JPS63203800A - Electrode and its production - Google Patents

Abstract

PURPOSE:To permit extension of the life of the titled electrode, reduction of energy consumption and improvement in working efficiency by coating an alcohol soln. of respective chlorides of Ir and Ta on a Ti base material and drying the coating, then heating the same in an oxidizing atmosphere. CONSTITUTION:The electrode suitable for a surface treatment such as electrolytic deposition is produced by coating the alcohol soln. of the respective chlorides of Ir and Ta on the base material consisting of metal Ti, drying the coating at about 120 deg.C, repeating the coating stage and drying stage plural times and calcining the coatings for 20min at 350-400 deg.C in the oxidizing atmosphere. The compounding ratio of the respective chlorides of Ir and Ta is so selected that the weight ratio of Ir and Ta is within a (1:1.5)-(1:4) range. The reduction of energy consumption is permitted with the above-mentioned electrode by this method; for example, the prescribed electrolytic speed is obtd. with the lower applied voltage; in addition, the change to bring the electrode into a passive state is suppressed and longer life as the electrode is obtd. Decomposition of the org. matter contained in the treating liquid is obviated and the operation to clean the treating liquid is decreased. The working efficiency is thus improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electrode suitable for use in surface treatment of various electrochemical reaction devices, etc., and a method for manufacturing the same.

BACKGROUND ART Conventionally, electrolytic deposition of metal thin films for magnetic devices, gold plating for connectors, and circuit formation using electrolyte 1w4 for printed wiring boards have been used, for example, zinc plating (zinc plating) for steel plates constituting automobile bodies, etc. Surface treatment techniques that utilize electrolytic deposition reactions are widely used in the field of surface treatments such as zinc alloy plating or tin plating of steel sheets for 91 cans.

Such surface treatment is carried out by electrolytic treatment, in which the object to be treated is immersed in an electrolytic bath in which an electrode is immersed, and the electrolytic deposition is performed by passing electricity between the electrode and the object to be treated. The material of the electrode used is electrolytic IJ1. It is known to have a significant impact on elephants.

Conventionally, lead oxide (pbo□) electrodes, ferrite electrodes, platinum-plated titanium electrodes, and the like have been used as such electrodes.

Electrodes made of these materials decompose organic chemicals and growth additives in the electrolyte relatively quickly, thereby causing deterioration of the electrolyte, and cleaning such electrolytes requires, for example, abrasion with activated carbon. work needs to be done. Therefore, there was a problem in that the entire production line including this electrolytic process had to be stopped.

Furthermore, in the industrial field of gold plating, bright copper plating, tin plating for can manufacturing, etc., platinum/titanium ml is used as an anode for plating. Various organic chemicals and organic additives are also used in the plating solution for performing such various platings, and there is a problem that these are decomposed at a high speed as in the prior art example described above. Furthermore, in order to obtain a predetermined electrolysis rate, the applied voltage must be set relatively high, resulting in the problem of consuming a large amount of power. Another problem is that the electrode becomes passivated as the plating process progresses, resulting in a relatively short lifespan as an electrode.

Furthermore, in the case of gold plating, for example, the oxidation number of the plating metal (gold) increases, resulting in a problem α in which the tlY cost and electric power amount increases. That is, when gold plating is performed, the oxidation number of gold is increased by the following reaction.

A u”-A u”-(1)
Therefore, in order to deposit gold ions, which have become trivalent cations, on the object to be plated, it is necessary to perform the reduction action shown in the second and third equations below. The power used to operate the computer is wasted.

A u” -A u' -(2
)Au+→Au...(3)
Still another prior art is disclosed in Japanese Patent Application Laid-Open No. 55-38951. This is titanium (T i) and tantalum (T
a), niobium (N b), zinc (Zn), etc. at 0.05
An alloy containing ~10fii1% is used as a base, and a mixed oxide film of tantalum and iridium is formed on this base. In addition, as another conventional technique, Japanese Patent Laid-Open No. 57-
192281 is mentioned. This is on a titanium base,
Iridium oxide (IrC)2) and tantalum oxide (Tl1)
A conductive oxide layer such as niobium oxide (NbzOs) or tantalum oxide is formed as an intermediate layer between them at a concentration of 0.001 to 1 in terms of metal content.
These prior art technologies aim to save life by suppressing the progression of the electrode to a passive state, and
This is an attempt to save energy by lowering the electrode voltage.

However, in all of these methods, when forming a mixed oxide of multiple types of metals on a substrate, for example,
This method involves a firing step in which heating is performed for more than an hour, and electrodes manufactured in this manner have the problem of decomposing organic substances in various electrolytes.

Problems to be Solved by the Invention The present invention has been made in view of the above-mentioned eight problems of the prior art, and its purpose is to reduce energy consumption by e times. It is an object of the present invention to provide an electrode and a method for manufacturing the same that can have a long life, have a significantly reduced decomposition effect of organic matter compared to conventional techniques, and can improve manufacturing efficiency.

The present invention provides a mixture of iridium oxide (IrO2) and tantalum oxide (Taxes) in which the weight ratio of iridium to tantalum is in the range of 1:1.5 to 1:4. This electrode is characterized in that a film made of such a mixture selected from the following is formed on a titanium (Ti) base material.

Furthermore, the present invention provides iridium (Ir) and tantalum (Ta).
) was applied onto a titanium substrate, dried at about 120°C, the application and drying steps were repeated several times, and the solution was heated at 350°C to 400°C for 20 minutes in an oxidizing atmosphere. This is a method of manufacturing an electrode characterized by heating it.

Function According to the present invention, iridium (Ir) and tantalum (T
An alcoholic solution of each chloride in a) is applied onto a titanium substrate, dried, and heated at 350°C to 400°C in an oxidizing atmosphere. At this time, the compounding ratio of each chloride of ilinium and tantalum is such that the weight ratio of iridium and tantalum is 1:
1.5 to 1:4, electrodes manufactured in this way can reduce the applied voltage required to achieve an electrolysis rate equivalent to that of conventional techniques. .

In addition, the effect of oxidizing cations in the processing liquid in which such an electrode is immersed into multivalent ions is suppressed as much as possible, thereby significantly reducing energy consumption.

Further, such an electrode is suppressed from changing into a passive state, and can have a long life as an electrode.

Furthermore, even if the processing liquid contains various organic substances, they will not be decomposed, and therefore the processing liquid will be kept in a clean state.
Processing operations such as stopping the manufacturing line that includes the manufacturing process and purifying the processing liquid are suppressed as much as possible.This greatly improves work efficiency.

Example (1) This case? Example of manufacturing process for a-pole This electrode! In manufacturing, titanium metal (Ti
) is prepared. Iridium (
Ir) and tantalum (Ta) chloride (IrC, i'-
and TaCf5) in alcohol solution (solvent is meta/-
(You can use various alcohols such as alcohol, butanol, impropatul, etc.). At this time, the weight ratio of iridium (Ir) and tantalum (Ta) in the alcohol solution is selected in the range of 1:1.5 to 1:4. Thereafter, it is dried at a temperature of about 120°C, and then baked at a temperature of 350°C for 20 minutes. Repeat this coating process, semi-drying process, and baking process as many times as you want! Return it to manufacture the desired electrode.

(II)m1 Experimental Example (A) Experimental Content A 20% hydrochloric acid solution of iridium chloride (IrCf4) is evaporated, the resulting paste is dissolved in methanol, and then mixed with a methanol solution of tantalum chloride (TaC7s). Meanwhile, the titanium (T i ) base material to which the mixture is applied is polished, then surface treated with 7% hydrochloric acid at 70° C., washed with water, wiped with Kimwipe, and air-dried. The mixture was coated on the base material obtained in this way, heated at 120°C for 10 minutes to semi-dry it, and then heated to 350°C.
C. for 20 minutes. Such coating, drying and firing steps are repeated, for example, six times to obtain a thin film of about 1 μm on the titanium substrate. In this way, an electrode according to the present invention (hereinafter referred to as the present electrode) was obtained. Note that if the firing temperature is lower than 350° C., the mixture of iridium chloride and tantalum chloride will not be sufficiently oxidized, making it impossible to manufacture the desired electrode.

(a) Figure 1 shows the electrode manufactured in this way, depending on the blending ratio of iridium and tantalum and the firing temperature.
Was it manufactured by changing the blending ratio of iridium and tantalum and the firing temperature? Fig. 7 shows changes in the amount of carbon dioxide gas (CO2) generated by the anode when a quadrupole is used as the anode.

In Figure 1, Fin! 1~! 5 is firing temperature 550℃
, SOO°C, 450°C, 400°C, and 350°C, respectively. Also, in the graph, the vertical axis is charcoal l! ! 11 is the ratio of iridium to the total amount of iridium and tantalum (Ir/
(Blending ratio of iridium to total amount of Ir+ (Ir/(I
r+Ta), m11%).

This experimental example uses nickel sulfate N iSO, 6I4
50g/I of 20 and Na, WO, 'Fo of 2H20
g/J? Contains 90g/J of citric acid! An N1-W alloy plating solution containing a concentration of . In addition, the anode used has an area of 2 am'', and the current density is 20 A/d.
Current was applied with Il12 for 25 minutes, that is, with a charge amount of 600 coulombs.

As described in the section on the prior art, when organic substances such as citric acid contained in metallurgy are decomposed by such energization, carbonic acid is generated. The generation of such gas indicates the progress of decomposition of organic matter, and it is known that this causes deterioration of electrolytes such as plating solutions.

As shown in the present experimental example in Figure 1, ffl with an iridium blending ratio of 20 to 40% was used to suppress carbon dioxide gas generation.
It was also confirmed that good results could be obtained when the firing temperature was within the range of 350°C to 450°C within the range of the mixing ratio ffi.

FIG. 2 is a graph showing changes in anode voltage when several types of electrodes having different blending ratios of iridium and tantalum and firing temperatures are used as anodes when electrolyzing the aforementioned nickel-tungsten alloy plating solution.

The vertical axis of the graph shows the current density, and the horizontal axis shows the anode voltage 15 minutes after the start of energization. In the graph, line 16 corresponds to the case of a conventional electrode made of platinum, and line ! 7~. /
No. 14 has a combination of iridium and tantalum compounding ratio and firing temperature of (3 near, 450° C.) and (2:8.
400℃), (3 near, 400℃), (2:8.350
℃), (4:6,450℃), (4:6,400℃),
(4:6.350°C) and (3 near, 350°C).

As shown in PIS2 diagram, the combination of iridium and tantalum compounding ratio and firing temperature yields the best results in terms of reducing the anode voltage. 12 to 714, i.e. (4:
6.400°C), (4:6.350°C) and (3 near, 350°C). What should be noted here is that the electrode fired at 450° C. shows a relatively high anode voltage as shown by line 17.

Therefore, the firing temperature for the electrode that does not generate carbon N1 gas and is effective for reducing the anode voltage is 350 to 4
It was shown that 00°C is suitable and 450°C is not suitable as a firing temperature.

Table 1 below shows the results of measuring the operating life of electrodes with a firing temperature of 350°C to 400°C when used as anodes for nickel-tungsten alloy plating. A power supply voltage of 10V is connected between the and cathode, and the current density applied to the anode is set to 20A/20A with a variable resistor.
I set it to dsi2. In other words, when electricity is first applied, the voltage drop between the two electrodes is about 3V, but as electrolysis progresses, the electrodes are consumed and the iridium/tantalum oxide film on the titanium substrate is reduced, exposing the base material. As a result, the voltage drop between the two electrodes increases rapidly from about 3 cm to IOV.

This point was defined as the life span and was measured.

Table 1 Table 2 (Unit = Hours) As shown in the ftS1 table, the electrode fired at 400°C has the longest life. However, the electrode fired at 400"C has a long lifespan of about 50 hours before reaching the end of its life. It was confirmed that the decomposition of organic matter started.
The useful life of an electrode with an iridium to tantalum ratio of 4:6 is about 1,350 hours without any decomposition reaction of organic matter. On the other hand, it was confirmed that the electrodes fired at a firing temperature of 350° C. and a V of 380° C. did not decompose organic matter until the end of their life.

Therefore, from the measurement results of the organic matter non-decomposition performance, anode voltage, and life of the electrode shown in this experimental example, it can be concluded that the blending ratio of iridium and tantalum is preferably 2:8 to 4:6. Further, it is concluded that the firing temperature is preferably in the range of 350°C to 400°C. Among these, it was concluded that approximately 350°C to 380°C is the optimum firing temperature for an electrode that does not decompose organic substances until the end of its life.

(1) Mixed oxide of iridium and tantalum [! I
Regarding the thickness, in the experimental example described above, the mixed oxide layer was formed to have a layer thickness of about 1 μm. If this layer thickness is made too thin, a non-conductive oxide film will be formed on the surface of the titanium plate that is the base of the fired product.
A problem arises in that electrical resistance increases. On the other hand, the inventor of the present invention has confirmed that the above-mentioned effects can be obtained even with a layer thickness of about 10 μm in this mixed oxide film, but if the thickness exceeds about 50 μm, the fired product will electrically exhibit semiconducting properties. Therefore, a problem arises in that the conduction resistance increases.

Figure 3 shows the electrode potential and current density of the conventional platinum electrode and the present f'F electrode. ! 3 is a graph showing related characteristics. The vertical axis of the graph is the current density, the horizontal axis is the electrode potential, and the bath temperature is 65
Use a gold plating bath at ℃. Under these conditions? After energizing 600 clones, the conventional example and the present electrode were flashed, and the generated carbon dioxide and oxygen gas were collected and the amount of generation was measured, and the measurement results are shown in the fjrJ2 table below. Obtained.

As is clear from Table 2, Figure 3, the electrode of the present invention is indicated by the line /15 (the blending ratio of iridium and tantalum is 4:6, which is 35
0℃ firing temperature), the electrode potential is the conventional example (Line! 16)
It is confirmed that it is much lower.

Further, when comparing the amount of carbon dioxide gas generated, in this case, it is reduced to about 18.2% of the conventional example, which shows that deterioration of the electrolyte solution is suppressed to that extent.

Furthermore, when converting the measured total amount of generated large amount into oxygen gas as shown in Table 2 above, it is found that the carbon dioxide gas generated in the human body is generated by a two-electron reaction with the conventional platinum electrode.
Book f1. It has been confirmed that it is generated by a one-electron reaction at the electrode, so in the conventional example, 12+11/2=1'7.5cc...(4
) is obtained, and the amount of gas generated by the present electrode in terms of oxygen gas is 37 cc. Therefore, when using the conventional platinum electrode and the present electrode, the degree of oxidation reaction of ions in the electrolytic bath to multivalent ions as shown by the above equation fj & 1 is as follows:
In the conventional example, (38-17,5)/38X 100=54%
...It is about (5), and in this electrode, (38-37) / 38X 100 = 2.6%
−(6) is calculated. Therefore, regarding this point as well, by using the present electrode, the electric energy loss explained with reference to the second equation above can be reduced by 4 times compared to the conventional example.
．． This can be reduced to about 8%.

As described above, according to this embodiment, the degree of oxidation of gold ions into multivalent ions during gold plating can be reduced to about 1/25, and the degree of decomposition of objects can be reduced to about 115. can. Further, the electrode potential can be reduced to about 1/2, and the power cost can be reduced to about 2/3.

(I[[)Second Experimental Example In this experimental example, zinc sulfate (ZnSO= ・7H
20) 300g/7 and sodium sulfate (Na, SO,
) 100g/I, and adjust the hydrogen ion concentration to pH 1.2 with sulfuric acid (H, SO, ) 3'i! ! do. While maintaining such a plating bath at a liquid temperature of 60°C, a current density of O~2
0A/da'' condition.

The Pt54 diagram is a graph showing the anode potential when a conventional platinum anode and the present electrode of the number f1 type are used as the anodes used in the zinc plating performed in this manner. The vertical axis of the graph is the current density, the horizontal axis is the anode potential, and the line! 17 corresponds to the case of the conventional platinum anode, and line J!
18~J! 20 is the present anode, and the combination of the blending ratio of iridium and tantalum and the firing temperature is (8:2, 5).
00℃), (9:1,350℃) and (4:6.35
In the six experimental examples corresponding to the cases where the temperature was set to As is evident in the l't4 diagram, line 12
Indicated by 0! ! It is understood that the electrodes under the same conditions obtained the most favorable results.

Effects As described above, according to the present invention, an alcohol solution of each chloride of iridium (Ir) and tantalum (Ta) is applied and dried on a titanium base material, and then heated at 350°C to 4°C in an oxidizing atmosphere.
Heat at 00°C. At this time, the mixing ratio of each chloride of iridium and tantalum is selected such that the weight i ratio of iridium and tantalum is in the range of 1:1.5 to 1:4.
, the electrode manufactured in this way requires a lower applied voltage even when obtaining an electrolysis rate equivalent to that of the prior art. In addition, unnecessary oxidation of cations in the processing liquid in which such an electrode is immersed into multivalent ions is suppressed, thereby significantly reducing energy consumption.

Like this again? The pole is not! JJ! ! ! ! The change that becomes the state is suppressed, and? ! It is possible to extend the life of the pole. In particular, when various organic substances are contained in the processing liquid, the organic substances are not decomposed, and therefore the processing liquid is kept in a clean state.
The *3XL line, which includes the manufacturing process
! ! Processing work such as purifying the liquid becomes unnecessary. This greatly improves machining efficiency.

[Brief explanation of the drawing]

Figures 1 to 4 are graphs each explaining the characteristics of the present electrode. Agent Patent Attorney Kei Saikyo Figure 1! i2 combination ratio []r7'[r+Ta), 笈

Claims (1)

[Claims] (1) Iridium oxide (IrO_2) and tantalum oxide (
A coating is formed on a titanium (Ti) substrate, the mixture being a mixture of Ta_2O_5) and having a weight ratio of iridium and tantalum in the range of 1:1.5 to 1:4. An electrode characterized by comprising: (2) An alcohol solution of each chloride of iridium (Ir) and tantalum (Ta) is applied onto a titanium substrate, dried at approximately 120°C, and the application and drying processes are repeated multiple times in an oxidizing atmosphere. A method for manufacturing an electrode, characterized in that heating is performed at 350°C to 400°C for 20 minutes.