JP2000308432A - Anticorrosion-treated marine structure made of copper or copper alloy and corrosion-preventing method for marine structure made of copper or copper alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a marine structure made of copper or copper alloy that suitably dissolves copper ion in the sea water throughout the season in any place to inhibit algae, shells and other organisms from fouling, and has a long life with excellent durability, and provide a corrosion-preventing method for the marine structure made of copper or copper alloy. SOLUTION: This marine structure made of copper or copper alloy 1 is electrically connected with a connecting means 7 via an adjustment 6 to a different metal 5 baser than the copper or the copper alloy provided in the vicinity of a draft part of the marine structure 1. The potential difference between the copper or the copper alloy wire net 10 constituting the copper or the copper alloy marine structure 1 and the different baser metal 5 are adjusted with the adjustment 6 to control the level of the corrosion of the copper or the copper alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aquaculture cage composed of, for example, a wire mesh of copper or copper alloy wire, a copper or copper alloy tube for taking in and draining cooling water for a nuclear power plant, and copper or copper attached thereto. The present invention relates to an underwater structure made of copper or a copper alloy in which corrosion prevention of an alloy screen is performed, and a method of preventing corrosion of an underwater structure made of copper or a copper alloy.

[0002]

2. Description of the Related Art For example, in a fish cage for aquaculture, a fish net cage made of synthetic fiber has been conventionally used. However, this has a problem that algae and shellfish easily adhere to the net, the mesh is closed, oxygen is not sufficiently supplied to the cage, and the cultured fish causes oxygen deficiency.

[0003] For this reason, fishing nets are generally landed and washed, and at the same time, they are used by dipping and applying an antifouling agent to the fishing nets. Therefore, cost and labor are required for the regular landing, cleaning and application of the antifouling agent. Some of these antifouling agents pose problems of persistence in cultured fish and marine pollution, and have been strictly regulated in recent years.

[0004]

To solve these problems at once, the present applicant has been experimenting with a cage made of a wire mesh of copper or copper alloy wire. The copper or copper alloy cage prevents the adhesion of algae and shellfish by a trace metal action of copper (corrosion of copper, ie, an antibacterial action by elution of ions). Therefore, regular landing, washing and application of an antifouling agent as in the prior art are not required, and the mesh of the wire mesh is not blocked, and oxygen is sufficiently supplied to the inside of the cage.

However, copper or copper alloy has excellent corrosion resistance in seawater among metals,
In proceeding with the experiment, the copper alloy wire is 0.5 to 0.6m in half a year at the draft, especially at the draft of the corner of the square shaped cage.
It was found that there was a problem that the corrosion was severely reduced to m, the wire diameter of the portion was thinned, the strength was reduced, and the durability as a cage was deteriorated, that is, the life was shortened. It is considered that this is because a local battery is formed by oxygen concentration at the draft part, and the local current caused by this is concentrated at the corner of the ponds. And the maximum corrosion part is 50-60mm from the draft part.
And the area subject to local corrosion is 3
It is within 00 mm.

[0006] Attempts have been made to prevent corrosion of copper or copper alloys by utilizing a galvanic anode method, which is a general anticorrosion method. However, in the case of underwater structures made of copper or copper alloy used in the ocean, such as fish cages for aquaculture, the corroded part of the copper or copper alloy wire mesh is near the draft and the galvanic anode method is used. In this case, the installation place of the anode is limited. For this reason, the anticorrosive effect is so great that the trace metal effect of copper is lost and algae and shellfish are attached, or conversely, there is not much anticorrosive effect and algae and shellfish are attached. In other words, the galvanic anode method is applied to underwater structures made of copper or copper alloy such as fish cages to control the potential difference between the sacrificial anode and the structure to be protected, and the trace metal action of copper and the galvanic anode method It was difficult to make use of both properties of copper, such as anticorrosive action.

[0007] Further, the ease with which algae and shellfish are attached greatly varies depending on the season, place, and tide. Thus, for example,
Even in the summer when algae and shellfish are easy to adhere, even if the corrosion prevention degree can be set so as to prevent the algae and shellfish from adhering, copper ions will be eluted more than necessary in winter when it is difficult to adhere,
Corrosion causes a problem such that the copper wire diameter becomes thinner, the strength is lowered, and the durability is deteriorated, that is, the life is shortened. Conversely, if the anticorrosion degree is set to be suitable for winter, algae and shellfish will adhere in summer.

The present invention has been made in order to solve the above-mentioned problems. The copper ions are appropriately eluted regardless of the season and place, algae and shellfish are not attached, and a long life with excellent durability is provided. It is an object of the present invention to provide a copper or copper alloy underwater structure and a method of preventing corrosion of copper or copper alloy underwater structures.

[0009]

According to a first aspect of the present invention, there is provided an underwater structure made of copper or a copper alloy and having a draft portion, and Provided in the vicinity, a dissimilar metal lower than the copper or copper alloy,
Corrosion-resistant copper comprising: connecting means for electrically connecting the dissimilar metal and the structure; and adjusting means provided on the connecting means for adjusting a potential difference between the dissimilar metal and the structure. Or a copper alloy underwater structure.

[0010] The copper or copper alloy submarine structure is connected to the underwater structure made of copper or copper alloy at a portion which is easily affected by waves, such as the shape of the submarine structure made of copper or copper alloy and the tidal current at the installation site, especially near the draft. The dissimilar metal lower than copper or copper alloy provided in the vicinity of the portion is electrically connected by the connecting means via the adjusting means. This makes it possible to adjust the potential of the copper or copper alloy underwater structure in the sea. Here, any means such as a cable and a coated iron can be used as the connection means. Further, as an adjusting means for adjusting the potential difference between the dissimilar metal and the structure, a variable resistor, a thermostat, an IC circuit, or the like that can adjust the potential difference between the dissimilar metal and the structure is used. For example, there is no particular limitation, and by using these, it is possible to adjust the potential difference between the two remotely or automatically.

Here, the dissimilar metal lower than copper or copper alloy is a metal that is more easily ionized than copper or copper alloy. For example, dissimilar metals lower than copper include magnesium, aluminum, and zinc. , Iron, nickel, tin and the like and alloys thereof. Among them, it is preferable to use an aluminum alloy in consideration of excellent economy, seawater resistance, environmental preservation, and the like.

[0012] The invention of claim 2 is a square-shaped aquaculture cage in which the underwater structure is formed of a wire mesh of copper or a copper alloy wire, wherein the dissimilar metal is placed in the vicinity of the square corner. The corrosion-resistant copper or copper alloy underwater structure according to claim 1, wherein:

[0013] By installing a dissimilar metal base to copper in a portion of the fish cage for aquaculture that is susceptible to the waves, particularly in the corner portion, it is possible to adjust the degree of corrosion in the corner portion which is susceptible to corrosion. Become.

Further, the invention according to claim 3 is characterized in that a dissimilar metal lower than copper or copper alloy is immersed in the vicinity of the draft portion of the underwater structure which is made of copper or copper alloy and has a draft portion, Electrically connecting the dissimilar metal and the submarine structure via potential difference adjusting means, and adjusting the potential of the draft portion of the submarine structure by 50 to 200 mV lower than the natural potential of the copper or copper alloy. This is a method for preventing corrosion of underwater structures made of copper or copper alloys.

The natural potential of copper in seawater is about -250.
50 to 200 mV, preferably 100 to 15 mV
Decrease by 0 mV. That is, about -300 to -450 m
V, preferably -350 to -400 mV. This makes it possible to adjust the degree of copper corrosion. In this specification, the natural potential and the value of the potential of copper in seawater refer to a potential difference between copper in seawater and a silver chloride electrode in seawater.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to FIGS. The embodiments of the present invention are not limited to the following examples.

FIG. 1 shows a rectangular cage for cultivating fish according to the present invention. FIG. 2 is a front view of a corner portion. In the figure, 1 is a cage, 2 is an inner frame, 3 is an outer frame,
4 is a float, 5 is a metal lower than copper serving as a sacrificial anode,
6 is an adjusting means, 7 is a connecting means, and 10 is a wire mesh made of copper or copper alloy wire.

The inner frame 2 and the outer frame 3 are frame structures in which lightweight square members, plates, pipes, and the like made of metal or wood are assembled in a rectangular frame shape. It is preferable that an anticorrosive is applied to the surface of the metal to prevent corrosion. The inner frame 2 and the outer frame 3 also serve as a scaffold for aquaculture workers to perform work. The inner frame 2 is provided with a net attaching portion for attaching the upper end of the wire net 10 made of copper or a copper alloy wire.

The float 4 is, as shown in the figure,
It is located between the inner frame 2 and the outer frame 3 and has a rectangular ring shape along the outer peripheral surface of the upper end of the wire mesh 10 made of copper or copper alloy wire, and is attached at equal intervals.

The wire net 10 made of copper or copper alloy wire is braided by a net making machine (metal netting machine) used for manufacturing an iron net. And, it has a rectangular cylindrical shape whose upper end is attached to a net attaching portion provided on the inner peripheral portion of the inner frame 2 by a wire rope or the like.

Each wire constituting the wire mesh 10 has a diameter of 3
４4 mm, and there are various copper or copper alloys, but considering corrosion resistance, copper 62.0 to 69.0% by weight
0.2 to 1.0% by weight of tin and 0.1 to 0.1% by weight of nickel
A seawater-resistant copper alloy containing at least one element of 1.0% by weight and having a metal composition composed of zinc and unavoidable impurities in the balance is preferable.

The dissimilar metal 5 (hereinafter, referred to as a sacrificial anode), which is lower than copper serving as a sacrificial anode, is made of magnesium, aluminum, zinc, iron, nickel, tin, etc. and their alloys as described above, It is preferable to use an aluminum alloy in consideration of seawater resistance and the like. It is preferable that the aluminum alloy is processed into a plate shape, a rod shape, or the like having a length of 300 to 500 mm before use. As shown in FIG. 2, the sacrificial anode 5 is provided on the outer frame 3 by an arbitrary method such as a rope or a wire rope.
(50-90 cm, preferably 60-80 cm), and attached so that the upper end thereof comes to the draft.

The sacrificial anode 5 is connected by the connecting means 7.
Wire mesh 1 made of copper or copper alloy wire via adjusting means 6
0 is electrically connected.

The connecting means 7 preferably uses a copper cable. The connecting means 7 is extended from a wire mesh 10 made of copper or copper alloy wire, connected to the adjusting means 6, and connected between the adjusting means 6 and the sacrificial anode 5.

As long as the connection means 7 can be connected to the sacrificial anode 5, the adjustment means 6, and the wire mesh 10 made of copper or copper alloy wire, other than the cable, for example, iron or the like can be used. Form, material, etc. are particularly limited as long as they are formed of a conductive material, and the surface thereof is coated with a coating for corrosion prevention, or a coating layer of plastic or the like is formed. Not something.

The adjusting means 6 is not particularly limited as long as it can adjust the potential difference between the sacrificial anode 5 and the wire mesh 10 made of copper or copper alloy wire, and the resistance can be artificially changed. Variable resistance can be exemplified. Adjusting means 6
Is housed in a waterproof housing and attached to either the inner frame 2 or the outer frame 3. By adjusting the resistance of the adjusting means 6, a wire mesh 10 made of copper or a copper alloy wire is formed.
And the potential difference between the sacrificial anode 5 and the metal mesh 10 made of copper or copper alloy wire can be adjusted. In addition, by using the sacrificial anode 5 having a length of 300 to 500 mm, the degree of corrosion of a portion that is susceptible to local corrosion can be adjusted.

In addition to the variable resistor, the adjusting means 6 includes a thermostat capable of changing the resistance depending on temperature, an IC circuit capable of automatically changing the resistance between the two devices based on the amount of current, and the like. Can be illustrated. By using these, the potential difference between the sacrificial anode 5 and the wire mesh 10 made of copper or copper alloy wire can be controlled manually, automatically, or remotely, so that copper ions are always eluted appropriately. , The degree of copper corrosion can be adjusted.

[0028]

The present invention will be described in more detail with reference to the following examples.

(Example 1) Copper alloy wire having a diameter of 3.0 mm (copper: 64.0%, zinc: 35.1%, tin: 0.6%, nickel: 0.3%, manufactured by Sanbo Copper Alloy Co., Ltd., trade name) UR30
According to W), a wire mesh having a mesh size of 32 mm was produced, and
It was finished as a cage with a size of mx 10m x 8m in depth and installed in the sea of Kosasa town, Nagasaki prefecture for 6 months from May to November. In addition,
The natural potential of the copper alloy wire in the ocean is -253 to -2
It is 56 mV (measured with a seawater silver chloride electrode using a digital CP checker manufactured by Nihon Corrosion Industry Co., Ltd.) At the corner of this cage made of wire mesh (see Fig. 1),
An aluminum alloy rod weighing 6.5 kg was placed 70% from the pond.
The copper alloy wire and the aluminum alloy rod are electrically connected to each other through a variable resistor at a position of 1 cm from the draft part. And the potential of the copper alloy wire is -272 m by the variable resistor.
V, the algae adhesion state at the corner after 6 months had elapsed and the maximum diameter reduction of the copper alloy wire were measured, and the distance from the draft where the maximum diameter reduction occurred was examined. When the resistance of the variable resistor is increased, the potential of the wire net 10 is increased.

(Embodiment 2) An aluminum alloy rod was installed at the corner of a living cage (see FIG. 1) in the same manner as in Embodiment 1,
Same as Example 1 except that the potential of the copper alloy wire was -326 mV.

(Embodiment 3) An aluminum alloy rod was installed at the corner of a living cage (see FIG. 1) in the same manner as in Embodiment 1,
Same as Example 1 except that the potential of the copper alloy wire was -384 mV.

(Embodiment 4) An aluminum alloy rod was installed at the corner of a living cage (see FIG. 1) in the same manner as in Embodiment 1,
Same as Example 1 except that the potential of the copper alloy wire was -435 mV.

Table 1 summarizes the above results.

[0034]

[Table 1]

As can be seen from Table 1, if the variable resistance is set to be 50 to 200 mV lower than the natural potential of copper in the sea, no algae will adhere remarkably and the amount of corrosion of the copper alloy wire will be minimized. Can be suppressed. By setting the potential of copper within the above range, it is possible to effectively utilize the antibacterial action of copper without completely preventing corrosion of copper. In addition, the life of the aluminum alloy rod itself can be extended by adjusting the potential difference by the variable resistance. In consideration of the life of the aluminum alloy rod, it is preferable to set the aluminum alloy rod 100 to 150 mV lower than the natural potential.

[0036]

According to the first aspect of the present invention, a copper or copper alloy underwater structure and a dissimilar metal lower than copper or copper alloy provided near the draft portion thereof are adjusted. By electrically connecting the submerged structures and appropriately setting the potential difference therebetween, the degree of corrosion can be adjusted without completely preventing the underwater structure made of copper or copper alloy. Further, by this adjusting means, the potential difference between the two can be adjusted to an appropriate potential difference by manual, automatic or remote control. Therefore, the algae and shellfish do not adhere to the copper or copper alloy submarine structure, and the local corrosion of the copper or copper alloy submarine structure draft can be minimized, and the durability is excellent. Becomes In summer, when the algae and shellfish are likely to adhere, the potential difference between the two is adjusted to a higher level, and copper or copper alloy is slightly corroded (eluted) to prevent the algae and shellfish from attaching. In addition, the potential difference is adjusted to be lower in winter when the algae and shellfish are hard to adhere and the waves are rough, so that corrosion of copper or copper alloy can be prevented.

Further, according to the second aspect of the present invention, copper can be slightly corroded and copper ions can be eluted without completely preventing corrosion of the draft portion and the corner of the pond. As a result, algae and shellfish do not adhere to the corner of the cage, local corrosion of the draft portion at the corner of the cage can be minimized, and a long-life cage with excellent durability can be obtained. In addition, dissimilar metals that are lower than copper or copper alloy serving as a sacrificial anode for adjusting the degree of corrosion of the wire mesh made of copper or copper alloy at the corner of the pond, if it is installed in advance in the corner or in a place that is easily corroded Get better. This eliminates the necessity of installing more than the required number of dissimilar metals that are lower than copper used as a sacrificial anode, prolongs the life of wire mesh made of copper or copper alloy, and reduces the total cost of living cages Becomes

According to the third aspect, it is possible to adjust the degree of corrosion of the underwater structure made of copper or copper alloy in the vicinity of the draft portion by a very simple method. Further, the potential of the draft portion of the underwater structure is adjusted from the natural potential of the copper or copper alloy wire in the sea by the adjusting means to a potential of 50 to 200 m.
By making the adjustment low within the range of V, it is possible to adjust the degree of corrosion of the copper or copper alloy underwater structure regardless of the place, season, or the like. By this, for example, in the summer, when algae and shellfish are likely to adhere, the potential is adjusted higher,
Slightly corrodes copper or copper alloy to prevent algae and shellfish from sticking. In addition, in the season when the algae and shellfish are hard to adhere and the wave is rough, the potential is adjusted lower to prevent corrosion of copper or copper alloy. It is possible to always maintain a state in which algae, shellfish, and the like are not easily attached to the fish by a simple method.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a fish cage for fish culture according to the present invention.

FIG. 2 is a schematic view of a corner portion of a fish cage for fish culture according to the present invention as viewed from the front.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Living cage 2 Inner frame 3 Outer frame 4 Float 5 Metal lower than copper used as sacrificial anode 6 Adjusting means 7 Connecting means 10 Wire mesh made of copper or copper alloy wire

Claims (3)

[Claims] An underwater structure made of copper or a copper alloy and provided with a draft portion, a dissimilar metal provided near the draft portion and lower than the copper or copper alloy, Copper or copper alloy underwater provided with anticorrosion, comprising: connection means for electrically connecting the structure; and adjustment means provided on the connection means for adjusting a potential difference between the dissimilar metal and the structure. Structure. 2. The fish cage for aquaculture, wherein the underwater structure is formed of a wire mesh of copper or copper alloy wire, wherein the dissimilar metal is provided near a corner of the square shape. The copper or copper alloy underwater structure provided with corrosion protection according to claim 1. 3. An underwater structure made of copper or copper alloy and having a draft portion is immersed in the vicinity of the draft portion with a dissimilar metal lower than copper or a copper alloy. A copper or copper alloy, wherein the potential of the draft portion of the undersea structure is adjusted to be 50 to 200 mV lower than the natural potential of the copper or copper alloy by electrically connecting the copper or copper alloy to the underwater structure. Corrosion protection for underwater structures.