JPH0811837B2 - Molten salt electrolytic plating method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a method for electroplating a steel material using a molten salt as a plating bath solution.

[Conventional technology]

Conventionally, for example, molten salt aluminum electrolytic plating has been known as a method for plating a steel material, but it has hardly been put to practical use. One reason is that no suitable means for activating the surface of steel has been developed.

In the conventional aqueous solution electroplating method, the surface of the steel material is activated by pretreatment such as degreasing, pickling, and water washing before plating, but in the molten salt electroplating, sufficient drying after water washing is required. The final drying is to prevent the aluminum chloride-based mixed molten salt, which is the plating bath liquid, from deteriorating due to moisture, but this treatment oxidizes the steel material and forms an oxide film, which causes plating. There was a problem that the adhesiveness of was damaged.

This problem is a method previously proposed by the present applicants, that is, melting of a steel material characterized by anodic dissolution treatment of the steel material prior to electroplating the steel material to activate the steel surface. It has been solved by a salt electrolytic plating method. [Refer to JP-A-63-143282] [Problems to be solved by the invention] However, in the above-mentioned proposed method, the iron content eluted in the molten salt bath solution by the anodic dissolution of the steel material is converted into iron ions to form the bath solution. The bath solution containing the iron ions is deposited on the steel material and brought into the molten salt bath solution in the plating tank to increase the iron ions in the plating bath solution. If the amount increases, iron is mixed into the plated coating on the steel material, which deteriorates the quality of the plated coating.

[Object of the Invention]

The present invention is intended to provide a molten salt electrolytic plating method capable of solving the above-mentioned drawbacks of the previously proposed method.

[Means for solving problems]

The present invention is a method of anodic dissolution of a steel material in a method of anodic dissolution of a steel material in a molten salt bath liquid of an anodic dissolution tank, activating its surface, and then transferring the steel material to a plating tank for electrolytic electroplating of molten salt. Molten salt electrolysis of aluminum-containing metal, characterized in that iron ions are reduced by adding aluminum powder having a higher ionization tendency than iron to precipitate as metallic iron, and the metallic iron is subjected to solid-liquid separation from the bath solution. It is a plating method.

That is, the present invention, by immersing the steel material in the molten salt bath liquid of the anode dissolution tank, suspending the cathode plate so as to face it, and energizing so that the steel material becomes the anode, the iron metal on the steel material surface is dissolved. Then, in order to immediately convert the iron ions generated when the surface of the steel material is activated in a reduced state into metallic iron powder, a metal powder having a higher ionization tendency than iron is added and mixed in the anodic dissolution bath of the steel material, This is to prevent iron ions from being contained in the bath liquid adhered to the steel material so that the drawbacks of the previously proposed method can be solved.

〔Example〕

An embodiment in which the present invention is applied to a continuous molten salt electrolytic plating method for steel strips will be described with reference to FIG.

In FIG. 1, 1 is a steel strip, 2 is a plating tank, 2a is an anode melting tank, 3 is a plating tank anode plate, 3a is an anode melting tank cathode plate,
Reference numeral 4 is a plating bath solution, 4a is an anodic dissolution bath solution, 5 and 5a are conductor rolls, 6 and 6a are deflector rolls, and 7 and 7a are direct current power sources (the above 5 to 7, 5a to 7a without the a sign) Is the plating tank 2 and the symbol with a is the anode melting tank 2a
In the figure, 8 is a circulation circuit for the anode dissolution bath liquid 4a, 9 is a pump,
10 is a metal iron machine such as a filter, 11 is a separated metal iron discharge line, and 12 is a metal powder addition line such as aluminum powder having a greater ionization tendency than iron.

As shown in FIG. 1, the steel strip 1 is subjected to degreasing, pickling, rinsing and drying treatments by a device (not shown) and then immersed in the anodic dissolution bath liquid 4a in the anodic dissolution tank 2a by the conductor roll 5a and the deflector roll 6a. Then, the conductor roll 5 and the deflector roll 6 immerse it in the plating bath solution 4 in the plating tank 2, descend and rise, and wind it up on a take-up reel (not shown). In the anode melting tank 2a and the plating tank 2, facing the steel strip 1, the cathode plate 3a,
The anode plate 3 is suspended, and the positive side of the DC power supply 7a is the conductor roll 5a, the negative side is the cathode plate 3a, the positive side of the DC power supply 7 is the anode plate 3, and the negative side is the conductor roll 5. They are connected, and an electric circuit is formed via the bath liquids 4a and 4 respectively.

If the steel strip 1 is continuously supplied to the tanks 2a, 2 and each electric circuit is energized as described above, first, the steel strip 1 is placed in the anodic melting tank 2a.
Is anodically dissolved, the oxide film on the surface is removed and activated, and then subjected to plating treatment in the plating tank 2. At that time, if metal powder such as aluminum powder having a greater ionization tendency than iron is previously dispersed in the anodic dissolution bath liquid 4a through the addition line 12, even if the steel strip 1 is anodically melted and iron ions are generated, It is reduced to metallic iron, and almost no iron ions are present in the bath liquid 4a.

In this way, since the iron powder gradually increases in the anodic dissolution bath solution 4a, the bath solution 4a is sent to the metallic iron separation device 10 by the pump 9 through the circulation circuit 8 and the metallic iron is discharged from the line 11. It

〔The invention's effect〕

According to the present invention, the iron ions generated in the bath solution of the anodic dissolution tank are reduced by the metal having a higher ionization tendency than iron and converted into iron powder, so that the iron ions adhere to the steel material and enter the plating tank. Therefore, the plating process is not impaired, stable operation can be performed for a long time, and a steel material having a plated film with good adhesion can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an embodiment in which the present invention is applied to a continuous molten salt electrolytic plating method for steel strips.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI Technical indication location C25F 7/02 (72) Inventor Toshio Taguchi 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industry Co., Ltd. Hiroshima Institute (72) Inventor Kenichi Yanagi 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd. Hiroshima Works (72) Inventor Junkichi Yoneda 4-6 Kannon Shinmachi, Nishi-ku, Hiroshima Prefecture No.22 Mitsubishi Heavy Industries, Ltd. Hiroshima Works (72) Inventor Junichi Uchida 1-3, Nishi-Nagasumotodori, Amagasaki City, Hyogo Prefecture Sumitomo Metal Industries, Ltd. Research Institute (72) Inventor Hirohisa Seto Amagasaki City, Hyogo Prefecture Nishi-Nagasu Hon-dori 1-3 chome Sumitomo Metal Industries, Ltd. (56) References JP 63-143822 (JP, A) JP-B 41-4566 (JP, B1) JP-B 48-32072 (JP, B1) JP-B 6-86677 (JP, B2) Japan Plating Technology Study Group “Practical plating for field engineers (▲ I ▼) First edition September 25, 1978, published by Maki Shoten, pages 47-49

Claims (1)

[Claims] 1. A method for anodic dissolution of a steel material in a molten salt bath solution of an anodic dissolution tank, activating the surface of the steel material, and then transferring the steel material to a plating tank for electrolytic electroplating of molten salt. A molten salt of an aluminum-containing metal, characterized in that the produced iron ions are reduced by adding aluminum powder having a higher ionization tendency than iron to precipitate as metallic iron, and the metallic iron is subjected to solid-liquid separation from the bath solution. Electrolytic plating method.