JPH1060683A - Electroplating with ternary system zinc alloy, and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably obtain a zinc alloy electroplating film, excellent in resistance to corrosion, wear, and scratch, by specifying compositional ratio among zinc, nickel, and cobalt. SOLUTION: This ternary system zinc alloy electroplating film has a composition consisting of, by weight, 70-90% Zn, 8-18% Ni, and 2-16% Co. In order to obtain this plating film, three soluble electrodes, consisting of metals of Zn, Ni, and Co respectively, are disposed in a plating tank 10 and these are dissolved by power supply via rectifiers 14, 16, 18, respectively, in a proportion corresponding to the precipitation ratio in the plating film. A material 20 to be plated is hung into a plating bath 19 and electrolysis is performed in the presence of metal ions in the prescribed ratio to carry out plating. As to Ni content in the alloy composition, surface hardness cannot be improved when Ni content is below the lower limit, and, when it exceeds the upper limit, corrosion resistance is deteriorated rather than improved. Zn content is regulated to a value in the above range for the purpose of utilizing the corrosion resistance of Zn. Sufficient brightness of precipitated alloy plating film cannot be obtained if Co content is below the lower limit, and also corrosion resistance cannot be improved even if it exceeds the upper limit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a ternary zinc alloy obtained by performing electroplating and a method for electroplating the same. More specifically, the present invention provides zinc, nickel,
The present invention relates to an electroplating alloy of a ternary zinc alloy comprising iron and cobalt and an electroplating method for obtaining the same.

[0002]

2. Description of the Related Art Conventionally, electroplating zinc has been widely used and used industrially as a corrosion-resistant plating film.
Due to its excellent economics, the application field is ever expanding.

[0003] However, as the field of application expands, more advanced properties are required, and nowadays better corrosion resistance and also better abrasion resistance and scratch resistance to prevent damage to the plating film. Is required. As one solution to satisfy such demands today, it is conceivable to convert the plating film into a multi-component alloy.

[0004] A large number of binary zinc alloy platings have already been known so far.
Iron alloys, zinc-copper alloys, zinc-nickel alloys, zinc-cobalt alloys, and the like have been practically used.

Further, as a ternary zinc alloy plating, for example, tin-copper-zinc alloy plating has been known for decorative purposes, and 17% Ni as a corrosion-resistant plated steel sheet.
A 0.3% Co-Zn plated steel sheet is known.

[0006]

However, these conventional binary and ternary zinc alloy plating films have low surface hardness and have the following problems as a plating method. During electroplating, it was difficult to keep the metal ion concentration in the plating bath constant, and the ratio of deposited metal could not be uniform or was difficult.

In order to obtain a smooth and glossy electrolytic deposition plating film from a solution containing multiple metals, a large amount of organic additives must be used, and therefore, purification of decomposition products of organic compounds in the plating bath must be performed. There is a problem that it needs to be performed periodically, and the generated wastewater causes environmental pollution.

It is an object of the present invention to develop means which can solve the above-mentioned problems in the prior art. More specifically, an object of the present invention is to provide more excellent corrosion resistance, and more excellent wear resistance to prevent damage to a plating film,
An object of the present invention is to develop a zinc alloy electroplated film having excellent scratch resistance and an electroplating method capable of stably obtaining the same.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted various studies focusing on the diversification of the plating film as a means for solving such an object, and as a result, compared with conventional zinc plating, for example, by weight%. , Zinc: 82%, nickel: 11%, cobalt:
The ternary zinc alloy electroplated film having a composition ratio of 7% has a surface hardness of 500 Hv or more, and has a corrosion resistance of 1,400 hours or more as measured by a neutral salt spray test.
The present invention was completed when it was found that an unexpected improvement such as ~ 10 times was made.

[0010] Here, the present invention relates to a method in which zinc:
It is an electroplated ternary zinc alloy having a composition ratio of 90%, nickel: 8 to 18%, and cobalt: 2 to 16%. Also,
From another aspect, the present invention provides an electrode composed of each metal of zinc, nickel, and cobalt, and performs power supply dissolution in accordance with a deposition ratio of each metal by a plating bath, and in the presence of a predetermined ratio of metal ions. This is a method for electroplating a ternary zinc alloy of zinc, nickel, and cobalt, wherein the plating is performed by electrolysis.

Here, "electroplated ternary zinc alloy" means a ternary zinc alloy formed by an electroplating method, specifically, a plating film made of a ternary zinc alloy.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic explanatory view of a plating method according to the present invention. In the drawing, a plating tank 10 is provided with three soluble electrodes 12 and corresponds to each plating metal. Soluble electrodes made of metal are provided, and rectifiers 14, 16, 18 at a ratio corresponding to the deposition ratio in the plating film, respectively.
Power is melted through.

An object 20 to be plated, which is, for example, an iron-made automobile part, is suspended from a plating bath 19 in the plating tank 10, and is given a motion such as rotation as necessary. Next, the reason why the alloy composition and the manufacturing conditions of the plating film are limited as described above in the present invention will be described in detail together with the operation. In this specification, "%" indicating the alloy composition is "% by weight" unless otherwise specified.

Nickel: If less than 8%, no improvement in surface hardness is observed, and the intended effect cannot be exhibited, while if more than 18%, the corrosion resistance is rather reduced. Preferably, it is 9 to 15%.

Zinc: The plating film according to the present invention basically utilizes the corrosion resistance of zinc. For this purpose, the zinc content is set to 70 to 90%. Preferably, 75-
85%.

Cobalt: 2-16% of cobalt is added as a third constituent metal. If it is less than 2%, sufficient gloss of the deposited alloy plating film cannot be obtained, and if it exceeds 16%, no further improvement in corrosion resistance can be seen, and the cost rises. Preferably it is 3 to 14%.

Bath temperature: The temperature of the treatment bath is preferably from 30 to 50 ° C. If the temperature is lower than 30 ° C, the electrodeposition rate is low and the current density may not be sufficiently increased. Is unfavorable because the composition balance is lost.

Building bath: The ternary zinc alloy plating according to the present invention can be obtained by performing electrolytic plating by using a plating bath containing each constituent metal element in the form of ions.
As long as the plating bath composition itself is not limited, plating baths that can be effectively used in the present invention include, for example, first, chloride of each metal is converted to pH using boric acid and sodium acetate.
Was prepared by dissolving in a prepared aqueous solution. Other plating baths are not particularly limited as long as each metal ion is uniformly dissolved.

According to one embodiment of the present invention, the plating bath is adjusted by an individual feeding melting method. Conventionally, an additive such as a polyamine derivative / alkyl or allyl ethoxylate / cyclic aldehyde has been used in the bath. However, in the case of the present invention, it is not necessary to use such an additive. Absent.

Conventionally, power is generally supplied by a single electrode, and even in the case of electroplating of a binary alloy, the amount of melting is not individually controlled by controlling the current individually. Even in the case of alloy plating, supply in the form of a metal salt has been mainly used.

However, according to the present invention, a single electrode is formed from each of the three kinds of metals, which are constituent elements of the alloy, and is supplied and melted at a predetermined composition ratio. According to a preferred embodiment of the present invention, after preparing the plating bath, the three kinds of metals constituting the electrodes may be individually set and melted in accordance with the consumption of each of them.

For example, in the case of a plating film of 82% of zinc, 11% of nickel, and 7% of cobalt, such individual melting currents are, for example, 2.3 A / dm ^{2 for} zinc, and 0.2 for nickel.
4 A / dm ² , cobalt: 0.3 A / dm ² .

As described above, according to the present invention, since no organic additive is contained in the bath, the accumulation of impurities generated by decomposition in the bath during the plating period is reduced, and the plating bath needs to be purified on the way. It can be used stably for a long time without using. In this regard, in the conventional method, decomposition products accumulate due to electrolysis, which requires periodic purification treatment, which not only complicates the operation, but also significantly increases environmental measures such as disposal of waste generated by the purification treatment. Was a factor. Thus, the electroplated ternary zinc alloy according to the present invention has the following corrosion resistance and surface hardness.

Corrosion resistance * Plating film hardness Hikarizawa Conventional zinc plating (100% Zn) 100 hours ca 100Hv Yes (with organic additives) Conventional zinc / nickel alloy plating (95% Zn, 5% Ni) 1000 hours ca 400Hv Yes (with organic additives) Ternary zinc alloy plating (82% Zn, 11% Ni, 7% Co) 1400 hours ca 500Hv Yes (without organic additives) (Note): * Results of SST test.

The following effects are also obtained with respect to the manufacturing method. B) Conventional plating bath compositions consisted of metal salts plus organic additives.However, by using a ternary alloy, a uniform electric analysis can be performed without using these organic additives unexpectedly. A coating is obtained.

B) In order to continuously maintain the composition of the alloy, three types of electrodes (zinc, nickel, and cobalt) for supplying metal are kept in the bath, and each of them is separately energized (supply of a dissolution current corresponding to the deposition composition). ) Can maintain a predetermined metal concentration in the bath. Next, the operation and effect of the present invention will be described more specifically with reference to examples.

[0027]

【Example】

(Conventional example) As a conventional example, electroplating was performed using a plating bath having the following bath composition. Conventional example 1 Zinc chloride bath Zinc chloride 40 g / l Ammonium chloride 200 g / l Metas ZB627A * 30 ml / L 〃 ZB627G * 1 ml / L pH 5.5 Cathode current density 3 A / dm ² Bath temperature 30 ° C.

Conventional Example 2 Alkali alloy bath Zinc oxide 15 g / l (Zn / Ni) Caustic soda 130 g / l METASU AN-NI * 100 ml / L (containing Ni) 〃 AN-A * 20 ml / L 〃 AN- B * 10 ml / L Cathode current density 3 A / dm ² Bath temperature 20 ° C.

Conventional Example 3 Alkali alloy bath Zinc oxide 25 g / l (Zn / Fe) Caustic soda 120 g / l Metas AFZ-1 * 120 ml / L (containing Fe) 〃 AZA-5 * 25 ml / L 〃 AZB- 10 * 2 ml / L Cathode current density 3 A / dm ² Bath temperature 20 ° C (Note) *: Brightener (leveling agent) manufactured by Yuken Industry Co., Ltd. The characteristics of the plating thus obtained were evaluated. The results are summarized in Table 1.

(Embodiment) In this embodiment, the plating apparatus shown in FIG. 1 is used to form a plating film composed of 70 to 90% of zinc, 8 to 18% of nickel, and 2 to 16% of cobalt for an iron-made automobile part. Ternary alloy electroplating having

First, a plating bath is composed of acidic to neutral zinc hydrochloride (zinc chloride), nickel hydrochloride (nickel chloride), boric acid, and sodium acetate, and zinc-nickel-cobalt is formed at a bath temperature of 45 ° C. Ternary zinc alloy plating was performed.

For controlling the bath composition, a power supply system was used in which zinc, nickel, and cobalt were each used as an electrode serving as a counter electrode of the object to be plated, and a closed circuit was formed so that power could be supplied separately from each other. The bath composition of the comparative example was as follows.

Comparative Example Ternary alloy plating bath Zinc chloride 55 g / l Nickel chloride 95 g / l Sodium chloride 146 g / l Boric acid 31 g / l Sodium acetate ゛ 3H ₂ O 41 g / l The bath composition was as shown in Table 2. The properties of the plating film thus obtained were evaluated. Table 3 summarizes the results.

As can be seen from these results, all of the ternary alloys of the examples have a hardness of 400 Hv or more and a hardness of 10 H
Corrosion resistance of 00 hours or more is ensured, especially in Example No. 1,
In Nos. 2 and 5, hardness of 500 Hv or more, which cannot be obtained by conventional zinc plating, zinc-nickel and zinc-iron alloy plating, gloss as a plating film, and corrosion resistance of 1400 hours or more in salt water test. It is understood that three kinds of plating characteristics can be obtained at the same time.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

[Table 3]

[0038]

As described in detail above, according to the present invention, a plating film having high hardness and improved corrosion resistance by 5 to 10 times as compared with the conventional zinc plating can be obtained. The present invention is of great practical significance, as it can be applied as an environmentally friendly zinc alloy plating required today because no additives are required.

[Brief description of the drawings]

FIG. 1 is a schematic illustration of the method of the present invention.

Claims (2)

[Claims] 1. Zinc: 70 to 90% by weight, nickel:
An electroplated ternary zinc alloy having a composition ratio of 8 to 18% and cobalt: 2 to 16%. 2. An electrode is formed from each of zinc, nickel, and cobalt, and is subjected to power supply dissolution by a plating bath in accordance with a deposition ratio of each metal, and electrolysis is performed in the presence of a predetermined ratio of metal ions. A ternary zinc alloy electroplating method of zinc, nickel, and cobalt, characterized by plating by plating.