KR20170025260A - Hot dip galvanizing bath composition for parkerizing - Google Patents

Abstract

The present invention relates to a hot dip galvanizing bath composition for parkerizing, comprising: 0.5-2.0 wt% of manganese, 0.001-0.01 wt% of aluminum, 0.001-0.01 wt% of palladium, and the remainder being zinc base. Accordingly, there is an effect of improving durability by preventing a coat from easily being dropped off due to a weak adhesive force at the time of coating on an upper part of hot dip galvanize in a pipe plating of a system mounted on a ship.

Description

Technical Field The present invention relates to a hot dip galvanizing bath composition for parkerizing,

The present invention relates to a hot-dip galvanizing bath composition, and more particularly, to a hot-dip galvanizing bath composition for a plated surface phosphate coating that prevents a coating from being easily detached due to a weak adhesion at the time of hot-dip galvanizing.

In general coating (coating) method, the surface is subjected to blasting or primer painting, and then the upper coating is applied. However, since the adhesion is weak, the application range is limited to those fields that do not require durability.

For example, the following Prior Art 1 discloses a method of coating a metal base material of a magnesium alloy or an aluminum alloy, comprising the steps of pretreating a surface of a metal base of a magnesium alloy or an aluminum alloy, washing the metal base, And a step of electrodepositing the substrate, wherein the water washing step and the electrodeposition painting step are continuously performed. Thus, the process time can be shortened by simplifying the number of process steps, and the coating failure rate is low, thereby reducing the overall process cost.

However, phosphate coatings are preferred in metal (mainly steel) pipes that are periodically replaced while mounted on various systems of the ship. The phosphate coating chemically reacts the metal with dilute phosphoric acid to produce the surface of the metal as a poorly soluble crystalline phosphate, which is used for coloring and rust prevention of ships, automobiles, transformers and the like. However, in order to form a phosphate coating on the hot-dip galvanized surface, it is necessary to increase the surface roughness by sandpaper or the like, so that the air quality is increased, but it is difficult to maintain the coating quality corresponding to seawater.

In the following Prior Art 2, the zinc ion concentration and the chloride ion concentration were controlled so that the pH of the plating solution was adjusted to a range of 2.0 to 6.0, the temperature of the plating solution was maintained in a range of 40 to 70 ° C, / dm < ^{2 >} and a relative flow rate of 0.5-3.0 m / sec. Thus, it is expected that the surface appearance, whiteness and gloss of the zinc plated layer are good under a wide range of electrolytic conditions, and that the surface appearance after the phosphate treatment is excellent.

However, since the prior art 2 described above is aimed at improving the appearance of the steel plate with respect to the steel material, it is difficult to apply it to plating and coating of pipes constituting various systems of a ship.

1. Korean Patent Laid-Open Publication No. 2009-0075362, "Metallic coating method and parts painted by the method" 2. Korean Patent Registration No. 0143502 entitled " Method for manufacturing galvanized steel sheet having excellent plating appearance and phosphate treatment property "(Publication date: May 22, 1996).

It is an object of the present invention to overcome the above-mentioned problems of the prior art by providing a plating surface phosphate coating To provide a hot-dip galvanizing bath composition for use in a hot-dip galvanizing bath.

In order to achieve the above object, the present invention provides a hot dip galvanizing bath composition for a phosphate coating on a plated surface, comprising: 0.5 to 2.0 wt% of manganese, 0.001 to 0.01 wt% of aluminum and 0.001 to 0.01 wt% of palladium And the remainder is made of a base material of zinc.

As a detailed constitution of the present invention, the zinc base material is characterized by being used at a high purity of not more than 2.0 wt% of Fe, not more than 0.2 wt% of Pb and not more than 0.05 wt% of Cd, which deteriorates the plating quality of the steel pipe.

As a detailed constitution of the present invention, the zinc base material is characterized by further containing a component selected from Ti, Ni and Mo so as to improve the mechanical properties of the steel pipe to the plated coating.

As described above, according to the present invention, it is possible to prevent the phenomenon that the paint is easily dropped off due to the weak adhesive force at the time of coating on the hot dip galvanizing in the pipe plating of the system mounted on the ship, thereby improving durability.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention proposes a hot dip galvanizing bath composition for a phosphate coating on a plated surface. The present invention is not limited to steel pipes, which are pipes such as process processing and water treatment systems mounted on ships. The optimum method for increasing the adhesion of the coating to the upper part of the hot-dip galvanized layer is to increase the adhesion of the coating with the optimum plating bath composition since it is not easy to form the phosphate coating and then the upper coating and the formation of the phosphate coating on the hot-dip galvanized layer. .

The hot dip galvanizing bath according to the present invention is characterized in that it contains 0.5 to 2.0 wt% of manganese, 0.001 to 0.01 wt% of aluminum, 0.001 to 0.01 wt% of palladium, and the balance of zinc base material. Hot dip galvanizing is a zinc anode sacrificial anodizing action, which delays the corrosion of steel pipes in a typical water environment, which is particularly advantageous for reducing maintenance costs in piping of large ships. Main content of zinc is 97.99 ~ 99.48wt%, and manganese, aluminum and palladium are included as auxiliary components.

Manganese breaks the surface oxide film and improves the corrosion resistance, while improving the workability by lowering the melting point. Manganese is a component that increases the strength and toughness of carbon steel and is included in the steel pipe material. The manganese in the plating bath improves the electrodeposition resistance of the steel pipe, but if it exceeds the proper range, the weldability and workability of the steel pipe deteriorate.

Aluminum improves the flowability of the hot dip galvanizing bath and also creates an oxide film on the surface to inhibit the reaction. Aluminum in the plating bath is distributed to a certain depth on the surface of the plating layer to increase the peeling resistance. If the content of aluminum exceeds the proper range, a non-plating state due to an oxide is likely to occur. In this case, the atmosphere should be controlled so that no oxide is formed on the surface of the steel pipe and the surface of the hot-dip galvanizing bath.

Palladium activates the surface of the plated layer and acts as a nucleation point of the phosphate coating. Palladium is relatively thin and exhibits excellent corrosion resistance and high hardness. Palladium is a noble metal that is inexpensive compared to gold, but it is preferable that palladium does not exceed an appropriate range in terms of economy.

As a detailed constitution of the present invention, the zinc base material is characterized by being used at a high purity of not more than 2.0 wt% of Fe, not more than 0.2 wt% of Pb and not more than 0.05 wt% of Cd, which deteriorates the plating quality of the steel pipe. Fe may be eluted from the surface of the steel pipe during the plating process, and if it exceeds the proper range, it forms a debris with a compound of zinc to reduce ductility and adhesion. In case of Pb and Cd too, exceeding the proper range content is a component which deteriorates the plating quality and is environmentally harmful and should be limited. When the purity of the zinc base material is increased by restricting Fe, Pb and Cd which are impurities of the steel pipe plating layer, peeling of the plating layer can be suppressed and the workability in welding and flare treatment of the steel pipe can be improved.

As a detailed constitution of the present invention, the zinc base material is characterized by further containing a component selected from Ti, Ni and Mo so as to improve the mechanical properties of the steel pipe to the plated coating. When Ti, Ni, and Mo are added to the plating bath in a small amount, adhesion of the zinc plating layer to the surface of the steel pipe can be improved. Ti can increase the strength and toughness to improve the plastic workability, Ni can suppress the deterioration in the hot working process, and Mo can improve the strength and alleviate the crack in the plastic working process. The content of Ti, Ni, and Mo in the zinc base material is maintained in the range of 0.01 to 0.1 wt%, respectively.

In the experiment of the present invention, hot-dip galvanizing bath specimens were prepared by varying the contents of manganese, aluminum and palladium in addition to the test specimens of carbon steel tubes. The hot-dip galvanizing bath specimens were pickled and washed with hot zinc plating, , And top coating are sequentially processed. After that, welding process, flare process, bending process is applied to the specimen, and then the state of the coating is visually observed and the equipment is judged.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined by the appended claims. It is therefore intended that such variations and modifications fall within the scope of the appended claims.

Claims (3)

A hot dip galvanizing bath composition for a phosphate coating on a plating surface comprising:
A hot-dip galvanizing bath composition for a plated surface phosphate coating, which comprises 0.5 to 2.0 wt% of manganese, 0.001 to 0.01 wt% of aluminum, 0.001 to 0.01 wt% of palladium, and the balance of zinc base. The method according to claim 1,
Wherein the zinc substrate is used in a high purity of not more than 2.0 wt% of Fe, not more than 0.2 wt% of Pb, and not more than 0.05 wt% of Cd, which deteriorates the plating quality of the steel pipe. Composition. The method according to claim 1,
Wherein the zinc substrate further contains a component selected from Ti, Ni, and Mo to improve the mechanical properties of the steel pipe to the plating film.