JPS58199839A - Surface-activated amorphous alloy for cathode for electrolysis - Google Patents

Abstract

PURPOSE:To obtain a surface-activated amorphous alloy for a cathode for electrolysis capable of consuming electric power effectively and stably by preparing an amorphous alloy consisting of a specified percentage of P, Si, B or C and the balance Ni or Co and by activating the surface of the alloy. CONSTITUTION:A molten alloy consisting of 4-35 atomic% one or more among P, Si, B and C and the balance Ni and/or Co is very rapidly cooled at >=about 10<4> deg.C/sec cooling rate to manufacture an amorphous alloy. In order to increase the activity of the alloy as a cathode for electrolysis, Zn or the like is diffused in the surface layer of the alloy and leached out with an alkali soln. to activate the surface. By the activation the amorphous alloy is provided with superior characteristics as a material for a cathode for electrolysis.

Description

Detailed Description of the Invention The present invention provides an electrolytic amorphous alloy cathode Kl with a low hydrogen overvoltage, sufficient durability and corrosion resistance, and an activated surface.
It is something to do.

Conventionally, iron electrodes have been used in water electrolysis or electrolysis of aqueous alkali chloride solutions in which hydrogen generation reaction is the main reaction at the cathode. Iron is inexpensive as a cathode material, and also exhibits a fairly low hydrogen overvoltage.
-Late maturation, and there is a need to further improve this.

Usually, alloys are crystallized in the solid state, but if the alloy composition is limited and rapidly solidified, an amorphous structure similar to that of a liquid without a crystalline structure can be obtained even in the solid state. Such alloys are called amorphous alloys.

＼ This amorphous alloy has significantly higher strength than conventional metals, and exhibits various properties depending on its composition. Furthermore, a process in which Zn or the like is diffused into the surface layer of an alloy and then leached out to promote the special properties of the alloy is called surface activation treatment. The present invention uses an amorphous alloy that has undergone such treatment as an electrolytic cathode.The present invention provides an amorphous alloy that has excellent performance as an electrolytic cathode, such as being able to use electric power effectively and stably. The purpose is to provide the following.

The present invention consists of the following two inventions.

Surface active amorphous alloy for electrolytic cathode containing 4 to 55 atoms of any one or more of p, si, B and C, and the remainder consisting of one or two of Ml and Co. .

1 Contains 4 to 35 atoms of any one or more of P, Si, B and C, and II
45jiL children - less than 1 0u, Mo, Or, Mn and V -
m or two or more types, 55 atoms or less, Mj, one or more of Zn and 8n, 40 atoms or less4 Pt, Ru, Rh, P (any one of 1, Xr, Mg, and Au, or 1 group or 9 selected from 2 or more and 50 or less atoms contains 65 or less atoms in the total amount of two or more groups, and the substantial balance is one type of N1 and CO containing 15 or more atoms. Maku is a surface-activated amorphous alloy for electrolytic cathodes that contains two types and has a total of 100 atoms.

In the present invention, the amorphous alloy obtained by ultra-rapidly solidifying the bath alloy having the above composition is a single-phase alloy in which each element is uniformly contained in the same bath. Originally, in order to impart selective activity to a metal electrode for a specific chemical reaction, it is necessary to prepare an alloy containing the required amount of effective elements. However, crystalline metals have a multi-phase structure with many different types, and for this reason, mechanical strength is often difficult to obtain. On the other hand, the amorphous alloy of the present invention has an amorphous structure created by ultra-quenching from a liquid state, always forms a homogeneous phosphorous solid solution, and has excellent mechanical properties and corrosion resistance. Shows stable and uniform electrode characteristics.

Furthermore, in order to increase the activity as a cathode for electrolysis, it is necessary to perform a surface activation treatment such as diffusing and penetrating Zn into the alloy surface layer and then leaching this with an alkaline solution. In crystalline metals, diffusion and infiltration of Kn, etc. mainly occurs at grain boundaries, so if Zn, etc. is subsequently leached, the crystal grains will fall off from the metal surface, and the metal will only become brittle, and surface activation may not be effective. many. On the other hand, since the amorphous alloy of the present invention is not crystalline, it naturally does not have grain boundaries, and not only does it not suffer from embrittlement due to preferential diffusion and penetration of Zn etc. into the grain boundaries. Essentially Z
Because the diffusion rate of Zn and other elements is fast, Zn and other elements diffuse into the entire surface layer of the alloy even when treated at a relatively low temperature, and then by leaching it out, the surface is sufficiently activated and an amorphous alloy is formed. This is the reason why it has excellent properties as a cathode material for electrolysis.

Incidentally, the diffusion and penetration of Zn and the like can be achieved, for example, by heat treating the alloy in Zn powder, or by applying zinc plating to the alloy and then heat treating it.

In this case, since the heat treatment temperature is <, crystallization of an amorphous alloy activates the surface, so K is a good friend, and as crystallization progresses, the alloy may become brittle. It is desirable to avoid the progression of

Next, a method for producing an amorphous alloy according to the present invention will be explained.

An amorphous alloy can be produced by ultra-rapidly cooling an alloy bath having the composition of the present invention from a molten state at a cooling rate of about 0.4° C./second or more.

If the cooling rate is as slow as about 10407 seconds, complete amorphization cannot be achieved. Therefore, as long as such ultra-rapid cooling can be achieved, it is possible in principle to produce the amorphous alloy of the present invention using any type of equipment.

As an example, Fig. 1 shows an apparatus for producing the amorphous alloy of the present invention.
In Figure 0 shown in Figure 0, 2 is a quartz tube having a nozzle 3 vertically at its lower end, and a raw material 4 and an inert gas for preventing oxidation of the raw material are fed through an inlet 1 provided at the upper end of this quartz tube 2. can do. A heating furnace 5 is provided around the quartz tube 2 to heat the sample 4. A high-speed rotating roll 7 is provided vertically below the nozzle S, and is rotated by a motor 6. For production of amorphous alloy #i raw material 4t-1 quartz tube with predetermined composition 2. Heating furnace 5 under inert gas atmosphere
The molten metal is heated and melted by a motor 6.
．． Goo ~1 (If the pressurized inert gas is injected onto the outer circumferential surface of the roll 7 rotating at high speed at L mouth OQr, p, m, the gas will be thick, for example, LO5■.

The amorphous alloy of the present invention can be obtained as a long thin plate with a width of 10 mm and a length of several meters.

The amorphous alloy of the present invention produced by the above method has a surface activated (?,...) crystalline N1 etc. by the same method.
Hydrogen gas generation overvoltage, small I, high, crystalline N1
In contrast, the hydrogen gas generation overvoltage of the surface-activated amorphous alloy of the present invention does not increase even if used for a long time, whereas the It hardly ever changes and is extremely stable.

Therefore, the surface-activated pre-amorphous alloy of the present invention has excellent performance such that electric power can be used effectively and stably as a cathode in water electrolysis or aqueous alkali chloride solution electrolysis.

Next, the reason for limiting the component composition in the present invention will be described.

When the total of one or more of P, 1iii, B and C is less than 4 atoms or more than 35 atoms, it becomes difficult to obtain an amorphous structure. Therefore, P,
81. The total amount of one or more of B and C must be in the range of 4 to 35 atoms, and in particular, an amorphous structure can be easily obtained when it is 16 to 25 atoms.

N1 and Go are the basic elements of the amorphous alloy of the present invention, and are effective elements for amorphization and corrosion resistance, and are extremely effective in surface activation treatment in which 4Zn etc. is diffused and then leached out. It is an element. Therefore, in the second term of the present invention, from among N1 and COO -
It is necessary that the total number of at or two types is 15 or more atoms.

IPe is an element that is inexpensive and facilitates amorphization, but when added in large quantities, it reduces the diffusion rate of Zn and other substances during surface activation treatment, making it difficult to diffuse and penetrate below the crystallization temperature. Addition of a large amount of oxidation gas makes it more likely to absorb hydrogen and become brittle when used as an electrolytic cathode. e must be kept to 65 atoms or less.

Ou, Mo, Cr, Mn, and V are all effective elements that improve the corrosion resistance of amorphous alloys in acid and alkaline solutions.Addition of an appropriate amount promotes amorphization, but addition of a large amount This results in amorphous formation, which causes problems, and also makes the amorphous alloy susceptible to embrittlement during rounding and surface activation treatments, which lower the crystallization temperature of the amorphous alloy. Therefore, in the second item of the present invention, Ou, Mo, Or.

Among Mn and V, the total of 9 types is 2 or more types is 55
It is preferable to keep it below Itsuko Chi.

When Zn and 8nFi are activated, when leaching Zn etc. with an alkali solution, activation is further promoted because 8n is leached out from the amorphous alloy base. However, when added in a large amount, the crystallization temperature of the amorphous alloy decreases, and during surface activation treatment, it becomes brittle and becomes rounded.
It is preferable that the total amount of one or more of these is 40 or less.

Pt, Ru, Rh, PI, Ru, Mug, and Mu are all elements that enhance the electrocatalytic ability in the hydrogen generation reaction and significantly improve the corrosion resistance of amorphous alloys, but they are very expensive. In the second aspect of the present invention, Pt,
It is preferable that the total of one or more of Ru, Rh, P(1, Cr, Mug, and Au) is kept to 50 atoms or less.

In addition, a, os, te, Zr, Wb,
Elements such as Ta stabilize the amorphous structure, and addition of less than 50% does not impede the purpose of the present invention.

Next, the present invention will be explained in more detail by examples.
The present invention is not limited to these examples.

Example 1 An alloy of a predetermined composition is heated in bales and ultra-cooled to a thickness of 20~
An amorphous alloy thin plate with a width of 50 μm and a width of a5 to 7 was obtained. These amorphous alloy thin plates were cut to a specified length, and 9
0% zinc sulfate, 90% sodium sulfate, 30% salt, 1
a pi consisting of 8% boric acid [4, 1 in a water bath solution at 20 °C]
Zinc plating was carried out at a constant current density of 200°C to 200°C, followed by heat treatment at 200-500°C for 1 hour to diffuse and infiltrate the zinc. leached and used this as a sample electrode,
90°C, 50 mV/in 52-sodium hydroxide solution
Cathode polarization is achieved using the potentiodynamic method of changing the potential transfer speed of win.
Mourning in search of a line. (As an example, in Table 2, in 52-sodium hydroxide solution at 90°C, determine the electrode potential exhibiting a cathodic current density tt of 10 μm/dIl from the potentiodynamic polarization !1lls and write it down.

The surface-activated amorphous alloy of the present invention exhibits a lower potential than the crystalline, IF, Ni shown as a comparative example, and has an extremely excellent hydrogen gas generation catalytic capacity. Furthermore, as shown in Table SK, the surface was activated under the same conditions as in the present invention)
TiFi exhibits excellent hydrogen gas generation catalytic ability at the beginning of electrolysis, but the potential gradually shifts to a less noble direction, whereas the surface-activated amorphous alloy of the present invention has an excellent initial running electrode potential. It is stable with no fluctuation. This is because the surface activation of crystalline alloys occurs mainly at grain boundaries, and as the electrolysis time progresses, the activated layer disintegrates and falls off.
This shows that the mechanical stability of the surface activated layer of the amorphous alloy is extremely excellent. Therefore, it can be said that the surface-activated amorphous alloy of the present invention has an extremely excellent hydrogen gas generation catalytic ability as a cathode for water electrolysis, and also has excellent electrode stability.

Example 2 Using a sample electrode prepared in the same manner as Example 1, 80C
, the potentiodynamic cathodic polarization curve was measured in a pHi4.4M saline solution. Table 4 shows potentials representing cathodic current densities of 10 mu/ga determined from these potentiodynamic polarization curves as potential differences based on the potential of crystalline Fe determined in a similar manner.

A positive potential difference means that the hydrogen gas generation overvoltage is smaller than that of crystalline νe, and the surface-activated amorphous alloy of the present invention has a positive potential difference of 1 compared to crystalline i[Fe.
It has a low hydrogen sludge generation overvoltage of 50 to 200 mV, and therefore can be said to be an excellent cathode material that can generate hydrogen gas extremely efficiently as a cathode for alkaline salt solution electrolysis.

Table 2: Zinc diffusion treatment [1] was applied at 2500°C, and then Zn
Hydrogen gas generation potential at 10 μm/diK was measured in a sodium hydroxide solution at 90°C for 32 s using a surface-activated sample by leaching HgO. -lNNa
0H) Invention alloy 11 -t095 Mu 2 -1105 Jf65 -L116 Mu 4 -4145 Mu 5 -t104 Jl,! -t117 Tsuta 7 -1105 A 8 -t09B Mu? -t113 410 -1.094 411 -1.125 Ji12 -1.136 Mu13 -1.090 414 -tot8 Bian15 -1.112 416 -1.064 Mu17 -1084 41B -tllo 419 -1.094 420 -toas 421 -1.062 Flat 22 -1.093 A25 -1.066 Todoroki 24 -t059 Hire 25 -t078 Comparative example Crystalline IPe -t274e N
i -1285 090℃, potential V in 52℃ NaOH bath solution: H
gO/Hg-1M NaOH Table 4 Zinc was diffused and penetrated at 500°C, then Zn was leached out, the activation line was measured on the surface, and the cathode current density of 7' (10A〆V) was determined from these recommended curves. The potential shown by the crystal [Fa sample 10~F?Cathode current density'fK potential difference with crystalline Fe (7) JP & 1 + α190 μm 2
+(1170m 5
+α150 A4 +(Ll, 20 ivy 5
11178 Mu6 +α145 A7 +(L185 Mu6 +1190 Mu9 +α146 Todoroki 10 +1194 A11 +α125 Mu12 +α112 Mu13 +α201 Mu14 +a182 .415 +1152414
+(L207Ji, 17
10α190418 +0.143mu1
9 +112 414 +α196 421 +(1202I622
+α195ya23 +
α209 424 10 α214, ≦25
10201

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of an apparatus for producing the amorphous alloy of the present invention. 1... Raw material and inert gas inlet 2... Quartz tube S... Nozzle section 5... Heating furnace 6... Motor 7... ^ Speed rotating roll Patent applicant Toyo Soda Kogyo Co., Ltd. '1:

Claims (1)

[Claims] (1) P, 81. Contains 4 to 55 atoms of one or more of B and C, and the remainder is Ml
A surface-activated amorphous alloy for an electrolytic cathode consisting of one or both of Co and Co. (21F, 81. Contains 4 to 35 atoms of any one or more of B and C, and 11
Fe means 65 atoms or less I; one or more of Cu, Mo, Or, Mn and V, 55 atoms or less 3) Mu4. -m or two or more of Zn and 8n, 4
0 atoms - 4) Pt, Ru, Rh, P(1, Ir, Mug
9 is the total amount of two or more groups, containing 65 atoms or less, and the substantial remainder is 15 1 or 9 of Ml and COO of atomic strength or higher include two species,
A surface-activated amorphous alloy for electrolytic cathodes having a total of 100 atoms.