JPH01298192A - Zinc-nickel alloy plating solution - Google Patents

Abstract

PURPOSE:To prepare a plating soln. easily giving a Zn-Ni alloy plating film having a high Ni content and high corrosion resistance by adding specified amts. of Zn<2+>, Ni<2+>, an amine chelating agent and triethanolamine and an effective amt. of a brightener. CONSTITUTION:An alkaline cyan-free Zn-Ni alloy plating soln. of about >=13pH contg. 5-20g/l Zn<2+> and 0.4.-4.0g/l Ni<2+> in 4-12.5 weight ratio of Zn<2+> to Ni<2+> is prepd. The plating soln. further contains >=0.04mol/l one or more kinds of amine chelating agents selected among N-aminoethylethanolamine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine, 15-60g/l triethanolamine and an effective amt. of a brightener such as a quat. pyridine compd. The plating soln. gives a Zn-Ni alloy plating film having about 10-16% Ni eutectoid rate, superior corrosion resistance and uniform fine specular gloss.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a zinc-nickel alloy electroplating solution. The present invention relates to a zinc-nickel alloy plating solution that can apply alloy plating to articles with complex shapes.

[Conventional technology]

Zinc-nickel alloy plating has superior corrosion resistance compared to zinc plating, and is therefore widely used as anticorrosive plating for steel products. In particular, it is known that an alloy plating film with a nickel content of 10 to 16% is made of a γ single-phase alloy and has the best corrosion resistance. Therefore, zinc with a nickel content in this range -
Many proposals have been made to stably obtain nickel alloy plating (Japanese Unexamined Patent Publications No. 55-110791, No. 55-15).
2194. 57-164999゜58-9997.
58-55585. 58-197292, 59-
80789. 59-123782, 60-1069
92. 60-228693, etc.). However, all of these methods are for continuous plating of flat steel plates, and cannot be used for complex-shaped mechanical parts.

Conventionally, plating solutions for applying zinc-nickel alloy plating to general mechanical parts with complex shapes, etc.
Broadly divided, there are sulfuric acid baths, chloride baths, pyrophosphate baths, cyanide baths, and cyanide-free alkaline baths, each of which has its advantages and disadvantages, but in Japan, cyanide-free alkaline baths are preferred because they are easier to manage and cause less equipment corrosion. , tend to be preferred over other baths.

A cyanide-free alkaline bath for applying zinc-nickel alloy plating to general mechanical parts, etc. is disclosed in Japanese Patent Application Laid-Open No. 58-34 [89]
, No. 62-238387, No. 62-240788, etc. These baths contain both nickel and 47r
It is quite excellent in terms of rate uniformity and plating appearance. However, these conventional plating solutions were not satisfactory in terms of the nickel content in the resulting alloy plating. In other words, as is well known, zinc-
In Ninokel alloy plating, the nickel content is 10-
It is known that excellent corrosion resistance is achieved when 16% of the γ phase is precipitated as a single phase, but the conventional cyanide-free alkaline plating solution for general use described above is not suitable for corrosion-resistant zinc-nickel alloys containing such a high percentage of nickel. cannot be precipitated. Therefore, the nickel eutectoid rate in zinc-nickel alloy plating, which is currently being carried out industrially for mechanical parts used in boats, is also about 5 to 10%.

[Problem to be solved by the invention]

In view of the fact that the conventional zinc-nickel alloy plating solution had the above-mentioned problems, the purpose of the present invention is to
The object of the present invention is to provide a cyanide-free alkali bath plating solution that easily provides highly corrosion-resistant zinc-nickel alloy plating with a nickel eutectoid ratio of 10 to 16%.

[Means to solve the problem]

The present invention achieves the above object by making the composition of a cyanide-free alkaline zinc-nickel alloy plating solution as follows.

Zn2+25~20y/l Ni": 0.4~4, 0 g/l but Zni!+/Ni2" (weight ratio)
is 4 to 12.5.

One or more amine-based clearing agents selected from the group consisting of N-aminoethylethanolamine, ethylenediamine, diethyltriamine,]-lyethyleneatramine, tetraethylenepentamine, and pentaethylenehexamine: total amount 0.04 mol/l or more Triethanolamine = 15-60 H/l Brightener - Use an appropriate amount depending on its uniform electrodeposition effect.

In order to achieve the objective listed in -F, this composition requires not only the content of Zn'' and N12+, but also the selection and blending ratio of additives to stably dissolve nickel ions in the strongly alkaline plating solution. This is based on the fact that the present inventors found through experiments that this is extremely important.

That is, although both the chelating agent and triethanolamine used in the present invention have been individually used in conventional zinc-nickel alloy plating solutions and zinc plating solutions, in order to achieve the purpose of the present invention, they must not be used. It is essential to use them in combination as described above. It has also been confirmed that particularly favorable results can be obtained by using specific brighteners.

To explain in more detail the composition of the plating solution of the present invention, the main ingredient Zo'' is supplied from Zn0, ZnS
O+・7H20, Z nc I□, Ni2+ supply sources include N i(OH)2, N i COs, N15O,
・61-(20, NiC1, ・6H20 and other salts can be used. If Zo2+ is less than 5 g/l, it is not suitable for practical use!-Cathode current efficiency cannot be obtained, and 20 g
If it exceeds /l, a uniform glossy plating appearance cannot be obtained.

When the Zo''/Ni2+ ratio is less than 4, although a uniform and glossy plating appearance can be obtained, the nickel eutectoid ratio exceeds 16%, which not only deteriorates the corrosion resistance but also is economically disadvantageous. Also, this ratio is about 12.
If it exceeds 5, the low current area becomes matte plating, and the nickel eutectoid rate becomes less than io%, resulting in poor corrosion resistance.

The concentration of the amine chelating agent in the plating solution is 0.
If the amount is less than 0.04 mol/l, NI2+ cannot be sufficiently solubilized. Also, this concentration is at most about 0.5 mol/
l is appropriate, and even if it exceeds it, the effect will not change.

When the concentration of triethanolamine is less than 15 g/l, a good bright plating appearance is obtained in the high current area, but the plate becomes matte in the low current area.

On the other hand, if it exceeds 601/l, although a uniform and excellent shiny plating appearance can be obtained over a wide current density range, the cathode current efficiency deteriorates, making it unsuitable for practical use.

The brightener used in the plating solution of the present invention is
1. Brighteners conventionally used for zinc plating and cyanide zinc plating can be used as appropriate, and there are no restrictions, but among them, the reaction products of amines and epichlorohydrin, aromatic aldehydes, quaternized Pyridine compounds and the like are particularly suitable for use in the plating solution of the present invention in that they provide particularly excellent bright plating.

pll is not particularly limited, but is preferably about 13 or more.

The standard usage of the zinc-Ninokel alloy plating solution of the present invention is as follows.

Cathode current density: 0.5~8Δ/dra” Anode current density
1 to 8 A/dm2 Bath temperature: 15 to 35°C Anode: Zinc can be used as a soluble anode, and carbon, stainless steel, nickel, etc. can be used as an insoluble anode.

Metal replenishment: Zinc is melted from the anode or added with ZQO, nickel is NiSO+6H20,
NiC1□・6 HxO,, N + (OH)2, Ni
This is done by adding C03.

〔Example〕

The present invention will be described below with reference to Examples and Comparative Examples.

All plating in the following examples was performed using a 267 m1 Hull cell, and the plating conditions were as follows.

Current = 2A Plating time: 5 minutes Bath temperature: 25°C (35°C only in Comparative Example 2) Anode: Zinc cathode Nibrite steel plate Example] Bath composition: NaOH1.30g/II, ZnO12,
5g/1t (10g/l as Zo), N Is
Ot・6 HzO6,7g/l (1.5g/l as Ni
il, Zn/N1=6.67), ethylenediamine I
J# (0,166 mol/l,) reethanolamine 3
0g15. , Brightener/Spar 80 (brightener for cyanide zinc plating manufactured by Ebara Nishilight Co., Ltd.: containing a quaternized pyridine compound as the main ingredient) As a result of the 4 ml/l Hull Cell test, a uniform specular gloss appearance was observed over the entire surface of the test piece. Obtained. The nickel eutectoid rate at the center of the specimen is 14.2
%Met.

In addition, this plating solution was used to plate a steel plate with a thickness of 5 μm, and then a colored chromate treatment (Ebara Nishilight Co., Ltd. Soucro, mate treatment agent 7N-IIYM [I 50m1/
I+) was applied. Separately, similar plating and talomate treatment were performed using the plating solution of Comparative Example 2 described later. When a salt water spray test was conducted on each of the treated steel sheets I, it was found that white rust developed in the comparative example 2 after 480 hours, while white rust did not develop in the material according to this example even after 2000 hours. I couldn't admit it.

Example 2 Bath composition: Ethylenediamine in Example I was changed to diethylenetriamine lO/1l (0,097 mol/II).

As a result of the Hull cell test, a uniform specular gloss appearance was obtained over the entire surface of the specimen. The nickel eutectoid rate at the center of the test piece was 13.4%.

Example 3 Bath composition: The ethylenediamine in Example 1 was changed to triethylenetetramine 25/α (0,171 mol/l).

As a result of the Hull cell test, a uniform specular gloss appearance was obtained over the entire surface of the specimen. The nickel eutectoid rate at the center of the test piece was 13.5%.

Example 4 Bath composition: The ethylenediamine of Example 1 was replaced with tetraethylenepentamine l Og#l (0,053 mol/It )
Change it to .

As a result of the Hull cell test, a uniform specular gloss appearance was obtained over the entire surface of the specimen. The nickel eutectoid rate at the center of the test piece was 15.8%.

Example 5 Bath composition: Ethylenediamine in Example 1 was changed to pentaethylenetetramine 10 g/α (0,043 mol/l).

As a result of the Hull cell test, a uniform specular gloss appearance was obtained over the entire surface of the specimen. The nickel eutectoid rate at the center of the test piece was 11.0%.

Example 6 Bath composition: Ethylenediamine of Example 1 was mixed with N-aminoethylethanolamine 10 c/l (0,096 mol/l)
II).

As a result of the Hull cell test, a uniform specular gloss appearance was obtained over the entire surface of the specimen. Moreover, as shown in FIG. 1, almost no change in the nickel eutectoid rate due to a difference in distance from the low current side of the Hull cell plate (ie, a difference in cathode current density) was observed. The plating thickness at each part on the Hull Cell board was as shown in Figure 2.

Example 7 Bath composition: NaOH40c/l, ZnO6,25c/l (
5 H#) as Zn, N iC12・6 H20
1, 62g/4 (0.41/l as Ni, Z port/
Ni-12,5), N-aminoethylethanolamine 5/II (0,048 mol/l), triethanolamine 30 g/l, brightener LX-5OR (manufactured by Ebara Nishilite Co., Ltd. for zincate galvanizing) Brightener;
Contains a reaction product of amine and epichlorohydrin and an aromatic aldehyde)F++l/I) As a result of the Hull cell test, a specular glossy appearance was obtained over the entire surface of the test piece, although the cathode current efficiency was not very good. The nickel eutectoid rate at the center of the test piece was 12.0%.

Example 8 Bath composition: NaOH 130t/l, ZnO 20g/I
t (lex/1 as Zn>, Nrc+□・6
Hzo 10 g/ρ (2.5 c/l as Ni, Z
n/N1=6.4), N-aminoethylethanolamine 20gInc0.19 mol/]), Tri-Ethanol 9/
-Luami 7 40 g/11. Brightener LX-5OR
As a result of the 5ml #Hull Cell test, a specular glossy appearance was obtained over the entire surface of the test piece. The nickel eutectoid rate at the center of the test piece was 14.3%.

Example 9 Bath composition: N! OH130t/l1. Zn0 1
2.5c/l (10!/11 as Zn), N
iClz・6 Hz 10 g#t (2 as Ni
．． 5t/l, Zn/N1=4.0), N-aminoethylethanolamine 21/l (0.19 mol/g).

Triethanolamine 15g/M, brightener/LX-5O
As a result of the R5ml/fi Hull cell test, a specular glossy appearance was obtained over the entire surface of the test piece. The nickel eutectoid rate in each part of the test piece was the first
As shown in the figure.

Comparative Example 1 The same bath composition as in Example 9 was used except that triethanolamine was not blended.

As a result of the Hull cell test, although specular gloss was obtained in the medium and high current areas, the plating was matte in a range of 2 cm from the low current side. The nickel eutectoid ratio in each part of the test piece is as shown in FIG.

Comparative example 2 (acidic bath) Bath composition: ZnCIz 1 oot/a, NiC
l2・61120140c/l, NH,CI 200
c/l, brightener 2N-5OMU (manufactured by Ebara Nishilight Co., Ltd.) 50ml/l, brightener 2+1-60 (
(manufactured by Ebara Nishilight Co., Ltd.) 2 at/e.

As a result of the pH 5, 6 Hull cell test, a specular gloss appearance was obtained over the entire surface of the test piece, but the nickel eutectoid rate in each part of the test piece was
As shown in Figure 1, the change was large on the low current density side. Furthermore, as shown in FIG. 2, the plating thickness also changed significantly with changes in current density.

Comparative Example 3 In Example 1, 10 g of ethylenediamine was mixed with 30 g of disodium ethylenediaminetetraacetate (0,088
It was changed to mol/litre.

As a result of the Hull cell test, although a specular gloss appearance was obtained over the entire surface of the test piece, the nickel eutectoid rate at the center of the test piece was 2.6%.

Comparative Example 4 The composition was the same as in Example 1 except that the brightener Spar 80 was not added.

As a result of the Hull cell test, the nickel eutectoid rate at the center of the specimen was 13.9%, but the appearance was dark gray and matte.

〔Effect of the invention〕

As is clear from the results of Examples and Comparative Examples, the zinc-nickel alloy plating solution of the present invention enables zinc-nickel eutectoid plating with a nickel eutectoid ratio of lO to 16%, which was extremely difficult with conventional plating solutions. Moreover, --like nickel eutectoid occurs over a wide range from the low current part to the high current part. As a result, the zinc-nickel alloy plating obtained using the plating solution of the present invention exhibits much better corrosion resistance than the conventional low nickel eutectoid ratio zinc-nickel alloy plating. The plating solution of the present invention not only has an excellent nickel eutectoid rate, but also has the advantage of providing a plating film that is uniform in thickness over a wide current density range and has a beautiful specular gloss.

As mentioned above, according to the present invention, high-quality zinc-nickel alloy plating, which was impossible with conventional plating solutions, is possible, and it can greatly contribute to improving the quality of industrial materials, machine parts, etc. It is.

[Brief explanation of the drawing]

FIGS. 1 and 2 are graphs showing the test results of Examples and Comparative Examples. Fig. 1 Distance from low current part of Hull cell plate (c++) Cathode current density (A/dm)

Claims (3)

[Claims] (1) Zn^2^+ 5 to 20 g/l, Ni^2^+ 0.4 to 4.0 g/l, however, Zn^2^+/Ni^2^
+ (weight ratio) is 4 to 12.5, and further contains N-aminoethylethanolamine, ethylenediamine, diethylenetriamine, triethylenetetramine,
0.04 mol/l or more of one or more amine-based chelating agents selected from the group consisting of tetraethylenepentamine and pentaethylenehexamine, and 15 to 15% of triethanolamine.
An alkaline cyanide-free zinc-nickel alloy plating solution containing 60 g/l and an effective amount of a brightener. (2) The plating solution according to claim 1, wherein the brightener comprises a reaction product of an amine and epichlorohydrin and an aromatic aldehyde. (3) The plating solution according to claim 1, wherein the brightener comprises a quaternized pyridine compound.