JPS581701B2 - Zinc coating defect repair agent and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a steel material coated with a zinc coating, in which when a defect occurs in the zinc coating due to gas cutting or welding, the coating is applied to the defect to repair the defect, and the defect can be effectively repaired. The present invention relates to an excellent zinc coating defect repairing agent that can be used to repair defects in zinc coating without adversely affecting the zinc coating surrounding the repaired area, and a method for producing the same.

Generally, steel products that are exposed to the atmosphere, wind and rain, and other corrosive atmospheres are plated with metal zinc, which has excellent corrosion resistance, for purposes such as corrosion prevention, appearance, and commercial value. Items that are difficult to fully plate due to their shape, dimensions, mechanism, etc., such as items that are difficult to immerse in a molten zinc bath, or items that require welding during assembly, are plated locally or individually. Corrosion and rust prevention measures are taken by painting.

In particular, ship sacrificial piping is galvanized on the ground and then installed inside the ship, but due to dimensional accuracy, some pipes are cut and shortened or other pipes are joined to extend them. are extremely common.

In this case, the zinc coating of the gas cut portion and welded joint portion of the galvanized steel pipe is burned out due to high temperature heating, resulting in the need for re-plating work.

Conventionally, these burnt and damaged zinc coatings have been repaired by applying paint containing metallic zinc or by tin-lead alloy solder, but these have caused problems such as peeling, discoloration, and corrosion due to lack of anti-corrosion performance. There are many points.

The present invention eliminates these drawbacks, forms a coating with high adhesive strength and good corrosion resistance uniformly on the steel surface in a short time, and
This was proposed for the purpose of preventing staining of the zinc coating in areas other than the defective areas, and contains 30 to 50% by weight of metallic zinc powder (
(% below indicates weight %), 10-20% of metal tin powder, 20-30% of ammonium chloride, 1 part of zinc chloride or tin chloride
5 to 25%, and a spreading agent such as liquid oil or fat to 5 to 25%.
Metal zinc powder 30 to 5
A mixture of 0% and 10 to 20% of metal tin powder and a mixture of 35 to 55% of ammonium chloride and zinc chloride or tin chloride are prepared in advance, and a mixture of these two types and a liquid oil or fat is spread. Provided is a method for producing a zinc coating defect repairing agent, characterized in that 5 to 10% of the agent is uniformly mixed and used in the form of a paste.

The repair agent of the present invention is made into a paste by adding a spreading agent such as liquid oil or fat, which is applied to the iron surface where the zinc coating is missing, and then heated with an oxygen/acetylene flame or propane gas flame to form a coating. .

In addition, since it is possible to mix metallic tin powder with metallic zinc powder and coat it at a temperature lower than the temperature during construction by immersion in a molten zinc bath, melt oxidation of other parts other than the repaired part where a coating has already been formed is prevented. can.

In addition, ammonium chloride, zinc chloride, or tin chloride is mixed with metal zinc powder or metal tin powder as a solvent, and a spreading agent such as liquid oil, water, or alcohol is added to prevent moisture absorption and form a paste that is easy to apply. did.

In this way, according to the present invention, a repair coating with good adhesion and anticorrosion properties can be easily formed in a short time, and the surrounding zinc coating is not contaminated during coating.

Next, a method for manufacturing the repair agent of the present invention will be explained.

Zinc chloride (ZnC 1 2) is a salt that easily dissolves in water, and its crystals quickly deliquesce in the air, and it also has the property of generating heat when dissolved in water.

When zinc chloride and metallic zinc powder are mixed in the same container, the zinc chloride absorbs moisture in the air and generates heat, and then the zinc chloride and metallic zinc powder undergo an exothermic reaction and harden while releasing hydrogen.

As a result, it becomes very difficult to mix the other components of the repair agent more uniformly.

Note that tin chloride also has the same properties as zinc chloride.

Therefore, when making a small amount of the repair agent of the present invention, it is necessary to quickly mix each component within the above composition range, so the manufacturing method first involves uniformly mixing metallic zinc powder, metallic tin powder, and ammonium chloride. , There are methods such as quickly mixing zinc chloride or tin chloride with this to mix it uniformly.

When producing in large quantities, such a method will cause solidification during mixing due to the above-mentioned reaction, making it impossible to produce a homogeneous mixture.

Therefore, it is necessary to prepare a mixture of ammonium chloride and zinc chloride or tin chloride in advance using the method of the present invention described above, and quickly and uniformly mix the other necessary ingredients therein.

For example, ammonium chloride and zinc chloride or tin chloride are uniformly mixed in one container, metallic zinc powder and metallic tin powder are uniformly mixed in another container, and then the mixture of these two types and a spreading agent such as liquid oil are added. Mix quickly and evenly.

By doing this, even when producing in large quantities, a uniform mixture can be obtained before it solidifies.

In this way, it is necessary to select the manufacturing method for the repair agent of the present invention depending on the amount of production, that is, the length of time required to mix uniformly. can do.

Note that some solvents containing ammonium chloride and zinc chloride are commercially available, and commercially available solvents may be used during production.

In this way, the repair agent of the present invention has a spreading agent such as liquid oil and fat.
It is used as a paste by adding ~10% of it, but when storing it, you can store it in a solidified state without adding a spreading agent and crush it at the time of processing and add a spreading agent, or you can add a spreading agent during production. It may also be stored as a paste by adding an agent.

Next, the reason for limiting the mixing ratio of the components of the repair agent of the present invention will be explained.

If the content of metallic zinc powder exceeds 50%, the hot water flow temperature will become high, causing local oxidation of the pre-formed coating and even melting of the pre-formed coating. If the amount of metallic tin powder is increased to less than 30%, the melt flow temperature will be lowered, but many pits will be formed in the coating layer, causing rust, and a sufficient coating effect will not be obtained.

Therefore, the content of metal zinc powder was limited to 30 to 50%.

If the content of metallic tin powder exceeds 20%, the melt flow temperature will be lowered for the same reason as described above, but many pits will occur in the coating layer, causing rust, and a sufficient coating effect will not be obtained.

Moreover, if the metallic tin powder is less than 10%, the melt flow temperature will become too high, and oxidized portions will occur in the already formed film.

For this reason, the content of metallic tin powder was limited to 10 to 20%.

Ammonium chloride, zinc chloride, or tin chloride are added as solvents to reduce oxides during metal dissolution, remove toxic gases, cover the hot water surface to prevent oxidation, and promote slag removal. Although it is originally not necessary to limit the content, the content was limited for the following reasons.

That is, when ammonium chloride and zinc chloride or tin chloride are combined in an amount to provide a flux effect to the above-mentioned 30 to 50% zinc metal powder and 10 to 20% metal tin powder, the required lower limit amount is chloride. 20% for ammonium and 15% for zinc chloride or tin chloride.

However, increasing these amounts would be economically expensive, so the upper limit was set at 30% for ammonium chloride and 25% for zinc chloride or tin chloride.

Regarding the spreading agent, for example, when adding liquid oil, if the content exceeds 10%, the carbide of the oil and fat component will be generated as soot during heating, impeding workability, and if it is less than 5%, it will become a hard flux. It becomes difficult to apply and the shelf life is shortened, so limit the amount to 5 to 10%. If alcohol or water is added, if it exceeds 10%, a large amount of steam will be generated during heating, which will hinder workability. However, alcohol in particular has a strong odor that further impedes workability.

If the amount is less than 5%, the repair agent becomes too hard, making it difficult to apply to the defect, and spontaneous evaporation is intense, making it unusable if the time from addition to application to the defect is extremely short.

Further, for the same reason as above, the amount of spreading agents other than these was limited to 5 to 10%.

In addition, in the present invention, in particular, 30 to 50% of metal zinc powder,
35 to 55% of a mixture of zinc chloride and ammonium chloride mixed in advance at a ratio of 1:1 to 1:3 is added to a mixture of 10 to 20% of metal tin powder, and then mixed.
It was found that the repair agent prepared by adding 10% liquid fat has less hygroscopicity and has a longer shelf life.

Next, examples of the repair agent of the present invention will be described with reference to the drawings.

Example ■ Figure 1 shows a state in which a galvanized flange is arc welded to the gas-cut end of a sacrificial carbon steel pipe that has been galvanized by immersing it in a molten zinc bath. 1 is a steel pipe, and 2 is a steel pipe. 1 is an arc welded flange, 3 is a zinc coating coated on the surface of the steel pipe 10, 4 is a zinc coating coated on the flange 20 surface, 5 and 6 are front and back welded parts of steel 1 and flange 2, 7a and 7b is a burnt out part of the zinc coating of the steel pipe 1 caused by gas cutting and welding, and 8a and 8b are burnt out parts of the zinc coating of the flange 2 caused by welding.

First, for such a member, the burnt part 7a of the steel pipe 1,
7b and the surfaces of the burnt parts 8a and 8b of the flange 2 and the surfaces of the welded parts 5 and 6 are rubbed with a wire brush to remove dirt and oxides, and the repair agent of the present invention having the following components is applied. and heated with an oxygen/acetylene flame.

The repair agent of this example was produced by the method of the present invention.

That is, 210 g of zinc chloride and 220 g of ammonium chloride were thoroughly stirred in a mortar, and in another mortar, 380 g of 200 mesh metal zinc powder and 140 g of 200 mesh metal tin powder were mixed.
were thoroughly stirred and mixed.

Furthermore, a mixture of zinc chloride and ammonium chloride 430
g and 520 g of a mixture of metallic zinc powder and metallic tin powder
were mixed and thoroughly stirred to completely mix the mixture, and when the mixture was completely mixed, 50 g of linseed oil was added little by little while stirring to produce a paste-like repair agent.

When coating the burnt parts 7a, 7b, 8a, and 8b with this repair agent, the temperature is raised to 300 to 320 DEG C. by gradually bringing the flame closer so that the applied material is not blown away by the pressure of the acid/acetylene flame.

The powders of metallic tin and zinc are burnt out in the burnt parts 7a, 7b and 8a, 8 due to the flux effect of ammonium chloride and zinc chloride.
(b) Furthermore, the zinc coatings 3 and 4 remaining on the steel pipe 1 and flange 2 are also welded together with the welded parts 5 and 6, forming a repair coating with strong adhesive strength and good corrosion resistance, and the burnt part is completely removed. coated.

FIG. 2 shows the situation after the burnt out parts 7a, 7b and 8a, 8b of the zinc coating and the welded parts 5, 6 shown in FIG. 1 have been repaired using the repair agent of the present invention. Uniform repair coatings 9a and 9b were formed on the surfaces of at7b and 8a+8b and the welded parts 5 and 60, as well as on the other parts that were not burnt out.

Example 1 Next, a repair agent of the present invention having a component composition was manufactured by a method other than the method of the present invention.

That is, 200 g of metal tin powder and 220 g of ammonium chloride are added to 300 g of metal zinc powder and stirred thoroughly to mix completely.

Next, 200 g of tin chloride was added to the mixture while being careful not to deliquesce, and stirred to form a mixture, and 80 g of tin chloride was added to this mixture.
Hempseed oil was added little by little and stirred to produce a paste-like repair agent.

This repair agent was welded to the burnt area using an oxygen/acetylene flame in the same manner as in Example 1 at a heating temperature of 270 to 290°C to form a uniform zinc coating with good adhesion.

Comparative Example A product was prepared by mixing the components having the above compositions in the following manner.

That is, 80 g of metallic tin powder and 150 g of ammonium chloride are added to 520 g of metallic zinc powder and thoroughly stirred to mix completely.

Next, add 200g of zinc chloride, being careful not to deliquesce.
was added to the mixture and stirred to form a mixture, and 50
g of tung oil was added little by little while stirring to produce a paste-like repair agent.

To cover the burnt area with this repair agent, 400'C
It turned out that plating was difficult unless heated to
In addition, oxidized portions were locally generated in the existing coating.

In the case of Examples ① and ②, it was possible to form a zinc film using water or alcohol such as linseed oil or hempseed oil, but when stored for a long time, chloride as a flux component It may be difficult to disassemble and use.

As detailed above, according to the present invention, when repairing defective parts of zinc coating, it is possible to form a strong repair coating in an extremely short time compared to repair methods such as painting with zinc paint, which is extremely useful industrially. It is.

[Brief explanation of the drawings] Figure 1 is a vertical sectional view showing the upper half of a sacrificial carbon steel pipe with a flange welded to the gas-cut end, and Figure 2 is the end of the steel pipe shown in Figure 1. FIG. 3 is a longitudinal cross-sectional view of the upper half of the vehicle after the repair agent of the present invention has been repaired. 1... Steel pipe, 2... Flange, 3, 4
...Zinc coating, 5,6...Welded part, 7
a t 7b t 8a j8b-... Burnt part of zinc coating, 9a t 9b... Repair coating.

Claims (1)

[Claims] 1. Metallic zinc powder 30-50% by weight, metallic tin powder 1.
Zinc containing 0 to 20% ammonium chloride, 20 to 30% ammonium chloride, and 15 to 25% zinc chloride or tin chloride, and made into a paste by adding 5 to 10% of a spreading agent such as liquid oil or fat. A repair agent for coating defects. 2 30-50% by weight of metallic zinc powder and 10-50% by weight of metallic tin powder
20% by weight, and a mixture of ammonium chloride and zinc chloride or tin chloride 35-5
A zinc coating defect repairing agent characterized in that 5% by weight is prepared in advance, and a mixture of these two types and 5 to 10% by weight of a spreading agent such as liquid oil and fat are uniformly mixed and used as a paste. Production method.