JPH0764694B2 - Method of manufacturing biofouling prevention tube - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a biofouling prevention tube having a function of preventing the adhesion of marine organisms such as barnacles, purple shellfish and algae.

[0002]

2. Description of the Related Art Marine structures that are in contact with seawater are exposed to fouling such as marine life in seawater.
The appearance may be impaired or the original functions of the structure may not be exhibited. For example, in the case of a ship, the resistance increases due to the adhesion of sea life to the bottom surface of the hull and the like, and the propulsion speed of the hull decreases. Further, in the case of a thermal power plant, if marine organisms adhere to the seawater intake pit, the flow of seawater, which is a cooling medium, may be impaired, and power generation may have to be stopped.

Therefore, techniques for preventing the adhesion of marine organisms have been researched, and one of the techniques for preventing the adhesion of marine organisms that has been put into practical use is one of the paints containing cuprous oxide or organotin. Is applied to the contact surface of the marine structure with the seawater. In addition, JP-A-60-209505
The publication discloses a pressure-sensitive adhesive body for preventing bio-adhesion in which a primer layer is provided on one surface of a plate made of copper or copper alloy, and a pressure-sensitive adhesive layer is formed thereon.

[0004]

However, according to such a conventional antifouling method using a paint, even if the paint is applied thickly, the paint is easily peeled off, so that the life expectancy of a remarkable antifouling effect is It takes about one year at the longest, and complicated maintenance work such as reapplication is required every year. The marine organism adhesion preventive body disclosed in JP-A-60-209505 is copper or a copper-nickel (Cu-Ni) alloy, and its material is inferior in terms of corrosion resistance and antifouling performance.

According to many years of experimental research conducted by the present inventor, it has been found that when a specific beryllium copper alloy among various metals or alloys is used for an offshore structure, an extremely excellent antifouling effect can be obtained. It is presumed that this is because beryllium ions act synergistically with copper ions to exert a large repellent effect on marine organisms, and prevent adhesion and reproduction of marine organisms. It was found by the present inventor that the beryllium copper alloy has an effect of exhibiting an antifouling function and a continuous action of elution of copper ions.

An object of the present invention is to provide a simple method for producing a biofouling prevention tube which is excellent in durability, requires no maintenance, is nontoxic, and effectively prevents the adhesion and reproduction of marine organisms. Is.

[0007]

A method of manufacturing a biofouling prevention tube according to the present invention for solving the above-mentioned problems comprises a strip of beryllium copper alloy spirally wound, and adjacent side strips of adjacent strips are spirally wound. It is characterized in that the convex portion and the concave portion are fitted so as not to move in the axial direction, and thereafter, an electrically insulating resin is formed on the outer periphery of the strip-shaped thin plate.

The beryllium-copper alloy contains copper as a main component and has a beryllium content of 0.2 to 2.8% by weight, and is a Be-Cu alloy, a Be-Co-Cu alloy, a Be-C.
It is characterized in that it is any one selected from the group consisting of o-Si-Cu alloys and Be-Ni-Cu alloys.
The composition of the beryllium copper alloy is, for example, Be: 0.
2 to 1.0 wt%, Co: 2.4 to 2.7 wt%, balance Cu and unavoidable impurities, Be: 0.2 to 1.0 wt%, Ni: 1.4 to 2.2 wt%, The balance Cu and unavoidable impurities, Be: 1.0 to 2.0% by weight, Co: 0.
2 to 0.6% by weight, balance Cu and inevitable impurities, B
e: 1.6 to 2.8% by weight, Co: 0.4 to 1.0% by weight, Si: 0.2 to 0.35% by weight, balance Cu and inevitable impurities.

The content ratios of cobalt, nickel and silicon selectively contained in the beryllium copper are preferably in the following ranges, respectively. Cobalt (Co): 0.2 to 2.7% by weight Nickel (Ni): 1.4 to 2.2% by weight Silicon (Si): 0.2 to 0.35% by weight Purpose of addition of each element, addition The reasons for limiting the upper limit and the lower limit of the range are as follows.

Beryllium (Be): 0.2 to 2.8% by weight Be is added so that when a biofouling-preventing body is immersed in seawater, Be is eluted to exhibit a biofouling-preventing effect, and beryllium is added. This is to improve the properties such as strength and corrosion resistance of the copper alloy, to improve the manufacturability such as heat treatment and grain size adjustment, and to improve the formability and castability. If Be is less than 0.2% by weight, the above effects (1) to (7) are not sufficiently exhibited. When Be exceeds 2.8% by weight, the wrought workability deteriorates and the cost becomes economically expensive.

Cobalt (Co): 0.2 to 2.7 wt% Co is added to form fine CoBe compounds and disperse them in the alloy to obtain mechanical properties, heat treatment properties, grain size adjustment, etc. This is for improving the manufacturability of. Co is 0.2
If it is less than wt%, the above-mentioned effects cannot be sufficiently exhibited.
This is because when Co exceeds 2.7% by weight, the flowability of the molten metal deteriorates, the above properties are hardly improved, and the cost becomes economically expensive.

Nickel (Ni): 1.4 to 2.2 wt% Ni is added to form fine NiBe compounds and disperse them in the alloy to obtain mechanical properties, heat treatment properties, grain size adjustment, etc. This is for improving the manufacturability of. Ni is 1.4
If it is less than wt%, the above-mentioned effects cannot be sufficiently exhibited.
This is because when Ni exceeds 2.2% by weight, the flowability of the molten metal deteriorates, the above properties are hardly improved, and the cost becomes economically expensive.

Silicon (Si): 0.2 to 0.35 wt% Si is added to improve the flowability of the beryllium alloy. If Si is less than 0.2% by weight, the effect is not sufficiently exhibited, and if Si is more than 0.35% by weight, the alloy becomes brittle and the toughness deteriorates.

[0014]

According to the method for producing a biofouling prevention tube according to the present invention, a strip-shaped thin plate of beryllium copper alloy is spirally wound, and the side portions of adjacent strip-shaped thin plates are fitted with a convex portion and a concave portion so as not to move in the spiral axial direction. After that, since the electrically insulating resin is formed on the outer periphery of the strip-shaped thin plate, the beryllium-copper alloy thin plate can be lined on the peripheral wall of the tube, which is difficult to process, by a simple means.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. 1st Example of this invention regarding the manufacturing method of the pipe body which flows seawater is shown in FIG.1 and FIG.2. As shown in FIGS. 1 and 2, the strip-shaped thin plates 2 of beryllium copper alloy are spirally wound, and the convex portions 6a and the concave portions 6b of the adjacent strip-shaped thin plates 2 are fitted together. This prevents the strip-shaped thin plate 2 from moving in the axial direction. Thereafter, an electrically insulating resin (not shown) is formed on the outer circumference of the strip-shaped thin plate 2 to form a tubular body.

The obtained tubular body has a strip-shaped thin plate 2 of beryllium copper alloy formed on the inner wall surface. As a result of many years of experimental research conducted by the present inventor, as described above, it was found that the beryllium copper alloy has the effect of exhibiting the antifouling function (antibiotic function) and the continuous action of elution of copper ions. The effect of exhibiting the antifouling function and the sustained action of elution of copper ions are described in detail below.

Effect of Antifouling Function The ionization tendency of beryllium, copper and nickel is Be> N
It is known from the literature that i> Cu, indicating that the element on the left is more likely to elute. In the case of beryllium copper, beryllium elutes first to form a local battery to exert a biofouling prevention effect due to the current effect, and the beryllium ion takes an oxidized form called internal oxidation. This internal oxidation forms a BeO film inside, for example, as shown in FIG. 3, but since this BeO film is porous, elution of copper is allowed to form Cu ₂ O + BeO on the surface. It is considered that the antifouling function is exhibited by the elution of this copper ion into seawater.

Sustaining action of copper ion elution The above-mentioned effect of exhibiting the antifouling function has a continuing action of eluting copper ions. That is, beryllium copper has an action of continuing the antifouling function without stopping. A dense surface oxide (Cu ₂ O) is formed on the surface of beryllium copper that comes into contact with seawater. However, as shown in FIG. 3, in the lower layer of the surface oxide, internal oxidation of porous BeO is performed. A film of matter is formed. Therefore, the elution of copper into seawater is maintained, and the volume of this film increases due to oxidation. When the volume increase of the film reaches a certain amount, the oxide film on the surface is separated from the porous internal oxide layer. Therefore, it is considered that the electrochemical action and the elution of copper are maintained for a long time.

Further, the continuous action of copper ion elution generated by beryllium copper will be explained as follows using the schematic diagram shown in FIG. 5 when comparing beryllium copper and cupro-nickel. As shown in FIG. 5, when beryllium copper (BeCu) has a certain thickness of a corrosion product (oxide), the corrosion product is peeled off. Then, the surface of the beryllium copper alloy appears, and the thickness of the corrosion product increases as the corrosion progresses again. Then, the corrosion product is peeled off again when it reaches a certain thickness, which is repeated. On the other hand, the elution of ions decreases as the thickness of the corrosion product increases, which gradually decreases. However, when the corrosion products are peeled off as described above, the surface of the alloy appears and the amount of ion elution increases. Therefore, the increase and decrease of copper ion elution are repeated.

The beryllium copper of the embodiment of the present invention has a copper ion elution sustaining action due to the peeling of the oxide film. As a result, the amount of marine organisms adhering to the surface of copper beryllium is small or hardly adhered. On the other hand, as shown in FIG. 4, in the case of cupro-nickel (CuNi) of the comparative example, dense nickel oxide NiO ₂ or copper oxide Cu ₂ O is formed in the surface layer over a certain period of time. This is because the elution of copper ions is suppressed as shown in FIG. This is due to ionization tendency (Be>
According to Ni> Cu), in the case of cupro nickel, nickel (Ni) is considered to preferentially elute to form a local battery, which is due to the formation of a dense oxide on the surface as shown in FIG. Therefore, as shown in FIG. 5, in the case of cupro-nickel, the thickness of the corrosion product initially increases with time, but the growth rate of the corrosion product gradually decreases. At the same time, the elution amount of copper ions gradually decreases. Moreover, with Cupro nickel, flaking of corrosion products does not occur as easily as with copper beryllium. Therefore, the elution amount of ions remains at a low level, and the antifouling effect decreases.

The inventors of the present invention have for the first time discovered that the beryllium copper alloy has such remarkable antifouling effect and copper ion elution sustaining effect. The present inventor is unaware of any prior art document that refers to or points out. As a practical beryllium copper alloy, 11 alloys having a beryllium content of 0.2 to 0.6% by weight and a beryllium content of 1.8 to 2.0% by weight.
Various alloys such as No. 25 alloy are specified by JIS, but those having a beryllium content of 1.6% or more are preferable in terms of antifouling effect. When the content of beryllium exceeds 2.8%, beryllium does not form a solid solution in copper any more, so that the antifouling effect is excellent but the wrought workability is gradually reduced.

[0022]

As described above, according to the method for producing an organism adhesion preventing pipe of the present invention, a marine organism adhesion preventing pipe can be produced by a relatively simple operation. Further, according to the antifouling structure attached by this method, there are effects that it is excellent in corrosion resistance, maintenance work is simple, there is no problem of toxicity, and the adhesion of marine life is effectively prevented.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a method of manufacturing a biofouling prevention tube according to a first embodiment of the present invention.

FIG. 2 is a cutaway enlarged sectional view of a portion A shown in FIG.

FIG. 3 is a schematic diagram showing a state of an oxide film of beryllium copper according to an example of the present invention.

FIG. 4 is a schematic view showing a state of an oxide film of cupro nickel of a comparative example.

FIG. 5 is a schematic explanatory view comparing changes over time in the amount of copper ions eluted and the thickness of corrosion products for beryllium copper and cupro nickel.

[Explanation of symbols]

 2 band-shaped thin plate 6a convex portion 6b concave portion

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C22C 9/00

Claims (2)

[Claims] 1. A strip-shaped thin plate of beryllium copper alloy is spirally wound, and adjacent side portions of the strip-shaped thin plate are fitted with a convex portion and a concave portion so as not to move in the spiral axis direction, and thereafter, the outer periphery of the strip-shaped thin plate. A method for producing a biofouling prevention tube, characterized in that an electrically insulating resin is formed on the tube. 2. The beryllium copper alloy contains copper alloy as a main component and has a beryllium content of 0.2 to 2.8% by weight, and is a Be—Cu alloy, a Be—Co—Cu alloy, a Be—C.
The method for producing a biofouling prevention tube according to claim 1, wherein the biofouling prevention tube is selected from the group consisting of an o-Si-Cu alloy and a Be-Ni-Cu alloy.