JPH0397820A - Titanium alloy for anode - Google Patents

Abstract

PURPOSE:To provide the titanium alloy with a higher current capacity and higher corrosion resistance compared to those in pure titanium by specifying cobalt, nickel, elements of the platinum group and titanium. CONSTITUTION:The titanium alloy for an anode is formed from the comspn. constituted of, by weight, 0.05 to 3% cobalt and the balance titanium, or in addition to this, with 0.1 to 7% nickel, or furthermore in addition to this, with 0.01 to 5% elements of the platinum group. The above elements of the platinum group are selected from Pt, Au, Ru, Pd, Rh, Os and Ir. The above titanium alloy is used for an anode for electrolysis, in which a higher current capacity can be passed and corrosion resistance can furthermore be improved compared to pure titanium.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to anode materials, particularly anode materials for electrolytic manganese dioxide production, and other insoluble anode materials for plating and electrolysis.

[Conventional technology]

Graphite and lead are currently used as insoluble anodes. Platinum plating or platinum-talad titanium materials are used. However, graphite and lead are consumed by dissolution during use, causing contamination of the liquid.

On the other hand, platinum-plated or platinum-clad titanium materials are
The cost is very high due to the use of expensive platinum, and because the surface is coated with a small amount of platinum, the life of the die may be shorter than expected. Also,
In general, the surface of such surface-treated materials must be handled with care, and care must be taken when handling them.

In addition, the anode material used in the production of manganese is a pure titanium plate with a sandblasted surface because it is stable and wears much less than materials such as graphite. [Problem to be solved by the invention] However, when the current density of titanium anode materials is increased, the passive film on the surface may lengthen and the bath voltage may rise. There is a problem that electricity cannot be supplied. Therefore, it was necessary to suppress the current density during electrolytic manganese dioxide production to around 0.8 A/dm''.

This current density is a problem that is directly linked to productivity in electrolytic factories.If the current density is the same, the higher the current density, the more mass production is possible.If the production volume is constant, the higher the current density, the more The advantage is that equipment costs can be reduced. Furthermore, titanium is also used as an anode for materials other than anode materials for producing electrolytic manganese dioxide, but as mentioned above, when the current density is increased, a passive film grows on the surface, making it impossible to conduct electricity. A plated material is used. However, this type of treatment imposes a heavy economic burden due to the use of extremely expensive precious metals, which poses a major problem in terms of factory utilization. The present invention was made in view of the above-mentioned circumstances, and provides a completely new titanium alloy material for anodes, which is characterized by the ability to flow a higher current density and is inexpensive, in place of the conventionally used titanium anode material. It is intended to provide.

[Means to solve the problem]

In order to achieve the above object, the present invention has a cobalt content of 0.05
It is an anode material with a special feature that the content of cobalt is more than 3 wt% and the balance is titanium and unavoidable impurities, and the content of cobalt is more than 0.05 ωt% and less than 3 wt%.
Nickel is 0. It is an anode material with a content of 0.05 υt% and 0.05υt% of smooth cobalt.
Exceeding 3wt% or less, nickel 0.1wt% or more 7wt
% or less, platinum group elements (Pt, Au, Ru, Pd, Rh,
○The total content of s, Ir) is 0.01+, +t%
This is an anode material characterized in that the content is 5vt% or less, and the remainder consists of titanium and unavoidable impurities.

The present invention adds cobalt to titanium because Ti2C
This is because the intermetallic compound of o appears in the titanium by performing an appropriate manufacturing method, and by passing more current from this part, it prevents the growth of an oxide film on the base material titanium and prevents an increase in bath voltage. be.

At this time, if the amount of cobalt added is less than 0.05 wt%, the amount is small and is not much different from pure titanium, so the lower limit of the cobalt content was set to exceed 0.05 wt%. The upper limit was set at 3 wt% because if more than this amount is added, processing becomes extremely difficult and it is virtually impossible to process into the shape normally used as an anode material.

Furthermore, it was found that adding nickel to this resulted in an even more effective effect, leading to the discovery of the second invention of the present invention. At this time, if the cobalt content is less than 0.05 tit% and the nickel content is less than 0.1 wt%, the effect will not appear, so the lower limit of the cobalt content is set to 0.05 wt%.
exceeding the lower limit of nickel content. The upper wt% was set.

In addition, the upper limit of cobalt must be 3.5% in order to be able to practically process it into the shape normally used as an anode material.
It was necessary to set the upper limit of nickel to 7 wt%.

Furthermore, by adding a platinum-based element to this, more current can flow and the corrosion resistance is significantly improved, making it possible to use it without corrosion even in an electrolytic solution with a very harsh corrosive environment. This led to his discovery of his second invention.

At this time, Pt, Rh, Au, Pd, I r, Os, Ru
The lower limit of the total concentration of O. The reason for setting OLtzt% is that if it is less than that, no improvement in corrosion resistance can be expected, and the upper limit is set at 5wt%.
The reason for using the following values is that even if a larger amount is added, the effect is small compared to the economic burden. [Example] Next, the effectiveness of the present invention will be explained based on specific examples.

(Experiment 1) Pure cobalt and pure nickel were added to commercially available titanium sponge, and an ingot was made by vacuum arc melting. 90
Forging was performed at 0°C, then reheated at 900°C, and then hot rolled to produce a hot-rolled sheet with a thickness of 6 mm. This was processed into a thickness of 4 mm by cold rolling, and vacuum annealed at a temperature of 650° C. for 3 hours to obtain a test material.

The anode characteristic evaluation method for each sample material was 0.35 at room temperature.
Using platinum as the cathode and a puff-polished test material as the anode in an moQ/N phosphoric acid aqueous solution, the current density was 0. IA/
A dm constant current electrolysis test was conducted to determine how long it took for the bath voltage to rise to evaluate the anode electrode characteristics (see Figure 1).

Specifically, the time for the bath voltage to reach 5.0 volts was defined as the bath voltage rise time, and the anode electrode characteristics were evaluated based on the magnitude of this time. The table above shows Ti-Co binary alloys with 0.1 and 0.5 A/
The results of anode characteristic evaluation by conducting a current test at DM constant current are shown. As you can see from this table, if no cobalt is added at all (
No. 1: pure titanium), the bath voltage rise time is very short, whereas when the cobalt concentration exceeds 0.05%, the bath pressure rise time becomes longer and the anode = positive characteristics are improved. , From this, the lower limit of the amount of cobalt added is set to 0.
It can be seen that it is necessary to exceed 0.05 tit%. Also, as shown in the work table, the amount of cobalt is 3w
It was found that exceeding t% made processing extremely difficult, so the upper limit was set at 3wt%.Next. Table 2 shows the results of investigating the anode electrical properties of TiCo-Ni alloys.

First, the cobalt content is fixed at Q, 5t++t%,
The results of test materials with varying nickel contents are shown in No. 1
-No. 9, Table 1 T1 (bath voltage rise time of o binary alloy) The mark X indicates the bath voltage rise time of Ti-Co-Ni ternary alloy in Table 2 for materials in the range of the present invention alloy (1) * The marks indicate materials within the range of the invention alloy (2).As can be seen from these results, by adding Q.1wt% or more of nickel, the anode electrode characteristics begin to improve (bath voltage rise time becomes longer), especially when the nickel content is lv
It has been found that the content of nickel increases significantly when it exceeds t%.6 Based on this, the lower limit of the nickel content in the presence of cobalt is set to 0.1 wt%, preferably 1 wt%. Next, as a result of fixing the amount of nickel to 3 wt% and varying the content of cobalt, No. 10~No. As shown in No. 18, when cobalt is added to Ti-3%Ni in an amount exceeding 0.05 tit%, the anode electrolyte retention begins to increase, and in particular, it increases markedly when the cobalt content reaches 0.5 wt%. did.

At this time, the anode electrode characteristics become constant when the cobalt content exceeds 0.5 wt%, and even if more cobalt is added, the anode electrolyte retention hardly improves; on the contrary, when the cobalt content exceeds 3 wt%, It starts to decline.
From this, the lower limit of the cobalt concentration in the presence of nickel was set to exceed 0.05 wt%, and the upper limit was set to 3 wt%.

Finally, in order to determine the upper limit of nickel, the upper limit of cobalt concentration was set at 3 wt%, and as a result of increasing the nickel concentration,
No. 19 As shown below, it can be seen that increasing the amount of nickel tends to suppress the rise in bath voltage, but when the nickel content becomes 7 wt% when the cobalt content is 3 wt%, processing becomes extremely difficult. It has been found that processing is virtually impossible at 10 wt%. Therefore, the upper limit of nickel was set at 7t%.

As can be seen from the above experimental examples, compared to pure titanium, Ti-0.
It was found that more current can flow with CO exceeding 0.05vt% or 3wt%;
It became clear that more current could flow in Ti-0.05wt%-3wt%Co-0.1-7wt%Ni than in Ti-0.05wt%-3wt%Co, and an excellent anode material was obtained. ．． (Actual Example 12) In order to confirm how excellent the present alloy is as an anode material for electrolytic manganese dioxide production, pure cobalt was added to commercially available titanium sponge. After adding pure nickel and platinum elements and producing an ingot by vacuum arc melting,
Forging was performed at 0°C, then reheated at 900°C, and then hot rolled to produce a hot rolled plate with a thickness of 6 mm. This was processed into a thickness of 4 mm by cold rolling, and the temperature was 650'C.
After vacuum annealing for 3 hours, sandblasting was performed to prepare a sample material, and an evaluation test was conducted.

As shown in Figure 2, the evaluation test method was to first deposit manganese dioxide on the surface of the sample material by constant current electrolysis under conditions almost equivalent to actual operation, and then examine the rise in bath voltage at that time. We evaluated how high the current density could flow. As shown in Figure 2, the equipment used in this experiment is a 0.35 man/fla acid aqueous solution and a 0.55 mofl acid solution.
Manganese dioxide is precipitated on the surface of the test material by electrolyzing the test material at a constant current in a 95° C. water tank mixed with an aqueous solution of 1D dimanganese sulfur, using platinum as positive and negative, and platinum as positive and negative.

The criterion for this judgment was that if the bath voltage for 96 hours was 10 volts or less, manganese dioxide could be produced without problems at that current density.

Table 3 shows the test results obtained according to such IFR standards. As can be seen from this table, it is easy to see that the alloy of the present invention can pass a larger current than the pure titanium material (No. 1) currently used in actual operations.

From the above Experimental Examples 1 and 2, it was found that the material of the present invention has extremely excellent anode electrode properties, and can also provide even better corrosion resistance if necessary. (Experiment 3) In order to be used as an anode material even in a corrosive environment, higher corrosion resistance is required.
This problem was solved by adding a platinum-based element to t~7wt%Ni. Of course, it has been confirmed that adding the metal thread element does not reduce the amount of current that can be passed, and in fact allows more current to flow. In Table 4,
The changes in corrosion resistance when various platinum-based elements are added to Go-3wt%Ni exceeding T i −0.05ut% are shown. The test conditions were: corrosion of the sample material in Ryuki water, solution, and boiling.
was measured.

As can be seen from Table 4, the concentration of platinum-based elements is 0.01w.
When the concentration exceeds t%, an improvement in edibility is observed, and when the concentration exceeds 0.5vt%,
Above this level, an improvement in the edibility of drinking alcohol is clearly recognized. From this, the lower limit of the content of platinum-based elements is set to 0.0.
It can be seen that it is necessary to increase the content to 1wt%, preferably 0.5vt% or more. Furthermore, as the content of platinum-based elements increases, corrosion resistance improves, but after around 5 wt%, corrosion resistance stops improving for the amount added, and platinum-based elements are extremely expensive. Taking into account the above, the upper limit was set at 5 tit% due to the economic burden.5 It was found that the addition of platinum-based elements significantly improves corrosion resistance, but this does not mean that the corrosion resistance is actually used as an anode electrode, for example. Even if corrosion does not occur due to the anode corrosion protection effect when a potential is applied, corrosion may start immediately when the potential is no longer applied, such as when operations are stopped. The above alloys containing platinum-based elements are very effective.

The material of the present invention only needs to be present in a place where it comes into contact with the electrolyte, such as an electrode material that uses a dissimilar metal inside, such as a cladding or a welded joint, and where only the surface is made of the material of the present invention, or a material that is made by thermal spraying, etc. Naturally, the present invention also includes an electrode material which is surface-treated and then subjected to a diffusion treatment to form the alloy of the present invention.

〔Effect of the invention〕

According to the present invention described above, an anode material can be obtained that allows a much higher amount of current to flow than pure titanium, and has extremely high corrosion resistance. The alloy of the present invention, which has extremely excellent anode electrode durability, can be suitably used for industrial applications as an insoluble anode for plating, electrolysis, etc., and as an anode material for the production of electrolytic manganese dioxide. Hey,

[Brief explanation of drawings]

Figure 1 is a graph showing the change in bath voltage over time in @acid aqueous solution.
The second figure is an explanatory diagram of the manufacturing equipment for electrolytic manganese dioxide.

Claims (3)

[Claims] (1) Cobalt is more than 0.05wt% and less than 3wt%,
An anode material characterized in that the remainder consists of titanium and unavoidable impurities. (2) An anode material characterized in that cobalt is more than 0.05 wt% and 3 wt% or less, nickel is 0.1 wt% and 7 wt% or less, and the balance is titanium and inevitable impurities. (3) Cobalt is more than 0.05 wt% and less than 3 wt%, nickel is more than 0.1 wt% and less than 7 wt%, platinum group elements (
An anode material characterized in that the total content of Pt, Au, Ru, Pd, Rh, Os, Ir) is 0.01 wt% or more and 5 wt% or less, with the remainder consisting of titanium and inevitable impurities.