JPS61213389A - Electroplating device by molten salt bath - Google Patents

Abstract

PURPOSE:To prevent the carrying of moisture into a system and carrying of a molten salt out of the system by providing vessels for a liquid metal which does not stick to a material before and behind a molten salt bath cell, executing plating of the material via such liquid metal and maintaining airtightly the bath cell. CONSTITUTION:A steel strip 1 is passed by a deflecting roll 10 into the liquid metal which does not stick to the strip 1 in the inlet side vessel 9 and is introduced by conductor rolls 4 and sink rolls 3 into the molten salt bath cell 2. The strip 1 is passed between anodes 5 and is thus electroplated. The plated strip is then passed by a direction changing roll 13 into the liquid metal which does not stick to the strip 1 in the outlet side vessel 11. The liquid metal having the specific gravity heavier than the specific gravity of the molten salt is used for the liquid metal in the vessels 9, 11 and Pb, Pb alloy are more preferable. The terminal of a cover 6 of the cell 2 is immersed into the liquid metal in the vessels 9, 13 to provide liquid sealing, by which the inside of the system is airtightly maintained.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention uses a molten salt bath to produce steel strips or wire rods.
This invention relates to an apparatus for continuously plating T* etc. by electrodeposition.

[Conventional technology]

M-plated steel has many advantages, such as being beautiful, non-toxic, and has excellent corrosion resistance. In addition, Ti-plated steel has excellent acid resistance, alkali resistance, and heat resistance.
There are many advantages. Among these, M-plated steel materials were mostly manufactured by the molten metal dipping method. However, with this method, it is difficult to thin the material, and the operating temperature is high, at 700° C. or higher (the heat causes the formation of an alloy layer and adversely affects the base material).

The main reason why the molten metal immersion method is used for M plating is
M is in that electrodeposition from an aqueous solution is impossible. However, as mentioned above, the molten metal immersion method has many problems.
There are great expectations for the practical application of electroplating as an alternative to this.

Kinman, which cannot be deposited from an aqueous solution, such as M%Ti,
However, electrodeposition can be performed using a non-aqueous solvent bath or a molten salt bath. Non-aqueous solvent baths generally have a high resistivity and are flammable, so they are unsuitable for large-scale plating. On the other hand, molten salt baths are suitable for large-scale processing, but salts such as anhydrous aluminum chloride or anhydrous titanium chloride used as bath components are highly hygroscopic, and IJ! s Plating metals such as Tl also have a strong affinity for oxygen, and complete plating cannot be performed in the presence of moisture or oxygen. For this reason, even when looking at proposals for electroplating using a molten salt bath, it is customary to introduce an inert gas into the system to isolate the system from the atmosphere.

[Problem that the invention seeks to solve]

However, even with such consideration, when continuously plating steel strips or wire rods, it is extremely difficult to maintain airtightness on the input and output sides of the material. In addition, on the input side, after pre-treating the material, care must be taken to dry the surface sufficiently to prevent moisture from being brought into the system, and on the output side, care must be taken to prevent moisture from being brought into the system by adhering to the material and leaving the system. It is necessary to minimize the amount of molten salt taken out.

Conventionally, these 7 baths were carried out using rolls, but the airtightness was poor and it was impossible to sufficiently reduce the amount of molten salt carried out of the system. Since the temperature is usually 200° C. or higher and highly corrosive salt is used, there has been a major problem in the durability of the rolls.

An object of the present invention is to provide a molten salt bath that can improve the airtightness of the system without using seals with rolls, and can minimize the amount of moisture brought into the system and the amount of molten salt taken out of the system. The purpose of the present invention is to provide a continuous electroplating device using the following methods.

[Means for solving problems]

The electroplating apparatus of the present invention covers a molten salt bath, fills the inside with an inert gas or a reducing gas, and continuously electroplates a steel strip or wire. A liquid metal container that does not adhere to the material is provided on both sides, and the material is configured to pass through the liquid metal, and the end of the cover of the molten salt bath is immersed in the liquid metal, so that the interior of the cover is It is characterized by liquid sealing on the material input side, the material output side, or both.

Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1 is a longitudinal sectional side view showing the structure of an example of an electroplating apparatus embodying the present invention.

In the figure, (1) is a steel strip which is a material to be plated, and (2) is a molten salt bath (hereinafter simply referred to as a bath). A plurality of zinc rolls +31 +31 are provided in the tank (2).
) Multiple conductor rolls provided above (4) (4)
<4), the steel strip (1) advances while changing direction in the vertical direction. Inside the tank (2), there are also anodes (5) sandwiching the traveling path of the steel strip (11) from both sides.
...(5) is provided. The anode (5) may be insoluble or soluble.

As the molten salt, when the steel strip (1) is M, )JJ3-T
J (X: alkali metal) mixed molten salt, etc., such as Ti mino, Ticea-BaCe2-MgCe2-Ωtsu2
-N1ce etc.

(6) is a cover that covers the tank (2), and is equipped with an inert gas or reducing gas inlet pipe (7) and outlet pipe (8) on the top plate. Examples of the inert gas include argon gas and nitrogen gas, and examples of the reducing gas include hydrogen gas.

A liquid metal container (9) is attached to the inlet side of the steel strip (1) in the tank (2), and the steel strip (1) that has progressed horizontally toward the container (9) is passed through a plurality of turning rolls. After being guided by α(1(lαα) and entering the container (9), it is configured to enter the tank (2) via the first stage conductor roll (4).

The wall of the cover (6) on the inlet side of the steel strip (1) is inserted into the container (9) from above, and its lower end is immersed in the liquid metal in the container (9). Needless to say, care is taken to prevent the steel strip (1) and the wall from interfering within the container (9).

Similarly, a liquid metal container αυ is attached to the outlet side of the steel strip (1) of the tank (2), and a weir O is provided between the tank (2) and the container αD.
It has a structure divided into 2 sections. This part is provided with a plurality of turning rolls 03 Gm (13), a cover (
The lower end of the wall on the outlet side of the steel strip (1) in 6) is immersed in the liquid metal in the container aD.
).

Both sides of the device (front and opposite sides of the drawing) are the tanks (2)
, a structure in which the container (91 (In) and the cover (6) are hermetically joined.

The liquid metal in the container (9) aD must not adhere to the steel strip (1) before or after plating. As such a liquid metal, Pb (melting point: 327°C,
specific gravity 10), Pb-8b (252-630°C, 7-10
)Ag-Pb (304-960℃, 9.3-10.0
)*Ag-8n (221-960℃, 6.8-9.3
), Bi-Pb (125-327°C, 10)
, 1Bb, knee 5n (187-327℃, 6.8-10
．． 0) etc. In addition, the container αD on the outlet side of the steel strip (1)
It is necessary for the liquid metal placed in the tank (2) to have a higher specific gravity than the molten salt bath in the tank (2). Incidentally, all of the above-mentioned liquid metals such as Pb and Pb alloys satisfy this condition. The temperature of the liquid metal is usually controlled around the operating temperature of the molten salt bath. It goes without saying that when selecting a liquid metal, it is necessary to choose one that has a melting point below this control temperature. There is no problem in changing the type and temperature of the liquid metal between the container (9) and the circle.

The size of the container +91 Qll is the width of the steel band (
It needs to be wider than 1). For other dimensions, the depth, more specifically the depth of immersion of the steel strip (1) into the liquid metal, is important. That is, approximately 2 of this immersion depth d
Multiplied by the distance the steel strip (1) passes through the liquid metal, the time for the steel strip (1) to pass through the liquid metal is determined from the passing distance and the moving speed v4/sec) of the steel strip (1). Then, from the passage distance or passage time, the moisture removal capacity (described later) of the inlet side container (9), and the molten salt removal capacity, also described later, of the outlet side container αD are determined. . Taking these into consideration, the immersion depth A is usually d>0.1v1 on the entry side.
It is preferable that d>0.2v on the output side. Although there are no particular restrictions on other dimensions, it is not only meaningless that the capacity of the container (91 (111) is too large, but also deteriorates economic efficiency.

In addition, in this specification, the system refers to a part that is placed under an inert gas or reducing gas atmosphere, including a molten salt bath.

The functions and effects of the electroplating apparatus having the above configuration are as follows.

To pass the steel strip (1) through the device, open the inlet pipe (7) and outlet pipe (8) attached to the cover (6), and inject inert gas or reducing gas into the cover (6) from the inlet pipe (7). When the gases are introduced and the system is replaced with these gases, the outlet pipe (7) is closed, and the inlet pipe (6) is slightly inserted to maintain the pressure in the system about 5% higher than atmospheric pressure. At the entrance and exit sides of the steel strip (1), the lower end of the cover (6) is connected to the container (9).
(Because it is immersed in the liquid metal in the In, the gas inside the system hardly leaks out of the system, and not only is the system maintained in a good non-oxidizing atmosphere, but the amount of gas replenishment is also reduced. It is reduced to a large extent.

In electroplating, the steel strip (1), which has undergone pretreatments such as degreasing and pickling, is dried and enters the liquid metal in the container (9). The steel strip (1) that has passed through the liquid metal passes through the molten salt bath in the tank (2) multiple times, during which time electricity is passed between the anode (5), the steel strip (1), and the conductor roll (4). The plating metal in the molten salt bath is electrodeposited on the surface of the steel strip (1), but since the liquid metal used is a metal that does not adhere to the steel strip (1), the electroplating is difficult. Not only does it not become an obstacle during drying, but the steel strip (1) is not sufficiently dried.

Even if the steel strip (1) passes through the liquid metal, moisture on the surface is removed, and moisture is prevented from being carried into the tank (2). In electroplating using a molten salt bath, the molten salt has strong heat absorption properties, and it is important to avoid moisture from entering the molten salt bath as much as possible. It is also extremely effective in preventing deterioration.

The steel strip (1) that has finished electrodeposition in the tank (2) enters the liquid metal in the container αD on the outlet side again. It adheres to the steel strip (1) and forms a tank (
2) The molten salt carried out is removed while passing through this liquid metal. Since the liquid metal has a higher specific gravity than the molten salt, the molten salt removed from the steel strip (1) accumulates above the liquid metal in the container surface, and when it exceeds a certain amount, it exceeds the weir α2 and flows into the tank (2). It is possible to prevent the waste from being refluxed and taken out of the system, and to save time and effort for collection.

The steel strip (1) (plated steel strip) that has exited the container αD is wound into a coil after undergoing processes such as washing and drying.

An experimental device for the electroplating device described above was constructed, and an endless coil was continuously passed through it to examine its effects. The experimental conditions are shown in the table. Pre-treatment of the steel strip includes N2 after pickling.
Drying and preheating were performed in an air stream.

6 each at various speeds within the range of 1 to 50 rrL/min.
Continuous plating was carried out for several hours, but no deterioration of the molten salt bath was observed in any case, and no moisture or chips entered the system.
No leakage of steam to the outside of the system was detected.

In addition, in the electroplating apparatus shown in Fig. 1, liquid metal containers are provided on the inlet and outlet sides of the steel strip (1), but either one may be omitted, and in that case, the container on the remaining side is Appropriate effects can be obtained.

As the material to be plated, although the case of steel strip is shown, it goes without saying that wire rod can also be applied.

Typical plating metals are A/ and Ti, but any metal may be used as long as it requires the use of a molten salt bath in an inert gas or reducing gas atmosphere.

〔Effect of the invention〕

As is clear from the above description, the electroplating apparatus using a molten salt bath of the present invention is provided with a liquid sealing mechanism using liquid metal on the entrance side to the bathtub, the exit side from the bathtub, or both. This not only improves the airtightness of the system and maintains a non-oxidizing atmosphere within the system, reducing the amount of non-oxidizing gas supplied into the system, but also prevents moisture from entering the system along with the material if it is installed on the inlet side. This prevents the molten salt from entering the system, thereby suppressing bath deterioration as much as possible, and when it is provided on the outlet side, it prevents the molten salt from being taken out of the system together with the material, resulting in excellent economic efficiency.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view showing the structure of an example of an electroplating apparatus embodying the present invention.

Claims (2)

[Claims] (1) In an apparatus that covers a molten salt bath and fills the inside with an inert gas or reducing gas to continuously electroplate steel strips or wire rods, the A container for liquid metal that does not adhere to the material is provided, and the material is configured to pass through the liquid metal, and the end of the cover of the molten salt bath is immersed in the liquid metal, so that the material enters the inside of the cover. Or an electroplating device using a molten salt bath, characterized in that the exit side or both sides are liquid-sealed. (2) The liquid metal container located at least on the material outlet side is connected to the molten salt bath via a weir, and the liquid metal in the container has a higher specific gravity than the molten salt bath. An electroplating device using a molten salt bath according to item 1.