JPS5941430A - Antifouling metallic material - Google Patents

Abstract

PURPOSE:To obtain the antifouling metallic material having an excellent antifouling property and natural electrode potential nearly equal to or lower than those of carbon steel, cast steel and cast iron, by forming said material out of the specified amounts of In and Sn. CONSTITUTION:The composition of the antifouling metallic material is made as follows; by wt% 0.005-50 In, and the balance Sn and inevitable impurities; 0.005-50 In, Zn<30, and the balance Sn and inevitable impurities; or 0.005-50 In, Zn<30, Cu<10, and the balance Sn and inevitable impurities. Since this antifouling metallic material has natural electrode potential equal to or lower than those of carbon steel, cast steel and cast iron, the galvanic corrosion of a structural body is eliminated by attaching the antifouling metallic material to it. Hence, it is not necessary to apply electric insulation between the structural body and the antifouling metallic material. In addition, said metallic material has an excellent antifouling property, too.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a metal material that has antifouling properties (this effect is called antifouling).

Traditionally, when marine organisms attach to ships or marine structures, the speed of the ship decreases and fuel efficiency deteriorates. Accelerates corrosion of ships and offshore structures, shortening their lifespan. In addition, the attached organisms detached and became entangled in seawater lines and condensers.

Block these. There were various problems such as poor appearance. Therefore, we applied antifouling paints containing suboxide steel and organic tin compound antifouling agents.

Materials with antifouling effects such as copper and Cu-Mn alloys, % cupronickel, and copper alloys have been used.

However, these antifouling paints and antifouling metal materials also have the following drawbacks.

In the case of anti-fouling paints (1) Ships with anti-fouling paint applied to the outside of the hull have a short anti-fouling lifespan, as they must be docked periodically to remove attached organisms and reapply the paint.

(2) There is a limit to the amount of antifouling agent that can be contained in antifouling paints.

(3) Antifouling paints have low strength and adhesive strength, and the coated surface is easily damaged and easily peeled off.

For copper and copper alloys (1) When applied to submerged parts of ships and offshore structures.

Since the natural electrode potential of copper and copper alloys in seawater is more noble than that of carbon steel, they must be electrically insulated from ships and marine structures to prevent electrolytic corrosion.

In the case of tin (Sn) The stain resistance is not sufficient.

The present invention solves the drawbacks of the above-mentioned prior art, and uses carbon steel that has excellent antifouling performance and a natural electrode potential in seawater.

Obtain antifouling metal materials that are almost equivalent to or worse than cast steel and cast iron, and can be used for corrosion-resistant materials with structural members.
The purpose of the present invention is to provide an antifouling metal material that can be easily thermally sprayed or clad with steel without the need for electrical insulating materials.

Therefore, the antifouling metal material of the present invention has the following properties (1) to (3):
The gist is:

(1) An antifouling metal material containing 0,005 to 50% indium and the balance consisting of tin and normally included impurities. (2) Containing 0,005 to 50% indium and 30% or less of zinc, with the balance consisting of tin and normally included impurities. (3) An antifouling metal material that contains 0005 to 50% indium, 30% zinc, and 10% or less copper, with the balance being tin and other impurities that are normally included.In general, the problem of electrolytic corrosion is 2. It can be understood by considering the difference in the natural electrode potential of different materials. If the antifouling metal material is more sensitive than the structural material, if the structural material becomes electrically conductive with seawater for some reason, an electric circuit consisting of the antifouling metal material, structural material, and seawater will be created, and a large amount of the structural material will dissolve.

In particular, when most of the structure is covered with an antifouling metal material and only a portion of the structural material is exposed, the current density of the structural material serving as an anode becomes large, and only that portion is locally dissolved.

Therefore, conventionally, to avoid this, electrical insulation is provided between the structural material and the antifouling metal material. On the other hand, when the antifouling metal material is more base than the structural material, even if the structural material comes into contact with seawater, the antifouling metal material dissolves and prevents electrolytic corrosion of the structural material. That is, the antifouling metal material acts as a sacrificial anode.

Note that if the area of the structural material that comes into contact with seawater is much smaller than the antifouling metal material, the current density flowing per unit area of the antifouling metal material will be small.

This has the effect that the amount of dissolution per unit area is also small. Further, the larger the potential difference, the larger the current resistance, so in order to save the amount of dissolved antifouling metal material, it is preferable to bring the natural electrode potential of the antifouling metal material as close as possible to that of the structural material.

Next, limit the component range of each element.1. Indicate the reason why.

Indium (In) Indium is an effective element for keeping the natural electrode potential in the seawater of the present invention base and stably exhibiting antifouling performance, but if the amount added is less than 5% o or oo, the desired The above properties cannot be imparted to the alloy. Also, the amount added is 50
If the amount exceeds 0.0005%, self-corrosion will suddenly increase and antifouling properties will decrease, so the amount added is limited to 0.005% to 50%.

Zinc (Zn) Zinc is an element effective in lowering the natural electrode potential in seawater and improving corrosion resistance.

If the amount added exceeds 30%, the antifouling properties will deteriorate.

Alternatively, the amount of self-corrosion increases and the corrosion resistance deteriorates, so the amount added should be 30% or less (7).

Copper (Cu) Copper is an effective element for improving antifouling properties and corrosion resistance, but if the amount added exceeds 10%, the natural electrode potential in seawater cannot be kept lower than that of carbon steel. Addition amount is 10%
Toshida below.

Tin (Sn) Tin is an effective element for preventing or suppressing the adhesion of marine organisms, and the natural electrode potential in seawater is closer to that of steel than copper and copper alloys.9 The alloy of the present invention is based on tin. did.

The present invention will be explained to His Highness using examples.

Table 1 shows the antifouling performance and natural electrode potential in seawater of the antifouling metal material of the present invention and comparative materials.

The comparative materials tin, copper, and 9/1 Kipronickel were commercially available materials, and the Cu-Mn alloy was 50 kg.
The material was melted in a high-frequency melting furnace, cast into a mold, and then hot forged. All other materials used were those melted in an electric furnace in which an inert gas was passed for 5002 hours.

The antifouling performance was evaluated by immersing a plate-shaped specimen with a length of 9 oWn, a width of 7 oW, and a thickness of 3 WrIn in seawater (depth of 1 m) for about 3 months in summer on a raft in a certain port.

1. The measurement of natural electrode potential in seawater is 1011111.
Testing was carried out in air-saturated seawater using a saturated potassium chloride silver chloride electrode as a reference electrode using a dice-shaped test piece measuring 1×10 mm×] and 0 mm.

Incidentally, the natural electrode potential of carbon steel was -630 mV, but the natural electrode potential of cast iron and cast steel is roughly the same.

Table 1 If conventional antifouling metal materials are directly bonded to a grid structure, electrolytic corrosion will occur, which is a problem. There is no longer any need for electrical insulation between the two. As a result, the work of installing the antifouling metal material becomes easier.

Cladding and thermal spraying of antifouling metal materials are also possible.

In addition, the antifouling metal material of the present invention exhibits superior antifouling performance than conventional cupronickel and tin, so it can be used for ships, offshore plants, marine structures, and seawater desalination equipment, such as ■ Ship hull outer panel material S , Ia scent oil drilling equipment, ■ Offshore storage tanks, ■ Piers, buoys, buoys, lighthouses, ■ Seawater intake pipes and screens, ■ Addition to antifouling paints, ■ Seawater bongs, motors, ■ Seawater valves, ■ Heat exchanger using seawater, [Phase] Chain/rope for seawater, equipment for aquaculture of seawater species, @
Applicable to inboard and outboard motors, ◎ fishing gear equipment, and general parts abduction in the 0 dock.

Claims (2)

[Claims] (1) An antifouling metal material characterized by containing o, oos to 50% (weight percent, hereinafter referred to as indium) of indium, with the remainder consisting of tin and impurities that are normally included. (2) Indium: o, oos~5o%, zinc: 30%
(3) An antifouling metal material characterized by containing the following, the remainder being tin and impurities normally included (3) indium, o,
An antifouling metal material characterized by containing 30% or less of zinc, 10% or less of copper, and the balance consisting of tin and normally contained impurities.