JPH0826473B2 - Electrodeposition method of amorphous iron-molybdenum-tungsten alloy coating. - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for electrodepositing an amorphous iron-molybdenum-tungsten alloy plating film.

[Problems to be Solved by Prior Art and Invention]

Although molybdenum and tungsten cannot be electrodeposited alone from an aqueous solution, they are known to be induced eutectoid metals that can be co-deposited with iron group metals. Alloy plating methods and iron-tungsten alloy plating methods have been proposed.

However, the conventional iron-molybdenum alloy plating method and iron-
Many of the plating films obtained by the tungsten alloy plating method have a crystalline structure, and an amorphous film is desired from the viewpoint of corrosion resistance and the like, but conventionally, there are few proposals for reliably obtaining such an amorphous film, There is no proposal for a method for obtaining an amorphous iron-molybdenum-tungsten ternary alloy plating.

The present invention has been made in view of the above circumstances.
It is an object of the present invention to propose a method for reliably and industrially electrodepositing a molybdenum-tungsten ternary alloy film.

[Means and Actions for Solving the Problems]

As a result of various investigations to achieve the above-mentioned object, the present inventors contain a water-soluble ferrous salt, a water-soluble molybdate, a water-soluble tungstate and a water-soluble tartrate as complexing agents. Using a plating bath having a pH of 3 to 6 and electroplating an object to be plated at a cathode current density of ² to 20 A / dm ² at a temperature of 50 ° C. or less, an iron content of 60% by weight or less and the balance of molybdenum and tungsten, or Amorphization is achieved by obtaining an iron-molybdenum-tungsten alloy plating film in which the amount of iron is 75% by weight or less, the amount of molybdenum is 15% by weight or more, and the balance is tungsten. It has been found that the molybdenum-tungsten alloy plating film has high corrosion resistance, and the above method can reduce the plating temperature, so that it has great cost advantages and is highly practical. It is a thing.

 Hereinafter, the present invention will be described in more detail.

The plating bath used in the method of the present invention contains the water-soluble ferrous salt, the water-soluble molybdate, the water-soluble tungstate, and the water-soluble tartrate as described above, and has a pH of 3 to 6.
belongs to.

Here, as the water-soluble ferrous iron salt, ferrous sulfate conventionally used for iron-tungsten alloy plating is used, and as the water-soluble molybdate salt, an alkali metal molybdate salt such as sodium molybdate is used. As the water-soluble tungstate, an alkali metal tungstate such as sodium tungstate is used, and as the water-soluble tartrate, ammonium tartrate, sodium tartrate, potassium tartrate, potassium sodium tartrate is used.

The concentrations of the above components are selected according to the intended plating film composition.In this case, the more molybdenum and tungsten in the plating bath, the more molybdenum and tungsten in the plating film. In the invention, the amount of iron in the plating film is 60% by weight or less from the viewpoint of amorphization, the balance is molybdenum and tungsten, or the amount of iron is 75%.
The plating bath composition is selected so that the weight is less than or equal to the weight, the amount of molybdenum is more than 15% by weight, and the balance is tungsten. Therefore,
From this point of view, the water-soluble ferrous salt is preferably 2-36 g / l, the water-soluble molybdate is 1-31.5 g / l, and the water-soluble tungstate is preferably 2-43 g / l. The water-soluble tartrate salt is preferably used so as to be equivalent to the total molar amount of ferrous salt, molybdate salt, and tungstate salt, and is usually 72 g / l or less.

 Further, the plating bath of the present invention is adjusted to pH 3-6.

When electroplating an appropriate object to be plated using the plating bath, the plating temperature is 50 ° C or lower, and more preferably
The temperature is 40 ° C. or lower, and in the present invention, plating can be sufficiently performed even at room temperature of 30 ° C. or lower. Further, the cathode current density can be set to ² to 20 A / dm ² .

The stirring may be unstirred, but it is preferable to use a stirrer or the like, and an insoluble anode such as a platinum-plated titanium mesh is usually used as the anode, but an iron anode can also be used.

 Next, the present invention will be described more specifically by way of examples.

〔Example〕

FeSO ₄・ 7H ₂ O, Na ₂ MoO ₄・ 2H ₂ O, Na ₂ WO ₄・ 2 as plating bath
Using H ₂ O and (NH ₄ ) ₂ C ₄ H ₄ O ₆ at the following concentrations, plating was performed at pH 3 to 8, plating temperature of 28 to 80 ° C., and cathode current density of ² to 20 A / dm ² .

In addition, a 500 ml glass cylindrical container was used as the electrolytic cell, a platinum plated titanium mesh (95 x 65 mm) was used as the anode, and a circular copper plate (6 cm ² x 0.3 ^t ) was degreased and pickled as the cathode (plating object). Used.

Furthermore, the X-ray diffraction method is used to determine the amorphous structure,
Fe, Mo and W in the electrodeposited film were analyzed by plasma emission spectrometry and fluorescence X
The linear method was used together. For the film structure, the distribution of constituents was determined using AES. For the electrochemical behavior of the electrodeposited film, an automatic polarization measuring device manufactured by Hokuto Denko was used.

(1) Fe-Mo-W various concentrations influence FeSO ₄ · 7H ₂ O of plating film _{composition, Na 2 MoO 4 · 2H 2} O, the Na ₂ WO ₄ · 2H ₂ O on the amorphous alloy film And a pH4 plating bath containing (NH ₄ ) ₂ C ₄ H ₄ O ₆ at a concentration of 72 g / l, plating temperature 30 ± 2 ℃, cathode current density 6.0 A / dm ²
The composition of the obtained plating film was analyzed, and it was evaluated whether it was amorphous or not. The results are shown in Fig. 1.

From the results shown in Fig. 1, the amount of Fe in the Fe-Mo-W alloy film was 60.
It was confirmed that an amorphous film can be obtained when the content of Mo is 20% or less, the amount of Mo is 20% or more, and the amount of W is the balance.

(2) Fe-Mo-W Effect of pH on the amorphous alloy film following composition _{FeSO 4 · 7H 2 O 36g /} l Na 2 MoO 4 · 2H 2 O 31.5〃 _{Na 2 WO 4 · 2H 2 O} 43 Use a plating bath of 〃 (NH ₄ ) ₂ C ₄ H ₄ O ₆ 72 〃 and change the pH to a plating temperature of 30 ±
Plating was carried out at various cathode current densities at 2 ° C., and it was evaluated whether or not the obtained plated film was amorphous. Results are shown in FIG.

From the results shown in FIG. 2, it was confirmed that when the plating bath was acidic, plating was possible and an amorphous film was obtained.

(3) Corrosion resistance of Fe-Mo-W alloy coating Fe-12% Mo-8% W and Fe-6% Mo-43% W plated coatings are immersed in 1N hydrochloric acid solution at 30 ° C, and anode polarization curve I asked. Results are shown in FIG.

From the results shown in FIG. 3, it was confirmed that the amorphous Fe-6% Mo-43% W alloy plating film had good corrosion resistance.

〔The invention's effect〕

According to the present invention, an iron-molybdenum-tungsten ternary alloy plating film which is amorphous and has excellent corrosion resistance can be electrodeposited reliably and industrially.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the relationship between the composition of the Fe—Mo—W alloy coating and amorphization, and FIG. 2 is the pH of the plating bath and the amorphousness of the Fe—Mo—W alloy coating. Fig. 3 shows various Fe-Mo-
The anodic polarization curve of a W alloy plating film in 1N hydrochloric acid is shown.

Claims (1)

[Claims] 1. A water-soluble ferrous salt, a water-soluble molybdate, a water-soluble tungstate, and a water-soluble tartrate.
Using a plating bath having a pH of 3 to 6 and electroplating an object to be plated at a cathode current density of ² to 20 A / dm ² at a temperature of 50 ° C. or less, an iron content of 60% by weight or less and the balance of molybdenum and tungsten, or A method for electrodepositing an amorphous iron-molybdenum-tungsten alloy coating, characterized in that an iron-molybdenum-tungsten alloy coating is obtained which has an iron content of 75% by weight or less, a molybdenum content of 15% by weight or more, and the balance being tungsten. .