JPH0762583A - Electrolytic electrode - Google Patents

Abstract

PURPOSE:To obtain an electrolytic electrode capable of conducting stabilized electrolysis over a long period at the time of detachably fixing an electrode unit consisting of insoluble metal on a current feeder by attaching a conductive member of corrosion-resistant metal on the contact surface between the unit and feeder at a fixed part. CONSTITUTION:A boss 2 for bolting is integrally fixed to an electrode unit 1 consisting of insoluble metal, a gasket 4 and a ribbon conductive member 5 are inserted between a titanium-clad current feeder 3 and the boss 2 and bolted by a bolt 6. Consequently, an electrolyte, etc., do not intrude between the boss 2 and the feeder 3 and into the joining part of the bolt 6 and feeder 3, thereby an electrode capable of being operated for a long period is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode for electrolysis, and more particularly to an insoluble electrode to an electrode for electrolysis used in an electrolytic production apparatus for metal foil such as copper foil and a plating apparatus for steel sheet.

[0002]

2. Description of the Related Art In continuous high-speed electroplating equipment represented by zinc plating and tin plating of steel sheets, insoluble lead and lead alloy electrodes have been used. In these devices, the effective electrode area of the electrodes was as large as 1 to ³ m ² per electrode.

In a metal foil continuous electrolytic production apparatus represented by electrolytic production of copper foil, a lead alloy electrode has been used for a long time as an anode facing a cylindrical cathode. The size is 1-3m in diameter, 1-2m in width, 0.7-5.0m.
^It encloses a quarter of a cylindrical cathode having a size of ^{2 and has} a size of 3.5 to 4 m ² . The lead alloy electrode has a low melting point and is easy to process, and even if it is large, it is easy to weld and match the shape at the installation site of the metal foil manufacturing device, and the problem of processing is relatively Not a few.

However, it is difficult to form a uniform electrochemically uniform electrode surface on the entire surface of a large electrode, and even an electrode used for the purpose of energization as a counter electrode of a cathode, which is a working electrode, is uniformly applied to electricity. Although it is easy to use as an electrode for an electroplating apparatus or a metal foil manufacturing apparatus that requires high performance, it has a major drawback in achieving high accuracy.

Further, these insoluble electrodes have a very large consumption at the time of electrolysis of several mg to several tens of mg / Ah, and the shape of the electrode surface changes greatly. Therefore, it is necessary to frequently perform maintenance for the correction. With the problem
Of the consumed electrode components, lead pollutes the electrolytic solution as metallic lead, lead ions, or lead sulfate or lead oxide, and mixes with the product to cause product quality deterioration, wastewater treatment problems, and environmental pollution. There was a problem. Therefore, in order to solve these problems, an insoluble metal electrode in which a thin film-forming metal surface such as titanium is coated with a conductive electrode substance containing a platinum group metal or an oxide thereof has been used in recent years. In particular, an insoluble electrode formed with a coating containing an oxide of a platinum group metal has characteristics of long life and low potential.

Since it is difficult to manufacture a large insoluble electrode on which a coating containing a noble metal oxide is formed, a large-sized electrolysis electrode is a large number of insoluble metal single electrodes which are easy to handle on an electrode substrate having a small conductive resistance. It is manufactured by combining The insoluble electrode alone is attached to the electrode substrate by welding or bolting, but the insoluble metal electrode can be obtained by using the metal obtained even if a small part of the electrode coating deteriorates during use. Since the foil and plated products are non-uniform, it is necessary to regenerate the entire surface rather than treating the electrode coating partially. Therefore, the insoluble metal electrode alone is attached by using a detachable fixing means such as bolting, which makes it easy to replace only the insoluble metal electrode alone whose electrode coating is deteriorated.

A thin film-forming metal such as titanium is used as an electrode substrate in the electrolytic production of metal foils and the production of electrodes used for electroplating, but it has an oxide layer on the surface. When it is attached by a fixing means such as a bolt, the contact resistance is large, and when it is operated for a long time, the contact resistance is increased due to corrosion, and the joint portion is eluted. In addition, a power supply body that supplies a current to the electrode is also detachably formed between the electrode and the electrode by a fixing means that is detachable when attaching and detaching the electrode to and from the electrolytic cell. Also at the joint, there have been problems such as an increase in contact resistance due to corrosion and elution of the joint.

[0008]

SUMMARY OF THE INVENTION According to the present invention, the contact resistance between the connecting portion between the electrode unit and the electrode base body which can be removed at the connecting portion or between the electrode base body and the current supply body is reduced, and the connection is made. It is an object of the present invention to provide an electrode for electrolysis in which corrosion is prevented from occurring in a part.

[0009]

The electrode for electrolysis of the present invention comprises:
In an electrolysis electrode having a detachably attachable portion, a corrosion-resistant conductive coating is formed on both contact surfaces of the attachable portion,
Alternatively, it is an electrode for electrolysis in which a conductive member made of a corrosion-resistant metal or a metal having a corrosion-resistant conductive coating is provided and fixed. In addition, the fixing portion is an electrode for electrolysis which is at least one of a fixing portion between the single electrode and the electrode base or a fixing portion between the electrode base and the current supply means. Also,
The electrode for electrolysis, in which the corrosion-resistant conductive coating contains a platinum group metal, a platinum group metal oxide, and a thin film forming metal oxide.

That is, in the electrode for electrolysis of the present invention, when an electrode unit made of a thin plate-shaped insoluble metal electrode made of expanded metal or the like is fixed on the electrode base by a detachable fixing means, Iridium, platinum,
Films of platinum group metals with high corrosion resistance such as ruthenium, palladium and rhodium, platinum group metal oxides, oxides of thin film forming metals such as titanium, tantalum, niobium and zirconium, or platinum group metals and thin film forming metals It is a composite of oxides of the above.

Further, the electrode for electrolysis of the present invention has, on the contact surface, a film of a platinum group metal having high corrosion resistance such as iridium, platinum, ruthenium, palladium and rhodium, a platinum group metal oxide, titanium, tantalum, niobium and zirconium. A metal coated with an oxide of a thin film-forming metal such as the above, or a complex of a platinum group metal and an oxide of a thin film forming metal is provided and fixed. Various metals can be used as the metal forming the corrosion-resistant conductive coating, but it is preferable to use a thin film-forming metal having high corrosion resistance and conductivity. When the conductive coating is a platinum group metal,
The thickness is preferably 0.05 μm or more, and 0.05 μm
It is preferable that the thickness be in the above range, and if it is 0.05 μm or less, the contact surface cannot be sufficiently covered. When the conductive coating is an oxide, the thickness is preferably 0.1 μm or more, and
When the thickness is 1 μm or less, the contact surface is not sufficiently covered and peeling easily occurs, which is not preferable.

The corrosion resistant conductive coating can be formed by electroplating or chemical plating in the case of a metal such as platinum. Further, in the case of a metal oxide, it can be formed by applying a solution of a compound of the corresponding metal and heating and firing in an oxygen-containing atmosphere. The metal used for the corrosion-resistant conductive coating is preferably a platinum group metal, particularly platinum, and the metal member to be interposed in the joint is silver, lead, tin, aluminum, titanium, vanadium, zirconium, niobium, tantalum, or the like. And titanium is particularly preferable. Further, in order to form a conductive coating of a metal oxide so that the electrode substrate is large and does not give a thermal strain to the electrode substrate, a method of applying an oxide gel and then drying it, or applying a metal compound is applied. After that, it can be carried out by a method of locally heat treating with a burner or the like.

The present invention will be described below with reference to the drawings.
FIG. 1 is a view showing a cross section of a coupling portion for explaining one embodiment of an electrolysis electrode of the present invention. A boss 2 for bolt connection is integrally attached to the electrode single body 1, and a gasket 4 is provided between the current supply body 3 clad with titanium and the boss.
And a ring-shaped conductive member 5 is provided and coupled by bolts 6. Between the boss and the current supply, between the bolt and the current supply, and between the boss and the current supply,
The gasket 4 has a structure in which the electrolytic solution or the like does not enter the joint portion. Further, FIG. 2 is a view showing a cross section of a coupling portion for explaining another embodiment. A stud bolt 8 is attached to the connecting rib 7 of the single electrode 1, and a gasket 4 and a conductive member 5 are provided between the electrode 7 and the current supply body 3.
Is provided and attached by the cap nut 9. The cap nut 9 and the current supply body 3 are coupled by an O-ring 10, and the cap nut is provided with a gasket 4 between the cap nut and the current supply body to cover the coupling portion with an electrolyte solution or the like. Prevents intrusion. Further, FIG. 3 is a view showing a cross section of a joint portion in which a conductive coating is formed on the connection surface.

A conductive coating 13 is formed on the substrates 12 to be bonded, and further fixed by screws 15 via a contact plate 14 having an electrocatalyst coating, so that the conductive connection at the contact surface is stable for a long time. Hold on.

[0015]

The electrode for electrolysis according to the present invention has a corrosion-resistant surface on both sides of the detachable fixing portion between the single electrode and the electrode base body or the detachable fixing portion between the electrode base body and the current supply body. By forming a certain conductive coating or by interposing a conductive member made of metal with a corrosion-resistant conductive coating formed on the contact portion, the contact resistance at the fixed portion can be reduced, and the fixed portion can be kept for a long time. It can be kept in good condition.

[0016]

EXAMPLES The present invention will be described in more detail below by showing Examples of the present invention. Example 1 An electrode having an electrode coating of IrO ₂ : 70 wt% and Ta ₂ O ₅ : 30 wt% formed on a titanium substrate having a length of 100 mm, a width of 100 mm and a thickness of 3 mm has an outer diameter of 28 mm and an inner diameter of 17 mm.
Welded titanium bosses of 100 mm in length and 500 m in width
A titanium current supply body having a thickness of 10 mm and a thickness of 10 mm was fastened with a bolt so that the axial force of the bolt was 1000 kgf and was fastened. The joint surfaces of the boss and the electrode substrate were surface-coated with the materials shown in the table below. The surface roughness of each joint surface was 10 μm or less in Rmax, the following conductive member was interposed in the joint portion, and the contact resistance was expressed by the potential difference generated at the joint portion when a current of 20 A was applied. In Table 1, the ratio indicates that it is a comparative example. Sample No. 1 is electroplated with platinum having a thickness of 0.5 μm, and Sample No. 2 is electroconductive obtained by electroplating platinum with a thickness of 3 μm on the surface of titanium having an outer diameter of 28 mm, an inner diameter of 18 mm and a thickness of 1 mm. I am using a member. In addition, sample No. 3 has an outer diameter of 28 m
m, an inner diameter of 18 mm and a thickness of 10 μm were used as the conductive member. In Sample No. 3, when the platinum foil is used as the conductive member, the platinum foil has a mirror-like surface, and thus it is considered that the contact portion on the joint surface is small and the contact resistance is large.

[0017]

[Table 1]

Example 2 The electrode produced in the same manner as in Example 1 was subjected to long-term electrolysis in 3N sulfuric acid at 60 ° C. as an anode at a current density of 100 A / dm ² . Table 2 shows the voltage rise value of each junction after 200 hours. Sample No. 5 is platinum having a thickness of 0.3 μm formed by electroplating, and Sample No. 6 is IrO ₂ : 70 wt%, Ta.
₂ O ₅ : A coating having a composition of 30 wt% and a thickness of 5 μm was formed by thermal decomposition. Sample No. 7 was Ti.
A coating having a composition of O ₂ : 50 wt% and Ta ₂ O ₅ : 50 wt% and a thickness of 0.5 μm is formed by thermal decomposition.

[0019]

[Table 2]

[0020]

EFFECT OF THE INVENTION The electrolysis electrode of the present invention makes contact on both the contact surfaces of the detachable fixing portion between the single electrode body made of insoluble metal or the like and the electrode base body or the detachable fixing portion between the electrode base body and the current supply body. It is possible to obtain an electrode for electrolysis that reduces the resistance value and enables stable electrolysis for a long period of time.

[Brief description of drawings]

FIG. 1 is a view showing a cross section of a coupling portion for explaining an embodiment of an electrode for electrolysis of the present invention.

FIG. 2 is a view showing a cross section of a coupling portion for explaining another embodiment of the present invention.

FIG. 3 is a view showing a cross section of a joint portion in which a conductive film is formed on a connection surface.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Single electrode, 2 ... Boss, 3 ... Current supply body, 4 ... Gasket, 5 ... Conductive member, 6 ... Bolt, 7 ... Connection rib, 8
… Stud bolts, 9… Cap nuts, 10… O-rings, 1
1 ... Cap, 12 ... Base, 13 ... Conductive coating, 14 ...
Touch plate, 15 ... Screw

Claims (3)

[Claims] 1. In an electrode for electrolysis having a detachable fixing portion, a corrosion-resistant conductive coating is formed on both contact surfaces of the fixing portion, or a corrosion-resistant metal or a corrosion-resistant conductive coating is formed on both contact surfaces. An electrode for electrolysis, characterized in that a conductive member made of metal on which is formed is provided and fixed. 2. The fixing portion is at least one of a fixing portion between an electrode single body and an electrode base body or a fixing portion between an electrode base body and a current supply means.
The electrode for electrolysis described. 3. The corrosion resistant conductive coating is a platinum group metal,
The electrode for electrolysis according to claim 1 or 2, which contains a metal oxide of a platinum group and an oxide of a thin film-forming metal.