JPS6082637A - Stain-proof metallic material - Google Patents

Abstract

PURPOSE:To prevent or retard deposition of aquatic living matter to parts submerged in water or draft line structures by prepg. a stain-proof metallic material from specified range of content of tin, residual content of Zn and usually contained impurities. CONSTITUTION:A stain-proof metallic material comprising 20-60wt% Sn, or additionally, <=20wt% Cu, together with residual wt% Zn and usually contained impurities. The material has superior stain-proofing effect and equal or less natural electrode potential as or than carbon steel, cast steel, and cast iron. No electric insulating material is necessary for preventing galvanic corrosion generated by the contact with a structure member and is suited for thermal spraying or cladding with Cu. Since the material is more effective in the stain-proofing property than conventional cupronickel and tin it is suitable for the material for ships, marine surface plant, marine construction, or for a plant for converting sea water to fresh water.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to the introduction of water to aquatic organisms.
It is related to 42 metal families that prevent or suppress fouling (this action is called antifouling).

Traditionally, ships and marine structures have been exposed to marine life.
If this occurs, the ship's speed will decrease and fuel efficiency will deteriorate, and the corrosion of ships and marine artifacts will be accelerated and their lifespan will be shortened. There have been various problems such as getting caught up in heat exchangers and the like, causing them to become clogged, and poor camouflage.

Therefore, we applied antifouling paints containing antifouling agents such as cuprous oxide and organic tin compounds, and coated with copper coatings and Cn-Mn alloys.
Copper alloys with antifouling properties, such as copper alloys containing yellow nickel, have been used.

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

In the case of anti-fouling paints (1) Even on ships coated with anti-fouling paints, it is not possible to completely prevent the build-up of living organisms. The antifouling lifespan is poor, such as having to be taken to the C dock regularly.

(2) There is a limit to the amount of antifouling agent that can be contained in antifouling paints, and the antifouling effect cannot be maintained for a long period of time.

(3) Antifouling paint (RI strength and adhesive strength are weak, the coated surface is easily damaged by floating objects on the sea surface, etc., and it is easy to peel off.

For copper and copper alloys (1) When applied to submerged parts of ships and marine artifacts.

Copper and copper alloys have a higher natural electrode potential in seawater than carbon steel, so they must be electrically insulated from ships and marine structures to prevent corrosion.

In the case of tin (Sn) (1) The natural electrode potential of tin in seawater is approximately 1,400m
v, and carbon steel is also to blame. The antifouling property between the length of 1υ is still insufficient.

The present invention solves the drawbacks of the above-mentioned prior art and provides an antifouling metal material that has excellent anti-Fi performance and a natural battery potential in seawater that is approximately equal to or lower than that of carbon steel, cast steel, and cast iron.
The purpose of the present invention is to provide 13 types of antifouling metals that do not require electrical insulating materials to prevent galvanic corrosion/yon with structural members and are easy to remove by thermal spraying or cladding with copper.

Therefore, the antifouling metal material of the present invention has the following (1) and (2)
) is its gist.

(1) An antifouling metal material characterized by containing 20 to 60% tin, with the remainder consisting of zinc and impurities that are normally included.

(2) Contains 20 to 60% tin and 20% or less copper.

It is an antifouling metal material characterized by the balance being zinc and usually contained.

Generally, the problem of electric current is understood by considering the difference in natural electrode potential between two types of gains. If the antifouling metal material is more sensitive than structural material A and is not electrically insulated, if the structural material becomes conductive to seawater for some reason, the antifouling metal material - Structural Materials Engineer - 1 -
'ru consisting of seawater.

Air circuits occur and structural materials begin to dissolve. 'r! j K
When most of the structure is covered with the antifouling metal material and only a portion of the structural material is exposed, the current density of the structural material serving as an anode increases, so that only that portion is locally dissolved.

Therefore, in order to avoid this problem, structural materials and antifouling metal phase f have conventionally been used.
This provides electrical insulation between the two. 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 an iSI pole. Furthermore, if the area of the +14 antifouling 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, so the dissolution tube per unit area will also be small. This has the effect of In addition, the larger the potential difference, the larger the amount of current, so in order to save the amount of molten water in the antifouling metal material, it is necessary to
It is preferable to bring the potential as close as possible to that of the structural material.

Next, the reason for limiting the component range of each element will be explained.

Tin (Sn) Tin is an element effective in preventing or suppressing the adhesion of marine organisms, but if the amount added is less than 20 LII, the antifouling effect will not be sufficient.

If it exceeds 60%, the natural potential of the alloy in seawater cannot be kept lower than that of carbon steel over a long period of time, so the amount added is set to 20 to 60%.

Copper (Cu) Copper is an effective element for improving antifouling properties and corrosion resistance, and especially when coexisting with Sn, antifouling properties increase, but if the amount added exceeds 20%, the natural potential of the alloy in seawater will decrease. Since it is not possible to maintain carbon steel's annealing over a long period of time, the amount added is set to 20% or less.

Zinc (Zn)! 11 Since lead is an element effective in maintaining the potential in seawater over a long period of time, it was used as the heath of this alloy.

The present invention will be explained below using Examples.

Table 1 shows a comparison with the antifouling metal material of the present invention (auxiliary antifouling performance and natural electrode potential in seawater).

In addition, commercially available materials are used for tin, copper, etc. and 9/1 carbon steel, and Cu-Mn alloys are melted in a high-frequency melting furnace, cast into a mold, and then hot forged. was used. For all other eye materials, 500 g of No. 42 was melted in an electric furnace through which an inert gas was flowed.

Antifouling performance - Length 60 mm, width 40 yn, thickness 3 mm board 1
The test pieces were immersed in water (depth im) for about 8 months during the summer on a raft in a certain port, and the results were evaluated.

Unfortunately, the measurement of natural anal potential in seawater is 10m+n'.
Using a rod-shaped test piece measuring 50 x 50 mm, a saturated potassium chloride silver chloride electrode was used as a reference electrode in seawater.

In addition, the natural electrode potential φ of carbon steel is -650 to -700 mV
However, the natural electric potential of cast iron and cast steel is about the same as that of Daisetsu.

Double bottom left ω゛′”: bei゛i,.

1. As stated above, the antifouling metal material of the present invention uses a saturated potassium chloride silver chloride electrode as the group 1lII'tIt electrode.

Carbon steel, cast iron and cast steel have the same natural electrode potential +M I
ff or less, so electrolytic corrosion, which is a problem when conventional antifouling metal materials are bonded directly to structures, is less likely to occur. There is no longer any need for electrical insulation between the two. As a result, it becomes easy to attach the antifouling metal (A material) to the structure, and it becomes possible to clad and thermally spray the antifouling 7Tj metal material.

Second, the antifouling metal material of the present invention exhibits superior antifouling performance than conventional cupronickel and tin, so it can be used in ships, offshore plants, oceans (i7+ structures, seawater desalination equipment, etc.). Rebellion gain, 2: oil rig, 3: offshore storage tank, 4: pier, buoy, buoy, lighthouse.

5: Still water intake pipe and scrubber IJ-y, 6: Addition to antifouling paint, 7: Seawater pump, motor.

8: Pulp for ms water, 9: Heat exchanger using seawater.

10: Chains and robes for seawater, 11: Various types of seawater aquaculture equipment, 12: Boats and boats, 13: Fishing equipment, 14: General abduction of parts used in dogs, etc.

Claims (1)

[Claims] An antifouling metal material characterized in that (1) contains 20 to 60% by weight of tin (hereinafter simply referred to as tin), with the remainder consisting of zinc and impurities normally contained. +21 "An antifouling metal material characterized by containing 20 to 60% of itability and 20% or less of copper. The balance consists of zinc and impurities normally included.