JPH01225792A - Electrodeposition bath stabilization method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention provides optical , relates to a method for stabilizing an electrodeposition bath to impart distinctive magnetic and mechanical surface properties.

The present invention can be used in a wide range of fields, such as automobiles, building materials, electrical equipment, containers, and magnetic recording media.

[Prior Art] It is known that a so-called secondary electrolytic coloring method is used to electrodeposit metal into the micropores of a porous alumite film of Au or A1 alloy. Alumite film, which is made by electrodepositing metal into micropores, is a beautiful film with excellent light resistance, corrosion resistance, and high surface hardness, and is widely used for interior and exterior A2 building materials. On the other hand, metal is deposited in micropores and electrically
Research on adding mechanical, optical, and magnetic functions is also active. For example, (1) When a magnetic metal is electrodeposited, a so-called magnetic alumite film exhibiting perpendicular magnetic anisotropy is formed, and a high-density magnetic recording medium is obtained. (2) When metal is electrodeposited into the fine pores of a thin alumite film of around 0.5 μm, it becomes a film that selectively absorbs sunlight. ■Electroless plating After electrodepositing a metal that can become a catalyst into the micropores, electroless plating is performed and the electroless plating metal is filled up to the openings of the micropores, forming an alumite film with conductivity. If this process is continued, an electroless plating film with good adhesion will be obtained on the alumite film. ■Lubricating properties and other properties can be imparted by changing the metal electrodeposited into the micropores into metal soap or metal sulfide.

All of these have Fe, Fe,
Ni, Go, Cu, Sn, 7. n, Pb,
In, Se, Ag.

(It is used by electrodepositing single metals or alloys such as LC, etc. Among them, Fe is low in cost, has few pollution problems, and does not deteriorate the properties such as corrosion resistance of the film. Ideal as a metal species for secondary electrolytic coloring.Also,
A magnetic layer electrolytically filled with Fe as an essential component exhibits excellent magnetic properties and is expected to be put to practical use.

[Problems to be Solved by the Invention] However, Fe2+ in the electrodeposition bath for electrolytically depositing Fe or Fe alloy into the fine pores of the alumite film is electrolytically oxidized at the anode or subjected to aeration oxidation to form F. It easily changed to e 3+ and had significantly poor bath stability. This causes a decrease in electrodeposition efficiency, poor control of color tone (due to insufficient filling and deposition of iron into micropores), and a decrease in the magnetic properties of the film, especially the saturation magnetic flux density (BS). Something happened.

FeJ+ is F during metal electrodeposition in alumite micropores.
The simultaneous reaction of e''+ e + Fe2+ causes a decrease in the electrodeposition efficiency.Fc3+ also has a metal etching effect, and it can damage the base aluminum in the alumite micropores before electrodeposition, and the metal that has been electrodeposited. It has the harmful effect of dissolving.

Addition of various reducing agents such as L-ascorbic acid has been used as a method to reduce Fc'+, which has such harmful effects, but this has the disadvantage of producing 8 products of these reaction products. Ta.

In addition, Fe, represented by organic acids and salts of organic acids, may be present in the electrodeposition bath.
2+ complexing agent is added to cause oxidation to Fe3+.
There have been attempts to stabilize the complexing agent, but as the treatment continues, the decomposition products of the complexing agent increase in volume and the Fe
This is not preferable as it becomes a factor that inhibits electrodeposition. In addition, it was not possible to completely prevent the oxidation of Fe''.Is it possible to prevent electrolytic oxidation at least at the anode by using a diaphragm method that separates the anode chamber and the cathode chamber for electrolysis using a diaphragm? 2
For the electrolytic waveform during the next electrolytic coloring, an AC or AC-like waveform allows for smoother electrodeposition than a DC or DC-like waveform, and the latter is used exclusively, so there is no advantage to using the diaphragm method. It is. Even if rHH deposition is performed using the diaphragm method using DC or a similar electrolytic waveform, the bath voltage will be high and the alumite film will be damaged (spalling).
This is not desirable as it tends to occur. Other problems with the diaphragm method include that the equipment is expensive and that oxidation of Fe2+ cannot be completely prevented.

In addition, the electrodeposition bath that electrolytically deposits metal into the fine pores of the alumite film is often used in a high pt+ region compared to normal electroplating, and it is better to use alternating current or a waveform similar to alternating current for electrolysis. Electrolytic deposition can be performed more smoothly than using a DC waveform. On the other hand, when alternating current electrolysis is performed in a low pH region, when the object to be treated is on the anode side, the metal electrolytically deposited in the 5 micropores will be redissolved, making it impossible to fill the electrodeposit sufficiently.

Therefore, it is desirable to conduct electrolysis in a high pH region.However, when electrolytic deposition is performed in a high pH region, as the metal ions in the electrodeposition bath are consumed, the pH of the electrodeposition bath tends to decrease. Electrodeposition baths containing Fc ions (hereinafter referred to as Fe-based electrodeposition baths) have large fluctuations. Fluctuations in pH have a large effect on magnetic properties, so constantly maintaining the pH within a certain range is the most important element in bath management. Generally, as a method of increasing the pH of a '1゛E plating bath,
Alkali metal hydroxides, their salts, ammonia, amines, etc. are used, but they are not suitable for metal electrodeposition into the micropores of an alumite film. That is, these PL+ adjusting agents are unsuitable because they cause destruction of the alumite film, ie, the so-called spalling phenomenon. Furthermore, the use of metal hydroxide as a bath component has a slow dissolution rate, and the insoluble hydroxide adsorbs to the surface of the film, inhibiting the electrolytic deposition of the metal into the fine pores, or preventing proper electrolytic deposition. Rapid and precise pH control is difficult, and implementation on an industrial scale has been impossible.

The present invention suppresses the formation of Fe3+ in an iron-based electrodeposition bath,
The present invention also aims to provide a new method that stabilizes the bath by suppressing pH drop and enables electrolytic deposition with stable quality.

[Means for Solving the Problems] The present invention, that is, a method for stabilizing an electrodeposition bath, uses Fe or Fe.
The metal Fe or Fe alloy is present in the form of lumps, granules, needles, powders, wires, cotton, plates, and foils in the electrodeposition bath of the alloy containing the metal. F in the bath by contact with
This is a method in which e3" is reduced to Fe2" and the pH is also controlled and managed.

The amount of Fe or Fe alloy to be dissolved and replenished each time varies depending on the type of bath, the amount of contact area of Fe or Fe alloy in the electrodeposition bath, the flow rate of the liquid, the bath temperature, etc. By determining and managing the relationship, the bath can be stabilized by balancing Fe consumption due to electrodeposition.

As shown in Figure 1, there is a method in which Fe or Fe alloy is allowed to coexist in direct contact with Fc-based electrodeposition in an electrodeposition bath, and as shown in Figure 2, an electrodeposition bath and a contact bath for Fe or Fe alloy are separated and independent. A method such as letting the water flow and circulating it can be applied.

Figure 1 shows the former method and shows the electrodeposition N! 11 is filled with an electrodeposition bath 2, and an electrodeposited object 3 and a counter electrode 4 are placed therein. A DC power source 5, an AC power source 6, or these alternately are connected to the object to be folded 3 and the counter electrode 4, and electrodeposition is performed. Electrodeposition bath 1 is separated from screen 7, and iron wire 8 and the like are supplied to the side where the electrode plate is not present. Further, FIG. 2 shows the latter method, in which a reactive species 9 filled with iron wire 8 and the like is provided, and the electrodeposition bath 2 is circulated by a pump 11 via a pipe 10. □ In general, in Fc electrolytic deposition, a reducing agent such as L-ascorbic acid is sometimes used in combination in the electrodeposition bath in order to suppress the production of Fe.11 Moreover, according to the present invention,
Since the consumption of these reducing agents is reduced, the amount added can be reduced or it may not be necessary to add them. In addition, the dissolution reaction of Fe or Fe alloy is caused by the already generated Fe3+
Since it also has a strong effect of reducing Fe2+ to Fe2+, it has an extremely large bath stabilizing effect.

Any type of electrodeposition bath can be effectively used as long as it contains Fe, including sulfuric acid baths, chloride baths, fluoride baths, sulfamic acid baths, organic acid baths, etc.

The metal iron sources used include pure iron, electrolytic iron, etc., as well as various other industrially produced and commercially available elements and components such as mild steel (for example, C, Mn, Si, etc.).

P, Fe5G, A9.203, etc.)
7) Te can also be used as long as it does not impair the electrodeposition properties. Further, when performing alloy electrodeposition such as Fc-Ni or Fe-Go, alloys containing appropriate amounts of Fe and Ni can be used as the iron source.

In addition, in the electrodeposition bath, Ni, Go, P, Mn, Or
, Cu, Sr.

The present invention can be effectively applied even if one or more of other components such as 11h, Re, c, o, and V are contained.

[Fe3+ in the action co-electrodeposition bath reacts with metal Fe, and itself becomes Fc
It is reduced to 2+, and the metal Fe is oxidized and eluted as Fe2+.

Most of the Fe'+ produced in the normal electrodeposition bath is the result of the reaction Fe2+→Fe"+e occurring at the anode during electrodeposition, but it may also be produced by aeration oxidation.

The reduction reaction by Fe dissolution of the present invention
→3 This is a reaction of Fc2+. This reaction causes Fe3+
It has the effect of lowering the ion concentration or suppressing the increase in the concentration, and at the same time replenishing Fe2+ in the electrodeposition bath, which has been reduced by electrodeposition. In addition, since the Fc'' reduction reaction by metal Fe is a diffusion-limited reaction of Fe3+ ions,
In order to promote the Fe"a photoreaction, it is effective to reduce the thickness of the reaction boundary film. Therefore, specific measures include stirring the electrodeposition bath, applying a fluidized tank or a packed tank, and improving the particle surface. It is extremely effective to increase the liquid flow rate of metal F.
As for e, it is also effective to reduce the reaction film by making the particles finer or smaller in diameter. On the other hand, in the electrodeposition reaction, the amount of free acid increases with the consumption of F e 2'' due to electrodeposition, that is, p
H decrease occurs. Here, in the dissolution reaction of Fe or Fe alloy, in addition to the reduction reaction of Fe3+, Fe+ 211"
Since the reaction of 4 Fe" + It2 also occurs, it also has the effect of suppressing the decrease in pH due to the consumption of hydrogen ions and stabilizing the pH.

As described above, as an effect of the present invention, Fe3 in the electrodeposition bath
Since it is possible to reduce ゝ and stabilize PL+ at the same time, it stabilizes the electrodeposition efficiency, the electrodeposition reaction, and the crystals of the deposited metal, significantly improving the quality of coloring and magnetic properties, and improving productivity and workability. There are advantages that can be achieved.

In particular, Na leaf and NH4011 are used to adjust the pH of the electrodeposition bath.
It has the feature of ensuring the integrity of the alumite layer because it eliminates the need for additions such as.

Further, the present invention has similar effects and functions not only when depositing iron particles but also when depositing alloys of iron and other elements, as long as a bath containing F c 3.

[Example] Table 1 shows examples of the stabilization of the electrodeposition bath according to the present invention and the resulting stabilization of the properties of the deposited film, together with comparative examples.

Table 1 shows the saturation magnetic flux density BS of the magnetic film in which iron is electrolytically deposited in the fine pores of alumite, Fe3+ before and after energization in the bath.
It is shown together with the concentration change and pH change.

As is clear from this table, according to the method of the present invention, the saturation magnetic flux density B8 after energization is higher than that of the comparative example.

[Effects of the Invention] According to the present invention, Fe" generated by electrodeposition is constantly reduced by the metal Fe in contact with the electrolyte bath, and
The 3+ concentration can be stably maintained at a low level.

In addition, iron ion supplementation allows the bath to maintain a desired level of pl+. Therefore, even if the amount of energized coulombs per unit volume of the electrodeposition bath increases due to the electrodeposition of Fe or Fe alloy, the same electrodeposition bath composition and electrodeposition characteristics as the new bath can be maintained.

Furthermore, since it is not necessary to add a pl+ regulator and a reducing agent to prevent Fe2+ oxidation to the electrodeposition bath, there is no accumulation of the additives and their reaction products in the bath.

As a result, it has become possible to stably form colored materials and magnetic films by electrodeposition. In particular, the electrolytic deposition of dense and homogeneous metal into the fine pores of alumite can be advantageously performed using the powder method, which has the advantage of allowing the pore depth to be increased, allowing for better control of color tone and magnetic properties of the magnetic film. There are characteristics that can be improved.

By significantly reducing the amount of electrodeposition bath waste, the cost of the electrodeposition process can be reduced.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are drawings each illustrating a method of bringing an iron wire or the like into contact with an electrodeposition bath. 1... Electrodeposition top, 2... Electrodeposition bath, 3... Electrodeposited object,
4... Counter electrode, 5... DC power supply, 6... AC (or AC similar) power supply, 7... Screen, 8... Iron wire, 9... Reaction tank, IO... Piping, 11...Pump, 12...Filter.

Claims (1)

[Scope of Claims] 1. In an electrodeposition bath in which aluminum or an aluminum alloy is anodized to form a porous alumite film, and iron or an iron alloy is electrolytically deposited in the fine pores, iron is added to the electrodeposition bath. Alternatively, a method for stabilizing an electrodeposition bath characterized by bringing an iron alloy into contact with the coexistence. 2. Iron or iron alloy is allowed to coexist in contact with the electrodeposition bath in the form of one or more of plate, foil, wire, cotton, block, granule, needle, and powder. Claim 1
Method for stabilizing the electrodeposition bath described.