KR20110011001A

KR20110011001A - Insoluble anode and method of preparing insoluble anode

Info

Publication number: KR20110011001A
Application number: KR1020090068413A
Authority: KR
Inventors: 류종호; 황덕영
Original assignee: 일진머티리얼즈 주식회사
Priority date: 2009-07-27
Filing date: 2009-07-27
Publication date: 2011-02-08
Also published as: WO2011013911A2; WO2011013911A3

Abstract

The present invention is a positive electrode substrate made of a metal capable of anodization;

A porous oxide layer of the anodized metal integrally formed on the anode substrate; And

An insoluble anode including; an electrode active material layer formed on the oxide layer.

Insoluble anode

Description

Insoluble anode and method for preparing the same

The present invention relates to an insoluble anode, and a method of manufacturing the same, and more particularly, to an insoluble anode including a porous oxide layer of a new structure and a method of manufacturing the same.

An insoluble anode which does not participate in the plating reaction is used in an electrolytic process such as electroplating.

Conventionally, lead or lead alloy has been used as an insoluble anode, but contamination of the plating liquid by the eluted lead, deterioration of film quality, etc. are caused.

A valve metal anode such as titanium does not have a problem such as environmental pollution due to lead. However, in an insoluble anode in which an electrode active material is simply coated on a surface of a valve metal such as titanium, electrolyte penetrates into a crack existing in the electrode active material layer, and an insulating film is formed at the electrode active material layer / valve metal interface. The function of the insoluble anode may be degraded. For example, the electrode active material layer may be peeled from the valve metal by cracks or may be electrically separated even if not peeled off. As a result, the lifetime of the inert anode is shortened.

In order to improve the life of the inert anode, a method of interposing an intermediate layer made of a valve metal other than titanium such as tantalum between the cathode substrate and the electrode active material layer is considered. For example, Japanese Patent Laid-Open No. 1995-1920. However, in the above method, since the intermediate layer is formed by sputtering or the like, it is difficult to prevent the electrolyte from penetrating into the anode substrate / intermediate layer interface, and the corrosion resistance and adhesion are low.

Therefore, there is a need for a technology for producing an inert anode having no problem of environmental pollution, easy to manufacture, excellent in corrosion resistance, abrasion resistance, hardness, and adhesion with a valve metal, and which has an improved lifetime.

One aspect of the present invention is to provide a new insoluble anode.

Another aspect of the present invention is to provide a method for producing the insoluble anode.

According to one aspect of the invention,

A positive electrode substrate made of a metal capable of anodizing;

An insoluble anode is provided, including; an electrode active material layer formed on the oxide layer.

According to another aspect of the invention,

Plasma electrolytic oxidation of the anodized metal to form a porous oxide layer; And

Forming an electrode active material layer on the porous oxide layer; provides an insoluble cathode manufacturing method comprising a.

Insoluble anode according to an aspect of the present invention is excellent in corrosion resistance wear resistance, hardness and adhesion to the valve metal of the insoluble anode by the porous oxide of the valve metal formed integrally with the valve metal, life can be improved.

Hereinafter, an insoluble anode and a method of manufacturing an insoluble anode according to an exemplary embodiment will be described in more detail.

Insoluble anode according to one embodiment is a positive electrode substrate made of a metal capable of anodizing; A porous oxide layer of the anodized metal integrally formed on the anode substrate; And an electroactive material layer formed on the oxide layer. The anodized metal may be a valve metal.

The oxide layer of the valve metal may be formed on the valve metal by plasma electrolytic oxidation. Plasma electrooxidation is a method of forming an oxide layer on a surface by applying a high voltage of 100 V or higher, for example, 200 to 500 V, to an electrode in an electrolyte. When a high voltage is applied to the electrode, a plasma, otherwise an arc or spark, is formed by a strong current field in which gas generated inside the oxide film formed on the electrode surface, for example, oxygen or hydrogen, is locally formed. The oxide layer is formed by the high energy of the plasma. The valve metal may be oxidized by the plasma electrolytic oxidation to form a porous oxide layer. That is, the valve metal may be converted into an oxide layer by the oxidation of the valve metal into the metal by the plasma electrolytic oxidation. Accordingly, the anode substrate made of the valve metal and the oxide layer of the valve metal may be integrally formed. Since the oxide layer formed by a conventional method of powder sintering, spraying or the like does not form an integral part with the valve metal, the adhesion with the valve metal is relatively low.

The metal that can be anodized in the insoluble anode, for example, the valve metal may be selected from the group consisting of titanium, tantalum, zirconium, niobium, and alloys thereof, but is not limited thereto and may be used in the art. Any metal that can be oxidized by plasma electrolytic oxidation can be used.

The porous oxide formed on the titanium substrate, which is one of the valve metals by the plasma electrolytic oxidation in the insoluble anode, may be titanium dioxide, and specifically, the titanium dioxide may be rutile titanium dioxide and anatase titanium dioxide. It may include at the same time. The rutile phase titanium dioxide is a stable phase at a high temperature is generated on the surface of the titanium substrate by the arc generation of high temperature and high pressure during the plasma electrolytic oxidation process, and then quenched by contact with the electrolyte to maintain the original properties. The anatase phase (titanium dioxide) is a phase that can be formed in an initial process before arcing in the plasma electrolytic oxidation process and is a room temperature stable phase that can be easily formed on a general titanium surface. Therefore, the plasma electrolytic oxidation process can improve the corrosion resistance of the porous oxide layer and the adhesion with the titanium substrate by forming a rutile titanium dioxide phase and an anatase titanium dioxide phase that are difficult to form at room temperature on the surface of the titanium substrate.

The thickness of the porous oxide layer formed on the valve metal in the insoluble anode may be 0.1 to 10㎛. For example, it may be 2 to 5㎛. If the thickness of the porous oxide layer formed on the valve metal is too thick, the electrical conductivity of the insoluble anode may be lowered, the adhesion between the porous oxide layer and the valve metal may be lowered, and the manufacturing cost according to the intermediate layer is reduced. If the thickness is too thin, the adhesion to the valve metal and the corrosion resistance may be reduced.

The pore size of the porous oxide layer in the insoluble anode may be 0.1 to 5㎛. For example, it may be 0.2 to 1㎛. If the pore size is too small, the amount of the electrode active material that can penetrate into the pore may be limited. If the pore size is too large, the mechanical strength of the electrode active material layer may be reduced. When the pores are non-spherical, the pore size corresponds to the length of the long axis of the pore.

The porosity of the porous oxide layer in the insoluble anode may be 5 to 30%. For example, it may be 7 to 18%. When the porosity is too low, the amount of the electrode active material that can penetrate into the oxide layer is reduced, the performance of the insoluble anode may be reduced when the electrode active material layer is peeled off. If the porosity is too high, the mechanical strength of the electrode active material layer may be lowered.

In the insoluble anode, the electroactive material may include an oxide of platinum or a platinum group metal, and specifically, may be formed of a mixture of an oxide of a platinum or platinum group metal and an oxide of a valve metal.

For example, iridium-tantalum mixed oxides, iridium-titanium mixed oxides, iridium-ruthenium mixed oxides, iridium-ruthenium-tantalum mixed oxides, ruthenium-titanium mixed oxides, ruthenium-tantalum mixed oxides, iridium-platinum-tantalum Nium mixed oxides; In particular, it may be an iridium-tantalum mixed oxide. The mixing ratio of iridium and tantalum may be, for example, 60-95 wt% of metal iridium and 40-5 wt% of tantalum, or 70-90 wt% of iridium and 30-10 wt% of tantalum.

The amount of the electrode active material layer may be represented by a coating amount (platinum group metal equivalent) per unit area of the electrode active material, and may be 1 to 500 g / m ² . For example, it may be 30 to 300 g / m ² . For example, it may be 50 to 200 g / m ² .

The insoluble anode is excellent in physical properties such as corrosion resistance, adhesion of the porous oxide layer can be improved life.

According to another embodiment, an insoluble anode manufacturing method includes plasma electrolytic oxidation of an anodized metal to form a porous oxide layer; And forming an electrode active material layer on the porous oxide layer. The anodized metal may be a valve metal.

Forming the porous oxide layer is made by plasma electrolytic oxidation. The electrolyte in which the plasma electrolytic oxidation is performed may be a general alkaline electrolyte. PH of the electrolyte solution may be 8 to 13. The voltage applied to the electrode in the plasma electrolytic oxidation may be 100V or more. For example, it may be 200 to 500V. Power applied to the electrode in the plasma electrolytic oxidation may be 0.01 to 1000KW. For example, it may be 1 to 100 KW. In the plasma electrolytic oxidation, the current density applied to the electrode may be 0.001 to 100 A / dm ² . For example, it may be 1 to 50 A / dm ² . The time for flowing the current may be 1 to 100 minutes, for example, 1 to 10 minutes. In the plasma electrolytic oxidation, a valve metal specimen may be used as the anode and stainless steel may be used as the counter electrode. However, the present invention is not limited to stainless steel, and any type of counter metal may be used as the counter electrode in the art.

For example, the porous oxide layer may be formed by using a titanium valve metal specimen as an anode and using stainless steel as a counter electrode in an alkaline aqueous solution having a pH of 12.9 in which potassium pyrophosphate is dissolved 0.02M. This can be done by flowing an alternating current for 2 minutes at a current density of 10 A / dm ² .

As described above, the plasma electrolytic oxidation is environmentally friendly because it uses an alkaline electrolytic solution that does not contain environmental contaminants such as chromium and manganese in the electrolytic solution. In addition, the porous oxide layer is produced at a high speed, and can be performed even without a pretreatment step, thereby increasing productivity. In addition, since the porous oxide layer is formed integrally with the positive electrode substrate, high corrosion resistance, abrasion resistance, hardness, and adhesion can be obtained with only a thin porous oxide layer thickness. In addition, there is no need for vacuum equipment as in vapor deposition, and there is no restriction in size and shape of the product to be applied. The plasma electrolytic oxidation can be processed in a batch when a fast process speed is used and a roll type positive electrode substrate is used.

The forming of the electrode active material layer may be performed using vapor deposition methods including pyrolysis, electrochemical oxidation, powder sintering, and sputtering. In particular, pyrolysis can be used. For example, the forming of the electrode active material layer may be performed by dissolving one or more precursors of the metal oxide in a solution, applying the solution onto the porous oxide layer, and drying the solution. It may be carried out by a process for heat treatment in. The process may be repeated several times to several tens as necessary to obtain an electrode active material layer.

The precursor of the at least one metal oxide may be a precursor of an oxide of a platinum or platinum group metal, and specifically, may be a mixture of an oxide precursor of a platinum or platinum group metal and an oxide precursor of a valve metal.

For example, the precursor of the iridium-tantalum mixed oxide, the precursor of the iridium-titanium mixed oxide, the precursor of the iridium-ruthenium mixed oxide, the precursor of the iridium-ruthenium-tantalum mixed oxide, the precursor of the ruthenium-titanium mixed oxide, the ruthenium-tantalum Precursors of mixed oxides, precursors of iridium-platinum-tantalum mixed oxides, and the like. In particular, it may be a precursor of the iridium-tantalum mixed oxide.

As a result, the insoluble anode manufacturing method is simple in the manufacturing process, does not use expensive equipment or raw materials, and can be a continuous process is low in manufacturing cost and advantageous for mass production. Moreover, the physical properties, such as corrosion resistance and adhesiveness of a porous oxide layer, are also excellent. Therefore, an insoluble anode having an improved lifetime can be manufactured with high economical efficiency and productivity.

In the method of manufacturing an insoluble anode, it may further include a pretreatment step of roughening the surface of the valve metal before the step of forming the porous oxide layer.

The pretreatment may be performed by, for example, blasting, chemical etching or the like. The surface of the positive electrode substrate may be roughened by the pretreatment. The roughened anode substrate may make it easier to form the porous oxide layer of the valve metal.

In the insoluble cathode manufacturing method, the porous oxide may be titanium dioxide (TiO ₂ ). Specifically, the porous oxide may simultaneously include rutile titanium dioxide and anatase titanium dioxide. Details thereof are as described above in the insoluble electrode portion.

Hereinafter, the present invention will be described in more detail with reference to preferred examples, but the present invention is not limited thereto.

(Manufacture of Insoluble Anode)

Example 1

A commercially pure titanium substrate of 15 mm (width) x 20 mm (length) x 2 mm (thickness) was prepared. The titanium substrate was uniformly polished with SiC paper # 1000, washed with alcohol and dried at room temperature.

In a basic electrolyte solution (pH 12.9) in which potassium pyrophosphate 0.02M is dissolved, the pretreated titanium substrate is used as a cathode and a stainless steel as a cathode, and plasma electrooxidation is performed for 2 minutes at a current density of 10 A / dm ² using an output of 20 KW. Was carried out to form a porous titanium dioxide layer on the titanium substrate. The electrolyte was stirred during the plasma electrolytic oxidation and the temperature of the electrolyte was maintained at 30 ° C.

An electrode coating liquid (TaCl ₅ 0.32g, H ₂ IrCl ₆ · 6H ₂ O 1.00g, 35% HCl 1.0ml, n-butanol 10.0ml) was applied to the titanium substrate on which the titanium dioxide layer was formed, and dried for 10 minutes. It was calcined and oxidized in air at 450 ° C. for 30 minutes.

The above process was repeated 10 times to form a 5 μm iridium-tantalum mixed oxide electrode active material layer to prepare an insoluble electrode.

Example 2

An insoluble electrode was manufactured in the same manner as in Example 1, except that a pretreatment step such as polishing by SiC paper was omitted.

Example 3

The commercially pure titanium substrate (15 mm (width) x 20 mm (length) x 2 mm (thickness)) was uniformly polished with SiC paper # 1000, washed with alcohol and dried at room temperature.

In the basic electrolyte solution (pH 12.9) in which potassium pyrophosphate 0.02M was dissolved, the pretreated titanium substrate was used as a cathode and a stainless steel as a cathode, and plasma electrooxidation was performed for 5 minutes at a current density of 10 A / dm ² using an output of 20 KW. Was performed to form a porous titanium dioxide layer on the titanium substrate. The electrolyte was stirred during the plasma electrolytic oxidation and the temperature of the electrolyte was maintained at 30 ° C.

Example 4

The commercially pure titanium substrate (15 mm (width) x 20 mm (length) x 2 mm (thickness)) was uniformly polished with SiC paper # 1000, washed with alcohol and dried at room temperature. In the basic electrolyte solution (pH 12.9) in which potassium pyrophosphate 0.05M was dissolved, the pretreated titanium substrate was used as a cathode and a stainless steel as a cathode, and plasma electrooxidation was performed for 10 minutes at a current density of 10 A / dm ² using an output of 20 KW. Was carried out to form a porous titanium dioxide layer on the titanium substrate. The electrolyte was stirred during the plasma electrolytic oxidation and the temperature of the electrolyte was maintained at 30 ° C.

An electrode coating liquid (TaCl ₅ 0.32g, H ₂ IrCl ₆ .6H ₂ O 1.00g, 35% HCl 1.0ml, n-butanol 10.0ml) was applied to the titanium substrate on which the titanium dioxide layer was formed, and dried for 10 minutes. It was calcined and oxidized in air at 450 ° C. for 30 minutes.

Evaluation Example 1 Evaluation of Structure of Porous Oxide Layer

Scanning electron microscopy and X-ray diffraction experiments were performed on the titanium dioxide oxide layer formed in the porous oxide layer forming step of Example 1. The results are shown in FIGS.

The titanium dioxide oxide layer as shown in FIG. 1 was porous and the pore size ranged from 0.2 to 2 μm. As shown in FIG. 2, pores were present in the titanium dioxide oxide layer. In addition, the thickness of the oxide layer was in the range of 1.5 to 2.5㎛. Since the titanium dioxide is formed from a titanium substrate by plasma electrolytic oxidation, the titanium dioxide is integrally formed with the titanium substrate.

As shown in FIG. 3, the rutile phase and the anatase phase were present in the porous titanium dioxide layer as a result of the X-ray diffraction experiment.

1 is a scanning electron microscope (Scanning Electron Microscopy) photograph of the surface of the porous coating layer formed in Example 1.

Figure 2 is a scanning electron micrograph of the cross section of the porous coating layer formed in Example 1.

3 is an X-ray diffraction test result of the porous coating layer formed in Example 1.

Claims

A positive electrode substrate made of a metal capable of anodizing;

And an electroactive material layer formed on the oxide layer.

The insoluble anode according to claim 1, wherein the metal capable of anodizing is a valve metal.

The insoluble anode according to claim 1, wherein the metal capable of anodizing is selected from the group consisting of titanium, tantalum, zirconium, niobium, tungsten, and alloys thereof.

The insoluble anode according to claim 1, wherein the porous oxide is titanium dioxide.

The insoluble anode according to claim 1, wherein the porous oxide simultaneously contains rutile titanium dioxide and anatase titanium dioxide.

The insoluble anode according to claim 1, wherein the electroactive material comprises an oxide of platinum or a platinum group metal.

The insoluble anode according to claim 1, wherein the electroactive material is composed of an oxide of platinum or a platinum group metal and an oxide of a valve metal.

Forming an electrode active material layer on the porous oxide layer; Insoluble anode manufacturing method comprising a.

The insoluble anode according to claim 8, wherein the metal capable of anodizing is a valve metal.

9. The method of claim 8, further comprising a pretreatment step of roughening the surface of the anodized metal before forming the porous oxide layer.

The method of claim 8, wherein the porous oxide is titanium dioxide.

The method of claim 8, wherein the porous oxide comprises rutile titanium dioxide and anatase titanium dioxide at the same time.