JPH04365828A - Titanium alloy for anode - Google Patents

Abstract

PURPOSE:To produce a Ti-based insoluble anode usable at high current density in electrolysis, etc., by adding Ni, other specified metallic elements and Pi family elements to Ti. CONSTITUTION:A Ti alloy anode as an insoluble anode for producing electrolytic manganese dioxide, an insoluble anode used at the time of electroplating with various metals or an insoluble anode used in various electrolytic devices is made of a Ti alloy contg. 0.1-7wt.% Ni and 0.01-5wt.%, in total, of Al, V, Cr, Mn, Cu, Zn, Zr, Nb, Mo, Cd, In, Sn, Te, Hf, Ta, W and Pb or further contg. 0.01-2wt.%, in total, of Pt family metals such as Pt, Au, Ru, Pd, Rh, Os and Ir. Electric current can be supplied to the resulting insoluble anode without forming a passive film even at high current density.

Description

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

[Conventional technology]

Currently, graphite, lead, platinum plating,
Alternatively, platinum-clad titanium material is used.

However, graphite and lead are consumed by melting during use, causing contamination of the liquid.

On the other hand, platinum-plated or platinum-clad titanium materials,
The disadvantage is that the cost is very high due to the use of expensive platinum. Therefore, since the surface is slightly coated with platinum, the lifespan may be shorter than expected, and such surface-treated materials generally have the disadvantage of requiring careful handling of the surface.

Furthermore, the anode material used in the production of electrolytic manganese dioxide is a pure titanium plate whose surface has been sandblasted, because it is stable and wears much less than materials such as graphite.

[Problem to be solved by the invention]

However, the titanium anode material has the problem that when the current density is increased, a passive film grows on the surface and the bath voltage increases, and if it is attempted to continue the current flow, the current flow eventually becomes impossible. Therefore, it was necessary to suppress the current density during electrolytic manganese dioxide production to around 0.8 A/dm2.

This current density is a problem that is directly linked to productivity in electrolytic plants.If the current density is the same, the higher the current density, the higher the mass production possible.If the production volume is constant, the higher the current density, the higher the This has the advantage of reducing equipment costs.

Furthermore, titanium is also used as an anode material other than the anode material for producing electrolytic manganese dioxide, but as mentioned above, when the current density is increased, a passive film grows on the surface and it becomes impossible to conduct electricity. Those plated with noble metals such as platinum plating are used. However, as mentioned above, such treatment requires the use of very expensive precious metals, which imposes a heavy economic burden and poses a major problem in terms of industrial use.

The present invention has been made in view of the above circumstances, and provides a completely new titanium alloy material for an anode electrode, which is characterized by being able to flow a higher current density in place of the conventionally used titanium anode material. The purpose is to

[Means to solve the problem]

In order to achieve the above object, the present invention
．． 1 wt% or more and 7 wt% or less, A■, V, Cr, Mn
, Cu, Zn, Zr, Nb, Mo, Cd, In, Sn,
The total concentration of Te, Hf, Ta, W, and Pb is 0.0
It is characterized in that it is 1wt% or more and 5wt% or less, with the remainder being titanium and unavoidable impurities, and 0.1wt% or more of nickel.
wt% or more and 7wt% or less, A■, V, Cr, Mn, C
u, Zn, Zr, Nb, Mo, Cd, In, Sn, Te
, the total content of Hf, Ta, W, and Pb is 0.01
Platinum group elements (Pt, Au, R
The total content of u, Pd, Rh, Os, Ir) is 0.
．． This is an anode material characterized in that the amount is 01 wt% or more and 2 wt% or less, with the balance being titanium and unavoidable impurities.

The present invention adds nickel to titanium because Ti2N
This is to prevent the growth of an oxide film on titanium, which is the base material, and to prevent an increase in bath voltage by precipitating the intermetallic compound i in titanium and passing more current through this portion. In this way, even if nickel is added alone to titanium, more current can flow than pure titanium, but in order to achieve a sufficient effect, it is necessary to add a considerable amount of nickel.

However, if a large amount of nickel is added to titanium, the workability will be greatly reduced, and in the worst case, processing (rolling) will no longer be possible. In order to improve these points, the present inventor investigated the effects of a large number of additive elements, and finally discovered the effects of nickel, A, V, Cr, Mn, Cu, Zn, Zr, Nb, Mo.
, Cd, In, Sn, Te, Hf, Ta, W, and Pb, it was found that by simultaneously adding at least one element from among them, a large amount of current could be passed while suppressing the amount of nickel. , the first invention of the present invention has been discovered.

The reason why the present invention sets the nickel content to 0.1 to 7 wt% is because if it is less than 0.1 wt%, only the same amount of current as pure titanium can flow, and the upper limit is set at 7 wt%.
% because if titanium contains more nickel than this, processing becomes extremely difficult and manufacturing becomes virtually impossible.

Also, A■, V, Cr, Mn, Cu, Zn, Zr, Nb
, Mo, Cd, In, Sn, Te, Hf, Ta, W, P
The reason why the total content of b is set to 0.01 to 5 wt% is that if it is less than 0.01 wt%, a significant improvement in the amount of current that can be passed cannot be expected due to the synergistic effect with nickel. The reason for this is that even if the content is increased further, the effect will hardly improve.

Furthermore, by adding platinum-based elements to this, it was found that more current could flow and corrosion resistance was significantly improved, making it possible to use it without corrosion even in electrolytic solutions, which are extremely corrosive environments. As a result, the second invention of the present invention was discovered.

In addition, the lower limit of the total content of Pt, Rh, Au, Pd, Ir, Os, and Ru was set at 0.01 wt% because corrosion resistance could not be improved if it was less than that, and the upper limit was set at 2 wt% or less. This is because even if more than this 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.

(Example 1) Commercially available titanium sponge with pure nickel, A, V, Cr
, Mn, Cu, Zn, Zr, Nb, Mo, Cd, In,
After adding Sn, Te, Hf, Ta, W, and Pb and producing an ingot by vacuum arc melting, it was forged at 900°C, then reheated at 900°C, and then hot rolled to reduce the thickness. A 6 mm hot rolled plate was produced. 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 m at room temperature.
o ■/■ Using platinum as the cathode and buffed test material as the anode in an aqueous sulfuric acid solution, a constant current electrolysis test was conducted to find out how long it took for the bath voltage to rise.
The anode electrode characteristics were evaluated (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.

Table 1 shows Ti-Ni-A■, V, Cr, Mn, Cu, Z
n, Zr, Nb, Mo, Cd, In, Sn, Te, Hf
, Ta, W, and Pb through current conduction tests at constant currents of 0.5 and 2.0 A/dm2.

From this table, No. It can be seen that when no additive metal is added, as in the sample material No. 1 (pure titanium), the bath voltage rise time is extremely short. Furthermore, No. 2 or less No. The test materials up to No. 18 are titanium with A■, V, Cr, Mn, Cu, Zn,
Zr, Nb, Mo, Cd, In, Sn, Te, Hf, T
It is an alloy in which the metals a, W, and Pb are added, respectively.
In both cases, the current carrying properties are comparable to those of pure titanium, and no improvement is seen.

On the other hand, alloys made by adding nickel to titanium show clearly improved current carrying characteristics compared to pure titanium (No.
．． 20 and no. 21), No. Nickel and A■, V, Cr, Mn, Cu, Zn, Zr,
Nb, Mo, Cd, In, Sn, Te, Hf, Ta, W
, the titanium ternary alloy to which Pb metal is added is Ti-Ni
The current can be passed for a longer time than the alloy without increasing the bath voltage, and the improvement in current carrying properties is clearly seen (However, as in No. 22, even if it contains 1% A■, the Ni content is , it is not effective at less than 0.1wt%)
.

This shows how the alloys within the scope of the present invention have excellent anode properties.

It goes without saying that the alloy within the scope of the present invention did not corrode during this test.

Table 2 shows A■, V, Cr, Mn, Cu, Z for Ti-Ni.
n, Zr, Nb, Mo, Cd, In, Sn, Te, Hf
, Ta, W, and Pb. All alloys have improved current conductivity characteristics than pure titanium as well as Ti-Ni alloys, including A■, V, Cr, Mn, and C.
u, Zn, Zr, Nb, Mo, Cd, In, Sn, Te
, Hf, Ta, W, and Pb are sufficiently effective.

(Example 2) In order to confirm how excellent the alloy of the present invention is as an anode material for producing electrolytic manganese dioxide, commercially available sponge titanium was mixed with pure nickel, A, V, Cr, Mn,
Cu, Zn, Zr, Nb, Mo, Cd, In, Sn, T
After adding e, Hf, Ta, W, and Pb and producing an ingot by vacuum arc melting, forging at 900°C, then reheating at 900°C and hot rolling to a thickness of 6 mm.
A hot rolled sheet was produced. This was cold rolled to a thickness of 4 mm.
After vacuum annealing at a temperature of 650° C. for 3 hours, a sandblasting treatment was performed to prepare a sample material, and an evaluation test was conducted.

As shown in Figure 2, the evaluation test method is to precipitate manganese dioxide on the surface of the sample material by constant current electrolysis under conditions almost equivalent to actual operation, and to investigate the rise in melting voltage at that time. We evaluated whether a high current density could be passed. The apparatus used in this experiment was 0.0 mm as shown in Figure 2.
In a 95°C water bath containing a mixture of a 35 mo ■/■ sulfuric acid aqueous solution and a 0.55 mo ■/■ manganese sulfate aqueous solution, the test material was subjected to constant current electrolysis using the anode as the anode and platinum as the cathode to coat the surface of the test material. It precipitates manganese dioxide.

As a criterion, if the bath voltage for 96 hours was 8 volts or less, it was considered that electrolytic manganese dioxide could be produced without problems at that current density.

The test results obtained according to these criteria are
Shown in the table. As can be seen from this table, pure titanium material (No. 1) and Ti-N material are used in current actual operations.
It can be easily seen that the alloys of the present invention can pass more current than the i-alloys (Nos. 2 to 4).

From the above, it was found that the material of the present invention has extremely excellent anode electrode characteristics as an anode material for producing electrolytic manganese dioxide.

(Example 3) In order to be used as an anode material in a very severe corrosive environment, it is necessary to be able to flow a large amount of current and at the same time to have very high corrosion resistance. Therefore, the first alloy of the present invention contains platinum group elements (Pt, Au, Ru, Pd, Rh).
, Os, Ir).

Of course, it has been confirmed that adding a platinum group element does not reduce the amount of current that can be passed, and in fact allows more current to flow.

Table 4 shows changes in corrosion resistance when various platinum group elements were added to the Ti-0.5% Cu alloy. The test method was to measure the corrosion loss of the test material in an aqueous sulfuric acid solution at 95°C, and calculate the corrosion rate from it.

As can be seen from Table 4, the concentration of platinum-based elements is 0.01w.
At t% or more, corrosion resistance is improved, and at 0.5wt%
Above that, the improvement in corrosion resistance is clearly seen. This lowers the lower limit of the content of platinum group elements to 0.01w.
It can be seen that it is necessary to make the t% preferably 0.5wt% or more.

Furthermore, as the content of platinum group elements increases, corrosion resistance improves, but after around 5 wt%, corrosion resistance stops improving for the amount added, and platinum group elements are extremely expensive. Considering this, the upper limit was set at 5 wt% due to the economic burden.

As mentioned above, it has been found that corrosion resistance is significantly improved by adding platinum group elements, but this is because, for example, when an anode potential is actually applied as an anode electrode, even if corrosion does not occur due to the anodic corrosion protection effect, Corrosion may begin immediately when a potential is no longer applied, such as when the operation is stopped, and in such cases, the above-mentioned alloys containing platinum group elements are extremely 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 only the surface of which is made of the material of the present invention, or an electrode material such as a thermal sprayed material. Naturally, the present invention also includes an electrode material that is surface-treated and then subjected to a diffusion treatment to form the alloy composition 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 having such excellent anode electrode characteristics can be suitably used for industrial purposes as an insoluble anode for plating, electrolysis, etc., and as an anode material for electrolytic manganese dioxide production.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing changes in bath voltage over time in an aqueous sulfuric acid solution, and FIG. 2 is an explanatory diagram of an apparatus for producing electrolytic manganese dioxide. Agent Tetsuro Abe

Claims (2)

[Claims] Claim 1: Nickel content is 0.1 wt% or more and 7 wt% or less, A■, V, Cr, Mn, Cu, Zn, Zr, Nb,
Mo, Cd, In, Sn, Te, Hf, Ta, W, Pb
An anode material having a total content of 0.01 wt% or more and 5 wt% or less, with the remainder consisting of titanium and unavoidable impurities. [Claim 2] Nickel is 0.1 wt% or more and 7 wt% or less, A■, V, Cr, Mn, Cu, Zn, Zr, Nb,
Mo, Cd, In, Sn, Te, Hf, Ta, W, Pb
Platinum group elements (Pt, Au, Ru, Pd, Rh, Os,
Ir) total content is 0.01wt% or more 2wt
% or less, the remainder consisting of titanium and unavoidable impurities.