JP5779061B2 - Aluminum rolled material and method for producing the same - Google Patents

Description

  The present invention relates to a rolled aluminum material, particularly a high-purity aluminum rolled material and a method for producing the same.

High-purity aluminum having a purity of 99.9999% (mass ratio, the same shall apply hereinafter) or higher is used in many fields, and its application is expanding. As such an application, for example, a superconducting magnet, a cryopump or a cryogenic refrigerator that can be used at an extremely low temperature of an absolute temperature of 50K or less and requires a low electrical resistivity and / or a high thermal conductivity is known. ing. Further, high-purity aluminum is also used as a raw material used for vapor phase growth of semiconductors by MBE or the like.
For example, Patent Document 1 discloses a high-purity aluminum material having a purity level of 99.9999% or higher.
It is also known that an aluminum material of 99.999% or more obtained by refining (refining) by a three-layer electrolysis method can be obtained by further purifying it by a unidirectional solidification method. It has been.

JP 2009-242867 A

However, most of these high-purity materials are provided as cast materials. For example, they are cast for reasons such as excellent dimensional accuracy or excellent workability, and excellent thermal conductivity and electrical conductivity. There is a strong demand for a rolled material having a high purity (for example, a purity of 99.9999% or more) instead of the material.
However, almost no aluminum rolled material having a purity of 99.9999% or more is known.

  This is because steel such as tool steel typified by SKD61 defined in JIS G 4404 is used as a material for a rolling roll used for rolling in order to ensure the dimensional accuracy of the rolled material or to improve the durability of the rolling roll. Since it is necessary to use, the amount of impurities (impurity concentration) rises due to iron in the rolling roll diffusing into the aluminum material during rolling or mixing of worn roll pieces (abrasion powder). This is because the later purity becomes less than 99.9999%.

  Accordingly, the present invention provides, for example, an aluminum rolled material having a high purity of, for example, a purity of 99.9999% or more and a low iron content (iron surface contamination amount (iron surface contamination concentration)), and iron It is possible to obtain a high-purity aluminum rolled material having a purity of 99.9999% or more and low iron content (iron surface contamination amount (iron surface contamination concentration)), for example, even when using a rolling roll containing An object of the present invention is to provide a method for producing a rolled aluminum material.

  In aspect 1 of the present invention, the surface contamination concentration of iron (total surface contamination of iron) at a depth of 2 μm from the surface of each surface and a total depth of 4 μm is 100 mass ppm · μm or less, and the purity is A rolled aluminum material having a mass ratio of 99.9999% or more, wherein at least a part of the surface is covered with a plurality of thin pieces made of aluminum.

  Aspect 2 of the present invention is the rolled aluminum material according to aspect 1, wherein the flakes have a mass ratio of a purity of 99.98% or more.

  Aspect 3 of the present invention is the aluminum rolled material according to aspect 1 or 2, wherein the thin piece has a scaly shape having a rolling direction of the aluminum rolled material as a longitudinal direction.

  Aspect 4 of the present invention is characterized in that the surface contamination concentration (total amount of iron surface contamination) of iron at a depth of 2 μm from each surface and a total depth of 4 μm is 20 mass ppm · μm or less. It is an aluminum rolling material in any one of aspects 1-3.

  Aspect 5 of the present invention uses a coating step of rolling the first aluminum material to form an aluminum coating layer on the surface of the rolling roll, and the rolling roll having the aluminum coating layer, and the purity is 99 by mass. A rolling step of rolling a second aluminum material of .9999% or more, and a method of manufacturing an aluminum rolled material having a purity of 99.9999% or more by mass ratio.

Embodiment 6 of the present invention, the following (1) performs a rolling of said first Arumiumu material coating total number of paths P _t which is defined as of 15 or higher by the formula, and the second aluminum-pass rolling of 6. The manufacturing method according to aspect 5, wherein the number is 16 or more.

（ここで、Ｌ_ｎはコーティング用アルミニウム材を１パスから順にＮパスまで圧延した際の、ｎパス目の圧延前のコーティング用圧延材の長さであり、Ｌ_Ｒは、圧延ロールの周長である。）

(Here, L _n is the length of the rolling material for rolling before rolling of the n-th pass when rolling the aluminum material for coating from 1 pass to N pass in sequence, and _LR is the circumference of the rolling roll. .)

  Aspect 7 of the present invention is the method for producing an aluminum rolled material according to aspect 5 or 6, wherein the purity of the first aluminum material is 99.98% or more by mass ratio.

  Aspect 8 of the present invention is the method for producing a rolled aluminum material according to any one of aspects 5 to 7, wherein the rolling in the coating step is cold rolling.

  Aspect 9 of the present invention is the method for producing a rolled aluminum material according to any one of the aspects 5 to 8, wherein the rolling in the rolling step is cold rolling.

  A tenth aspect of the present invention is the method for producing an aluminum rolled material according to any one of the fifth to ninth aspects, wherein the rolling in the coating step is performed a plurality of times using the rolling roll.

  According to the present invention, even when a steel rolling roll having excellent durability and high dimensional accuracy of the obtained rolled material is used, iron elements can be prevented from entering the aluminum material during rolling. Therefore, according to the present invention, a high-purity aluminum rolled material having a purity of, for example, 99.9999% or more and low iron content (iron surface contamination amount (iron surface contamination concentration)) and a method for producing the same Can be provided.

It is a schematic sectional drawing which shows the manufacturing method of this invention. It is a schematic cross section of a suitable aluminum rolled material according to the present invention. It is a SEM photograph of the suitable aluminum rolled material which concerns on this invention. It is a measurement result of the iron content (iron concentration) by the depth GDMS of the sample concerning Example 1, Reference Example 2, and a comparative example. It is a measurement result of the density | concentration (iron content) of the iron by the depth GDMS of the sample which concerns on Example 3. FIG. In Example 3, it is a graph which shows the relationship between the coating total number of passes, the number of rolling passes, and the surface contamination density | concentration of iron (both surfaces total 4 micrometers) (total surface contamination of iron (both surfaces total 4 micrometers)). It is the measurement result of the density | concentration (iron content) of the iron by the depth GDMS of the sample which concerns on Example 4. FIG.

As a result of earnest examination, the inventor of this application can suppress the intrusion of iron from the rolling roll at the time of rolling to the aluminum surface part by coating the surface of the rolling roll used for rolling with aluminum in advance. Later, for example, it was found that high purity of 99.9999% or more can be maintained.
And it discovered that it became possible to give the effective aluminum coating to the surface of a rolling roll by rolling the aluminum material for a coating. Moreover, when suitable coating was implemented, it discovered that at least one part of the surface of the obtained rolling material was covered with the aluminum flake used for coating, and a rolling material with more preferable purity can be obtained.

  Details of the present invention will be described below. First, the details of the production method according to the present invention will be described, and then a suitable aluminum rolled material obtained by the production method of the present invention will be described.

1. Manufacturing Method FIG. 1 is a schematic cross-sectional view showing the manufacturing method of the present invention.
The aluminum material 3 is rolled using one set of rolling rolls 1. At least a part of the surface of the rolling roll 1 is covered with a coating layer 2 made of aluminum.
The coating layer 2 is formed by rolling a coating aluminum material different from the aluminum material 3 by using the rolling roll 1 before rolling the aluminum material 3.
And after forming the coating layer 2, it can prevent or suppress that the aluminum material 3 contacts the rolling roll 1 directly by rolling the aluminum material 3. FIG.
As a result, in the obtained aluminum rolled material (in the drawing, the portion of the aluminum material 3 on the right side of the rolling roll 1), for example, the components of the rolling roll 1 such as iron are diffused or worn. It is possible to suppress the mixing of (abrasion powder), and thus it is possible to suppress an increase in the amount of impurities (impurity concentration) of the aluminum material 3 in the rolling process.

Below, a manufacturing method is explained in full detail.
(1) Aluminum Material The aluminum material 3 used for rolling is made of aluminum having a purity of 99.9999% or more (as described above, mass ratio). Although it is not limited, a casting material is usually used, and a casting material whose surface is cut may be used.
Such a high-purity aluminum material is obtained by a known method, for example, by purifying an aluminum material having a purity of 99.999% or more obtained by refining (refining) by a three-layer electrolytic method, and further purifying it by a unidirectional solidification method. be able to.

In addition, since it is extremely difficult to measure the purity by measuring all elements, it is often present as an impurity in aluminum, and is often present as iron (Fe), silicon (Si), chromium (Cr ), The content (mass%) (concentration (mass%)) of 6 elements of molybdenum (Mo) and vanadium (V), and the content (concentration (mass%)) of these 6 elements from 100 mass%. The subtraction is used as the purity of aluminum.
The content (concentration) of these six elements can be measured by, for example, ICP emission analysis. It can also be measured by mass spectrometry such as glow discharge mass spectrometry.

Furthermore, as a method for more quantitatively evaluating the amount of iron (iron concentration) that has entered the aluminum material 3 during rolling from the rolling roll 1, measurement by depth GDMS (depth glow discharge mass spectrometry) is used. it can.
This is because one side of the obtained aluminum rolled material is subjected to GDMS analysis of the amount of iron (iron concentration) in the range of 2 μm from the surface in the depth direction, and the obtained GDMS analysis value is converted to a total value of 4 μm on both sides (unit: ppm · It can be obtained by subtracting the total 4 μm converted value of the GDMS analysis value of the aluminum material 3 before rolling from μm).
More specifically, for example, as shown in FIG. 4 according to an embodiment described in detail later, the area (ppm · μm (ppm is the mass ratio, ppm) of the depth direction GDMS analysis value (concentration profile on one side) in the range of 2 μm from the surface. The same value below))) is the integrated value (ppm · μm) of the amount of iron (iron concentration) in the range of 2 μm in depth on each side of the rolled material and 4 μm in depth on both sides. The integrated value of the amount of iron (iron concentration) in a total range of 4 μm on both sides of the iron content (iron concentration) (for example, 0.059 ppm in the examples described in detail later) of the aluminum material for rolling measured by GDMS analysis That is, the total amount of iron surface contamination (iron content) obtained by subtracting the product of iron content (iron concentration) and 4 μm (0.059 ppm × 4 μm = 0.24 ppm · μm) in the aluminum material for rolling. Surface contamination concentration) Worth can be.
Thus, the obtained total amount of surface contamination (surface contamination concentration) is useful as a means for more quantitatively evaluating the amount of iron (iron concentration) that has entered the surface of the aluminum material 3 from the rolling roll 1.
Hereinafter, in this specification, the amount of iron thus obtained (iron concentration) is referred to as “total surface contamination of iron (4 μm on both sides in total)” or “iron surface contamination concentration (4 μm on both sides in total)”. There is.

(2) Rolling roll The rolling roll 1 is a roll conventionally used for aluminum rolling. For example, a roll made of steel such as tool steel represented by SKD61 specified in JIS can be used.
In addition, the rolling roll 1 used for this invention is not limited to steel, For example, even if it uses the rolling roll 1 which consists of materials other than steel, such as a ceramic roll, the rolling roll 1 to the aluminum material 3 is used during rolling. It is possible to achieve the object of the present application to suppress the intrusion of impurities into the substrate.

(3) Coating of rolling roll Before the aluminum material 3 is rolled, an aluminum coating layer 2 is formed on the surface of the rolling roll 1. The coating of the aluminum coating layer 2 is performed by rolling an aluminum material different from the aluminum material 3 (hereinafter sometimes referred to as “aluminum material for coating”) with a rolling roll 1.

  The aluminum coating layer 2 is preferably formed using a coating aluminum material having a purity of 99.98% or more. More preferably, the purity of the aluminum material for coating is selected so that the purity of the aluminum coating layer 2 is 99.98% or more. Further, the purity of the aluminum material for coating is preferably 99.9999% or more which is equal to or higher than that of the aluminum material 3.

  The coating aluminum material is preferably used after removing the surface contamination layer by acid cleaning or alkali cleaning with a mixed acid of hydrofluoric acid and nitric acid or caustic soda (sodium hydroxide solution).

  In order to suppress the diffusion of iron from the rolling roll 1 to the aluminum coating layer 2 during coating, the coating is preferably performed by cold rolling.

The aluminum coating layer 2 preferably has a thickness of 0.2 μm or more, and more preferably has a thickness of 1 μm or more.
This is because when the thickness of the aluminum coating layer 2 is large, the intrusion of iron into the aluminum material 3 can be more reliably suppressed when the aluminum material 3 is rolled.

The coating layer 2 is preferably 80% or more of the surface portion of the rolling roll 1 that contacts the aluminum material 3 when the aluminum material 3 is rolled (the surface portion that contacts the aluminum material 3 when there is no coating layer 2). More preferably, it covers 90% or more.
This is because, when the aluminum material 3 is rolled, the aluminum material 3 and the rolling roll 1 can be reliably prevented from coming into contact with each other by covering such a wide range.

The aluminum coating layer 2 having such a high coverage of preferably 80% or more, more preferably 90% or more is dense and uniform, and can be more firmly bonded to the roll 1. .
The coverage of the rolling roll 1 with the aluminum coating layer 2 can be obtained by, for example, image analysis of an image obtained by observing the surface of the rolling roll 1 with an SEM (scanning electron microscope) or an optical microscope.

  The rolling reduction (processing rate) per pass when rolling the coating aluminum material is preferably 10% or more, and more preferably 20% or more. This is because the higher the rolling reduction, the easier the aluminum coating layer 2 adheres to the surface of the rolling roll 1, the adhesive strength between the rolling roll 1 and the aluminum coating layer 2 is increased, and a stronger aluminum coating layer 2 can be obtained. .

In addition, the aluminum material for coating is preferably rolled multiple times for the same rolling roll 1, more preferably 4 passes or more, and still more preferably 20 passes or more.
This is because a thicker aluminum coating layer 2 can be obtained by rolling a plurality of passes.
When rolling a plurality of passes, the total rolling reduction of the coating aluminum material (the rolling reduction of the entire plurality of passes) is preferably 60% or more, and more preferably 80% or more.
This is because a stronger aluminum coating layer 2 can be obtained.
In order to select a rolling condition more suitable for coating, the rolling of the coating aluminum material is usually performed at a reduction rate and the number of passes as compared with the rolling of the aluminum material 3 for obtaining the target rolled material thereafter. It is preferable to select at least one of them to be different.

-Coating total number of passes Moreover, it is preferable to use "the number of coating total passes" as a parameter | index which manages so that the aluminum coating layer 2 can be more reliably formed in the rolling roll 1. FIG.
“Number of total coating passes” means 1 to 1 when the length of the rolling material for rolling before rolling of the n-th pass is L _n when the coating aluminum material is rolled from 1 pass to N pass. The sum of L _n up to N passes (L ₁ + L ₂ + L ₃ +... L _N-1 + L _N , also referred to as “total length of rolling material for coating”) A) Value divided by _LR .

That is, the coating total pass number P _t can be expressed by the following equation (1).

The total number of coating passes indicates how many times the respective parts of the rolling roll are contacted during N-pass rolling of the rolling material for coating.
The total number of coating passes shown in the equation (1) may be expressed as an integer by rounding off the decimal point for the sake of simplicity, for example.

The larger the total number of coating passes, the more the rolling roll 1 comes into contact with the coating aluminum material a greater number of times, so that the aluminum coating layer 2 can be formed more reliably.
The total number of coating passes is preferably 15 or more. Since the rolling roll 1 comes into sufficient contact with the coating aluminum material, a sufficient aluminum coating layer 2 can be more reliably formed when the total number of coating passes is 15 or more.
More preferably, the total number of coating passes is 15-60. This is because, within this numerical range, a sufficient aluminum coating layer 2 can be formed more reliably, and the possibility of saturation of the effect and repeated unnecessary rolling can be suppressed.

  In addition, when the aluminum coating layer 2 is formed by rolling so that the total number of coating passes is 15 times or more, the purity of the coating aluminum material to be used is preferably 99.98% or more (3N8). This is because the surface contamination concentration of iron in the aluminum material 3 after rolling (total amount of surface contamination of iron) can be reduced to a very low level of, for example, 20 ppm · μm or less.

(4) Rolling Aluminum Material 3 In the embodiment shown in FIG. 1, rolling is performed using a set of rolling rolls 1 having a coating layer 2 on the surface. In FIG. 1, the direction of the arrow x in the figure is the rolling direction.
The rolling may be performed under any conditions as long as the conditions are used for rolling the aluminum material 3 (pure aluminum).
The rolling reduction per pass is preferably 10% or more. Further, it is preferable to perform a plurality of passes of rolling. When performing multiple passes of rolling, the total rolling reduction is preferably 80% or more.

Further, in the embodiment shown in FIG. 1, rolling is performed using one set of rolling rolls 1, but when performing multiple-pass rolling, a plurality of sets of rolling rolls 1 are continuously arranged and continuous rolling is performed. May be.
When performing continuous rolling, it is preferable to form an aluminum coating layer 2 on each of a plurality of sets of rolling rolls 1.

The rolling is preferably performed by cold rolling. This is because the diffusion of iron from the rolling roll 1 can be more easily suppressed.
In hot rolling, since iron diffuses more easily from the rolling roll 1, the purity of the obtained rolled material is less than 99.9999% even if the purity of the aluminum material 3 is 99.9999% or more. There is a case.
However, even in this case, the purity of the obtained rolled material is clearly higher than that in the case where the rolling roll 1 is rolled without forming the aluminum coating layer 2.

Then , even if it hot-rolls using the rolling roll 1 in which the aluminum coating layer 2 was formed , if it is embodiment which the purity of the obtained rolling material becomes 99.9999% or more, it is contained in this invention. .
When performing hot rolling, the rolling temperature is preferably 400 to 550 ° C. This is because if the rolling temperature is less than 400 ° C., the aluminum material is not sufficiently softened, and if the rolling temperature exceeds 550 ° C., the aluminum material may stick to the rolling roll and workability is reduced.

In addition, it cannot be overemphasized that the rolling material said by this specification means the material obtained by performing rolling of 1 pass or more using a rolling roll.
In many cases, the rolled material has any one or more of the following characteristics, and since it has at least one or more of these characteristics, it can be recognized as a rolled material. However, these features do not limit the rolled material, and the absence of any of these features does not mean that it is not immediately a rolled material.

i) It has a structure having a specific crystal orientation called a rolling texture. The preferred crystal orientation differs between cold rolling and hot rolling.
Cold rolling texture: A composite orientation (two orientations) of (112) [11-1] and (011) [21-1] is the preferred orientation.
Hot rolling texture: (011) [21-1] is the preferred orientation.
ii) The dislocation density in the crystal is significantly increased by plastic deformation due to rolling. In the homogenized ingot, the dislocation density is 10 ⁶ to 10 ⁸ / cm ² , but in the rolled material, the dislocation density reaches 10 ¹⁰ to 10 ¹² / cm ² .
iii) Crystal grains stretched in the rolling direction by rolling are observed.

-Preferable rolling conditions when the coating total number of passes is 15 times or more As described above, the coating total number of passes is preferably 15 times or more when coating the coating aluminum material. A reliable aluminum coating layer 2 can be formed more reliably.

  In this case, it is preferable to roll the aluminum material 3 for 16 passes or more. Thus, by rolling 16 passes or more, the surface contamination concentration of iron (total amount of surface contamination of iron) can be reduced to a very low level of, for example, 20 ppm · μm or less.

  Although the reason for this is not clear, the reason that the inventors of the present application presume is as follows. It should be noted that the following reason is a reason that the inventors of the present application infer from the knowledge obtained at the present time, and is not intended to limit the technical scope of the present invention.

  When rolling is repeated at an appropriate rolling reduction, the aluminum material 3 is rolled relatively uniformly and the surface area is increased. On the other hand, since a sufficient aluminum coating layer 2 is formed on the surface of the rolling roll 1 under the condition that the total number of coating passes is 15 or more, even if rolling is repeated and the number of rolling passes increases, the rolling roll 1 Intrusion of iron into the aluminum material 3 is sufficiently suppressed.

As a result, the total volume of iron (iron concentration) existing on the surface of the aluminum material 3 does not increase so much, and the volume of the surface portion of the aluminum material 3 (for example, a depth of 2 μm from the surface of each surface, the total of both surfaces) Since the volume in the depth range of 4 μm increases, the iron surface contamination concentration (total amount of iron surface contamination) decreases. In particular, by setting the number of rolling passes to 16 or more, the iron surface contamination concentration (total amount of iron surface contamination) can be reduced to a very low level of, for example, 20 ppm · μm or less.
In consideration of this mechanism, the total rolling reduction is preferably 90% or more.

2. Suitable Rolled Material FIG. 2 is a schematic cross-sectional view of a suitable aluminum rolled material (part) obtained by the manufacturing method described above.
The aluminum rolled material 3a obtained by rolling the aluminum material 3 under the above-described conditions has a surface covered with a plurality of aluminum thin pieces 2a. In FIG. 2, only one surface of the rolled material 3a is shown, but the other surface is similarly covered with a plurality of aluminum flakes 2a.

FIG. 3A is a SEM observation result of the surface of the aluminum rolled material according to Example 1-2, the details of which will be described later, and FIG. 3B is the aluminum rolled material according to Comparative Example 1-1, whose details will be described later. It is a SEM observation result of the surface of this. The surface of the rolled material shown in FIG. 3 (a) is covered with aluminum flakes having a scaly shape extending in the rolling direction (left-right direction in the photograph), that is, the rolling direction as the longitudinal direction. On the other hand, the rolled material in FIG. 3 (b), which were rolled without forming the aluminum coating layer 2 on the surface of the rolling roller 1, A aluminum flakes on the surface of the rolled material is not observed.

  When forming the aluminum coating layer 2, the surface of the rolled material 3a is covered with the aluminum flakes 2a when the aluminum coating layer 2 is formed under the above-mentioned preferable forming conditions, for example, the coverage is 80% or more. There are many cases.

This is because when the aluminum coating layer 2 having a high coverage ratio and / or a sufficient thickness is formed, a part of the aluminum coating layer 2 is peeled off during rolling to cover the surface of the rolled material 3a as the aluminum flakes 2a.
That is, the rolling material 3a covered with the aluminum flakes 2a means that the aluminum coating layer 2 was sufficiently formed, and thus the intrusion of iron from the rolling roll 1 is sufficiently suppressed. It shows that.
Moreover, since the aluminum flakes 2a are peeled off from the aluminum coating layer 2 and then pressed by the rolling roll 1, they are pressed into the surface of the rolled material 3a and fixed to the surface of the rolled material 3a. And the aluminum flakes 2a have the shape extended in the rolling direction.

  Therefore, the purity of the aluminum rolled material 3a is preferably 99.9999% or more.

Further, as described above, the aluminum coating layer 2 preferably has a purity of 99.98% or more, more preferably 99.9999% or more, and the aluminum flakes 2a preferably have a purity of 99.98% or more. It is 98% or more, more preferably 99.9999% or more.
Further, the rolled material 3a covered with the aluminum flakes 2a in this way has the above-mentioned total amount of iron surface contamination (both surfaces total 4 μm) (iron surface contamination concentration (both surfaces total 4 μm)) of 100 ppm · μm or less. Is possible.

  In addition, the higher the coverage of the surface of the aluminum rolled material 3a by the aluminum flakes 2a, the more reliably the intrusion of iron from the roll 1 can be prevented. The coverage of the aluminum rolled material 3a surface by the aluminum flakes 2a is preferably 60% or more, more preferably 80% or more.

  The coverage of the surface of the aluminum rolled material 3a with the aluminum flakes 2a can be determined by image analysis of an image obtained by observing the surface of the rolling roll 1 with an SEM (scanning electron microscope) or an optical microscope, for example.

  Depending on the application of the aluminum rolled material, it may be preferable that the aluminum flakes 2a do not exist on the surface. When used for such applications, the aluminum rolled material 3a is removed after mechanically removing the aluminum flakes 2a, for example, by polishing, or after chemically removing the aluminum flakes 2a, for example, by acid etching or alkaline etching. It is possible to use.

1. Example 1 (cold rolled material) and Reference Example 2 (hot rolled material)
(1) Aluminum material for rolling 5N (Five Nine) aluminum having a purity of 99.999% or more obtained by refining by a three-layer electrolytic method is purified by a unidirectional solidification method and 6N (Six Nine) having a purity of 99.9999% or more. ) An aluminum material was obtained.
More specifically, with respect to six impurities, iron is 0.059 ppm, silicon is 0.37 ppm, manganese is 0.004 ppm, chromium is 0.020 ppm, molybdenum is 0.001 ppm, and vanadium is 0.016 ppm. It was 0.47 ppm.

  This aluminum material was cut into a width of 60 mm, a length of 80 mm, and a thickness of 10 mm, and then washed with hydrofluoric acid (dissolution cleaning), washed with water, and dried to obtain an aluminum material 3 for rolling.

(2) Formation of aluminum coating layer As shown below, the aluminum coating layer 2 was formed on the surface of the rolling roll 1 by rolling of 4 passes or 25 passes. Moreover, the rolling roll 1 which does not form the aluminum coating layer used for comparative example sample preparation was also prepared.
i) 4 passes: 6N aluminum having the same purity 99.9999% or more as the aluminum material 3 for rolling was cut into a width of 60 mm, a length of 80 mm, and a thickness of 1 mm, washed with hydrochloric acid, and reduced by 18% per pass. Then, cold rolling of 4 passes was performed to a thickness of 0.5 mm, and an aluminum coating layer 2 having a purity of 99.9999% or more (6N) was formed on the rolling roll 1.
ii) 25 passes: 6N aluminum having the same purity 99.9999% or more as the aluminum material 3 for rolling is cut into a width of 80 mm, a length of 60 mm, and a thickness of 10 mm, washed with hydrochloric acid, and reduced by 18% per pass. Then, 25 passes of cold rolling to a thickness of 0.5 mm were performed, and an aluminum coating layer 2 having a purity of 99.9999% or more (6N) was formed on the rolling roll 1.
The coverage of the aluminum coating layer 2 is estimated to be 80% or more.
iii) Without aluminum coating layer: After polishing the rolling roll with emery paper, thoroughly spraying rolling oil ("Daffney Oil AL-41" manufactured by Idemitsu Kosan Co., Ltd.) to wash away the abrasion powder adhering to the rolling roll, and then A rolling roll was prepared by wiping with a paper waste.
The used rolling roll 1 was made of SKD61 steel defined in JIS and had the components shown in Table 1.

(3) Rolling Rolling was performed using the aluminum material 3 for rolling described above. Rolling was performed from a thickness of 10 mm to a thickness of 0.5 mm by rolling with 8 passes (32% reduction per pass) or 16 passes (18% reduction per pass).
Rolling was performed by either cold rolling or hot rolling described below.
i) Cold rolling: Rolled in the length direction at room temperature. As the rolling oil, “Daffney Oil AL-41” made by Idemitsu Kosan Co., Ltd., which mainly contains petroleum-based carbohydrates, was used.
ii) Hot rolling: After heating the aluminum material 3 for rolling in an HP-60 type high temp oven manufactured by Asahi Kagaku Co., Ltd. at 500 ° C. for 10 minutes for each pass, it is immediately taken out from the high temp oven and length Hot rolling was performed in the direction. As the rolling oil, “Daffney Oil AL-41” made by Idemitsu Kosan Co., Ltd., which mainly contains petroleum-based carbohydrates, was used.

  Table 2 shows the conditions for forming the aluminum coating layer and the rolling conditions of the sample prepared.

  Among the obtained rolled materials, in Example 1-1, an aluminum flake 2a having a purity of 99.9999% was observed. In Example 1-2, aluminum flakes 2a having a purity of 99.9999% were observed. In common with Examples 1-1 and 1-2, the coverage of the aluminum flakes 2a is estimated to be 60% or more.

(4) Purity measurement From each of the obtained rolled material samples, 2 to 3 samples for analysis having a width of 24 mm, a length of 24 mm and a thickness of 0.5 mm were cut out from the vicinity of the center in the width direction and the length direction, and ethanol was obtained. After the surface was washed with, it was naturally dried to obtain a sample for analysis.

  The content (concentration) of iron and chromium in the bulk (whole sample) was determined by ICP mass spectrometry. Further, the contents (concentrations) of four elements of silicon, manganese, molybdenum and vanadium were determined by ICP emission analysis.

  By measurement with depth GDMS, the iron content (iron concentration) was determined from the sample surface to a depth of 2 μm every 0.1 μm. From the measurement results obtained, the total amount of iron surface contamination (both sides total 4 μm) (iron surface contamination concentration (both sides total 4 μm)) was calculated.

FIG. 4 shows the measurement results of iron content (iron concentration) by depth GDMS. The vertical axis indicates the iron content (ppm) (iron concentration (ppm)) on a logarithmic scale.
Table 3 shows the iron content in the bulk (iron concentration), the impurity content in the bulk (total content of 6 elements) (impurity concentration (total concentration of 6 elements)), and the total surface contamination of iron (total on both sides 4 μm) (iron Of surface contamination (total of 4 μm on both sides)).

In both the cold rolling and the hot rolling, the example sample in which the aluminum coating layer is formed has an iron content in the bulk (iron concentration), an impurity content in the bulk (impurity concentration), and an iron surface contamination amount. In any of the (iron surface contamination concentration), the value is lower than that of the sample that did not form the aluminum coating layer, and iron intrusion from the rolling roll is suppressed, and the amount of impurities (impurity concentration) is small. You can see that
In particular, Examples 1-1, 1-2, 1-3, and Comparative Example 1-1 in which cold rolling was performed have an impurity amount (impurity concentration) of 1 ppm or less. In Examples 1-1, 1-2, and 1-3 in which cold rolling was performed, the total amount of iron surface contamination (iron surface contamination concentration) was 100 ppm · μm or less.
Although there is no clear limitation or standard for the amount of surface contamination (surface contamination concentration) depending on the application, iron as a contaminating element has an adverse effect on the characteristics even with a small amount, so the depth of 2 μm from the outermost surface as a measure of surface contamination It is considered that the total amount of iron surface contamination (iron surface contamination concentration) at a total of 4 μm on both sides is preferably 100 ppm · μm or less. Therefore, although the impurity amount (impurity concentration) of Comparative Example 1-1 is 1 ppm or less, the total amount of surface contamination (surface contamination concentration) exceeds 100 ppm · μm, which is not preferable.

2. Example 3
In order to examine the influence of the total number of coating passes and the number of passes during rolling of the aluminum material 3 on the surface contamination concentration of iron (total amount of iron surface contamination), a sample of Example 3 was prepared.

(1) Formation of Aluminum Coating Layer After cutting the 6N rolling aluminum material shown in Example 1 and Reference Example 2, the aluminum material for coating having a length of 500 mm × width of 100 mm × thickness of 2 mm was washed with hydrochloric acid. Got.
Using the same set of rolling rolls 1 as in Example 1 and Reference Example 2, this coating aluminum material was rolled to form an aluminum coating layer 2 on the surface of the rolling roll 1. The peripheral length of the rolling roll 1 was 500 mm.

Table 4 shows the rolling conditions used to form the coating layer 2, more specifically, the total number of coating passes and the actual number of passes.
Using the above-described coating aluminum material having a length of 500 mm, rolling was performed for 4 to 20 passes shown in Table 4 (“actual number of rolling passes” in Table 4) with a rolling reduction per pass of 5%. .

  Table 4 shows the total number of coating passes (rounded to the nearest whole number) obtained from equation (1).

(2) Rolling Cold rolling was performed using the aluminum material 3 for rolling shown in Example 1 and Reference Example 2. Table 4 shows the number of rolling passes.
When the number of rolling passes is 1, it means that rolling was performed from 10 mm to 8 mm in 1 pass (20% reduction per pass).
When the number of rolling passes is 4, it means that rolling was performed at a thickness of 10 mm to a thickness of 6 mm by 4 passes (20% reduction per pass).
When the number of rolling passes is 8, it means that rolling was performed at 8 passes (20% reduction per pass) from a thickness of 10 mm to a thickness of 2 mm.
When the number of rolling passes is 16, it means that rolling was performed at a thickness of 10 mm to a thickness of 0.5 mm with 16 passes (20% reduction per pass).

  As the rolling oil, “Daffney Oil AL-41” made by Idemitsu Kosan Co., Ltd., which mainly contains petroleum-based carbohydrates, was used.

(3) Purity measurement Width 24 mm × length 24 mm × thickness 8 mm, thickness 6 mm, 2 mm, 0 mm from the vicinity of the center in the width direction and the length direction of the obtained rolled material samples of Examples 3-1 to 3-14. Two to three 5 mm samples for analysis were cut out, the surface was washed with ethanol, and then naturally dried to obtain samples for analysis.

  By measurement with depth GDMS, the iron concentration (iron content) was determined from the sample surface to a depth of 2 μm every 0.1 μm. From the measurement results obtained, the iron surface contamination concentration (both sides total 4 μm) (the total amount of iron surface contamination (both sides total 4 μm)) was calculated.

FIG. 5 shows the measurement results of iron concentration by depth GDMS. The vertical axis indicates the iron concentration (ppm) (iron content (ppm)) on a logarithmic scale.
Table 4 shows the iron surface contamination concentration (total of 4 μm on both sides) (total amount of iron surface contamination (total of 4 μm on both sides)).

FIG. 6 is a graph showing the relationship between the total number of coating passes and the number of rolling passes and the iron surface contamination concentration (both sides total 4 μm) (the total amount of iron surface contamination (both sides total 4 μm)).
The vertical axis indicates the total number of coating passes, and the horizontal axis indicates the number of rolling passes. Circles in the graph indicate the total number of coating passes determined from the vertical and horizontal axes, and the surface contamination concentration of iron (4 μm total on both sides) (total surface contamination on both sides (4 μm total on both sides)). This is visually shown by the size of the radius of the circle, and the surface contamination concentration of iron (both sides total 4 μm) (the total amount of iron surface contamination (both sides total 4 μm)) is shown numerically next to the circle.

As can be seen from Table 4 and FIG. 6, all the samples according to Example 3 have an iron surface contamination concentration (total amount of iron surface contamination) of 100 ppm · μm or less.
As can be seen from FIG. 6, all samples with a total coating pass number of 15 or more and a rolling pass number of 16 or more have a remarkable iron surface contamination concentration (total iron surface contamination) of 20 ppm · μm or less. It can be seen that it is low.

3. Example 4
In addition, a sample of Example 4 was prepared in order to examine the influence of the coating aluminum material on the iron surface contamination concentration (total amount of iron surface contamination).

(1) Formation of aluminum coating layer Three types of purity aluminum materials for coating shown in Table 5 were used.
The 5N coating aluminum material was obtained by refining commercially available high-purity aluminum by a three-layer electrolytic method. Concentrations (contents) of 6 elements of impurities in the obtained 5N coating aluminum material are 1.0 ppm for iron, 1.5 ppm for silicon, 0.014 ppm for manganese, 0.055 ppm for chromium, and 0.002 ppm for molybdenum. Vanadium was 0.026 ppm, and the total of the 6 elements was 2.60 ppm.

  The aluminum material for coating of 3N8 was obtained by refining commercially available high-purity aluminum by a unidirectional solidification method. Concentrations (contents) of 6 elements of the obtained 3N8 (purity 99.98% level) coating aluminum material were 13 ppm for iron, 30 ppm for silicon, 2.0 ppm for manganese, 3.3 ppm for chromium, and molybdenum. Was 0.57 ppm, vanadium was 3.1 ppm, and the total of 6 elements was 52.0 ppm.

  The 2N8 (purity 99.8% level) aluminum material for coating was obtained by refining commercially available high-purity aluminum by a unidirectional solidification method. Conditions such as unidirectional solidification segregation are different from those of the 3N8 material described above. The concentration (content) of the 6 impurities of the obtained 2N8 coating aluminum material was 680 ppm for iron and 10 ppm for chromium, and the total of the 6 elements was 1370 ppm.

  Using the same set of rolling rolls 1 as in Example 3, each coating aluminum material was rolled to form an aluminum coating layer 2 on the surface of the rolling roll 1.

Table 5 shows the rolling conditions used to form the coating layer 2, more specifically, the total number of coating passes and the actual number of passes.
Each aluminum material for coating was washed with hydrochloric acid after cutting. The dimensions after washing with hydrochloric acid were 500 mm long × 100 mm wide × 2 mm thick.
Using the aluminum material for coating having a length of 500 mm, rolling was performed for 20 passes as shown in Table 5 (“Actual number of rolling passes” in Table 5) with a rolling reduction per pass of 5%.

  Then, the total number of coating passes (rounded to the nearest whole number) obtained from the equation (1) was 40 as shown in Table 5.

(2) Rolling Cold rolling was performed using the aluminum material 3 for rolling shown in Example 1 and Reference Example 2. The number of rolling passes was 16, as shown in Table 5.
Rolling was performed from 16 mm thickness to 0.5 mm thickness by 16 passes (20% reduction per pass ) .

  As the rolling oil, “Daffney Oil AL-41” made by Idemitsu Kosan Co., Ltd., which mainly contains petroleum-based carbohydrates, was used.

(3) Purity measurement An analytical sample having a width of 24 mm, a length of 24 mm and a thickness of 0.5 mm was obtained from the vicinity of the central portion in the width direction and the length direction of the obtained rolled material samples of Examples 4-1 to 4-3. Two to three sheets were cut out, the surface was washed with ethanol, and then naturally dried to obtain an analytical sample.

  By measurement with depth GDMS, the iron concentration (iron content) was determined from the sample surface to a depth of 2 μm every 0.1 μm. From the measurement results obtained, the iron surface contamination concentration (both sides total 4 μm) (the total amount of iron surface contamination (both sides total 4 μm)) was calculated.

FIG. 7 shows measurement results of iron concentration (iron content) by depth GDMS. The vertical axis indicates the iron concentration (ppm) (iron content (ppm)) on a logarithmic scale.
Table 5 shows the surface contamination concentration of iron (both sides total 4 μm) (total amount of iron surface contamination (both sides total 4 μm)).

  As can be seen from Table 5, all the samples according to Example 4 have an iron surface contamination concentration (total amount of iron surface contamination) of 100 ppm · μm or less. Further, in a sample having a total coating pass number of 15 or more and a rolling pass number of 16 or more, if the purity of the coating aluminum material used is 99.98% or more, the surface contamination concentration of iron is more surely achieved. It can be seen that (total amount of iron surface contamination) can be reduced to 20 ppm · μm or less.

  According to the present invention, there is provided a high-purity aluminum material that can be used as a material for vapor phase growth of a semiconductor such as a member such as a superconducting magnet, a cryopump or a cryogenic refrigerator, and MBE, and a method for producing the same. The

DESCRIPTION OF SYMBOLS 1 Roll roll 2 Aluminum coating layer 2a Aluminum flake 3 Aluminum material 3a Aluminum rolled material

Claims (10)

The surface contamination concentration of iron (total surface contamination of iron) at a depth of 2 μm from the surface of each surface and a total depth of 4 μm is 100 mass ppm · μm or less, and the purity is 99.9999% by mass. The above aluminum rolled material,
An aluminum rolled material, wherein at least a part of the surface is covered with a plurality of thin pieces made of aluminum.   The rolled aluminum material according to claim 1, wherein the flakes have a mass ratio of 99.98% or more.   The rolled aluminum material according to claim 1 or 2, wherein the thin piece has a scaly shape with a rolling direction of the rolled aluminum material as a longitudinal direction.   4. The surface contamination concentration of iron (total surface contamination of iron) at a depth of 2 μm from the surface of each surface and a total depth of 4 μm is 20 mass ppm · μm or less. The rolled aluminum material according to claim 1. A coating step of rolling the first aluminum material to form an aluminum coating layer on the surface of the rolling roll;
A rolling step of rolling a second aluminum material having a purity of 99.9999% or more by mass ratio using the rolling roll having the aluminum coating layer;
A method for producing a rolled aluminum material having a purity of 99.9999% or more by mass ratio. Below (1) performs a rolling of said first Arumiumu material coating total number of paths P _t which is defined as of 15 or higher by the formula, and the path number of the rolling of the second aluminum is 16 or more The manufacturing method of Claim 5 characterized by these.

(Here, L _n is the length of the rolling material for rolling before rolling of the n-th pass when rolling the aluminum material for coating from 1 pass to N pass in sequence, and _LR is the circumference of the rolling roll. .)
  The method for producing a rolled aluminum material according to claim 5 or 6, wherein the purity of the first aluminum material is 99.98% or more by mass ratio.   The method for producing a rolled aluminum material according to any one of claims 5 to 7, wherein the rolling in the coating step is cold rolling.   The method for producing an aluminum rolled material according to any one of claims 5 to 8, wherein the rolling in the rolling step is cold rolling.   The rolling method of the said coating process is performed in multiple times using the said rolling roll, The manufacturing method of the aluminum rolled material of any one of Claims 5-9 characterized by the above-mentioned.

Images