JP2009037950A - High corrosion resistance copper coated aluminum composite wire - Google Patents

Abstract

The object of the present invention is to solve the problem of galvanic corrosion occurring in a Cu-coated Al composite wire by using, as a core material, an Al-Cu alloy that reduces the potential difference from the Cu coating. Another object of the present invention is to provide a Cu-coated Al composite wire that has excellent corrosion resistance and is lightened by reducing the Cu coverage even when applied to a Cu-coated Al composite wire manufactured by a Cu plating method.
This is solved by forming a highly corrosion-resistant Cu-coated Al composite wire in which a Cu coating is provided on the core material of an Al—Cu alloy containing 2 to 4% by mass of Cu.
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Description

  The present invention provides a copper-coated aluminum composite wire (hereinafter referred to as Cu-coated Al) having a particularly high corrosion resistance, in which a core material made of an aluminum-copper alloy (hereinafter referred to as Al-Cu alloy) is provided with a copper coating (hereinafter referred to as Cu coating). Compound line).

In recent years, with the miniaturization and weight reduction of electronic device parts and the like, wiring materials used for these are also required to be small and light. For Cu-coated Al composite wire, which is a typical lightweight wiring material, copper is welded with a copper tape (hereinafter referred to as Cu tape) vertically attached to a commonly used aluminum core material (hereinafter referred to as Al core material). In the tape clad method (hereinafter referred to as Cu tape clad method), the Cu tape needs to be thick to some extent in order to form and weld the Cu tape, which has hindered weight reduction. For this reason, a copper plating method (Cu plating method) has been proposed instead of the Cu tape. For example, it is a technique as described in Patent Document 1. According to such a plating method, the amount of electricity at the time of plating can be adjusted. Therefore, it has become possible to manufacture a thin Cu plating layer by controlling the amount of Cu plating. For this reason, a Cu-coated Al composite wire having a small Cu coverage has been obtained. A technique for reducing the weight by improving the Al core material has also been proposed. For example, as described in Patent Document 2, a Cu-coated Al composite wire using an Al alloy added with a specific amount of magnesium as a core material.
However, the Cu-coated Al composite wire obtained by any method or the like inevitably suffers from the problem of galvanic corrosion of Cu and Al at the end portion due to its structure. Galvanic corrosion is corrosion caused by the formation of a corrosion cell between different types of metals, so that the larger the difference in the natural potential of the metal used, the more susceptible it is. For example, the natural potential of pure Al in seawater is -0.83 vs. SCE, which is considerably lower than that of Cu -0.2 vs. SCE, so that Cu corrosion is accelerated by Cu. Further, in the case of the Cu-coated Al composite wire obtained by the Cu plating method described above, the Cu coating is considerably thinned, so that galvanic corrosion in which the Al core material is exposed is regarded as a problem even in places other than the terminal portion. ing.
Japanese Patent No. 3470795 JP-A-4-230905

  Therefore, the problem to be solved by the present invention is to solve the above-mentioned problem of galvanic corrosion occurring in the Cu-coated Al composite wire by using, as a core material, an Al alloy whose potential difference from the Cu coating is small. It is. Another object of the present invention is to provide a weight-reduced Cu-coated Al composite wire that has excellent corrosion resistance even when applied to a Cu-coated Al composite wire manufactured by a Cu plating method.

  The problem to be solved is a highly corrosion-resistant Cu-coated Al composite wire in which a Cu coating is formed on a core material of an Al—Cu alloy containing 2 to 4% by mass of Cu as described in claim 1. Is solved. In addition, as described in claim 2, the Cu coating of the high corrosion resistance Cu-coated Al composite wire described in claim 1 is achieved by using a highly corrosion-resistant Cu-coated Al composite wire formed by plating. Is done.

  Since the Cu-coated Al composite wire in which the Cu coating is provided on the core material of the Al-Cu alloy containing 2 to 4% by mass of Cu as in the present invention described above, the natural potential difference between Cu and the Al core material Can be made closer to each other, and the occurrence of galvanic corrosion can be suppressed. In addition, by forming a Cu coating on the core of an Al-Cu alloy containing 2 to 4% by mass of Cu by a plating method, the problem of galvanic corrosion does not occur and the weight of the Cu-coated Al composite wire is reduced. Therefore, it is possible to cope with lighter and smaller electronic device parts.

  The present invention is described in detail below. The invention described in claim 1 is a highly corrosion-resistant Cu-coated Al composite wire in which a Cu coating is provided on a core material of an Al—Cu alloy containing 2 to 4% by mass of Cu. In this way, by using an Al—Cu alloy with a specific amount of Cu added instead of the pure Al core material used in the past, the natural potential difference with Cu can be reduced and the occurrence of galvanic corrosion. Can be suppressed. More specifically, what was a natural potential of pure Al in seawater of a conventional Cu-coated Al composite wire -0.83 vs. SCE is an Al-Cu alloy containing 2 to 4% by mass of Cu. As a result, the natural potential becomes (approximately −0.75 vs. SCE or less), which is close to the natural potential of Cu in seawater -0.2 vs. SCE.

This will be described in more detail. As described above, the conventional Cu-coated Al composite wire has a problem of galvanic corrosion at the terminal portion, and the Cu-coated Al composite wire in which the Cu coating is manufactured by the Cu plating method in order to cope with lighter and smaller size, There is concern about galvanic corrosion due to the thin Cu coating. In view of this, the inventors considered that this problem can be solved by bringing the natural potential of the Al core material closer to the natural potential of Cu, and various studies were conducted. As a result of examining various Al alloys as the Al core material, it was found that an Al-Cu alloy is preferably used. Therefore, experiments such as galvanic corrosion were conducted on various Al—Cu alloys with different amounts of Cu. As a result, it was found that it is most preferable to use an Al—Cu alloy having a Cu content of 2 to 4 mass% as a core material. This is because when the Cu content is less than 2% by mass, the corrosion resistance of pure Al does not change much, and when the Cu content exceeds 4% by mass, there is a problem of the solid solubility limit of Cu in Al. It was found that an intermetallic compound may be generated, which is not preferable. In addition, the Cu-coated Al composite wire of the present invention was satisfactory in mechanical properties such as tensile strength. As a result, the method for forming the Cu coating of the resulting Cu-coated Al composite wire is not limited to the conventional Cu tape clad method, but also a Cu plating method that can reduce the weight of the Cu coating to reduce weight. Any of these methods can be used, and the coverage can be used as a Cu-coated Al composite wire in which a Cu coating in a wide range of 5 to 15% is formed. In particular, as described in claim 2, by performing Cu coating of a highly corrosion-resistant Cu-coated Al composite wire by a Cu plating method, the Cu coating is a highly corrosion-resistant Cu-coated Al composite wire, and the Cu coating is thinly formed by a plating method. It is also useful as a Cu-coated Al composite wire that can cope with the reduced weight and size. In other words, Cu coated Al composite wire thinly coated with a Cu coverage of less than 10% does not cause the problem of galvanic corrosion, and its weight (%) is compared with Cu coated Al composite wire manufactured by the copper tape clad method. Thus, it can be reduced by about 17%. Specifically, the copper coating amount per unit of the Cu-coated Al composite wire having a copper coating amount of 15% by the copper tape cladding method is 3.63 g / cm ³ , whereas the copper coating amount by the plating method is 5 The copper coating amount per unit of the% Cu-coated Al composite wire is 3.01 g / cm ³ .

Hereinafter, the effects of the present invention will be shown by Examples and Comparative Examples described in Table 1.
Example 1 A rough drawn wire (Φ9.5 mm) of an Al alloy containing 2% by mass of Cu was prepared, heat-treated at 540 ° C., quenched in water and quenched. Next, the characteristics of the Al—Cu alloy wire were examined. It was confirmed that all Cu was present as a solid solution in Al. Further, when the natural potential was measured in seawater, it was -0.75 vs. SCE. Note that iron (hereinafter referred to as Fe) and silicon (hereinafter referred to as Si) inevitably present in the Al—Cu alloy wire were 0.25 mass% and 0.20 mass%, respectively. Next, an oxygen-free copper tape having a thickness of 0.4 mm is coated on the Al—Cu alloy wire by a Cu tape clad method to form a Cu-coated Al alloy wire, and then a single-head wire drawing machine and a continuous wire drawing machine are used. Using this, wire-drawing was performed up to Φ1.0 mm to obtain a Cu-coated Al composite wire. The end face of the Cu-coated Al composite wire was shaved with a precision cutter, subjected to a salt spray test in accordance with JIS standard Z2371, for 500 hours, and then the state of the end face was observed. Corrosion resistance was evaluated by measuring the erosion depth (mm) from the end face of the Al alloy core material. The results are shown in Table 1.

  Example 2 A rough drawn wire (Φ9.5 mm) of an Al alloy containing 4% by mass of Cu was prepared. This was heat-treated at 540 ° C. and then quenched in water and quenched. Next, the characteristics of the Al—Cu alloy wire were examined. It was confirmed that all Cu was present as a solid solution in Al. In addition, when the natural potential was measured in seawater, it was -0.69 vs. SCE. Note that Fe and Si unavoidably present in the Al—Cu alloy wire were 0.25 mass% and 0.20 mass%, respectively. Next, a Φ1.0 mm Cu-coated Al composite wire was prepared in the same manner as in Example 1, and similarly subjected to a salt spray test in accordance with JIS standard Z2371 for 500 hours, and then eroded from the end face of the Al alloy core material. The depth (mm) was measured to evaluate the corrosion resistance. The results are shown in Table 1.

  Comparative Example 1: A pure Al rough wire (Φ9.5 mm) was prepared, and the natural potential was measured in seawater, which was -0.83 vs. SCE. Next, a Φ1.0 mm Cu-coated Al composite wire was prepared in the same manner as in Example 1, and similarly a salt spray test based on JIS standard Z2371 was conducted for 500 hours, and then the erosion depth from the end face of the Al core material The thickness (mm) was measured to evaluate the corrosion resistance. The results are shown in Table 1.

Comparative Example 2: A rough drawn wire (Φ9.5 mm) of an Al alloy containing 5% by mass of Cu was prepared. This was heat-treated at 540 ° C. and then quenched in water and quenched. Next, the characteristics of the Al—Cu alloy wire were examined. It was confirmed that a part of Cu was precipitated in Al as a CuAl ₂ intermetallic compound. This is a solid solution limit of 5.7% by mass of Cu, but it was close to the solid solution limit, and it was found that the solution cannot be completely formed by quenching in water. Further, when the natural potential was measured in seawater, it was -0.70 vs. SCE. Note that Fe and Si unavoidably present in the Al—Cu alloy wire were 0.25 mass% and 0.20 mass%, respectively. Next, when a Φ1.0 mm Cu-coated Al composite wire was prepared in the same manner as in Example 1, a breakage occurred during the wire drawing. This is presumably due to the influence of the CuAl ₂ intermetallic compound present in Al. For this reason, the corrosion resistance was not evaluated.

  Comparative Example 3 A rough drawn wire (Φ9.5 mm) of an Al alloy containing 1% by mass of Cu was prepared. This was heat-treated at 540 ° C. and then quenched in water and quenched. Next, the characteristics of the Al—Cu alloy wire were examined. It was confirmed that all Cu was present as a solid solution in Al. Further, when the natural potential was measured in seawater, it was -0.80 vs. SCE. Note that Fe and Si unavoidably present in the Al—Cu alloy wire were 0.25 mass% and 0.20 mass%, respectively. Next, a Φ1.0 mm Cu-coated Al composite wire was prepared in the same manner as in Example 1, and similarly subjected to a salt spray test in accordance with JIS standard Z2371 for 500 hours, and then eroded from the end face of the Al alloy core material. The depth (mm) was measured to evaluate the corrosion resistance. The results are shown in Table 1.

As apparent from Examples 1 and 2 in Table 1, galvanic corrosion can be suppressed to a practical level by using an Al alloy wire having a Cu content of 2 to 4% by mass as the Al core material. I understand. That is, by setting the Cu content of the Al alloy wire to 2% by mass as in Example 1, the natural potential becomes −0.75 cv.SCE, which is higher than the natural potential of the pure Al wire −0.83 cv.SCE. It can be close to the natural potential, and the erosion depth can be suppressed to 7 mm, which is about half of pure Al. Further, as described in Example 2, when the Cu content of the Al alloy wire is 4% by mass, the natural potential becomes −0.69 cv.SCE, and the natural potential of the pure Al wire is −0.83 cv.SCE. However, it can be seen that the natural potential of Cu can be made closer, and the erosion depth is 4 mm, further improving the corrosion resistance.
On the other hand, as seen in Comparative Example 2, when the Cu content of the Al alloy wire exceeds 5% by mass, an intermetallic compound precipitates in the Al of Cu and Cu coating When drawing to an Al composite wire, the wire breaks and becomes impractical. Further, as in Comparative Example 3, when the Cu content is considerably lower than 1% by mass and 2% by mass, the effect of Cu addition is not exhibited so much and the erosion depth is 12 mm, which is practically the same as in the case of pure Al wire. It ’s not right. As can be seen from Comparative Example 1, in the Cu-coated Al composite wire having pure Al as the core material, erosion due to galvanic corrosion occurs considerably deeply.

  A Cu-coated Al composite wire using an Al—Cu alloy wire with a specified Cu content as a core material does not have the problem of galvanic corrosion that has occurred in a conventional Cu-coated Al composite wire with pure Al as a core material. Even if the Cu coating is manufactured thinly by the Cu plating method, it is excellent in corrosion resistance and can reduce the Cu coverage, so that it can cope with weight reduction and is practical as a Cu-coated Al composite wire.

Claims (2)

  A highly corrosion-resistant copper-coated aluminum composite wire, wherein a copper coating is provided on a core material of an aluminum alloy containing 2 to 4% by mass of copper.   The high corrosion resistance copper-coated aluminum composite wire according to claim 1, wherein the copper coating is formed by a plating method.