JP2010182537A - Aluminum-covered steel wire and overhead wire using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum-covered steel wire having high corrosion resistant characteristics in spite of use of aluminum having the same level of purity as that of usual aluminum for an overhead transmission line, and the overhead transmission line using it. <P>SOLUTION: As for the aluminum-covered steel wire 1, the outer circumference of a steel wire 10 is covered by aluminum, and it has an alumite layer 12 or a boehmite layer 13 which are corrosion-resistant layer on a surface of the aluminum-covered layer 11. Thickness of the alumite layer 12 is suitable within a range of 0.2 μm or more and 50 μm or less, and thickness of the boehmite layer 13 is suitable within a range of 0.2 μm or more and 5 μm or less. By forming a plurality of aluminum conductor wires 21 at the outer circumference of this aluminum-covered wire 1, the overhead transmission line 2 is obtained. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to an aluminum-coated steel wire (aluminum-covered steel wire) and an overhead electric wire using the same, and in particular, aluminum having high corrosion resistance while using aluminum having a purity equivalent to that of normal overhead power transmission aluminum. The present invention relates to a steel covered wire and an overhead electric wire using the same.

Conventionally, as overhead conductors, steel core aluminum stranded wires of the aluminum conductor wires on the outer periphery of the line from galvanized steel combined plurality of twisted (A luminum C onductor S teel R einforced: ACSR) is widely used. When such an electric wire is laid in a polluted area such as a coastal zone or an industrial zone, corrosion may occur due to sea salt particles or smoke gas existing in the surrounding environment. In recent years, it has also been pointed out that in areas other than these areas, as represented by acid rain, corrosion proceeds due to moisture containing fouling substances. If an electric wire corrodes, the mechanical performance and electrical performance will fall, and it will become difficult to supply electric power stably. Furthermore, when corrosion progresses, the electric wire may break and power transmission may become impossible.

  Conventionally, anti-corrosion grease has been applied as means for suppressing such corrosion of overhead electric wires. In other words, this method is to fill and apply grease-like anticorrosive agent between the strands of the overhead wires and the outer surface, and the corrosive substances such as sea salt particles and fouling gas components make up the wires and steel that make up the wires. It prevents contact with the wire and suppresses the progress of corrosion.

  Moreover, the overhead electric wire which uses high purity aluminum as a coating | covering material is proposed as what improves the corrosion resistance of an overhead electric wire (for example, refer patent document 1). According to the conventional overhead electric wire described in Patent Document 1, high purity aluminum having a purity of 99.9% or more that is excellent in corrosion resistance against fouling substances that cause corrosion is coated on a steel wire that is an anticorrosion object. Has been. Thereby, the overhead electric wire excellent in corrosion resistance is obtained.

  Furthermore, an overhead electric wire in which other elements are added to aluminum having a purity of 99.9% by weight or more has been proposed as a coating with corrosion resistance and mechanical strength (see, for example, Patent Document 2). According to the conventional overhead electric wire described in Patent Document 2, as a supplement to the mechanical strength of aluminum having a purity of 99.9% by weight or more, the total amount added is in the range of 0.03 to 0.3% by weight, An aluminum alloy to which any one or more of zirconium, manganese and magnesium is added is used as an aluminum conductor wire of a steel core aluminum wire (ACSR) or a coating material for a steel wire. Thus, an overhead electric wire excellent in corrosion resistance and mechanical strength can be obtained by replacing or covering the anticorrosion object with a high corrosion resistance and high strength material.

JP 2005-11570 A JP 2006-222021 A

However, the method of filling and applying the anticorrosion grease to the overhead electric wire has the following problems. That is,
(1) The electric wires installed outdoors are exposed to rain and wind, and the grease agent on the surface of the electric wires may peel off or flow down. In this case, the anticorrosive effect of the grease agent is not only reduced, but the grease agent that has flowed down may lead to contamination of the surrounding environment.
(2) In addition, there are cases in which the anti-corrosion effect has been reduced due to deterioration of the grease agent itself due to the influence of aging sunlight (ultraviolet irradiation) or the like.
(3) Furthermore, it has been pointed out that the workability at the time of laying construction of the electric wire filled and coated with the grease agent is slightly inferior to that of the normal electric wire not using the grease agent.
In addition, according to the conventional overhead electric wires described in Patent Documents 1 and 2, the use of high-purity aluminum having a purity of 99.9% by weight or more can improve the corrosion resistance, but the process required for refining aluminum and its manufacturing cost are large. Therefore, there is a problem that it leads to a significant cost increase of the entire overhead electric wire.

  Accordingly, an object of the present invention is to provide an aluminum-covered steel wire that has high corrosion resistance and is economical while using aluminum having the same purity as that of ordinary aluminum for overhead power transmission lines, and an overhead electric wire using the same. Is to provide.

  In order to achieve the above object, the present invention provides an aluminum-clad steel wire in which an aluminum coating layer is formed by coating the outer periphery of a steel wire, and the aluminum coating steel has a corrosion-resistant layer on the surface of the aluminum coating layer. Provide a line.

  As the corrosion resistant layer, an alumite layer or a boehmite layer is preferable. Moreover, it is preferable that the thickness of this alumite layer is 0.2 μm or more and 50 μm or less. The thickness of the boehmite layer is preferably 0.2 μm or more and 5 μm or less.

  In order to achieve the above object, the present invention has one or a plurality of the above-mentioned aluminum-covered steel wires and a plurality of aluminum conductor wires in the circumferential direction on the outer periphery of the aluminum-covered steel wires. Provide overhead power lines.

  According to the present invention, an aluminum-clad steel wire having high corrosion resistance and excellent economy while using aluminum having the same purity as that of normal overhead power transmission line aluminum and an overhead electric wire using the same Can be provided.

(A) is sectional drawing which showed the cross-sectional structure of the aluminum covering steel wire which provided the alumite layer which concerns on the 1st Embodiment of this invention, (b) is the aluminum covering steel which provided the boehmite layer It is sectional drawing which showed the cross-sectional structure of the line. It is sectional drawing which showed the cross-sectional structure of the overhead electric wire which concerns on the 2nd Embodiment of this invention.

  Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

[First Embodiment]
1 (a) and 1 (b), reference numeral 1 denotes an aluminum-coated steel wire according to the first embodiment of the present invention. The aluminum-coated steel wire 1 is an aluminum-coated steel wire in which a corrosion-resistant layer of an alumite layer having corrosion resistance or a corrosion-resistant layer of a boehmite layer is provided on the outer peripheral surface of the aluminum coating layer 11. In the following description, these aluminum-coated steel wires are simply referred to as “aluminum-covered steel wires”.

  The aluminum covered steel wire 1 includes a steel wire 10 made of a round wire, an aluminum covering layer 11 made of aluminum so as to cover the outer periphery of the steel wire 10, and an alumite layer provided on the outer peripheral surface of the aluminum covering layer 11. 12 or a boehmite layer 13. The thickness of the alumite layer 12 serving as the corrosion resistant layer is in the range of 0.2 μm to 50 μm, and the thickness of the boehmite layer 13 serving as the corrosion resistant layer is in the range of 0.2 μm to 5 μm. The aluminum-clad steel wire 1 can be used for a power transmission line, a distribution line, and the like, for example.

Although aluminum of the aluminum coating layer 11 belongs to a base class among practical metals, it is difficult to corrode in the atmosphere. This is because aluminum is immediately oxidized by oxygen in the atmosphere, and an extremely thin and dense oxide film (thickness of several tens of microns, on the order of 10 ⁻³ μm) is formed on the surface. For this reason, in order to increase the corrosion resistance of aluminum, it is effective to increase the surface film thickness by surface treatment such as alumite treatment or boehmite treatment. The excellent corrosion resistance of these films has been reported in many literatures such as the Japan Light Metal Association, “Aluminum Handbook” 1963, Asakura Shoten, p824-829, p1265-1267.

  The alumite layer 12 having excellent corrosion resistance can be obtained by applying an electric current with aluminum as an anode in a specific electrolytic solution. When the thickness of the alumite layer 12 is less than 0.2 μm, the film thickness is thin and sufficient corrosion resistance cannot be obtained. On the other hand, when the thickness of the anodized layer 12 exceeds 50 μm, it takes a long time to form the anodized layer 12 (electrolytic time), leading to an increase in manufacturing cost. Accordingly, the thickness of the alumite layer 12 is preferably in the range of 0.2 μm to 50 μm.

  On the other hand, the boehmite layer 13 having excellent corrosion resistance can be obtained by steaming with high-pressure steam or boiling in water. When the thickness of the boehmite layer 13 is less than 0.2 μm, the film thickness is thin and the corrosion resistance is insufficient. In addition, when the thickness of the boehmite layer 13 exceeds 5 μm, it takes a long time to form the boehmite layer 13 (boehmite treatment time), resulting in a problem that the manufacturing cost increases. Accordingly, the thickness of the boehmite layer 13 is preferably in the range of 0.2 μm to 5 μm.

  Moreover, as an electrolyte solution at the time of forming the alumite layer 12, various compositions such as a sulfuric acid-based solution, an oxalic acid-based solution, and a chromic acid-based solution can be mentioned, and can be arbitrarily selected. In forming the boehmite layer 13, there are no particular restrictions on the manufacturing method, additive substances, etc., and the processing conditions of the prior art can be arbitrarily selected.

[Effect of the first embodiment]
According to the first embodiment described above, in the aluminum-clad steel wire 1 in which the aluminum coating layer 11 is formed by coating the outer circumference of the steel wire 10, the thickness 0 having corrosion resistance on the outer circumferential surface of the aluminum coating layer 11. Since the corrosion resistant layer of the alumite layer 12 having a thickness of 2 μm or more and 50 μm or less or the corrosion resistant layer of the boehmite layer 13 having a thickness of 0.2 μm or more and 5 μm or less is provided, aluminum having the same purity as that of ordinary overhead transmission line aluminum is used. However, since it has high corrosion resistance and can omit the aluminum purification process (refining) for improving the corrosion resistance, excellent economic efficiency can be imparted.

  Moreover, by providing a corrosion-resistant layer, it is possible to suppress the progress of corrosion due to corrosive substances such as sea salt particles and fouling substances, and the aluminum-clad steel wire of the present invention that constitutes the overhead electric wire is due to contact with the aluminum conductor wire. It is possible to suppress the corrosion promoting action (dissimilar metal contact corrosion, electrolytic corrosion) of the aluminum conductor wire based on the potential difference between steel and aluminum.

[Second Embodiment]
Referring to FIG. 2, an aerial wire according to a second embodiment of the present invention is shown. The overhead electric wire 2 includes the aluminum-covered steel wire 1 described in the first embodiment, six aluminum-covered steel wires 1 twisted in the circumferential direction on the outer periphery of one aluminum-covered steel wire 1, and 7 12 aluminum conductor wires 21 twisted in the circumferential direction on the outer periphery of the two aluminum-clad steel wires 1, and 18 aluminum conductor wires 21 twisted further in the circumferential direction on the outer periphery of the 12 aluminum conductor wires 21; have. Seven aluminum-clad steel wires 1 function as tension members. The aluminum conductor wire 21 is made of pure electrical aluminum (purity of about 99.7% by weight).

[Effect of the second embodiment]
According to the second embodiment described above, the corrosion resistant layer of the alumite layer 12 having a thickness of 0.2 μm or more and 50 μm or less, or the thickness on the outer peripheral surface of the aluminum coating layer 11 of the aluminum covered steel wire 1 constituting the tension member. Since the corrosion resistant layer of the boehmite layer 13 having a thickness of 0.2 μm or more and 5 μm or less is provided, in addition to the preferable effect described in the first embodiment, the exposure of the steel wire 10 due to the improvement of the corrosion resistance of the tension member can be prevented.

  When the steel ground of the steel wire 10 is exposed due to the corrosion of the aluminum coating layer 11 and comes into contact with the adjacent aluminum conductor wire 21, the corrosion promotion action of the aluminum conductor wire based on the potential difference between the steel and aluminum (dissimilar metal contact corrosion, electrolytic corrosion) ) Occurs, and the corrosion products generated at that time promote the surrounding corrosion. However, in this second embodiment, the dissimilar metal contact corrosion (electric corrosion) of the aluminum conductor wire 21 due to the exposure of the steel wire 10 of the aluminum-clad steel wire 1 is extremely difficult to act, and the corrosion. Since the production amount of the product is also very small, the corrosion of the entire overhead wire 2 is suppressed, and the mechanical strength and electrical performance of the overhead wire 2 are maintained over a long period of time.

  In addition, by improving the corrosion resistance and securing the mechanical strength and electrical performance of the electric wires, it is possible to supply stable power and extend the period of use, thereby reducing the operating cost of power transmission equipment. It becomes. Furthermore, a serious accident can be prevented in advance.

  Hereinafter, more specific examples of the present invention will be described together with comparative examples and conventional examples. First, the Example of the aluminum covered steel wire 1 is demonstrated.

  As Example 1, iron (Fe) 0.20% by weight, silicon (Si) 0.07% by weight, copper (cu) 0.003% by weight, titanium (Ti) 0.002% by weight, vanadium (V) 0 A cast material was produced using an aluminum ingot having a purity of about 99.7% by weight, and the balance was made of aluminum (Al). The cast material was subjected to a hot rolling process and had a strand diameter of 9.5 mm. An aluminum rough wire was obtained. Next, the steel wire was coated with aluminum using this rough drawn wire by a hot extrusion method. Then, the obtained composite wire was cold-drawn with a single-head wire drawing machine under conditions of 1-pass reduction 25 ± 5% and a drawing speed of 20 m / min, and the strand diameter was 2.6 mm and the aluminum coating thickness was 0. A 17 mm aluminum covered steel wire was obtained. After this aluminum-clad steel wire was sandblasted, a direct current was applied as an anode in an oxalic acid-based solution. At this time, aluminum-clad steel wire 1 (Examples 1-1, 1-2, and 1-3 shown in Table 1) having current application time as parameters and anodized layer thicknesses of 0.2, 8, 29, and 50 μm, respectively. And 1-4).

  As Example 2, a cast material was produced using an aluminum ingot having the same composition and the same weight% as in Example 1 and having a purity of about 99.7% by weight, and a hot rolling process was performed under the same conditions as in Example 1. The aluminum rough wire obtained by the above was coated with aluminum on the steel wire by hot extrusion and cold-drawn to obtain an aluminum-clad steel wire having the same wire diameter and the same aluminum coating thickness as in Example 1. . This aluminum-clad steel wire was sandblasted and then immersed in 90 ° C. pure water for boehmite treatment. At this time, the aluminum-clad steel wire 1 having the immersion time as a parameter and the boehmite layer thicknesses of 0.2, 1.4, 3.5, and 5 μm, respectively (Examples 2-1 and 2-2 shown in Table 1, 2-3 and 2-4) were obtained.

Comparative Example 1

  Further, as Comparative Example 1 of the aluminum-clad steel wire, a cast material was produced using an aluminum metal having the same composition and the same weight% as in Example 1 and having a purity of about 99.7% by weight. Under the conditions, the aluminum rough wire obtained by the hot rolling process was coated with aluminum on the steel wire by the hot extrusion method and cold-drawn, and the same wire diameter and the same aluminum coating thickness as in Example 1 were applied. An aluminum covered steel wire was obtained. After this aluminum-clad steel wire was sandblasted, a direct current was applied in a solution having the same composition as in Example 1, and the aluminum-clad steel wires having alumite layer thicknesses of 0.1 μm, 55 μm, and 82 μm (comparison shown in Table 1) Examples 1-1, 1-2 and 1-3) were obtained.

Comparative Example 2

  As Comparative Example 2 of the aluminum-clad steel wire, a cast material was produced using an aluminum ingot having the same composition and the same weight% as in Example 1 and having a purity of about 99.7% by weight. Then, the aluminum wire drawn by the hot rolling process was coated on the steel wire by the hot extrusion method and cold-drawn to cover the aluminum wire with the same wire diameter and the same aluminum coating thickness as in Example 1. A steel wire was obtained. This aluminum-clad steel wire was sandblasted and then subjected to boehmite treatment at the same temperature and in the same solution as in Example 2, and the aluminum-clad steel wires having a boehmite layer thickness of 0.1 μm, 5.9 μm, and 7.7 μm (table Comparative Examples 2-1, 2-2, and 2-3) shown in FIG.

Conventional Example 1

  Further, as a conventional example 1 of an aluminum-clad steel wire, a cast material was produced using an aluminum ingot having a purity of about 99.7% by weight and the same composition as in Example 1, and the same as in Example 1. Under the conditions, the aluminum rough wire obtained by the hot rolling process was coated with aluminum on the steel wire by the hot extrusion method and cold-drawn, and the same wire diameter and the same aluminum coating thickness as in Example 1 were applied. An aluminum-clad steel wire (conventional example 1 shown in Table 1) was obtained.

  Aluminum covered steel wire 1 of Examples 1-1 to 1-4 and 2-1 to 2-4 described above, Comparative examples 1-1 to 1-3, 2-1 to 2-3, and aluminum covered of conventional example 1 In addition to investigating the corrosion resistance of steel wires through accelerated corrosion experiments, we evaluated the economic efficiency from the viewpoint of film formation time and performed a comprehensive evaluation. In the corrosion acceleration experiment, an aluminum-clad steel wire cut to a length of 500 mm was immersed in a hydrogen chloride aqueous solution at pH 2 for 50 hours, and the corrosion progress of each was evaluated relatively. Table 1 shows the performance evaluation results of various aluminum-clad steel wires.

  As is clear from Table 1, in the aluminum-clad steel wires 1 of Examples 1-1 to 1-4 and 2-1 to 2-4, corrosion progress is suppressed as compared with Conventional Example 1, and corrosion resistance is improved. Was good. In particular, in Examples 1-2, 1-3, 1-4, and 2-3, 2-4, the degree of progress of corrosion was extremely small and had excellent corrosion resistance. Moreover, the thing of the corrosion-resistant layer which consists of different film thicknesses of Examples 1-1 to 1-4 and 2-1 to 2-4 has a problem in actual production because the film formation time is short and good. It is in a level that does not become, and is good from the point of economical efficiency. In this way, the outer periphery of the steel wire 10 is coated with electrical pure aluminum having the same purity as that of ordinary overhead power transmission line aluminum to form the aluminum coating layer 11, and the outer peripheral surface of the corrosion-resistant alumite layer 12, Alternatively, it is possible to obtain the aluminum-clad steel wire 1 having excellent corrosion resistance and economy by forming the boehmite layer 13 with a thickness within a specified range.

  On the other hand, for the aluminum-clad steel wires of Comparative Examples 1-1, 1-2, 1-3 and 2-1, 2-2, 2-3 in which the thickness of the corrosion-resistant layer is out of the specified range, If the film thickness is small, sufficient corrosion resistance cannot be obtained, and if the film thickness of the corrosion-resistant layer increases, the corrosion resistance will be good, but the film formation time will be long, so it is inferior from the economical point of view. (This leads to an increase in the cost of the product).

  Next, an embodiment of the overhead electric wire 2 of the present invention will be described.

Six aluminum covered steel wires 1 are twisted around the φ2.6 mm aluminum covered steel wire 1 having the anodized layer obtained in Example 1 above, and an electrical pure having a purity of about 99.7% by weight around the aluminum covered steel wire 1. aluminum conductor wires made of aluminum (Fai2.6Mm) 21 to 12, further combined the aluminum conductor wires 21 18-ply therearound, carried illustrated in overhead conductors 2 (Table 2 conductor effective area 160 mm ² Example 3- 1, 3-2, 3-3 and 3-4) were prepared.

Six aluminum covered steel wires 1 are twisted around the φ2.6 mm aluminum covered steel wire 1 having the boehmite layer obtained in Example 2 above, and an electrical pure having a purity of about 99.7% by weight around the aluminum covered steel wire 1. aluminum conductor wires made of aluminum (Fai2.6Mm) 21 to 12, further combined the aluminum conductor wires 21 18-ply therearound, carried illustrated in overhead conductors 2 (Table 2 conductor effective area 160 mm ² Example 4 - 1, 4-2, 4-3 and 4-4) were prepared.

Comparative Example 3

Six aluminum-clad steel wires are twisted around the φ2.6 mm aluminum-clad steel wire having the alumite layer obtained in Comparative Example 1, and pure aluminum for electrical use having a purity of about 99.7% by weight is wound around the aluminum-clad steel wire. 12 aluminum conductor wires (φ2.6 mm), and 18 aluminum conductor wires twisted around the aluminum conductor wires (overhead wires having an effective conductor cross-sectional area of 160 mm ² (Comparative Examples 3-1 and 3-2 shown in Table 2) And 3-3).

Comparative Example 4

Six aluminum-coated steel wires are twisted around the φ2.6 mm aluminum-coated steel wire having the boehmite layer obtained in Comparative Example 2 above, and pure aluminum for electrical use having a purity of about 99.7% by weight is formed around the wire. 12 aluminum conductor wires (φ2.6 mm), and 18 aluminum conductor wires twisted around the aluminum conductor wires (overhead wires having an effective conductor cross-sectional area of 160 mm ² (Comparative Examples 4-1 and 4-2 shown in Table 2) And 4-3).

Conventional example 2

In addition, as conventional example 2 of the overhead electric wire, six aluminum covered steel wires are arranged around the φ2.6 mm aluminum covered steel wire obtained in the above conventional example 1 of the aluminum covered steel wire having no anodized layer or boehmite layer. Twisted, 12 aluminum conductor wires (φ2.6mm) made of pure aluminum for electrical use with a purity of about 99.7% by weight are twisted around it, and 18 aluminum conductor wires are twisted around it to obtain an effective conductor cross-sectional area. A 160 mm ² overhead electric wire (conventional example 2 shown in Table 2) was produced.

Conventional example 3

In addition, as conventional example 3 of the overhead electric wire, six same hot-dip galvanized steel wires are twisted around a φ2.6 mm hot-dip galvanized steel wire, and pure aluminum for electrical use having a purity of about 99.7% by weight is wound around the wire. 12 aluminum conductor wires (φ2.6 mm) and 18 aluminum conductor wires were twisted around the aluminum conductor wires to produce an overhead electric wire (conventional example 3 shown in Table 2) having a conductor effective cross-sectional area of 160 mm ² .

  About the overhead electric wire 2 of the said Examples 3-1 to 3-4 and 4-1 to 4-4, the comparative examples 3-1 to 3-3, 4-1 to 4-3, and the overhead wires of the conventional examples 2 and 3 The corrosion resistance was examined by an accelerated corrosion experiment and evaluated together with the economic efficiency shown in Table 1. In the corrosion acceleration experiment, an overhead electric wire was installed horizontally, and sulfuric acid was added to a 3% by weight sodium chloride aqueous solution to adjust the pH to 3 under the condition of energizing with a transformer so that the wire temperature was 90 ° C. The electrolyte solution was sprayed for 1 hour and air-dried for 2 hours as one cycle, and this was repeated. As a result of the performance evaluation of various overhead electric wires, the corrosion progress of 6-layer aluminum-clad steel wire and hot-dip galvanized steel wire after 6000 cycles of corrosion experiments, and electro-corrosion on 12-layer aluminum conductor wire in contact with this ( Table 2 shows the results of investigation on the situation of dissimilar metal contact corrosion.

  As is apparent from Table 2, the overhead electric wire using the galvanized steel wire of Conventional Example 3 is corroded as compared with the overhead electric wires 2 of Examples 3-1 to 3-4 and 4-1 to 4-4. In the 6-layer steel wire, the galvanized layer disappears over the entire area and the steel ground is exposed, and the inner 12-layer aluminum conductor wire in contact with the steel wire and the outer layer located outside thereof In the 18-layer aluminum conductor wire, wire breakage due to corrosion frequently occurred. It is suggested that the corrosion of the overhead electric wire is largely controlled by the steel ground exposure of the steel wire.

  Moreover, in the overhead electric wires 2 of Examples 3-1 to 3-4 and 4-1 to 4-4, any steel ground exposure of the aluminum-covered steel wire 1 is not recognized, and the steel wire 12 is in contact with the steel wire. In the aluminum conductor wire 21 of this layer, no significant corrosion due to electrolytic corrosion was observed. In this way, a corrosion-resistant layer is formed on the outer peripheral surface of the alumite layer 12 or the boehmite layer 13 with a thickness within a specified range with respect to the pure aluminum conductor wire 21 having a purity of about 99.7% by weight for the overhead electric wire 2. By using the aluminum-clad steel wire 1 having the aluminum coating layer 11, the entire overhead electric wire 2 can be made highly corrosion resistant.

  On the other hand, for Comparative Examples 3-1, 3-2, 3-3 and 4-1, 4-2, 4-3 in which the thickness of the corrosion resistant layer is out of the specified range, the corrosion resistant layer in the aluminum-clad steel wire is used. When the film thickness is small, the corrosion resistance is insufficient, and the steel ground exposure of the aluminum-clad steel wire and the accompanying corrosion progress of the aluminum conductor wire are observed. Further, although the corrosion resistance is improved as the film thickness is increased, as described above, the economical efficiency is greatly reduced due to the longer film formation time.

  In the present embodiment, the case where the composition of the aluminum coating layer in the aluminum-clad steel wire is pure aluminum for electrical use has been described, but the same effect can be obtained also in other compositions, for example, an aluminum-clad steel wire using an aluminum alloy. .

  In the present embodiment, the case where the wire shape of the aluminum-clad steel wire and the overhead electric wire is a round wire (circular cross-sectional shape) has been described, but aluminum having other cross-sectional shapes such as a forming wire (atypical wire). Similar effects can be obtained with steel-clad wires and overhead wires.

  Furthermore, in this embodiment, an aluminum-clad steel wire having an alumite layer or a boehmite layer with a corrosion-resistant layer formed on the entire outer peripheral surface of the aluminum coating layer has been described, but a plurality of aluminum-clad steel wires are twisted together to form a stranded wire. By providing an alumite layer and a boehmite layer as a corrosion-resistant layer after that, a film is formed only at a location in contact with the inner layer aluminum conductor wire of the overhead electric wire. Therefore, there is an electrolytic corrosion suppressing effect between the aluminum covered steel wire and the aluminum conductor wire 21, and as a result, the corrosion resistance of the entire overhead electric wire can be improved.

  Further, in this embodiment, the corrosion-resistant layer is not applied to the aluminum conductor wire, but the corrosion resistance of the overhead electric wire can be further improved by forming the corrosion-resistant layer similarly to the aluminum-covered steel wire.

  In this embodiment, the case of an aluminum-covered steel core aluminum strand (ACSR / AC) using a pure aluminum wire for electrical use having a purity of about 99.7% by weight as the conductor of the aluminum conductor wire has been described. It goes without saying that the effect obtained does not change even if the type of the electric wire is different, such as an aluminum-coated steel core heat-resistant aluminum alloy wire (TACSR / AC) using an alloy wire.

  Moreover, the same corrosion-resistant effect is acquired also about the overhead ground wire to which the aluminum covered steel wire of this invention is applied.

DESCRIPTION OF SYMBOLS 1 Aluminum covered steel wire 2 Overhead electric wire 10 Steel wire 11 Aluminum coating layer 12 Anodized layer 13 Boehmite layer 21 Aluminum conductor wire

Claims (5)

  An aluminum-covered steel wire in which an outer periphery of the steel wire is coated to form an aluminum coating layer, wherein the aluminum-coated steel wire has a corrosion-resistant layer on the surface of the aluminum coating layer.   The said corrosion-resistant layer consists of an alumite layer or a boehmite layer, The aluminum covered steel wire characterized by the above-mentioned.   The aluminum-clad steel wire according to claim 2, wherein the alumite layer has a thickness of 0.2 µm or more and 50 µm or less.   The aluminum-clad steel wire according to claim 2, wherein the boehmite layer has a thickness of 0.2 µm or more and 5 µm or less.   It has one or a plurality of said aluminum covered steel wires according to any one of claims 1 to 4, and a plurality of aluminum conductor wires in a circumferential direction on an outer periphery of said aluminum covered steel wires. An overhead electric wire to be used.

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