) of 10 nm or less as necessary.

Regarding the steel / aluminum composite foils of Examples 1 to 222 and the metal foils of Comparative Examples 1 to 6, the cut surfaces obtained by plane cutting along the thickness direction were observed so that the plate width direction perpendicular to the rolling direction was the observation surface. . And the average thickness of the steel aluminum composite foil, the average thickness of the steel layer, the average thickness of the Al-containing metal layer, the chemical composition of the Al-containing metal layer, dispersed away from the steel layer contained in the Al-containing metal layer The grain size range of the Fe—Al alloy grains formed, the area fraction of the Fe—Al alloy grains dispersed away from the steel layer contained in the Al-containing metal layer with respect to the total Fe—Al alloy grains, the average of the Al layer Thickness, surface roughness Ra of Al layer, particle size range of Fe—Al alloy particles dispersed away from steel layer contained in Al layer, dispersed away from steel layer contained in Al layer The area fraction of Fe—Al alloy grains to the total Fe—Al alloy grains and the equivalent circle diameter of voids were measured.

The average thickness of the steel layer, Al-containing metal layer, and Al layer was determined by measuring the thicknesses of 20 arbitrarily selected locations. Further, the chemical components of the Al-containing metal layer and the Al layer were determined by performing elemental analysis using a glow discharge emission analyzer (generally also referred to as a high frequency GDS). As for the chemical components of the Al-containing metal layer, the balance other than Si shown in Tables 19 to 27 was Al and impurities. As for the chemical composition of the Al layer, the remainder other than Al shown in Tables 19 to 27 was impurities. Further, the intermetallic compounds of Fe—Al alloy grains dispersed away from the Al-containing metal layer and the steel layer contained in the Al layer are the intermetallic compounds of the Fe—Al alloy layers shown in Tables 1 to 9. It corresponded.

The particle size range and area fraction of Fe—Al alloy grains and the equivalent circle diameter of voids were determined from image analysis. The image analysis was performed at a magnification such that the observation visual field was within 200 μm in the plate width direction, and at least 15 visual fields were observed so that the total visual field in the plate width direction was 3000 μm or more. From the observation results of 15 fields of view or more, Fe—Al alloy grains dispersed away from the steel layer contained in the Al-containing metal layer, and Fe— dispersed in the Al layer, separated from the steel layer. The particle size range of the Al alloy grains was determined. Further, from the observation results of 15 or more fields of view, the area fraction of Fe—Al alloy grains dispersed away from the steel layer contained in the Al-containing metal layer with respect to the total Fe—Al alloy grains, and included in the Al layer The area fraction of the Fe—Al alloy particles dispersed away from the steel layer to the total Fe—Al alloy particles was determined.

Moreover, the void was evaluated by observing the above-mentioned cross section with SEM (Scanning Electron Microscope) and analyzing the image of the metal structure. The observation was performed in a plurality of visual fields so that the total visual field in the plate width direction was 3000 μm or more. In all of these observation fields, if no void with a circle equivalent diameter exceeding 1 μm is visually recognized, it is judged as “None”, and if any void with a circle equivalent diameter exceeding 1 μm is visually recognized, “Yes” I decided.

Evaluation of surface smoothness When the surface roughness Ra of the Al layer of the steel aluminum composite foil was 600 nm or less, it was judged that the surface smoothness was acceptable, and when it was 25 nm or less, it was judged that the surface smoothness was particularly excellent. These results are shown in Tables 19 to 27.

Further, the steel aluminum composite foils of Examples 1 to 222 were subjected to a corrosion resistance test, a 180-degree adhesion bending test, a defect number test after CIGS film formation, a CIGS conversion efficiency test, and a temperature cycle test. For the metal foils of Comparative Examples 1 to 6, the above tests were performed as necessary. Tables 28 to 36 show the results of the corrosion resistance test, 180-degree bending test, defect number test after CIGS film formation, CIGS conversion efficiency test, and temperature cycle test. In addition, about the steel aluminum composite foil in which the Al layer was formed only on one foil surface, the foil surface in which the Al layer was formed was made into the object of evaluation. Moreover, about the steel aluminum composite foil in which Al layer is formed in both foil surfaces, arbitrary one foil surface was made into the object of evaluation.

Evaluation of corrosion resistance The corrosion resistance test was evaluated by a salt spray test (SST). When 5% NaCl water maintained at 35 ° C. is sprayed on the surface of the Al layer of the steel / aluminum composite foil, VG (Very Good) when corrosion cannot be confirmed visually for 400 hours or more, G (Good) for 300 hours or more, 120 hours or more was A (Acceptable), 100 hours or more was NG (Not Good), and less than 100 hours was B (Bad). Then, VG, G, and A were accepted, and NG and B were rejected.

Evaluation of Elasto-Plastic Deformability The 180-degree contact bending test was performed by repeating 180-degree contact bending with a steel aluminum composite foil having an inner radius of zero and a bending angle of 180 °. And the frequency | count of a process with which peeling or a crack of the Al layer or Al-containing metal layer of steel aluminum composite foil was investigated. The observation of peeling or cracking of the Al layer or Al-containing metal layer of the steel / aluminum composite foil was performed by observing the bending outer peripheral portion of the steel / aluminum composite foil with an optical microscope every cycle of 180-degree contact bending. The number of times of processing when peeling or cracking of the Al layer or the Al-containing metal layer of the steel / aluminum composite foil was observed with an optical microscope was defined as the number of times of destruction. When the number of fractures was 2 times or more, it was judged that the elastoplastic deformability was acceptable, and when the number of fractures was 3 times or more, the elastoplastic deformability was judged to be particularly good.

Evaluation of peeling and cracking after heating to high temperature and cooling The defect number test after CIGS film formation was carried out by forming a Mo electrode and a CIGS photovoltaic layer on a steel aluminum composite foil. In addition, when forming Mo electrode and a CIGS photovoltaic layer, the steel aluminum composite foil was heated to 400 degreeC or more at maximum, and was cooled to room temperature. And the presence or absence of the defect which arises with the heat | fever added in a film-forming process was investigated by observing the cut surface cut | disconnected plane-wise along the thickness direction so that the plate width direction orthogonal to a rolling direction might turn into an observation surface. Observation with 10 or more fields per sample was performed with 10 samples at a magnification at which the viewing field was within 200 μm in the plate width direction. The total number of samples in which peeling of the steel layer and the Al-containing metal layer, cracking of the Al-containing metal layer, peeling of the Al-containing metal layer and the Al layer, and cracking of the Al layer occurred was measured after the CIGS film formation. It was defined as the number of defects. When the number of defects after CIGS film formation was 5 samples or less, it was judged that it was acceptable, and when the number of defects after CIGS film formation was 2 samples or less, it was judged to be particularly good.

Evaluation of CIGS photoelectric conversion efficiency A sub-module was prepared by forming a Mo electrode and a CIGS photovoltaic layer on a steel aluminum composite foil, and the CIGS photoelectric conversion efficiency was examined. CIGS photoelectric conversion efficiency is less than 7% NG (Not Good), 7% to less than 8% A (Acceptable), 8% to less than 10% G (Good), 10 to less than 12% VG (Very Good) , 12% or more was evaluated as GG (Greatly Good). Then, A, G, VG, and GG were accepted and NG was rejected.

Temperature cycle test A Mo module and a CIGS photovoltaic layer were formed on a steel / aluminum composite foil to produce a submodule, and a temperature cycle test was performed to evaluate the reliability against temperature changes. In the temperature cycle test, the above-mentioned submodule as a test material was subjected to 200 cycles of one cycle of atmospheric change that was held at −40 ° C. for 15 minutes and then held at 85 ° C. for 15 minutes. Then, the power generation efficiency of the submodule was measured before and after the 200 cycle test, and the decrease in power generation efficiency was examined. The case where the decrease in power generation efficiency of the submodule was within 5% before and after the 200 cycle test was determined as G (Good), and the case where the decrease was more than 5% was determined as NG (NotGood). NG was rejected. These results are shown in Tables 28 to 36.

(Experimental example 2)
In Experimental Example 2, an AlN layer, an Al ₂ O ₃ layer, a sol-gel layer, or a laminate layer is formed on the Al layer of the steel / aluminum composite foil produced in Experimental Example 1, and a Mo electrode and CIGS light are further formed thereon. A power generation layer was formed to produce a submodule. When forming the Mo electrode and the CIGS photovoltaic layer, the steel / aluminum composite foil was heated to 400 ° C. or higher at maximum and cooled to room temperature. With respect to these Examples 223 to 240, the withstand voltage, the surface roughness Ra, and the CIGS photoelectric conversion efficiency were examined. When the withstand voltage was 500 V or more, it was judged that the withstand voltage was excellent. When the surface roughness Ra was 25 nm or less, it was judged that the surface smoothness was particularly excellent. Further, CIGS photoelectric conversion efficiency is NG (Not Good) less than 7%, A (Acceptable) from 7% to less than 8%, G (Good) from 8% to less than 10%, VG (Very) from 10% to less than 12%. Good), 12% or more was evaluated as GG (Greatly Good). NG was rejected. These results are shown in Table 37.

The AlN layer was produced by heat treatment using an inert gas containing ammonia. The Al ₂ O ₃ layer was prepared by performing anodization with a direct current in a sulfuric acid solution.

In forming the sol-gel layer, a mixture of 10 mol of methyltriethoxysilane and 10 mol of tetraethoxysilane was used as a starting material for the preparation of sol, and 20 mol of ethanol was added to this mixture and stirred well. Thereafter, while stirring, an aqueous solution of acetic acid in which 2 mol of acetic acid and 100 mol of water were mixed was added dropwise for hydrolysis. 100 mol of ethanol was added to the sol thus obtained to obtain a final sol. The sol was applied to the surface of the steel / aluminum composite foil by the dip coating method, and then dried in air at 100 ° C. for 1 minute. Thereafter, the temperature was raised from room temperature to 400 ° C. in a nitrogen atmosphere at a rate of temperature rise of 10 ° C./min, and baked at 400 ° C. for 30 minutes to obtain a sol-gel layer.

In forming the laminate layer, the nylon adhesive was dissolved in a mixed solvent of cresol and xylene in a mass ratio of 70:30 at a concentration of 15% by mass, and the dissolved material was applied to the resin. It heat-laminated by thermocompression bonding to the steel aluminum composite foil heated to 1 MPa with the pressure of 1 MPa.

As shown in Tables 1 to 37, Examples 1 to 240 are excellent in corrosion resistance, surface smoothness, and elastoplastic deformability, and peel off Al-containing metal layers and Al layers even when heated to high temperatures and cooled. And cracks were suppressed.

On the other hand, in Comparative Examples 1 to 6, any of corrosion resistance, surface smoothness, and elastoplastic deformation is insufficient, or when the Al-containing metal layer or Al layer is peeled off when heated to high temperature and cooled And cracks occurred.

According to the said aspect of this invention, while satisfy | filling simultaneously the corrosion resistance, surface smoothness, and elastic-plastic deformability which are requested | required as a metal foil for base materials of a solar cell or organic electroluminescent illumination, it heated and cooled to high temperature Even in such a case, it is possible to provide a steel / aluminum composite foil in which peeling or cracking of an Al-containing metal layer or the like hardly occurs. Therefore, industrial applicability is high.

DESCRIPTION OF SYMBOLS 1 ... Steel aluminum composite foil 2 ... Core layer 3 ... Al layer 3a ... Surface of Al layer 3 4 ... Steel layer 4a ... Steel layer surface of steel layer 4 5 ... Al containing metal layer 5a ... Al containing metal of Al containing metal layer 5 Layer surface 6 ... Interface 7 ... Fe-Al alloy grain 7a ... Fe-Al alloy grain dispersed on interface 6 7b ... Fe-Al alloy grain dispersed in Al-containing metal layer 5 7c ... Dispersed in Al layer 3 Fe-Al alloy particles 8 ... Various coating layers 9 ... Void

Claims (15)

A core layer having a steel layer and an Al-containing metal layer formed on the steel layer;
An Al layer laminated on the Al-containing metal layer of the core layer,
When viewed in a cross section in which the thickness direction and the cutting direction are parallel, the Al-containing metal layer includes Fe—Al alloy particles dispersed and separated from the steel layer. Steel aluminum composite foil. When viewed in the cross section, the area fraction of the Fe—Al alloy grains dispersed and separated from the steel layer contained in the Al-containing metal layer is the Fe—Al alloy grain contained in the cross section. On the other hand, the steel aluminum composite foil according to claim 1, which is in a range of 7.5 area% or more and less than 50 area%. 2. The particle size of the Fe—Al alloy particles dispersed and spaced apart from the steel layer contained in the Al-containing metal layer is in the range of 0.1 to 5 μm. 2. The steel aluminum composite foil according to 2. The Fe-Al alloy particles dispersed and spaced apart from the steel layer are included in the Al layer when viewed in the cross section. Steel aluminum composite foil of description. When viewed in the cross section, the area fraction of the Fe—Al alloy grains dispersed away from the steel layer contained in the Al layer is smaller than the Fe—Al alloy grains contained in the cross section. The steel aluminum composite foil according to claim 4, wherein the steel aluminum composite foil is in a range of 7.5 area% or more and less than 40 area%. 6. The particle diameter of the Fe—Al alloy particles dispersed and separated from the steel layer contained in the Al layer is in the range of 0.1 to 5 μm. Steel aluminum composite foil of description. The Al-containing metal layer is disposed on each steel layer surface when the two outer surfaces of the steel layer having the thickness direction as a normal line are steel layer surfaces. Steel aluminum composite foil as described in any one of these. The Al layer is arranged on each of the Al-containing metal layer surfaces when two outer surfaces of the Al-containing metal layer having the thickness direction as a normal line are Al-containing metal layer surfaces. Item 8. The steel aluminum composite foil according to Item 7. The steel / aluminum composite foil according to any one of claims 1 to 8, wherein a void contained in the cross section has an equivalent circle diameter of less than 1 µm. The steel-aluminum composite foil according to any one of claims 1 to 9, wherein the chemical component of the Al-containing metal layer contains 1 to 15 mass% of Si, and the balance is made of Al and impurities. . 11. The Fe—Al alloy grain according to claim 1, wherein the Fe—Al alloy grain contains at least one intermetallic compound selected from FeAl ₃ , Fe ₂ Al ₈ Si, and FeAl ₅ Si. Steel aluminum composite foil. The steel-aluminum composite foil according to any one of claims 1 to 11, wherein the chemical component of the Al layer comprises 99.0% by mass or more of Al and impurities. The steel aluminum composite foil according to any one of claims 1 to 12, wherein the surface roughness Ra of the surface of the Al layer is 10 to 25 nm. The steel aluminum composite foil according to any one of claims 1 to 13, further comprising at least one selected from an AlN layer and an Al ₂ O ₃ layer on the surface of the Al layer. . The steel / aluminum composite foil according to any one of claims 1 to 13, further comprising at least one selected from a sol-gel layer and a laminate layer on the surface of the Al layer.

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