JPS6028913B2 - Manufacturing method of electrolytic iron foil - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing ductile electrolytic iron foil.

Electrolytic iron foil is obtained by electrodepositing iron to a predetermined thickness on a peelable lightning rust substrate such as stainless steel, titanium, niobium, etc., and then peeling it off.

Its manufacturing methods include a soluble anode method that uses iron or steel as the raw material for the anode, and a non-meltable anode method that uses a non-lacquered anode such as carbon and melts the iron or steel as the raw material in a separate tank. There is sexual anodization. In the former case, as the anode wears out, the distance between the anode and cathode changes, and eventually it is necessary to replace the anode. In addition, in order to maintain a constant distance between the poles, it is necessary to process it into a shape that corresponds to the exposure mirror substrate, and it is difficult to use inexpensive iron scraps as a raw material for electrolytic iron foil. Furthermore, powdered iron generated during melting of the anode tends to get caught up in the electrodeposit, making it impossible to obtain an electrolytic iron foil with a good surface condition. In the latter non-fusible anodic method, instead of dissolving iron at the anode, an oxidation reaction of ferrous ions (Fe12→Fe13) occurs to produce ferric ions. Ferric ions are taken out of the electrolytic tank and reduced to ferrous ions with iron and copper in a separate regeneration tank.
It partially hydrolyzes, turns into sludge, and gets caught in lightning kimono, causing embrittlement of electrolytic iron foil. In particular, when a high current density is used to increase productivity, verticalization due to ferric ions is significant, and the iron electrodeposit may not be able to be peeled off from the lightning coin base. For this reason, methods have been devised to prevent ferric ions from migrating to the cathode, such as by using a corneal membrane between the anode and the cathode, or by circulating an electrolytic solution in a laminar flow between the cathode and the anode.
However, when producing electrolytic iron foil continuously, the military base is operated in the form of a drum or an endless belt, so the diaphragm method requires complicated equipment and also creates a laminar flow between the cathode and anode. This is also extremely difficult to implement. The purpose of the present invention is to produce electrolytic iron foil that uses an insoluble anode in a simple electrolytic cell that does not require a diaphragm or laminar flow, and that does not lose its ductility even if ferric ions are mixed into the cathode. The purpose is to produce foils at high current densities.

In view of the above objectives, after various studies, we found that an iron chloride solution containing an unprecedentedly high concentration of ferrous ions was used as the electrolyte, and an excess of chlorine ions than the amount of chlorine ions equivalent to the amount of iron ions in the electrolyte, In other words, it was found that by performing iron electrodeposition while adjusting the amount of free hydrochloric acid, ductile electrolytic iron foil could be obtained at high current density without using complicated methods such as diaphragm method or laminar flow method. .

The concentration of ferrous ions is 200 to 400 g/s, preferably 250 to 300 g/s, and if it is less than 200 g/s, the ductility of the electrolytic iron foil will decrease, and the dew stress will increase, significantly. It becomes impossible to peel off the electroplating substrate.

In addition, when increasing the current density to 50 A/d or more to increase productivity, electrolytic iron foil tends to become sluggish, but if the concentration of ferrous ions is 25 female or more, such high current Electrolytic iron foil with good ductility also in terms of density can be obtained. If the ferrous ion concentration exceeds 400 g/concentration, the electrolytic iron foil will not only increase significantly and consume power unnecessarily, but also cause iron chloride to crystallize easily, which is not preferable. Furthermore, if the amount of free hydrochloric acid is small, even if the amount of ferrous ions is increased, an electrolytic iron foil with good ductility cannot be obtained. The difference between the total amount of chlorine ions in the electrolyte and the amount of chlorine ions combined with iron ions is the amount of free hydrochloric acid, and the amount of free hydrochloric acid is 2 to 60 g.
Noyu is preferred. When the amount of free hydrochloric acid becomes less than 2g',
The influence of ferric ions cannot be suppressed, and the ductility of the electrolytic iron foil decreases. When the amount of free hydrochloric acid exceeds 60 g'〆, the iron adhesion efficiency decreases significantly, and ``due to hydrogen generation, blisters are formed at the interface between the haze coin substrate and the adhering iron, and the surface of the electrolytic iron foil obtained is This is undesirable because it becomes uneven.When the amount of free hydrochloric acid is 2g/at that time, the pH in terms of hydrogen ion concentration is approximately 0.
In order to suppress the influence of ferric ions, the pH needs to be 0 or less. Such a low pH,
In other words, although we have not seen any examples of iron electrodeposition at high hydrogen ion concentrations, by increasing the ferrous ion concentration, iron electrodeposition can be performed with a high electrodeposition efficiency of 80 to 95%. . The ferrous ion concentration of a normal iron electrolyte is less than 15 mm/h, and in such an electrolyte, if the pH is lowered to 0 or less, the electrodeposition stress is high, cracks occur, and the electrolytic iron foil becomes hazy. It cannot be peeled off from the coin base. As a method of adjusting the amount of free hydrochloric acid within the range of 2 to 60 g, the amount of iron and steel, which is a reducing agent for ferric ions and a raw material for electrolytic iron foil, added to the regeneration tank is adjusted to prevent excess There are methods such as suppressing the dissolution of iron or adding hydrochloric acid. Although it is possible to temporarily add other acids such as sulfuric acid or hydrofluoric acid instead of hydrochloric acid, it is not preferred because these acids accumulate and have adverse effects during long-term exposure. As mentioned above, since the electrolytic solution contains free hydrochloric acid and has a high hydrogen ion concentration, the electrolysis temperature is preferably 90q0 or higher, and if it is 900 or higher, the stress of dew is high and the iron that is debonded becomes sulfurized. , cannot be separated from the base for Russian coins, and iron foil cannot be obtained. Moreover, if the temperature exceeds 12,000 degrees, the electrolytic solution will boil and the surface condition of the electrolytic iron foil will deteriorate, which is not preferable, and the appropriate temperature range is 90 to 120 degrees. In the production of electrolytic iron foil using the above-mentioned insoluble anode, a solution containing ferrous ions at a high concentration of 200 to 400 g/ml is used as the electrolyte, and the amount of free hydrochloric acid is adjusted to 2 to 60 g/ml. By applying this method, long electrolytic iron foils can be easily manufactured continuously without separating the electrolyte between the anode and cathode as in the diaphragm or laminar flow method, and the current density can be increased. An electrolytic iron foil having ductility that can withstand use even if Further, examples will be specifically explained.

Using an electrolytic cell with a rotating titanium drum as the cathode and a carbon anode placed one ship's distance from the cathode, the ferrous ion concentration was 100, 150, 200, 250, 300.
, 350, 400 g/The iron chloride solution was used as the electrolyte, the current density was 30, 50, 70 A/d, the temperature was 103 to 105
Iron was deposited on the drum to a thickness of 25 m under conditions of 0.00, and then peeled off from the drum to obtain an electrolytic iron foil.

Since ferric ions are generated at the anode, the electrolytic solution was taken out from the electrolytic cell, and in a separately provided regeneration tank, the ferric ions were reduced to ferrous ions using iron scrap, and then returned to the electrolytic cell. In the regeneration tank, the amount of free hydrochloric acid was adjusted to 5 to 1 by adjusting the amount of iron scrap and adding hydrochloric acid. The obtained electrolytic iron foil was cut into a length of 20 squares and subjected to a 90° bending test, and the ductility of the electrolytic iron foil was evaluated by the number of times it was bent until it broke.
The results are shown by the solid line in FIG. As shown in FIG. 1, if the ferrous ion content was less than 200 g', an electrolytic iron foil with good ductility could not be obtained. In addition, ferrous ion is 25 female/
Even at a high current density of 50 A/d or higher, an electrolytic iron foil with good ductility could be obtained. Comparative Example 1 In an electrolytic cell similar to Example 1, the ferrous ion concentration was 20
0,250,300,350g'The iron chloride solution was used as the electrolyte, and the current density was 30,50,70A/d.
Iron was deposited on the drum to a thickness of 25 mm and peeled off from the drum to obtain an electrolytic iron foil.

Since ferric ions are generated at the anode, the electrolytic solution was taken out from the electrolytic cell, and in a separately provided regeneration tank, the ferric ions were reduced to ferrous ions using iron scrap, and then returned to the electrolytic cell. At this time, the amount of iron scrap was adjusted so that the amount of free hydrochloric acid was 2 g/or less and the pH was 0.3 to 0.8. The ductility of the obtained electrolytic iron foil was evaluated by a bending test, and the results are shown by the broken line in FIG. As shown in FIG. 1, even if the ferrous ion concentration was high, the amount of free hydrochloric acid was small, so an iron foil with good ductility could not be obtained. Example
2 In an electrolytic cell similar to Example 1, ferrous ions were
A solution containing 0 g is used as an electrolyte, and the current density is 30, 50,
70 A/d, temperature 103~1060, thickness 2
Iron was electrodeposited on a 5 mm plate and peeled off from the drum to obtain an electrolytic iron foil.

At this time, in the regeneration tank for reducing ferric ions, the amount of iron scrap and the amount of hydrochloric acid added were adjusted to vary the amount of free hydrochloric acid from 0.5 to 20 g/so. The ductility of the electrolytic iron foil thus obtained was evaluated by a bending test and is shown in FIG. As shown in FIG. 2, when the amount of free hydrochloric acid was 2 g/or more, an iron foil with good ductility was obtained. Comparative Example 2 In an electrolytic cell similar to Example 1, ferrous ions were
A solution containing 5g/〆 was used as an electrolyte, and a current density of 30, 50,
Electrodeposition of iron to a thickness of 25 mm was carried out under conditions of 70 A/d and a temperature of 103 to 10,500 mm.

At this time, in the regeneration tank for reducing ferric ions, the amount of iron scrap and the amount of hydrochloric acid added were adjusted to change the amount of free hydrochloric acid by 1,5,log'. When trying to obtain electrolytic iron foil in this way, the amount of free hydrochloric acid was 5,
log/so, and current density is 50A/d, 70A/
In the case of d, the exposure stress was extremely large and cracks occurred, making it impossible to take out the foil. Further, an electrolytic iron foil was obtained under the conditions that the amount of free hydrochloric acid was 1 g/d and the current density was 3/d, but the number of bending was less than 10, and the ductility of the electrolytic iron foil was not good.

[Brief explanation of drawings]

FIG. 1 shows the relationship between the ductility of electrolytic iron foil and the ferrous ion concentration in the electrolytic solution, and FIG. 2 shows the relationship between the ductility of electrolytic iron foil and the amount of free hydrochloric acid. Kaya' figure 2

Claims (1)

[Claims] 1. In a method for producing electrolytic iron foil by electrodepositing iron on an electroforming substrate using an insoluble anode and peeling off the electrodeposited iron layer,
An iron chloride solution containing 200 to 400 g/l of ferrous ions is used as the electrolyte, and the amount of free hydrochloric acid in the electrolyte is 2 to 60 g/l.
1. A method for producing electrolytic iron foil, which comprises performing iron electrodeposition at a temperature of 90 to 120° C. while adjusting the temperature to 1.