JP2001030986A - Corrosion protective method in high-speed boat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a corrosion-protective method for a high-speed boat capable of surely protecting the corrosion. SOLUTION: In the corrosion-protective method of a high-speed boat having a stainless steel hydrofoil 3 mounted on a bottom part of an aluminum hull 2, a specified surface of the hull 2 is painted, Zn and Al are thermally sprayed to a surface of the hydrofoil 3 to form a film thereon, an insulation sheet 24 is inserted in a fitting part of the hydrofoil 3 to the hull 2, connection pieces are insulated, and a lower sacrifice anode and an upper sacrifice anode are mounted on a keel part of the hull 2 and above a side of the hull 2, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anticorrosion method for a high-speed ship.

[0002]

2. Description of the Related Art Generally, aluminum is used as a constituent material of a hull of a high-speed ship such as a hydrofoil ship, and high strength steel, stainless steel, etc. Is used. Conventionally, when performing corrosion protection on such an aluminum hull, a sacrificial anode is provided to perform electrolytic protection.

[0003]

However, even when a sacrifice anode is provided on the hull, electric corrosion (galvanic corrosion) occurs because the materials of the hull side and the hydrofoil side are different from each other, and corrosion occurs on the aluminum hull. There is a problem that it cannot be avoided. Then, an object of the present invention is to provide a corrosion prevention method in a high-speed ship which can perform corrosion protection more reliably.

[0004]

In order to solve the above-mentioned problems, a corrosion prevention method for a high-speed ship according to the present invention comprises an aluminum hull having a bottom portion made of a dissimilar metal material such as high-tensile steel or stainless steel. A method for anticorrosion of a high-speed ship to which a hydrofoil is attached, wherein a coating is applied to a predetermined surface of a hull, and a film is formed by spraying Zn metal and Al metal on the surface of the hydrofoil. In the method, while inserting an insulating material into the mounting portion of the hydrofoil to the hull, it is a method of performing insulation treatment also to each other coupling tool,
Further, in these anticorrosion methods, a sacrificial anode or a power supply anode connected to an external power supply is attached to the hull side.

According to each of the above-described anticorrosion methods, in a high-speed ship in which an aluminum hull is provided with a hydrofoil made of dissimilar metal of a different material, the surface of the hull is painted and the surface of the In addition, since a coating is formed by thermal spraying of Zn metal and Al metal, electric corrosion between the hull and the hydrofoil can be prevented. By performing the insulation treatment also on the connecting member provided in the portion, it is possible to prevent electric corrosion which is likely to occur in the mounting portion having a complicated structure. Further, by attaching a sacrificial anode or a power supply anode to the hull side, even when painting or insulation treatment is insufficient, electric corrosion can be more reliably prevented.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a high-speed ship according to an embodiment of the present invention; FIG. In this embodiment, a case of a hydrofoil ship as a high-speed ship will be described. That is, as shown in FIG. 1, the hydrofoil 1 has a catamaran hull (hereinafter referred to as a hull).
The two hulls 2a are provided with a hydrofoil 3 at the front and rear positions at the front and rear positions. The catamaran hull 2 is made of aluminum, and the hydrofoil 3 is made of stainless steel. ing.

[0007] A predetermined surface of the hull 2 (at least a part immersed in seawater) is coated with a predetermined paint. That is, the surface of the hull 2 is coated with an epoxy anti-corrosion paint for anti-corrosion ships and an anti-fouling paint for preventing biofouling. In coating, a primer and a putty are used in order to obtain adhesion and smoothness of the coated surface.

On the surface of the hydrofoil 3, Zn metal and A
The metal is sprayed to form an alloy film. That is, as shown in FIG. 2, after performing sandblasting as a base treatment of the stainless steel 11, the ratio of the zinc material (for example, Zn wire) to the aluminum material (for example, Al wire) is 45:55 (%). Each of the molten metals was simultaneously sprayed by a thermal spraying machine set so that the thermal spray coating 12 was formed on the surface thereof.

Then, in order to perform a sealing treatment on the surface of the thermal spray coating 12, an epoxy primer 13 dedicated to Al diluted about 30 times with a thinner is applied.
Finally, an epoxy resin 14 was applied. in this way,
The spontaneous potential of the sprayed coating of the alloy of Zn metal and Al metal formed on the surface of the stainless steel hydrofoil 3 is −1030.
−1080 mV, and the natural potential of aluminum is −
850mV, the natural potential of stainless steel is -0.09mV
(See FIG. 5; FIG. 5 is a graph showing the relationship between the salt spray time and the natural potential of each metal).

[0010] Further, by applying metal spraying to the surface of the hydrofoil 3, the impact strength is stronger and the maintenance period of the high-speed ship becomes longer, as compared with ordinary coating,
It is economical. Further, an insulation treatment is also applied to a mounting portion between the hull 2 and the hydrofoil 3. That is, as shown in FIG. 3, a plate-shaped mounting flange portion 21 provided at the bottom of each body portion 2 a of the hull 2, and brackets 2 at both ends of the hydrofoil 3.
An insulating sheet (insulating material) 24 is inserted between the mounting flange portion 23 and the plate-like mounting flange portion 23 provided therebetween, and a connecting tool for connecting the mounting flange portions 21 and 23 to each other, that is, a connecting member. High strength stainless steel bolt 25
Is covered with a sheath tube (also referred to as a sheath) 26 made of an electrically insulating resin, and a washer 27 formed of an electrically insulating material is also used.

As described above, the insulating sheet 24 is also inserted into the portion where the hull 2 and the hydrofoil 3 are attached, and the bolts 25, washers 27, etc., which are the connectors, are also made of an insulating material. , Electric corrosion at a contact portion between dissimilar metals is reliably prevented. Further, a sacrificial anode 31 is attached to the hull 2 side in order to more reliably perform the above-described anticorrosion by painting.

More specifically, as shown in FIG.
Hull part which receives little resistance from water, eg keel part 2
b, on both sides and on the downstream side of the hydrofoil 3, a sea-shell type (for example, a width of about 100 mm and a length of about 1000 mm, and a semi-conical drainage portion is joined to both ends to reduce cavitation erosion. Lower sacrificial anodes 31A of different shapes (for example, three) are mounted on the sea surface at the time of cruising, but are positioned below the sea surface at the time of berthing and exhibit their functions.
A plurality (for example, four) B are attached to both side surfaces of each body 2a at predetermined intervals.

As described above, the aluminum hull 2
In a high-speed ship equipped with a hydrofoil 3 made of a dissimilar metal of a different material, the hull 2 is subjected to anticorrosion coating and a sprayed coating 12 of an alloy of Zn metal and Al metal is formed on the surface of the hydrofoil 3. Therefore, it is possible to reliably prevent electric corrosion between the hull 2 and the hydrofoil 3, and to insulate the connecting member provided at a portion where the hydrofoil 3 is attached to the hull 2 by using an insulating material. Since the treatment is performed, it is possible to prevent electric corrosion that is likely to occur in the mounting portion having a complicated structure.

Further, the lower and upper sacrificial anodes 31A and 31B are mounted at the keel portion 2b of the hull 2 and at a position where it is immersed in seawater only at the time of anchoring, that is, at upper and lower positions.
At the time of berthing, both the sacrificial anodes 31A and 31B can provide a sufficient anticorrosion current and the anticorrosion potential on the hull.
The distribution of the anticorrosion current becomes uniform, and the anticorrosion effect is more reliably exhibited.
Since only 1A is located below the sea level, the propulsion resistance of the hull is also reduced.

In the above embodiment, the sacrifice anode is attached to the hull. However, for example, a power supply anode connected to an external power supply provided on the hull and supplied with electric current from the outside can be attached. Further, in the above-described embodiment, the case where the hydrofoil is made of stainless steel has been described. However, the present invention can be applied to a case where the hydrofoil is made of high-tensile steel.

Further, the hull shape of the hydrofoil in the above embodiment has been described as applied to the case of a catamaran hull. However, it is needless to say that the invention is applicable to a case where a hydrofoil is provided on a monohull. it can.

[0017]

As described above, according to the structure of the present invention, the surface of the hull is coated and painted on the aluminum hull on the high-speed ship in which the hydrofoil made of dissimilar metal different from the material is attached. Since the thermal spray coating of an alloy of Zn metal and Al metal is formed on the surface of the hydrofoil, electrical corrosion occurring between the hull and the hydrofoil can be reliably prevented. By performing insulation treatment on the portion to be attached to the hull and the connecting tool provided on this attachment portion, it is possible to prevent electric corrosion which is likely to occur on the attachment portion having a complicated structure. Further, by attaching a sacrificial anode or a power supply anode to the hull side, even when painting or insulation treatment is insufficient, electric corrosion can be more reliably prevented.

[Brief description of the drawings]

FIG. 1 is a bottom perspective view of a high-speed ship according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a hydrofoil of the high-speed ship.

FIG. 3 is a front sectional view showing a mounting portion of a hydrofoil in the high-speed ship.

FIG. 4 is a schematic front view showing a mounting position of a sacrificial anode in the high-speed ship.

FIG. 5 is a graph showing a relationship between a salt spray time and a natural potential in each alloy material.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 hydrofoil ship 2 catamaran hull 2 a trunk 2 b keel portion 3 hydrofoil 11 stainless steel 12 thermal spray coating 21 mounting flange portion 23 mounting flange portion 24 insulating sheet 25 bolt 26 sheath tube 27 washer 31 A lower sacrificial anode 31 B upper sacrificial anode

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Ryuichi Hotta 1-7-89 Minami Kohoku, Suminoe-ku, Osaka-shi, Osaka Inside Hitachi Zosen Corporation (72) Inventor Haruhisa Fukui 1-chome, Minami-Kohita, Suminoe-ku, Osaka-shi, Osaka No. 7-89 F-term in Hitachi Zosen Corporation (reference) 4K060 AA02 AA03 AA07 BA13 BA33 EA02 EB05 FA09

Claims (3)

[Claims] An anticorrosion method for a high-speed ship in which a hydrofoil made of a dissimilar metal material such as high-strength steel or stainless steel is attached to the bottom of an aluminum hull, wherein a predetermined surface of the hull is painted. A method for anticorrosion in a high-speed ship, comprising spraying Zn metal and Al metal on the surface of a hydrofoil to form a film. 2. The anticorrosion method for a high-speed ship according to claim 1, wherein an insulating material is inserted into a portion where the hydrofoil is attached to the hull, and an insulating process is performed on the connecting members. 3. The anticorrosion method according to claim 1, wherein a sacrificial anode or a power supply anode connected to an external power supply is attached to the hull.