JPH1030161A - Hot dip galvanizing equipment and method for adding titanium to this equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the consumption of titanium and the formation of surface oxidized film by partitioning a part of a zinc bath and adding a master alloy for plating therein. SOLUTION: In this equipment, a part of a hot-dip zinc bath 11 is provided with a partition board 13 limiting a titanium adding region. Thus, as for the formation of surface oxide to accompany the oxidation of titanium, it is partitioned from a steel sheet 12 pulled up from plating, so that its adhesion to the surface of the steel sheet 12 as the material to be plated can be stopped to the minimum. Then, since titanium is not added at a time, and also, the adding region thereof is locally limited, the amt. of titanium to be added is regulated to the minimum limit, and, as a result, its consumption is made to be the minimum limit as well. Furthermore, for preventing the contact of titanium oxidized film with the steel sheet 12, the width between an inner frame 14 and the steel sheet 12 may be narrowed. In the addition of titanium, for obtaining a good product, a master alloy for plating not containing the ones high in a titanium ratio such as metallic Ti, Zn Ti or the like is preferably used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot-dip galvanizing apparatus for adding titanium to obtain high corrosion resistance in hot-dip galvanizing, and a method for adding titanium to a zinc bath of the apparatus.

[0002]

2. Description of the Related Art In recent years,
In hot-dip galvanizing, further improvement in corrosion resistance is demanded, but addition of titanium is being studied as high corrosion-resistant plating. In general, for such alloying, a method is used in which zinc base metal alloyed to a predetermined concentration in advance is used, and when a bath composition fluctuates during plating, a high-concentration master alloy is appropriately added.

[0003] However, in the addition of titanium,
Since titanium has a higher melting point than zinc, it is naturally lightweight and easily oxidized, so that there is a problem that alloying is difficult first and the cost of alloying is high.

[0004] Further, in a zinc bath containing titanium, there is a problem that titanium is constantly oxidized and floated and is consumed, and a blue oxide film is formed on the surface and adheres to a plating object. As a result, although the effect of titanium addition on the improvement of corrosion resistance has been recognized, it has not been widely used at present.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a hot-dip galvanizing apparatus and a method for adding titanium to the apparatus, which suppresses the consumption of titanium and the formation of a surface oxide film when adding titanium to zinc plating. And

[0006]

The present inventors have conducted various studies to solve the above-mentioned problems, and as a result, by adding a titanium master alloy enriched with titanium in zinc immediately before pulling up the plating, The present inventors have found that the amount of consumption of the resin can be minimized, and completed the present invention.

The hot-dip galvanizing apparatus according to the present invention based on the above knowledge is a hot-dip galvanizing apparatus in which titanium is added to a hot-dip galvanizing bath. , And a plating master alloy is disposed in the frame of the partition plate.

On the other hand, a method of adding titanium to a hot dip galvanizing apparatus is a method of adding titanium to a hot dip galvanizing bath, in which a part of the zinc bath of the hot dip galvanizing apparatus is partitioned using a partition plate. And a plating master alloy added in the frame of the partition plate.

In the above method of adding titanium, the master alloy for plating is a zinc-titanium alloy containing no intermetallic compound of Zn ₂ Ti, ZnTi, ZnTi ₂ and a metal Ti layer.

[0010]

Embodiments of the present invention will be described below.

An embodiment of the present invention will be schematically described with reference to FIGS. This apparatus is provided in a portion of a zinc crucible (not shown) where a steel plate 12 as a plating material of a zinc bath 11 is plated. As shown in FIG. 1 and FIG. 2, the present apparatus is a rectangular iron partition plate 1 for partitioning a zinc bath for plating a steel plate 12 pulled up in a vertical direction.
3 and an iron inner frame 1 provided inside the partition plate 13
The plating alloy 15 is provided between the partition plate 13 and the inner frame 14.

According to the above-mentioned apparatus, since the partition plate 13 for limiting the titanium-added region is provided in a part of the molten zinc bath 11, the generation of the surface oxide accompanying the oxidation of titanium is different from that of the steel plate 12 pulled up by plating. Since it is partitioned, it can also be minimized to adhere to the surface of the steel plate 12 which is the object to be plated. On the other hand, a large amount of molten zinc is generally held in a plating bath with a large surface area. Therefore, when titanium is added to the entire molten metal as in the related art, the amount of titanium added is large, and The surface area to be oxidized is large, and the consumption is remarkable.

In this method, titanium is not added all at once, and the region where titanium is added is limited to a local area. Therefore, the amount of titanium added is minimized, and consequently the consumption thereof is also minimized.

In order to prevent the titanium oxide film from coming into contact with the steel sheet 12, the width between the inner frame 14 and the steel sheet 12 to be pulled up may be reduced. Alternatively, for example, the shape of the inner frame 14 may be L-shaped by extending downward along the zinc-titanium master alloy and bending the lower end portion inward (see FIG. 3).

In the present invention, the shape of the zinc-titanium master alloy 15 may be a rod as shown in FIG. When there is a spatial limitation, a block shape, a spherical shape, or a linear shape may be appropriately selected.

In addition, when such titanium is added, a compound having a high titanium ratio, such as titanium metal, Zn ₂ Ti, ZnTi, ZnTi ₂ , is formed and does not dissolve in the zinc bath but adheres to the plating surface as it is. In some cases, product failure was caused. Since the method of the present invention is a method in which the melting time of titanium is short, it is necessary to use a master alloy which does not particularly contain such a compound having a high titanium ratio also in the titanium master alloy. Such a method for producing a zinc-titanium master alloy (titanium content of 5% by weight or less) can be obtained by, for example, using titanium sponge as a raw material and maintaining the material at 500 to 750 ° C for 30 minutes to 6 hours.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.
The present invention is not limited to this.

FIG. 3 is a schematic diagram of an apparatus according to the present embodiment. In the figure, reference numeral 11 denotes a zinc bath, 12 denotes a steel plate, 13 denotes a partition plate, 14 denotes an inner frame, 15 denotes a zinc-titanium master alloy, and 16 denotes a titanium pipe coating. The unit in the figure is mm. In this embodiment, the shape of the inner frame 14 is extended downward along the zinc-titanium master alloy, and the lower end is L-shaped inward. This is the steel plate 1 to be plated.
This is for preventing the titanium oxide film from coming up and coming into contact with the steel sheet 12 with respect to the steel sheet 12.

In a 200 # graphite crucible, a zinc-titanium master alloy 15 was disposed in a partition plate 13 as shown in FIG. 3 to provide a titanium addition portion, and 5% by weight of a titanium master alloy was added.
In the present example, the zinc-titanium master alloy 15 was made of titanium sponge as a raw material, alloyed in a pure zinc melt by holding at 650 ° C. for 1 hour, and formed into a rod having a diameter of 20 mm. The zinc-titanium master alloy 15 was added as shown in FIG. 3, and the surface of the plated portion was observed and the titanium concentration of the molten metal in the plated portion was analyzed.

After titanium was added for 5 minutes, the oxide film on the surface of the plated portion was slightly pale blue, and the titanium concentration at the analysis point X in FIG. 2 was about 0.13%.
The titanium concentration can be controlled by adjusting the titanium pipe coating 16 that coats the zinc-titanium master alloy 15 to adjust the exposed area.

[0021]

As described above, as described with the embodiment,
According to the present invention, it is possible to overcome the problems of the conventional addition method, whereby titanium can be efficiently added and the zinc plating can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic front view of a hot dip galvanizing apparatus.

FIG. 2 is a schematic plan view of a hot dip galvanizing apparatus.

FIG. 3 is a schematic diagram of a hot-dip galvanizing apparatus according to an example.

[Explanation of symbols]

 11 Zinc 1 is a steel plate 13 Partition plate 14 Inner frame 15 Zinc-titanium master alloy 16 Titanium pipe coating

Claims (3)

[Claims] 1. A hot-dip galvanizing apparatus in which titanium is added to a hot-dip galvanizing bath, wherein a part of the zinc bath is partitioned by using a partition plate having an opening for lifting a plate to be plated therein. A hot-dip galvanizing apparatus characterized in that a plating master alloy is disposed in the frame of (1). 2. A method for adding titanium to a hot-dip galvanizing bath, comprising a step of partitioning a part of a zinc bath of a hot-dip galvanizing apparatus using a partition plate, and forming a plating base within a frame of the partition plate. A method for adding titanium, comprising adding an alloy. 3. The method for adding titanium according to claim 2, wherein the mother alloy for plating is Zn ₂ Ti, ZnTi, ZnTi.
_2. A method for adding titanium, which is a zinc-titanium alloy containing no intermetallic compound and no metal Ti layer.